Recovery of zinc from steelmaking dust by the iron-reduction distillation process. Fundamental studies of zinc extraction by the iron-reduction distillation process (3rd report)

On the first reduction stage with a CO₂/CO gas ratio of 0.1 at temperatures 973 and 1073 K, reduction rates were investigated. Iron oxide was preferentially reduced by CO at the lower temperatures. Some zinc in the dust evaporated at an early stage of reaction. This phenomenon was caused by chlorine in the dust. In the second reduction stage at the higher temperature, zinc oxide was easily reduced by the metallic iron in a vacuum of 1 Pa. All zinc was distilled within 20 minutes at 1373 K. Zinc recovery of 89-97% was attained and the iron content in the residues were more than 70%. All cadmium and part of the lead were vaporized in the form of chloride and metal during the first reduction. Most of the lead was vaporized and copper was concentrated in the metallic iron during the second reduction.