Research On Recovery Of Iron And Alumina From The Red Mud

The red mud is the waste residue from the productive process of alu mina. At present, the amount of the red mud stockpiling of our country is about200million tons, and it is predicted that the amount will reach350million tons by2015. The red mud could bring about a series of problems such as soil alkalization, landslides, debris flow, sand storm, and wasting of resources, which became the major factors that restricts the development of alu mina production.According to the characteristic of high content of Fe and Al2O3in bayer red mud, this paper firstly carried out experiments to recover iron by carbon hot reduction and recover alu mina by alkali lime sintering-leaching from the bayer red mud. On the basis, the reductive sintering method was applied to recover iron and alu mina. The main research results are listed as follows.(1)The recovery of iron by carbon hot reduction was effected by reduction temperature, reduction time, percentage amount of coke, ball-milling and magnetic separation, When reduction temperature is under900℃, Fe content in concentrate and Fe recovery rate was lower, recovery results was not perfect.(2)Increasing reduction temperature can boost CO concentration and speed up dissociation of complex compounds. Adding to appropriate mount of CaF2promotes activity of FeO and improve reductive degree of iron oxide of red mud. The Fe content in concentrate was90.25%, and the recovery rate was91.75%.(3)The alkali lime sintering-leaching was used to recover Al2O3. Experimental result demonstrated that when the sintering temperature was1050℃, the sintering time was50min, the mass fraction of w(Na2O· Fe2O3) was11%,[CaO]/[Fe2O3] was1.4, On above condition, the recovery rate of Al2O3could reach89.52%. Fe exists in dissolution slag in form of Fe2O3.(3)The recovery of Fe and Al2O3by carbon hot reduction-alkali lime sintering method firstly separate Al from the red mud by dissolution of the sintering clinker, and the separate Fe by magnetic separation. The appropriate condition of sintering the recovery rate of Al2O3was83.77%. The Fe content in concentration was64.08%, and the recovery rate was82.35%.Fe concentration can used in smelting iron in blast furnace.This can creates favorable conditions of recovery Ti and rare metal.