Dissolution studies on synthetic coffinite

Coffinite (USiO4) is the second most important uranium ore mineral behind uraninite. In order to improve current processing technology there is a need to gain further understanding on the optimum conditions required for leaching uranium from coffinite. Accurate studies on the dissolution of naturally occurring coffinite however are usually extremely difficult to conduct as this mineral commonly exists only as very fine grains that cannot be readily isolated. Further understanding on coffinite dissolution can, in part, however be achieved through conducting fundamental studies on synthetic coffinite. In this study the influence of a number of key parameters such as oxidation reduction potential, uranium to ferric ratio, temperature and acid concentration on coffinite dissolution were investigated over a 90 minute testing period in a sulphuric acid medium and results analysed via ICP-MS. Results indicate that under the right conditions almost 100 % uranium dissolution from synthetic coffinite can be achieved. Acid concentration in the range studied was found not to have a significant effect on coffinite dissolution. All other parameters in the ranges studied influenced the dissolution of synthetic coffinite however the most significant effect was observed when the temperature was increased