In this paper,the thermodynamics of the reduction of ilmenite using multiple gases(H_2/CO) was calculated.It is found that the metallization rate of 20.1%-98.8%,H_2 consumption rate of 43.0%-99.1%,and carbon deposition amount of 5.7 × 10^(-7) — 0.49 mol can be obtained based on the conditions of hydrogen volume fraction of 10%-90%and temperature of 450-1200 ℃.Experimental study was also carried out using synthetic ilmenite as initial materials and reduced in a static bed reactor at 1100 ℃.The metallization rate reaches 97%when the multiple gas(70%H_2/10%CO/20%Ar) flow rate is 120 ml·min^(-1).A thermogravimetric analyzer was used to measure the variation of sample weight caused by the deposition of solid carbon.The amount of carbon deposited during experiments reaches its maximum while the original hydrogen volume content is 20%.The experimental results are well consistent with the thermodynamic analysis.
The reduction of ilmenite concentrate by hydrogen gas was investigated in the temperature range of 500 to 1200°C.The microstructure and phase transition of the reduction products were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),and optical microscopy(OM).It was found that the weight loss and iron metallization rate increased with the increase of reduction temperature and reaction time.The iron metallization rate could reach 87.5% when the sample was reduced at 1150°C for 80 min.The final phase constituents mainly consist of Fe,M 3 O 5 solid solution phase(M=Mg,Ti,and Fe),and few titanium oxide.Microstructure analysis shows that the surfaces of the reduction products have many holes and cracks and the reactions take place from the exterior of the grain to its interior.The kinetics of reduction indicates that the rate-controlling step is diffusion process control with the activation energy of 89 kJ·mol-1.
