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

Life Sciences

SGS developed the thiosulfate 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 thiosulfate 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.

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

  • Thiosulfate 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 thiosulfate 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. Thiosulfate leaching is particularly well suited to state-of-the-art resin-in-pulp (RIP) gold recovery technologies 
  • Thiosulfate 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 thiosulfate leaching process (ammonium thiosulfate 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 favorable

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 thiosulfate leaching, or one of our cyanide leaching technologies, will give you the highest gold yields possible, while meeting regulatory requirements.