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

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.

Automated summary

This study proposes an eco-friendly and efficient method to recover gold, iron, and silicon from cyanide tailings (CTs). By controlling the reduction atmosphere and temperature, >99% of cyanide can be selectively removed, along with 65.3% of encapsulated gold in iron oxide and sulfide. Mechanical activation reduces particle size and liberates 92.3% of gold encapsulated in silicate and iron oxide minerals, increasing the extraction efficiency of gold to 94.5% in a non-cyanide leaching process. Magnetic separation results in 60.9% grade and 74.6% recovery of iron concentrate, while the tailings with 28.4% Si grade can be used in building materials. This technology enables the harmless utilization of hazardous CTs and shows potential for industrial applications.