Development of a gold leaching reagent as an alternative to cyanide: Synthesis and performance evaluation

Cyanide is the most widely used reagent in gold production processes. However, cyanide is highly toxic and poses safety hazards during transportation and use. Therefore, it is necessary to develop gold leaching reagents that can replace cyanide. This paper introduces a method for synthesizing a gold leaching reagent. Sodium cyanate is used as the main raw material, with sodium hydroxide and sodium ferrocyanide used as additives. The gold leaching reagent can be obtained under the conditions of a mass ratio of sodium cyanate, sodium hydroxide, and sodium ferrocyanide of 15:3:1, synthesis temperature of 600°C, and synthesis time of 1 h. This reagent has a good recovery effect on gold concentrate and gold-containing electronic waste. The gold leaching rate of roasted desulfurized gold concentrate can reach 87.56%. For the extraction experiments of three types of gold-containing electronic waste, the gold leaching rate can reach over 90% after 2 h. Furthermore, the reagent exhibits good selectivity towards gold. Component analysis indicates that the effective component in the reagent could be sodium isocyanate.