THE RECYN PROCESS - CHANGING THE NEGATIVE PERCEPTION OF CYANIDE By Malcolm Roy Paterson
PT Green Gold Engineering, Indonesia Presenter and Corresponding Author Malcolm Paterson malcolm@greengoldengineering.com
ABSTRACT Cyanide is firmly established in the gold mining industry as the overwhelming choice of solvent for gold and silver recovery from ores. Several niche applications for alternative reagents have been proposed, but it’s unlikely the superiority of cyanide will be seriously challenged for some time. The reason alternative solvents are widely sought is due mainly to the negative connotations of cyanide in the public arena; and its poor reputation has been further harmed by several catastrophic tailings dam failures in recent years. This paper describes a development that can help change the negative perception of cyanide in gold plant processing and, at the same time, substantially improve the economics of its use. Known as the RECYN Process, it is a resin based technology that allows for the economic recovery of cyanide from gold/silver plant tailings. The process is also used to recover dissolved base metals and gold/silver cyanide complexes. The combination of recovery steps overcomes any need for further detoxification of the tailings, changing a nett cost to a positive return. Gold projects incorporating the RECYN Process can reduce the purchase and shipment of cyanide by 50%, reduce the overall cost of cyanide usage, and produce a fully decontaminated tailings stream from the process plant. These advantages, both economic and environmental, can help change the negativity associated with cyanide. The Mirah Gold Project in Central Kalimantan, Indonesia has, for over two years, successfully operated a commercial scale plant (1Mtpa ore) for the recovery and recycle of cyanide on a continuous basis. An average of 1t/day of NaCN has been recycled at a cost of 50% of new cyanide, with no further detoxification of the tailings required to meet environmental compliance levels. A second project is presently under construction, designed to recycle 1.5t/day NaCN, incorporating many improvements in operation and efficiency acquired from the first project. We believe the RECYN process is now sufficiently robust for wider international commercialisation and will become a standard part of the gold process plant flow sheet.
Keywords: Cyanide, carbon, tailings, resin, detoxify, recovery, environmental.
ALTA 2017 Gold-PM Proceedings
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