By being at least cost neutral, the cost impact of cyanide soluble copper is eliminated, and the project focus can be on the gold. Depending on reagent costs the net benefit for copper recovery could be positive. Besides the benefit in reduced operating cost, there is potential for an increase in gold/silver recovery, higher throughputs and an upstream positive impact on Reserves (1). These benefits must be assessed on a project by project basis.
THE COST
The capital cost for a ReCYN plant is not very different from that of a conventional detox plant using INCO or Caro's acid. The difference is the ReCYN plant has a nett operating cost-benefit, not a nett cost. Cyanide is recycled at 50% of the cost of new cyanide, and there is a further cost benefit from WAD cyanide metals. The benefit of zero detox cost means that even for brownfield projects the plant often has a payback of fewer than 12 months.
PROJECT EXAMPLES
GreenGold is presently involved in three projects that are incorporating ReCYN technology to solve the cyanide copper problem. Each project is very different in size and application, which demonstrates the wider appeal of the technology.
The Martabe Gold Project, Sumatra, Indonesia.
Agincourts’ Martabe Gold Project has been operating for six years and is a large, long life gold/silver project, producing 300koz/a Au. It has a nuisance copper problem, which will increase its impact with deeper ores. Care is exercised in separating high copper material on the ROM stockpile to prevent process upsets in the plant. The problem ore is bled into the plant to prevent any dramatic impact on cyanide consumption and to avoid overloading the detox circuit. In 2018, Martabe undertook a detailed assessment of the ReCYN process to replace their Detox circuit which had become a bottleneck and sensitive to CNsolCu levels. What became evident was the magnitude of the benefit that is realised by incorporating the ReCYN Process. Whittle Consulting undertook a detailed Reserve optimisation study in 2018 (1) and demonstrated the extent of the economic impact ReCYN Technology would have on the project. The following graph illustrates the cumulative benefit from each area of influence.
Note the diverse areas that are impacted by the process, ranging from detox savings through to the Reserve estimate.
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