Leaching uranium from carbonate ore using Thiobacillus thiooxidans (S-V)

Abstract

BIOSIS COPYRIGHT: BIOL ABS. By appropriate enrichment of solid and liquid samples collected from mining, processing, overburden and process waste of uranium ore, a number of acidophilic, chemoautotrophic sulphur oxidizers resembling Thiobacillus thiooxidans have been isolated. These were compared for their rate of sulphur oxidation and the best strain, T. thiooxidans (S-V) was used for leaching studies. Carbonate bearing sandstone uranium ore found in Pakistan requires 10-13 g H2SO4 for every 100 g ore to solubilize above 90%. When the selected strain, T. thiooxidans (S-V) was grown on mineral salt medium supplied with sulphur as the source of energy, it could produce 25 g/l H2SO4 in the medium dropping the pH from 2.5 to 0.87 in 18 days. A suspension of 5% w/v slurry of uranium ore in mineral salt medium supplied with elemental sulphur (1%) and sodium thiosulphate (1%) resulted in a pH of 5.9. Using controlled conditions in a bioreactor (Biostat E), the pH dropped to 2.1 within three days after i