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Mineralogical and chemical aspects of brannerite leaching Rorie Gilligan, Aleksandar N. Nikoloski, Artur P. Deditius AusIMM International Uranium Conference, Adelaide, 9-10 June 2015
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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
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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
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96°C 79°C 63°C 52°C 36°C 25°C
Leaching kinetics
Varied acid concentration, 52°C
Uranium extraction Titanium extraction
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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
