Biomining is a biotechnological process carried out in many parts of the world that exploits acid loving microorganisms to extract metals from sulphide minerals. One industrial biomining method is called ‘heap bioleaching’ where typically copper containing minerals are piled into very large heaps, acid and microorganisms are added to the top and the soluble metal is collected at the heap base.
The role of the different types of microbes in the process is to speed up metal solubilisation by oxidising ferrous iron to ferric and removing sulphur compounds that can accumulate on the mineral surface. Metals are most efficiently released from sulphide ores if the microorganisms form a thin layer, termed a ‘biofilm’, on the mineral surface and a crucial stage in bioleaching is how efficiently the microbes attach to the mineral.
This project will test how rapidly a biofilm is formed and copper is released from the mineral by different combinations of microorganisms and the order that they are added. Data on the biological processes the microorganisms carry out will be used in computer modelling to suggest the best combination and order in which to add the different types of microbes. This in turn will increase the efficiency of industrial bioleaching by reducing the time between when a heap is built and when the first metals are collected.