Brannerite is a uranium-titanium mineral that requires aggressive leaching conditions to dissolve. Experiments were conducted to characterize brannerite samples from Australia and study how temperature and acid concentration impact leaching kinetics. At lower temperatures and acidity, brannerite dissolved via a reaction releasing uranium oxide and titanium dioxide. At higher temperatures, a new reaction mechanism was observed involving uranium and titanium sulfate complexes that hydrolyzed to release uranium and form anatase. Dissolution was strongly influenced by temperature and extraction of uranium generally exceeded titanium. The results provide new insights into brannerite leaching reactions and conditions.

1. Mineralogical and chemical
aspects of brannerite leaching
Rorie Gilligan, Aleksandar N. Nikoloski, Artur P. Deditius
AusIMM International Uranium Conference, Adelaide, 9-10 June 2015

2. 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

3. 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

4. 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

5. 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

6. 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

7. The brannerite specimen

8. 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

9. X-ray diffraction analysis
5 10 15 20 25 30 35 40 45 50 55 60 65
2θ (°)
Unleached material

10. 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)

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. Reaction mechanism
• Current reported reaction mechanism1,2:
UTi2O6 + 2 Fe3+ → 2 TiO2 + UO2
2+ + 2 Fe2+
Observed in this study at low temperature and acidity only (Ea = 36 kJ/mol). TiO2 then
attacked by acid:
TiO2 + 2H+ + SO4
2- → TiOSO4
0 + H2O
• Evidence points to a new reaction mechanism at high
temperature3:
UTi2O6 + 2 FeSO4
+ + 4 H+ + 2 SO4
2- →
UO2(SO4)2
2- + 2 Fe2+ + 2 TiOSO4
0 + 2 H2O
Change in reaction mechanism (Ea = 23 kJ/mol). TiOSO4
0 then hydrolyses to anatase:
TiOSO4
0 + 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)

18. 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

19. Further reading
dx.doi.org/10.1016/j.mineng.2014.10.007

20. Further reading
doi:10.1016/j.hydromet.2015.05.016

21. Questions?
Email us
r.gilligan@murdoch.edu.au
a.nikoloski@murdoch.edu.au
a.deditius@murdoch.edu.au