Abstract: Magnesium ions are often associated with quartz minerals. In order to research the effect of magnesium ion on the quartz flotation by sodium oleate， the flotation tests of pure quartz minerals were carried out. The mechanism of magnesium ion activating quartz was studied by Zeta potential test， solution chemistry calculation and infrared spectroscopy analysis. The results showed that: ①sodium oleate can not float quartzwithout magnesium ion； The flotation recovery rate of quartz can reach 92.40% under the condition that the pulp pH=10.5， the concentration of magnesium ion is 3.75×10^-4 mol/L， and the concentration of sodium oleate is 6.25×10^-4 mol/L. ②Zeta potential analysis shows that magnesium ion adsorbed on the surface of quartz is the active site of sodium oleate adsorption， so magnesium ion has an activation effect on sodium oleate flotation of quartz. ③Solution chemical analysis showed that the main active composion in the process of magnesium ion activation of quartz was MgOH⁺. ④Infrared spectroscopy analysis showed that sodium oleate can adsorb to the surface of quartz particles with the help of magnesium ion.

Key words: Quartz, Magnesium ions, Sodium oleate, Activation