Abstract: In order to eliminate as much as possible the effect of unavoidable ions Ca²⁺ on the flotation of magnesite， the influence of Ca²⁺ on flotation behavior of magnesite and mechanism analysis under sodium oleate flotation system were investigated through pure mineral flotation experiments， Ca²⁺ flotation solution chemistry calculations and infrared spectroscopy analysis. The results indicated: ①Under the sodium oleate flotation system， Ca²⁺ showed a strong inhibitory effect on magnesite flotation in the case of pH of slurry between 7 and 12， and the inhibition effect strengthened with the increase of Ca²⁺ concentration. ②Ca²⁺ in the slurry is the main component which inhibited the flotation of magnesite. ③Under alkaline conditions in which pH=10， hydrophilic hydroxyl absorption peak was found on the surface of magnesite， which confirmed the adsorption of Ca²⁺ on the surface of magnesite.

Key words: Magnesite, Ca²⁺, Sodium oleate, Flotation