Abstract:
The key of the BIOX process is the exploitation of a naturally occurring mixed bacterial population consisting
of: Acidithiobacillus ferooxidans, Acidithiobacillus thiooxidans (oxidises sulphur compounds only) and Leptospirillum
ferooxidans (oxidizes iron substrates only). These bacteria are able to oxidize gold-bearing sulphide ores and concentrates
under controlled conditions. Thus, they offer an alternative to conventional roasting or pressure techniques developed in
hydrometallurgy in order to recovery Au and Ag from refractory sulphide gold ores and concentrates. Using the BIOX
process as a pretreatment procedure of refractory sulphide gold ores and concentrates, Au and Ag recovery yields after
cyanidation increased up to 78 % for Au and to 83 % for Ag.
