Zero-Waste Recycling Method for Nickel Leaching Residue by Direct Reduction–Magnetic Separation Process and Ceramsite Preparation

In this paper, a novel process for beneficiation of metallic iron from nickel leaching residue and preparation of ceramsite from tailings by direct reduction–magnetic separation process is reported. The optimal conditions for direct reduction process were 1100 °C roasting temperature, 120 min duration, and 30 wt.% reductant dosage. The reduced sample was benefited from low-intensity magnetic separation. This process yielded an iron concentrate of 82.32 wt.% grade and 78.05 wt.% recovery. Hence, this metallic iron could be used as a feedstock for the steel industry. Tailings of the magnetic separation procedure were used to prepare ceramsite. Optimal conditions for preparing ceramsite were: 55% magnetic separation tailings, 20% silica, 15% fly ash, 10% charcoal, a 1150 °C roasting temperature, and a holding time of 30 min. The ceramsite properties met the requirement of CJ/T299-2008 National Standard. These results suggested that developing this solid waste would have environmental and economic benefits.