Extraction of valuable components from sulphide ores using microorganisms is a recognized biotechnological method, combining several advantages over traditional methods of mineral processing. This paper presents the main factors affecting the bacterial-chemical leaching and methods of leaching with the participation of microorganisms. Some physical-chemical (temperature, pH, oxygen, carbon dioxide, nutrients, metals and other chemical elements) and microbial (cell count and microflora activity) properties are given, either directly or indirectly (suppressing or contributing to the growth and oxidative capacity of microorganisms) affecting the kinetics of the process. The paper discusses the characteristics of the mineral substrate, including galvanic interaction of sulfide minerals and the formation of passivating layers on the surface of the ore during oxidation, emphasizing the importance of the electrochemical interaction of the components of the leaching system. Bioleaching is a complex process, which is a combination of mainly chemical reactions mediated by the microbial component, therefore, to improve the kinetics, it is necessary to consider, monitor and regulate the listed range of factors.
Bacterial and chemical leaching of metals has established itself as an alternative technology for hydrometallurgical processing and enrichment of ore due to a reduction in capital costs and adverse environmental impact. Various bioleaching processes are successfully used for the processing of sulfide concentrates, poor sulfide and oxidized ores. One of the most important tasks for further development of this branch of biotechnology is the improvement of bioreactor installations (in particular – flow type) and installation of systems of additional control of technological parameters. The article briefly highlights the main results obtained at the GSRC of FEB of RAS within the framework of bioleaching studies of sulfide cobalt-copper-nickel ore. A description of a bioreactor for the study of bioleaching in a batch mode and a cascade type reactor for studying bioleaching in a continuous mode is given. A model of an improved bioreactor for bacterial-chemical leaching of sulfide ore is presented. A detailed description of the microcontroller control method for technological parameters is given. The field of application of the presented results is laboratory, integrated and semi-industrial tests of the technology of tank and reactor bacterial-chemical leaching of sulfide ores.
