Low-grade laterite ores are notoriously refractory to conventional physical beneficiation methods because of the fine dissemination of nickel within a complex matrix of hydrated iron oxides and silicate minerals. Meanwhile, red mud, a highly alkaline solid byproduct generated during bauxite refining, poses significant environmental and disposal challenges. To address both issues, a co-reduction and magnetic separation (CRMS) process has been proposed for the simultaneous treatment of laterite ore and sintering red mud (SRM), and the efficiency of nickel and iron recovery was systematically evaluated, supported by kinetic and microstructure characterization. The results showed that the kinetics of CRMS process was best described by the AE0.5 model (kinetic equation of \(\left[ { - {\text{ln}}\left( {1 - \alpha } \right)} \right]^{2} = 4.01 \times exp\left[ { - 6.226 \times 10^{4} / \left( {{\text{RT}}} \right)} \right]t\) ), and the apparent activation energy decreased from 70.37 kJ/mol in the absence of SRM to 62.26 kJ/mol when 50% SRM was added, demonstrating a significant catalytic effect on the reaction rate. Notably, calcium-bearing minerals in SRM react with MgSiO3 and Mg2SiO4 from the laterite to form low-melting-point minerals such as diopside, gehlenite, and akermanite. All these eutectic-forming reactions promote partial slag melting, enhance mass transfer, and facilitate the coalescence and growth of ferronickel particles, increasing their mean particle size from 4.5 μm to 10.3 μm. Under optimum co-reduction conditions (1300℃ for 80 min with 12% bituminous coal), a ferronickel concentrate containing 3.05% Ni and 80.62% Fe was obtained, and the corresponding recoveries of Ni and Fe were 95.74% and 93.93%, respectively. This study highlights the potential of the CRMS process as an efficient and environmentally beneficial strategy for the integrated valorization of low-grade laterite ores and red mud, enabling clean, resource-efficient metal recovery through waste-to-resource transformation.
