The fine dross is milled by mutual abrasion without the aid of fragmentation devices so the dross breaks up into particles of Zn and particles of ZnO. The Zn and ZnO are then sepd. by using their different densities. Pref. the dross is briefly heated in a protective gas before milling so that the metallic particles melt on their surfaces. The dross may be milled as a suspension in a liq., the ZnO being removed with the liq. Alternatively, the grains of dross may be milled by mutual abrasion in a jet of air. Gives increased recovery of Zn which can be returned to the bath of molten zinc.
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