Hydrogen-assisted mineral phase transformation for iron recovery and sulfur removal from laterite nickel ore tailings

This study explores a hydrogen-assisted mineral phase transformation process with synergistic desulfurization for the efficient recovery of iron from the high-pressure acid leach (HPAL) tailings of laterite nickel ore. HPAL tailings containing 51.50wt% iron and 2.09wt% sulfur present environmental challenges due to their sulfur content. Pre-treatment at 950°C for 15 min successfully reduced the sulfur content to 0.295wt% and increased the iron grade to 57.66wt%. Further hydrogen-assisted mineral phase transformation at 520°C for 30 min, using 40vol% hydrogen and a gas flow rate of 600 mL·min^–1, resulted in a product with an iron grade of 61.00wt% and 90.11% iron recovery. The overall desulfurization rate reached 85.83% when wet scrubbing and limestone were used to capture the sulfur. This study demonstrates the efficiency of this hydrogen-assisted process for sustainable iron recovery and sulfur removal from laterite nickel ore tailings, with potential for industrial applications.