ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Social and Environmental Engineering
Preparation of ZnSO4·7H2O and Separation of Zinc from Blast Furnace Sludge by Leaching-Purification-Crystallization Method
Bo LiYonggang WeiHua WangYindong YangYungui Yin
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2019 Volume 59 Issue 1 Pages 201-207


Blast furnace sludge (BFS) is an industrial waste generated during ironmaking, which contains approximately 10% Zn, 25% Fe and 24% C and is a valuable secondary resource of zinc. In this study, ZnSO4·7H2O was produced using BFS by the combination of acid leaching, iron and calcium precipitation, concentration and crystallization. The effects of different factors and operation steps on zinc recovery were investigated, and the optimum parameters of the treatment process were obtained as follows: Acid leaching was carried out at 60°C for 10 min using sulfuric acid with the concentration of 150 g/L and a liquid to solid ratio at 3 mL/g; Iron precipitation was performed at 25°C using the liquid solution with pH value in a range of 4.0–4.4 and the H2O2 dosage of 60 mL/L; Calcium precipitation was conducted at 60°C for 40 min with the ZnF2 dosage of 7.5 g/L. The recovery efficiency of zinc was approximately 95% and the purity of ZnSO4·7H2O in the product reached 99.57%. The obtained results indicate that the proposed process in this work can successfully recover Zn from BFS with high efficiency and short production route.

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© 2019 by The Iron and Steel Institute of Japan
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