BIOLOGICAL LEACHING OF SHALES: BLACK SHALE AND OIL SHALE

The purpose o f this study was to evaluate the oxidauve dissolution o f a black (dictyonem a) shale and processed concenrrates from a prospecnve mine site in Toolse, Estonia.Black shaJes are sedimentary rocks com posed m ainly o f illite, quartz, feldspars, pynte, and kerogen.Some Estonian black shale deposits also contain high levels of U. V, and Mo as well as other microelem ents Ln Estonian phosphate mines, black shales tend to overlie phosphorite deposits.At mine sites, these shales are stored in waste heaps which become potenoal sources o f acidic discharge with high concentrations o f dissolved metals.Acid leaching under both abiotic conditions and with enhanced bactenai action (Thiobocillus fermoxuLms and Thiobocillus ihioondansI were assessed in this study The leaching was monitored by m easurem ent of chemical changes in leach solutions and examination o f solid leach residues by X-rav diffraction The shale concentrate with the highest pynte content showed the most potential for biological form anon o f sulfunc acid, and acidophilic thiobacilii also enhanced the dissolution o f metals.