Sustainable valorization of lateritic nickel tailings: Valuable metals recovery and gas-purifying materials fabrication

• Na 2 CO 3 -assisted reduction achieves excellent Fe metallization from HPAL residue. • Hierarchical porous adsorbent from hydrothermal treatment shows high gas uptake. • Closed-loop recycling enables full-component utilization of HPLA residue. The massive generation of acidic iron-rich residue from high-pressure acid leaching (HPAL) of laterite nickel ore presents serious environmental and waste management challenges. This study develops an integrated pyro-hydrometallurgical process for the full-component recovery and upcycling of such residues. Key findings demonstrate that reduction roasting with Na 2 CO 3 enables production of high-grade iron concentrate (95.2 % Fe), while alkaline hydrothermal treatment of tailings facilitates extraction of Ca, Al, and Na, and concurrently converts silicon residues into hierarchically porous adsorbents. These adsorbents exhibit excellent gas adsorption performance (up to 5.49 mmol/g for NO) and selectivity in gas separation. The process is technically validated through pilot-scale trials, offering a sustainable strategy for transforming hazardous HPAL residues into high-value products.