Flotation Research on Dolomite-Containing Magnesite Ore

Abstract

China has the largest magnesite reserve in the world. However, the high-grade magnesite resources are decreasing significantly with the development of the resources’ consumption. The treatment of the low-grade magnesite ore is becoming more important and of much interest to researchers. In this paper, the floatability of several pure minerals including magnesite, dolomite, and quartz and their interactions when using different collectors were investigated. In the flotation system of lauryl amine, compared with magnesite, the floatability of dolomite was higher, but was much lower than quartz. In the flotation system of sodium oleate, magnesite and dolomite had good floatability but quartz could hardly be floated. Sodium hexametaphosphate inhibited dolomite more strongly than magnesite. When pH was above 9, the inhibitory effect on two minerals was attenuated, and in the pH range of 9~12, the inhibitory effect of sodium silicate on dolomite was very strong, while magnesite still had good floatability. Magnesite and dolomite crystal structure similar and the mass contents of surface oxygen were respectively 52.42, 48.65. relative density that was the ratio of metal cation to anion （∑Mn+/∑O2-）, respectively: 0.3264,0.4327. The mass contents of surface oxygen and relative density affected the surface electric properties, and therefore the isoelectric point of dolomite was higher in solution.Based on crystal chemistry formulas, the Mn+-O2- bond parameters were calculated. The electronegativity of O linked with Ca in dolomite was much higher than that linked with Mg in magnesite and dolomite. Because of the strong electrostatic forces, the floatability of dolomite was higher in the flotation system of lauryl amine. As the solubility product of calcium oleate is bigger, the floatability of dolomite which compared to magnesite is much higher in the flotation system of sodium oleate. After the flotation experiments of pure minerals, a novel flotation system for recovering magnesite concentrate from low-grade magnesite ore was developed. For run-of-mine ore produced in Liaoning China, the results of flotation experiments showed that a magnesite concentrate containing 46.94 percent MgO, 0.30 percent SiO2, 0.76 percent CaO can be produced and 76.02 percent of the magnesite can be recovered through the process.