CHALCOCITE OXIDATION BY CONCENTRATED CELL SUSPENSIONS OF THIOBACILLUS FERROOXIDANS

Suspensions of intact cells of Thiobacillus ferrooxidans catalyze a rapid oxidation of finely ground chalcocite to covellite and soluble copper as shown in the following equation: 2Cu2S + 0» + 2HyS0, ————> 2CuS + 2CuS0, + 2Hy0 This reaction occurs spontaneously, but bacterial action increases the oxidation rate about 40 times. The oxidation reaction consumes protons thus causing an increased pH. Both spontaneous and biologically catalyzed oxidations cease when the pH reaches 4.6 - 4.7. In the presence of bacteria and under experimental conditions as described, a period of only about five hours is required to completely convert 0.3 gm of chalcocite to covellite with a 50% solubilization of the chalcocite copper