Critical Raw Materials Substitution Profiles September 2013

Critical Raw Materials Substitution Profiles September 2013

Revised May 2015

Authors

Luis TERCERO ESPINOZA and Torsten HUMMEN (Fraunhofer Institute for Systems and Innovation Research ISI)Aymeric BRUNOT (CEA - Commissariat à l’Energie Atomique et aux Energies Alternatives)Arjan HOVESTAD (TNO Netherlands Organisation for Applied Scientific Research) Iratxe PEÑA GARAY and Daniela VELTE (Tecnalia)Lena SMUK and Jelena TODOROVIC (SP Sveriges Tekniska Forskningsinstitut AB)Casper VAN DER EIJK (SINTEF)Catherine JOCE (Chemistry Innovation)

Contact

Dr. Luis A. TERCERO ESPINOZA Coordinator of Business Unit Systemic Risks Competence Center Sustainability and Infrastructure Systems Fraunhofer Institute for Systems and Innovation Research ISI Breslauer Str. 48, D-76139 Karlsruhe [email protected], Tel. +49 721 6809-401

Reproduction is authorised provided the source is acknowledged.

This document is available on the internet at: http://cdn.awsripple.com/www.criticalrawmaterials.eu/uploads/D3.3-Raw-Materials-Profiles1.pdf

This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement No 319024.

The Critical Raw Materials Substitution Profiles In order to understand the opportunities and challenges presented by critical raw materials, and the areas where substitution could offer a solution, it was important to look at each individually. This report, the Critical Raw Materials Substitution Profiles, is a compilation of detailed profiles on each of the 14 materials identified as critical by the European Commission in 2010. Each raw material profile provides a detailed analysis of the end uses of the material and goes on to examine where there are already substitution options or where alternatives might be easily developed. Development of the Critical Raw Materials Substitution Report was led by the Fraunhofer Institute for Systems and Innovation Research, in collaboration with CRM_InnoNet project partners.

Further readingCRM_InnoNet has also completed detailed supply chain analysis of applications in the ICT and electronics, energy and transport sectors. These reports can be downloaded from the website: http://www.criticalrawmaterials.eu/documents/

To join the Network or to find out more, please get in touch;

www.criticalrawmaterials.eu Twitter @CRM_InnoNet [email protected]

What is substitution?

Substitution is one strategy that can reduce the reliance of a company, sector or economy on imported critical raw materials. Other strategies include increased recycling or primary extraction. CRM_InnoNet is exploring where the strategy of substitution has the best economic and technological potential for European industry.

There are four main substitution strategies:

What is CRM_InnoNet?

The Innovation Network for Substitution of Critical Raw Materials (CRM_InnoNet) is a collaborative project facilitating networking and delivering European roadmaps on the topic of substitution of critical raw

materials.

Document description

This document includes substitution profiles for each of the 14 raw materials identified as critical for the EU

in 2010. These are:

Antimony

Beryllium

Cobalt

Fluorspar

Gallium

Germanium

Graphite

Indium

Magnesium

Niobium

Platinum Group Metals

Rare Earth Elements

Tantalum

Tungsten

Each profile includes a description of supply, main uses and an assessment of current substitution

possibilities for each of the CRM in a way that is compatible with the work of the Ad-hoc Working Group on

defining Critical Raw Materials.

Compared to the original version (September 2013), this document includes (limited) changes to the

technical parts of the profiles for fluorspar, magnesium, rare earths, tungsten, and beryllium as well as to

the market part of the indium profile. These changes arise from feedback from the public delivered between

September 2013 and February 2015.

1. Antimony

Antimony is a semimetal, which can usually be found in its most stable metallic form. In its metallic form it is

physically bright, silvery, with a metallic lustre and average hardness and brittleness. Antimony is a poor

conductor of heat and electricity. Antimony and many of its compounds are toxic.1

Antimony is mined both as a main metal and as a by-product: The main antimony ore is antimony sulfide

(stibnite), but lead and copper ores often contain antimony, which is concentrated as a by-product and

obtained during the recovery of the main metal. Antimony is recovered in its metallic form from ore primarily

through pyrometallurgical techniques.2,3 The production of antimony is currently concentrated mainly in

China and the average price of antimony metal was about 3US$/kg in 2011* (see also Figure 2).4 After a

peak in 2011, the price has been generally decreasing over recent years.5

Figure 1: Distribution of antimony production6 and corresponding scores of the producing countries in the

Human Development Index (HDI),7 Environmental Performance Index (EPI),8 and World Governance

Indicators (WGI).9 Both the EPI and WGI are used to assess supply risks with the EU methodology for

determining critical raw materials.10 CHN = China.

* New York dealer price for 99.5% to 99.6% metal, c.i.f. U.S. ports.

Figure 2: Antimony price development during 1980 – 2011. The unit value of antimony reports the value of

1 metric ton (t) of antimony apparent consumption (estimated).11

Uses and Substitutability

Flame retardants

With a share of 71% of antimony consumption, antimony as antimony trioxide is mainly used for flame

retardants. The main applications within this sector include polyvinylchloride (PVC) for conveyor belts for

example in mines, cable coatings; coated fabrics for wall coverings and cushion covers, among others.

Moreover, it is used as high impact polystyrenes for television backs and domestic electrical appliances, as

well as housings for electrical equipment (including PCs). Polyethylene and propylene is primarily used for

wire sheathing and electrical conduits in buildings. Polyamides and engineering plastics such as nylons for

automotive uses, industrial equipment, and electric moulded parts as well as unsaturated polyesters for

applications such as building panels, automotive parts, and lifeboat hulls are further typical uses of

antimony.2

When antimony trioxide is combined with a halogen, flame retardant properties are imparted to several

materials through the formation of halides. Antimony halides promote reactions that cause the formation of

carbonaceous char rather than volatile gases. This char then acts as a heat shield that retards the

breakdown of the plastics, thus preventing the release of flammable gases.2

Antimony trioxide can be substituted with selected organic compounds, hydrated aluminum oxide or

mixtures of zinc oxide and boric oxide.4,12 However, while substitutes are available, in general, antimony is

seen to offer superior performance.

Lead alloys2

The second largest application for antimony is in lead alloys, making up a market share of 9%. Due to its

weak mechanical properties, it is mainly used in numerous alloys with lead and tin. The final use of the

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alloy is determined by both the percentage of antimony in the alloy as well as the other compounds

present.

For antimonial, or hard, lead alloys containing antimony between 1-15%, the presence of antimony results

in an increase of tensile strength, rendering the material more robust to stresses enforced by charging and

discharging reactions. Antimonial lead alloys that contain 1-9% of antimony are used for cable sheathing

and lead pipes, whereas the same alloys with 7-12% antimony are used for storage batteries and with an

antimony content of 12-15% they are used for small-arms ammunition.

Antimonial lead alloys with an antimony content between 1.5-3% are mainly applied for grid plates, straps,

and terminals of lead-acid batteries. Here, the addition of antimony improves fluidity, making the casting of

battery grids easier. Tensile strength is also increased, as is the electrochemical stability of lead.

Babitt metals include both ternary tin-antimony-copper alloys and quaternary tin-antimony-copper-lead

alloys, in both cases with a share of antimony ranging between 4.5-14%. Babitt metals are applied in low

load bearings. The addition of antimony to the alloy results in good anti-seizure properties and corrosion

resistance on the one side but low fatigue strength on the other side. Heavy load bearings, which require a

higher fatigue resistance for applications such as railways, use quaternary tin-antimony-copper-lead alloys

with an antimony share between 8 and 15%.

Type metals are antimony-lead alloys containing 2.5 – 25 % antimony. These alloys are used in the printing

industry and the antimony is added in order to lower the casting temperature, increase the hardness and

minimize shrinkage during freezing.

Brittania Metal and Pewter contain 7 - 20% antimony which increases the hardness of the metal and allows

a highly polished surface to be obtained. These metals are used for the manufacture of vases, lamps,

candlesticks, tea and coffee services, and other decorative applications.

Tin-lead alloys with an antimony share of less than 1% are used for soldering, whereby the antimony

increases the hardness of the alloy.

Antimionide contains, in addition to antimony, indium, aluminum and gallium. Antimony is added due to its

electrochemical properties as the applications include dopants in semiconductors for infrared detectors,

Hall-effect devices and diodes.

In general, combinations of cadmium, calcium, copper, selenium, strontium, sulfur and tin can substitute

antimony in most lead alloys.4

Rubber

For the vulcanization of red rubber compounds, a 7% share of antimony is utilized. Antimony pentasulfide,

Sb2S5, adds the required flexibility.2 It is difficult to substitute.13

Glass

The glass industry represents a 5% share of antimony use in the form of sodium hexahydroxyantimonate.

This compound is prepared by melting antimony or antimony oxides with excess sodium nitrate and is used

as an opacifier for glass and enamels.2 Glass containing antimony trioxide or sodium antimonate is used for

television tubes, as the oxide removes color and gas bubbles. Substitutes include compounds of chromium,

tin, titanium, zinc and zirconium.4 Therefore, it is comparatively easy to substitute.13

Catalysts

Catalysts make up 4% of antimony use, mostly for the polymerization catalyst in the manufacture of

polyester fibres, which requires antimony trioxide.2 A potential substitute is titanium catalysts, which can be

inactivated when a dulling agent is applied. There are some concerns around heavy metals in plastics

leaching e.g. into drinking water. However, titanium catalysts are not expected to replace antimony in PET

production to a significant extent with 2020 as a time horizon (even though alternatives exist at the R&D

stage) as there is no regulatory pressure from the FDA or the EC. Therefore antimony is assumed to be

currently difficult to replace.14

Pigments & Others2

Pigments and other applications for antimony result in a 4% antimony use. Chromate pigments apply

antimony trioxide for its unique pigmentation properties. However, compounds of chromium, tin, titanium,

zinc and zirconium could be used as substitutes.4 Another use for antimony is as an opacifier for ceramic

glazes and as a frit. Antimony trioxide is used in these applications as well. Antimony is comparatively easy

to substitute in its use for pigments.13

Summary

The demand for antimony is dominated by its use in flame retardants (as antimony trioxide). Because the

applications—and requirements—vary widely, there are options for substituting antimony trioxide partially

or, in some cases, completely. Also, substitutes are available for its use in lead alloys, glass & pigments,

apparently with limited loss of performance or additional costs. This is not the case for rubber and catalysts,

where the use of antimony brings substantial advantages in either performance or costs.

Figure 3: Distribution of end-uses and corresponding substitutability assessment for antimony. The manner

and scaling of the assessment is compatible with the work of the Ad-hoc Working Group on Defining

Critical Raw Materials (2010).

References 1 Haynes WM (ed.) (2012) CRC Handbook of Chemistry and Physics, 93rd edn.: Taylor & Francis 2 Grund, S. C., Hanusch, K., Breunig, H. J., Wolf, H. U. (2006) Antimony and Antimony Compounds, in:

Ullmann's Encyclopedia of Industrial Chemistry, pp. 11–42. Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA

3 Butterman W.C., Carlin JF, JR. (2004) Antimony. Open-File Report 03-019 4 Carlin, J. F., JR. (2013) Antimony, in: U.S. Geological Survey (ed.) Mineral commodity summaries

2013, pp. 19–20 5 Metal Bulletin Antimony MB free market in warehouse $ per tonne monthly average: Latest Metal

Prices Tracking and Comparison Tool. http://www.metalbulletin.com/My-price-book.html?price=34138. Accessed 3 September 2013

6 Reichl C, Schatz M, Zsak G (2013) World Mining Data: Production of Mineral Raw Materials of individual Countries, by Minerals. in 2011 in metric tonnes

7 United Nations Development Programme (UNDP) (2013) The 2013 Human Development Report – "The Rise of the South: Human Progress in a Diverse World"

8 Yale Center for Environmental Law and Policy (YCELP) (2013) Downloads | Environmental Performance Index. http://epi.yale.edu/downloads. Accessed 26 July 2013

9 World Bank Group (2013) Worldwide Governance Indicators. http://info.worldbank.org/governance/wgi/sc_country.asp. Accessed 26 July 2013

10 Ad-hoc Working Group on defining critical raw materials (2010) Critical raw materials for the EU: European Commission

11 Buckingham, D., Carlin, J., JR. (2012) Antimony: Supply-Demand Statistics, in: U.S. Geological Survey Minerals Information

12 Borax Firebrake ZB: An unique zinc borate combining the optimum effects of zinc and boron oxides and water release for developing fire retardant formulations processable up to 290 °C. http://www.borax.com/product/firebrake-zb.aspx. Accessed 28 August 2013

13 Eurometaux (2013) Antimony Substitutability. personal notification 14 Joce C (2013) Antimony Substitutability. personal notification

2. Beryllium

Beryllium has been commercially available since the 1920’s, when it was used to improve the mechanical

properties of copper alloys. This is the main use still today, leading to some of the strongest copper-based

alloys which, at the same time, retain a high electrical conductivity. Pure beryllium exhibits a low density

coupled to a high modulus of elasticity (resulting in a remarkably high specific strength), one of the highest

melting points of the light metals and a high conductivity for electricity and heat. It also reflects IR, transmits

X-rays well, absorbs neutrons, and resists attacks by concentrated nitric acid. Furthermore, it resists

oxidation in air at temperatures up to 600 °C. However, a high price, its toxic effects on the lungs if inhaled

(requiring strict preventive measures in manufacturing), and the room-temperature susceptibility to brittle

fracture of the metal are drawbacks of beryllium.1–3

Beryllium is mainly (≈ 95%) produced from ores containing 0.3% – 1.5% beryllium. In addition, it can be

obtained in small quantities as a by-product (beryl) of emerald extraction.4 The largest producer of beryllium

worldwide is the USA.5

Figure 1: Distribution of beryllium production5 and corresponding scores of the producing countries in the

Human Development Index (HDI)6, Environmental Performance Index (EPI)7, and World Governance


determining critical raw materials.9 USA = United States of America; CHN = China.

Beryllium is one of the most expensive raw materials. Its price increased over the last few years up to

approximately 93 US$/kg in 2011 and is recovering from a peak (104 US$/kg) in 2010.*5

* Unit value, annual average, beryllium-copper master alloy, dollars per kg contained beryllium: Calculated from gross

weight and customs value of imports; beryllium content estimated to be 4%.

Figure 2: Beryllium price development during 1980 – 2011. The unit value is defined as the value of 1

metric ton (t) of beryllium apparent consumption (estimated).10

Uses and substitutability

Mechanical Equipment

With a share of 25%, the manufacture of mechanical equipment represents a key use of beryllium.

Beryllium is mainly used alloyed in small amounts with copper and nickel to improve their ability to conduct

electricity and heat, coupled with high strength and machinability and formability.11 The combination of

strength and ductility is controlled by both cold work and age hardening of the alloys. The main applications

of these alloys are conductive spring terminals of high reliability electrical and electronic connectors (see

below), drilling and mineral mining equipment, undersea housings of fiber optic cables, metal and plastic

casting moulds, springs as well as electrode holders and components of welding robots.12,13

Since beryllium is only utilized in applications in which its properties are crucial, it is hard to substitute in

general.3 Nevertheless, if it is used exclusively due to its mechanical properties, beryllium can be

substituted with titanium, magnesium, aluminium and their alloys or with carbon fiber composites. If only a

thermal improvement is required, beryllium can be substituted with aluminium metal matrix composites with

added silicon carbide / boron nitride.13 However, there are no currently available materials that exhitbit

these properties in combination.14

Electronics & ICT

The electronics & ICT sector accounts for 20% of European beryllium end-use, virtually all of which is used

in the form of copper-beryllium alloys for durable and reliable conductive spring terminals of electrical and

electronic connectors in computers, mobile phone handsets and infrastructure equipment, power amplifiers

and civil aviation radar systems. Additionally, copper beryllium alloys are used for electrical spring contacts

in switches and relays of electronic and telecommunications equipment.3,11,13,15

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If used solely for its mechanical properties, copper alloys containing beryllium can be substituted by other

alloys such as phosphor bronze or copper silicon, but at the—for electronics and ICT unacceptable—cost

of electrical conductivity.14 Reducing or eliminating beryllium from the copper alloys leads to decreased

reliability and longevity of the components.

The ceramic form, BeO, beryllium oxide or beryllia, has an unusual combination of properties, the most

important of which are its high electrical insulation, coupled with a hardness only slightly lower than that of

diamond, and thermal conductivity an order of magnitude greater than that of alumina. Its low dielectric

constant and low loss index promote its use as an electronics circuit substrate with extremely good

performance at high frequencies. Only a small quantity of beryllium is used in beryllium oxide ceramic

components used in applications such as high power RF amplifiers, IC and other electronic chip substrates

for high power radar systems.3,14 For some of the less demanding electronic packaging thermal

management applications, beryllium oxide ceramic has been substituted for with silicon carbide / boron

nitride aluminium metal matrix composites but with reduced efficiency and loss of electrical insulation.5,16

No adequate substitute has been found for more demanding applications such as medical excimer laser

bore tubes and high power RF travelling wave tube amplifiers and RF amplifiers.14,16

Electrical equipment & domestic appliances

The electrical equipment & domestic appliances sector has a share of 20% and uses copper beryllium and

nickel beryllium because of the properties outlined above. Typical applications include: Switches,

thermostat controls and relays, electrical and electronic connectors used in appliances, fire sprinkler water

control springs, pressure gauges and many other conductive spring applications. In household applianace

temperature and other function controls as well as in relays, beryllium may be substituted (with loss of

performance) by the use of nickel and silicon, tin, titanium, or other alloying elements or phosphor bronze

alloys. It is reported that in numerous cases, earlier replacements of beryllium with lesser performing alloys

has lead to (unacceptably) shorter product lifetimes such that copper beryllium alloys have been

reintroduced to restore performance.2,16

Road transport

The road transport sector, which has a share of 15% in European beryllium end-use, mainly uses beryllium

copper alloys in electrical and electronic connectors for high reliability automobile applications such as air-

bag crash sensors, anti-lock brake systems, traction control and all engine sensors, navigation and

entertainment systems and in the form of aluminium beryllium master alloys containing 1-5% beryllium, as

a metallurgical structure modifier and magnesium addition conditioner for aluminium and magnesium alloys

and castings.3,16 Purpose and substitutability of beryllium is as outlined above. However, the loss of

performance upon substitution is generally unacceptable in safety-related applications.

Aerospace13

A 13% share of total beryllium consumption goes to use in alloys for aircrafts, mainly because of its

mechanical properties, particularly the specific strength and stiffness of the metallic beryllium form for

structural applications (especially at extremely low temperatures), and the unique combination of strength,

conductivity, low friction and machinability of the copper beryllium alloy form. Copper-beryllium is used for

low friction applications such as in aircraft landing gear bearings, for rod-end bushings and no-fail

emergency door fasteners, and for its thermal conductivity in pitot tube castings. Possible substitutes are

copper alloys containing nickel and silicon, tin, titanium, or other alloying elements or phosphor bronze

alloys (copper-tin-phosphorus), steel or titanium. However, there are no substitute alloys that provide the

same combination of properties or long term reliability, which is generally unacceptable in safety-related

aerospace components.5,13,14,16 Another major application for copper beryllium alloys in aerospace is as the

female connector terminals in electronic and electrical connectors (thousands of connectors per aircraft),

which are subject to intense vibration and stresses, yet must perform reliably over the 30 – 40 year lifespan

of an aircraft. Theoretically, copper alloys containing nickel and silicon, tin, or titanium, or phosphor bronze

alloys are alternatives. In practice, however, there is a loss of performance that is inadmissible in safety-

related applications.16

Beryllium metal is used for example in gyroscope gimbals and yokes for use in guidance, navigational and

targeting systems for helicopters and aircraft, as well as in satellite mounted directional control systems.

For individual mechanical properties, the metallic beryllium used in aerospace applications could be

substituted for by certain metal matrix or organic composites, high-strength alloys of aluminium,

magnesium, steel, or titanium. However, no other material offers the specific stiffness and strength

combination that beryllium does, making it irreplaceable in practice.2,16,17

Others

Other final consumer goods make up 7% beryllium consumption due to the fact that it is relatively

transparent to X-rays. Copper beryllium is used in medical isotope production nuclear reactors; fire

sprinkler water control valve springs and X-ray lithography for the reproduction of micro-miniature

integrated circuits. Furthermore it is used in X-Ray transparent windows, and mirrors for terrestrial and

space mounted astronomical telescopes. Beryllium oxide is necessary in ceramic applications, medical

excimer laser beam focusing and its control components.13

Summary

Beryllium, being a very expensive metal, tends to be used only where its properties are needed and no

reasonable substitute can deliver the desired result. In particular in safety related applications (e.g. anti-lock

brake systems in cars, some aerospace), reduced performance/durability is unacceptable.

Figure 3: Distribution of end-uses18

and corresponding substitutability assessment for beryllium. The

manner and scaling of the assessment is compatible with the work of the Ad-hoc Working Group on

Defining Critical Raw Materials (2010).

References

1 BesT - Beryllium Science & Technology Association (2015) Safety Model. http://beryllium.eu/working-

safely-with-beryllium/protecting-workers/safety-model/. Accessed 29 May 2015

2 BesT - Beryllium Science & Technology Association (2013) Critical Applications of Beryllium.

http://beryllium.eu/about-beryllium-and-beryllium-alloys/critical-applications-of-beryllium/. Accessed 29

May 2015

3 Svilar, M., Schuster, G., Civic, T., Sabey, P., Vidal, E., Freeman, S., Petzow, G., Aldinger, F., Jönsson,

S., Welge, P., Kampen, V., Mensing, T., Brüning, T. (2013) Beryllium and Beryllium Compounds, in:

Ullmann's Encyclopedia of Industrial Chemistry, pp. 1–35. Weinheim, Germany: Wiley-VCH Verlag

GmbH & Co. KGaA

4 BesT - Beryllium Science & Technology Association (2013) Beryllium Extraction.

http://beryllium.eu/about-beryllium-and-beryllium-alloys/facts-and-figures/beryllium-extraction/.

Accessed 15 May 2013

5 Jaskula, B. W. (2013) Beryllium, in: U.S. Geological Survey (ed.) Mineral Commodity Summaries

2013, pp. 28–29

6 United Nations Development Programme (UNDP) (2013) The 2013 Human Development Report –

"The Rise of the South: Human Progress in a Diverse World"

7 Yale Center for Environmental Law and Policy (YCELP) (2013) Downloads | Environmental

Performance Index. http://epi.yale.edu/downloads. Accessed 26 July 2013

8 World Bank Group (2013) Worldwide Governance Indicators.

http://info.worldbank.org/governance/wgi/sc_country.asp. Accessed 26 July 2013

9 Ad-hoc Working Group on defining critical raw materials (2010) Critical raw materials for the EU:

European Commission

10 Buckingham, D., Cunningham, L., Shedd, K., Jaskula, B. (2012) Beryllium: Supply-Demand Statistics,

in: U.S. Geological Survey (ed.) Minerals Information

11 Royal Society of Chemistry (2013) Beryllium. http://www.rsc.org/periodic-table/element/4/beryllium.

Accessed 15 May 2013

12 Chemicool.com (2013) Beryllium. http://www.chemicool.com/elements/beryllium.html. Accessed 15

May 2013

13 BesT - Beryllium Science & Technology Association (2013) Substitutes for beryllium and alloys

containing beryllium. Email

14 BesT - Beryllium Science & Technology Association (2015) Alternate Materials.

http://beryllium.eu/about-beryllium-and-beryllium-alloys/alternate-materials/. Accessed 29 May 2015

15 BesT - Beryllium Science & Technology Association (2013) Uses & Applications of Beryllium.

http://beryllium.eu/about-beryllium-and-beryllium-alloys/uses-and-applications-of-beryllium/. Accessed

15 May 2013

16 BesT - Beryllium Science & Technology Association (2015) Substitution of beryllium. E-Mail

17 BesT - Beryllium Science & Technology Association (2015) Uses of Beryllium.

http://beryllium.eu/about-beryllium-and-beryllium-alloys/uses-and-applications-of-beryllium/. Accessed

29 May 2015

18 Materion (2013) Investor Presentation.

http://files.shareholder.com/downloads/BW/2469474044x0x659351/73c733fd%E2%80%90043d%E2%

80%904959%E2%80%90972de68ddb89fcd4/Investor_Presentation_May_2013.pdf. Accessed 15 May

2015

3. Cobalt

Cobalt is shiny, grey, brittle metal with a close packed hexagonal (CPH) crystal structure at room

temperature but which changes at 421 °C to a face centred cubic form. It has a high melting point (1493 °C)

and boiling point (3100 ºC) and it maintains its strength and integrity at extremely high temperatures. In

addition, cobalt, as well as nickel and iron, is ferromagnetic and retains this property up to 1100 °C, a

higher temperature (Curie point) than any other material. Hence, one of its key uses is in magnets for high-

temperature applications.

Cobalt is rarely used as a structural material in its pure form but rather is employed as an alloying element.

The first use of cobalt was as a pigment in conjunction with silica to produce intense blue colours. This

remained as the main use of cobalt until the 20th century. However, cobalt is a very versatile metal and over

the 20th century it started to be employed for a wide array of applications such as metallurgical uses (e.g.

superalloys), magnets, batteries, pigments, catalysts, etc.

In addition to its industrial uses and relevance, cobalt is one of the around 20 elements which are essential

to humans. Cobalt is contained in vitamin B12, which is important in protein formation and DNA regulation.

Cobalt is recovered both as a main metal from dedicated cobalt mines (minor source) and as a by-product

(major source), especially of nickel and copper mining.1,2 It is only extracted alone from Moroccan and

Canadian arsenide ores. The main producer of cobalt worldwide is the Democratic Republic of Congo.

Historical price data are shown in Figure 2. The average price in 2011 was 8.18 US$/kg*.3 When looking at

the price of cobalt in more detail, the large scale fluctuation seen in Figure 2 continues. The price

decreased in the beginning of 2013, rose up in the middle of the year and felt down after this peak

recently.4

Figure 1: Distribution of cobalt production5 and corresponding scores of the producing countries in the


* Spot, cathode: As reported by Platts Metals Week

Indicators (WGI)8. Both the EPI and WGI are used to assess supply risks with the EU methodology for

determining critical raw materials 9. COD = D. R. Congo; CAN = Canada; CHN = China.

Figure 2: Cobalt price development during 1980 – 2011. The unit value is defined as the value of 1 t of

cobalt apparent consumption (estimated).10.


Batteries

The increase in demand for portable electronic devices since the 1980s boosted the demand for high

capacity rechargeable batteries. In this context, rechargeable batteries containing cobalt display a high

energy density, along with the capability of quick charging and low stand-by energy losses. For this reason,

one of the preferred uses of cobalt is in batteries of portable devices, such as cell phones, laptops,

smartphones, tablets, etc. Lithium-ion (Li-ion) batteries containing cobalt-based cathodes contain the most

cobalt with a market share of 30%, but nickel metal hydride (Ni-MH) and nickel cadmium (NiCd) batteries

also use cobalt. Overall, close to 30% of cobalt demand is attributed to its use in batteries.

A continued increase in demand for Li-ion is expected in the electronics sectors correlating to the surge in

demand for portable devices (especially telephones) in emerging economies. Moreover, emerging use of

cobalt in some rechargeable batteries for electric vehicle applications is expected to increase cobalt

demand over the next ten years.

Substitution of cobalt in Li-Ion batteries is potentially possible. Although LiCoO2 is the preferred material for

portable battery applications11, both LiNiO2 and LiMn2O4 can also be used for the same purpose. In

addition, latest industry predictions indicate that many of the disadvantages of alternative materials have

been overcome and although rechargeable battery demand is expected to increase rapidly in the next few

years, cobalt demand in this application could remain stable or even decrease slightly.

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In addition, the recycling and recovery rates of cobalt from end-of-life batteries are promising. Recent

research 12,13 shows that new recycling strategies are being implemented to increase the recovery valuable

materials, especially cobalt, from batteries. In this regard, it should be noted that high recycling rates of

end-of-life cobalt are reported14. Finally, it is worth mentioning the industrial scale end of life rechargeable

batteries recycling facility set up by Umicore in Belgium in 201115.

Superalloys and magnets

Cobalt-based super-alloys are one of the largest markets for cobalt 16. They have their origins in the Stellite

alloys patented in the early 1990’s by Elwood Haynes. Cobalt-based super-alloys have higher melting

points than nickel-based ones and retain their strength at higher temperatures. They also show superior

weldability, hot corrosion and thermal fatigue resistance than nickel-based alloys.17 These properties make

them suitable for use in turbine blades for gas turbines and jet aircraft engines.18

Fiber-reinforced metal matrix composites (MMC), ceramic-ceramic and carbon-carbon composites, titanium

aluminides, nickel-based single crystal alloys or iron-based super-alloys may substitute cobalt-based ones

in these applications to some extent. Loss of performance at high temperatures (due to the unique physical

properties of Co) can, however, be expected in some cases.19 Therefore, substitution for cobalt in jet

engine castings will probably not occur and cannot be considered as a meaningful solution to the cobalt

supply problem.

Cobalt is also used in samarium-cobalt and aluminium-nickel-cobalt permanent magnets. These are widely

used in electric motors, electric guitar pickups, microphones, sensors, loudspeakers, traveling-wave tubes,

and cow magnets.20 They have comparable strength but much higher temperature ratings and higher

coercivity than neodymium magnets.21

There is some potential for substitution of cobalt-alloyed magnets by nickel-iron or neodymium-iron-boron

ones. The substitution seems to be difficult though in high temperature applications since cobalt-alloyed

magnets have significantly higher Curie temperatures and are the only magnets that have useful

magnetism even when heated red-hot.22

Hard metal and surface treatment

Around 12% of the final cobalt consumed is destined to hard metal and surface treatment. Cobalt is used in

cemented carbides as a binder phase. The carbides are usually Tungsten-Carbides although sometimes

also Titanium-Carbo-Nitrides or Tantalum-Carbides are used. The binder phase is typically between 5 and

30 vol% of the component. The more hard carbide particles are within the material, the harder it is but the

less tough it behaves during loading; and, vice versa, significant increases in toughness are achieved by a

higher amount of metallic binder at the expense of hardness.

The high solubility of tungsten carbide (WC) in the solid and liquid cobalt binder at high temperatures

provides a very good wetting of WC and results in an excellent densification during liquid phase sintering

and in a pore-free structure.23 There is potential for substitution of cobalt-iron-copper or iron-copper in

diamond tools. Research and development in this field is very active and most of the competing matrix

materials have a lower cost.24–26 However, there is a certain loss of performance.

Pigments

Pigments account for 9% of cobalt use. The unique colouring properties of cobalt produce light blue to

black pigmentation for ceramics, glass, porcelain, enamel, paint and inks 2, whereby the amount of cobalt

oxide added to the final product depends on the required colour. As cobalt(II) acetate it is used in the

production of drying agents for inks and pigments. Cerium, iron, lead, manganese, and vanadium can all be

used as substitutes for cobalt for this application, unfortunately not necessarily with the same results.3

Catalysts

Cobalt is widely used in the oil and gas sector. It is used in hydrodesulfurization (a catalytic chemical

process widely used to remove sulfur from natural gas and from refined petroleum products such as

gasoline or petrol), where the catalyst must be sulfur resistant. 27 Catalysts account for 6% of cobalt use.

Cobalt catalysts also play an important role bulk chemical production of PTA (a monomeric precursor to

polyester) and a process called hydroformylation which generates aldehydes and alcohols used in the

plastics and detergent markets.27

In addition, it is also used in the catalysis of gas to liquid processes. 28 The application of this technology is

expected to result in a major new demand for cobalt. 29

Finally, a potential emerging use (and subsequent increase in demand) of cobalt is as catalyst in hydrogen

fuel cells.30

With regard to its application for hydrodesulfurization, ruthenium, molybdenum, nickel and tungsten can be

used depending on nature of the feed, instead of cobalt.3,31–33 Also alternative ultrasonic process can

dispense with the use of cobalt, and rhodium can serve as a substitute for hydroformylation catalysts.3

Others

There is still a remaining 8% of cobalt that is used for various other applications. Cobalt powders are used

for their high melting point, high-temperature strength and for the fact that they can be produced as a very

fine powder in binders for the diamond tool industry. For this application, cobalt can be substituted by

cobalt-iron-copper or iron-copper.1

Cobalt salts are used in agriculture as a supplement to animal feeds, as cobalt is an essential element in

the human and animal metabolism.2

The cobalt isotope Co60 is a strong gamma-ray emitter, which is used in the medical field for radiation

therapy. Other medical applications for cobalt include the use of cobalt-chromium alloys for cast denture

bases, complex partial dentures, and some types of bridgework for dental applications due to cobalt’s high

strength and tension properties. The good castability, resistance to tarnish, compatibility with mouth

tissues, high strength and stiffness, and low density makes cobalt suitable for these applications. Similar

cobalt-chromium alloys are also used for surgical implants and bone replacement (e.g. hip joint

replacement) and repair because of cobalt’s resistance to corrosion and high fatigue strength of the cobalt-

chromium-alloy.1

Other applications include the manufacture of Elgiloy, a spring alloy containing 40% cobalt, 20% chromium,

15% nickel, 7% molybdenum, and 2% manganese, alloys composed of cobalt-nickel or cobalt-iron-

magnesium-carbon used as magnetic recording materials and cobalt silicate, which is applied for electrical

connectors and integrated circuits. A material with a very low coefficient of thermal expansion results from

alloying cobalt in low-expansion iron–nickel alloys of the Invar type.1

Summary

Substitution of cobalt in Li-Ion batteries—the single largest application—is possible, although this is not the

preferred option. Moreover, in this field, recycling and recovery hold some promising potential. Similarly,

substitution comes at the expense of performance due to the unique properties of cobalt in superalloys,

magnets, hard metals and surface treatment. Cobalt substitution in pigments by acetate, cerium, iron, etc.

is possible but also leads to a decrease in performance. Finally, cobalt as a catalyst may be substituted to

some extent for hydrodesulfurization and hydroformylation proceses.

Figure 3: Distribution of end-uses and corresponding substitutability assessment for cobalt. The manner



References 1 Donaldson, J. D., Beyersmann, D. (2010) Cobalt and Cobalt Compounds, in: Ullmann's Encyclopedia

of Industrial Chemistry, pp. 429–465. Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA 2 Hannis, S., Bide, T. (2009) Cobalt, in: British Geological Survey (ed.) Commodity Profiles 3 Shedd, K. B. (2013) Cobalt, in: U.S. Geological Survey (ed.) Mineral commodity summaries 2013, pp.

46–47 4 Metal-Pages Cobalt metal prices, news and information. http://www.metal-

pages.com/metals/cobalt/metal-prices-news-information/. Accessed 3 September 2013 5 Reichl C, Schatz M, Zsak G (2013) World Mining Data: Production of Mineral Raw Materials of

individual Countries, by Minerals. in 2011 in metric tonnes 6 United Nations Development Programme (UNDP) (2013) The 2013 Human Development Report –

"The Rise of the South: Human Progress in a Diverse World" 7 Yale Center for Environmental Law and Policy (YCELP) (2013) Downloads | Environmental

Performance Index. http://epi.yale.edu/downloads. Accessed 26 July 2013 8 World Bank Group (2013) Worldwide Governance Indicators.

http://info.worldbank.org/governance/wgi/sc_country.asp. Accessed 26 July 2013 9 Ad-hoc Working Group on defining critical raw materials (2010) Critical raw materials for the EU:

European Commission 10 Buckingham, D., Shedd, K. (2012) Cobalt: Supply-Demand Statistics, in: U.S. Geological Survey

Minerals Information 11 Cobalt Development Institute (2013) Cobalt Development Institute. http://www.thecdi.com/. Accessed 8

August 2013 12 Jha, A. K., Jha, M. K., Kumari, A., Sahu, S. K., Kumar, V., Pandey, B. D. (2013) Selective separation

and recovery of cobalt from leach liquor of discarded Li-ion batteries using thiophosphinic extractant. Separation and Purification Technology 104, 160–166. 10.1016/j.seppur.2012.11.024

13 Iizuka, A., Yamashita, Y., Nagasawa, H., Yamasaki, A., Yanagisawa, Y. (2013) Separation of lithium and cobalt from waste lithium-ion batteries via bipolar membrane electrodialysis coupled with chelation. Separation and Purification Technology 113, 33–41. 10.1016/j.seppur.2013.04.014

14 United Nations Environment Programme (UNEP) (2012) Metal stocks and recycling rates. http://www.unep.org/resourcepanel/Portals/24102/PDFs/Metals_Recycling_Rates_Summary.pdf

15 Umicore (2013) Battery Recycling. http://www.batteryrecycling.umicore.com/UBR/. Accessed 7 August 2013

16 Cobalt Development Institute (2011) Cobalt News. http://www.thecdi.com/cdi/images/news_pdf/cobalt_news_jan2011.pdf. Accessed 8 August 2013

17 Materialrulz (2010) Superalloys. http://materialrulz.weebly.com/uploads/7/9/5/1/795167/superalloys.pdf. Accessed 8 August 2013

18 Office of Technology Assessment (1985) Strategic Materials: Technologies to Reduce U.S. Import Vulnerability. Washington,DC: U.S. Congress

19 Cobalt Development Institute (2006) Cobalt Facts: Metallurgical uses. http://www.thecdi.com/cdi/images/documents/facts/COBALT_FACTS-Metallurgical_%20uses.pdf. Accessed 8 August 2013

20 Chemicool.com (2013) Cobalt. http://www.chemicool.com/elements/cobalt.html. Accessed 8 August 2013

21 Cobalt Development Institute (2013) Magnetic Alloys. http://www.thecdi.com/general.php?r=U6ENJWAVAL. Accessed 9 August 2013

22 Cobalt Development Institute (2006) Cobalt facts: Magnetic Alloys. http://www.thecdi.com/cdi/images/documents/facts/COBALT_FACTS-Magnetic_Alloys.pdf. Accessed 9 August 2013

23 Davis JR (1993) Properties and selection: Nonferrous alloys and special-purpose materials, 10th edn. Metals Park, Ohio: American Society for Metals

24 Subramanian, R., Schneibel, J. H. (1998) FeAl–TiC and FeAl–WC composites—melt infiltration processing, microstructure and mechanical properties. Materials Science and Engineering: A 244(1), 103–112. 10.1016/S0921-5093(97)00833-2

25 Mosbah, A. Y., Wexler, D., Calka, A. (2005) Abrasive wear of WC–FeAl composites. Wear 258(9), 1337–1341. 10.1016/j.wear.2004.09.061

26 Yusoff, M., Othman, R., Hussain, Z. (2011) Mechanical alloying and sintering of nanostructured tungsten carbide-reinforced copper composite and its characterization. Materials & Design 32(6), 3293–3298. 10.1016/j.matdes.2011.02.025

27 Cobalt Development Institute (2013) Catalysts. http://www.thecdi.com/general.php?r=12ENJWIVAD. Accessed 19 July 2013

28 Umicore (2013) Catalysts Production & Recycling. http://csm.umicore.com/applications/catalysts/. Accessed 19 July 2013

29 Idaho Cobalt (2013) Cobalt Uses. http://www.idahocobalt.com/s/CobaltUses.asp. Accessed 19 July 2013

30 Guo, S., Zhang, S., Wu, L., Sun, S. (2012) Co/CoO Nanoparticles Assembled on Graphene for Electrochemical Reduction of Oxygen. Angewandte Chemie International Edition 47(51), 11770–11773

31 Hielscher Ultrasonics - Ultrasound Technology (2012) Ultrasonic Alternative to Hydrodesulfurization. http://www.hielscher.com/ultrasonics/oil_desulfurization_01.htm. Accessed 19 July 2013

32 The Encyclopedia of Earth (2013) Hydrodesulfurization. http://www.eoearth.org/view/article/171121/#gen2. Accessed 19 July 2013

33 Chen X, Liang C (2012) Nickel silicides: an alternative and high sulfur resistant catalyst for hydrodesulfurization. http://events.dechema.de/Tagungen/Materials+for+Energy+_+EnMat+II/Congress+Planer/Datei_Handler-tagung-564-file-1082-p-127866.html. Accessed 19 July 2013

4. Fluorspar

The mineral fluorspar consists of 51.1% calcium and 48.9% fluorine in its pure form (CaF2). In this case, it

is colorless and transparent but different colors can be induced by impurities in the crystal structure. Most

fluorspar is extracted either in pure veins or in association with lead, silver, or zinc ores. Commercial

fluorspar is graded according to its quality and its specification into acid-grade, metallurgical grade and

ceramic grade.1 The largest current producer of fluorspar is China, followed by Mexico.

Figure 1: Distribution of fluorspar production2 and corresponding scores of the producing countries in the

Human Development Index (HDI)3, Environmental Performance Index (EPI)4 and World Governance


determining critical raw materials6. CHN = China; MEX = Mexico.

After dropping to a price of 0.101 US$/kg in 2006, the average price of metallurgical grade fluorspar rose to

approximately 0.11 US$/kg* in 2009. It is estimated that the price felt back to an amount of 0.101 US$/kg in

2010.7 The price of acid grade fluorspar is approximately double that value.

* Price: c.i.f. U.S. port

Figure 2: Fluorspar price development during 1975 – 2006. The unit value is defined as the value of 1 t of

fluorspar apparent consumption (estimated).8


Hydrofluoric acid

Fluorspar is widely used in the manufacturing of hydrofluoric acid or HF (52% of its end use) which serves

as feedstock for many different chemical processes. Hydrofluoric acid from fluorite (acid grade) is used in

the synthesis of fluorocarbons (CFCs, HCFCs, HFCs) or fluorine-bearing chemicals such as

pharmaceuticals, agrochemicals, non-stick coatings as well as in uranium processing. Another application

of hydrofluoric acid is as a catalyst for the petroleum industry.9 Fluorosilicic acid from the production of

phosphoric acid from apatite and fluorapatite has the potential to serve as a substitute for fluorspar as a

source of fluorine in HF production.10 Other possible substitutes are sodium fluoride, and sodium

fluorosilicate.1 Nevertheless, these substitutes are just principle alternatives, since none of them are put

into practice yet.

Steel

The steel sector consumes about 25% of total fluorspar. Metallurgical grade fluorspar is added as flux in

the manufacture of steel in open hearth oxygen and electric arc furnaces. Fluorspar lowers the melting

point and reduces slag viscosity. It can be substituted with aluminium smelting dross11, borax, calcium

chloride, iron oxides, manganese ore, silica sand and titanium oxide.10

Aluminium

With a market share of 18%, the aluminum sector is the third largest consumer of fluorspar. The reason for

this is that aluminum cannot be produced by an aqueous electrolytic process because hydrogen is

electrochemically much nobler than aluminum. Thus, liquid aluminum is produced by the electrolytic

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reduction of alumina (Al2O3) dissolved in an electrolyte (bath) containing approximately 65% cryolite

(NaF3∙3NaF). Synthetic cryolite is made from fluorspar (CaF2) by treating it with sulfuric acid to produce

hydrofluoric acid which is then reacted with sodium oxide (Na2O) and alumina to produce cryolite. Besides

serving as a solvent, cryolite lowers the melting point of the aluminium electrolysis bath to below 1000°C.1,9

Recent advances in the aluminium industry have decreased the consumption of fluorspar. In order to

minimize emissions of hydrogen fluoride (HF), fume treatment plants are used to capture the HF from the

cells and recycle it as aluminium fluoride for use in the smelting process.12

In addition, aluminium fluoride (AlF3), also produced using HF, is used in the production of aluminium. In

principle, fluorosilic acid, obtained from phosphate rock, can be used to produce HF (and thus synthetic

cryolite and AlF3), but this process has not been implemented on a large scale yet.9 Therefore, fluorspar

cannot be substituted in electrolysis-based aluminium production. A corbothermic reduction process, which

does not require fluorspar, is currently being developed by Alcoa (pilot stage).†

Others

In the residual market share (5%) ceramic grade fluorspar is used in milky or coloured glass or glass fibers,

which may contain 10 – 20% fluorite. Further applications are enamels for metallic or ceramic substrates

containing between 3 – 10% fluorite. Regarding these applications fluorspar is inserted as opacifier. Finally,

the addition of ceramic grade fluorspar to raw materials for cement enhances the clinkering temperature to

50 – 150 ºC.9

† SINTEF

Summary

Fluorspar is used as the main source of fluorine. As such, either the fluorine may be substitutable in a

process (e.g. in the steel industry) or alternative sources of fluorine may be used (such as fluorosilicic acid).

It is unclear at this time to what extent (by-product) fluorisilicic acid may supplant fluorspar as the principle

source of fluorine. In any case, this process would be a slow one.

Figure 3: Distribution of end-uses and corresponding substitutability assessment for fluorspar. The manner



References

1 British Geological Survey (2011) Fluorspar

2 Reichl C, Schatz M, Zsak G (2013) World Mining Data: Minerals Production








European Commission

7 Miller, M. M. (2011) Fluorspar, in: U.S. Geological Survey (ed.) Mineral Commodity Summaries 2011,

pp. 56–57

8 Kelly, T., Miller, M. (2012) Fluorspar: Supply-Demand Statistics, in: U.S. Geological Survey (ed.)

Minerals Information

9 Aigueperse, J., Mollard, P., Devillers, D., Chemla, M., Faron, R., Romano, R., Cuer, J. P. (2000)

Fluorine Compounds, Inorganic, in: Ullmann's Encyclopedia of Industrial Chemistry, pp. 397–441.

Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA

10 Miller, M. M. (2013) Fluorspar, in: U.S. Geological Survey (ed.) Mineral commodity summaries 2013,

pp. 56–57

11 SP Sveriges Tekniska Forskningsinstitut AB (2013) Fluorspar Substitutability. personal notification

12 Alstom (2013) Air quality control solutions for the aluminium industry.

http://www.alstom.com/Global/Power/Resources/Documents/Brochures/air-quality-control-for-the-

aluminium-industry-general-brochure.pdf

5. Gallium

Like aluminium, gallium is a soft, silvery metal.1 A particular concern for gallium criticality is its main use in

growing and emerging markets. Gallium is almost exclusively used as III-V semiconductor material in

electronics applications2 that grew fast in recent years and are forecast to continue growing rapidly in the

coming decades3,4.

Traces of gallium can be found in the minerals diaspore, sphalerite, germanite, bauxite and coal.1 As it is

primarily obtained from the circulation liquor in the Bayer process for aluminium oxide manufacture, gallium

is a by-product of aluminium production and is not extracted in its own right.5 After a period in which the

price of gallium increased up to a peak of 688 US$/kg*† in 2011, the price has declined. In 2013 the price of

gallium decreased continuously. Metal Bulletin #937} The leading producer is China, which has increased

its production capacity by a factor of five6. Its competitors are Kazakhstan and Ukraine.

Figure 1: Distribution of gallium production7 and corresponding scores of the producing countries in the

Human Development Index (HDI),8 Environmental Performance Index (EPI)9 and World Governance


determining critical raw materials.11 CHN = China; KAZ = Kazakhstan; URK = Ukraine.

* † Price, yearend, dollars per kilogram: Estimated based on the average values of U.S. imports for 99.9999% -and

99.99999% -pure gallium

Figure 2: Gallium price development during 1980 – 2011. The unit value is defined as the value of 1 ton (t)

of gallium apparent consumption (estimated).12


Gallium is almost exclusively used in III-V semiconductor compounds, in particular GaAs and GaN, for two

main applications fields:

Integrated circuits

Optoelectronic devices (LEDs, laser diodes and photo detectors, solar cells)

Integrated circuits

Semiconductor compounds used in integrated circuits (ICs) are currently the major application of gallium

constituting about 70% of overall gallium use.2 Integrated circuits with gallium compound semiconductors

specifically GaAs and GaN, are used in high-power and high-frequency electronics, due to higher electron

mobility, breakdown voltages and saturation velocity than silicon-based ICs. This faster and cleaner

electron transfer enables stable high power (wireless) communication devices, such as smart phones,

amplifiers, digital switches and microwave applications.4,13 These applications are all rapidly growing.3 Due

to their high radiation and temperature resistance the gallium-based ICs are ideal for space applications,

such as satellite dishes, and military use. The Ga compounds are either melt-grown wafers or thin films

prepared by metal organic chemical vapour deposition (MOCVD) from trimethyl gallium precursors.

Options for substitution of gallium in integrated systems are limited because, as a minor and relative costly

metal, Ga-based IC were specially develop for applications where established Si-based semiconductor and

integrated circuit technology do not fulfil the applications’ requirements. SiGe is a commercially available

alternative to GaAs exhibiting similar properties required for high-power and high-frequency electronics.14

SiGe is able to replace GaAs wafers in some integrated circuits (high performance radio frequency

applications), but it uses another critical raw material, germanium. Note that SiGe was developed as cost-

effective alternative to GaAs and not because of the gallium criticality as such. Integrated circuits are core

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components applied in a broad range of electronic product making component substitution instead of

material substitution also not possible without function or performance loss.

In conclusion, currently substitution of gallium in integrated circuits is possible for a limited number of

applications but only by materials containing another critical raw material.

Optoelectronic devices

Optoelectronics devices, such as laser diodes, photodiodes, LEDs and solar cells, constitute the other main

use of gallium. LEDs are used in lighting and displays and the demand for LEDs in solid state lighting

applications is growing fast due to governmental bans on the use of incandescent light bulbs. Photodiodes

are used in e.g. remote controls and laser diodes are used in telecommunication optical media (CD, DVD)

players. Gallium-based solar cells are exclusively used for space and military applications and

concentrated solar power. Thin film copper-indium-gallium-selenide (CIGS) solar cells are an emerging

technology for low-cost and high efficiency solar power generation.

As for the integrated circuits, gallium is combined with arsenic (GaAs), sulphur (GaN) or phosphor (GaP),

often including indium (InGaAs) or aluminium (AlGaAs), to produce III-V semiconductor compounds. Due to

their high electron velocity, compared to silicon, and their direct bandgap, Ga based semiconductors are

well suited to either convert electricity to light (LEDs, laser diodes) or vice versa (solar cells, photodiodes).

In multilayer stacks of these compounds a diode, created by a so-called p-n junction, functions as the

active component in the optoelectronic devices. The gallium compounds are typically prepared as thin films

by metal organic chemical vapour deposition (MOCVD). Hence, gallium enters the device market in the

form of trimethyl gallium MOCVD precursors.

Zinc oxide (ZnO), an II-VI compound semiconductor, is being investigated as an alternative to GaN in LEDs

and laser diodes. To obtain the p-n junction for the optoelectronically active diode both n-type and p-type

doped ZnO is needed. However, p-type ZnO has limited stability and thus it is not (yet) a feasible

substitute. Similar difficulties obtaining stable p-type compounds restrict the use of other II-VI compounds

such as MgSe and ZnSe. From a component point of view, incandescent light bulbs and fluorescent light

are obvious substitutes for gallium-containing solid state lighting. However, incandescent light bulbs are

being phased out in the EU and other countries, because of their low energy efficiency. Fluorescent lighting

relies on phosphors containing rare earth elements, which are also critical raw materials. Organic LEDs

(OLEDs) are an emerging alternative technology to solid state lighting. OLED displays and light concepts

have been introduced on the market by the major electronics companies. However, for now there are only a

limited number of applications, because current OLEDs are not competitive with solid state LEDs on price

and long-term durability. It is expected that for at least the coming 5-10 years OLEDs will remain a relative

niche compared to solid state lighting.

Stacks of GaAs, (Al)InGaP/As films make so-called multijunction solar cells, which are the only solar cell

types with conversion efficiency of more than 30%. Combined with a high temperature and radiation

resistance they are very high performance solar cells. However gallium-based solar cells are considerably

more expensive than other solar cell types, restricting their use to special applications, such as satellites

and concentrated solar power.15 As a consequence the possibilities for substitution by other solar cell types,

such as established silicon based solar cells, are limited without a significant loss in performance. Of the

emerging second and third generation solar cell technologies copper-indium-gallium-diselenide (CIGS) thin

film solar cells are potential substitutes, because of their radiation resistance and tolerance toward defects.

However, the conversion efficiency is lower and they also contain critical metals gallium and indium.

Material substitution by other III-V or II-VI semiconductor compounds suffers from the same limitations as

described for LEDs.

CIGS thin film solar cells are a growing application that is forecasted to attain a significant share (20%) of

the fast growing photovoltaic market in the coming decades. As a thin film solar technology it holds the

potential of lower manufacturing costs and better product integration compared to the state-of-the-art silicon

wafer based solar modules. CIGS solar modules are manufactured on an industrial scale by around five

companies world-wide. The industrial and academic CIGS community is aware of the criticality of gallium,

but opinions on the need for substitution vary. A one-to-one material substitution by copper-zinc-tin-

selenide/sulphide (CZTS) has become a significant R&D theme in the recent years.16 However, with record

conversion efficiency (2013 figures) of only 11.1% compared to 20.4% for CIGS solar cells, commercial

production of CZTS modules is not likely within the coming 10 years. Also due to the strong cost reduction

in the last 3 years established silicon based solar technology is an obvious substitute for CIGS.

In conclusion currently substitution of gallium in optoelectronic devices (LEDs, laser diodes, photodetectors

and solar cells) is limitedly possible and only at a loss of performance.

Summary

Prime examples for the utility of gallium are the use of gallium arsenide (GaAs) integrated circuits for

wireless communication (e.g. smart phones) and of gallium nitride (GaN) in solid state lighting (LED).

Substitution of gallium is limited because, as a minor and relative costly material, gallium is primarily used

in applications where there are no comparable alternatives.

Figure 3: Distribution of end-uses and corresponding substitutability assessment for gallium. The manner



References 1 Royal Society of Chemistry (2013) Gallium - Element information, properties and uses.

http://www.rsc.org/periodic-table/element/31/gallium. Accessed 7 August 2013 2 Jaskula, B. (2013) Gallium, in: U.S. Geological Survey (ed.) Mineral commodity summaries 2013, pp.

58–59 3 Mikolajczak C, Murphy MD (2011) Sustainability of Indium and Gallium In the Face of Emerging

Markets 4 Phipps, G., Mikolajczak, C., Guckes, T. (2008) Indium and Gallium: long-term supply. Renewable

energy focus 9(4), 58–59 5 Greber, J. F. (2000) Gallium and Gallium Compounds, in: Ullmann's Encyclopedia of Industrial

Chemistry, pp. 335–340. Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA 6 Strategic Metal Investments Ltd. (2013) By-Product Metals: The Aluminum-Gallium Relationship Pt. II -

Strategic Metal Report. http://strategic-metal.typepad.com/strategic-metal-report/2013/01/by-product-metals-the-aluminum-gallium-relationship-pt-ii.html. Accessed 7 August 2013






12 DiFrancesco, C., Kramer, D., Jaskula, B. (2012) Gallium: Supply-Demand Statistics, in: U.S. Geological Survey Minerals Information

13 Gold Canyon Resources Inc. Cordero Gallium project. http://www.goldcanyon.ca/s/Cordero_Gallium.asp?ReportID=363062. Accessed 7 August 2013

14 Gielen, A. J. Green Sustainability and Recycling: ISA world, strategic research agenda, 15 Bleiwas, D. (2010) Byproduct mineral commodities used for the production of photovoltaic cells. U.S.

Geological Survey Circular 1365 16 Delbos, S. (2012) Kesterite thin films for photovoltaics: a review. EPJ Photovoltaics 3.

10.1051/epjpv/2012008

6. Germanium

Germanium is a hard and brittle semi-conducting metal discovered in 1886. Its position (IV A) in the

periodic table (C-Si-Ge-Sn-Pb) indicates that it has properties similar to silicon. Germanium was initially

used industrially in transistors due to its semi-conductor properties. It was later on replaced by silicon,

which has better behaviour with respect to temperature. Its semi-conductor properties, however, remain of

strong interest in some high-performance applications such as photovoltaics. It is now mostly used in fibre

optics to increase their refractive index (reduce transmission losses) and in infrared detection/vision due to

its transparency to infrared radiation. Furthermore it is used as a catalyst in organic chemistry.1

Recycled germanium is estimated by USGS to represent about 30% of the worldwide consumption. This

consists of a notable (60%) fraction of germanium being discarded as scrap during the processing of most

optical devices, which can then be recycled.2 Recycling rates for fibre optic scrap are reported as high as

80%.3 As a consequence, about 50% of the germanium metal used for electronic and optic are recycled in

short cycle.

Germanium is not mined as a principal metal but is obtained as a by-product of zinc refining and from fly-

ash of coal-fired power plants.4 Currently, the production of germanium is dominated by China, followed by

the Ukraine and Russia (see Figure 1). The price of germanium reached a very high level in 2011

(1450 US$/kg in 2011; zone refined germanium producer yearend price; see also Figure 2).2. After

decreasing until the middle of 2012, the price of germanium rose back to an even higher level than before

recently within one year (2013).5

Figure 1: Distribution of germanium production6 and corresponding scores of the producing countries in the

Human Development Index (HDI),7 Environmental Performance Index (EPI),8 and World Governance


determining critical raw materials.10 CHN = China; UKR = Ukraine; RUS = Russia.

Figure 2: Germanium price development during 1980 – 2011. The unit value is the value of 1 metric ton (t)

of germanium metal apparent consumption (estimated).11


Germanium is used mainly in three forms12:

Germanium metal: in the area of infrared optics, photovoltaics and other electronic applications

(totalling about 45% of world demand);

Germanium oxides (GeO2): as catalyst for PET production (particularly in Japan), which accounts

for 25% of world use;

Germanium chlorite (GeCl4): for fibre optic production (particularly in the USA), accounting for about

30% of global use.

Fibre Optics

This is considered the major use of germanium worldwide, accounting for 30-50% of use12. Germanium is

used as a doping element in optical fibres, which contain approximately 4% germanium, the rest being

silicon oxide. The function of germanium in optical fibre is to increase its refractive index, helping to contain

the light within the fibre and enabling the transmission of the digital signal. This technology is a strong

enabler of today’s connectivity, forming the backbone of telecommunications and internet systems. Uptake

will continue to increase in line with the current trend to digitally connect final consumers through fibre

optics (Fibre to the Home – FTTH ; Fibre to the Building – FTTB).

As may be expected for such an important application, there is existing research to develop and improve

fibre optic-based data transport which has spawned new fibre technologies: photonic hollow fibre (from

Corning, the main fibre optics producer), fibres with tellurium layers, “OM2” fibres and erbium-doped fibres

that enable optical signal amplification12, some of which (e.g. hollow-fibre) are based on germanium-free

technology.13 Although germanium has been preferred for fibre optic doping, phosphorous-based doping

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(P2O5) can also be used to raise the refractive index of silica, and other doping elements can be used to

decrease this refractive index.14,15

Polymerization catalyst

Germanium dioxide (GeO2) is a catalyst for the polymerisation of polyesters. Production of polyethylene

terephthalate (PET), used for example in plastic bottles, is a major use.2 Polymerization of resins to

produce PET can also be achieved using alternative catalysts. Sb2O3 is a possible alternative and has been

historically used for PET production, in particular in the US. Its potential health effects (“limited evidence of

carcinogenic effects”) is, however, a cause of concern although different organisations have reported that

its use for PET production is safe under normal circumstances.16 Further potential substitutes are antimony

triacetate, an aluminium-based catalyst (identified by Toyobo) and a titanium-based catalyst (but which has

the disadvantage of giving a yellowish colour to PET).1,12

Infrared optics

Germanium, being transparent to infrared radiation, is used to make lenses and window panes for infrared

detectors and cameras, both in the military and the civilian sector. Both the lens and the detection sensor in

which the infrared radiation is converted to electricity typically use germanium. It is thus used in numerous

applications such as surveillance, night vision and satellite systems.1

Zinc selenide can substitute for germanium metal in selected infrared applications, but with lower

performance.2 Tellurium-based glass has also been announced as a potential substitute for infrared-based

applications.

Parts for electrical and solar equipement

In the domain of photovoltaics (PV), germanium is used mostly in high-performance multi-junction cells

(typically III-V cells). Due to high costs, these cells have been historically used in premium applications

where high performance per surface and weight ratio was important, namely the PV panels used in satellite

systems.

With the development of Concentrated Solar PV (CPV) on-ground systems, it becomes possible to use less

PV cells by concentrating the solar rays on a smaller surface through and optical device (e.g. Fresnel lens),

which reduces the pressure on cost. Multi-junction cells used in conjunction with on-ground CPV systems

thus have a potential for future development. Germanium is typically used in the bottom-cell part of triple-

junction PV, for the substrate, base and emitter layers, thanks to its lattice constant, robustness, low cost,

abundance and ease of production. Germanium is very useful in capturing longer wavelengths. Current

triple-junction cells having now reached efficiency levels close to their theoretical maximum (>43%).

Research has developed towards even higher performance through the study of quadruple-layer multi-

junction cells. In terms of substitution, it can be noted that triple-junction and quadruple-junction cells can

also be based on non-germanium materials (e.g. containing InGaP, AlGaInP, InGaAsP, InGaAs

materials).17 This technology is, however, still at the research level.

On the electronic side, the specific SiGe transistors benefit from the low-cost of silicon processing and of

the high-speed switching characteristics of germanium. Reduced energy consumption of SiGe transistors

with respect to silicon-based transistor creates a strong potential for the third generation of mobile phones

with high-speed wireless applications.12 Germanium is also used in high-brightness LEDs.

Silicon can be a less-expensive substitute to germanium in some electronic applications.2 The fact that

such substitution is not yet in place relates to the higher performance achieved when using germanium.

Some metallic compounds can be used for high-frequency electronics and some light-emitting diode

applications.

Others

Other diverse uses of germanium exist, for example: use as an alloying element (0.35%) for tin, or Al-Mg

alloys, to increase their hardness; soldering material (12% Ge / 88% Au) for gold-based dental prosthesis;

luminescent material (red-coloured); photographic and wide-angle lenses; ceramics, with (Na2O/TiO2 or

K2O/Ta2O5; gamma-ray detector Bi2(GeO3)3; bismuth germanate oxide crystals (BGO – Bi4Ge3O12) for

various detection technology (scintillation, tomography, gamma spectroscopy); fluorescent paint (MgGeO3);

superconductors (Nb3Ge); thermocouple and thermoelectricity; medication (diverse uses currently under

investigation); germanium-containing products are sold in the US as antioxidants.

Summary

Germanium material has demonstrated to be well suited for several major applications with comparable

importance (~25-30% of Ge usage): fiber optics, infrared optics and polymer catalysts.

Due to a history of using a germanium-free catalyst for PET production in the USA, the substitution by

Sb2O3 is judged reasonable but suffers from persisting concerns about possible health effects.

Both for fiber-optics and infrared optics, no evidence has been identified of cheap and off-the-shelf

substitution solutions for the breadth of these applications. Possibilities exist, but are overall either

characterized by a likely loss of performance, a lack of industrial maturity (e.g. still at the research level), or

an uncertainties about their ability to fulfil all the requirements of the product/solution or industrialization

capabilities. In the case of fiber-optics, which has nowadays almost a status of a commodity-product, the

production volume puts a specific pressure on the substitution potential. For infrared-optics, although the

use is less wide-spread, the market has been evolving towards wider use (e.g. security, maybe tomorrow

consumer equipment).

For solar applications (photovoltaic, e.g. satellite PV panels) and high-profile electronic applications, it is

judged that the level of requirements justifies the consideration as “premium” applications, where

performance largely dominates cost issues.

Figure 3: Distribution of end-uses10 and corresponding substitutability assessment for germanium. The



References 1 Butterman W.C., Jorgenson JD (2005) Germanium. Open-File Report 2004-1218 2 Guberman, D. E. (2013) Germanium, in: U.S. Geological Survey (ed.) Mineral commodity summaries

2013 3 Bell Labs - Lucent Technology Bell Labs Innovative Germanium-Recovery Process is Economically,

Environmentally Friendly. Science Daily. http://www.sciencedaily.com/releases/1997/10/971023172421.htm. Accessed 23 August 2013

4 Willis P, Chapman A, Fryer A (2012) Study on by-products of copper, lead, zinc and nickel 5 Metal Bulletin Germanium Metal Rotterdam $/kg: Latest Metal Prices Tracking and Comparison Tool.

http://www.metalbulletin.com/My-price-book.html?price=42087. Accessed 3 September 2013 6 Reichl C, Schatz M, Zsak G (2013) World Mining Data: Production of Mineral Raw Materials of

individual Countries, by Minerals. in 2011 in metric tonnes 7 United Nations Development Programme (UNDP) (2013) The 2013 Human Development Report –




European Commission 11 Kelly, T., George, M., Jasinski, S., Gabby, P., Guberman, D. (2012) Germanium: Supply-Demand

Statistics, in: U.S. Geological Survey Minerals Information 12 Christmann P, Angel JBL, Barthelemy F, Benhamou G, Billa M, Gentilhomme P, Hocquard C, Maldan

F, Martel-Jantin B, Monthel J (2011) Panorama du marche 2011 de germanium Rapport Final. BRGM/RP-60584-FR

13 Amezcua Correa R (2009) Development of hollow-core photonic bandgap fibre free of surface modes. Ph.D. thesis. Southampton

14 Brown, T. G. (1995) Optical Fibers and Fiber-Optic Communications, in: Bass M (ed.) Handbook of optics, 2nd edn., pp. 10.1-10.50. New York: McGraw-Hill

15 CEA internal. Personal communications 16 International Antimony Association (2012) Antimony trioxide.

http://www.antimony.com/files/cms1/publications/i2a-factsheet-trioxyde-v3.pdf. Accessed 30 August 2013

17 Luque A, Hegedus S (2011) Handbook of photovoltaic science and engineering, 2nd edn. Chichester: Wiley

7. Natural graphite

Natural graphite is a form of carbon where atoms are arranged in layers that have weak bonds between

each other. The particular layered structure of graphite makes it one of the most stable and unreactive

materials. Graphite also retains its strength and physical properties at temperatures in excess of 2200 ºC.

The weak bond between layers causes graphite to be soft and slippery, resulting in a high natural lubricity.

This layered structure can be modified by techniques such as intercalation where atoms of another element

are incorporated between the layers to achieve certain properties such as superconductivity, or

impregnation, where graphite is infused with other materials to achieve similar results as intercalation.1

Natural graphite is mined in three qualities: vein, flake and microcrystalline (often referred to as amorphous

graphite), with different uses.2 Mines can be either open pit or underground.3 Current supply of natural

graphite is dominated by Chinese producers. Synthetic graphite is concentrated in countries/regions such

as USA, Europe and Japan. Because of higher production cost and process knowledge, the graphite

market is still dominated by natural graphite.

Figure 1: Distribution of natural graphite production4 and corresponding scores of the producing countries in

the Human Development Index (HDI)5, Environmental Performance Index (EPI)6, and World Governance


determining critical raw materials.8 CHN = China; IND = India; BRA = Brazil.

After a short decreasing period down to a price of natural graphite of 0.69 US$/kg in 2009, the price of

natural graphite increased up to a value of 1.18 US$/kg in 2011.9 These prices do represent the monetary

values of the quality flake. Amorphous was five times cheaper (on average) than flake natural graphite

during 2008 to 2011.

Figure 2: Natural graphite price development during 1980 – 2011. The unit value is defined as the value of

1 ton (t) of natural graphite in current dollars (estimated).10


Steel Industry

The steel industry represents a 24% share of natural graphite consumption. In this industry, graphite (both

natural and synthetic) is used for its high temperature stability, thermal shock resistance, chemical

inertness and ability to withstand corrosion. Natural graphite is used as a refractory liner for furnaces, ladles

and crucibles in the continuous casting of steel and as an agent to increase the carbon content of steel.11

Natural graphite can be substituted in the steel industry (increasing the carbon content of steel) by use of

manufactured graphite powder, scrap from discarded machine shapes, and calcined petroleum coke.3,9.

Foundries

Foundries (factories that produce metal castings) account for a further 24% of the share of natural graphite

use. Graphite is used in blocks that form the lining of the blast furnace due to its high temperature stability

(refractory). Graphite is ideal because it is highly unreactive and resistant to acids, alkalis and other

chemical substances.11 In principle, natural graphite can be substituted for manufactured graphite powder

and calcined petroleum coke.3,9

Crucible production

Graphite is the main component in the manufacture of crucibles, and 15% of natural graphite is consumed

in this industry alone. Natural graphite is the preferred material due to its corrosion resistance, thermal

shock resistance and oxidation resistance capacity. Graphite can be substituted by silicon carbide1,

however, it does have better properties than alternatives.

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Electrical applications

A share of 12% of the consumption of natural graphite is attributed to electrical applications. Most important

are the manufacture of carbon brushes in electric motors, where graphite is preferred due to its high

stability.1 In many cases natural graphite can be substituted by synthetic graphite.3

Refractories

The refractory industry consumes 8% of natural graphite. Due to graphite’s high temperature stability,

thermal shock resistance and chemical inertness, graphite is ideal for use as a component in bricks that

line furnaces such as oxygen furnace, electric arc furnace and blast furnaces.1 Silicon carbide can be used

as a substitute for graphite in refractory applications.12 Moreover, zirconia and SiAlON are potential

alternatives. Synthetic graphite does not compete with natural graphite in refractories.13

Lubricants

Graphite possesses exceptional lubricating properties, which make it highly suitable for use in lubricants.

This application accounts for 5% of total natural graphite use, in the form of graphite powder. Its

applications include the use in heavy machinery to reduce friction between parts where high temperatures

prevail, such as in sliding bearings, piston rings, guide bearings and steam joint rings, sliding and sealing

rings for mechanical seals, vacuum pumps, compressor and pumps.1. Natural graphite can be substituted

by synthetic graphite or by molybdenum disulfide (but the latter is prone to oxidation).3,12

Pencils

Pencils, although traditionally known as “lead” pencils, contain nontoxic microcrystalline (“amorphous”)

natural graphite mixed with clay. Graphite is suitable for this application because the weakly held layers of

carbon atoms slide easily over each other and allow for a black streak to be left on paper.14 Substitutes for

pencils include the use of pens and ink as well as coloured pigments or charcoal.

Batteries

Batteries account for 4% of natural graphite consumption. Here graphite (both natural and synthetic) is

used for anodes due to its electrical conductivity.1,3 An alternative to graphite anodes for lithium-ion

batteries has been developed (with improved properties); the production technology is currently at the pilot

stage.15

Summary

In principle, it is possible to substitute natural graphite by either its synthetic alternative (e.g. in batteries or

for increasing the carbon content of steel), by replacing the product as in the case of pencils, by other

compounds as in high temperature applications (e.g. refractories). In the latter case, it is difficult to fully

substitute graphite while retaining the same level of performance.

Figure 3: Distribution of end-uses and corresponding substitutability assessment for graphite. The manner



References 1 Graphite Stocks (2013) How Graphite is Used. http://www.graphitestocks.com/how-graphite-is-

used.php/. Accessed 26 June 2013 2 Frohs, W., Sturm, F. von, Wege, E., Nutsch, G., Handl, W. (2010) Carbon, 3. Graphite, in: Ullmann's

Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA 3 Jäger, H., Frohs, W., Banek, M., Christ, M., Daimer, J., Fendt, F., Friedrich, C., Gojny, F., Hiltmann, F.,

Meyer zu Reckendorf, R., Montminy, J., Ostermann, H., Müller, N., Wimmer, K., Sturm, F. von, Wege, E., Roussel, K., Handl, W. (2010) Carbon, 4. Industrial Carbons, in: Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA






9 Olson, D. W. (2013) Graphite, in: U.S. Geological Survey (ed.) Mineral Commodity Summaries 2013, pp. 68–69

10 Sznopek, J., Olson, D. (2012) Graphite: Supply-Demand Statistics, in: U.S. Geological Survey Minerals Information

11 The A to Z of Materials (2013) Graphite (C) – Classifications, Properties and Applications of Graphite. http://www.azom.com/article.aspx?ArticleID=1630. Accessed 26 June 2013

12 Kogel J, Trivedi N, Barker J (2006) Industrial Minerals and Rocks: Commodities, Markets, and Users. 13 Diniz V (2013) What is Synthetic Graphite? Asbury Carbon's Stephen Riddle Explains.

http://resourceinvestingnews.com/50143-what-is-synthetic-graphite-asbury-carbons-stephen-riddle-explains.html. Accessed 31 August 2013

14 Preserve Articles (2013) What are the Essentials properties and uses of Graphite? http://www.preservearticles.com/201012291918/properties-and-uses-of-graphite.html. Accessed 26 June 2013

15 Nexeon (2013) Unique silicon anode technology for the next generation of lithium-ion batteries. http://www.nexeon.co.uk/. Accessed 31 August 2013

8. Indium

Indium is a silvery-white metal that is chemically and physically similar to gallium and thallium (all in Group

III of the periodic table). With a melting point of 157 °C, indium belongs to a group of low melting point post-

transition metals that are very soft and malleable. A particular concern for indium criticality is its main use in

growing and emerging markets. Indium is exclusively used in electronics applications that have grown and

are forecasted to continue to grow at high rates of 5 – 30% per year1–3. A prime example is the use of

indium doped tin oxide (ITO) in flat panel displays (LCD, plasma screens, e-paper), which constitute the

major use (75%) of indium4. The demand for flat panel displays quickly accelerated due to increasing use of

flat screen televisions, PC monitors, notebooks and tablets and mobile phones. At the same time organic

electronics, such as active-matrix organic light-emitting diode (AMOLED) displays, organic light-emitting

diode (OLED) lighting and photovoltaics, also using ITO, and thin film CuInGaSe2 (CIGS) photovoltaics are

emerging technologies forecasted to also grow quickly in the coming decade1,3,5. However, there is a

significant awareness of the indium criticality in the electronics industry and considerable academic and

industrial effort is put into the development of substitutes for indium6. The price of indium represents this

fact in one dimension as well, since the price was already high and even increased to an annual average

value of 720 US$/kg in 2011*.4 The price decreased in the year 2011 and then was stable above 500US$

per kg in 2012. In 2013 the price started to increase again.7

Figure 1: Distribution of indium production8 and corresponding scores of the producing countries in the



determining critical raw materials12. CHN = China; CAN = Canada; KOR = South Korea; JPN = Japan.

Indium is mainly obtained as a by-product from zinc concentrates. While China is the largest producer

worldwide, there is also significant production in Canada, Korea and Japan. Since 2012, primary production

has increased both in China and in the rest of the world, including Europe. This has enabled the Western

* New York dealer: Price is based on 99.99%-minimum-purity indium at warehouse (Rotterdam); cost, insurance, and freight (in minimum lots of 50 kilograms).

world to supply an increasing share of its demand, while China’s exports have decreased and they have

been stockpiling some of their output (without a noticeable price effect). Forecasts of growth for future

indium applications have also been considerably reduced as the CIG (copper-indium-gallium) technology

has failed to become a competitive alternative for PV applications.13

Figure 2: Indium price development during 1980 – 2011. The unit value is the value, in current dollars, of 1

metric ton (t) of indium apparent consumption (estimated).14


The uses of indium can be grouped into three types of indium compounds15:

Indium-tin-oxide (ITO) thin films for

o Flat panel displays

o Optoelectronic windows (architectural glass / windscreens)

Indium compounds (III-V semiconductors) for

o LEDs

o Integrated circuits

o Thin film CuInGaSe2 (CIGS) solar cells

Alloys for

o Low-melting point solders

o Dental alloys

o Surface coatings

o Minor alloys

Flat panel displays

The major use of indium is found in thin film indium-tin-oxide (ITO) windows for flat panel displays2,4.

Television screens, PC monitors, notebook screens and touchscreens on mobile phones and tablets all

require a window that is electrical conducting and optically transparent16. The electrical conductivity

facilitates the voltage-triggered switching of the pixels in a display. ITO is a transparent conductive oxide

(TCO) that combines a good conductivity with a high optical transparency. In addition ITO has a high

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atmospheric stability, i.e. durability, and allows accurate etching of the electrode arrays used to address

individual pixels. ITO consists of 90% In2O3 and 10% SnO2 corresponding to a 75 wt% indium content. It is

supplied to the flat panel display manufacturing industry as ITO targets for sputter tools. In manufacturing

the in-line sputter tools deposit thin (100 nm) ITO films at high rates on large area display glass panels.

The flat panel display industry is aware of the criticality and the associated price fluctuations of indium.

Considerable R&D effort has been and continues to be focused on finding alternatives for ITO6. Other

TCOs, in particular aluminium doped zinc oxide (AZO) and fluorine doped tin oxide (FTO) are possible

substitutes for ITO. Both are produced on an industrial scale and at lower cost than ITO. However, in

performance both AZO and FTO lags behind ITO. The specific conductivity is respectively a factor of 2 and

4 lower requiring thicker films for a similar electrical performance, which reduces the transparency of the

screen. Also AZO and FTO cannot be etched as accurately as ITO, preventing their use in high resolution

displays, like the latest generation of mobile phone touchscreens. Finally, AZO is sensitive to degradation

by moisture. Emerging amorphous TCOs, like gallium-indium-zinc-oxide (IGZO / IZGO), indium-zinc-oxide

(IZO) and zinc-tin-oxide promise properties equal or better than ITO, but are estimated to take at least 5

years to commercialisation. Moreover, although the concentration is lower IGZO and IZO still contain

indium.

Next to the TCOs there is a range of transparent conductive film technologies under development with an

estimated time-to-market of 5 – 10 years, in particular:

Ultrathin metal films and zinc oxide-metal-zinc oxide multilayers

Carbon nanotubes and metal nanowire films

Graphene films

Organic transparent conductors (PEDOT:PSS)

Printed metal grids

All these alternatives under perform on at least one of the properties required for flat panel display

application. Apart from the multilayers and the metal grids that outperform ITO, these alternatives do not

(yet) exhibit the same good electrical conductivity at a high optical transparency as ITO. The ability to etch

the films and the durability of the films needs to be established. The viability of manufacturing on industrial

scale at competitive costs still has to be proven for all these technologies.

Research and development into display technologies that do not require ITO started form the emerging

field of flexible electronics, like organic LED (OLED) displays on foil. Here the low mechanical stability of

ITO, which restricts display flexibility, presents an additional driver for finding alternatives to ITO. An

organic transparent conductive PEDOT:PSS with a printed silver grid is able to substitute ITO in prototype

flexible OLED displays. However, their limited durability has prevented commercialization of ITO-free

flexible displays up to now. Active-matrix OLED displays on glass have been introduced in the mobile

phones market recently, but these rigid displays use ITO. The only alternative ITO-free display technology

available today is LED displays, as used in LED television screens, signage and billboards. LED displays

do not need transparent electrodes because individual LED pixels are addressed form the display backs-

side. However, indium-gallium-nitride-based diodes are the main active components in LED displays.

In conclusion, substitution of flat panel displays containing ITO, either by an ITO alternative or a different

display technology, is currently not possible without a loss of performance or the use of another indium

containing component.

Optoelectronic windows

In addition to flat panel displays, another range of applications uses ITO on glass to obtain specific

optoelectronic functionalities. The combination of electrical conductivity with a high optical transparency of

ITO is used to add an electrical function to glass with a minimum loss in transparency. Also in

optoelectronic applications indium is procured as ITO targets for thin film ITO film sputtering.

The main optoelectronic window application is architectural glass16. Low-emissivity coatings containing ITO

reduce heat losses through windows. In these coatings ITO is part of a multilayer stack including

transparent silver films and various atmospheric barriers and adhesion layers. An emerging application in

architecture is smart windows that allow light balancing, temperature regulation by IR reflection and

integration of transparent sensors. Light balancing is, for example, achieved by controlling the light

transmission through an electrochromic film containing ITO. Similar ITO coated smart windows are

gradually entering the automotive market. Currently, some cars are equipped with defogging windscreens

and defrosting headlights through heating of a resistive ITO coating.

Fluorine-doped tin oxide (FTO) is a substitute for ITO in architectural glass. FTO is applied in-line

immediately after glass production in float glass lines. The lower specific conductivity of FTO compared to

ITO is not an issue because a low conductivity is required for low-emissivity coatings16. Also FTO has a

similar high resistance to atmospheric degradation as ITO. In well-packaged low-emissivity multilayers,

such as inside double glazing, zinc oxide and aluminium-doped zinc oxide (AZO) are also a feasible

substitutes for ITO. The packaging protects the zinc oxide against degradation by moisture from the

atmosphere. Heated windscreens and headlights require higher conductivities making FTO and AZO less

suitable substitutes. Additionally, the sensitivity of AZO to atmospheric degradation excludes its use in

these applications. Emerging amorphous TCOs, like gallium-indium-zinc-oxide (GIZO / IZGO), indium-zinc-

oxide (IZO) and zinc-tin-oxide promise properties equal or better than ITO, but are estimated to take at

least 5 years to commercialisation. Moreover, GIZO and IZO still contain indium, although the concentration

is lower.

A growing application of optoelectronic windows is thin film solar cells. Highly conductive and transparent

windows are needed to let sunlight enter the solar cells and transport the generated current away. ITO has

been used a window layer in the so-called second generation solar cells, based on thin film cadmium

telluride (CdTe), amorphous silicon (aSi) and copper-indium-gallium-diselenide (CIGS). However, FTO or

AZO are now state-of-the-art in industrial manufacturing of these thin film solar cells. For the third

generation solar cells, organic solar cells (OPV) and dye-sensitized solar cells (DSSC) that are forecasted

to be commercialized in 5 to 10 years, ITO is the preferred window material. The chemical aggressiveness

of the electrolyte used in DSSC makes replacement of ITO impossible for now. Just as for the flat panel

OLED displays, organic transparent conductive PEDOT:PSS with a printed silver grid are able to substitute

ITO in OPV, in particular for flexible modules.

In conclusion, substitution of ITO in optoelectronic windows is currently possible for architectural windows,

but this is not possible without a loss of performance for heated windscreens and car lights. For current thin

film solar cells technologies ITO alternatives are already in place and for next generation solar cells ITO

substitution will be possible.

Low melting point alloys

Indium has one of the lowest melting points of all metals and forms low melting point (i.e. room temperature

to 156 °C) alloys with tin, silver, lead and ternary or quaternary combinations thereof. Indium alloys are

therefore used in the electronics industry for soldering on temperature sensitive materials in moulded

interconnect devices, flexible printed circuit boards or of temperature sensitive components in photonic

applications, e.g. bonding of LEDs. Indium-lead is used for soldering on gold bond pads on printed circuit

boards (PCBs) because of the better durability compared to tin-based alloys. Indium alloys are also highly

ductile even at very low temperatures and are used to bond materials, (such as, quartz, glass and

ceramics) with a large thermal expansion mismatch and in sealing of cryogenic equipment (e.g. liquefied

gas production). Finally, indium is used to reduce mercury leakage in dental filling amalgams. Little effort

has been put into finding alternatives for indium alloys, because they are used in relatively niche

applications.

There is range of tin-based alloys with zinc and bismuth used extensively for soldering and bonding in the

electronics industry. However, tin-alloys have melting points down to 150 °C, which is the maximum in the

melting point range of indium alloys. Lead-based alloys enable lower melting point, but these have recently

been banned by the EU in the RoHS (Restriction of Hazardous Substances) directive. Hence, only for the

least thermally sensitive applications are tin-based alloys good substitutes for indium alloys. Tin-alloys can

also be used for bonding on gold, but indium alloys were specially developed as an alternative to the tin-

alloys. The so-called gold scavenging by bonding alloys resulting in destruction and failure of gold bond

pads is much lower for indium alloys than for tin alloys. Substitution of indium alloys in cryogenic sealings

by tin-based alloys is not possible, because tin alloys lose their ductility at low temperature.

Alternative bonding/soldering technologies to metal alloys have been developed as part of the search for

lead-free solders in the last decade. Silver-filled conductive adhesives have found limited industrial use,

because of the high costs associated with the silver-filling. Nanoparticle pastes, using the melting point

reduction of materials on the nano-scale are an emerging alternative bonding technology, but still have a

time-to-market of at least 5 – 10 years. In general, market introduction of alternative bonding technologies

is hindered by the huge installed base of soldering equipment and the strong focus on low-cost and high

reliability manufacturing in the electronics industry.

Indium-free dental fillings are widely used. Indium was specially introduced in dental filling amalgams to

increase strength and reduce mercury leakage. Gallium based amalgams have also been developed, but

are not preferred due to the criticality of gallium. Composite resin dental fillings are a general alternative to

amalgam dental fillings. Although the durability of the composite fillings is marginally less, costs are slightly

higher and application less easy composite dental fillings are a suitable alternative17.

In conclusion substitution of indium alloys is currently possible in dental alloys, is possible for a number of

low temperature bonding and soldering applications, but is not possible for cryogenic sealing.

In-compounds

Indium-containing semiconductors are currently a minor use of indium. Semiconductor compounds of

indium, specifically InP are used in high-power and high-frequency electronics, for example high tech

mobile phones and wireless applications. Optoelectronics devices such as laser diodes, photodiodes and

LEDs use InP, InGaAs and GaInN because of their high electron velocity compared to silicon and their

direct bandgap. The In-based semiconductors are part of the multilayer stacks used as the active

component in LEDs and laser diodes. GaAs and SiGe are alternatives to InP exhibiting similar properties

http://en.wikipedia.org/wiki/Optoelectronics

http://en.wikipedia.org/wiki/Laser_diode

http://en.wikipedia.org/wiki/Electron_velocity

http://en.wikipedia.org/wiki/Direct_bandgap

required for the high high-power and high-frequency electronics. However, both use other critical raw

materials such as Ge and Ga. Zinc oxide (ZnO) has been investigated as an alternative semiconductor

material in LEDs. However, the required p-type ZnO has limited stability making in not (yet) a feasible

substitute. OLEDs are an emerging alternative lighting technology, but still lack the long-term stability to

compete with solid state LEDs.

Copper-indium-gallium-diselenide (CIGS) thin film solar cells are a growing application that is forecasted to

attain a significant share (20%) of the fast growing photovoltaic market in the coming decades. CIGS is an

III-IV-VI semiconductor with a band-gap ideal for conversion of sun light into electricity and, as a thin film

solar technology, it holds the potential of lower manufacturing costs and better product integration

compared to the state-of-the-art silicon wafer based solar modules. CIGS solar modules are manufactured

on an industrial scale by around five companies world-wide. The industrial and academic CIGS community

is aware of the criticality of indium, but opinions on the need for substitution vary. A one-to-one material

substitution by copper-zinc-tin-selenide/sulphide (CZTS) has become a significant R&D theme in the recent

years18. However, with a record efficiency (2013 figures) of only 11.1% compared to 20.4% for CIGS solar

cells, commercial production of CZTS modules is not expected within the coming 10 years. Also due to the

strong cost reduction in the last 3 years, silicon based solar modules are an obvious substitute for CIGS

apart from its limitation of integration in electronic devices and the build environment.

In conclusion, substitution of indium is at present mostly possible in semiconductor applications (high-

power and high-frequency electronics applications and thin film solar cells) with the exceptions of

optoelectronic devices (LEDs and laser diodes).

Summary

Indium cannot be substituted in its main field of application, flat panel displays, without a loss of

performance or the use of another indium containing component, but substitution is possible in most other

applications albeit sometimes at higher costs.

Figure 3: Distribution of end-uses and corresponding substitutability assessment for indium. The manner



References

1 Mikolajczak C, Murphy MD (2011) Sustainability of Indium and Gallium In the Face of Emerging

Markets

2 POLINARES Consortium (2012) Fact Sheet: Indium: POLINARES working paper n. 39

3 Phipps, G., Mikolajczak, C., Guckes, T. (2008) Indium and Gallium: long-term supply. Renewable

energy focus 9(4), 58–59

4 Tolcin, A. C. (2013) Indium, in: U.S. Geological Survey (ed.) Mineral commodity summaries 2013, pp.

74–75

5 Bleiwas, D. (2010) Byproduct mineral commodities used for the production of photovoltaic cells. U.S.

Geological Survey Circular 1365

6 NanoMarkets (2012) Transparent Conductor Markets 2012: REPORT # Nano-559.

http://nanomarkets.net/market_reports/report/transparent_conductor_markets_2012. Accessed 7

August 2013

7 Metal Bulletin Indium Ingots MB free market Monthly Average in warehouse $ per kg: Latest Metal

Prices Tracking and Comparison Tool. http://www.metalbulletin.com/My-price-book.html. Accessed 3

September 2013

8 U.S. Geological Survey (2013) Mineral Commodity Summaries 2013








European Commission

13 Mikolajczak C (2014) Indium supply and demand. E-Mail. Accessed 3 December 2014

14 DiFrancesco, C., George, M., Carlin, J., Jr., Tolcin, A. (2012) Indium: Supply-Demand Statistics, in:

U.S. Geological Survey Minerals Information

15 O'Neill B (2010) Indium Market Forces: A Commercial Perspective

16 Szyszka, B. (2011) Übersicht über die Einsatzgebiete und Anwendungen von TCOs, in: OTTI (ed.)

Transparent leitfähige Schichten (TCO), pp. 81–124

17 Bharti, R., Wadhwani, K., Tikku, A., Chandra, A. (2010) Dental amalgam: An update. J Conserv Dent

13(4), 204–208. 10.4103/0972-0707.73380

18 Delbos, S. (2012) Kesterite thin films for photovoltaics: a review. EPJ Photovoltaics 3.

10.1051/epjpv/2012008

9. Magnesium

Magnesium is the lightest structural metal. During the last decade, magnesium production in China has

increased enormously. China's production was 250 000 Metric tons in 2002 and 675 000 Metric tons

annually in 2011.1 This supply increase resulted in lower prices, leading to the closure of magnesium plants

in the rest of the world. The last primary producer in Western Europe closed in 2002. There have been

plans to start magnesium production in Europe over the past ten years, but continuing low prices have

made it difficult to create a business case for it. Therefore, the production of magnesium is currently

concentrated mainly in China.

Figure 1: Distribution of magnesium production2 and corresponding scores of the producing countries in the




After a price peak in 2009 the average price of magnesium metal has fallen down again. The average price

of magnesium metal was 0.97 US$/kg in 2011*, a decline of 33% since 2009.2 Looking at a longer time

frame from 2005 to 2012 it appears that the price is rising overall. During the period from 2011 and 2012

the price was stable and then started to decrease at the beginning of 2013.7 In Europe, Magnesium is

mainly used in 3 different product categories; pure magnesium (>99,8% GHT) for aluminium alloying,

magnesium alloys (<99,8% GHT) and as powder for metal desulphurization.8

* U.S. spot Western

Figure 2: Magnesium metal price development during 1980 – 2011. The unit value is the value in dollars of

1 metric ton (t) of magnesium metal apparent consumption (estimated)9.

Aluminium alloys

Magnesium as alloying element is most relevant for 5000 and is essential for 2000, 6000 and 7000 series

aluminium alloys as it is involved in the precipitation hardening process even if some of these alloys contain

typically less than 1% magnesium. 3104 alloy used for beverage can body contains 1% of magnesium and

represent a significant volume of aluminium alloys.8,10

The presence of magnesium as the main alloying element in the 5000 series (used up to 6 wt %) leads to

solute hardening of the alloy, and efficient strain hardening, resulting in medium strength. The good

formability, combined with the medium strength, excellent corrosion resistance, high quality anodising

ability as well as weldability, result in many applications for outdoor exposure: in construction sheet (for

example in anodised and electrocoloured facade panels), scaffolding, and in particular in marine

applications (ship building, platforms, etc) and in packaging (food cans, beverage cans, easy open lid both

for aluminium and steel cans). In automotive applications, 5000 series alloys are also used for press

formed body-parts and chassis components due to their good combination of strength and formability.

Three different strategies can be identified for substituting magnesium in aluminium alloys or the aluminium

alloys themselves: use of other elements in the same alloy series, use of a different aluminium alloy series

or the use of other materials altogether. Substitution of Mg with iron in aluminium alloys will give a

hardening effect. But adding iron to the alloy leads to a deterioration of the corrosion properties of

aluminium. This is a particular drawback when aluminium is used in shipbuilding.

5000 series aluminium alloys can in some cases be substituted by 3000 series alloys. The 3000 series

alloys have manganese (range 1–2 wt %) as the main alloying element. Manganese makes the alloys

ductile, resulting in good formability while still allowing a wide range of mechanical properties through

various strain hardened tempers. The 3000 series are medium strength alloys and are at present

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predominantly found in heat exchangers in automotives and power plants11. Substitution of 5000 series with

3000 series in areas like construction and transportation will therefore be at the cost of the material

strength. As the manganese used for alloying aluminium is pure manganese produced by electrolysis

(production located primarily in China), the substitution by 3000 series alloys is only a theoretical and not a

practical solution.8

Steel can be used as a substitute for aluminium in packaging (beverage cans body but not lid),

construction and transportation (automotive). The development of ultra high strength steels has resulted

in steel alloys with a strength-to-weight ratio close to that of aluminium.

Advanced polymers can substitute aluminium alloys, like the use of carbon fibre-reinforced polymer in

aircraft instead of 7000 series alloys.

Casting alloys

Magnesium alloys are typically used as cast alloys for many components of modern cars, and hybrid

magnesium/aluminium block engines have been used in some high-performance vehicles. The average

content in automobiles is around 5kg, with some models using more that 30 kg of magnesium alloys.8 Die-

cast magnesium is also used for camera bodies, portable computers and housings and components in

lenses.

Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these

alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like

aluminium, copper and steel. It is therefore very difficult to forge the materials.

Polymer (e.g. acrylonitrile butadiene styrene ABS) injected moulded parts are a direct competitor to cast

magnesium parts. Aluminium cast and forged parts can also compete with magnesium in several

applications but at the cost of a higher weight of the part.

Wrought Alloys

Magnesium is seldom used as wrought alloy because of the poor formability. There are, however, specialist

niche applications in the printing industry and military applications; extruded magnesium bars, sections and

tubes are used in aerospace, nuclear and other engineering applications.8 In these applications, age-

hardened wrought aluminium alloys are a suitable substitute, although there is a weight increase.

Summary

Magnesium can be substituted in most applications at some extra cost or through a loss of performance

with options already available today. The largest perceived performance loss is seen for casting alloys. The

substitution of magnesium in aluminium alloys (substance for substance) is very challenging and leads to a

deterioration of other properties like corrosion properties and a rise in costs.

Figure 3: Distribution of end-uses and corresponding substitutability assessment for magnesium. The



References

1 Kramer, D. A. (2012) Magnesium, in: U.S. Geological Survey (ed.) 2011 Minerals Yearbook: Volume I -

Metals and Minerals, pp. 45.1-45.10

2 Kramer, D. A. (2013) Magnesium metal, in: U.S. Geological Survey (ed.) Mineral Commodity

Summaries 2013, pp. 96–97. Reston, VA








European Commission

7 Metal Bulletin Magnesium MB free market min $ per tonne: Latest Metal Prices Tracking and

Comparison Tool. http://www.metalbulletin.com/My-price-book.html. Accessed 3 September 2013

8 CRM Alliance (2015) Input for CRM_InnoNet Magnesium Profile. E-Mail

9 DiFrancesco, C., Kramer, D. (2012) Magnesium Metal: Supply-Demand Statistics, in: U.S. Geological

Survey (ed.) Minerals Information

10 Hatch JE (1984) Aluminum: Properties and Physical Metallurgy

11 ESAP Welding & Cutting United States (2013) Understanding the Aluminum Alloy Designation System.

http://www.esabna.com/us/en/education/knowledge/qa/-Understanding-the-Aluminum-Alloy-

Designation-System.cfm. Accessed 7 August 2013

10. Niobium

Niobium is one of the five major refractory elements with very high resistance to corrosion. It is an element

in Group VA of the periodic table and has a body-centered cubic (BCC) crystal structure. Niobium is used

as an alloying element in carbon and alloy steels as well as in non-ferrous metals to increase strength and

improve temperature and corrosion resistance. Due to these properties as well as good cold formability and

weldability, niobium-containing alloys are used in jet engines and rockets, chemical instrumentation

technology, nuclear power engineering and in oil and gas pipelines where niobium allows for the extreme

pressures.1 Niobium has superconductive properties and thus is used in superconductive magnets which

preserve their properties in strong magnetic fields.2 The main uses of niobium can be identified as: High

strength low alloy (HSLA) steel, stainless steel, super-alloys and superconducting NbTi alloy magnets.3

Ferroniobium, (66% niobium 34% iron) represents over 90% of world niobium production.4 Mine production

of niobium is clearly dominated by Brazil, with Canada contributing a minor share of world niobium supply.

Global niobium demand has grown at 10% annual growth rate over the last 10 years.4 Niobium is not

traded on any metal exchange and, therefore, there are no “official” prices for niobium. The current price of

ferroniobium is estimated to be around 40 US$/kg but the tendency has been slightly decreasing in recent

months.5

Figure 1: Distribution of niobium production6 and corresponding scores of the producing countries in the



determining critical raw materials.10 BRA = Brazil; CAN = Canada.


HSLA steels

Niobium-containing HSLA steels are mainly used in:

- Construction: Used for lightweight structures that require additional strength and corrosion

resistance and as high strength reinforcing bars with good weldability.

- Automotive & shipbuilding: Used in order to improve fuel efficiency through weight reduction.

- Oil & gas pipelines: Used due to their superior ability to withstand increased pressure and volumes

over greater distances.

Vanadium and molybdenum can be used as substitutes for niobium when material strengthening and

refractory properties are required.11 However, cost and performance penalties can be expected due to the

following reasons:

- Niobium prices are lower and much more stable than these substitutes12,

- Almost twice as much vanadium has to be used to achieve the same strengthening results niobium

does,

- Niobium is the lightest of the refractory metals,

- Niobium is unique in that it can be worked through annealing to achieve a wide range of strength

and elasticity.

The last reason makes it extremely difficult to substitute niobium-containing HSLA steels in oil & gas

pipelines, which is enforced due to the need to transport gas long distances under high pressure requires

steel pipes with greater toughness to prevent fractures.13

Stainless Steels

About 3% of worldwide annual niobium demand accounts for production of stainless steel grades3 where

niobium improves high temperature behaviour and corrosion resistance and strengthens the material.

Molybdenum, titanium and tantalum can substitute niobium in these materials, however this can result in

some cost increase.

High-nitrogen stainless steels can be a reasonable substitute for niobium-containing steels in many

applications due to their high strength combined with high ductility, improved corrosion resistance and

increased high temperature tensile strength.

Super-alloys

The unique ways that niobium enhances the properties of super-alloys make them premier materials of

choice in today’s aerospace and land-based gas turbines.14 These alloys are developed for elevated

temperature service, where severe mechanical stress is encountered and high surface integrity is usually

required. They combine high tensile strength and ductility, rupture and creep strength with inherent stability

and favourable low-cycle fatigue properties.

Tantalum, molybdenum and tungsten can substitute niobium in these materials to some extent. Another

opportunity that appears more attractive is the substitution of super-alloys by ceramic materials in this

application. Ceramics are lightweight, strong, and heat-resistant, but have a reputation for being brittle

materials that shatter on impact and thus do not meet strict criteria for materials intended for gas turbine

service. However, ceramic matrix composites (CMCs) made from a silicon carbide/nitride matrix toughened

with coated silicon carbide fibers embedded in the matrix are durable, withstand temperatures as high as

1300 °C and weigh one-third of niobium-containing super-alloys. In September 2010 GE reported that the

company for the first time has been able to make CMC rotating parts and test CMCs-based turbine blades.

In February 2012, IHI, a leading aircraft engine manufacturer in Japan, announced in a press release that

they would finalize mass-production technology of CMC parts for jet engines in 2015, aiming for

commercialization of CMC parts in 2020.15 CMCs appear to be very attractive substitutes for super-alloys

as they are strong, tough and can be mass produced. If CMCs parts substitute super-alloys in gas turbines,

their engines will become 15% more efficient due to the weight reduction.16

Niobium-titanium (Ni-Ti) alloys display superior high-critical-magnetic-field and high-critical-supercurrent-

density properties coupled with affordability and good workability. This combination of properties

distinguishes this material from thousands of other superconductors and explains its status as the most

commonly used superconducting material.

Nb-Ti superconducting magnets have been widely used in magnetic resonance imaging (MRI), particle

accelerators and colliders 17. Vanadium-gallium (V3Ga) is an example of a currently-available substitute for

Nb-Ti alloys with a structure of superconducting phase similar to that of Nb-Ti superconductors. High-

temperature superconductors, such as bismuth strontium calcium copper oxide (BSCCO) have great

potential as substitutes for Nb-based superconductors. In particular, BSCCO is unique among high

temperature superconductors because it can be made into round wires, a product form that is much more

flexible for making magnets. BSCCO can enable a new generation of more powerful superconducting

magnets in a few years when its production technology becomes sufficiently developed.

Summary

A number of viable substitutes can be found for niobium as an alloying element in stainless steels.

Replacement of niobium in HSLA steels seems to be more problematic especially in products intended for

use in oil & gas pipelines where substitution of niobium appears unlikely at the moment. Substitution of

niobium in super-alloys and in applications typical for Nb-containing super-alloys as well as in

superconducting magnets is a matter of time and further technical development in materials science.

Figure 2: Distribution of end-uses3 and corresponding substitutability assessment for niobium. The manner



References 1 Atomistry.com Niobium Applications. http://niobium.atomistry.com/application.html. Accessed 16 July

2013 2 Georgia State University (2007) Superconducting Magnets. http://hyperphysics.phy-

astr.gsu.edu/hbase/solids/scmag.html. Accessed 16 July 2013 3 NioCorp Developments Ltd. About Niobium. http://www.quantumrareearth.com/about-niobium.html.

Accessed 16 July 2013 4 REE International Niobium. http://www.reeinternational.com/projects/niobium/. Accessed 16 July 2013 5 Metal-Pages (2013) Metal Prices: Ferroniobium. http://www.metal-

pages.com/metalprices/ferroniobium/. Accessed 30 August 2013 6 U.S. Geological Survey (2013) Mineral commodity summaries 2013 7 United Nations Development Programme (UNDP) (2013) The 2013 Human Development Report –




European Commission 11 Papp, J. F. (2013) Niobium (columbium), in: U.S. Geological Survey (ed.) Mineral Commodity

Summaries 2013, pp. 110–111 12 ЗАО ТЕХНОИНВЕСТ АЛЬЯНС Market Niobium. http://columbite.ru/?page_id=44. Accessed 16 July

2013 13 IAMGOLD Corporation (2012) Niobium 101. http://www.iamgold.com/English/Operations/Operating-

Mines/Niobec-Niobium-Mine/Niobium-101/default.aspx 14 Patel S, Smith G (2002) The role of Niobium in wrought superalloys. WV 25705-1771 15 Hidaka S (2012) Superalloys versus Ceramics: Will Investment Casting survives as key technology of

Turbine Blades and Vanes in this century. Kyoto, Japan: The 13th World Conference on Investment Casting (WCIC)

16 Frick L (2012) Ceramic composites give super-alloys strong competition. http://machinedesign.com/news/ceramic-composites-give-super-alloys-strong-competition. Accessed 16 July 2013

17 American Magnetics (2012) Characteristics of Superconducting Magnets. http://www.americanmagnetics.com/charactr.php. Accessed 16 July 2013

11. Platinum Group Metals

The Platinum Group Metals (PGMs) consist of a group of 6 chemically very similar elements which are

further classified as the light platinum metals ruthenium (Ru) rhodium (Rh) palladium (Pd) and the heavy

platinum metals iridium (Ir), osmium (Os), and platinum (Pt). In general, PGMs exhibit high density, high

electrical conductivity, high melting points and low reactivity. Other properties typical of transition metals

are very marked such as catalytic activity due to their inclination to change valence, formation of

intermediate compounds, color, paramagnetism and a strong tendency to form complexes. Platinum is the

metal that is the commercially most important of all the PGMs, having the largest range of applications from

jewelry to autocatalysts to electronics. Because of the unique properties of PGMs, substitutes for these

elements are practically nonexistent, although they can in some situations substitute each other.1,2

PGMs are generally found together in nature, with the concentration of platinum and palladium being higher

than that of the other PGMs. Therefore, platinum and palladium also dominate the production figures for

PGMs. PGMs are extracted either as main metals (with co-production of all PGMs) or as a by-product of

nickel mining. The former is the case for deposits mined South Africa, Zimbabwe and USA while the latter

case applies to Russia and Canada. Deposits in Russia and North America have high palladium contents

while the deposits in South Africa are richer in platinum 3. By far the largest primary (mine) producers of

PGMs are South Africa and Russia, together accounting for more than 85% of world primary supply.

Figure 1: Distribution of PGM production4 and corresponding scores of the producing countries in the



determining critical raw materials.8 ZAF = South Africa; RUS = Russia.

Global production of platinum has been declining from its peak of 320 tons in 2006, and in 2012 was down

to 300 tons. The supply situation is extremely tight, with 72% of production located in South Africa. World

primary production of palladium stands at about 230 tons per year, with 44% of supplies coming from

Russia and 35% from South Africa 9. Canada, the US and Zimbabwe are minor suppliers of palladium.

Traded volumes have been higher than production during recent years, due to the sale of Russian

stockpiles, but experts consider that this source is largely depleted now.10

The high prices of PGMs have encouraged the establishment of efficient recycling chains (see Table 1) for

both pre-consumer scrap (e.g. ruthenium sputter targets in the electronic industry) and post-consumer

scrap (in particular, catalytic converters from motor vehicles; recycling from smaller applications such as

hard disk drives is not yet economical).11 The sale of residues containing platinum and palladium is in many

cases an important source of income (or cost reduction) for companies employing them in their processes

despite strong and daily price fluctuations.

Table 1: Snapshot of individual PGM prices (12 July 2013; excluding osmium) and associated recycling

rates.12,13

PGM Metal Price $/oz % of supplies from recycling

Platinum 1521 26

Palladium 740 26

Rhodium 1010 26

Iridium 800 25-50 (post-consumer scrap)

Ruthenium 70 10-25 (post-consumer scrap)

Figure 2: PGM price development during 1980 – 2011. The unit value of PGM reports the value of 1 metric

ton (t) of PGM apparent consumption (estimated).14

The main driver for the demand for platinum, palladium and rhodium is the need for emission reduction

from motorized transport and the related legislation obliging the automotive industry to equip gasoline and

diesel engines with catalytic converters. The high costs and price volatility are potential drivers for

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developing substitutes, particularly for platinum and palladium.* Any successful substitution strategy in the

field of autocatalysts would considerably ease the strain on the platinum, palladium and rhodium markets

(but would hardly affect the minor PGM metals). The expected extension of emission limits to China and

other emerging economies, and to diesel motors used for non-road purposes, is expected to lead to further

(upward) pressure on prices even if new deposits can be developed (due to the long lead times of 8-10

years).10


Autocatalysts

PGM use for catalysts in the automotive industry—mainly platinum and palladium—has been the prime

driver for demand growth in recent years.15 40% of platinum demand, 67% of palladium and 81% of

rhodium (data referring to 2012) is related to the production of different types of autocatalysts. An

autocatalyst, or catalytic converter, is a cylinder made from ceramic or metal and coated with a solution of

chemicals, including PGMs. It is installed in the exhaust line of the vehicle, and converts over 90% of

pollutants including hydrocarbons, carbon monoxide and nitrogen oxides into carbon dioxide, nitrogen and

water vapour.9 Therefore, autocatalysts reduce the environmental impact and toxicity of vehicle engine

emissions. The PGM loading in a catalytic converter depends on the engine type and emission standards.

It ranges from one to two grams for a small car in a lightly regulated environment to 12-15 g for a large

truck with stringent regulation.

PGMs in catalytic converters have proven extremely difficult to substitute, although they are eminently

suitable for recycling. Currently, the only viable substitution option is replacement of platinum with

palladium and vice versa.2 Substituting PGM content in catalytic converters in cars is the most promising

market in terms of business volume. Research into substitutes has been ongoing for many years, but as of

yet, no appropriate substitute with the same catalytic power and durability has been commercialized.

Several promising research approaches are briefly described here.

Research funded by the Renewable Fuels Association (2002-2007) examined the potential for

replacing platinum in catalytic converters with transition metal carbides and oxycarbide

nanoparticles.16 Although this research did not lead to a suitable substitute, it led to significant

advances in nanoparticle synthesis. Recent results in the field of combustion synthesis of

nanoparticles show some promise for the substitution of palladium in catalysts with nanoparticles

containing copper and chromium.17 Production costs for combustion synthesis compare very

favourably to prices for mined metals, even at laboratory scale. This is particularly so in the case of

the highly priced platinum and palladium.†

A similar strategy is pursued by the NextGenCat project (FP7), which aims to fully or partially

replace PGMs in catalytic converters using comparable transition metal nanotechnology. The

project strategy is to tightly control the incorporation of transition metal nanoparticles into the

catalyst substrate precursor using adsorption and ion-exchange. In principle, this should allow for

highly efficient catalysis that could ultimately phase out PGM use in converters.

* Iridium prices have also shown some oscillations in recent years but prices for ruthenium and osmium have been stable. † The cost of producing a potential substitute material derived from Cu metal oxides by combustion synthesis on

laboratory scale is estimated at around 10,000 to 11,000 €/ton based on Tecnalia's personnel and equipment costs; this estimate does not accounting for the saving potential of industrial-scale processes.

Research into perovskite oxides La1–xSrxCoO3 and La1–xSrxMnO3 by the GM Research and

Development Team (2010) yielded the creation of a strontium-doped catalyst that is as effective as

some current platinum designs. However, this converter still relies on palladium in order to catalyse

the oxidation of hydrocarbons and carbon monoxide, which although being a cheaper option than

platinum, still does not resolve the dependence on PGMs.

Since, attempts to substitute PGMs in catalytic converters have so far been unsuccessful, research efforts

have also focussed on the reduction of PGM content in existing converters and more commercial success

has been achieved against this target.18,19

Jewellery

Jewellery accounts for 20% of PGM use, mainly employing platinum with at least 85% purity. Other

elements that make up the remaining 15% include palladium, iridium, ruthenium, copper and cobalt.

Rhodium is mainly used in jewellery as plating for decorative and protective purposes. Platinum can be

found in most jewellery applications. Its strength and resistance to tarnish in addition to the fact that it can

be heated and cooled without hardening and oxidation effects, all the while retaining its shape, allows for

the secure setting of precious stones and its flexibility in usage for a wide range of jewellery applications.9

Trends in PGM consumption by the jewellery sector point to an increasing acceptance of palladium in

China and India, so that stronger demand is expected in this business, possibly substituting platinum use in

jewellery.9

Electronics

11% of PGMs are destined for use in the electronics and electric sector. Palladium, rhodium and platinum

are used in electrical contacts for their resistance to sparking, erosion, corrosion and because they do not

become welded together.20 Platinum and, especially, palladium are utilized in electronics because of their

electrical conductivity and durability. Palladium is used in almost every type of electronic device, from basic

consumer products to specialized hardware. Its main applications include multi layer ceramic (chip)

capacitors (MLCC); conductive tracks in hybrid integrated circuits (HIC); plating connectors and lead

frames. The electronics industry started to search for substitute materials at the end of the last century,

after a major palladium shipment crisis in 1997, and the consequences of this strategy are now apparent in

the palladium market. Particularly for MLCC (an important use of palladium in this sector), market

observers have already confirmed the impact of substitution strategies based on nickel and copper together

with a steady reduction of the palladium content of multi-layer ceramic capacitors. The improving

performance and reliability of base metal capacitors has enabled manufacturers of electronic systems to

employ them in applications where previously only the performance of precious metals was acceptable. For

example, palladium capacitors have been displaced from many automotive electronics and their use is

increasingly confined to more demanding applications such as military aircraft systems. Even though the

demand for MLCCs is still increasing (driven by smart phones, tablets and automotive electronics),

palladium consumption in this application is now decreasing.9,12 Current research aims at developing

advanced capacitors—or supercapacitors—and batteries based on graphene for use in smart phones, but

no estimates of substitution effects of PGM metals have been found so far.

A second main application of PGMs in electronic equipment are hard disks, in which data storage density is

increased substantially by applying small amounts of this metals to chip resistors and electrical contacts. In

hard disks, platinum is found in the magnetic sublayer together with cobalt and chromium and is preferred

due to its thermal stability. Ruthenium is also needed because it aids in orienting the magnetic grains and

reduces interference between layers. 9 For this application, an interesting example for substitution through

product innovation can be observed: demand for ruthenium for computer hard disks, fell by just over 9% in

2012, partially due to a technology shift towards tablets and smart phones. Platinum and rhodium are

applied in thermocouples due to their high thermal stability and in resistance thermometry because of its

exceptional electrical resistivity.20 Thermocouples for the semiconductor industry are important due to their

potential importance for energy harvesting through thermoelectric devices. For this purpose, both platinum

and rhodium, as well as other materials combinations are being researched.21. Alternatives to PGM

materials for energy-harvesting are the so-called semiconductor thermoelectric generator TEG22 with one

promising candidate material being silicon nanowires.

Potential uses of ruthenium for the energy sector are solar energy technologies, due to the metal’s ability to

absorb light throughout the visible spectrum, as well as superconducting materials. Materials combinations

including ruthenium are widely researched for the fabrication of dye-sensitized solar cells.23

Catalysts: chemicals, petroleum and other fuel production

The share of PGMs which is used by the chemical industry as catalysts is 6%. Many chemical processes

employ PGMs to improve the efficiency of various reactions.

Rhodium, palladium and platinum are utilized as homogeneous catalysts, their properties that make them

ideal for these applications are their high activity (leads to low concentration), high selectivity, and mild

reaction conditions.20 For this sub-sector, silicone production represents the major use of platinum, followed

by bulk chemical production (nitric acid for fertilizer production and paraxylene, a building block in PET

manufacture), petroleum reforming and speciality chemical production (notably pharmaceuticals). The

predominant uses of palladium in the sub-sector are PET and nitric acid production. Rhodium is utilised in

the production of acetic acid and oxo-alcohols, supplying the paint, solvent and polymer industries.

The petroleum sector is responsible for 1% use of PGMs as catalysts for cracking. Platinum, palladium,

rhodium, iridium, and ruthenium are all used as heterogeneous catalysts (and are recovered from spent

catalysts) for their efficiency of reaction. Platinum is also used in the production of high-octane gasoline for

automobiles and piston-engine aircraft.20 An important field of research employing ruthenium is its use as

catalyst for CO2 hydrogenation and related strategies for using CO2 as prime material for industry and

transport, although there is also strong research activities in alternative methods for CO2 conversion, which

do not rely on scarce materials or try to avoid the need for catalysts.

Palladium is still being used in innovative technologies, for example in membranes for separation of

hydrogen from CO2. However, due to its very high price, research naturally aims at reducing palladium

content of an application to a minimum. In the mentioned membranes, palladium sheets are reduced to 600

- 800 nanometers, so that only a very small part of the costs of a membrane is actually related to palladium

use. As is the case for other applications, substitution options for PGM-containing industrial catalysts are

extremely limited; substitution is currently either not possible or results in a significant loss of performance.

Nickel, rhodium, ruthenium are substitutes for platinum in theory, but in practice reactions are very

substrate specific. Often the only option available is substitution of one PGM for another, and even this

conservative approach often involves compromise. For many catalytic applications, despite the high

materials cost, there is little drive to substitute. Catalysts pay their way: small amounts are required relative

to total production, they are often efficiently recycled and an effective catalyst can often confer additional

efficiency gains (for example reduced water usage or lower temperatures and pressures).

On the other hand, substitutes for catalysts used in dissipative applications where there is no possibility of

recycling are highly desirable. However, finding these replacements represents an enormous technical

challenge. QID Nanotechnologies is a small European company dedicated to developing nanomaterials to

replace PGMs in catalysis. Dow Corning reported that extensive R&D efforts have failed to identify a viable

alternative to platinum catalysts for pressure sensitive release coating applications used widely as the

backing for labels and envelopes. Instead the company focussed its innovation efforts on technologies

which delivered reduced platinum content of 50-80%. Academics have also recognised the opportunity24–26.

Further applications are electrodes in fuel cells (discussed in detail in the next paragraph), and oil refining.

Platinum catalysts are also used in the growing biomass conversion sector, which includes bioethanol,

hydrogen and platform chemical production. Some substitution efforts are in progress including research

into nickel catalysts for hydrogen production from biomass and increased use of biocatalysts.

Platinum is further used as a catalyst in fuel cells mainly because of its high catalytic activity and

selectivity.9 Future demand curves for platinum for mobility will be largely determined by the composition of

the vehicle fleets, i.e. the global uptake of plug-in hybrid electric vehicles (PHEVs), battery electric vehicles

(BEVs), and fuel cell vehicles (FCVs). The 2012 International Energy Agency (IEA) case study27 predicts an

uptake of 27 million PHEVs and BEVs by 2020 in their “improve” scenario, although they acknowledge that

this is dependent on a fast rate of development for these vehicles. PHEVs continue to require an

autocatalyst (see separate section above), however BEVs and FCVs do not, although FCVs still require a

significant quantity of platinum used as catalyst. This dependence on platinum could severely compromise

the deployment of fuel cell technologies, which presently require 46 g for a 50 kWh fuel cell, costing

approximately €2000. Even accounting for technological advances to reduce Pt content in fuel cells to 5

g—already achieved on laboratory scale due to better deposition techniques—between 17,300 and 20,500

tons of platinum are expected to be employed in fuel cell vehicles between 2005 and 2050. In order to

overcome this potential bottleneck, minimization strategies are pursued through new deposition techniques,

which aim at maintaining the catalytic effect of platinum, while reducing costs substantially.

For fuel cells as well as for advanced metal-air batteries strong research efforts are ongoing to develop

metal-free electrocatalysts approaches, and include use of graphene and of biobased materials combined

with nanoparticles (see Cao et al.28,29 for a recent example).

Dental alloys

With a share of 6%, PGMs are employed in dental alloys known as “standard” alloys as well as in alloys

with ceramic veneering. Platinum, palladium and silver are used for standard alloys mainly due to their oral

stability, for the whitening of the alloy and to increase the melting range.20. However, in dental implants,

palladium has by now been successfully substituted by base metals and advanced ceramics.

Glass making equipment

Glass making equipment makes up 2% of total PGM use. Platinum and platinum alloys are used in the

fabrication of vessels that hold, channel and form the molten glass because of platinum’s high melting point

and strength. The addition of rhodium increases the strength of platinum equipment and extends their life.9

Large amounts of platinum and rhodium are used in the production of Liquid Crystal Displays (LCD). This is

mainly due to their resistance to corrosion, high melting point and strength since LCDs are produced under

extremely harsh conditions and demand high quality.9

PGM consumption by the glass industry is expected to increase in the coming years, due to growing

“demand for increasingly sophisticated electronic displays, solar panels and lightweight, durable glass fibre

composite materials”.30 No indication was found as to suitable substitutes for PGM in this use.

Summary

Table 2 shows the present uses of the six PGMs in all relevant applications. Potential uses with possibly

strong impacts on PGM demand, others than those listed in the table, are discussed above. Historically,

there have been strong substitution trends within the group of platinum metals, taking advantage of the

lower-priced palladium and rhodium to reduce platinum content. The automotive industry, for example,

introduced changes to the fuel technologies to permit the use of up to 25% of palladium in catalysts for

diesel-powered engines, which, before the year 2000, had to be made entirely of platinum31. The trend is

still visible in the jewellery business, with an increasing acceptance of palladium by clients in India and

China12, but the palladium market already shows a supply deficit, which strongly limits substitution

strategies.

In view of the difficulties of substituting PGM, minimization strategies can be observed in many industries

and research projects. However, this approach has a serious draw-back, as it can render recycling

uneconomical.

Table 2: Summary of uses of individual platinum group metals.

Material End use category

Concrete applications/examples

Platinum Autocatalysts Catalytic converters

ceramic capacitors in electronic devices; glass for fiber optics

Jewellery

Electrical and electronics

High temperature thermocouples; switch contacts in automotive controls; Semiconductor crystals for lasers; alloys for magnetic disks (computer hard drives); switch contacts in substitute for gold in electronic connections

Catalysts (chemicals & fuels)

Diverse incl. manufacture of silicones and hydrogen production

Dental alloys

Glass making equipment

Others Fuel cells (mobile, stationary), high temperature alloys for air planes; medical industry (pace-makers electrodes, aural and retinal implants, anti-cancer drugs), dental implants; high quality flutes; smoke and carbon monoxide detectors; coatings for razors; Hydrogen separation membrane

Palladium Autocatalysts Catalytic converters

Jewellery

Material End use category

Concrete applications/examples


High temperature thermocouples; electrical connection; nuclear reactors


Diverse chemical processes incl. hydrogen production

Dental alloys

Others Hydrogen separation membranes

Rhodium Autocatalysts Three-way catalytic converters for gasoline engines

Jewellery


Liquid crystal displays (LCDs); Semi-conductors for LED


Production of oxo-alcohol and nitric oxide for fertilizers and explosives; refining

Others Glass, mirrors

Iridium Jewellery


Semi-conductors for LED (mobile phones, flat panel displays and touchscreen); satellite receiver, wireless communications; military electronic systems


Production of chlorine and caustic soda

Others Alloys for aircrafts, space launch vehicles, lasers for medical and industrial welding applications; medical scanners, surgical tools and implants; glass industry, optical coatings

Ruthenium Jewellery


Hard disks; chip resistors, electrical contacts


Fuel production (hydrogen, natural gas, methanol), chlorine production

Others Solar energy; superconductors, wear resistant alloys, glass industry

Osmium Others Hard electrical contacts; Medical: surgical implants; microscopy; pen tips; needles

Figure 3: Distribution of end-uses and corresponding substitutability assessment for PGM. The manner and

scaling of the assessment is compatible with the work of the Ad-hoc Working Group on Defining Critical

Raw Materials (2010).

References 1 POLINARES Consortium (2012) Fact Sheet: Platinum Group Metals. POLINARES working paper n. 35 2 Loferski, P. J. (2013) Platinum-Group Metal, in: U.S. Geological Survey (ed.) USGS Minerals

Information - Mineral Commodity Summaries, pp. 120–121 3 Hagelüken, C. (2006) Markets for the catalyst metals platinum, palladium and rhodium. Metall 60 4 IntierraRMG (2013) Raw Materials Data - The mining database. Sweden 5 United Nations Development Programme (UNDP) (2013) The 2013 Human Development Report –




European Commission 9 Johnson Matthey Plc (2013) Platinum Today: Applications. http://www.platinum.matthey.com/about-

pgm/applications. Accessed 9 July 2013 10 BullionVault (2013) Gold News: Platinum: A 21st Century Mining Story.

http://goldnews.bullionvault.com/platinum-mining-031320132. Accessed 8 August 2013 11 IPA (2012) Recycling of PGM Secures the Supplies of Key Industry Sectors 12 Johnson Matthey Plc (2013) Platinum Today: Price charts.

http://www.platinum.matthey.com/prices/price-charts. Accessed 31 August 2013 13 United Nations Environment Programme (UNEP) (2012) Metal stocks and recycling rates.

http://www.unep.org/resourcepanel/Portals/24102/PDFs/Metals_Recycling_Rates_Summary.pdf 14 Kelly, T., H.E. Hilliard, H., George, M., Loferski, P. (2012) Platinum Group Metals (PGM): Supply-

Demand Statistics, in: U.S. Geological Survey Minerals Information 15 Yang, C. (2009) An impending platinum crisis and its implications for the future of the automobile.

Energy Policy 37(2009), 1805–1808 16 Rumaiz, A., Lin, H., Baldytchev, I., Shah, S. (2007) Nanosized tungsten carbide for NOx reduction.

Journal of Vacuum Science and Technology B. Microelectronics and Nanometer Structures 25(3), 893–898

17 Xanthopoulou, G. (2010) Catalytic Properties of the SHS products. Review. Advances in Science and Technology(63), 287–296

18 Johnson, T. V. (2013) SAE 2012 World Congress: Vehicular emissions control highlights of the annual Society of Automotive Engineers (SAE) international congress. Platinum Metals Rev 57(2), 117–122

19 Kuchenbrod F (2013) Novel Gas Catalysts – Ceramic Foam Cleans Up Exhaust Gases. http://www.empa.ch/plugin/template/empa/3/135339/---/l=2/changeLang=true/lartid=135339/orga=/type=/theme=/bestellbar=/new_abt=/uacc=. Accessed 9 August 2013

20 Renner, H., Schlamp, G., Drost, I., Lüschow, H. M., Tews, P., Panster, P., Diehl, M., Lang, J., Kreuzer, T. K. A., Starz, K. A., Dermann, K., Rothaut, J., Drieselmann, R., Peter, C., Schiele, R. (2001) Platinum Group Metalsand Compounds, in: Ullmann's Encyclopedia of Industrial Chemistry, pp. 317–388. Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA

21 Johnson Matthey Plc (2012) Platinum Today: New Application Developments in PGMs. February 2012. http://www.platinum.matthey.com/media/1373147/new_application_developments_pgms_february_2012.pdf. Accessed 8 August 2013

22 Maharaj S, Govender P. (2013) Waste Energy Harvesting with a Thermoelectric Generator. http://active.cput.ac.za/energy/past_papers/DUE/2013/PDF/Papers/13%20-%20Maharaj,%20S.pdf

23 Bomben, P., Robson, K., Koivisto, B., Berlinguette, C. (2012) Cyclometalated ruthenium chromophores for the dye-sensitized solar cell. Review Article, in: 19th International Symposium on the Photophysics and Photochemistry of Coordination Compounds, pp. 1437–1786

24 Bullock RM (ed.) (2010) Catalysis without precious metals. Weinheim: Wiley-VCH

25 Bullock RM (2011) Homogeneous Catalysis Without Precious Metals: “Cheap Metals for Noble Tasks”: Workshop on “The Role of Chemical Science in Finding Alternatives to Critical Resources". http://dels.nas.edu/resources/static-assets/bcst/miscellaneous/Bullock_NAS.pdf. Accessed 30 August 2013

26 Tondreau, A. M., Atienza, C. C. H., Weller, K. J., Nye, S. A., Lewis, K. M., Delis, J. G. P., Chirik, P. J. (2012) Iron Catalysts for Selective Anti-Markovnikov Alkene Hydrosilylation Using Tertiary Silanes. Science 335(6068), 567–570. 10.1126/science.1214451

27 IEA (2013) EV City Casebook - A look at the global electric vehicle movement. http://www.iea.org/evi/evcitycasebook.pdf

28 Cao, R., Thapa, R., Kim, H., Xu, X., Gyu Kim, M., Li, Q., Park, N., Liu, M., Cho, J. (2013) Promotion of oxygen reduction by a bio-inspired tethered iron phthalocyanine carbon nanotube-based catalyst. Nat Comms 4. 10.1038/ncomms3076

29 Ulsan National Institute of Science and Technology (UNIST) (2013) New Catalyst replaceable platinum for electric-automobiles: Affordable and scalable process of a carbon nanotube-based catalyst outperforming platinum for electric-automobiles

30 Johnson Matthey Plc (2011) Special Feature: PGMs in glass manufacturing. http://www.platinum.matthey.com/media/820177/pgms_in_glass_manufacturing.pdf. Accessed 9 August 2013

31 Mineweb.com Platinum Group Metals: How far can palladium substitute for platinum. http://www.mineweb.com/mineweb/content/en/mineweb-platinum-group-metals?oid=46789&sn=Detail. Accessed 8 August 2013

12. Rare Earth Elements

The rare earth elements (REEs) are a group of 17 chemical elements comprising the lanthanoids* plus

scandium and yttrium. This group of elements has become almost synonymous with critical raw materials

on account of its high concentration of supply and tremendous variety of uses, coupled to a suggestive

name arising from the scarcity of the ores originally used to obtain rare earth elements from.

Though the rare earth elements are not rare in the earth’s crust - cerium, the most abundant of the rare

earths, is more abundant than copper and lead - they are difficult to recover in a pure form because of their

chemical similarity. Moreover, this chemical similarity also means that rare earth deposits contain a mixture

of rare earth elements that have to be mined and processed together as co-products. Sometimes, the rare

earth ores themselves are a by-product, as in the case of the Bayan-Obo mine—the largest single source

of rare earths.1 Needless to say, the composition of the ores available for mining does not necessarily

match current market needs.

The rare earth elements are prominently associated with green energy technologies such as wind power

(magnets) and electric vehicles (batteries).2–4 However, they are also renowned for having extremely low

recycling rates and with environmental pollution; the latter on account of the extensive processing required

to obtain them in the required purity and the association of (some of) the ores with radioactive uranium and

thorium.5

Currently, the primary production of rare earths is clearly dominated by Chinese producers, though this may

change to an extent through the (re-)opening of mines outside of China (e.g. in the USA and Australia) and

the intention of some mining companies of reclaiming REE from their tailings. Chinese export restrictions

on rare earths—which lead to a price peak of rare earth metals and their oxides in 2011 (see Figure 2)—

are currently being contested in a World Trade Organisation (WTO) dispute filed by the USA6, EU7 and

Japan7.

* Lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. These are commonly divided into “light” (lanthanum through europium) and “heavy” rare earths, though sometimes an intermediate term (“middle”) is introduced to denote the elements between europium and dysprosium.

1

Figure 1: Distribution of rare earth production 8 and corresponding scores of the producing countries in the




Figure 2: Rare earth oxides (REO) price development during 1980 – 2011. The unit value is the value in

dollars of 1 metric ton (t) of REO apparent consumption (estimated).13 Prices have gone back substantially

since their peak in 2011.

0

10

20

30

40

50

60

1980 1985 1990 1995 2000 2005 2010

Un

it v

alu

e (

1000 U

SD

/t)

Year


Magnets

Permanent magnets have fascinated people for millennia and account for close to 30% of rare earth

consumption. Today they play a key role in many emerging applications, most importantly in the production

of energy devices such as generators (wind turbines) and motors (cars), in addition to the established

markets in magnetic resonance imaging (MRIs) technology, hard disc drives, speakers etc.

In terms of value, two-thirds of the permanent magnet market is dominated by those containing rare earths.

Neodymium-iron-boron (NdFeB) magnets have energy products† close to the theoretical maximum.15,16 The

outstanding magnetic properties of rare earth based permanent magnets are due to the combination of the

high magnetic moments of the transition metals (iron, cobalt) and the exchange coupling between these

magnetic moments with those of the rare earths. This coupling results in a high magnetocrystalline

anisotropy and thus the potential to achieve a coercivity that is comparable to the magnetisation. No

material with superior qualities to NdFeB has been discovered yet. Only an incremental improvement in the

record energy product of permanent magnets has been seen during the last 20 years. It is worth noting that

neodymium-iron-boron magnets also contain small amounts of dysprosium and terbium, which are added in

order to improve confer the ability to remain magnetized when confronted with other magnetic fields or high

temperatures (at the cost of a reduced magnetisation).

There is considerable economic potential for the substitution of rare earths permanent magnets, as can be

highlighted by the example of off-shore wind farms: Many major suppliers of wind turbines have opted for

employing permanent magnet synchronous machines (PMSM) due to advantages in terms of dimension,

weight and maintenance. This type of windmill contains an average of 400 to 600 kg of rare earths in up to

two tons of permanent magnets (365 kg/MW), implying that price fluctuations of Nd and Dy have significant

impacts on production costs and profit margins. For example, the Chinese manufacturer, Goldwind,

reported that the price hikes in 2011 lowered its gross profit margin from 20% to 7%. Goldwind has since

then opted for fabricating a family of windmills without permanent magnet (rare earth) technology for lower-

cost markets and other manufacturers are developing novel wind generators with new designs, for example

superconducting materials.

In 2010, the production of permanent magnets consumed 26000 t of rare earth elements

(neodymium/praseodymium, dysprosium and terbium) while for 2015 the estimated demand is 48000 t.17

This expected increase in demand explains the need to develop substitute materials, which can be used in

some target applications, albeit not necessarily in those which require the strongest magnet material

possible. In fact, the market potential for magnetic materials with properties between rare earth based

permanent magnets and the much weaker ferrites is considered extremely positive.16

One main approach is the minimization (as opposed to substitution) of rare earth use in permanent

magnets. There are promising ways to radically reduce the amount of the costly heavy REEs in NdFeB

magnets by optimizing the magnets microstructure, for example by exploiting grain boundary diffusion

processes.18,19

The other main approach focuses on the identification of completely new kinds of rare-earth-free magnetic

materials. One such strategy under research in order to produce hexaferrite powders is mechano-activated

† The energy product is a measure of the magnetic energy stored in a permanent magnet. A small magnet with a large

energy product and a large magnet with a small energy product may serve the same use 14

.

self-propagating high-temperature synthesis.20 Fabricating soft and hard magnets by combustion synthesis

is an easy-to-handle process, which uses inexpensive oxides and achieves acceptable magnetic

properties, which can be further improved by spark plasma sintering. These techniques can then be further

improved by combining combustion synthesis and spark plasma sintering (SPS) as method of fabrication of

dense β-SiAlON, iron nitride and iron-based composites. This process is highly versatile and scalable with

respect to chemistry, size and morphology. It is furthermore possible to influence the characteristics of the

magnetic field during the combustion process by aligning the particles. Fibre orientation and alignment are

considered two essential features of novel materials to be derived from hexaferrite fibres. Nanocomposite

materials, which could potentially be the basis for new substitute magnetic materials, include mixtures of

hard magnetic barium ferrite and soft magnetic nickel zinc ferrite (Patent Number KR20080055485 (A),

Korea 2008-06-19). Further progress in this research field is expected to derive from advanced analytical

tools, which improve the researchers’ understanding of the processes taking place on the nano-scale.

Other materials under research to produce substitute magnetic materials are cerium (Ames Laboratory,

US), manganese (Pacific Northwest National Laboratory), as well as cobalt-based and samarium-based

compounds as substitute for dysprosium (Chiba Institute of Technology, Japan). From this list of potential

substitutes, notice that cerium and samarium are themselves rare earth elements and that cobalt is also

considered a critical raw material.

Metallugy: Al and Mg alloys21

REEs, primarily scandium, are used in aluminium alloys to control grain size. Scandium forms an Al3Sc

phase which has a threefold influence on the alloy: The Al3Sc phase particles can serve as a grain refiner in

the Al melt, a dispersoid for controlling the grain structure of the alloy and a strengthening precipitate.

Although there has been a great amount of research conducted on the topic, these alloys have not been

commercialized in large scale applications. Compounds that can control the grain size like titanium boride

are widely available.

Rare earths are also used in some commercial magnesium alloys—these alloys have the letter "E" in their

designation. Up to 3% of cerium and neodymium is added to sand cast magnesium to provide a low melting

eutectic phase which increases the castability. In other alloys, REE are used to improve age hardening.

These alloys with high REE are only used for advanced applications like aerospace and high-end

automotive. The REE containing alloys can be substituted with other Mg-alloys at the cost of some

performance.22

Polishing

Nano/micron-sized cerium-oxide powder is a hard material which can be used for polishing. It has a

hardness between that of garnet (silicates) and Green Rouge (chromium oxide).

Cerium-oxide has been used in polishing since the 1930s, and until the late 1990s, growth was driven by

demand from the production of CRT display faceplates. Demand has grown since the 1990s with the rapid

growth of electronic products containing glass or glass-like components, many of which require polishing to

a high standard. In 2010, demand for rare earths in polishing applications was estimated to be around

15,750 t, of which, around 75% were consumed in traditional glass applications (including display panels,

flat glass and optical glass) and around 25% in electrical components. Following high prices since 2010,

there has been a trend towards reducing the amount of cerium-oxide in polishing slurries accompanied by

shorter polishing times, smaller amounts of slurry and slurry re-use where possible. Different types of

medium hard alumina can also be used for the same purpose.23

Pigments24

Because of their unique electronic configuration, the REEs show unusual magnetic and optical properties.

Many trivalent lanthanide ions are strikingly coloured, both in solid state and in aqueous solutions. The

colour developed depends on the number of unpaired electrons. The pigments derived from rare earths

show their characteristic intense colour due to charge transfer interactions between a donor and an

acceptor, with the metal ion generally playing the role of an acceptor. Selection of REEs and appropriate

donor atoms for achieving the best spectral bandwidth and intensity forms the leading edge of knowledge in

this area. Dopants based on rare earths in mixed oxide systems offer an opportunity to tune in colour

response through manipulation of energy gaps and delocalization phenomena in conduction and valence

bands. However, the cost of separation of the rare earth metal ions makes these pigments economically

unattractive, restricting them to niche applications, limiting the economic incentive for substitution.

Metallugy: Iron and Steel25,26

Rare Earth Elements are used as alloying elements in cast-iron and steels.

In cast iron, cerium and lanthanum are used to tranform the morphology of graphite from flake to nodule

(nodularisers). Since REEs are strong sulfide formers, they form stable compounds in the melt. These

compounds nucleate graphite nodules which give the cast iron good mechanical properties. The use of

REEs in foundry alloys has been well established but alternative nodularisers based on magnesium (also a

critical raw material) are available.

Cerium is required in some special stainless steel grades. Cerium combined with silicon improves the

oxidation resistance, erosion corrosion resistance and oxide spallation resistance.

Glass

Traditionally, cerium oxide additives used in the production of CRT faceplates made up the majority of

demand in this sector. As CRTs have given way to FPDs, consumption for this application has been in

decline because the glass in FPDs is thinner. Cerium oxide is also used to prevent solarisation in

sunglasses, bottles (to protect the contents) and in the growing market of luxury vehicles (small market).23

Lanthanum has been used to increase the refractive index of glass (for use in lenses) for over 30 years.

This use has seen strong growth through security cameras, digital cameras and mobile phones with small

fisheye lenses, many of which are 50% La2O3.23

Catalysts

The dominant usage of rare earths for catalysts is lanthanum, cerium, praseodymium and neodymium for

fluid catalytic cracking in the petroleum industry. During the cracking process, the catalyst becomes

contaminated with carbon. Although the contaminated catalyst is regenerated and reused, ultimately spent

rare earth oxide catalysts become unusable and are disposed of as a waste product.27 Rising rare earth

prices have prompted companies to market services to optimise the amount of rare earth content in

catalysts for a particular process28 or develop rare earth-free alternatives.

The automotive industry generates the other major use for rare earth elements as catalysts, where rare

earth oxides (cerium, lanthanum, praseodymium and neodymium) are part of the catalytic converters.

Recycling processes for catalytic converters focus on recovering the valuable platinum and palladium and

the rare earths are generally not recovered. Since cerium is the primary rare earth element used in catalytic

converters (90% by weight29) and cerium is the most abundant of the rare earth elements, there is little

incentive to research substitutes in this particular application.

Batteries30,31

Nickel Metal Hydride (NiMH) batteries contain a mixture of REEs that are incorporated into the negative

electrode. The role of the electrode is to reversibly form a mixture of metal hydride compounds. The "metal"

M in the negative electrode of a NiMH cell is actually an intermetallic compound. The most common is AB5,

where A is a rare earth mixture of lanthanum, cerium, neodymium, praseodymium and B is nickel, cobalt,

manganese, and/or aluminium. Very few cells use higher-capacity negative electrode materials based on

AB2 compounds - where A is titanium and/or vanadium and B is zirconium or nickel, modified with

chromium, cobalt, iron, and/or manganese - due to the reduced life performances. Research is currently

being conducted into developing alternative Mg-Ni-Ti-Al-based electrode materials. Though rare earths are

not satisfactorily substitutable in this type of battery, NiMH batteries face strong competition from lithium ion

batteries.

Phosphors

Lanthanum, cerium, europium, yttrium, erbium, terbium are rare earth oxides (REOs) used for lighting

phosphors and are vital component in energy efficient fluorescent lamps.32‡ Lighting accounts for

approximately 20% of electricity use in European buildings, second only to space heating. Modern

technologies provide opportunities to significantly reduce energy demand from lighting: Fluorescent lighting,

light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs) and halogen incandescent require much

less energy than the traditional incandescent bulbs, now limited or prohibited in many European countries.

This transition away from incandescent bulbs has strengthened demand for phosphors and prompted

companies like Osram and Philips to search both for improvements and alternatives, in particular the

reduction of the required amounts.33

At this moment, there are no clear substitutes for the use in compact fluorescent light (CFL) bulbs. Costs

for LED bulbs are much higher than those of CFL bulbs, and LEDs also depend on rare earth based

phosphors. Organic LEDs (OLEDs) are a plausible rare earth free alternative, but their lifetime is too short

in relation to their costs—a problem that is not expected to be solved in the near future. Finally, rare earth

free phosphors for LEDs currently under development include silicon-based nanoparticles (1-5 nm), BCNO

phosphors§ and GaZnON (gallium is also a CRM) are potential substitutes.34–38 However, there are still

issues to be solved concerning costs, colour and thermal stability.

Ceramics

Rare earths are used in two major types of advanced ceramic applications: structural/wear-resistant

ceramics (including yttrium-stabilised zirconia, the largest use for yttrium after phosphors) and electronic

components (including dielectric ceramics). Ceramics are a small but high value market for rare earths.23

REE cannot be substituted in most of these materials.

Summary

A summary of the uses of different rare earths in the fields of use described above is given in Table 1. At

the moment, substitution of REE in phosphors, glass, catalysts and ceramics is not possible. Substitution in

magnets, batteries, polishing, pigments and as alloying elements in iron and steel can only be done through

‡ Fluorescent lamps contain halo and triphosphors. Triphosphors use rare earth oxides in their phosphor mix.

32

§ BCNO = boron, carbon, nitrogen, oxygen.

the loss of performance. The use of REE as alloying elements in Al and Mg can be avoided through

substitution of these alloys with other structural materials at the cost of a minor decrease of performance.

Table 1: Summary of end uses of rare earth elements (both as metals and oxides). The uses with the

largest share(s) for each element are marked in bold. 23,39,40 When examined as a group, the end uses of

rare earths tend to be dominated by the end uses of the four most abundant elements (lanthanum, cerium,

praseodymium and neodymium; all four are “light” rare earth elements).

Rare earth element End use

Lanthanum (more abundant)

Batteries, metallurgy, catalysts (catalytic converters, petroleum refining), polishing powders, glass additives, phosphors, ceramics, hybrid engines

Cerium (more abundant)

Batteries, metallurgy, catalysts (catalytic converters, petroleum refining), polishing powders, glass additives, phosphors, ceramics, hybrid engines

Praseodymium (more abundant)

Magnets, batteries, metallurgy, catalysts (catalytic converters), polishing powders, glass additives, ceramics

Neodymium (more abundant)

Magnets, batteries, metallurgy, catalysts (catalytic converters), glass additives, ceramics

Gadolinium Magnets, diagnostics, phosphors

Europium Phosphors, red color for TV and computer screens, medical X-ray units

Samarium Batteries, magnets

Scandium Aerospace components

Terbium Phosphors, permanent magnets

Dysprosium Magnets, hybrid engines, ceramic capacitors

Erbium Phosphors

Holmium Glass coloring, lasers

Thulium Medical X-ray units

Lutetium Catalysts in petroleum refining

Ytterbium Lasers, steel alloys

Yttrium Red color, phosphors, ceramics, metal alloys, glass additives

Figure 3: Distribution of end-uses and corresponding substitutability assessment for the rare earth elements

(taken as a group). The manner and scaling of the assessment is compatible with the work of the Ad-hoc

Working Group on Defining Critical Raw Materials (2010).

References 1 Walters, A., Lusty, P. (2011) Rare Earth Elements Profile, in: British Geological Survey (ed.)

Commodity Profiles 2 Hoenderdaal, S., Tercero Espinoza, L., Marscheider-Weidemann, F., Graus, W. (2013) Can a

dysprosium shortage threaten green energy technologies? Energy 49, 344–355. 10.1016/j.energy.2012.10.043

3 Kara H, Chapman A, Crichton T, Willis P, Morley N, Deegan K Lathanide resources, alternatives: Oakdene Hollins, 1–66

4 Moss R, Tzimas E, Kara H, Willis P, Kooroshy J (2011) Critical Metals in Strategic Energy Technologies: Assessing Rare Metals as Supply-Chain Bottlenecks in Low-Carbon Energy Technologies

5 Study on rare earths and their recycling (2011) Schüler, D., Buchert, M., Liu, R., Dittrich, S., and Merz, C. Darmstadt: Öko-Institut e.V., The Greens/ European Free Alliance

6 World Trade Organization China — Measures Related to the Exportation of Rare Earths, Tungsten and Molybdenum: Dispute DS431. http://www.wto.org/english/tratop_e/dispu_e/cases_e/ds431_e.htm

7 World Trade Organization China — Measures Related to the Exportation of Rare Earths, Tungsten and Molybdenum: Dispute DS432. http://www.wto.org/english/tratop_e/dispu_e/cases_e/ds432_e.htm

8 U.S. Geological Survey (2013) Mineral commodity summaries 2013 9 United Nations Development Programme (UNDP) (2013) The 2013 Human Development Report –




European Commission 13 DiFrancesco, C., Hedrick, J., Cordier, D., Gambogi, J. (2012) Rare Earths Elements (REE): Supply-

Demand Statistics, in: U.S. Geological Survey Minerals Information 14 supermagnete What does maximum energy product mean?

http://www.supermagnete.de/eng/faq/What-does-maximum-energy-product-mean. Accessed 1 August 2013

15 Gutfleisch, O., Willard, M. A., Brück, E., Chen, C. H., Sankar, S. G., Liu, J. P. (2011) Magnetic Materials and Devices for the 21st Century: Stronger, Lighter, and More Energy Efficient. Adv. Mater. 23(7), 821–842. 10.1002/adma.201002180

16 Coey, J. (2012) Permanent magnents: Plugging the gap. Scripta Materialia 67(6), 524–529. 10.1016/j.scriptamat.2012.04.036

17 Gündoğdu, T., Kömürgöz, G. (2012) Technological and economical analysis of salient pole and permanent magnet synchronous machines designed for wind turbines. Journal of Magnetism and Magnetic Materials 324(17), 2679–2686. 10.1016/j.jmmm.2012.03.057

18 Park, K., Hiraga, K., Sagawa, M. (2000) Proc. 16th Int. Workshop on RE Magnets and their Applications. The Japan Institute of Metals, Sendai, Japan, 257–264

19 Komuro, M., Satsu, Y., Suzuki, H. (2010) Increase of Coercivity and Composition Distribution in Fluoride-Diffused NdFeB Sintered Magnets Treated by Fluoride Solutions. IEEE Trans. Magn. 46(11), 3831–3833. 10.1109/TMAG.2010.2064780

20 Naiden, E., Zhuravlev, V., Suslyaev, V., Minin, R., Itin, V., Korovin, E. (2011) Magnetic Proporties and Microstructure of SHS-Produced Co-Containing Hexaferrites of the Me2W System. International Journal of Self-Propagating High-Temperature Synthesis 20(3), 200–207

21 Røyset, J., Ryum, N. (2005) Scandium in aluminium alloys. Int. Mat. Rev. 50(1), 19–44. 10.1179/174328005X14311

22 Avedesian M, Baker H (eds.) (1999) ASM Specialty Handbook: Magnesium and Magnesium Alloys: ASM International

23 Roskill Information Services (2011) Rare Earths & Yttrium: Market Outlook to 2015

24 Sreeram, K. J., Kumeresan, S., Radhika, S., Sundar, V. J., Muralidharan, C., Nair, B. U., Ramasami, T. (2008) Use of mixed rare earth oxides as environmentally benign pigments. Dyes and Pigments 76(1), 243–248. 10.1016/j.dyepig.2006.08.036

25 Skaland, T. (2003) Ductile iron shrinkage control through graphite nucleation and growth. International Journal of Cast Metals Research 16(1-3), 11–16

26 van der Eijk, C., Grong, Ø., Haakonsen, F., Kolbeinsen, L., Tranell, G. (2009) Progress in the development and use of grain refiner based on cerium sulfide or titanium compound for carbon steel. ISIJ International 49(7), 1046–1050

27 Goonan, G. Rare Earth Elements-End Use and Recyclability, in: U.S. Geological Survey Hg 2011- Minerals Year Book

28 BASF (2011) Technical Note 29 INSEAD (2011) Faculty & Research Working Paper 30 Liu, Y., Cao, Y., Huang, L., Gao, M., Pan, H. (2011) Rare earth–Mg–Ni-based hydrogen storage alloys

as negative electrode materials for Ni/MH batteries. Journal of Alloys and Compounds 509(3), 675–686. 10.1016/j.jallcom.2010.08.157

31 Rongeat, C., Grosjean, M.-H., Ruggeri, S., Dehmas, M., Bourlot, S., Marcotte, S., Roué, L. (2006) Evaluation of different approaches for improving the cycle life of MgNi-based electrodes for Ni-MH batteries. Journal of Power Sources 158(1), 747–753. 10.1016/j.jpowsour.2005.09.006

32 Osram Sylvania (2011) Rare Earth Phosphor Crisis 33 Philips (2011) Phosphor—a critical component in fluorescent lamps: Navigating through market

fluctuations 34 Credit Suisse (2011) Baotou Rare Earth 35 LumiSands Silicon nano-materials research & development for lighting. www.lumisands.com.

Accessed 9 sep 13 36 Wang, W.-N., Ogi, T., Kaihatsu, Y., Iskandar, F., Okuyama, K. (2011) Novel rare-earth-free tunable-

color-emitting BCNO phosphors. Journal of Materials Chemistry 21, 5183–5189 37 Ogi, T., Kaihatsu, Y., Iskandar, F., Wang, W.-N., Okuyama, K. (2008) Facile Synthesis of New Full-

Color-Emitting BCNO Phosphors with High Quantum Efficiency. Advanced Materials 20, 3235–3238 38 Vanithakamari, S. C., Nanda, K. K. (2009) A one-step method for the growth of Ga2O3-nanorod-based

white-light-emitting phosphors. Advanced Materials 21, 3581–3584. 10.1002/adma.200900072 39 U.S. Department of Energy (2010) Critical Materials Strategy 40 U.S. Department of Energy (2011) Critical Materials Strategy

13. Tantalum

Tantalum is a dense, ductile and malleable metal of grey-blue colour. It has good thermal and electrical

conducting properties. It is easy to machine, and its fusion temperature is one of the highest amongst

metals, after that of tungsten, rhenium and osmium. It is also biocompatible which makes it useful for

medical applications. Tantalum also has near-zero electric resistance at low temperature, high corrosion

resistance, shape memory properties and high capacitance.1

Tantalum is mostly used (60%) in the production of capacitors used in electronics (smartphones,

computers, wireless equipment, etc.).2 It is also used as an alloying element for super-alloys in turbines,

aircraft engines and defence applications. Its resistance to corrosion and high-temperature enable its use in

demanding industrial environments, cutting tools and as a refractory material.3

Tantalum is a high value metal that is recovered both as a main metal and as a by-product of tin

operations, the latter source accounting for up to one fifth of total tantalum supply. Because of its high

value, tantalum (like tin, gold and tungsten) lends itself to small scale and artisanal mining (ASM), and has

been prominently linked to the conflict in the Democratic Republic of Congo. ASM can contribute

significantly - an estimated one fourth of global mining production in 2009, similar to gold and tin—to the

global supply of tantalum 4,5. Because of this large contribution, it is difficult to obtain reliable statistics for

tantalum mining in Africa. Traditionally, Australia has been a major producer of tantalum; however, mining

operations have been intermittent in recent years because of low prices. Brazil has recently strengthened

its position as leading tantalum supplier, followed by Mozambique and Rwanda.

Tantalum can be recycled from metallic scrap, however its major use in electronics is of a dissipative

nature. Tantalum process scrap coming from the manufacturing of capacitors are claimed to be fully

recycled.6 Aside from this recycling in capacitor manufacturing, tantalum recycling comes from other

applications such as cemented carbide and alloys (old scrap), spent sputtering targets and edge trimming

and shavings from metallurgical processes (new scrap). About 300-400 t of secondary tantalum are

currently used. This may represent ~20% of total supply provided through recycling1 (figures varies

between 10% and 30% recycling, depending on the source).

Figure 1: Distribution of tantalum production7 and corresponding scores of the producing countries in the



determining critical raw materials 11. BRA = Brazil; MOZ = Mozambique; RWA = Ruanda; AUS = Australia;

CAN = Canada.

The price of Tantalite (Ta2O5) increased significantly (284%) in the period from 2009 to 2011.The annual

price reported in Ryan’s Notes is 56.82 US$/kg in 2011.12 In 2013 the price of Tantalite decreased

continuously.13

Figure 2: Tantalum price development during 1980 – 2011. The unit value is defined as the value of 1

metric ton (t) of tantalum apparent consumption (estimated).14

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Tantalum is mostly used in capacitors, cemented carbides and super-alloys for aerospace, automobile,

defence and turbine applications.

Capacitors

The major use of tantalum powder is in ceramic capacitors, thanks to its high capacitance coefficient that

enables smaller components for miniaturized and portable electronics. These components are also robust,

temperature tolerant, and with low default rate. Although the material quantity per capacitor is small,

electronic devices may contain numerous capacitors; a recent smartphone contains approximately 23

capacitors and smartphones are produced in very high numbers. The multiplicity of the electronic

applications (automotive electronics, portable electronic boards, smartphones, etc.) and their mass

production represent a massive ~50-60% of tantalum use.1

Different tantalum powders are used to manufacture capacitors for high-voltage applications, low-voltage

and high-capacitance applications, or medium-voltage and medium capacitance applications.15

In terms of substitution, niobium (also considered a critical raw material) can be used to produce capacitors

at lower cost, but they are usually larger and have a shorter life-span.16 Standard aluminium capacitors are

possible alternatives, but are more sensitive to harsh and hot operating conditions. Ceramic capacitors are

also an option. The superior performance and robustness of tantalum capacitors remains, however, the

best choice in applications where size and/or security matters (e.g. automobile anti-lock brake systems,

airbag activation systems, etc.).

Cemented carbides1

Tantalum carbide is an extremely hard refractory ceramic which can be used for the production of high-

speed cutting and boring tools, or other environments with high levels of stress and temperatures. Teeth for

excavator buckets, mining drills and high-performance bearings are possible applications. These carbides

are also used in refractory parts and coatings for furnaces and nuclear reactors.

In carbides applications, possible substitution of tantalum by niobium (CRM) is possible, as well as the use

of tungsten (CRM) and titanium carbides (TiC) and nitride (TiN) are also possible.

Aerospace & automobile super-alloys

Tantalum super-alloys are used mostly in aerospace (75% of super-alloy demand, including jet engine and

rocket engine nozzles) and defence applications (e.g. missile parts). These are typically Ni-based super-

alloys with a tantalum fraction, but can also be tantalum-based super-alloys. These super-alloys are also

used in other turbine-type equipment (e.g. gas turbines). Tantalum-ruthenium alloy is used in the military for

its oxidation resistance and shape memory properties.

In steel super-alloy applications where strength is required at high temperature, tantalum addition can be

replaced by vanadium or by molybdenum. Other possible substitutes for high-temperature applications can

be hafnium, iridium (CRM), molybdenum, niobium (CRM), rhenium and tungsten (CRM).12

Process equipment

Tantalum alloys are usually used in applications which require corrosion resistance, good high-temperature

and thermal/electric conductivity behaviour such as chemical processing equipment including heat

exchangers, boilers, condensers, pressure reactors, distillation columns, crucibles, etc. Tantalum is also

used to produce dimensionally stable anodes that can be used in extreme environments such as in the

production of chlorine and soda in systems with ion exchange membranes.1

In the domain of industrial resistance to corrosion and high-temperature environment, niobium (CRM) can

be substituted for tantalum due to similar crystallographic properties. Other possible corrosion-resistant

substitutes can be glass, platinum (CRM), titanium and zirconium. As for super-alloys, possible substitutes

for high-temperature applications can be hafnium, iridium (CRM), molybdenum, niobium (CRM), rhenium

and tungsten (CRM).12

Surgical applications & others

Tantalum alloys are used in invasive medical applications such as surgical tools, pacemakers (coating and

capacitors) and prosthesis devices either as metal or coating (e.g. hip joints, skull plates, stents for blood

vessels) owing to the biocompatibility of tantalum. It is also used in hearing aids. Some orthopaedic

applications of tantalum in prosthetics can be substituted by titanium and ceramics, but some specific

applications cannot be substituted, for example porous tantalum alloys used in prosthetic body parts, or

pacemaker coating. Chromium/nickel steel alloys can be used for surgical equipment (e.g. stents and

pinches), but with lower durability of the oxide coating layer and a lower malleability.

Tantalum is used in optics for the manufacture of specialty glass and camera/eyeglass lens, conferring a

high-refractive index. It is also used in glass-coatings and X-ray film/absorbers. Niobium can also be used

in some cases.

Hard disk drives use tantalum or niobium (substitute but also CRM) both in the disk themselves and in the

read-write head.17

Lithium tantalite and niobate have unique optical, piezo and pyro-electric properties and are thus used in

electronic applications like surface acoustic wave (SAW) filters for sensors in cellphones, TV sets, video

recording, etc. The progressive introduction of alternative materials (e.g. La2Ga5SiO14, note that La and Ga

are both CRM) as substitutes for lithium tantalite for SAW is however observed.

The following applications of tantalum have also been identified, however, no additional information about

possible substitution has been found in literature:

In construction, tantalum is used in cathode protection systems for large steel structures (e.g. oil

platform, bridges, water-tanks), and corrosion-resistant fasteners (e.g. nuts, bolts).

Tantalum nitrite is used in LED applications, solar cells, transistors and integrated circuitry due to its

semi-conductor characteristics.

Tantalum film coating deposited by physical vapor deposition (PVD) is used in electronics to prevent

copper migration in Si and SiO2. Deposition is also used for media storage (USB key), inkjet printer

heads and panel displays. Molecular beam epitaxy equipment, which enables even thinner layers

than PVD, may also use tantalum.

Summary

The core use of tantalum in capacitors has several possible substitutes (aluminium, ceramic capacitors)

that are likely to answer most common needs. Only niche capacitor applications with strong size and

robustness/tolerance requirements may be more difficult to replace, but with lower demand volumes and

possibly higher-value.

Figure 3: Distribution of end-uses and corresponding substitutability assessment for tantalum. The manner



References 1 Audion A, Piantone P (2012) Panorama 2011 du marché du tantale: Rapport public. BRGM/RP-61343-

FR 2 Papp, J. F. (2011) Niobium (Columbium) and Tantalum, in: U.S. Geological Survey (ed.) Minerals

Yearbook 3 BRGM (2012) Le tantale. http://www.mineralinfo.fr/panoramas/TaDCE.pdf. Accessed 23 August 2013 4 Dorner, U., Franken, G., Liedtke, M., Sievers, H. (2012) Artisanal and small-scale mining (ASM).

POLINARES working paper n. 19, in: POLINARES (ed.) Identification of potential sources of competition, tension and conflict and potential technological solutions. Deliverable D02.1 of POLINARES (EU Policy on Natural Resources-Competition and collaboration access to oil, gas and minerals). Project co-funded by European Commission 7th RTD Programme

5 Buckingham, D., Cunningham, L., Shedd, K., Jaskula, B. (2012) Beryllium: Supply-Demand Statistics, in: U.S. Geological Survey Minerals Information

6 Tantalum-Niobium International Study Center (2010) Comments to the Report Critical Raw Materials for the EU. http://ec.europa.eu/enterprise/policies/raw-materials/files/pc-contributions/org-050-tantalum-niobium-international-study-center-tic_en.pdf

7 IntierraRMG (2013) Raw Materials Data - The mining database. Sweden 8 United Nations Development Programme (UNDP) (2013) The 2013 Human Development Report –




European Commission 12 Papp, F. J. (2013) Tantalum, in: U.S. Geological Survey (ed.) Mineral Commodities Summaries 2013 13 Metal-Pages Tantalum metal prices, news and information. http://www.metal-

pages.com/metals/tantalum/metal-prices-news-information/. Accessed 3 September 2013 14 Buckingham, D., Cunningham, L., Magyar, M., Papp, J. (2012) Tantalum: Supply-Demand Statistics,

in: U.S. Geological Survey Minerals Information 15 British Geological Survey (2011) Niobium-Tantalum.

http://www.bgs.ac.uk/mineralsuk/statistics/mineralProfiles.html. Accessed 23 August 2013 16 Christmann P, Angel J, Bailly M, Barthélémy F, Benhamou G, Billa M, Gentilhomme P, Hocquard C,

Maldan F, Martel-Jantin B, Monthel J, Compagnie Européenne d’Intelligence Stratégique (CEIS) (2011) Panorama 2010 du marché du niobium: Rapport final. BRGM/RP-60579-FR

17 Firmetal Products - Tantalum: Tantalum Application. http://www.firmetal.com/ta4.asp. Accessed 23 August 2013

14. Tungsten

Tungsten is a very hard, dense, silvery-white metal that forms a protective oxide coating in air. Tungsten is

highly resistant to corrosion, has the highest melting point of all metals and at temperatures over 1650 °C

also has the highest tensile strength. Tungsten is one of the five major refractory metals.

Current supply of tungsten is dominated by Chinese producers. While the price of WO3 with a concentration

of 7.93 kilograms of tungsten per metric ton remained stable at an annual average of 0.15 US$/kg in the

period 2009-2011,*1 the price of tungsten tradable products† is (significantly) higher than it was 6 months

ago, but has started to decrease.2

Figure 1: Distribution of natural tungsten3 and corresponding scores of the producing countries in the




* European market, Metal Bulletin

† Concentrate, ammonium paratungstate (APT), tungsten carbide, tungsten oxide.

Figure 2: Tungsten price development during 1980 – 2011. The unit value is defined as the value in U.S.

dollars of 1 t of tungsten apparent consumption (estimated).8


Hardmetals

Cemented carbides, also called hardmetals, are the main field of application of tungsten.9 The main

constituent of the most widely used cemented carbide is tungsten carbide (WC, making up 85-95% of the

hardmetal), an efficient electrical conductor with hardness close to diamond and with a melting point of

2770 °C. Hardmetals are used to make wear-resistant abrasives and cutters for drills, circular saws, milling

and turning tools used by the metalworking, woodworking, mining, petroleum and construction industries.10

The dominance of WC-based cemented carbides in many different tooling and wear-resistant applications

indicates the difficulty of establishing adequate substitutes for this material. However, WC-based cemented

carbides may be substituted by tool steels, ceramics and cermets in different applications.11,12 Tungsten-

free cemented carbides (TFCC) or cermets are materials based on alternative high-melting compounds (as

compared to tungsten carbide, WC), typically, titanium carbide or titanium carbonitride in metallic binder

phase (Ni and/o Co), possibly with toughening additives.13 Cermets combine the advantages of ceramics

(excellent hardness and resistance to wear and oxidation, as well as low adhesion to the workpiece

material) and metals (strength and impact resistance). The important advantage of TFCC is their

microstructure that contains a complex carbide phase (К-phase) forming a frame around each carbonitride

particle core and providing a strong bond between these hard phase particles and ductile binder metal.

Cermets are also more lightweight as compared to WC-based hard metals14. Cermets are a viable

alternative to the WC-based hardmetals in two major application areas: tribotechnical and machining

applications involving no extreme loads.13

One more solution that is being developed is niobium carbide NbC. BAM Federal Institute for Materials

Research and Testing has in 2012 for the first time established the tribological profile of NbC and advised

that the material can compete with, or even replace tungsten carbide in wear protection. In 2013 BAM

generated data showing that samples of NbC-8Co manufactured at KU Leuven can be successfully used

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as cutting tool and have a potential for substituting tungsten carbide in this application.15 Although niobium

is listed as critical raw material along with tungsten, a technical alternative to tungsten carbide that NbC

offers reduces the dependence on tungsten.

Tool/high speed steels

Historically, tungsten was an important alloying element for tool steels and high speed steels used in the

working, cutting and forming of metal components. These steels must possess high hardness and strength,

combined with good toughness over a broad temperature range. The relative amount of tungsten

consumed in steelmaking declined constantly since the 1930s. Nevertheless, steel is currently the second

largest consumer of tungsten worldwide, but tungsten consumption for steel differs considerably in different

markets, from about 10% in the USA, Europe and Japan to close to 30% in Russia and China.16

The development of controlled atmosphere heat treating furnaces made it practical and cost effective to

substitute part or all of the tungsten with molybdenum, which, combined with alloying with chromium, as

well as with vanadium and nickel, yielded better performance at a lower price. Additions of 5-10%

molybdenum efficiently increase the hardness and toughness of high-speed steels and help to maintain

these properties at the high temperatures generated when cutting metals. Molybdenum provides another

advantage: it prevents, especially in combination with vanadium, softening and embrittlement of steels at

high temperature by causing the primary carbides of iron and chromium to form tiny secondary carbides,

which are more stable at high temperatures.17 The exceptional high temperature wear properties of

molybdenum-containing high-speed steels are ideal for such applications as automobile valve inserts and

cam-rings. Recent development related to niobium carbide and NbC- based materials (see previous

section) can also contribute to the substitution of tungsten-alloyed tool/high speed steels in metal working

and cutting applications. Substitution of tungsten in tool/high speed steels seems thus possible.

Super-alloys

Tungsten-alloyed nickel- and cobalt-based super-alloys possess high-temperature strength and creep

strength, high thermal fatigue resistance, good oxidation resistance, excellent hot corrosion resistance, air

melting capability, air or argon re-melting capability and good welding properties. These super-alloys are

used in aircraft engines, marine vehicles, and stationary power units as turbine blades and vanes, exhaust

gas assemblies and as construction material for furnace parts. Tungsten accounts for solid solution

strengthening, strengthening by formation of intermetallic compounds, and formation of carbides.16

Molybdenum can substitute tungsten in these materials to some extent.17

Another opportunity for substitution in this application is the replacement of super-alloys by ceramic matrix

composites. Ceramic matrix composites (CMCs) made from a silicon carbide/nitride matrix toughened with

coated silicon carbide fibers embedded in the matrix are durable, withstand temperatures as high as 1300

°C and weigh one-third of W-containing super-alloys. In September 2010 General Electric (GE) reported

that the company for the first time had been able to make a CMCs rotating part and tested CMCs-based

turbine blades. GE Aviation plans to start constructing a plant for stationary engine components based on

this technology this year. In February 2012, IHI, leading aircraft engine manufacturer in Japan released a

news article that in 2015 they would finalize mass-production technology of CMCs parts for jet engine

aiming commercialization of CMCs parts in 2020. CMCs appear to be very attractive substitute for super-

alloys as they are strong, tough and can be mass produced.18,19

Mill products

Tungsten mill products, such as lighting filaments, electrodes, electrical and electronic contacts, wires,

sheets, rods etc. or tungsten alloys used for armaments, heat sinks, radiation shielding, weights and

counterweights account for about 10% of tungsten consumption.9,20

Since the beginning of the 20th century, tungsten has illuminated the world, about 4% of the annual

tungsten production is consumed by the lighting industry. It is suited in this application because of its

extremely high melting temperature (~3414 °C), low vapour pressure, high stiffness and excellent creep

resistance at elevated temperatures.9,21 The largest market is still for incandescent lamps but more than

70% of artificial lighting is generated today by discharge lamps, and this portion is steadily increasing.16

Tungsten is used in the form of wires, coils, and coiled coils in incandescent lamps, and as electrode in

low- and high-pressure discharge lamps.

Tungsten is practically the only material used for electron emitters. Although other, more electropositive,

metals would yield higher emission rates, the advantage of tungsten is its extremely low vapor pressure

even at high temperatures. This property is also important for electrical contact materials. While more

conductive metals like copper or silver evaporate (erode) under the conditions of an electric arc, tungsten

withstands these.16

Tungsten is one of the most important components in modern integrated circuitry and tungsten-copper heat

sinks are used to remove the heat of microelectronic devices.

Carbon nanotube filaments, induction technology and light-emitting diodes are potential substitutes for

tungsten-containing products in these applications but replacement of tungsten-based products appears at

present to be extremely difficult at the moment.

Summary

Substitution of WC-based cemented carbides in majority of applications, while potentially possible in many

cases through the successful development of TFCC-technologies, would require significant time since they

currently dominate the market. WC-based cemented carbides, however, seem to be less substitutable in

tribotechnical and machining applications involving extreme loads.

Substitution of tungsten in super-alloys and in applications typical for W-containing super-alloys as well as

in mill products requires further progress in the development of advanced materials, such as CMC and

carbon nanotube-based products. A rapid replacement of W is thus rather problematic. At least 5 years’

time will be needed for bringing CMC parts to the level of commercial production. In contrast,

substitutability of tungsten in tool/high speed steels is, in principle, high.

Figure 3: Distribution of end-uses16 and corresponding substitutability assessment for tungsten. The



References

1 Shedd, K. B. (2013) Tungsten, in: U.S. Geological Survey (ed.) Mineral Commodities Summaries

2013, pp. 176–177

2 Metal-Pages Metal-Pages Tungsten Insider. http://www.metal-pages.com/metals/tungsten/metal-

prices-news-information/. Accessed 30 August 2013

3 Reichl C, Schatz M, Zsak G (2013) World Mining Data: Minerals Production








European Commission

8 DiFrancesco, C., Shedd, K. (2012) Tungsten: Supply-Demand Statistics, in: U.S. Geological Survey

Minerals Information

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