Application of Acidithiobacillus ferrooxidans VKM B-3655 for bioleaching silicate ore

Abstract

Acid metal bioleaching is common and classical for nickel recovery from the sulfide refractory ores: various microorganisms can oxidize sulfides as energetic substrates. Silicate nickel ores are widespread in the world but their bioleaching is more problematic because silicates cannot serve as energetic substrates. Meanwhile iron in the silicate nickel ores presents a significant part and can be used by some acidophilic autotrophic microorganisms for the ore destruction. In model experiments, we studied application of acidophilic autotrophic sulfur-/ iron-oxidizing bacteria Acidithiobacillus ferrooxidans VKM B-3655 for the nickel recovery from the nickel-bearing silicate ore with high content of iron. The strain was selected by its ability of iron oxidation and resistance to arsenic which also presented in the ore. We also evaluated possibility to stimulate the bioleaching with formate as additional energetic substrates or with persulfate for increasing the medium redox. It was shown that low concentrations of sodium formate (0.3%) and persulfate (0.1%) stimulated growth of A. ferrooxidans while higher persulfate concentration (1.0%) stimulated the ore bioleaching.