SULFUR CHEMISTRY IN BACTERIAL LEACHING OF PYRITE

In the case of pyrite bioleaching by Leptospirillum ferrooxidans, an o rganism without sulfur-oxidizing capacity, besides the production of t etra- and pentathionate, a considerable accumulation of elemental sulf ur occurred, A similar result was obtained for chemical oxidation assa ys with acidic, sterile iron(III) ion-containing solutions, In the cas e of Thiobacillus ferrooxidans, only slight amounts of elemental sulfu r were detectable because of the organism's capacity to oxidize sulfur compounds, In the course of oxidative, chemical pyrite degradation un der alkaline conditions, the accumulation of tetrathionate, trithionat e, and thiosulfate occurred, The data indicate that thiosulfate, trith ionate, tetrathionate, and disulfane-monosulfonic acid are key interme diate sulfur compounds in oxidative pyrite degradation, A novel (cycli c) leaching mechanism is proposed which basically is indirect.