PROCESS AND PLANT FOR REMOVING LEAD AND ZINC FROM METALLURGICAL-WORKS DUST.

摘要

PCT No. PCT/EP93/00747 Sec. 371 Date Sep. 26, 1994 Sec. 102(e) Date Sep. 26, 1994 PCT Filed Mar. 26, 1993 PCT Pub. No. WO93/19213 PCT Pub. Date Sep. 30, 1993The foundry dust is fed to a first furnace atmosphere which is preferably at 1000 DEG to 1100 DEG C. With the dust pellet being continuously rolled around, it remains therein until in particular chlorine, alkali and lead compounds have almost completely evaporated out of the dust. Experience has shown this takes an hour. In that operation a scavenging gas flow is fed to the furnace atmosphere whereby the lead-chlorine-alkali vapour produced in the rotary cylindrical furnace is passed out of sane to a condensation and filtering apparatus. Reducing agent, in particular coal, is then introduced into the foundry dust and same is fed to a further furnace atmosphere which in particular is at 1150 DEG to 1350 DEG C., where it is continuously rolled around. In that way the zinc oxide contained in the dust is reduced, the dust remaining in the furnace until zinc has substantially completely evaporated in the form of zinc metal vapour out of the dust into the oxygen-bearing furnace atmosphere and there the zinc metal has changed to zinc oxide. Experience has shown this takes up to two hours. In that operation once again a scavenging gas flow is fed to the furnace atmosphere, to carry the zinc oxide out of the furnace, where the scavenging gas is cooled with the zinc oxide and filtered.