Polythionate formation during uranium recovery from sulphide flotation concentrate

Abstract

Uranium recovery by resin-in-pulp (RIP) from sulphide-bearing material was found to be adversely affected by polythionate formation due to partial oxidation of sulphide minerals. Polythionates are loaded more selectively by the conventional strong-base resins used at uranium plants. A study was undertaken to identify whether polythionates are formed during upstream processing, leaching, or ion exchange recovery steps. It was found that polythionate formation could be minimized by shortening of the leach time, optimizing oxidant and acid addition, minimizing delay between leaching and RIP, and maintaining the neutralization and adsorption retention times as short as possible. These insights could prompt the development of mitigation strategies on commercial plants to reduce or avoid the formation of polythionates and the adverse impact it has on uranium recovery.