Relationship between the Phases, Structure, MgO Migration and the Reduction Performance of the Pre-oxidized Vanadium-titanium Magnetite Ore in a Fluidized Bed

Abstract

This paper contrastively investigated the reduction behavior of raw and oxidized vanadium titanium magnetite ore (RVTM and OVTM) in a bubbling fluidized bed at 800°C under 75%N 2 -25%H 2 , and systematically revealed the relationship between the structure, phases change, MgO migration behavior and the reduction performance. Microstructure observations suggest that oxidization conditions greatly affect structural evolution, phase transformation of Fe-Ti oxides, and migration of MgO in OVTM. The reduction results indicated that the average metallization degree enhanced by 8-10% as the OVTM ore had high oxidization degree. When the RVTM ore was treated at 800°C, the reduction rate increased with the increase of oxidization degree, no significant difference was observed among these oxidized samples due to their similar internal and surface structure. However, the reduction rate of OVTM at 950°C depended on the oxidization time. The reduction rate of OVTM oxidized at 950°C for 2 h was faster than the one for 1 h, which was attributed to the better exsolution of MgO and the formation of bigger pores, even though both samples were fully oxidized and Fe 2 TiO 5 formed in the oxidization process.

Migration Behavior of the MgO and its Influence on the Reduction of Fe₃O₄–MgO Sinter

“…7) To solve this problem, many researchers adopted pre-oxidization to strengthen the reduction processes by controlling the ore phases and structure. [7][8][9][10][11] Studies have shown that dense structures can become porous, which was beneficial for the mass transfer and reaction. 9,12) From the view of phase…”

Effects of Preheating Temperature and Time of Hongge Vanadium Titanomagnetite Pellet on Its Gas-Based Direct Reduction Behavior with Simulated Shaft Furnace Gases

“…6) Compared with the BF process, several new processes on the basis of direct reduction containing coal of HVTM or other minerals have been widely studied. [7][8][9][10][11][12][13][14][15][16][17] Zhao et al 8) surveyed the reduction behaviors of FeO·V 2 O 3 and FeO·Cr 2 O 3 during coal-based direct reduction of HVTM and the effects on the elements distribution in the subsequent magnetic separation. Hu et al…”

Influence of Cr₂O₃ Addition on the Gas-Based Direct Reduction Behavior of Hongge Vanadium Titanomagnetite Pellet with Simulated Shaft Furnace Gases

“…22) Numerous studies on the gas-based direct reduction of HVTM or VTM were carried out. [23][24][25][26][27][28][29] Li et al 23) investigated the correlations between roasting characteristics of HVTMP and its subsequent reduction behaviors. Pan et al 27) studied the reduction behavior of raw and oxidized VTM in a bubbling fluidized bed.…”

“…[23][24][25][26][27][28][29] Li et al 23) investigated the correlations between roasting characteristics of HVTMP and its subsequent reduction behaviors. Pan et al 27) studied the reduction behavior of raw and oxidized VTM in a bubbling fluidized bed. As mentioned previously, the contents of Cr 2 O 3 in these studies were lower than 1.5 wt%, and it is uncertain whether Cr 2 O 3 affects the gas-based direct reduction of HVTMP especially under condition of relatively higher content of Cr 2 O 3 with simulated shaft furnace gases.…”