Abstract: A high magnesium copper-nickel ore contains nickel 0.76%,copper 0.16%,magnesium oxide 25.12%.Copper minerals are mainly chalcopyrite,nickel minerals are mainly pentlandite,gangue minerals are mainly tremolite,talc,serpentine,olivine,diopside and less chlorite.The contents of harmful impurity components such as talc,serpentine and chlorite are as high as 42%.The oxidation rate of copper and nickel in the ore is low,and the primary copper sulfide occupies 87.50% of the total copper,and the nickel sulfide occupies 98.68% of the total nickel.In order to obtain the low magnesium copper nickel concentrate,the ore dressing tests were carried out.The results show that under the ore grinding fineness of -0.074 mm accounted for 70%,and by the process of two-roughing,two-scavenging and two-cleaning,following by two scavengings for concentrate 1 and combining tailings from cleaning concentrate 2 with concentrate of scavenging 1,and other middles back to the flowsheet in turn,the copper-nickel concentrate with copper grade of 2.28%,nickel grade of 11.81%,copper recovery rate of 70.37%,nickel recovery rate of 76.20%,magnesium oxide of only 4.38% was obtained,which reaches first quality standards (nickel grade of more than 10%,magnesium oxide of less than 6%);The key to successfully inhibit magnesium is adding the modified CMC inhibitors into cleaning stages (with the total addition of 480 g/t).The total amount was,which was a kind of high effective inhibitor for gangue minerals containing magnesium developed by Beijing General Research Institute of Mining and Metallurgy.The test process has advantages of stable operation,low reagent consumption and high efficiency,and is suitable for treatment of the ore.

Key words: Copper-nickel ore, Magnesium oxide, Talc, Serpentine