The authors challenge the traditional thinking that whole ore cyanidation followed by Carbon in Pulp (CIP) or Carbon in Leach (CIL) should be applied as a standard process in the majority of gold processing flow sheets. The concept of whole ore leaching by using cyanide can result in unnecessary environmental and capital risk. Alternative, currently available technologies can be used to provide the desired level of gold recovery at a much lower installed cost and less impact on the environment. Gravity concentration, alone or in conjunction with flotation, can produce a gold bearing concentrate that can then be fed directly to a batch or continuous intensive cyanidation unit._x000D_
The In-line Leach Reactor (ILR) is an intensive cyanidation unit developed by Gekko Systems of Australia. Advantages of this technology include significantly reduced capital outlays for greenfield plants or plant upgrades and increased investor returns. Reduction of onsite cyanide and carbon inventories improves plant safety, materials handling and site security. By using direct electrowinning to treat the gold bearing solutions produced by the ILR, the need for a conventional carbon stripping circuit is removed. Potential also exists to increase grind size - saving energy, further reducing capital and operating costs and decreasing the environmental impact of a mill. Detoxification of cyanide before the release of solution to the tailings dam can minimise tailings disposal and containment requirements._x000D_
When used in the right application the proposed process will have little or no impact on gold recovery and may actually increase recovery for complex ores. Areas applicable to this type of treatment include: plants in environmentally sensitive regions, lower tonnage higher grade deposits, coarse gold deposits, and preg robbing ores - some of which may not currently be economically feasible using standard processes and flow sheets. We have provided two examples of such projects, where an alternative to whole ore leach and CIP or CIL has the potential to deliver these benefits._x000D_
FORMAL CITATION:Gray, A, Abols, J, McCallum, A, Patrick, G, Johansen, G and Grigg, N, 2004. CIP - who needs it? A combination circuit of gravity, flotation and intensive leach may provide the optimal environmental and cost outcome for gold plants - stage II - results, in Proceedings New Leaders' 2005, pp 149-156 (The Australasian Institute of Mining and Metallurgy: Melbourne).