| 摘要 |
Gold and/or silver adsorbed on an anion exchange substance as the corresponding cyanide are eluted by means of an organic solvent, such as methanol, ethanol or ethyl acetate, containing a minor proportion of an inorganic acid, preferably hydrochloric acid, and the resulting solution is distilled to remove substantially all the solvent, the precipitated gold and/or silver being separated from the residual acid e.g. by filtering through a filter press or candle filter. Distillation is preferably carried out in such manner that the temperature at a point a short distance below that at which condensation commences in the condenser is approximately 1 DEG C. above the boiling point of the solvent until distillation is substantially complete. The operation may be carried on continuously or semi-continuously, the solution being pumped to a constant head tank from which is flows to the distillation vessel under gravity or under pressure. Specification 727,582 [Group III] is referred to. |
