Role of microorganisms in winning metals from low-grade ores

Abstract

Use of bacteria in various industrial processes is known for a very long time. Fermentation is an old art and has been used recently in the production of organic chemicals. Micro-organisms are employed in modern sewage plant. Geological studies have indicated that microorganisms influenced the formation of some ores notably bog iron and manganese type deposits. Biogeochemistry refers to studies on the part played by living microorganisms in the deposition of sediments and the formation of minerals. The fact that some bacteria will attack minerals is not new. Dump and heap leaching operations for the recovery of copper from low grade ores is being practised for several decades now. The copper which appears in the leaching water along with iron and sulphuric acid was a long time thought to have been produced by the action of sulphuric acid on the copper minerals and the sulphuric acid was considered as a product of the atmospheric oxidation of the sulphuritic materials. The fact that there could be a bacterial oxidation of the sulphides was realised in early 1950's and Bryner et al in 1954 confirmed that the release water of Bingham Canyon is largely due to the action of micro-organisms on sulphide minerals. This micro-organism has since been found to be involved in the leaching operations in Arizona, British Columbia, England, Russia and Congo. The Mine Canerea Sonara Mexico and from the mountain copper company mine in Redding, California.