Bioleaching behavior and surface property of pyrites in different metallogenic conditions

The bioleaching behaviors and surface properties of pyrites in two metallogenic conditions by Sulfobacillus thermosulfidooxidans were investigated by adsorption tests, zeta-potential measurements and bioleaching experiments. It is found that there were significant differences in the microorganism adsorption capacity, electrokinetic properties and bioleaching behaviors for the two pyrites. The S. thermosulfidooxidans adsorption capacity on high temperature hydrothermal (hy_high_temp) pyrite is larger than that on sendimentary coal (sed_coal) pyrite. It may be that more extracellular polymeric substances (EPS) is produced when it is difficult for microorganism to make use of hy_high_temp pyrite as source of energy, and get leaching bacteria attached to pyrite by means of EPS. The zeta-potential measurements indicated that zeta-potential value of hy_high_temp pyrite was higher than that of sed_coal pyrite in pH range of 2–10. After interacting with cells, the IEP (Iso-Electric Point) of hy_high_temp pyrite shifted obviously to that of bacterial. In contrast, the IEP of sed_coal pyrite remained unchanged nearly. The bioleaching results showed that hy_high_temp pyrite did not dissolve and the leaching extent was only 0.82%, while that of sed_coal pyrite was 34.59%. Attempts were taken to illustrate the remarkable difference between bioleaching results of two pyrites from a semiconductor energy band theory perspective.