Abstract: The stockpile of iron tailings in China exceeds 10 billion tons, with about half consisting of refractory hematite/limonite ores. The efficiency of conventional sorting methods for these ores was low and costly. Magnetization roasting is the most effective technology for utilizing refractory iron ore, with the primary challenges being the efficient magnetization of iron minerals and the separation of impurities. In this study, municipal sludge (35% moisture content) and iron tailings were used to recover iron resources from typical sulfur-bearing and polymetallic refractory iron tailings by synergistic magnetization roasting technology. Under optimal roasting conditions (roasting temperature of 800 ℃, roasting time of 30 min, and municipal sludge doping of 15%), the resulted iron concentrate achieved an iron grade of 63.11%, an iron recovery rate of 96.23%, and impurity contents of sulfur, phosphorus, and aluminum all met the index requirements of C60 in GB/T 36704—2018 Iron Ore Concentrate. The study provided a new approach for the efficient resource utilization of iron tailings.

Key words: municipal sludge, magnetization roasting, resource utilization, iron tailings