Abstract: In order to verify the flotation performance of a new ester-based quaternary ammonium salt cationic collector M-3，which is prepared by Wuhan University of Technology，in the field of iron-increasing and silicon-reduction，pure quartz，pure magnetite and magnetic iron concentrate of Jiugang are selected as research object.It can draw the conclusion that:①the quartz recovery was 94.21%，but magnetite recovery was only 1.56% when the dosage of M-3 was 360 g/t，slurry temperature was 25 ℃,and the pH was 7.That is，M-3 has good collecting ability for quartz，but for magnetite，it has not.②The reverse flotation of SiO2 in iron concentrates(at feed grade of 49.98%) from magnetic separation operation with M-3 cationic collector achieved good indexes:the grade of iron concentrate was 56.39% and the iron recovery was 75.87% under the optimum condition of the dosage of M-3 400 g/t，the dosage of starch 200 g/t，and the pH 7.③FTIR test showed that both physical and chemical absorption happened to M-3 and quartz，but mainly physical absorption.Quantum chemistry calculation indicated that M-3 was more likely to interact with quartz，so M-3 was an effective collector in the field of iron-increasing and silicon-reduction.

Key words: Cationic collector M-3, Quartz, Magnetite, Magnetic iron concentrate, Reverse flotation, FTIR, Quantum chemistry