Integrated High-Temperature Pretreatment and Coal-Based Reduction for Efficient Iron Recovery from Laterite Nickel Ore Acid Leach Tailings

The acid-leaching tailings from laterite nickel ore processing contain valuable secondary metal resources, especially iron, but pose environmental risks due to high sulfur content. This study investigates an optimized process combining heating pretreatment with coal-based reduction to enhance sulfur removal and maximize iron recovery from these tailings. Under optimal conditions—1000°C heating pretreatment, coal powder dosage of C/O = 2.5, reduction temperature of 1250°C, reduction time of 40 min, magnetic field strength of 1200 Oe, and grinding fineness with 90% passing – 91.1 μm—the process achieved significant improvements in product quality. Sulfur content in the magnetic concentrate was reduced to 0.114%, with a high-grade iron concentrate containing TFe of 91.30%, MFe of 90.67%, and a metallization degree of 99.31%. Characterization by comprehensive analysis confirmed the effective transformation of iron oxides to metallic iron, enhancing the magnetic susceptibility and facilitating efficient separation. This study provides a comprehensive framework for high-purity iron recovery from complex tailings, aligning with industrial demands and environmental objectives.