ACIDOPHILIC BACTERIA - THEIR POTENTIAL MINING AND ENVIRONMENTAL APPLICATIONS

The increasing acceptance of biological processes for the treatment of refractory gold-bearing concentrates should be considered as a positi ve move both in terms of process flowsheet development and its commitm ent to the environment. Research and development is now focusing on th e application of moderately thermophilic and extremely thermophilic ac idophiles in the treatment of both refractory gold-bearing and base-me tal mineral sulphide concentrates. Current literature on the applicati on of biological processes is still dominated by studies of mesophilic bacteria such as Thiobacillus ferrooxidans and Leptospirillum ferroox idans although literature is becoming more prevalent with respect to t he higher temperature acidophiles. This current experimental study hig hlights the problems of arsenic toxicity to certain strains of moderat ely thermophilic bacteria when oxidising both refractory gold and base -metal sulphide concentrates, It also concludes that these bacterial s trains were capable of readily oxidising a chalcopyrite/pyrite concent rate (typical of base-metal sulphide concentrates). A mini literature review discusses some of the current and potential applications of aci dophilic bacteria both within the minerals industry and in allied disc iplines including treatment of metalliferous mine wastes, acid mine wa ters and sulphurous flue gases. Conclusions are drawn for both the exp erimental work presented and the literature reviewed.