Fabrication of Ni–Zn spinel ferrite with superior magnetic performance from electric arc furnace dust and iron scale

The Ni–ZnFe₂O₄ (Ni_xZn_1−xFe₂O₄, x = 0.4–0.7) spinel was synthesized using Zn²⁺ extracted from electric arc furnace dust (EAFD), nickel chloride hexahydrate, and Fe³⁺ extracted from iron scale as raw materials. The zinc was selectively extracted from EAFD using CaO roasting followed by NH₄Cl solution leaching. The ferric ion was leached from iron scale using HCl solution as acid lixiviant. The experimental results demonstrate a high level of efficiency in the extraction of zinc, with a rate of 97.5%, and the leaching rate of ferric ion is 96.89%. The composition of the leaching solution is primary zinc and iron with low calcium, which is beneficial to the preparation of spinel ferrite. The influence of Ni content (x) and calcination temperature on the synthesis and magnetic properties of Ni_xZn_1−xFe₂O₄ compounds was investigated by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. The results revealed that both Ni content and calcination temperature significantly affect the synthesis and magnetic properties of spinel Ni_xZn_1−xFe₂O₄. Under the conditions of Ni content set at x = 0.6, calcination temperature of 1100 °C, and a duration of 2 h, a spinel Ni_xZn_1−xFe₂O₄ with high saturation magnetization (M_s = 65.7 A m² kg⁻¹) and low coercivity (H_c = 0.056 A m⁻¹) was obtained.