Abstract: A low-grade copper-nickel ore in Qinghai contains 0.11% copper，0.49% nickel and 25.23% MgO. Copper-nickel minerals mainly exist in the form of sulfide minerals. The mineral composi‐ tion of the ore is complex，the dissemination is closely related，and the magnesium-containing gangue con‐ tent is high and easy to mud，which causes great difficulties in the enrichment and recovery of copper and nickel. In order to comprehensively recover the valuable elements，the copper-nickel mixed flotation pro‐ cess was adopted. Sodium silicate was used as dispersant，CMC was used as magnesium-containing gangue inhibitor，CuSO4 was used as activator，and butyl xanthate was used as collector. Under the condi‐ tion of grinding fineness of -0.074 mm accounting for 75%，the copper-nickel mixed concentrate with cop‐ per grade of 2.21%，nickel grade of 9.22%，MgO content of 3.45%，copper recovery rate of 73.18% and nickel recovery rate of 71.24% was finally obtained by two-roughing，three-cleaning and two-scavenging closed-circuit flotation process. The efficient recovery of low-grade copper-nickel resources provides a technical basis for the development and utilization of similar ores.

Key words: low grade copper-nickel ore, copper-nickel bulk flotation, magnesium-containing gangue