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With the rapid development of China's iron and steel industry, the steel industry demand for iron ore increased year by year, the high-grade bonanza easy to smelt iron ore resources dwindling, some complex iron comprehensive development and utilization of mineral resources has important practical significance. The red mud is the main waste generated in the the alumina industrial production process, which has a price element has the value of comprehensive development and utilization. Red mud of this study is to Guangxi high-speed rail Sanshui bauxite by the Bayer process red mud, red mud with high iron, aluminum, silicon oxide, aluminum, iron disseminated relationship is very complex, part of the aluminum form of isomorphous minerals iron, the conventional method is difficult to separate the iron and gangue minerals, coal-based - direct reduction process can achieve the separation of iron and other gangue minerals. In this paper, the use of X-ray diffraction, optical microscopy, scanning electron microscopy and other analytical methods to study the reaction behavior of the direct reduction of iron, aluminum, silicon, and to provide theoretical guidance for containing high alumina, silicon iron minerals restore sorting papers The main conclusions and innovations are as follows: (1) deficit peat based direct reduction - magnetic separation study: With the reduction temperature, reduction time, magnetic separation effect of the reduction products increased significantly. When the reduction temperature of 1150 ℃, reducing time 180min the grinding fineness-0.074mm content accounted for 89.7%, and the magnetic field strength of 8 × 10 4 A / m conditions to obtain the magnetic concentrate TFe 79.34% 72.07% and iron recovery of iron concentrate. (2) the response behavior of the red mud: red mud mineral heat during the restore process a series of phase-change reaction goethite, gibbsite, boehmite, kaolinite first dehydrated and then change as iron oxide, alumina and silica and the like. Reaction thermodynamic analysis shows that in the reduction process, iron oxide reduction generated FeO phase and Al 2 O 3 2 reaction fayalite and SiO , and iron spinel, unfavorable to the formation of these compounds FeO phase reduced to metallic Fe phase. Use of optical microscopy, X-ray diffraction, scanning electron microscopy (SEM) The the red mud Restore show that the reduction products of iron grain particle size distribution of dispersed; generate fayalite and iron spinel and other low melting point reduction difficulty and low melting point material wrapped iron grain particles and hinder the diffusion and migration of reducing gas, and reductive separation is difficult; reduction behavior of aluminum, silicon, the effect of iron oxide show that the mutual diffusion between the aluminum, silicon oxide and iron oxide, and occurs solid-phase reaction, the greatest impact on the reduction of iron in FeO large number generation phase, with reduced impact gradually decreases, alumina relative to silica, affect the degree of reduction of iron large. (3) The additive to strengthen red mud restore studies showed that: be used alone or used in conjunction with the CaF 2 Na 2 CO 3 as effective as two temperature reduction 1150 ℃, the reduction time 180min, the grinding fineness-0.074mm content accounted for 77.3%, magnetic separator magnetic field strength 8 × 10 4 A / m under the conditions, with addition of 5? F 2 5% is of Na 2 the CO 3, restore the product obtained by grinding and magnetic separation concentrate TFe grade of 85.14%, iron recovery rate of 87.89%. The Additives to promote the mechanism of reduction of red mud analysis showed the CaF 2 and of Na , 2 CO 3 reduction process fayalite and iron spinel formation to inhibition of FeO phase can be more effectively reduced to metallic iron, and the grain of the metal iron is easy to grow and mutual merger into a continuous iron crystal phase, metallic iron and other low-melting material interface to restore the separation effect significantly.
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