Friday, 13 July 2012

Hydro-Pyro Integration in the Processing of Nickel Laterites

Hydrometallurgical process routes are seen to be the future for the treatment of the lower grade nickel laterite ores. Hydrometallurgical projects of recent years have focused on HPAL and have been largely unsuccessful economically, with huge capital cost overruns. The simplest and least capital intensive of the possible alternatives to HPAL is atmospheric heap leaching; development work is also underway by several companies into atmospheric tank leaching which is also a potentially viable alternative. The natural product for a leaching process is a high grade nickel intermediate either from a direct precipitation process (containing approx. 36% Ni) or via Ion Exchange (>50% Ni).

There are many existing pyrometallurgical facilities which could easily be adapted to take this nickel intermediate giving them significant potential benefits especially as raw ore grades diminish. The nickel production from these plants could also be increased and for new plants large capital and operating cost savings achieved. There are also potential environmental benefits with much less energy consumed and lower greenhouse gases emitted per tonne of nickel produced.

In the future an integrated hydrometallurgical plant with attached existing smelter or a more advanced pyrometallurgical smelting process (e.g. a DC Arc Furnace) could well be the way forward for new projects, and this will be the subject of the keynote lecture at Nickel Processing ’12 in Cape Town in November. This will be given by Anne Oxley of Alyssum Ventures Ltd, UK) and Nic Barcza, Metallurgical Engineering Consultant, South Africa, but it would be good to hear the views of others on the future of nickel laterite processing.

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