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MEI Online: Biotechnology: Latest News: December 29th 2004


Click for more info on Biomining '21


:: Talvivaara to Test Cold Bio-heap-leaching

Pilot-scale bio-heap-leaching (BHL] is planned next year at theTalvivaara polymetallic sulphide deposit in the Sotkamo district of central Finland, to test whether the process is effective in sub-Arctic climatic conditions.

If successful, Finland could have a 'substantial new source of nickel, zinc and copper. The work is being carried out by Talvivaara Projekti Oy (TPO).

TPO's chief executive, Pekka Pera, is a mining engineer and formerly worked for Outokumpu. He is being advised by Jaakko Puhakka, an expert on bio-leaching at the University of Tampere. The extent of previous exploration has been sufficient to outline, to JORC standards, a measured and indicated resource of 280 Mt averaging 0.27% Ni, 0.14% Cu, 0.024% Co, 0.55% Zn, 10.9%Fe, 9.1%S and 7.5% C,within a total resource of 320 Mt.

Professor Puhakka is convinced that the two deposits, Kuusilampi (206 Mt) and Kolmisoppi (112 Mt), can be successfully and profitably exploited using BHL. A major pilot-scale test involving a 25,000 t bulk sample will be carried out on site during 2005, designed to confirm successful bench-scale tests, which, on 50 kg samples ground to 8-12 mm, indicate 90% recovery for nickel and zinc, and 60% for copper and cobalt over a 550-day leaching period.

The project could take two to three years to get to the bankable feasibility study stage. An environmental permit could be secured in 2006, mine construction beginning towards the end of that year and a possible production start early in 2009.

The advantages of successful BHL is that very low-grade material can be treated, hence the resources at Talvivaara are considered by TPO to be virtually reserves. An annual production level of 30,000 t of nickel, 60,000 t of zinc and 10,000 t of copper is envisaged over at least 20 years, with operating costs of under US$ l.60/lb. Most of the nickel sulphide is pyrrhotite and the leaching process is exothermic.


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