<p>This research investigates the processes and mechanisms involved in the extraction of nickel from a specific complex copper-nickel ore (CNO) located in Xinjiang through chlorination roasting followed by magnetic separation. The ore, characterized by a copper grade of 1.12% and a nickel grade of 0.6%, exhibits a fine-grained disseminated distribution of metals, which complicates the efficient recovery of nickel using traditional beneficiation techniques. To tackle this challenge, the study systematically examined the impact of various parameters on nickel recovery during the chlorination roasting-magnetic separation process through single-factor experiments. Comparative experiments revealed substantial improvements, with the nickel grade increasing to 5.14% and the recovery rate achieving 91.97%, thereby significantly enhancing nickel enrichment. The response surface methodology (RSM) was adopted to construct a mathematical model, which effectively reduced the experimental cost. Comprehensive characterization of the micromorphology and crystal structure before and after the roasting process was performed using XRD and SEM–EDS analyses. This analysis clarified the phase evolution law occurring during roasting and provided insights into the state of nickel. The findings of this study contribute theoretical knowledge regarding the mechanisms of nickel recovery via chlorination roasting and establish favorable conditions for subsequent hydrometallurgical extraction of copper.</p> Graphical Abstract <p></p>