Abstract <p>Pyrometallurgical smelting of high-grade nickel matte from sulfide ores generates significant quantities of high-value nickel converter slag. To address the challenge of unsatisfactory metal recovery caused by the inefficient separation of matte from slag when matte is used as a capture agent during the cleaning of nickel converter slag, we propose a reduction smelting–iron capture process for the efficient recovery of Ni, Co, and Cu in nickel converter slag. Mineralogical analysis, slag design and reduction thermodynamic analysis of the nickel converter slag were conducted, along with equilibrium calculations for the slag–matte–alloy system and the Fe–Ni–Co–Cu–S wide solution system. The experimental results demonstrated highly selective enrichment of valuable metals within the collector alloy along with effective separation of the alloy from the slag. The collector alloy contained distinct Fe–Ni–Co alloy phase and copper matte phase with distinct phase boundaries. Compared with matte, Fe exhibited stronger affinity for Ni and Co and functioned as a predominant capture agent. The optimized experimental conditions included 12 wt pct CaO addition, 3 wt pct coke addition, a smelting temperature of 1350 °C, and a holding time of 60 minutes. Under these conditions, the recoveries of Ni, Co, and Cu reached 92.55, 90.97, and 95.63 pct, respectively, with their concentrations in the residual slag reduced to 0.32, 0.09 and 0.16 wt pct, respectively. Pilot-scale tests and preliminary economic evaluation revealed the industrial application potential of this process.</p> Graphical Abstract <p></p>