Abstract:Gypsum slag, as an important by-product of copper smelting system, is a hazardous waste with high disposal cost and high stacking pressure. The calcium oxide obtained from high-temperature calcination and decomposition of gypsum slag has great application prospects in industry. It can be used as a solvent back to the side blowing smelting furnace, which can improve the slag type on the one hand and save the purchase cost of calcium oxide on the other hand. The effects of decomposition temperature, anthracite addition and decomposition time on the thermal decomposition of gypsum slag are discussed by high temperature calcination in reducing atmosphere. The experimental results show that gypsum slag is basically completely decomposed under reducing atmosphere at 1300 ℃ and constant temperature for 60min.