Development of the New Zinc-Separation Process for the Blast Furnace Dust

Blast furnace dust has been recycled as iron source in the sintering process. However, dust-recycling rate is limited due to the zinc content; therefore, it is necessary to remove zinc from the dust. In this study, laboratory-scale experiments were conducted. The hydrometallurgical process is composed of acid leaching, leachate purification, and zinc recovery. By acid leaching, 68 wt% of zinc and 6.4 wt% of iron were selectively leached under the pH value of 2.0. By the addition of hydrogen peroxide, the iron was completely separated from leachate under the pH value of 5.0. Zinc was finally recovered as zinc hydroxide at alkali condition (pH value of 9.0). The zinc concentration in the sludge was 42.6 wt%. Based on the experimental results, the blast furnace dust can be potentially used as zinc and iron source.