Abstract: Due to the unreasonable once alloy recovery process and the working condition of the equipment in nickel matter grinding-flotation plant， the recovery of once alloy is not ideal， which not only seriously affects the recovery of the followed precious metals， but also adversely affects the subsequent smelting process. Therefore， the study on once alloy recovery was conducted on the mineral process mineralogy research of second stage returning sands from once alloy enrichment， to find out the reasonable process reform project. he mineralogy research shows that the main minerals in the second-stage classifier sand are nickel matte， Cu-Fe-Ni alloy and porphyrite； the particle size of nickel matte and porphyrite is mainly 27~150 μm， and the particle size of Cu-Fe-Ni alloy is coarse， 70% or more is larger than 75 μm； the coarse-grained Cu-Fe-Ni alloy have high degree of liberation，and the fine-grained alloy is mainly associated with nickel matte and porphyrite. Laboratory test shows that the coarse alloy screening—re-grinding on the undersize（-75 μm account for 70%）—low intensity magnetic separation is the reasonable process. The total recovery rate of precious metals has increased significantly to over 95%. Optimize the process according to the laboratory test result， the S content of the alloy is 8.94%， the recovery of Pt， Pd， Au are 99.38%， 94.07% and 96.12%， which is significantly better than the production index before the optimization. Therefore， this process is the reasonable process for the recovery of the alloy， and the lower S content creates favorable conditions for subsequent smelting.

Key words: Nickel matte, Cu-Fe-Ni alloy, MLA；Magnetic separation, Process optimization