UIT GmbH Dresden • Germany

Dynamical Models for Uranium Leaching

H. Kalka

More Info:

H. Kalka, H. Märten, R. Kahnt: Dynamical Models for Uranium Leaching – Production and Remediation Cases

in Uranium in the Environment, B.J. Merkel, A. Hasche-Berger (Editors), Springer Berlin Heidelberg New York, 2006 p. 235-245

© UIT GmbH Dresden H. Kalka

Uranium Miningand Hydrogeology 2005

Dynamical Models for Uranium Leaching

- Production and Remediation Cases -

© UIT GmbH Dresden, Sept. 2005 - 2 -

Dynamical Models

Model Concept1

Production Case2In-situ Leach at Beverley Mine

Remediation Case3Flooding of Königstein Mine

for Uranium Leaching

© UIT GmbH Dresden, Sept. 2005 - 3 -

Dynamical CompartmentModels

mass and charge conservation

high time resolution ∆t ≥ 1 h

local conditionsavailable data

spatial-time structure

modular design with C++ PHREEQC

Thermodynamics

Transport Kinetics

© UIT GmbH Dresden, Sept. 2005 - 4 -

Basic Equations (site-specific)

techn

i

nat

i

adv

ii

dtdm

dtdm

dtdm

dtdm

⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟⎟

⎠

⎞⎜⎜⎝

⎛+⎟⎟

⎠

⎞⎜⎜⎝

⎛=

[ ] ioutiin

ini

N

1jijijij

adv

i cQcQcQcQdt

dm−+−=⎟⎟

⎠

⎞⎜⎜⎝

⎛∑=

→→advection

natural processestechnological processes

© UIT GmbH Dresden, Sept. 2005 - 5 -

ISL Beverley Mine

Australia’s first commercial acid ISL mine

Beverley

since 2000

© UIT GmbH Dresden, Sept. 2005 - 6 -

Wellfield / Wellhouse

injectionextraction

complex flow pattern

averaging overore grades,

hydraulic parameters

© UIT GmbH Dresden, Sept. 2005 - 7 -

First: Analytical Approach

oreore

mdt

dmλ−=

qmmdtdm ore −λ=

0ore m)0(m =

0)0(m =

dissolution flushing

{ }tqt0 ee

qc)t(c λ−− −

−λλ

=

P0Vc=

initial mass

mas

s tra

nsfe

r

© UIT GmbH Dresden, Sept. 2005 - 8 -

{ }tqt0 ee

qc)t(c λ−− −

−λλ

=

Three Parameters

PV/Qq =

flushing rateExample

830 OUt200m =3

P m00030V =h/m200Q 3=

)pH2(bea −⋅=λ

dissolution rate

P00 V/mc =

initial concentration

17 s105.0a −−⋅=2.3b =USiO4

© UIT GmbH Dresden, Sept. 2005 - 9 -

Uranium in the Lixiviant

0

50

100

150

200

250

300

350

400

450

0 30 60 90 120 150 180 210

Time [d]

U3O

8 [p

pm]

WH 8

0

50

100

150

200

250

300

350

400

450

0 30 60 90 120 150 180 210

Time [d]

U3O

8 [p

pm]

WH 9

1d160.0q −=

1d136.0q −=

L/g7.5c0 =

1d016.0 −=λ

L/g4.6c0 =

1d011.0 −=λ

SO4, Cl, Fe, Ca, Si ?

geochemical model

© UIT GmbH Dresden, Sept. 2005 - 10 -

Beverley Mine

ISL ProductionCircuit

© UIT GmbH Dresden, Sept. 2005 - 11 -

ISL Cycle

Orebody

IX Dosage

WH 1

WH 2 WH 3

WH 4

WH n WH

groundwater

diss. precip.

individual dosage

equilibrium with secondary minerals

(reversible)

dissolution of primary minerals

(irreversible)

Compartment Structure

© UIT GmbH Dresden, Sept. 2005 - 12 -

ISL - Numerical Model

04080

120160200240280320360400440480

07.07.03 22.07.03 06.08.03 21.08.03 05.09.03 20.09.03 05.10.03 20.10.03 04.11.03

1,01,21,41,61,82,02,22,42,62,83,03,23,43,6

07.07.03 22.07.03 06.08.03 21.08.03 05.09.03 20.09.03 05.10.03 20.10.03 04.11.03

W9 Data W8 Data W9 Model W8 Model

pH

U3O8

leaching + IX

time behavior ofpH, ORP

U, SO4, Cl, Fe, CaNa, Al, Mg, K, Si

... and material balance in the cycle

silicate minerals

inte

rfer

ing

leac

hing

© UIT GmbH Dresden, Sept. 2005 - 13 -

IX colums (Uranium Recovery)

pregnantLix

barrenLix

Head Tail

Sorption

0%10%20%30%40%50%60%70%80%90%

100%

0 40 80 120 160 200

Resin bed volumes

RHSO4R(SO4)0.5RClR(UO2)0.5SO4

0%10%20%30%40%50%60%70%80%90%

100%

0 40 80 120 160 200

Resin bed volumes

RHSO4R(SO4)0.5RClR(UO2)0.5SO4

Head Tail

Bed Volume Bed Volume

Resin

Loa

ding

eluant(NaCl)Elution

© UIT GmbH Dresden, Sept. 2005 - 14 -

Königstein Uranium Mine

1967 mining1984 acid ISL

A1

A2

A3

A4

B1

B2

B3

AG

BG

C1

C2CG

P_B1

P_B2

P_B3

P_C1

P_C2

P_C3

P_D0

Pfeiler

KS

E2

E1WN

C3

DG WS

Uranium Mine Königstein

pillar

dept

h

cont

rol d

rift

pum

p

Compartment StructureSouth-East Saxony

(near Dresden)

1991 decommissioning2001 start flooding

© UIT GmbH Dresden, Sept. 2005 - 15 -

Internal StructureCo

mpa

rtm. 1

P

Com

partm

. 2

P

F

F

of a Compartment

mobile watermass transport

stagnant watermass production & storage

© UIT GmbH Dresden, Sept. 2005 - 16 -

Mass Transfer (Leaching)

)cc(Qdt

dmdt

dm Fi

Pi

exchi

trans

iFi −+⎟⎟

⎠

⎞⎜⎜⎝

⎛=

)cc(Qdt

dm Fi

Pi

exchi

Pi −−=

0Fi

Pi

exchi /)(Q ρρ−ρΛ=density driven:

long-term sourceshort-term source

)tt(m isekmi −δ+

© UIT GmbH Dresden, Sept. 2005 - 17 -

The Software “Flooding II”

- hydraulics - geochemistry

Königstein

1 hour on PC

2 year forecast

1 000 000 × PhreeqC

© UIT GmbH Dresden, Sept. 2005 - 18 -

Step-by-Step Approach

Model Calibration

Forecast

FirstFlooding

Experiment

SecondFlooding

Experiment

1993

1997

2001

2005Fine Tuning

0

400

800

1200

1600

2000

2400

2800

3200

3600

29.01.01 26.10.01 23.07.02 19.04.03 15.01.04 11.10.04 08.07.05 04.04.06 31.12.06

SulfateSulfate [mg/L]

© UIT GmbH Dresden H. Kalka

0

400

800

1200

1600

2000

2400

2800

3200

3600

Sulfate

0

30

60

90

120

150

180

210

240

270

U

0

200

400

600

800

000

200

29.01.01 26.10.01 23.07.02 19.04.03 15.01.04 11.10.04 08.07.05 04.04.06 31.12.06

FeKönigstein Mine -Forecast

Sulfate [mg/L]

Fe [mg/L]

Uranium [mg/L]pH

15 elements

Time dependence

hydraulics

© UIT GmbH Dresden, Sept. 2005 - 20 -

Evaluate dynamics of mine/process water chemistry

Conclusions

The Models were used to

Select optimized strategies for leaching / remediation

Interpret laboratory and pilot experiments

Systemize chemical and hydraulic field data

Derive a guidance for process monitoring