Isothermal reduction kinetics and mineral phase of chromium-bearing vanadium–titanium sinter reduced with CO gas at 873–1273 K

Abstract

Reduction of chromium-bearing vanadium–titanium sinter (CVTS) was studied under simulated conditions of a blast furnace, and thermodynamics and kinetics were theoretically analyzed. Reduction kinetics of CVTS at different temperatures was evaluated using a shrinking unreacted core model. The microstructure, mineral phase, and variation of the sinter during reduction were observed by X-ray diffraction, scanning electron microscopy, and metallographic microscopy. Results indicate that porosity of CVTS increased with temperature. Meanwhile, the reduction degree of the sinter improved with the reduction rate. Reduction of the sinter was controlled by a chemical reaction at the initial stage and inner diffusion at the final stage. Activation energies measured 29.22–99.69 kJ/mol. Phase transformations in CVTS reduction are as follows: Fe₂O₃→Fe₃O₄→FeO→Fe; Fe₂TiO₅→Fe₂TiO₄→FeTiO₃; FeO·V₂O₃→V₂O₃; FeO·Cr₂O₃→Cr₂O₃.

Keywords

sinter / kinetics / reduction / mineral phase

References

[1] Du H.G. Principle of Smelting Vanadium–Titanium Magnetite in the Blast Furnace, 1996, Beijing, Science Press 1.

[2] Liu J.X., Cheng G.J., Liu Z.G., Chu M.S., Xue X.X. Reduction process of pellet containing high chromic vanadium–titanium magnetite in cohesive zone. Steel Res. Int., 2015, 86(7): 808.

[3] Zhou M., Jiang T., Yang S.T., Ma K., Xue X.X., Zhang W.J. Optimization utilization of vanadium–titanium iron ore in sintering based on orthogonal method. Metalurgija, 2016, 55(4): 581.

[4] Yang S.T., Zhou M., Jiang T., Guan S.F., Zhang W.J., Xue X.X. Application of a water cooling treatment and its effect on coal-based reduction of high-chromium vanadium and titanium iron ore. Int. J. Miner. Metall. Mater., 2016, 23(12): 1353.

[5] Zhou M., Yang S.T., Jiang T., Xue X.X. Influence of MgO in form of magnesite on properties and mineralogy of high chromium, vanadium, titanium magnetite sinters. Ironmaking Steelmaking, 2015, 42(3): 217.

[6] Zhou M., Yang S.T., Jiang T., Xue X.X. Influence of basicity on high-chromium vanadium–titanium magnetite sinter properties, productivity, and mineralogy. JOM, 2015, 67(5): 1203.

[7] Zhou M., Jiang T., Yang S.T., Xue X.X. Sintering behaviors and consolidation mechanism of high-chromium vanadium and titanium magnetite fines. Int. J. Miner. Metall. Mater., 2015, 22(9): 917.

[8] Wang Y.M., Yuan Z.F., Matsuura H., Tsukihashi F. Reduction extraction kinetics of titania and iron from an ilmenite by H₂–Ar gas mixtures. ISIJ Int., 2009, 49(2): 164.

[9] Sun K., Takahashi R., Yagi J. Reduction kinetics of cement-bonded natural ilmenite pellets with hydrogen. ISIJ Int., 1992, 32(4): 496.

[10] Vries M.L.D., Grey I.E. Influence of pressure on the kinetics of synthetic ilmenite reduction in hydrogen. Metall. Mater. Trans. B, 2006, 37(2): 199.

[11] Zhao Y., Shadman F. Reduction of ilmenite with hydrogen. Ind. Eng. Chem. Res., 1991, 30(9): 2080.

[12] Vijay P.L., Venugopalan R., Amoorthy D.S. Preoxidation and hydrogen reduction of ilmenite in a fluidized bed reactor. Metall. Mater. Trans. B, 1996, 27(5): 731.

[13] Jones D.G. Kinetics of gaseous reduction of ilmenite. J. Chem. Technol. Biotechnol., 1975, 25(8): 561.

[14] Itoh S., Kikichi A. Reduction kinetics of natural ilmenite ore with carbon monoxide. Mater. Trans., 2001, 42(7): 1364.

[15] Zhao Y., Shadman F. Kinetics and mechanism of ilmenite reduction with carbon monoxide. AIChE J., 1990, 36(9): 1433.

[16] Zhang G.Q., Ostrovski O. Reduction of ilmenite concentrates by methane-containing gas: Part I. Effects of ilmenite composition, temperature and gas composition. Can. Metall. Q., 2001, 40(3): 317.

[17] Yang S.T., Zhou M., Jiang T., Wang Y.J., Xue X.X. Effect of basicity on sintering behavior of low-titanium vanadium–titanium magnetite. Trans. Nonferrous Met. Soc. China, 2015, 25(6): 2087.

[18] Zhou M., Yang S.T., Jiang T., Zhang L.H., Xiao J.T., Xue X., Zhang W.J. Effects of carbon content on the sintering behavior of low-titanium vanadium–titanium magnetite. Metall. Res. Technol., 2016, 113(6): 612.

[19] Zhao Y., Wu K., Pan W., Liu Q.H. Investigation of the reduction kinetics process of sinter ore by sectional stepwise method. J. Northeast. Univ. Nat. Sci., 2013, 34(9): 1282.

[20] Pan W., Wu K., Zhao X., Min D.J., Wang H.Y., Zhang Z.C. Reduction kinetics of Shougang iron ore sinter. J. Univ. Sci. Technol. Beijing, 2013, 35(1): 35.

[21] El-Geassy A.A. Influence of doping with CaO and/or MgO on stepwise reduction of pure hematite compacts. Ironmaking Steelmaking, 1999, 26(1): 41.

[22] El-Geassy A.A. Reduction of CaO and/or MgO-doped Fe₂O₃ compacts with carbon-monoxide at 1173–1473 K. ISIJ Int., 1996, 36(11): 1344.

[23] Nasr M.I., Omar A.A., Khedr M.H., El-Geassy A.A. Effect of nickel oxide doping on the kinetics and mechanism of iron oxide reduction. ISIJ Int., 1995, 35(9): 1043.