| Mineral resources are important material foundation of national economic construction and social development, and mining is an important basic industry of national economy. Magnesium resources is an important mineral resources, along with the rapid development of China’s magnesium industry, China has occupies a pivotal position in the global magnesium industry which developed into a large country of magnesium resources, production and export. But magnesium resources are nonrenewable resources, improve resource utilization and maintain the sustainable development of resources is important. In the paper, magnesite, dolomite, serpentine and talc are as the research minerals, the surface properties of minerals and magnesium in the surface properties of the solution and the flotation of minerals in different modifiers was studied, and identified the chemical characteristics of mineral crystals, the surface characteristics and the relationship between floatability relevant laws.According to the dissolution balance of mineral, the dissolved components in the solution of magnesite, dolomite, serpentite were calculated, and the solution composition and mineral composition of the surface electrical properties can be determined with different pH values, and predicted the PZC of magnesite, dolomite, serpentine were7.0,6.5,8.7. Four surface electrical properties of minerals magnesium and natural floatability significantly different. The natural floatability of magnesite and dolomite are good in SO and LA flotation system, the PZC of serpentine was high, the natural floatability of magnesite and dolomite are poor in SO and LA flotation system; talc have certain natural hydrophobic at the appropriate pH, and sodium dodecyl amine flotation of its performance are good.In SA flotation system, sodium hexametaphosphate and sodium silicate minerals have a certain inhibitory effect of magnesium, but the inhibitory effect and role of the range of pH values were different; sodium carbonate has activation on magnesite and dolomite in a wider pH range; sodium carbonate has a certain inhibitory effect on the serpentine at higher pH, but it was active on talc; sodium fluoride has an activation on magnesium in alkaline pH, but inhibitory in higher pH; starch has strong inhibitory effect on the magnesium minerals in strong alkaline pH; metal ions can inhibit the minerals magnesium, but the pH of10-12, the serpentite under the metal ions floating rapidly increasing, and metal ions on the activation of serpentine from strong to weak for the Ca2+> Mg2+> Fe3+> Al3+.In the LA flotation system, sodium hexametaphosphate and sodium silicate minerals have a certain inhibitory effect on magnesium; sodium carbonate has an activation in the alkaline pH, but inhibitory in higher pH; sodium fluoride on magnesite, dolomite, serpentine has activation only when the pH is greater than10.5talc activation; starch in strong alkaline pH inhibited strongly magnesium minerals; metal ions within a wide pH range of magnesium minerals have a certain inhibition.The crystal structure schematic of the unit cell and the coordination polyhedron constituted reveals the mineral and chemical composition of the relationship. Crystal structure of magnesium in the chemical bond theory calculations show that:magnesite and dolomite fracture of the bond is mainly Mg-O and Ca-0bond, in the So’of O in MgCO3and CaCO3were-1.128,-1.23; serpentine crystal structure of Mg-O easily broken, so that the surface of exposed serpentine ion Mg2+and O2-ions; talc surface only a small part of the Mg-O was broken. The surface of magnesium minerals was analysised by XPS, the surface oxygen content of magnesite, dolomite, serpentine, talc were50.19%,48.63%,64.34%,58.94%, the anions relative density (∑Mn/∑O2-) are:0.218,0.225,0.258,0.272.The solubility of magnesium carbonate minerals will affect the flotation process. In this paper, the solubility of magnesite and dolomite in water was simulated by PHREEQC software. The results showed that the effect of temperature on the solubility of magnesite and dolomite was different. When the solution pH was11, the lowest solubility of magnesite and dolomite respectively were12.48mg/L and10.05mg/L. Most of the metal cations and inorganic anions except for positional ions will increase the solubility. In the same solution, the solubility of magnesite and dolomite were14.03mg/L and3.16mg/L when the dissolution was in equilibrium. Solubility curve and the curve of mineral floatability of the relationship between a more consistent, it was helpful to the flotation process to reduce the solubility of mineral.Finally, low-grade magnesite flotation tests were carried out, and the principle of separation of the gangue minerals process were determined that based on technological mineralogy and pure magnesium mineral flotation test results. A new type of fatty acids collector was used. 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 containing46.94percent MgO,0.30percent SiO2,0.76percent CaO can be produced and76.02percent of the magnesite can be recovered through the process.In this study, the flotation characteristics of magnesite, dolomite, serpentine, talc in different agents in LA and OS flotation combined with mineral crystal chemistry and the solution chemistry were studied, the relationship of crystal chemistry characteristics, surface characteristics and the flotation were revealed. The results can provide the basis for flotation separation of magnesium minerals. The tests of purification of low-grade magnesite not only verified the correctness of the crystal chemical mechanisms, but also provided a guarantee for the sustainable development of magnesium industry which has a certain practical significance. |
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