Abstract: In order to efficiently utilize a molybdenum-bearing copper mine in Jiangxi Province，a new inhibitor KDY-2 is developed to solve the problem of long-term low recovery rate of concentrated mo‐ lybdenum caused by high alkali process of lime in concentrated copper-sulfur separation.The mechanism of the new inhibitor is studied by infrared test，and the industrial application test of low alkalinity copper sulfur separation is carried out on the basis of small laboratory test，and the industrial dosage of KDY-2 in‐ hibitor is determined.The test results show that the concentrated molybdenum recovery rate of the low alkali process in the industrial test jumps from 45.67% to 88.08% compared with the original high alkali process. At the same time，the copper concentrate grade increases by 0.93 percentage points，the copper recovery rate in the cleaning section increases by 0.12 percentage points，and the sulfur comprehensive recovery rate increases by 3.07 percentage points. The economic benefit is remarkable.

Key words: copper-sulfur separation, low alkalinity, inhibitor, industrial application, molybdenum recovery