dow process for uranium recovery from phosphoric acid

Dow Water & Process Solutions

Dow process for uranium recovery from phosphoric acid

Jean-François FerraroGlobal Commercial Development Leader

IAEA Vienna Nov. 4-6th, 2009


Agenda• Background• Challenges• The resin• The process• Future• Q&A


Dow Water and Process Solutions• April 1st, 2009: Dow and Rohm and Haas companies merge together

• Creation of the BU Dow Water and Process Solutions which encompass the membranes and ion exchange resins business of Dow and the ion exchange resin business Rohm and Haas

• ~$0.7-1 billion sales • Focus on hydrometallurgy segment with broad portfolio:• Uniform particle size gel resin for ISL and heap leach

• Uniform particle size MR resin for RIP process• Chelating resins (IDA, APA, picolylamine, Minix)• Process knowledge – numerous partnership in the industry at global level


Background• Extraction of uranium with chelating resin from phosphoric acid studied 30 years ago by Duolite (later Rohm and Haas and now Dow) – Pilot plant at the Negev Nuclear Research Center with Duolite ES467 (1984-86).

• At the time the process was not economical vs. solvent extraction

• In the 90’s uranium recovery from phosphoric acid abandoned due to higher cost vs. Uranium market price.

• More recently Dow has improved the process and the resin used

• Ion Exchange Resins have the advantage to be environmentally friendly and safer than solvent extraction


Uranium price trend


WPA – typical analysis rangeU m g/l 100-300Th m g/l 0-200Fe3+ g/l 2-15Fe2+ g/l 0.1-1.0Al3+ g/l 2-8M g2+ g/l 2-6K+ g/l 1-3Na+ g/l 1-3Si g/l 2-8F- g/l 2-40TOC g/l 0.5-2P205 % 25-35


Challenges

• Selective removal from Uranium• Iron III reduction in iron II• Phosphoric acid concentration• Separation from other ions (Thorium, vanadium…)

• Desired Uranium concentration for further processing

• Resin inventory - Capex


The Resin


Aminophosphonic resin

UO2+

Polystyrene-DVB Macroporous Resin with Aminophosphonic functional groups


Amberlite™ IRC747 - Key properties • Ionic affinity

• H+ >Fe3+ >Al3+>Pb2+ + >UO2+ >Cu2+ >Zn2+ >Fe2+ > Mg2+ > Ca2+ > Cd2+ > Ni2+ > Co2+ > Sr2+ >Na+

• pH• Stability: 0-14• Minimum operating pH: 2

• Temperature• Maximum: 80°C

• Resistance to oxidation• Avoid prolonged contact with oxidants (<1ppm as 02)


Amberlite™ IRC747 vs. Duolite™ C467

Properties Am berlite IRC747 Duolite C467M atrix Styrene divinylbenzene copolym er Styrene divinylbenzene copolym erFunctional groups -CH2-NH-CH2-PO 3Na -CH2-NH-CH2-PO 3NaTotal exchange capacity 1.75 eq/Lr (Na+ form ) 1.00 eq/Lr (Na+ form )M oisture Holding capacity 64-69% (Na+ form ) 65-70% (Na+ form )Harm onic m ean size 520-660µ 500-700µM ax. reversible swelling H+ Na: 45% H+ Na: 35%


LoadingAMP LOADING

F eed S olution H3PO4(30%) + U (200ppm) + Fe2+ (9,5ppm)1 BV/H

0,0

50,0

100,0

150,0

200,0

250,0

0 5 10 15 20 25 30 35 40 45 50BV

UO3

(ppm

)

Am berlite IRC747

Duolite C467

O perating capacity

(9.5g/l)

Operating capacity: 6-10g/Lr


ElutionAMP E LUTION (NH4)2CO 3 1M

0

500

1000

1500

2000

2500

0 1 2 3 4 5 6 7BV

U3O8

(mg/l)

Duolite C467

Am berlite IRC747

Elution of the Uranium can take place with ammonia followed by ammonium carbonate. As shown below, AmberliteTM IRC747 gives not only the highest concentration in the concentrated eluate because of its higher operating capacity. but also a very good elution profile


The process


Requirements

• Adjustment of Phosphoric acid concentration to 30% max.

• Feed: Reduction of Iron III in iron II by metal addition (iron, zinc) or by electrochemical process.

• Temperature 50-60°C• Prevention of feed oxidation (nitrogen blanket)• Loading at 1 BV/h• Elution: neutralization with NH3 followed by elution with a solution of 1M Carbonate de Sodium.


Dramatic effect of iron reduction on loading capacity (>10g/Lr)AMP LOADING

0,0

50,0

100,0

150,0

200,0

250,0

300,0

0 5 10 15 20 25 30 35 40 45 50

BV

UO3

(ppm

)

0

50

100

150

200

250

300

Potentiel (mV)

Fe II : A'lite IRC747_ Fe(II) 8.5g/l + Fe (3g/l)Fe II : InfluentFe III : A'lite IRC747_Fe(III) 8.5g/l + Fe (3g/l)Fe III : InfluentFe II : Potentiel = f(BV)Fe III : Potentiel = f(BV)


Elution: 99% Uranium eluted in 4 BVs

AMP ELUTION (NH4)2CO 3 1M

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0 1 2 3 4 5 6 7 8 9BV

U3O8

(mg/l)

0,0%

20,0%

40,0%

60,0%

80,0%

100,0%

% U3O8 eluated

Elution Cycle n°1 - Fe II

Elution Cycle n°1 - Fe III

% Elué Fe II

% Elué Fe III


Merry go round system

• 4 columns systems• Two in series for loading and one in regeneration or standby

• Fourth column with a strong base resin for over-concentration

ElutionNH3

Na2CO3

Uranium (2-4g/l)

FeedRaw WPA

SBAConcentration step(Ambersep™ 400)

PurifiedPhosphoric acid

2 31

(20-40g/l)


Simulated Moving Bed system

• Advantages:• Continuous process

• Sharper separation: for instance Uranium vs. Thorium

• Higher purity• Less resin inventory

• Less waste


What next?

• Several joint development programs with key partners

• Uniform particle size capability

• New chelating resin with higher selectivity vs. Iron


Q&A


Thank you!

dow process for uranium recovery from phosphoric acid

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