Abstract: In order to effectively improve the production efficiency of grinding operation in a mineral processing and smelting plant，ensure the product fineness to meet the standard and significantly reduce the production cost，the problems of the original two-stage grinding process such as high grinding cost，only 1.2 t/ h machine-hour processing capacity and substandard product fineness（- 0.045 mm accounted for only 83%）are studied.Through comprehensive process technology analysis，the feasibility of the new process of one-stage grinding+classifier pre-classification is demonstrated in depth. The optimal operating parameters are determined by a large number of experiments and successfully applied to the production site.The produc⁃ tion practice shows that the processing capacity of grinding machine-hour is increased to 1.5 t/h，and the production efficiency is improved. The fineness compliance rate of the product is increased to more than 90%，the grinding index is guaranteed，the comprehensive benefit is increased by 1.102 5 million yuan，the cost per ton of ore is reduced by 12.47 yuan，and the annual cost is saved by 0.249 4 million yuan.The one�stage grinding + classifier pre-classification process has high applicability and superiority，solves the prob⁃ lems existing in the original process，and has significant economic benefits. It has reference value for other similar concentrators.

Key words: two-stage grinding, one-stage grinding, grinding operation, grinding fineness, process optimization, production transformation