Toward Gold Recovery from Refractory Primary Ore by Cyanide-Free Direct Smelting with Copper Sulfide Concentrate

Refractory gold ores containing arsenic are difficult to process using conventional beneficiation and cyanide-leaching technologies. They often have a relatively low content of silicon dioxide (no more than 60%) and also contain arsenic. Therefore, they are difficult to use as fluxes in pyrometallurgical production and require separate processing. A technology based on the reduction pyrometallurgical selection process (RPS process) involves direct smelting. The feasibility of direct smelting of highly refractory primary gold ore with the addition of 5–10% sulfide copper concentrates was investigated. Smelting was conducted at temperatures of 1350–1400 °C under a reducing atmosphere. The resulting matte contained up to 100 g/t gold, while the slags produced contained less than 0.1 g/t gold. Gold recovery into the matte exceeded 98%. The gas purification scheme helps to prevent the release of sulfur dioxide and arsenic into the environment. The obtained matte can be processed at copper smelting plants in either solid or liquid form, with copper and noble metals recovered via the standard processing route: converting → fire refining → electrolytic refining → processing of copper electrolytic slimes for noble metal recovery.