Mechanism of vanadic titanomagnetite solid-state reduction
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Rare Met. DOI 10.1007/s12598-014-0294-3
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Mechanism of vanadic titanomagnetite solid-state reduction Shui-Shi Liu, Yu-Feng Guo*, Guan-Zhou Qiu, Tao Jiang
Received: 30 July 2013 / Revised: 24 September 2013 / Accepted: 21 April 2014 Ó The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg 2014
Abstract The influence mechanism of vanadic titanomagnetite solid-state reduction was studied in this paper. Optical microscopy (OM), scanning electron microscope (SEM), and X-ray diffraction (XRD) were used to characterize the structure and phases of the samples. The results show that the dense structure is not the reason that limits the reducibility of Panxi vanadic titanomagnetite. Metallization rate of 93 % was achieved when it was reduced at 1100 °C for 100 min. After pre-oxidation, Fe9TiO15 and Fe2O3 are the main phases of samples. Pre-oxidation could destroy the dense structure of vanadic titanomagnetite and increase the specific surface area of particles. However, reducibility of vanadic titanomagnetite is not improved obviously by pre-oxidation, with metallization rate increasing only 1 % under the same reduction conditions, and the generated metallic iron grains are smaller. Phase transformation of vanadic titanomagnetite at different reduction temperatures shows that the presence of FeTi2O5 is the main reason that limits the reducibility of Panxi vanadic titanomagnetite. Keywords Vanadic titanomagnetite; Pre-oxidation; Solid-state reduction; Reduction process
1 Introduction Vanadic titanomagnetite is rich in Panxi area of China, with a reserve of nearly 10 billion tons [1–3], in which the reserves of Ti and V account for 34.79 % and 35.17 % of S.-S. Liu, Y.-F. Guo*, G.-Z. Qiu, T. Jiang School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China e-mail: [email protected]
the total reserves in the world, respectively [4–6]. The main way adopted to utilize these resources in China and Russia is traditionally named BF–BOF process, while in New Zealand and South Africa, prereduction-electric furnace process was industrialized. Those processes can only recover iron and vanadium, but titanium enriched in slag cannot be effectively used. In addition, BF–BOF is a complex process with high-energy consumption and environmental pollution [7–10]. With consideration of recovery valuable elements, various methods were researched, such as reduction-magnetic and sodium roasting reduction electric furnace [11–14]. The processes discussed above show that solid-state reduction of vanadic titanomagnetite is the key to utilizing vanadic titanomagnetite. However, owing to its complex structure, the reduction of vanadic titanomagnetite is more complicated than that of ordinary ore, which requires a higher temperature and longer time to achieve a high metallization rate. Therefore, it is noteworthy to study the influence mechanism of vanadic titanomagnetite solid-state reduction. The researches on solid-state reduction of the vanadic titanomagnetite
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