Leaching of Brannerite Ores

AusIMM International Uranium ConferenceAusIMM International Uranium ConferenceLeaching of Brannerite Ores

June 2010June 2010

Speaker: Chris Bucknell

A Member of the Bureau Veritas Minerals Group

Contents

1. Disclaimers

2 Background on leaching Brannerite2. Background on leaching Brannerite

3. Bottle Rolls – as a base line

4 A it ti L h4. Agitation Leaches

a) Effect of Temperature

b) Effect of Grind Size

c) Effect of Free Acid Level

5. What next?

AMDEL - BUREAU VERITAS PRESENTATION – 2010 [email protected]

Disclaimers

� Everything I know about anything can be written on a postage stamp.

� The full data lying behind these results is not detailed as part of this� The full data lying behind these results is not detailed as part of this presentation but is necessary to draw inferences from the results.

� The information presented is based on lab scale not plant scale.

� When I say Brannerite, I am actually talking about the Uranium predominantly contained in the Brannerite present, but also the U in trace intergrowths of Uraninite associated with the Brannerite as welltrace intergrowths of Uraninite associated with the Brannerite, as well as the U in the Thorite.

� All free acid levels are in g/L at the conclusion of the leach unless� All free acid levels are in g/L at the conclusion of the leach unless otherwise specified ie they are discharge values.

� All ORP values are referenced against a Ag/AgCl electrode.

� If the answer to your question is not in this presentation then maybe you misunderstood your question.


History of Brannerite Leaching


History of Brannerite Leaching

� “One of the most difficult uranium minerals to dissolve” Born et al 1975.

� Rate of Brannerite dissolution is directly proportional to sulphuric acid concentration. Born et alBorn et al.

� BUT there is an upper limit to sulphuric acid concentration at which point the dissolution rate decreases ~200g/L. Born et al.

� Four fold increase in extraction from 50 deg C to 70 deg C Born et al� Four fold increase in extraction from 50 deg C to 70 deg C. Born et al.

� Leaching rate increases with increasing ORP until Eh of +575mV. Born et al.

� Leaching on an impure concentrate from Climax, Colorado showed 13% extraction at g p ,room temperature using 10% sulphuric acid. D.R. George 1950 per Clegg et al 1958.

� Radium Hill concentrate was processed at Port Pirie in 98% boiling sulphuric acid. Fitzgerald, M.L. and Hartley, F.R. 1965.

� Ores from the Blind River district, require leaching for 48 hours at 50 dec C with 50g/L free acid. Clegg et al 1958.

� Elliot Lake processed at 48 hours in “hot” sulphuric acid discharging at 40g/L free acid. F C L d B t lF.C Lendrum per Born et al.

� Leaching of Valhalla ore at 50 deg C for 30 hours at 25g/L achieved extraction of 83-85%. Goldney et al 1972.


Bottle Rolls – as a baseline

Bottle Roll Parameters

� Mullock ore grade sample - likely weathered –� Mullock ore grade sample likely weathered head grade 750ppm.

� Temperature ambient.

� Duration 7 days.

� Sample size 1kg� Sample size 1kg.

� Target free acid of 20g/L.

S f /� Sodium chlorate addition of 1kg/T.

� ORP target >550mV.

� Slurry density 40wt%.

� Two particle sizes trialled. One at 100%


passing 38mm and the other at 100% passing 19mm.

Bottle Rolls - as a baseline100 30

80

90

100

%)

25

30

/T)

50

60

70

xtra

ctio

n (%

15

20

mpt

ion

(kg/

30

40

50

Ura

nium

Ex

10

15

cid

Con

sum

0

10

20U

0

5

Ac

Observations

0 1 2 3 4 5 6 7 8

Time (days)U Extraction BR1 @ 38mm Uranium Extraction BR2 @ 19mm Acid Consumption BR1 @38mm Acid Consumption BR2 @19mm

Float concentrateTarget free acid 20g/L

50wt% solidsTemp 90 deg C

Observations1. Overall extraction of U was 22%. Extraction, potentially not flattened out.

2. Acid consumption of 27kg/T.


3. Suggests some relatively easily, but small, amount of extractable uranium present.

Agitation Leaches – Effect of Temperature

Agitation Leach Parameters

� Mullock ore grade sample - likely weathered� Mullock ore grade sample likely weathered – head grade 750ppm.

� Duration 24 hours.

� Sample size 1kg.

� Target free acid of 20g/L� Target free acid of 20g/L.

� Sodium chlorate addition of 1kg/T.

O� ORP target >550mV.

� Slurry density 40wt%.

� One particle size trialled @ 75 microns.

� Range of temperatures 25, 50, 70, 90 deg C.


Agitation Leaches – Effect of Temperature

80

90

100

60

70

80

ract

ion

(%)

30

40

50

rani

um E

xtr

0

10

20Ur

Observations

0 5 10 15 20 25

Time (hrs)U Extraction - 25 deg C U Extraction - 50 deg C U Extraction - 70 deg C U Extraction - 90 deg C

Float concentrateGrind size 40 microns50wt% solidsTemp 90 deg C

Observations1. Extraction effective only at 90 deg C.

2. Optimum extraction at 90 deg C of 93%.


3. Extraction potentially not flattened out.

Agitation Leaches – Acid Consumption

30

35

40

/T)

20

25

30

mpt

ion

(kg/

10

15

Aci

d C

onsu

0

5

0 5 10 15 20 25

A

Observations

Time (hrs)Acid Consumption - 25 deg C Acid Consumption - 50 deg C Acid Consumption - 70 deg C Acid Consumption - 90 deg C

Float concentrateGrind size 40 microns50wt% solidsTemp 90 deg C

1. Reconfirms majority of acid is consumed by gangue.

2. Acid consumed at 90 deg C is double the level at ambient but extraction is 9 times better.

3. If you can keep the free acid low, you will waste less acid on the gangue.


Agitation Leaches – Effect of Grind Size

Agitation Leach Parameters

� Concentrate sample – Head Grade 981ppm� Concentrate sample Head Grade 981ppm.

� Temperature 90 deg C.

D ti 24 h� Duration 24 hours.

� Sample size 1kg.

� Target free acid of 30g/L.

� Sodium chlorate addition of 1kg/T.

� ORP target >550mV.

� Slurry density 50wt%� Slurry density 50wt%.

� Two particle sizes trialled. One at p80 75 microns and the other at p80 40 microns.


Agitation Leaches – Effect of Grind Size

80

90

100

60

70

on (%

)

30

40

50

U E

xtra

ctio

10

20

30

00 5 10 15 20 25

Time (hours)Float concentrateTarget free acid 30g/L50wt% solids

Observations1. Overall extraction of U was the same irrespective of grind size.

75 microns 40 microns50wt% solidsTemp 90 deg C


2. Extraction at 40 microns initially quicker than 75 microns.

3. What if the gangue is so effectively attacked with the high acid levels that grinding could be minimised or eliminated?

Agitation Leaches – Effect of Free Acid

80

90

100

60

70

80

on (%

)

30

40

50

U E

xtra

ctio

10

20

30U

00 5 10 15 20 25

Time (hours)Float concentrateGrind size 40 microns50wt% solids

Observations1. Free acid levels of 12g/L not sufficient to achieve significant extraction.

12g/L 30g/L 40g/L50wt% solidsTemp 90 deg C


2. Extraction accelerated in the initial stages by higher free acid levels.

3. Similar ultimate extraction achieved with target free acid of 30 and 40g/L.

Conclusions

� A temperature of 90 deg C was required before any real extraction of U was observed. Compare this to 70 deg C in Born et al.

� No observed difference in extraction between 50 and 70 deg C where Born et al found a 4 fold increase.

� Maybe you don’t need to grind it as fine as you think, due to the intense acid attack on the gangue.

� The initial extraction rate can be improved by moving from 30g/L to� The initial extraction rate can be improved by moving from 30g/L to 40g/L but with little effect on the overall extraction.

� Keeping the free acid low but above some threshold value (~20-� Keeping the free acid low, but above some threshold value ( 2030g/L), may minimise the acid consumption.

� There is a quite complex interaction between temperature, free acid and grind size to optimise against before finalising your capital decisions.

� Just as all Coffinites are not the same in terms of their leach


� Just as all Coffinites are not the same in terms of their leach behaviour, it unlikely that all Brannerites will be the same.

References

Born, C.A., Queneau, P.B., Ronzio, R.A. (Sept 1975). Processing of Wolframite-Cassiterite Concentrate for Brannerite Removal. TransactionsWolframite Cassiterite Concentrate for Brannerite Removal. Transactions of the Society of Mining Engineers, AIME, Col 258, pp218-221.

Clegg, J.W. and Foley, D.D. (Sept 1958). Uranium Ore Processing. Addison Wesley Publishing Company, Maaaschusetts, USA.

Goldney, N., Canning, R.G. and Gooden, J.E.A. (July 1972). Extraction Investigations with ome Australian Uranium Ores AMDEL presentation toInvestigations with ome Australian Uranium Ores. AMDEL presentation to AAEC Symposium on Uranium Processing.

Fitzgerald, M.L. and Hartley, F.R. (1965) Eighth Commonwealth MiningFitzgerald, M.L. and Hartley, F.R. (1965) Eighth Commonwealth Mining and Metallurgical Congress Vol3. Chapter 9 – Uranium. AMDEL Ltd Report CM 1122/77.


Next Year………

So what about next years conference?

Some real ore examples can be presented from three possible areas:

1. Ion Exchange of Uranium from Carbonate Extractions

2. Selective precipitation of V from Carnotite Extractionsp p

3. Solvent Extraction of Brannerite sourced PLS


Amdel – A Member of the Bureau Veritas Minerals Group


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Leaching of Brannerite Ores