Microbial Succession during a Heap Bioleaching Cycle of Low Grade Copper Sulphides. Does this Knowledge Mean a Real Input for Industrial Process Design and Control?

The paper “Bacterial succession in bioheap leaching” [1] initiated the search for methods to analyze the microbial dynamics in bioleaching industrial processes as a key to advancing commercial bioheap applications. “Chemical and physical conditions within bioheaps change radically from the time the bioheap is stacked and inoculated until bioleaching is completed.” The results from a comprehensive monitoring program by culturing and molecular techniques in an industrial bioleaching process for Run-of-mine (ROM) low grade copper sulfide ore in Chile will be summarized. The analysis of the compiled information permits an understanding of changes in microbial substrates availability, chemical and physical conditions. The impact of other aspects on microbiology, such as the mining programme and the industrial design are also considered. The bacterial succession in bioheap leaching solutions allowed the leaching cycle stages to be describe as: i) Acid conditioning and soluble copper releasing, ii) Chalcocite Bacterial leaching (ferrous oxidation); iii) Chalcocite Bacterial leaching (ferrous and reduced sulfur compounds –RSC- oxidation); iv) Bacterial leaching of sulphide minerals with higher rest potentials (pyrite and covellite ), v) Bacterial oxidation of remnant sulfide minerals and RSC.