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Thiosulphate leaching is a process that recovers gold from ore without the use of cyanide.

SGS developed the thiosulphate leaching process because in some jurisdictions, increased regulation pressure means that cyanide cannot be used or transported.

We are a global technical leader in the field of thiosulphate leaching. Our laboratory and industry experts have spent years designing and developing the technique into a viable alternative to cyanide for some gold-bearing ores.

Thiosulphate leaching offers a number of benefits related to gold recovery yields and environmental concerns:

  • Thiosulphate leaching of gold ores has great potential to reduce the impact on the environment. Unlike cyanide, which is highly toxic, the chemicals used in the thiosulphate leaching process are benign. This technology offers great potential in those jurisdictions where the use of cyanide is banned outright, or is subject to intense negative publicity for environmental reasons
  • This process results in recoveries that are close to those generated by cyanide leaching in many cases. In recovery operations that are affected by “preg-robbing” ores, it can yield substantially better recovery than cyanide. Thiosulphate leaching is particularly well suited to state-of-the-art resin-in-pulp (RIP) gold recovery technologies 
  • Thiosulphate leaching is an alkaline process (usually operated in the pH 8 to 10 range) so there are no concerns with corrosion of equipment in the recovery operation
  • The main chemical components of the thiosulphate leaching process (ammonium thiosulphate and ammonium sulphate) are common fertilizers. This opens up the additional possibility of using mine tailings solutions in agricultural applications, in regions where environmental regulations are favourable

Contact SGS early in your planning and process development stages to discuss your timing, project scope, environmental concerns and financial requirements. Our technical experts will establish whether thiosulphate leaching, or one of our cyanide leaching technologies, will give you the highest gold yields possible, while meeting regulatory requirements.