Abstract: There are some problems in the preferential flotation of copper sulfide copper ore in Gejiu， such as low dissociation degree of copper mineral monomer，large amount of sequential return circulation， and difficulty in improving the separation index. The regrinding and reconcentration test of medium ore was carried out，and the optimum process parameters were determined. The industrial practice shows that the closed-circuit process of one roughing-one cleaning-two scavenging，two-stage scavenging concentrate re⁃ turning to one scavenging，cleaning tailings and one scavenging concentrate merging，regrinding and recon⁃ centration is adopted. For the feed ore with copper grade of 1.586%，a copper concentrate with grade and re⁃ covery of 22.17% and 93.32% is obtained，which is 2.52 and 3.37 percentage points higher than the copper grade and recovery obtained by the original process. After the process optimization，the problems of deterio⁃ ration cycle and low separation index of medium ore sequence return are solved，and the resource utilization rate is improved. It can create direct economic benefits of about 986 million yuan per year.

Key words: copper sulfide ore, preferential flotation, regrinding, reconcentration