China Nonferrous Metallurgy

One of the main reasons for the difficulty in treating complex gold ores is the presence of fine gold particles encapsulated within pyrite, which prevents the gold from being leached out. Traditional cyanidation methods cannot effectively break down pyrite, leading to inefficient utilization of gold resources. To improve the gold leaching rate of complex gold ores, this study conducted pre-oxidation treatment experiments based on the excellent oxidation performance of persulfates and the cavitation effect of ultrasound. The effects of process parameters on the oxidation and leaching of gold ores were investigated, and the pre-oxidation mechanism was analyzed in conjunction with characterization results, leading to the following main conclusions. The optimal conditions for oxidative pretreatment were an ultrasonic power of 480W, a sodium persulfate concentration of 180g/L, a liquid-to-solid ratio of 5∶1, a stirring rate of 600r/min, pH=2, and a pretreatment time of 3 hours. Under these conditions, the gold leaching rate could reach 86.97%. With the activation of ultrasound, persulfates can release a large number of ·OH and SO·-4 radicals, which are key to the effective oxidation of sulfides in complex gold ores. Additionally, the cavitation effect of ultrasound can effectively open up the encapsulation of gold by pyrite, increase the specific surface area of the reactant particles, and change the microstructure of complex gold ores, thereby significantly improving the gold leaching rate. This technology increases the gold leaching rate from 49.12% to 86.97%, with significant effects, and is of great importance for the efficient utilization of complex gold ores in China and the expansion of the application field of ultrasound.