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URANIUM URANIUM EXTRACTION FROM TUNISIAN EXTRACTION FROM TUNISIAN PHOSPHORIC ACID PHOSPHORIC ACID VIENNE NOVEMBER 5, 2009 VIENNE NOVEMBER 5, 2009 Presented by M. Presented by M. Chaker Chaker CHTARA Manager Scientific Research GCT CHTARA Manager Scientific Research GCT

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URANIUMURANIUM EXTRACTION FROM TUNISIAN EXTRACTION FROM TUNISIAN PHOSPHORIC ACIDPHOSPHORIC ACID

VIENNE NOVEMBER 5, 2009VIENNE NOVEMBER 5, 2009

Presented by M. Presented by M. ChakerChaker CHTARA Manager Scientific Research GCT CHTARA Manager Scientific Research GCT

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The area of Tunisia : 163 610 km2

Population : 10.2 million (2006) The CPG currently operates seven open pits and one underground mine.Annual production : 8 million tonnes of phosphate merchant placing Tunisia in the 5th among the world producers of phosphate. After a long experience of exporting raw phosphate, Tunisia has turned towards the transformation and recovery of this mineral by the establishment of a local industry to produce phosphoric acid and mineral fertilizers. The GCT has four industrial parks located in SFAX, M'DHILLA (plants TSP), GABES (phosphoric acid plants, DAP, DCP and ammonium nitrate) and SKHIRA(phosphoric acid plant).Tunisia is the second country in the world to enhance a large percentage of its phosphate production (nearly 80%).

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SUMMARY• POTENTIAL RESSOURCES OF PHOSPHATESPOTENTIAL RESSOURCES OF PHOSPHATES

• POTENTIAL RESSOURCES OF URANIUM FROM PHOSPHORIC ACIDPOTENTIAL RESSOURCES OF URANIUM FROM PHOSPHORIC ACID

• RECOVERY OF URANIUM FROM PHOSPHORIC ACID RECOVERY OF URANIUM FROM PHOSPHORIC ACID (GCT EXPERIENCE)(GCT EXPERIENCE)

• DEPADEPA--TOPO PROCESSTOPO PROCESS

• CHALLENGESCHALLENGES

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POTENTIAL RESSOURCES OF POTENTIAL RESSOURCES OF PHOSPHATESPHOSPHATES

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URANIUM FROM PHOSPHATE ROCKPhosphate Reserves: about one billion tonnes ;Tunisian Phosphate rock is located in the south western and in the north eastern of the country;A major proportion of this phosphate contains uranium: 40 to 50 ppm; Phosphate Production in 2008: 8 million tons/y with 50 ppm of U;The mine of future Sraa Ouertane (ten billion tonnes)reserves contains 100-140 ppm.

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URANIUM IN PHOSPHATESPAYS U3O8 (ppm)

Min MaxAlgérie 110 140Brésil 50 250Egypte 70 140Jordanie 50 150Maroc 90 160Sénégal 120 180Syrie 60 160Togo 80 100Tunisie 30 150*US Floride 100 150US C. Nord 60 80

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URANIUM IN TUNISIAN PHOSPHATESA recent chemical analysis of uranium in phosphates A recent chemical analysis of uranium in phosphates Tunisian (29Tunisian (29--30% P30% P22OO55) has identified the values in the ) has identified the values in the following table:following table:

57 4962

140

020406080100120140160

Metlaoui Mdhilla Moulares Sraa Ouertane

U ppm

Phosphate

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STATE OF OXIDATION OF U IN THE PHOSPHATES

Uranium Uranium isis presentpresent in the phosphate substitution in in the phosphate substitution in calcium Cacalcium Ca2+2+ in the in the crystalcrystal latticelattice of apatite. of apatite. This uranium This uranium isis foundfound in the in the tetravalenttetravalent oxidationoxidationstates (+4) (UOstates (+4) (UO22) and ) and hexavalenthexavalent (+6) (+6) formform (UO(UO22))2+2+ in in variousvarious proportions. proportions.

WeWe have: have:

Uranium UUranium U+4+4 substitutedsubstituted 2 calcium ions Ca2 calcium ions Ca2+2+, , Uranium UUranium U+6+6 substitutedsubstituted 3 calcium ions Ca3 calcium ions Ca2+ 2+ ..

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POTENTIAL RESSOURCES OF POTENTIAL RESSOURCES OF URANIUM FROM PHOSPHORIC ACID URANIUM FROM PHOSPHORIC ACID

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INTRODUCTIONThe GCT annually processes approximately 7 million tons The GCT annually processes approximately 7 million tons of phosphates, to produce phosphoric acid and fertilizers. of phosphates, to produce phosphoric acid and fertilizers. This transformation will take place through its various This transformation will take place through its various phosphoric acid unit operating with the SIAPE Di Hydrate phosphoric acid unit operating with the SIAPE Di Hydrate process. process.

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GCT PA PRODUCTION IN 2008Total P2O5 acid capacity = 1.650 million tons/year

1.020 million t/y of P2O5 acid in 5 separate units at Gabes;0.150 million t/y of P2O5 acid in 1 unit at M’dhilla;0.120 million t/y of P2O5 acid in 1 unit at Sfax;0.360 million t/y of P2O5 acid in 2 units at Skhira.

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URANIUM IN TUNISIAN PHOSPHORIC ACID

A major proportion of this acid contains uranium: 40 to 50 ppm in the major quality;

The gisement Sraa Ouertane contains 100-140 ppm with 20-25%P2O5

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GCT CURRENT POTENTIALAssumes phosphate contains 50 ppm of U and recovery

is 90% the quantity of U recovery is 265T U/year

During the process, the uranium content of the phosphate ores is preferentially transferred to the phosphoric acid. The uranium material balance is favourable to transfering the uranium to the aqueous phase: Phosphoric acid

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GCT POTENTIAL 2011

New Production Plant in Service: 1.500 million T/year of PA

Total GCT Uranium Potential: 332 TU/year

Assumes phosphate contains 50 ppm of U and recovery is 90%

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RECOVERY OF URANIUM FROM RECOVERY OF URANIUM FROM PHOSPHORIC ACID PHOSPHORIC ACID (GCT EXPERIENCE)(GCT EXPERIENCE)

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PHOSPHORIC ACID PRODUCTION

To extract Uranium from phosphate rock we must produce in the first time phosphoric acid.Phosphoric acid is produced by contacting phosphate ores with sulfuric acid.

Ca10F2(PO4)6+10H2SO4+20H20 2HF+6H3PO4+10CaSO42H2O

Uranium balances established after the sulfuric attack of phosphates, show that 85 to 90% of uranium content in these phosphates are found in the phosphoric acid and a small amount is lost in the phosphogypsum.

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URANIUM IN PHOSPHORIC ACID

During the process, the uranium content of the phosphate ores is preferentially transferred to the phosphoric acid.

The uranium material balance is favourable to transfering the uranium to the aqueous phase: Phosphoric acid

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• The parameters which relate to the process of transformation must ensure a maximum efficiency of P2O5 dissolved in the liquid phase.

• These parameters are not necessarily the same ones that guarantee a maximum rate of passage of uranium in aqueous phase.

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Élément Acide Phosphoriquemini max

P2O5 % 25 26CaO % 0,1 0,5MgO % 0,5 0,7SiO2 % 0,2 0,4H2SO4 % 0,8 1,5Fe2O3 % 0,2 0,3Al2O3 % 0,3 0,4F % 0,7 1C. Org % 0,035 0,05Uranium ppmUranium ppm 3535 4545

PhosphatePhosphateÉlément Phosphate Lavé

mini maxP2O5 % 28,6 29,8CaO % 49 51MgO % 0,45 0,7SiO2 % 2,5 4,5CO2 % 6 8SO3 % 2,50 4,5Fe2O3 % 0,3 0,38Al2O3 % 0,6 0,8F % 3,2 3,6C. Org % 0,5 1,4

Uranium (ppm)Uranium (ppm) 5050 6060

Acide phosphoriqueAcide phosphoriqueCHEMICAL ANALYSES

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PROCESS IMPLEMENTATIONPROCESS IMPLEMENTATIONIn general, the processes of liquidIn general, the processes of liquid--liquid differ by: liquid differ by:

The nature of the solvent ; The nature of the solvent ; The extraction technique implementation. The extraction technique implementation.

The main objective is to ensure intimate contact between The main objective is to ensure intimate contact between the organic and aqueous phases to maximize the recovery the organic and aqueous phases to maximize the recovery yield of solute (uranium). yield of solute (uranium).

To do this, existing facilities are classified in two types: To do this, existing facilities are classified in two types: Mixer settler ; Mixer settler ; Columns packed mobile or fixed.Columns packed mobile or fixed.

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SOLVENT USEDSOLVENT USEDThe The solventssolvents usedused in in industrialindustrial scalescale are the are the followingfollowing: :

DEPADEPA--TOPO:TOPO: DiethylhexylDiethylhexyl PhosphoricPhosphoric AcidAcid and and Tri Tri

OctylOctyl Phosphine Phosphine OxideOxideOPAP:OPAP: OctylOctyl PhenylPhenyl PhosphoricPhosphoric AcidAcidOPPA: OPPA: OctylOctyl PyroPyro PhosphoricPhosphoric AcidAcid

AccordingAccording to the IAEA report to the IAEA report publishedpublished in 1989, in 1989, the the methodmethod basedbased on the DEPAon the DEPA--TOPO TOPO solventsolventthisthis technologytechnology the the mostmost efficient. efficient.

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BACKGROUNDBACKGROUNDThe GGT was interested in the recovery of uranium from The GGT was interested in the recovery of uranium from phosphoric acid twice: phosphoric acid twice:

In the late '70s, the program was motivated primarily by In the late '70s, the program was motivated primarily by rising uranium prices and mastery of new technologies in rising uranium prices and mastery of new technologies in the field of phosphoric acid;the field of phosphoric acid;

From 2008 a new program was initiated.From 2008 a new program was initiated.

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RESULTS OF PREVIOUS TESTSRESULTS OF PREVIOUS TESTSRESULTS OF PREVIOUS TESTSThe experience of GCT in the extraction of uranium The experience of GCT in the extraction of uranium from phosphoric acid, dates back to 1978.from phosphoric acid, dates back to 1978. Although a Although a considerable amount of research and development, considerable amount of research and development, tthe he research carried out has enabled:research carried out has enabled:

Period 1978Period 1978--1981: achievement test extraction of 1981: achievement test extraction of uranium from Tunisian acid microuranium from Tunisian acid micro--scale pilot process scale pilot process by by GardinierGardinier PUK;PUK;Period 1982Period 1982--1984: Installation and implementation of 1984: Installation and implementation of a pilot plant at a pilot plant at GabesGabes..

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DESCRIPTION OF PILOT UNIT DESCRIPTION OF PILOT UNIT

This pilot unit dimensioned for a capacity of 200 This pilot unit dimensioned for a capacity of 200 l/hl/h of of dilute acid (28% Pdilute acid (28% P22OO55) at the entrance is composed of ) at the entrance is composed of two sections: two sections:

Acid pretreatment section;Acid pretreatment section;A section of extraction and stripping of uranium.A section of extraction and stripping of uranium.

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The process is based on the following principles: The process is based on the following principles:

The solvent used is OPPA (The solvent used is OPPA (OctylOctyl PyroPyro Phosphoric Acid) Phosphoric Acid) in kerosene;in kerosene;Uranium is extracted from the acid to 28% PUranium is extracted from the acid to 28% P22OO55;;Uranium is mined by valence 4; Uranium is mined by valence 4;

The technique of extraction of uranium is based on the The technique of extraction of uranium is based on the use of a battery of 4 mixers settlers. use of a battery of 4 mixers settlers.

PROCESS DESCRIPTION PROCESS DESCRIPTION PROCESS DESCRIPTION

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The process is based on the following steps:The process is based on the following steps:Pretreatment and Conditioning acid;Pretreatment and Conditioning acid;Extraction of Uranium;Extraction of Uranium;Precipitation of uranium tetra fluoride: UFPrecipitation of uranium tetra fluoride: UF44;;Separation of three phases: Aqueous (HF) organic Separation of three phases: Aqueous (HF) organic (solvent), Solid (UF(solvent), Solid (UF44) by centrifugation;) by centrifugation;Washing UFWashing UF44; ; Washing and recycling of the solvent;Washing and recycling of the solvent;Recycling of the aqueous HF;Recycling of the aqueous HF;Purification of uranium to the stage "ADU".Purification of uranium to the stage "ADU".

STEPS OF THE PROCESSSTEPS OF THE PROCESSSTEPS OF THE PROCESS

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The research conducted at the pilot plant have:The research conducted at the pilot plant have:

To study the adaptation process to the Tunisian To study the adaptation process to the Tunisian phosphoric acid; phosphoric acid; To define the operating parameters, material balances and To define the operating parameters, material balances and

consumption of specific chemicals consumed;consumption of specific chemicals consumed;To study the compatibility of the acid (without uranium) To study the compatibility of the acid (without uranium)

with existing downstream manufacturing; with existing downstream manufacturing; Provide staff training in techniques of extracting uranium.Provide staff training in techniques of extracting uranium.

RESULTS OF WORKRESULTS OF WORKRESULTS OF WORK

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DEPADEPA--TOPO PROCESSTOPO PROCESS

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PROCESS DESCRIPTION

Pretreatment of acid;Pretreatment of acid;First cycle extraction;First cycle extraction;First stage of stripping;First stage of stripping;Second cycle extraction;Second cycle extraction;Second round of stripping;Second round of stripping;Precipitation and purification of uranium;Precipitation and purification of uranium;Solvent regeneration.Solvent regeneration.

The DEPAThe DEPA--TOPO process includes the following main steps:TOPO process includes the following main steps:

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PROCESS CONDITIONSThe solvent used is the DEPA-TOPO, it is a mixture of two solvents to a given proportion. This combination provides a synergistic effect in favor of a more efficient recovery of uranium and better selectivity;Uranium is extracted from the acid at a concentration of P2O5 < 30% ; Uranium is extracted by valence 6; The recovered uranium is in the form of U3O8.

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ADVANTAGES OF THE DEPAADVANTAGES OF THE DEPA--TOPO PROCESSTOPO PROCESS

This process has advantages over the OPPA process. This process has advantages over the OPPA process. These advantages are mainly:These advantages are mainly:

The solvent used is more stable and more selective;The solvent used is more stable and more selective;Uranium is extracted by valence 6;Uranium is extracted by valence 6;

Uranium is recovered directly in the form of UOUranium is recovered directly in the form of UO22 or or UU33OO88 conform to standards of purity required. conform to standards of purity required.

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CHALLENGESExtraction Uranium from MG phosphoric acid;Solvent extraction able to extract Uranium with more efficiency;Extraction Uranium by a novel technology in our pilot purification plant based on Pulsed column and not mixer settler method.

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Thank you for your attention