:: Innoculation of Leach Heaps Research Project

An R&D programme initiated by Mintek will focus on a unique and effective inoculation technology that is aimed at shortening start-up times, leading to faster copper extraction and increased recoveries. This will substantially improve the economic performance of copper sulphide heap-bioleaching operations.

There are currently nine heap-leach operations world-wide processing copper sulphide ores, with an annual production of US$1.3 billion worth of copper metal, and this figure is set to rise to more than US$2 billion within a few years. Heap leaching has a potential cost advantage of at least 10-15 US cents per pound of copper - around 10 per cent of the current copper price - compared with the conventional process.

In sulphide heap leaching, the reaction is catalysed by iron- and sulphur-oxidising bacteria that have to be specifically introduced into the heap. However, with current practice, it is extremely difficult to obtain an adequate bacterial population, and this has resulted in start-up problems and below-optimum performance at most sulphide operations. As a result, the anticipated cost improvements have not been fully realised.

The work will be conducted in partnership with Mineral Energetics, a private South African company that was established in 2002 to develop and commercialise new technologies in the mining and related fields. Mineral Energetics has rights to the patent upon which the proposed technology is based, and Mintek's Biotechnology Division will act as the technology development partner. Both organisations will contribute to the commercialisation of the technology.

The consortium has a separate co-operation agreement with a major international resources company, which will provide a site for field testing the technology.