Abstract: Aiming at the problems of hardly no selectivity，poor liquidity and dispersion of fatby acid at normal temperature，heating was needed in flotation process，influence of hydroxyl oxime acid collaborative fatty acids on solution viscosity，surface tension，and Zeta potential were studied.Results indicated that，fatty acid has poor fluidity at low temperature，temperature and revolutions intensiby has a great influence on the viscosity，fatty acid compound alkyl hydroxamic acid can effectively reduce the viscosity of fatty acid，fatty acid and alkyl hydroxamic acid has strong surface actively，they can effectively reduce surface tension of pure water;with fatty acid dosage of 400 mg/L,alkyl hydroxyl oxime acid dosage of fatty acid 0.5 times，pH=6，dolomite and apatite surface point difference is the largest.Dolomite and apatite single mineral flotation test results show that with fatty acid dosage of 400 mg/L,alkyl hydroxyl oxime acid dosage of fatty acid 0.5 times，pH=6，dolomite and apatite recovery difference is 87.88 percentage points higher than that of no hydroxy oxime acid by 14.34 percentage points,adding hydrixyl can increase separation index between apatite and dolomite.Mineral infrared spectrum showed that mixed collector with dolomite in physical adsorption and chemical adsorption，with only a small amount of apatite physical adsorption.

Key words: Hydroxamic acid, Fatty acid, Synergistic effect, Apatite, Dolomite, Flotation