The induration process and oxidation kinetics of Hongge vanadium titanium-bearing magnetite (HVTM) pellets have been investigated by employing X-ray diffraction, scanning electron microscope, energy-dispersive spectroscopy, thermogravimetric and differential thermal analysis and thermogravimetric and differential scanning calorimetry. The results indicated that HVTM was a high-chromium vanadium-bearing titanomagnetite containing 1.48 wt-% Cr 2 O 3 , and the crystal stock strength was 625 N. The compressive strength of HVTM pellets could be improved by increasing the roasting temperature and roasting time. Under the optimum conditions of oxidation roasting at 1200°C for 15 min, the compressive strength was found to be 2893 N. The phase transformations of the valuable elements could be described as follows:

The recovery rates of vanadium, titanium, and chromium are much low in the current process of the vanadium titanomagnetite in Hongge region, China. In order to utilize Hongge vanadium titanomagnetite (HVTM) effectively, a novel clean process is proposed in this study, in which HVTM-oxidized pellets are reduced initially in shaft furnace and then melting separated. The influences of reduction temperature and ratio of w(H 2 ) and w(CO) on the reduction process and melting morphology of the reduced pellets are investigated. It is found that the rate and degree of reduction are improved with the increase of temperature and ratio of w(H 2 ) and w(CO). The appropriate temperature and ratio of w(H 2 ) and w(CO) are 1050 8C and 2.5, respectively. The phase transformations of the valuable elements during the reduction process can be described as follows: Fe 2 O 3 ! Fe 3 O 4 ! FeO ! Fe; Fe 9 TiO 15 ! Fe 2.75 Ti 0.25 O 4 ! Fe 2 TiO 4 ! FeTiO 3 ! TiO 2 ; (Fe 0.6 Cr 0.4 ) 2 O 4 , Fe 0.7 Cr 1.3 O 3 ! FeCr 2 O 4 ; (Cr 0.15 V 0.85 ) 2 O 3 ! Fe 2 VO 4 . The recovery rates of iron, vanadium, chromium, and TiO 2 are 98. 7, 88.27, 91.38, and 92.52%, respectively. The separated iron is a clean raw material for steelmaking; moreover, the titanium-rich slag can be used for further process to recover titanium. This study aims to provide theoretical and technical bases for the comprehensive utilization of HVTM and increase the recovery rates of valuable elements.

The reduction kinetics of Hongge vanadium titanomagnetite (HVTM)‐oxidized pellet with simulated gas compositions of dry pulverized coal gasification (DPCG), water‐coal slurry gasification (WCSG), Midrex, and HYL‐III is investigated in the current study. The experiments are carried out at temperatures ranging from 900 to 1050 °C, simulating the reduction zone in gas‐based shaft furnace direct reduction processes. The reduction degree is the highest when reduced with the gas composition of HYL‐III while the lowest when reduced with DPCG. The reduction degree, as well as the reaction rate constant and effective diffusion coefficient, is found to decrease in the order of HYL‐III > Midrex > WCSG > DPCG. The reduction process is controlled by interfacial chemical reaction at initial stage and by both interfacial chemical reaction and internal diffusion at later stage. The scanning electron microscope (SEM) coupled with energy‐dispersive spectroscopy (EDS) and X‐ray diffraction (XRD) are used to estimate the reduction mechanism of HVTM‐oxidized pellet with different gas compositions. This study aims to obtain scientific direction for reactor design and operational parameter determination of gas‐based shaft furnace, as well as provide both theoretical and technical basis for the comprehensive utilization of HVTM.

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This study presents an effective and cleaner process with hydrogen-rich gases that uses oxidation roasting followed by gas-based direct reduction and melting separation to recovery iron, titanium, vanadium, and chromium from Hongge vanadium titanomagnetite (HVTM). The process parameters were systematically investigated and determined to be roasting temperature at 1200°C, roasting time of 15 min, reduction temperature at 1050°C, volume ratio of H 2 to CO of 2.5, melting temperature at 1580°C, melting time of 30 min. Under optimized conditions, after melting separation, the recovery rates of iron, titanium, vanadium, and chromium were 97.9, 89.8, 96.7, and 97.8%, respectively. Furthermore, the melting separation mechanism was determined. The separated iron is a clean raw material for steelmaking and the Ti-rich slag can send for further processing to recover titanium. This study aims to provide a theoretical and technical basis for the comprehensive utilization of HVTM.

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