Sustainable processing of gold cyanide tailings: Reduction roasting, mechanical activation, non-cyanide leaching, and magnetic separation

Abstract

Cyanide Tailings (CTs) are known as hazardous resources that accumulate hundreds of millions of tons, threatening the ecological environment. This work proposes an eco-friendly and efficient way to recover gold, iron, and silicon from CTs. By controlling the reduction atmosphere and temperature in the reduction roasting process, >99% of cyanide could be selectively removed, and 65.3% of the encapsulated gold in iron oxide and sulfide could also be released. The reduction of particle size by mechanical activation liberated 92.3% of gold encapsulated in silicate and iron oxide minerals which increased the extraction efficiency of gold in non-cyanide leaching process to 94.5%. The grade and recovery of iron concentrate obtained from the magnetic separation reached 60.9% and 74.6%, respectively, by regulating the magnetic field intensity of 70 kA/m. While the iron concentrate could be directly traded, the tailings of Si grade 28.4% (w/w) could be used in building materials. The proposed technology can realize the harmless resource utilization of the hazardous CTs with the potential for promising industrial applications.