REFRACTORY GOLD-BEARING ORES - A REVIEW OF TREATMENT METHODS AND RECENT ADVANCES IN BIOTECHNOLOGICAL TECHNIQUES

The problem of the refractory nature of gold-bearing sulphide ores is described and possible pretreatments are reviewed. Among them, bioleaching is an interesting one from an environmental point of view, but up to the present the process has been too slow The IBES (Indirect Bioleaching with Effect Separation) process improves the kinetics of the bioleaching by means of a physical separation of the chemical and biological effects involved in what we call the indirect contact mechanism. This permits the enhancement of each stage. This process, which has been developed for the treatment of high-grade sulphide flotation concentrates, is proposed for the pretreatment of gold-bearing sulphide ores.