Lead Smelting and Refining at Kosaka Smelter

Kosaka Smelting and Refining Co., Ltd. operates lead smelting to produce electrolytic lead and to recover precious metals and bismuth with mainly secondary materials from copper smelter and zinc refinery.The lead-bearing residue from zinc refinery is filtered and is dried with the leached residue from copper smelting flue dust. Then these are fed to an electric furnace with some reductant and other lead secondaries to produce lead bullion. The electro-refining of lead is based on Betts process. And we produce crude silver and bismuth metal from anode slime.According to a change of raw materials for the zinc refinery, the residue from that plant changed to high impurity contents. This raw material change becomes a very big problem for the lead smelting in Kosaka and we are doing various improvement.It is very important for lead smelting not to play rolls as the attached process of copper smelter, the zinc refinery and as the production plant of variable metal.Therefore, we are going to introduce a new technology to recover the some metals that we recognized as impurities.The recent lead operation and some experiments for lead smelting in Kosaka are described in this paper.