1. Process Chemistry and Mineralogy
of Brannerite Leaching
Rorie Gilligan and Aleks Nikoloski
SAIMM Hydrometallurgy Conference, Cape Town, August 1-3 2016

2. Introduction
• Brannerite, UTi2O6 is the most common refractory
uranium mineral
• Most important uranium mineral after uraninite
and coffinite
• Has a general formula of
(U,Th,REE,Ca)(Ti,Fe3+)2O6
• Thorium and light rare earth elements substitute
uranium

3. Processing of brannerite and ores
• Leached under more aggressive conditions compared to
other U minerals
• >75°C, >25 g/L H2SO4
• Brannerite-rich U ores in Ontario, Canada leached
~75°C
60-75 g/L H2SO4
36-48 h leaching time
• Pressure leaching trialled in South Africa in 1970s-80s

4. Mineralogy
• Associated in ores with titanium minerals
rutile (TiO2), ilmenite (FeTiO3) and titanite
(CaTi(SiO4)O)
• Brannerite in ores is amorphous and altered,
due to its own radioactivity
• Altered brannerite is more susceptible to
leaching

5. Leaching experiments (acid)
• Brannerite leached for 5 hours
• 0.05 mol/L Fe3+
• 0.10-2.00 mol/L H2SO4 or 0.25-1.00 mol/L HCl
• 25-96°C (up to four intermediate values)
• Selected experiments repeated with gangue additives
• 10 g/L fluorapatite or fluorite
• Uranium and titanium dissolution monitored
• Solids characterised by XRD, SEM and EDX

6. Leaching experiments (alkaline)
• Brannerite leached for 24 hours
• 0.010 - 0.025 mol/L Fe3+ as K3Fe(CN)6
• 1.00 mol/L total carbonate as NaHCO3 and Na2CO3
• 50-90°C (three intermediate values)
• Selected experiments repeated with a high-brannerite
ore from Queensland
• Uranium and titanium dissolution monitored
• Solids characterised by XRD, SEM and EDX

7. Brannerite specimen (Cordoba, Spain)
Brannerite interior
Anatase (TiO2)
coating
Anatase and
silica filled
cracks

8. Leaching kinetics – acid
Varied temperature, 0.25 mol/L acid Varied acid concentration, 52°C
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 1 2 3 4 5
Uraniumextraction
Time (h)
H₂SO₄, 96°C HCl, 96°C
H₂SO₄, 52°C HCl, 52°C
H₂SO₄, 25°C HCl, 25°C
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 1 2 3 4 5Uraniumextraction
Time (h)
2.00 M H₂SO₄ 2.00 M HCl
1.00 M H₂SO₄ 1.00 M HCl
0.50 M H₂SO₄ 0.50 M HCl
0.25 M H₂SO₄ 0.25 M HCl
0.10 M H₂SO₄

9. Acid leaching kinetics – effect of apatite
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 1 2 3 4 5
Uraniumextraction
Time (h)
96°C
96°C + fluorapatite
52°C
52°C + fluorapatite
25°C
25°C + fluorapatite
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 1 2 3 4 5Uraniumextraction
Time (h)
100 g/L H₂SO₄
50 g/L H₂SO₄
25 g/L H₂SO₄
100 g/L H₂SO₄ + fluorapatite
50 g/L H₂SO₄ + fluorapatite
25 g/L H₂SO₄ + fluorapatite
Varied temperature, 0.25 mol/L H2SO4 Varied acid concentration, 52°C

10. Leaching kinetics – alkaline
Varied temperature, 2:1 HCO3
-:CO3
2- Varied bicarbonate:carbonate ratio, 70°C
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 4 8 12 16 20 24
Uraniumextraction
Time (h)
90°C
80°C
70°C
60°C
50°C
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 4 8 12 16 20 24Uraniumextraction
Time (h)
4:1 2:1 1:1

11. Final extractions – varied temperature
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 10 20 30 40 50 60 70 80 90 100
Finaluraniumextraction
Temperature (°C)
0.25 M H₂SO₄
0.25 M HCl
1.00 M CO₃²⁻ (24 h)
1.00 M CO₃²⁻ (5 h)

12. Brannerite
characterisation
Si: Red
U: Green
Ti: Blue
Altered zones along
cracks low in U/Ca
Cracks filled with
microcrystalline
anatase
Si/Pb accumulate at
edges of altered zones

13. Post-leach
mineralogy -
sulphuric acid
Altered zones
susceptible to
corrosion.
Note the depth of
corrosion either side
of the anatase
inclusions
Uranium is shown in
green, titanium in
blue

14. Post-leach
mineralogy -
hydrochloric acid
Uranium drawn out
from altered zones
Secondary titanium
oxide forms within
leach pits at higher T
Uranium is shown in
green, titanium in
blue, silicon in red
0.25 M HCl
25°C
0.25 M HCl
96°C

15. Post-leach
mineralogy – apatite
interaction
Varied temperature, 25
g/L H2SO4, apatite
• Residual apatite
associated with gypsum
• No uranium phosphates
were detected
• A phosphorus enriched
titanium oxide rim was
identified on leached
brannerite

16. Post-leach mineralogy (alkaline)
Minimal corrosion
at 50°C
Some pitting at
70°C
Formation of
secondary
anatase on
surface at 90°C
Uranium is shown
in green, titanium
in blue, silicon in
red

17. Conclusions
• Brannerite leaching strongly dependent on temperature
in all lixiviants
• Sulphate media superior to chloride media
• Phosphate minerals inhibit uranium dissolution in acid
• Also contribute to brannerite passivation
• Less of a problem at higher acidities
• Acid and sulphate counteract the effects of phosphate
• Alkaline leaching slow but effective

18. Further reading
• Gilligan, R., Nikoloski, A.N. 2015. The extraction of uranium from
brannerite – A literature review. Minerals Engineering 71, 34-48
• Gilligan, R., Nikoloski, A.N. 2015. Leaching of brannerite in the
ferric sulphate system. Part 1: Kinetics and reaction mechanism.
Hydrometallurgy 156, 71-80
• Gilligan, R., Deditius, A., Nikoloski, A. N. 2016. Leaching of
brannerite in the ferric sulphate system. Part 2: Mineralogical
transformations during leaching. Hydrometallurgy 159, 95-106
• Gilligan, R., Nikoloski, A.N., 2016. Leaching of brannerite in the
ferric sulphate system. Part 3: The influence of reactive gangue
minerals. Hydrometallurgy 164, 343-354

19. Questions?
Contact us
r.gilligan@murdoch.edu.au
a.nikoloski@murdoch.edu.au