Smelting is one of the casting production processes. The pyrometallurgical process in which metal materials and other auxiliary materials are put into the heating furnace for melting and quenching and tempering, and certain physical and chemical changes occur in the materials in the furnace at high temperature (1300 ~ 1600K), so as to produce crude metal or metal enrichment and slag. In addition to concentrate, calcine, sinter, etc., sometimes it is necessary to add flux to make the charge easy to melt and reductant for some reaction. In addition, in order to provide the necessary temperature, it is often necessary to add fuel for combustion and send air or oxygen enriched air. The crude metal or metal concentrate can be separated due to the small mutual solubility with the molten slag and the density difference into two layers. The concentrates include matte and yellow slag, which must be treated by converting or other methods to obtain metal.