2015-06-05 AusIMM U conference presentation Final

Mineralogical and chemical

aspects of brannerite leaching Rorie Gilligan, Aleksandar N. Nikoloski, Artur P. Deditius

AusIMM International Uranium Conference, Adelaide, 9-10 June 2015

Introduction

Brannerite, UTi2O6 is a multiple oxide of uranium and

titanium

Has a general formula of (U,Th,REE,Ca)(Ti,Fe3+)2O6

Thorium and light rare earth elements substitute

uranium

Associated with titanium minerals

Requires aggressive conditions to leach

Important U mineral in uranium/REE deposits

Brannerite in Australia

Minor U mineral at Olympic Dam (SA) and Ranger (NT)

Major U mineral in Valhalla, Skal and others, Mount Isa, QLD

Major U mineral at Curnamona province, Crocker Well, Mount Victoria, SA

Image from: http://www.australianminesatlas.gov.au/aimr/commodity/uranium.html

Brannerite in Australia

Minor U mineral at Olympic Dam (SA) and Ranger (NT)

Major U mineral in Valhalla, Skal and others, Mount Isa, QLD

Major U mineral at Curnamona province, Crocker Well, Mount Victoria, SA

Image from: http://www.australianminesatlas.gov.au/aimr/commodity/uranium.html

Mount Isa

Brannerite in Australia

Minor U mineral at Olympic Dam (SA) and Ranger (NT)

Major U mineral in Valhalla, Skal and others, Mount Isa, QLD

Major U mineral at Curnamona province, Crocker Well, Mount Victoria, SA

Image from: http://www.australianminesatlas.gov.au/aimr/commodity/uranium.html

Mount Isa

Curnamona Province

Leaching experiments

Brannerite leached in ferric sulphate and

sulphuric acid

2.8 g/L Fe3+

10-200 g/L H2SO4

25-96°C (four intermediate values)

Uranium and titanium dissolution monitored

Solids characterised by XRD, SEM and EDX

The brannerite specimen

Compositions of different brannerite

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Mass

%

U Ti Th Pb Ca Fe Si This study

X-ray diffraction analysis

5 10 15 20 25 30 35 40 45 50 55 60 65

2θ (°)

Unleached material

X-ray diffraction analysis

5 10 15 20 25 30 35 40 45 50 55 60 65

2θ (°)

Unleached material

Synthetic brannerite, Szymanski and Scott (1982)

X-ray diffraction analysis

5 10 15 20 25 30 35 40 45 50 55 60 65

2θ (°)

Unleached material

Anatase - PDF 21-1272

Synthetic brannerite, Szymanski and Scott (1982)

Thourutite, heated - PDF 14-0327

Sample characterisation

This sample consists of

two major phases and >2

minor phases

U-Ti oxide with traces of

Ca, Pb, Fe – brannerite

Ti oxide with traces of U,

Pb, Si, Ca, Fe – anatase

Minor phases include

uranium oxides and

gangue silicates

Elements:

Silicon

Uranium

Titanium

Minerals:

Silicate

gangue

Uranium

oxide

Brannerite

Anatase

Leaching kinetics

Varied temperature, 25 g/L H2SO4

Uranium extraction Titanium extraction

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4 5 Time (h)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4 5 Time (h)

96°C 79°C 63°C 52°C 36°C 25°C

Leaching kinetics

Varied acid concentration, 52°C

Uranium extraction Titanium extraction

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4 5 Time (h)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4 5 Time (h)

200 g/L H₂SO₄ 100 g/L H₂SO₄ 50 g/L H₂SO₄ 25 g/L H₂SO₄ 10 g/L H₂SO₄

SEM (BSE) images - particles

25°C 36°C 52°C

63°C 79°C

96°C

Backscattered electron images.

Particles leached in 50 g/L H2SO4

Extraction:

34% U, 31% Ti 50% U, 46% Ti 75% U, 68% Ti

88% U, 80% Ti 95% U, 86% Ti 98% U, 82% Ti

Cross section SEM (BSE), element maps Particles leached in 50 g/L H2SO4

Elements:

Uranium,

Titanium

Minerals:

Brannerite,

Anatase

52°C 63°C

25°C

Reaction mechanism • Current reported reaction mechanism1,2:

UTi2O6 + 2 Fe3+ → 2 TiO2 + UO22+ + 2 Fe2+

Observed in this study at low temperature and acidity only (Ea = 36 kJ/mol). TiO2 then

attacked by acid:

TiO2 + 2H+ + SO42- → TiOSO4

0 + H2O

• Evidence points to a new reaction mechanism at high

temperature3:

UTi2O6 + 2 FeSO4+ + 4 H+ + 2 SO4

2- →

UO2(SO4)22- + 2 Fe2+ + 2 TiOSO4

0 + 2 H2O

Change in reaction mechanism (Ea = 23 kJ/mol). TiOSO40 then hydrolyses to anatase:

TiOSO40 + H2O ↔ TiO2(anatase) + 2 H+ + SO4

2-

1. Gogoleva, E. M. 2012.The leaching kinetics of brannerite ore in sulfate solutions with iron (III). J Radioanal Nucl Chem 293 (2012) 185-191

2. Smits, G. 1984. Behaviour of minerals in Witwatersrand ores during the leaching stage of the uranium extraction process. Applied Mineralogy, 599-616

3. Gilligan, R., Nikoloski, A.N. The leaching of brannerite in the ferric sulphate system - Part 1: Kinetics and reaction mechanism. Hydrometallurgy (Accepted)

Conclusions

Brannerite was observed to dissolve under

practicable conditions

New information on the reaction mechanism

for brannerite leaching

Brannerite dissolution is strongly dependent on

temperature, slightly on acidity

Uranium extraction exceeds titanium

extraction

Further reading

dx.doi.org/10.1016/j.mineng.2014.10.007

Further reading

doi:10.1016/j.hydromet.2015.05.016

Questions?

Email us

[email protected]

[email protected]

[email protected]