Uranium Recovery From Highly Saline <i>In Situ</i> Leach Solutions by Ion Exchange

Ion exchange using strong base resins is a well established technology for the recovery and purification of uranium from sulfuric acid leach liquors. Production of uranium at the Beverley Mine in South Australia includes acidic in situ leaching, ion exchange and uranium precipitation. The salinity present in the groundwater results in a relatively high concentration of chloride in the leach liquor reporting to the ion exchange plant. The impact of chloride on the ion exchange process is discussed in this paper. The results presented show that an increased chloride concentration in the lixiviant solution feeding the ion exchange plant leads to increased uptake of chloride by the resin during the loading cycle. At the highest chloride concentration studied (7.5 g/L Cl) chloride took up to 60 per cent of the resin loading sites. The impact of the chloride can be summarised as follows: for a given uranium concentration in the lixiviant feed solution, the uranium loading decreased with increasing chloride concentration; a consequence of decreased uranium loading is an increase in the frequency of elution, with an associated increase in elution reagent costs; and for a given elution efficiency, the uranium concentration in the barrens is expected to increase with increasing chloride concentration.A few options were examined to counteract the impact of chloride: an increase in elution efficiency was targeted to reduce the amount of uranium returning to the loading circuit; increasing the pH improved uranium loading, but this was found to also increase iron extraction; and preliminary screening of alternative resins showed that the higher the theoretical ion exchange capacity of the strong base resin, the higher the uranium loading.Work is continuing on uranium recovery from saline leach liquors, specifically investigating the performance of alternative resins.