Assessment of amenability of sandstone-hosted uranium deposit for in-situ recovery

Laboratory studies to characterise mineralogy and hydrometallurgical behaviour can be used as an essential and critical sub-component of field leach trials to reduce the risk associated with the implementation of an in-situ recovery process. Sample characterisation, bottle-roll leach tests, column leach tests and ion-exchange studies were conducted on samples from the sandstone-hosted Bennet Well deposit (Yanrey Station) in Western Australia, to obtain an understanding of the ore properties, leach behaviour and lixiviant/oxidant options, uranium recoveries and impurity treatment with a view to determining the suitability of this deposit for in-situ recovery processing. Drill core samples from the deposit contained coffinite, were suspected to contain autunite, and contained uranium associated with coal particles and titanium oxides. The main gangue mineral was quartz, and moderate quantities of K-feldspar, kaolinite and muscovite were present. Bottle-roll and column leach tests indicated that sulfuric acid or a carbonate/bicarbonate lixiviant would be suitable for leaching, with the former yielding a higher maximum uranium extraction. Acid column tests on five drill core samples from different deposit locations yielded between 57% and 84% uranium extraction, and 32% to 69% uranium extraction was achieved for the carbonate column leach tests, without oxidant addition. Oxidant addition increased the uranium extraction to 93%-98% for the acid column leach tests and 38%-70% for the carbonate column leach tests, however, oxidant addition complicates downstream processing. Column leach tests yielded lower recoveries compared with the bottle-roll leach tests and recoveries are expected to be lower for a field-scale implementation. A number of ion-exchange resins were found to be suitable for uranium recovery, with up to 100% loading and elution achieved in the acid and carbonate systems. This approach provides an experimental guideline for similar application to deposits that may be amenable to ISR processing.