Development of Bioreactors for Leaching of Sulfide Minerals

点击翻译按钮获取中文摘要

This report describes a biochemical engineering approach to the bioleaching of sulfide minerals by acidophilic sulfur-oxidizing bacteria in stirred tank reactors operated in a variety of modes.1. Rate data collected for the T.ferrooxidans-elemental sulfur system were analyzed to evaluate the microbial kinetic and stoichiometric parameters, using our kinetic model previously proposed for batch bioleaching. These key parameters for elemental sulfur were similar magnitude to those for metal sulfides such as pyrite (FeS_2) and sphalerite (ZnS). In the leaching of pyrite, moreover, the thermophile A.brierleyi had about four times the specific growth rate of the mesophile T.ferrooxidans, demonstrating that the thermophile is more effective than the mesophile for the pyrite leaching.2. The bioleaching of pyrite was observed to be greatly accelerated by adopting the repeated batch operation (partial replacement of solution) and the semi-batch operation (the solution was continuously fed into a … More nd removed from the reactor, but the pyrite particles stayd in the reactor). To predict the bioleaching kinetics in the semi-batch and repeated batch reactors, the batch model was modified to take into account the removal of free cells from the reactor. The model predictions were consistent with the observed bioleaching rates.3. When the bioreactor was oberated continuously with respect to both liquid and pyrite particles, the mean leaching fraction and the free cell concentration decreased repidly with increasing the dilution rate. There was a sharp maximum in the leaching rate with respect to the dilution rate, and the leaching rate was not directly proportional to the solid-liquid loading ratio in the feed. The batch model was extended to simulate the bioleaching in a continuous flow reactor. The experimental data were predicted well by the continuous model over a wide range of dilution rates and feed solid concentrations.The above-mentioned results provide useful information concerning reasonable design and operation of stirred tank reactors for bioleaching processes of mineral resources. Less