Connections between Phosphate Connections between Phosphate

FertilizerFertilizer Production and the Production and the

Uranium Fuel Cycle Uranium Fuel Cycle

Richard A. Brand

Department of Physics

& Responsible for radiation safety

University of Duisburg-Essen

(Multifos: Tricalcium Phosphate)

Plan• Naturally occurring radioactive materials (NORM)

• Technologically enhanced natural radioactivity:Phosphate Fertilizers & distribution of contaminants

• NORM or Technologically enhanced radioactivity?

• Health effects from use of phosphate fertilizers?

• Example of Uranium and Radium Removal

• Waste Products of Phosphate Fertilizers: phosphogypsum

• Interest in recovering uranium

• Rekindled Interest in recovering uranium and cleaning phosphogypsum

• What should be done

•Naturally occurring radioactive materials (NORM)

Biggest problem high-LET exposure: Radon

Ref: BEIR VII Health Risks from Exposure to Low Levels ofIonizing Radiation, National Research Council 2006

Ref: BEIR VII Health Risks from Exposure to Low Levels ofIonizing Radiation, National Research Council 2006

• Typical risk calculation based on low-LET exposure!

Radiation protection:

Linear no-threshold model generally accepted.Dilution among the general public does not help matters.

Generally little governmental control for materials with less than 1000 Bq/kg.

Approximant limits for no control:U238+ (Th,Pa) 500Bq/kgU238sec (Th, … Po) 10 Bq/kgRa226++ (Rn, … Po) 10 Bq/kg

Ref: Strahlenschutzverordnung 2001

Bundesamt für Strahlenschutz, Berlin

Natural environmental radioactivity

Bundesamt für Strahlenschutz, Berlin

Natural environmental radioactivity

•Technologically enhanced natural radioactivity:Production of Phosphate Fertilizers

Ref: W. E. Falck & D. Wymer, I.A.E.A. Vienna

Sulfuric acid process:

Natural uranium (no daughter isotopes): 25 Bq/mg

All radioisotopes land up somewhere!Radium in the gypsum!

Sulfuric acid process:

Ref: W. E. Falck & D. Wymer, I.A.E.A. Vienna

Natural uranium (no daughter isotopes): 25 Bq/mg

All radioisotopes land up in the fertilizer!

Nitric acid process:

Ref: W. E. Falck & D. Wymer, I.A.E.A. Vienna

Bundesamt für Strahlenschutz, Berlin

•Natural environmental radioactivityOr

Technologically enhancednatural environmental radioactivity?

If much of the uranium in farmed soil is of anthropogenic origin,

why is it listed under “Natural environmental radioactivity”?

Verwendung von Phosphatdüngemitteln

Die in Deutschland eingeführten Rohphosphate, die vorwiegend aus den USA, Nordafrika und Israel kommen,weisen … gegenüber ….der Böden einen bis zu fünfzigfach erhöhten Gehalt an U-238 und Ra-226 auf.

Die spezifischen Aktivitäten der daraus hergestellten mineralischen Phosphatdünger betragen für :

U-238 280 - 920 Bq/kg (TSP max. 3000 Bq/kg), Radium-226 160 - 520 Bq/kg (TSP max. 1150 Bq/kg ) K-40 30 - 6200 Bq/kg…

…

Messungen ergaben für Lagerarbeiter … 2,3 mSv pro Jahr

und … in der Landwirtschaft maximal 1 mSv pro Jahr.

Technologically enhanced natural environmental radioactivityBundesamt für Strahlenschutz, Berlin

•Situation in Germany:

RICHTLINIE 96/29/EURATOM DES RATES vom 13. Mai 1996

Artikel 13

Dosisgrenzwerte für Einzelpersonen der Bevölkerung

(1) Unbeschadet des Artikels 14 sind die in den Absätzen 2 und 3 festgelegten Dosisgrenzwerte für Einzelpersonen der Bevölkerung einzuhalten.

(2) Der Grenzwert der effektiven Dosis beträgt 1 mSv pro Jahr. Allerdings kann unter besonderen Umständen ein höherer Wert der effektiven Dosis pro Jahr zugelassen werden, sofern der Mittelwert über fünf aufeinanderfolgende Jahre 1 mSv pro Jahr nicht überschreitet.

Question: do farmers carry film dosimeters?

•Health effects from use of phosphate fertilizers?One example: Tobacco

Apatite: Ca5(PO4)3(OH,F,Cl)

Source: National Institute of Healthhttp://en.wikipedia.org/wiki/Health_effects_of_tobacco_smoking

… tobacco grown in India averaged only 0.09 pCi per gram of polonium 210, whereas tobacco grown in the United States averaged 0.516 pCi per gram.

One factor in the difference between India and the United States may be the extensive use of apatite as fertilizer for tobacco in the United States…;

The amount of polonium 210 inhaled from a pack of 20 cigarettes is therefore about 0.72 pCi. …independent of any form of filtering or 'low tar' cigarette.

Compared to nonsmokers, heavy smokers have four times greater radioisotope density throughout their lungs.

… the alpha particle dosage from polonium 210 received by smokers of two packs a day was .. 150 times higher than .. from natural background radiation.

Options for the extraction of U from phosphoric acid

1. Precipitation of U from phosphoric acid,

using an organic reagent (e.g. acetone) as dispersant, and ammonium fluoride (NH4F) as precipitant. Reduction of U6+ to U4+ by addition of Fe powder. Recovery of U (for the productionof „yellow cake“) from the precipitate by dissolution in diluted H2SO4 or HNO3 and subsequentpurification by ion exchange or solvent extraction.

2. Ion exchange separation with a chelating resin

(with subsequent elution and precipitation to produce „yellow cake“)

3. Membrane separation of U, using liquid membranes with a strong affinity for U (as yet still in experimental development stage)

4. Froth flotation

complexing U with a surface active agent of hydrophobic nature (froth needs to be purified to produce high grade „yellow cake“)

5. Solvent extraction (capable to be practiced on a large commercial scale)using various synergistic mixtures of organic solvents such as DNPPA (di nonyl phenylphosphoric acid)+TOPO (tri n octyl phosphine oxide), followed by purification and precipitation=> U extraction rates of >90% can be realized

after Singh et al. (2001), Gupta & Singh (2003)Thanks to Sylvia Kratz et al.

Examples of Uranium and Radium Removal

Examples of Uranium and Radium Removal

Environmental Considerations On Uranium And Radium From Phosphate Fertilizers

T.M. CIOROIANU, F. BUNU, D. FILIP, Gh. FILIP

in

Impact of new environmental and safety regulationson uranium exploration, mining, milling and management of its wasteProceedings of a Technical Committee Meeting, 1998, IAEA

Nitric acid attack:1) No gypsum formed.2) all radioisotopes in liquid3) Radium removed by copercipitationwith BaSO44) Uranium and rare earths removedusing solvent extraction

For 1 Kilo fertilizer, 5 kilos phosphogypsum (calcium sulfate)

• Florida: 32 million tones per year

• Most of phosphogypsum lands on stacks

• Much is dumped (oceans) or used in agriculture!

• Efforts to create secondary markets hampered by contamination with radium.

• Possible uses (when not contaminated):

• Construction• Agriculture• Landfill

•Waste Products of Phosphate Fertilizers: phosphogypsum.

•Stacks need to be sealed:similar to uranium mine tailings.•Source of radon.•Can contaminate aquifer system.•Sinkholes

Phosphogypsum Stacks

Disposal into the oceans:

Example:LebaneseChemical Company

GreenpeaceResearchLaboratories2002

• Commercial interest in recovering uranium depends on

market price

Thanks to Ewald Schnug

•Interest in recovering uranium and incleaning up phosphate:

past

Uranium has been recovered from fertilizer production in several countries:

•USA, IMC Global (now Mosaic) up to 1999•Belgium up to 1996•Kazakhstan, Ulbinski & Shevchenko•Pakistan, Multan•Iraq: Al-Quaim•Israel

Commercial recovery ceased due to price of uranium.

Industrial Facilities for Uranium RecoveryInformation from http://www.wise-uranium.org/pfac.html

Outdated!!

• Possible recoverable uranium:

Advantage of U extraction:

Potential U resources in phosphate rock are estimated to range between 15

and 22 Mio t U (WISE, 2000; UIC, 2005). At the current global rate of

consumption (68000 t U/year; UIC, 2005), phosphatic uranium could meet the

global demand for about 220 to 324 years. As a „side effect“, U input into

agricultural soils with mineral P fertilization would be reduced.

Known conventional U resources, on the other hand, are around 3.5 Mio t U,

and will only last for about 50 years (UIC, 2005).

=> Sustainable resource management

Disadvantage: Higher market price for P containing mineral fertilizers

Thanks to Sylvia Kratz et al.

•Interest in recovering uranium for military and clandestine purposes:

•Iraq

al Qaim phosphate plant and uranium extractionfacility (Unit-340).

The unit was designed to produce 54 tonnes of uranium peroxide per year.

http://www.isis-online.org/publications/iraq/alqaim.html

•Interest in recovering uranium for military and clandestine purposes:

•Israel

Israel has also devised a method of extracting uranium from the phosphate deposits in the Negev desert, where there is an estimated 30000 to 60000 tons of uranium in phosphate ores.

Active mining of phosphate deposits takes place in the Negev near Beersheba.

Immediately adjacent to Dimona reactor.

Negev: Contamination of water resources in Southern Israel

http://www.iued.org.il

0.0068 0.0069 0.0070 0.0071 0.0072

R(235U/238U)- isotope ratio

0

10

20

30

40

50

Mean = 0.0072

Std. Dev. = 5.0168E-5

N = 65

Histogram of R(235U/238U)-isotope ratio in different types of samples

Typical R(235U/238U) = 0 .007202

5.1E-5 5.2E-5 5.3E-5 5.4E-5 5.5E-5 5.6E-5 5.7E-5 5.8E-5

R(234U/238U)- isotope ratio

0

5

10

15

20

25

Mean = 5.521E-5

Std. Dev. = 1.2606E-

N = 67

Histogram of R(234U/238U)- isotope ratio in different types of samples

Secular equilibrium

Fig. 10: Frequency histogram (frequency distribution) of R(235U/238U) in fertilisers samples of different type

Fig. 11: Frequency histogram of R(234U/238U) in 67 fertilisers samples of different type

Sattouf et al., (2006) U and Sr isotope ratios in rock phosphates & talk at this symposium

Sample with possibledepleted uranium

•Could be an Interest in recovering uranium for military and clandestine purposes:

Possible to hide U enrichment in fertilizer production:

• Rekindled Interest in recovering uranium:

• Started with $1M AEC-funding of IMC plant in Florida(Time Magazine Apr. 12, 1954)

• Phosphate industry may restart uranium mining as price soars(Tampa Tribune, May 11, 2007, Tampa Florida)

• Florida fertilizer production:1) CF Industries2) Mosaic Corp. (IMC Global + Cargill Cop.)3) Potash Corp.

Other industrial units considering uranium recovery:

1) Yarimca Phosphoric Acid Plant, TurkeySolvent extraction, Önal and AtakRadiation Safety Problems, NATO Science Series

2) Nuclear Materials Corp. EgyptL.A. Guirguis, Can. J. Chem. 61 (1983)

3) Phosphate Research Center, Morocco“Towards a desalination initiative … uranium recovered from Moroccan phosphoric acid production”Lung et al., Int. J. Nuclear Desalination 2005

• Rekindled Interest in cleaning phosphogypsum:

Dr. Bill Burnett surveys the crater-like summitof Florida's largest GYP stack at IMC-Agrico

Presently:

Phosphogypsum stacks capped with plastic

Cost: 10 to 20 M$/stack

Constant monitoring necessary

Danger to aquifer systems

Radon emissionAny use proposed must consider:

• Potential of release of Ra into environment• Radon emitted into atmosphere• Potential re-use and loss of institutional control

Conversion of phosphogypsum to Sulfate fertilizer usingMerseberg process:

Radionuclide flow during the conversion of phosphogypsum to ammonium sulfate

W. C. Burnett et al., Journal of environmental radioactivity 1996

& The Florida Institute of Phosphate Research

• Recovering phosphogypsum for use:

Main problems:

• Application of phosphogypsum, …in building materials has been limited by the presence of minor components that are hazardous, such as radioactive substances, ..,.

The worldwide use of phosphogypsum in buildingmaterials is probably well below 15% of output. In theUS, use was banned in 1990 and in theEuropean Union, it was discontinued by 1992.

Recently, uranium levels in .. phosphogypsum haveincreased due to reduced uranium extraction.

… use in building materials of another type of waste gypsum, generated by flue gas desulphurization, has rapidly increased.

L. Reijnders, Building and Environment 42 (2007) 1036.

Recovering phosphogypsum for use:

. separation techniques may reduce the concentrations of such [radioactive] components.

Higher waste disposal costs, tighter regulations and higher prices for competing virgin minerals could make the use of the purifiedphosphogypsum … in building materials more attractive.

L. Reijnders, Building and Environment 42 (2007) 1036.

In Line Purification of Process Slurries

.. Two methods have been investigated:

(i) supported liquid membrane extraction, and (ii) ion exchange bars.

Both methods have successfully been applied to the solvent-mediated recrystallization of calcium

sulphate.

C. Koopman, G. J. Witkamp, G. M. Van Rosmalen, Removal of heavy metals and lanthanides from industrialphosphoric acid process liquors, Separ. Sci. Technol. 1999, 34(15), 2997-3008

Mechanical, MaritimeAnd Materials Engineering

• Technical means for clean up and recovery exist

• What is urgently needed:

1. Monitoring and limits for total radioisotopes in fertilizers!

2. Necessity for monitoring: avoid uranium black market,utilize an important raw material!

3. Clean-up of radioisotopes in both fertilizer and byproducts.

4. Controlled commercial usage or burial of radioisotopes extracted.

What should be done