Mechanisms of bioleaching. Basic understanding and possible industrial implications

GIAVENO A.; URBIETA M.S.; DONATI E.R.

BioHydrometallurgical Processes: A practical approach

CETEM - CENTRO DE TECNOLOGIA MINERAL

Lugar: RIO DE JANEIRO; Año: 2011; p. 27 - 37

This chapter summarizes the current understanding of bioleaching mechanisms. It includes a brief description of the model widely accepted for explaining the microbial attack to metal sulphides under aerobic conditions. This model recognizes the metal leaching as a chemical process in which the leaching reactions are carried out by iron(III) and protons species using two different (thiosulphate and polysulphides) mechanisms according to the type of sulphide. Microorganisms are just responsible to regenerate those leaching agents and this role can be done through contact or non-contact ways. Attached cells are much efficient to dissolve sulphides than those in solution. The possible contribution of anaerobic growth to enhance the oxidation of sulphides is also described. As a practical consequence of these mechanisms, biomining processes are carried out by consortia characterized by iron and sulphur oxidzing microorganisms and heterotrophs capable of oxidizing organic compounds. The mechanisms also have some possible industrial implications which are discussed at the end of the chapter