Experimental Study On Recovering Iron From Bayer Red Mud And Preparing Building Materials With Residues

In this dissertation, recovery of iron was investigated from Red Mud (RM) of Bayer process as raw materials with direct reduction sintering process followed by magnetic separation, and building materials were prepared from magnetic separation residues after analyzing chemical and mineral compositions, and ferrous chemical phase.Results of chemical analysis showed that compositions of RM included Fe2O3 (27.93%), SiO2 (20.98%), Al2O3 (22.00%), and others were Ca, Na, Ti and so on. As XRD pattern showed, the mineralogical compositions in RM were quartz, hematite, limonite, cancrinite, calcite and illite. According to the chemical phase analysis, most of iron existed as hematite- limonite ore, followed by FeSiO3, FeCO3 and FeS.Roasting temperature, duration of roasting, additives and coal rations were primary factors of the reduction roasting experiment. According to the orthogonal experimental data, the effect of these factors on TFe was not identical with effect on MFe/TFe or recovery ratio. Considering all guide lines of test, better conditions of reduction roasting were obtained: 1300℃roasting for 110min with coal powder: RM =18:100, additives: RM=6:100. Under these conditions, the TFe of concentrate we got was 88.77%, with 97.69% metallization degree and recovery ratio of iron was 81.40%. The production of iron concentrated could be used as DRI, raw material of steel-making.Under above conditions, primary elements of residues were O, Si, Al, Na, Ca, and primary mineralogical compositions including nepheline,α-Al2O3, CaSiO3 and little iron. The residues mixed with 13% lime, steam curing for 11h at 80℃, after pressure molding at 20MPa. The compressive strength of specimen added up to 24.10Mpa. It was possible to make building materials such as steam- cured bricks from this residue.The result from a simple economic analysis showed that the process was feasible in the view of economics.