[Oxidation of sulfide minerals by Thiobacillus ferrooxidans]

Samples of natural pyrites and sphalerites were subjected to the action of the mineral medium 9K with 1 g of Fe3+ per litre in the presence and in the absence of Thiobacillus ferrooxidans, and incubated at 28 degrees C under the stationary conditions for 30 days. The chemical composition of the solutions was studied after leaching as well as changes of the surfaces of monoliths. The deepest etching of surfaces with the formation of crusts and films of jarosite, limonite and goslarite occurs upon the combined action of bacteria and Fe3+ in regions of a fine-zonal structure enriched with an isomorphous arsenic admixture which are characterized by a defective weak structure. The pyrite and sphalerite from Charmitan with a higher arsenic and iron content were leached more than the pyrite and sphalerite from Kurgashincan. This was also corroborated by chemical analyses of leaching solutions and by monometric studies of crushed sulfide samples.