Abstract:Mercury flow in copper smelting process of a copper smelting enterprise in Yunnan Province was systematically analyzed by material balance algorithm. The results show that mercury mainly comes from copper concentrate in copper smelting system. Most of mercury enteres into acid mud and waste acid, some enteres into sulfuric acid, and few is charged with smoke during acid making. Mercury in flue gas meets the emission limits. After treated by sewage disposal system, mercury in waste acid enteres into arsenic-calcium slag, neutralization slag and gypsum slag. The return water index was qualified.