An experimental study of the interaction between Acidithiobacillus ferrooxidans and sulfide ores

Based on experiments of interactions between Acidithiobacillus ferrooxidans(A.f) and sulfide ores,this paper studied the oxidation of different sulfide minerals in the same ore sample mediated by A.f,and analyzed the reacted mineral surfaces and secondary products.The purpose of this study is to disclose the selectivity of A.f mediated oxidation and the dissolution sequence of different sulfide minerals in the same ore sample.Analytical approaches,such as inductively coupled plasma optical emission spectrometer(ICP-OES),scanning electron microscope-energy dispersive spectrometer(SEM-EDS) and X-ray diffraction(XRD),were employed to investigate changes in the concentrations of specific metal ions in the solution,surface morphology of the original minerals and precipitations during the experimental period.The results indicate remarkable difference between the interaction effects of A.f on different sulfides.The effects on both galena and sphalerite are very evident,while those on pyrite are rarely observed.It is concluded that galvanic reactions occur in the bacteria mediated oxidation of sulfide ore due to the contacts of different sulfides with various crystal structures in the ore samples.Pyrite grains,generally acting as the cathode,are protected,which exhibits a selective interaction of A.f with sulfide minerals in ores.The preferably oxidized sequence of these sulfides in an A.f-mediated ore sample is in order of sphalerite,galena and pyrite.