Abstract:
In an altered rock-type gold-bearing polymetallic ore from Qinghai Province, lead and zinc minerals are predominantly sulfides with coarse grain size, making them relatively easy to recover by beneficiation. Gold minerals mainly consist of silver-bearing native gold, electrum, and a small amount of kustelite with fine particle size. Part of gold minerals is closely associated with metallic minerals such as galena, sphalerite, and pyrite, as well as gangue minerals, leading to difficult liberation. Based on the process mineralogy study results, comparative experiments were conducted on two process schemes, namely flotation followed by leaching and leaching followed by flotation, to ensure efficient recovery of gold and silver while also achieving comprehensive recovery and utilization of lead, zinc, and sulfur. The results show that the leaching followed by the flotation process outperforms the flotation followed by the leaching process. By using the leaching followed by flotation process, the whole-ore cyanidation leaching achieves a gold leaching rate of 86.31 % and a silver leaching rate of 33.58 %. From the flotation of the leaching residue, a lead concentrate is obtained containing 5.61 g/t Au, 283 g/t Ag, and 59.68 % Pb, with recoveries of 4.08 % for Au, 53.64 % for Ag, and 86.69 % for Pb, as well as a zinc concentrate containing 40.16 % Zn with a zinc recovery of 52.00 % and a sulfur concentrate containing 44.23 % S with a sulfur recovery of 70.36 %. The total gold recovery from whole-ore cyanidation leaching plus the lead concentrate is 90.39 %, and the total silver recovery is 87.22 %. The leaching followed by the flotation process achieves efficient recovery of the precious metals gold and silver while simultaneously producing lead, zinc, and sulfur concentrates that meet grade requirements, thereby maximizing the comprehensive recovery of gold, silver, lead, zinc, and sulfur.