Work-lead obtd. from sulphate residues - leached with chloride soln., then lead oxychloroide is pptd. and roasted with redn. agent

摘要

Process for mfg. crude-lead or work-lead, starting from residual products, intermediate products and ores, esp. residues contg. lead sulphate, using leaching pptn., and pyrometallurgical treatment of the ppte. The matl. contg. Pb or its sulphate is leached in a conventional manner using solns. contg. chlorides to form soluble chlorine complexes of Pb, then adding milk of lime to ppte. lead oxychloride, the ppte., contg. gypsym, is subjected to melting and redn. at above 800 degrees C., pref. at 900 degrees C. with the addn. to lime, carbon and iron; the work-lead is drawn off and the calcium chloride slag is recycled in the leaching stage, whereas the iron sulphate formed is discarded. The method is used e.g. for treatment of fly-ash arising from the roasting of pyrities, etc., where the Pb is pptd. by adding Ca(OH)2 to from oxychloride of formula ca. 3Pb(OH)2.PbCl2. If the starting matl, contains silver, after pptn. of the lead oxychloride, Ag2S can be ppted. by adding e.g. Na2S so the Ag2S joins the oxychloride and Ag is then obtd. with the Pb, i.e. the work-lead or base-bullion.