The result of this precipitation is a cement cake with a lead content of about 70 percent. Lead refineries can process the cake to recover lead and other metals. The zinc-depleted solution recirculates to the leaching process. Electrolyte purges the accumulated alkaline metals to an evaporator that separates salts by concentration and crystallization. Process-water balance is maintained, and waste heat can be used if it's available.
Companies sell the alkali chlorides to aluminum recyclers.
Dry EAF dust, mill-scale fines, and coke fines are blended, pelletized, and placed on the hearth of the RHF, where they are metallized and carburized. Dust collected from the baghouse is mixed with carbon fines and fed to the plasma furnace, where the zinc oxide is reduced rapidly. Then the zinc metal is volatized. The CO-rich gas stream is fed back to the RHF and combusted. The molten lead and zinc are tapped separately and cast into sows, or pigs, for resale.