| 摘要 |
<p>508,142. Recovery of copper; cuprammonium compounds. BRITISH BEMBERG, Ltd. July 12, 1938, No. 20605. Convention date, Sept. 9, 1937. [Classes 1 (ii) and 1 (iii)] Lime-containing copper mud obtained in working up copper-containing waste waters from the cuprammonium artificial silk industry, for example, by precipitating ammoniacal copper-containing spinning water with lime, is treated with ammonia and an alkali metal or ammonium carbonate, and preferably with ammonium salts such as the sulphate or chloride so that the copper is converted into a tetrammine compound, and calcium carbonate is precipitated, carrying down impurities present. The solution is (1) heated, e.g. at 80-85‹ C. until all the ammonia has escaped, the copper separating as basic salt, e.g. carbonate or sulphate, or (ii) heated with addition of caustic soda, the copper depositing as black oxide which may be worked up to any basic salt. The ammonia is led back to the circuit, in process (ii) partly after conversion into the desired ammonium salt. In process (i), ammonium sulphate solution containirig a relatively small amount of copper separated from the basic salt is also introduced into the circulating process. The mud may previously be treated with a deficiency of acid to form a basic salt, for example with the so-called copper acid arising on decoppering freshly produced structures with dilute sulphuric acid,</p> |
