BIOLEACHING OF SPHALERITE CONCENTRATE BY THE ACIDOPHILIC THERMOPHILE ACIDIANUS BRIERIEYI

摘要

The kinetics of leaching of sphalerite by the thermophilic Acidianus brierleyi was studied in a batch stirred reactor. Experiments were done at 65 deg C and pH 2.0 on adsorption of A. brierleyi onto sphalerite and bioleaching of sphalerite particles. The distribution of A. bnerleyi cells between the mineral and solution was attained within the first 30 min of exposure to sphalerite, and the equilibrium distribution data were correlated with the Langmuir isotherm. The addition of 0.3 and 1.4 kg/m~3 ferric iron to the A. brierleyi culture resulted in a significant decline in the leaching rates, caused by the formation of iron precipitates such as jarosite. Rate data collected in iron-free leach solutions were analyzed with a batch bioleaching model, in order to determine microbial kinetic and stoichiometric parameters for the growth of A. brierieyi on sphalerite. These growth parameters demonstrated that the rate of bioleaching with the thermophile A. brierleyi is about seven times that with the common leaching mesophile, Thiobacillus ferrooxidans. The batch model and the estimated parameter values were used to simulate the dependence of bioleaching rate on three important operating variables such as initial sphalerite size, initial total cell concentration and initial sphalerite-liquid loading ratio.