Dissolved iron exerts significant effects on mineral leaching, impurity removal, and solution purification in the zinc hydrometallurgy process. To date, iron oxidation and migration behaviors are yet to be fully understood and further research on effective regulation mechanisms of iron is required. In this paper, zinc sulfide concentrate was used as the research object. The behaviors of both Zn and Fe during pressure leaching were investigated for varying temperature, acid addition, and leaching time. At temperature of 100~160 °C, H₂SO₄/Zn ratio of 0.9:1–1.25:1, and leaching time of 0.5–2.5 h, the zinc extraction increased with temperature, acidity and leaching time. The iron extraction, however, varied differently with increasing temperature, acidity and leaching time: (A) it increased with temperature to 150 °C and then decreased at higher temperature, and (B) displayed an initial increase followed by a decrease with respect to the leaching time. Based on the characteristics of the residue phase, chemical phase analysis was used to analyze the residue in detail. The extent of dissolution of iron-containing minerals and the extent of precipitation of ferric ions during the leaching process were quantitatively calculated.

Steel slag, clay, quartz, feldspar, and talc were mixed to prepare steel slag ceramics. Crystalline phase transitions, microstructures, and the main physical-mechanical properties (water absorption, linear shrinkage, and flexural strength) of steel slag ceramics for various MgO/Al₂O₃ ratios were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and mechanical testing. The results indicated the significant effect of the MgO/Al₂O₃ ratio on these properties. A decrease in the MgO/Al₂O₃ ratio resulted in a major crystalline phase transformation from quartz and pyroxene phases to quartz and anorthite phases. High MgO content facilitated production of pyroxene phases. High Al₂O₃ content favored production of anorthite phases. The water absorption of all the samples (below 0.5%) met the Chinese national standard requirements. Samples with an MgO/Al₂O₃ ratio of 0.6 exhibited excellent flexural strength, reaching 62.20 MPa. FactSage software was used to predict batch viscosity, which increased with decreasing MgO/Al₂O₃ ratios.