Gold extraction from Carlin-type concentrate by a novel environmentally friendly lixiviant

Recently, cyanide leaching has been progressively inhibited by environmental pollution and long processes. In this study, the effect of leaching conditions on the extraction of gold was investigated with the new environmentally friendly gold lixiviant Jinchan (JC) as a substitute for cyanide. The extraction of gold is 90.8% under the optimum parameters as the liquid-solid ratio of 3:1, the concentration of lixiviant JC of 1.0 g/L, the dosage of activated carbon of 45 g/L, the stirring rate of 300 rpm, the temperature of 50 degrees C, and the reaction time of 5 h. Comprehensive analysis of the gold concentrate and the leach residue was conducted, which revealed that the distribution of exposed gold decreased the most from 75.9% to 18.3%, while other phases of gold had a low extraction caused by the encapsulation. Pretreatment by ultrasound or ultrafine grinding was adopted to liberate the encapsulated gold, and the extractions of gold increased to 91.8% and 96.9%, respectively. Finally, cyclic leaching experiments were carried out, which demonstrated that cycles of activated carbon and leachate hardly influence the extraction of gold within a certain range. Overall, this study suggests that JC has potential for industrial promotion as substitutes for cyanide and provides references for the application of JC.

Automated summary

In this study, the environmentally friendly gold lixiviant Jinchan (JC) was investigated as a substitute for cyanide in the leaching process. The extraction of gold reached 90.8% under the optimal leaching conditions. Analysis of the gold concentrate and leach residue revealed a decrease in exposed gold and a low extraction of other phases due to encapsulation. Pretreatment with ultrasound or ultrafine grinding increased the extraction of gold.