16 Dec RECYN – A New Future for Cyanide in Mining

Cyanide is firmly established in the gold industry as the overwhelming choice of solvent for gold and silver recovery from ores. Several niche applications for alternatives have been proposed, but it is unlikely the superiority of cyanide will be seriously challenged for some time.

The reason alternative solvents are widely sought is simply due to the negative connotations of cyanide in the public arena. The historical basis of the poor reputation is not helped by several catastrophic tailings dam failures in recent years.

This paper describes a process that can help change the negative perception associated with the use of cyanide 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 to further detoxify the tailings, changing a net cost to a profit. Gold projects incorporating the RECYN Process can reduce the purchase and shipment of cyanide by 50%, reduce the cost of cyanide usage and produce a fully decontaminated tailings from the process plant. These advantages, both economic and environmental, can help change the negativity associated with cyanide.

The core technology is not new, having been first published in South Africa in the 1950’s by Eric Goldblatt. It was reinvented in the late 80’s by a Canadian group called Tallon, and known as the Vitrokele Process. Several commercial operations based on gold recovery were constructed with varying success, until a combination of circumstances occurred in the mid 90’s to once again put the technology into hibernation.

Over the last twenty years there have been several attempts to duplicate the process with small modifications, but nothing commercial has resulted. Green Gold (GG) has successfully operated a commercial scale plant for the recovery and recycle of cyanide on a continuous basis for over two years. An average of 1t/day of NaCN has been recycled at a cost of 50% of new cyanide. There has been no further detoxification of the tailings to meet environmental compliance levels. A second project has been operating for 4 months recycling 1.5t/day.