Effect of Preformed Calcium Ferrite Addition on Sintering Behavior of Vanadium Titanium Magnetite Ore
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https://doi.org/10.1007/s11837-020-04476-y Ó 2020 The Minerals, Metals & Materials Society
SINTERING OF OXIDES AND CONCENTRATES
Effect of Preformed Calcium Ferrite Addition on Sintering Behavior of Vanadium Titanium Magnetite Ore GANG LI,1,2 XUEWEI LV,1,2,3 ZHUANG ZHENG,1,2 JIAWEI LING,1,2 and GUIBAO QIU1,2 1.—College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China. 2.—Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials, Chongqing University, Chongqing 400044, China. 3.—e-mail: [email protected]
A new approach is proposed to improve the strength of the vanadium titanium magnetite (VTM) sinter by adding preformed calcium ferrite (CF) to partially substitute the CaO. The effects of the sintering temperature, oxygen partial pressure (pO2), heating time, and substitution ratio of preformed CF on the mineralogy of the VTM sinter are examined through tablet sintering. The results indicate that sintering temperature significantly affects the matrix structure and pore morphology by influencing solid–liquid assimilation and bubble coalescence. With an increase in pO2, the generation of calcium ferrites and hematite is favored, and the matrix transforms into a melting corrosion structure. Heating time mainly affects the pore shape. The addition of preformed CF to VTM sintering can not only inhibit the generation of perovskite and promote the formation of calcium ferrites but also increase the quantity of melts and promote solid–liquid assimilation.
INTRODUCTION Vanadium titanium magnetite ore (VTM) is an important complex mineral resource with a high comprehensive utilization value. Its proven reserves in the Panxi district, China, are 9660 million tons and account for more than 90% of the Ti reserves in China. VTM is an Fe3-xTixO4 solid solution between magnetite (Fe3O4) and ulvospinel (2FeOÆTiO2), with impurities such as aluminum, vanadium, and magnesium occurring as solid solution components within the lattice.1,2 Thus far, VTM has mainly been used as a material in the blast furnace–basic oxygen furnace process. In this process, most iron and some vanadium are reduced to hot metal and further treated to recover iron and vanadium, whereas Ti is almost entirely not reduced and concentrated into the blast furnace slag.2,3 Generally, the normal iron ore sinter is composed of ironbearing minerals (40–70 vol.% hematite, Fe2O3, and magnetite, Fe3O4), Ca-rich ferrites (20–50 vol.% calcium ferrites), glasses (quenched melt), and calcium silicates (each up to 10 vol.%).4,5 However, (Received July 31, 2020; accepted October 27, 2020)
for the sintering process with a certain mass ratio of VTM, the perovskite (CaTiO3) phase is usually generated though reaction between CaO and TiO2, and CaTiO3 is thought to have a negative effect on the sinter quality.6–8 Extensive reports on the addition of VTM to the sintering process indicate that a high TiO2 content may deteriorate the metallurgical properties, such as the cold strength, productivity, melting–dripping characteristics, a
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