| 摘要 |
<p>PURPOSE:To recover valuable metals such as zinc- or silver-contained in dust by inexpensively applying wet treatment to the dust in good efficiency, by removing the greater part of zinc by exuding the dust with a sulfuric acid solution while subjecting the residue to chlorination roasting in the presence of added chlorine or chloride. CONSTITUTION:Dust which is high in the grade of a valuable metals such as zinc, silver or the like but low in the grade of lead is subjected to first stage exudation by a sulfuric acid solution with a pH of about 2-4 and the treated dust is subsequently subjected to second stage exudation at a sulfuric acid concn. of about 100-300g/l to exudate the greater part of zinc, chlorine and fluorine while zinc in the exudate is recovered by electrolytic treatment and chlorine or fluorine are treated with an alkali agent to be disposed as NaCl or CaF2. On the other hand, chlorine or chloride such as CaCl2 is added to the exudation residue and the resulting mixture is subjected to chlorination roasting in a neutral or oxidative atmosphere, pref., within an indirect heating type roasting furnace to make it possible to easily recover silver chloride.</p> |
