Copper Smelting

—This is a long and elaborate proce effected in reverberatory furnaces or converters. The pyrites ores are roasted to liberate arsenic, and the temperature is then raised until the metal fuses, producing cuprous sulphide and silcate of tron; this silicate 1s removed as slag. By repeating the roasting and fusion, all the iron is removed. (The cuprous sulphide is carefully roasted until it consists of two-thirds oxide, the temperature is then raised until it becomes copper and sulphur dioxide.) On remelting, the copper is poled with green wood, to reduce the oxide remaining. Much copper is refined by electrolysis; the blister copper is cast into slabs for anodes, which decompose under the action of an electric current of low voltage and small amperage. The electrolyte is a solution of sulphate of copper, and the pure copper is deposited on a thin cathode plate of pure metal.