Brannerite, UTi2O6 is the most important uranium mineral after uraninite, UO2 and coffinite, U(SiO4)1-x(OH)4x. It is also the most common refractory uranium mineral. Ores containing brannerite typically require intense conditions (>50 g/L H2SO4, >75Β°C) compared to other uranium ores for effective uranium extraction to occur. To develop an effective process for the extraction of uranium from brannerite containing ores and improve the extraction from the ores currently being processed, it is necessary to understand the chemistry of the brannerite leaching process.
As this study has shown, brannerite is typically an altered and amorphous mineral, with an extent of alteration depending on the age of the sample and the geological history of the deposit. A sample of brannerite from Cordoba, Spain, was leached over a range of conditions in acidic ferric sulphate media. The sample was filled with cracks and altered zones containing anatase (TiO2). Process parameters studied included temperature (25-96Β°C), acidity (10-200 g/L H2SO4) and the effect of adding selected gangue minerals (apatite, fluorite and ilmenite). The feed and the leached residues were characterised in detail by XRD and SEM-EDX techniques.
The results of this study showed that brannerite dissolution has a stronger dependence on temperature and lesser dependence on free acid concentration. Comparisons between the residues and the feed showed that the altered and amorphous areas of the brannerite sample are more readily leached than crystalline areas. The crystalline areas of the brannerite dissolved congruently, with titanium subsequently precipitating as anatase physically separated from the original brannerite grains
