Study On The Technology Of Iron Recovery From High Iron Content Alumina Red Mud

With China’s sustained and rapid economic development, the most important metal which to support the sustainable development of national economy—iron and aluminum which consumption is also growing. Because of the domestic iron ore and bauxite ore supply and demand contradiction is highlighting, the shortage of resources, the dependence on foreign resources become more and more seriously. Red mud is the production process of alumina bauxite after dissolution of alumina produced waste slag. It main componentsas follow:Fe2O3, Al2O3, SiO2, CaO, TiO2, REO etc.. Each It alumina production create about0.8-1.5t red mud. The cumulative stack stock to reach2tons. Red mud amount storage, not only occupy the land and waste of resources, but also easy to cause environmental pollution and potential safety hazard.In this paper the valuable metals iron from red mud recycling is studied. The reinforced direct Reduction-Magnetic separation process, using alumina red mud preparing metal iron for the purpose, to calcine the metallization rate, magnetic separation concentrate grade and recovery rate of TFe Fe as the evaluation index, to examine the different kinds of additive content, reduction temperature, reduction time, grinding fineness, the strength of the magnetic field on the direct Reduction-Magnetic separation of red mud effect of. At the same time to explore another magnetic products-non magnetic material recycling, using sulfuric acid leaching method recovery and enrichment of the valuable components.Alumina red mud roasred under additive (6%sodium carbonate and6%sodium sulfate) condition, in which the iron is reduced to metallic iron, and then through weak magnetic separation to be consistent with the requirements of steelmaking sponge iron. The optimum conditions are: reducing temperature of1050℃, reducing time of60min, grinding time of10min, grinding concentration of50%, the strength of the magnetic field of1000Gs. In this condition the concentrate containing90.16%iron and the recovery of iron up to94.95%.Thermodynamic studies show that aluminum and silicon compounds will react with iron oxide reduction reaction intermediates wustite in high temperature and reducing atmosphere. Iron, aluminum and silicon compound which produced by this process cannot continue to be reduced, thus affecting the reduction of iron metallization rate. When under the addition of sodium salt additives, aluminum and silicon compounds in high temperature reduction process priority and sodium reacts to produce sodium silicate, iron oxides, which can successfully reduced to metallic iron.Reduction product of microstructural studies indicate that in sodium carbonate solely in the direct reduction of the red mud process, reduced to generate the metallic iron grain distribution is not concentrated, reducing the metal grains have gathered together, so magnetic separation and the non-magnetic material cannot be well separated during grinding, however in sodium sulfate acting alone, reduction products of metallic iron particles are larger, in grinding magnetic separation, which can be better separation with nonmagnetic substance. Taking into account the additive dosage and excess sulfur will join into the iron phase during reduction process, so use of sodium carbonate to replace part of the sodium sulfate as additive.