| 摘要 |
<p>Zinc is produced from zinc concentrates containing arsenic by smelting in a blast furnace, conducting the vapours produced which contain Zn and As to a condenser, where they are shock chilled by a circulating stream of molten lead to condense the zinc vapour, and cooling the lead, e.g. to 450 DEG C., by passing along cooled launders into a settler to separate out the zinc, the surface of the settler being preferably covered with a molten ZnCl2 flux, the arsenic being removed by adding aluminium to the circulating lead, e.g. either before it enters the condenser or in the sump of a pump circulating lead from condenser to settler, so as to precipitate the lead insoluble compound AlAs. Any iron present with the zinc vapour may be removed as lead insoluble AlFe by adding aluminium in excess of that required to remove arsenic; excess aluminium remaining is preferably removed by reaction with the ZnCl2 flux. Any arsenic remaining in the zinc after treatment with aluminium may be removed by treatment with sodium. The aluminium may be added as an Al-Zn alloy containing not more than 20% Al and melting below 500 DEG C., scrap Al-Zn die-casting alloy containing 4% Al, Al-Si alloy, or a mixture of above with scrap aluminium. Specifications 735,043 and 800,586 are referred to.</p> |
