Effect of manganese(II) and magnesiumg(II) in zinc acid leaching solution on iron precipitation via the hematite process

Iron (Fe) removal is a critical step in the hydrometallurgical zinc (Zn) extraction process. Hematite, a stable Fe precipitate, offers an environmentally friendly option that complies with environmental protection standards. While existing research primarily focuses on hematite process technology, there is a lack of studies on how ions in ZnSO4 leaching solutions affect Fe removal efficiency and hematite particle size distribution. This study investigated the influence of manganese II (Mn(II)) and magnesium II (Mg(II)) concentrations and temperature on both Fe removal efficiency and hematite particle size distribution in ZnSO4 leaching solution. The results indicated that at various temperatures, the highest Fe removal efficiency occurred with an initial Mn(II) concentration of 10 g/L and an Mg(II) concentration of 15 g/L. As the concentrations of Mn(II) and Mg(II) as well as temperature increased, FeSO4 crystallization also increased, which adversely affected hematite precipitation. The average particle size of hematite decreases from 300 to 100 nm, resulting in a more uniform particle size distribution, which correlated with the homogeneous solution saturation precipitation mechanism. However, the number of rod-shaped, regular small particles decreases, while the number of irregular, blocky particles increased.