Abstract: In the flotation environment with sodium oleate as collector， the floatability of magnesite， serpentine and quartz， the influence of serpentine on the floatability of magnesite， various particle fractions of the serpentine on the floatability of magnesite with different size range， and the influence of serpentine on the mixture of magnesite and quartz were researched and the mechanism was discussed. The results showed that the serpentine with different size range had individual effect on the floatability of magnesite with different grades and serpentine had strong inhibition effects on the flotation of magnesite. According to the mineral dissolved component diagram and SEM results， this was mainly because the dissolubility of the serpentine solution was relatively high， the ions of serpentine solution had relatively strong hydrophilicity which were easy to reunite with the Mg2+ and O2- ions on the surface of magnesite， that led to the increase of hydrophilicity of magnesite and decrease of the chance of sodium oleate attached on the surface of magnesite and therefore depress the floatability of magnesite.

Key words: magnesite, serpentite, sodium oleate, flotation, size range