Characterisation and Carbothermal Reduction of a Murray Basin Ilmenite Concentrate

摘要

An ilmenite ore from the Murray Basin was initially characterised using combined X-ray FluorescencernSpectroscopy (XRF), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and ElectronrnProbe Microanalysis (EPMA) techniques. XRF analysis showed the ilmenite sample containedrn58.7 wt per cent TiO_2 and 26.2 wt per cent Fe2O3. Major impurities included: Cr_2O_3 (4.5 wt per cent),rnAl_2O_3 (2.7 wt per cent), SiO_2 (1.9 wt per cent), Mn_3O_4 (1.5 wt per cent) and MgO (1.1 wt per cent).rnManganese and magnesium were present as solid solution components within the ilmenite latticernwhile the elevated Al_2O_3 and SiO_2 levels were due to separate aluminosilicate gangue minerals.rnChromium was associated with discrete chrome spinel gangue phases of variable composition,rn(Fe,Mg)(Cr,Al)_2O_4. Quantitative XRD analysis of the sample identifi ed rutile (12 per cent), ilmenitern(11 per cent), and pseudorutile (67 per cent) as the main titanium-containing phases and chromerichrnspinels (seven per cent) as the major impurity phase. Minor quartz, aluminosilicates, zircon andrnmonazite were also present.rnThe ilmenite was mixed with synthetic graphite, pressed into pellets and reduced carbothermallyrnin nitrogen at 1200 and 1400℃ with C/O molar ratio of 1.2. Titanium oxide in the ilmenite wasrnconverted to titanium oxycarbonitride. Iron oxides were reduced to metallic iron. The Changes ofrnimpurities as a result of reduction was examined by SEM and EPMA analyses. Iron and chromiumrnoxides within Fe-rich chromite were reduced to form a Fe-Cr-C alloy. Mg-rich chrome spinels werernpartly reduced at 1200℃. Zircon particles were not reduced at 1200℃, but were signifi cantly reducedrnat 1400℃, with the particles becoming porous and the silicon being removed.