Advanced Materials Research Vols. 20-21

Abstract: My perceptions of the biohydrometallurgical field span four decades and stem from being a professional microbiologist conducting academic research and research for process development and applications. My experiences have given me an appreciation for knowledge gained through fundamental research and the transfer of this knowledge to development of commercial scale applications of microbial processes. The symposia series for international activities in biohydrometallurgy has been a major factor in advancing knowledge and applications for microbial bioleach systems. The first international biohydrometallurgy meeting was held in Braunschweig, Germany in 1977. This was the predecessor for the International Biohydrometallurgy Symposia. As evident from the Symposia, advances in development and applications of biohydrometallurgy technologies follow an evolutionary, rather than revolutionary progression from demonstration of knowledge at the laboratory scale to engineering commercial plants.

Abstract: Los Bronces has two ROM dump leach operations called Leach I and Leach II. Leach I was commissioned in 1998 and currently produces 12,700 ton per year. The copper mineralization in these dumps is largely sulfides, namely 60% chalcocite/covellite, 30% chalcopyrite and the balance is oxides. The Leach II plant, commissioned in early 2002, was built to treat around 700 million ton of marginal ore having 0.45% total copper. The copper mineralogy of this material is estimated to be 70% chalcopyrite, 20% chalcocite/covellite and the balance oxides. Current copper production is 33,700 ton per year. Early in 2004 it was decided to conduct a complete column test work program, aimed at reducing power, acid and lime consumption at the Leach II plant. The results of this work, partially reported at IBS 2005, have been successfully applied to the commercial operation since the end of 2005. As a consequence, the projected reduction in operating costs for 2006 of US$ 5.5 million was accomplished. The main results of the column test work program, the modifications implemented together with the results obtained at the operation, including a molecular characterization of the microbial population, are discussed in this paper.

Abstract: Trial tests on biotechnology of flotation tailings processing from copper-concentrating factory at Almalyk Mining and Metallurgical Complex are carried out. Suitability of flotation tailings to processing by a method of heap bacterial leaching is experimentally determined. It is shown, that extraction of copper from flotation tailings makes 56 %, biooxidation of chalcopyrite makes more than 62 %, and pyrite - 87-92 %.

Abstract: Talvivaara complex multi-metal black schist deposit in Sotkamo, Finland, is the largest known sulfide nickel deposit in Europe with 340 million ton of classified resources. The mine can be operated for a minimum of 25 years with an annual nickel output of over 30 000 ton, which is about 2,5 % of the global production of primary nickel. Significant amounts of zinc, copper and cobalt can also be produced. In summer 2005, a 50 000 ton demonstration plant was constructed to the mine site. A representative ore sample was mined, crushed to 80 % -8 mm, agglomerated and built to a two-part heap (8 m high, 50m times 80 m). Irrigation of the heap was started in August 2005. The pilot heap was inoculated with indigenous bacteria collected from the site. The amount of bacteria in the pregnant leaching solution has been in the range of 106 – 108 cells/ml. The bacteria involved are mesophilic and thermophilic ones. The start-up of the solution flow resulted soon in elevated temperatures of over 50 0C in the pregnant leaching solution. The rise is due to the oxidation of the large quantity of pyrrhotite and pyrite in the ore. The elevated temperatures have also been maintained over the boreal winter conditions. Metal recovery was started in November 2005. At the end of the year 2006 94 % of Ni, 83 % of Zn, 3 % of Cu and 14 % of Co have been recovered. The demonstration plant is still running. The study has proven that Talvivaara black schist ore is well suited for bioheapleaching. Building of the mine will start in spring 2007, bioheapleaching in summer 2008 and the metal recovery plant in autumn 2008, if everything proceeds according to the plans.