Element Cycles and Criticality :

A Focus on Minor Metals

Thomas E. Graedel

Yale University

Center for Industrial EcologyYale School of Forestry & Environmental Studies

Important Points About Minor Metals

• Minor (or “specialty”) metals are vital to many modern technologies, as shown by their fast-changing uses

• Minor metals are mostly available only as by-products

• Minor metals have few good substitutes• Minor metals have very low end-of-life recycling

rates• Minor metals have high levels of criticality

compared with most more common metals

0

40 000

80 000

120 000

160 000

200 0001

96

5

19

67

19

69

19

71

19

73

19

75

19

77

19

79

19

81

19

83

19

85

19

87

19

89

19

91

19

93

19

95

19

97

19

99

20

01

20

03

20

05

20

07

met

ric

ton

s

Year

Global Uses of Antimony, 1965-2009Other

Batteries(industrial)

Batteries(transportation)

Flame retardants

Chemicals

Ceramics and glass

Elements Addressed in the Yale Criticality Project

The “companionality” of metals: the production of many metals is dependent on the production of carrier metals

% of primary production as companion

20 40 5030 60 80 90 10070100

Source: N. T. Nassar, T. E. Graedel, E. M. Harper, Byproduct metals are technologically essential but have problematic supply. Science Advances, in press (2015).

Scrap

W

U

F

C

Min

Mfg

W 2008 (Gg/a) - World

© Yale University 2015

56

56

76

23

0 8

0

22

68

68

7

76 68

68

68

68

0

1

1

Tungsten global

cycle, 2008, Gg/a

(UNEP, Recycling rates of metals, 2011)

End-of-life recycling rates of metals

Source: Graedel, T. E.; Harper, E. M.; Nassar, N. T.; Reck, B. K., On the materials basis of modern society. Proceedings of the National Academy of Sciences 2013, doi: 10.1073/pnas.1312752110.

Substitute performance

20 40 5030 60 80 90 10070100Excellent Poor

The substitutability of metals

Re: Jet engines

Y: Phosphors

Rh: Catalytic converters

Eu: Phosphors

Criticality –

The quality, state, or degree

of being of the highest

importance

Supply Risk

Geological, Technological,

Economic

Depletion

Time

Companion

Metal Fraction

Social &

Regulatory

Policy Potential Index

Human Development

Index

Geopolitical

WGI – Political Stability

Global Supply Concentration

Vulnerability to Supply Restriction

Importance

Material Assets

National Economic

Importance

Substitutability

Substitute Performance

Substitute Availability

Environmental Impact Ratio

Net Import Reliance Ratio

Susceptibility

Net Import Reliance

Global Innovation

Index

Supply Risk

Vu

lne

rab

ility

to

Su

pp

ly R

est

rict

ion

Environmental Implications

Human Health Ecosystems

Cradle-to-gate lifecycle inventory

The 3-Axis Approach to Criticality

Silver criticality – global level

In

Supply Risk

Vu

lner

abili

ty t

o S

up

ply

Re

stri

ctio

n

The three-dimensional criticality of the 62 metals of the periodic table

0

20

40

60

80

100

0 20 40 60 80 100

VSR

G

SRL

Tl

Ag

(a)

Light metals Specialty metals Iron & its principal alloying elements Superalloy metals Copper group

Zinc, tin, lead group Rare earth elements Nuclear energy metals Platinum-group metals

Global-Level Criticality Assessment: Supply Risk and Vulnerability Axes

InSb

As

0

20

40

60

80

100

0 20 40 60 80 100

EI

SRL

Light metals Specialty metals Iron & its principal alloying elements Superalloy metals Copper group

Zinc, tin, lead group Rare earth elements Nuclear energy metals Platinum-group metals

(b)

Global-Level Criticality Assessment: Supply Risk and Environmental Axes

Rh

Pd RuIr

Characteristics of High Criticality

• Largely or entirely available only as a byproduct of more abundant carrier metals

• Used in small quantities in specialized high-technology applications

• Has no suitable substitute or substitutes across its spectrum of uses

A Thought to Take With You

By-product metals rank quite high in long-term criticality. Their recovery from ores (and long-term storage, if necessary) should be strongly encouraged lest moderntechnology become strongly constrained