Abstract: The growing demand for nickel and cobalt in the new energy sector necessitates efficient extraction methods from limonitic laterite ores. This study demonstrates the effectiveness of sodium sulfate as an additive to enhance the co-enrichment of nickel and cobalt during solid-state reduction. Na2SO4 promotes the formation of two distinct liquid phases, low-melting-point FeS-FeO-Fe and NaAlSiO4-NaFeSiO4, facilitating the migration and aggregation of Ni-Co-Fe alloy particles, leading to a high-grade alloy powder with 11.98% Ni and 0.88% Co, and recoveries of 94.03% and 80.16%, respectively. Ni-Co-Fe particle growth is mainly driven by the FeS-FeO-Fe eutectic melt, aligning with a liquid-phase sintering mechanism. Pilot-scale rotary-kiln experiments validate the industrial feasibility of this approach, offering a promising solution for the sustainable extraction of these critical metals.