Research On The Reciprocal Influences Among Magnesium-Containing Ores In Flotation

Magnesium is one of the most abundant light metal elements on earth, and china has the richest magnesium resources with magnesite and brucite ores reserve taking the first place in the world, nevertheless china is also rich in some other magnesium resource such as dolomite, serpentine and talc. Therefore, the comprehensive utilization and research for the magnesium resource in china is significant for the industrial development of china and the world. However, the magnesium resources in china are decreasing with the industrial development and utilization, thus the exploration for low grade magnesium resource is a must. But it is difficult to beneficiate magnesium ores because the associate minerals are also other magnesium containing ores with similar characteristics and reciprocal influences in the beneficiation process. Based on this, in this dissertation the reciprocal influences among magnesium-containing minerals has been studied, which will be theoretically and practically meaningful for improving the resource utilization.The reciprocal influences in flotation are defined as the influences caused by the dissolution and adsorption of minerals, which leading to the activating or depressing effects on other minerals. In this dissertation, the reciprocal influences among six kinds of mineral including magnesite, dolomite, serpentine, talc, brucite and quartz were studied by crystal structure analysis, dissolution components analysis, zeta-potential analysis, contact angle measurements, scanning electron microscopy analysis and X-ray diffraction analysis, and chemistry bond calculation, solution chemistry calculation and E-DLVO theory calculation. Moreover, the single mineral floatability research was conducted by tests for the floatability and influences of reagents on the floatability of these minerals with sodium oleate and dodecylamine acetate as collectors. Finally, based on the results from single mineral flotation tests and reciprocal influences research, flotation separation processing technologies on magnesite and brucite ores from Liaoning were proposed.The research results of the crystal structure and floatability characteristics of pure minerals showed that:in sodium oleate flotation system, the floatability of six minerals is magnesite>dolomite>talc>brucite>serpentine>quartz; sodium hexametaphosphate depressed dolomite better than magnesite; sodium silicate had activating effect on talc and brucite. In dodecylamine acetate flotation system, the floatability of the six minerals was quartz>talc>dolomite>brucite>serpentine>magnesite.The research results of the reciprocal influences of magnesium-containing minerals showed that:in sodium oleate flotation system, without any reagents, adding gangue minerals, especially dolomite, decreased the recovery of magnesite; adding serpentine had depressing effects on brucite. In sodium oleate flotation system with sodium hexametaphosphate as reagents, adding gangue minerals enormously decreased the recovery of magnesite, the influence order was serpentine> talc> quartz> dolomite, where the depressing effect of dolomite nearly vanished, which is beneficial for the beneficiation for magnesite; with more than 10% of gangue minerals, the recovery of quartz increased obviously. In sodium oleate flotation system with sodium silicate as reagents, the influence of gangue minerals on the recovery of magnesite is serpentine> talc> quartz> dolomite; with more than 20% of gangue minerals, the recovery of quartz increased obviously; the depressing effect of serpentine on brucite decreased, which is beneficial for the beneficiation of brucite. In dodecylamine acetate flotation system, dolomite increased the recovery of magnesite most while other minerals had minor effects; talc had some effects on quartz; serpentine or dolomite had minor effects on brucite.The research results of the mechanism of reciprocal influences of magnesium-containing minerals showed that:based on the E-DLVO theory calculation, in sodium oleate flotation system, the order of total E-DLVO energy between minerals with attracting force is magnesite-dolomite>magnesite-serpentine>brucite-dolomite>quartz-dolomite>magnesite-qua rtz>magnesite-serpentine>serpentine-brucite; the order of total E-DLVO energy between minerals with repulsive force is quartz-serpentine>quartz-talc>serpentine-dolomite. In dodecylamine acetate flotation system, the order of total E-DLVO energy between minerals with attracting force is quartz-talc>quartz-serpentine>quartz-dolomite>brucite-serpentine; the order of total E-DLVO energy between minerals with repulsive force is magnesite-serpentine>magnesite-talc>magnesite-dolomite>serpentine-dolomite>brucite-dolo mite>magnesite-quartz. Moreover, the larger the size of particle is, the bigger the total energy between them is. The reciprocal influences between minerals included the direct effects caused by the forces between particles as well as the indirect effects caused by the dissolution and surface transformation or minerals. When the particles had attractive force, adsorption will easy to happen between them. With sodium oleate as collector, sodium hexametaphospate could be used to decrease the adsorption of dolomite on magnesite, while sodium silicate could be used to decrease the adsorption of serpentine on bruicte.The last but not the least, flotation separation research on magnesite and brucite ores from Liaoning was conducted based on the previous research. The results of low grade magnesite ores separation research showed:with Na2CO3 to adjust pH value and decrease the side effects of dissolution ions, sodium silicate and sodium hexametaphosphate to disperse and reduce the adsorption effect, the closed-circuit two-step flotation flow sheet could obtain magnesite concentrate with MgO 47.71%, SiO20.16%, CaO 0.29% and MgO recovery 63.99%. The results of low grade brucite ores separation research showed:with sodium silicate to reduce the adsorption effects, in the optimum reagents condition, the closed-circuit flow sheet could obtain brucite concentrate with SiO22.87%, MgO 60.93%, MgO recovery 69.85%, which met the industrial requirements.The research of this dissertation has enriched the theory system of flotation methods for beneficiating magnesium-containing ores, and the research methods of exploring reciprocal influences in flotation system. Moreover, this research is a reference for the further research of magnesium-containing ores flotation separation and the research of reciprocal influences in other minerals.