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Pre-oxidation of fines of magnetite containing materials is usually carried out to get better yield of metals. Titaniferous magnetite ore (TMO) is one kind of low-grade iron ore (around 45-50% of total Fe) with a significant amount of TiO2 (23.23%) and V2O5 (0.403%). TMO fines have been pre-oxidised at 973 K (700°C) for 9 h under air atmosphere. The effect of reduction of raw TMO fines as well as the pre-oxidised TMO fines using boiler grade coal in the form of cylindrical briquettes has been studied in the temperature range of 1273 K (1000°C) to 1473 K (1200°C) for periods of 10, 20, 30, 40 and 60 min to estimate the relative yield of iron. The influence of temperature and time on reduction experiments has also been investigated with XRD, FESEM analyses along with chemical analysis of the reduced samples. The most novel result is that the yield of Fe by direct reduction of raw TMO (92.42%) is even marginally better than that of reduction of pre-oxidised TMO (90.89%) at 1473 K (1200°C) for 60 min. Thus the single-step reduction of raw TMO is techno-economically more viable than the pre-oxidation followed by reduction technique. [ABSTRACT FROM AUTHOR]

Reduction behaviour of cold bonded self-reducing titaniferous magnetite ore (TMO) and lean grade coal briquettes have been investigated under isothermal condition. The reduction experiments of TMO-coal composite briquettes have been performed at varying temperatures ranging between 1273 and 1473 K for 3–60 min. The metallised briquettes are characterised by XRD and further FESEM. It can be inferred that the coal devolatisation and char gasification are solely responsible for the reduction process. The isothermal kinetic study has been performed considering the loss of oxygen fraction from the TMO which showed contracting geometry (CG 3 ) to be the initial mechanism followed by diffusion controlled mechanism (Jander kinetic model; D 4 ) in the later part of the reaction. The corresponding activation energies using Arrhenius Equation are evaluated as 93.42 and 179.80 KJ/mol, respectively. [ABSTRACT FROM AUTHOR]