Abstract: Four kinds of serpentine with different grain size were selected， and the modified Hallimond tube was used to investigate the effect of conditioning time on the recovery of brucite and serpentine. By analyzing the properties of pulp pH， Mg²⁺ concentration， Zeta potential， contact angle and pulp viscosity， the water solubility of serpentine and its effect on the floatability of brucite by sodium oleate were systematically studied. The results showed that with the increase of conditioning time， the solubility of Mg²⁺ on serpentine surface increases gradually， resulting in reduction of serpentine Zeta potential. Furthermore， the oleate ion reacts easily with Mg²⁺ in solution to form magnesium oleate， so a large amount of oleate ion is consumed， resulting in a lower recovery rate of brucite. The finer the particle size of serpentine and the longer the conditioning time are， the greater the viscosity of the serpentine pulp is， which leads to the enhancement of foam stability during the flotation process， resulting in an increase in the foam entrainment rate of serpentine.

Key words: brucite, serpentine, water solubility, foam entrainment, flotation