Control and optimization in the bio-extraction of metals from primary ores before the new mineral processing techniques

Abstract

The bioleaching is a biochemical process that is based on the capacity that certain microorganisms have to transform insoluble elements present in certain sulphide minerals in soluble elements and easy to be extracted from the lecheate in conventional downstream processes. The leaching microorganisms are characterized by a unique capacity to grow in environments virtually uninhabitable for the majority of microorganisms, as they live in places with extremely low pH and in temperature that can vary between 25 to 80°C. In a process of leaching sulphide minerals it is used to obtain a flotation concentrate so as to recover a large part of the metal of interest bearing sulphide minerals. However, the bioleaching of metal sulphide bearing ores is not an easy task taking into consideration that the metal sulphide minerals are not that available to be oxidized being frequently encapsulated in the gangue minerals, which imposes a barrier to the sulphide minerals oxidizing agent (i.e., Fe3+ ion) and microorganisms to act. With the advent of the HPGR (High pressure grinding rolls) and the electrodynamic fragmentation (SELFRAG), micro-fractures are created, and, in addition, with the possibility of monitoring and controlling the bioleaching parameters (i.e., pH, Eh, ore bed temperature, ionic strength etc.) the bio-extraction of metals, out of sulphide bearing ores, will definitely enhance such process.