The release of sulphidic minerals from aluminosilicates by Bacillus strains

The influence of bacterial strains mixtures of Bacillus species on the stru cture of mineral samples in the form of polished sections and granulated pr oducts subsequently to ore dressing at the Banska Hodrusa deposit was inves tigated. These bacterial strains were isolated from a mining dump near Bans ka Stiavnica and from a kaolin pit near Horna Prievrana. The ability of our bacteria to destroy some silicates and to produce the re lease of several metal cations from their structure was confirmed by morpho logical changes of the miner al surface in comparison with the control samp les after 20 days of bioleaching. In the polished sections quartz and silic ates were the predominant minerals, whereas sphalerite, galena, rhodonite, pyrite and finely disseminated gold were present in traces. The main metabo lites of our bacterial strains detected by the capillary isotachophoresis m ethod were acetic acid, butyric acid, pyruvic acid, lactic acid and formic acid. The biodegradation ability of our strains was also confirmed by X- Ra y analysis and by the removal of individual metal cations from the samples determined by atomic absorption spectrometry. These methods showed the diff erent activity of these strains on mineral samples. The mixture of Bacillus strains extracted 39% Si, 60% Pb, 43% Zn and 32% Cu from flotation concent rate, 33% Si, 75% Pb, 76% Zn, 76% Cu and 82% Mn from post-flotation waste, 30% Si, 59% Pb, 35% Zn, 56% Cu, 78% Mn, 37% Al and even 30 % Au from gravit ational concentrate.