Abstract: In the flotation process of lead-zinc sulfide ore， a large amount of lime is used to inhibit pyrite， resulting in problems such as high pH of pulp and pipe blockage. The new inhibitor HS-1 could replace part of lime to achieve efficient separation of lead， zinc and sulfur. In order to further improve the interaction mechanism of HS-1 with galena， sphalerite and pyrite， the inhibition mechanism of HS-1 was studied based on the flotation test results of pure minerals. The results showed that: ① When the pH value of pulp is 10， the combination of ethylthio-nitrogen and ammonium butanyl (molar ratio of 2∶1) as collector and HS-1 as inhibitor can effectively inhibit pyrite and partially inhibit sphalerite， while the flotation behavior of galena has little effect. ② The inhibitor HS-1 has little effect on the adsorption of collector on galena surface， and reduces the adsorption amount of ethylthio-nitrogen and ammonium butadiene black drug on sphalerite surface， and effectively inhibits the adsorption amount of combined collector on pyrite surface. ③ When the pH is of 10， HS-1 and composite collector successively react with three kinds of pure mineral， the surface of the minerals occurred the HS-1 infrared characteristic absorption peak， and the characteristic absorption peaks of the collector in the surface of galena has no obvious change， the collector absorption characteristic peaks in the surface of sphalerite and pyrite disappear， illustrating the HS-1 effectively inhibiton of the adsorption of collector on pyrite， and a certain inhibitory effect on sphalerite.

Key words: low-alkaline, HS-1, flotation for pure minerals, measurement adsorbing capacity, FTIR