NUTRIENTS ENHANCING THE BACTERIAL IRON DISSOLUTION IN THE PROCESSING OF FELDSPAR RAW MATERIALS

Solution phase assays were used to monitor iron reduction activity by a Bacillus sp. during the bioleaching of natural feldspar raw materials under various experimental conditions. The rate of reductive iron dissolution depended on the presence of yeast extract, nitrate and sulphate in the medium. Quinone stimulated the Fe(III) reduction in feldspar raw materials in cell suspensions. The dissolution of iron was enhanced in the presence of technical-grade sucrose and molasses. The modification of the medium with river water and indigenous bacteria increased the bacterial reduction of iron. The Fe content in granite samples treated by bioleaching decreased by about 60%. The process needs controlled conditions for bacterial iron reduction and depends on the mineralogical composition of non-metallic ores. 28 refs.