Bacterially assisted plant process for leaching uranium ores

The development of a process for uranium extraction in which beds of ore are leached with bacterially regenerated lixiviant is described. The process has been examined at pilot scale and extractions 95% were obtained from ore containing 0.12% U3O8. In the process a series of submerged beds of -3-mm ore was leached continuously for up to 10 days at 500C and pH 1.2. The uranium was recovered by ion exchange and the ferrous solution regenerated by the action of Thiobacillus ferrooxidans at 300C. The overall acid consumption was lower than that used in conventional sulphuric acid leaching. Economic analysis shows cost savings of around $2/kg (1971 prices) as compared with the conventional process, largely because grinding is minimized and a separate solid-liquid separation step is avoided. (author)