Selective extraction of zinc from high iron-bearing zinc calcine by reduction and magnetization roasting

A novel process that combined reduction roasting with magnetization roasting was developed to intensify the decomposition of zinc ferrite for the selective extraction of zinc from high iron-bearing zinc calcine. The decomposition mechanism of zinc ferrite was investigated in detail by thermodynamics analysis and roasting experiments. The results indicated that 94.65% of the zinc ferrite was decomposed into zinc oxide and ferrous oxide under the optimal reduction roasting conditions of 8 vol.% CO, 750 degrees C, 50 vol.% CO/(CO+CO2), and 90 min. The generated ferrous oxide was further converted to ferriferrous oxide by magnetization roasting under an air atmosphere at 450 degrees C for 30 min. After that, 93.62% of zinc contained in the calcine could be selectively extracted by low acid leaching, whereas more than 90% of iron was concentrated in the leaching slag in the form of magnetite, which could be recovered by the subsequent magnetic separation.