| 摘要 |
<p>Crude dust containing 40--65 per cent of cadmium in an oxidized state is ground and treated with sulphuric acid and then calcined. The mass is then agitated and leached with water to form an impure cadmium sulphate solution. During this step cadmium sulphide may be added to precipitate metallic impurities of the second group. Sodium chlorate is then added to oxidize the iron present and the solution is boiled and cadmium carbonate added precipitating ferric hydroxide which carries the arsenic with it. If iron is not present in sufficient quantity to carry down the whole of the arsenic, ferrous sulphate may be added. The purified cadmium sulphate solution is electrolyzed for deposition of cadmium, using ferrosilicon anodes and cadmium cathode starting sheets. Specifications 392,374 and 419,508 are referred to.</p> |
