Sustainable Mining and Metallurgy

Leaching residue of laterite nickel ore, as a by-product of sulfuric acid high-pressure acid leaching (HPAL) for nickel and cobalt extraction, is rich in valuable metals such as iron and chromium. Its large-scale stockpiling is not noly a waste of resources but also has a risk of heavy metal contamination. This study used a reduction roasting-reduction smelting process to recover valuable metals from the leaching residue. The results show that under the conditions of adding 2.0% anthracite, roasting temperature of 900℃ and roasting time of 45min, the sulfur content of leaching residue decreases from 3.57% to 0.056% and the desulfurization rate reaches 98.69%, which can effectively eliminate the influence of sulfur on the subsequent smelting. For reduction smelting of the roasted calcine, under the conditions of carbon ratio 0.85, alkalinity 0.9, smelting temperature 1550℃ and smelting time 30min, the recovery rates of iron and chromium are 94.41% and 59.79%, respectively. The resulting alloy can partially substitute conventional steelmaking raw materials, while the slag is suitable for producing active admixtures. This process provides a novel technical pathway for the comprehensive resource utilization of laterite ore leach residue.