Abstract:A gold-and silver-bearing sulfur concentrate in Yunnan has a sulfur grade of 44.24%, gold and silver grades of 3.07g/t and 36.3g/t respectively. Gold mainly exists in the form of bare gold, and silver is mainly in the form of silver sulfide and sulfide-coated silver. After oxidative roasting pretreatment, the leaching rates of gold and silver were 79.66% and 68.13% respectively. At high temperature, iron oxide would appear in a molten state, resulting in secondary encapsulation of gold and silver. Adding the roasting additive CaO, the gold leaching rate increased to 86.56%, and the silver leaching rate increased to 68.43%. The affinity of CaO with Fe2O3 and SiO2 is higher than that of ZnO. During the roasting process, CaO is added to react with ZnO·SiO2, PbO·SiO2 and FeO·SiO2 to form CaO·SiO2, which hinders the formation of dense ZnO·SiO2, PbO·SiO2 and FeO·SiO2 and reduces its for the coating of gold and silver, the calcined silicate-coated gold is reduced from 0.52g/t to 0.13g/t.