| 摘要 |
<p>A process for the extraction of precious metals from ashes and industrial residues containing them comprises charging an intimate mixture of the said material with scorifying substances (having a reducing or an oxidizing action as required) and a lead compound on to the surface of a previously prepared molten slag, the process being characterized by the use of electrical self-resistance heating for bringing the slag to the required temperature and maintaining it at that temperature. The raw materials used may be goldsmith's ashes or sludges from the electrolysis of copper or from the production of copper sulphate. The lead compound may be litharge, lead carbonate or lead hydroxide. In an example the charge contained 100 parts by weight of goldsmith's ashes, 60 parts of cupel sole, 50 parts of glass and 100 parts of litharge the reaction being carried out at about 1200 DEG C. Metallic lead containing precious metals is formed and sinks below the slag. Specification 652,776, [Group XI], is referred to.</p> |
