Magnetic Ni-Zn spinel ferrite nanopowder from toxic Zn-bearing electric arc furnace dust: A promising treatment process

Abstract

Zn-bearing electric arc furnace dust (ZEAFD) generated as a by-product of steel manufacture is classified as a toxic solid waste. To date, there has been little research concerning facile and efficient utilization of the valuable metallic elements (such as Zn, Fe, Mn and Cr) in this material. In this study, a metal co-doped (Ni,Zn)Fe2O4 nanopowder having excellent magnetic properties was successfully synthesized by a solid state calcination method based on adding Ni(OH)2 to the ZEAFD to compensate for a lack of divalent ions. The effects of the ZEAFD to Ni(OH)2 mass ratio and of the calcination temperature on the phase transformations, microstructures and magnetic characteristics of the resulting ferrites were investigated using various analytic techniques. A pure phase metal co-doped (Ni,Zn)Fe2O4 nanopowder having a higher saturation magnetization (57.3 emu·g−1) and lower coercivity (58.8 Oe) was obtained when the mixture was calcined at 1000 °C for 2 h with a mass ratio of 2:0.9, followed by washing with dilute acetic acid (pH = 2.88). This synthesized metal co-doped ferrite was also assessed using the United States Environmental Protection Agency toxicity characteristic leaching procedure and found to be non-toxic. This process provided overall dust utilization percentages as high as 76.0%.