Separation of Anosovite from Modified Titanium-Bearing Slag Melt in a Reducing Atmosphere by Supergravity
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m (Ti)-bearing blast furnace slag containing 20 to 25 wt pct TiO2 was a main byproduct of blast furnace ironmaking using vanadium–titanium magnetite as raw material.[1] However, the beneficiation methods currently face great difficulties in separating the Ti from this kind of secondary resource for its complicated mineralogy and very fine mineral dissemination; thus, the Ti-bearing slag has been accumulating 70 million tons at a rate of 3 million tons annually in China.[2] So far, many technical routes have been proposed for recovering Ti from the slag, including acid leaching,[3] alkaline decomposing,[4] high-temperature carbonization, and low-temperature chlorination.[5] Moreover, the precipitation method[6] was proposed for recovering Ti-bearing minerals from the slag, while the vast majority of investigations were aimed at the perovskite due to its similar compositions as the blast furnace slag and its easy accessibility.[7,8] Considering the fact that the theoretical content of Ti in the anosovite (Ti3O5) was much higher than that in the perovskite (CaTiO3) and YANG LU, JINTAO GAO, FUQIANG WANG, and ZHANCHENG GUO are with the State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, P.R. China. Contact email: [email protected] and zcguo@ustb. edu.cn Manuscript submitted August 23, 2016. Article published online December 5, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS B
factoring in its greater density, the anosovite would be a better choice for separating Ti from the Ti-bearing slag. Li et al.[9] proposed that anosovite appeared in the Ti-bearing slag in the case of increasing the SiO2 content to above 35 wt pct and reducing it at a high temperature, whereas it was difficult to separate the crisp precipitates from the slag by conventional mineral processing.[10] Zhong et al. suggested a phosphoric roasting and leaching process for separating the Ti in a rutile state from the slag.[11] Hence, under the inspiration of the successful application of supergravity on some other melts,[12–15] separation of the anosovite from the modified Ti-bearing slag melt after precipitation in a reducing atmosphere by supergravity was investigated in the current study. Simultaneously, the effects of the gravity coefficient and slag composition on the microstructures, the mineral compositions, the purity, and the recovery ratio of Ti in the separated anosovite were investigated further. The simulated slag was prepared by mixing chemical agent powders based on the compositions of Ti-bearing blast furnace slag from Panzhihua Iron and Steel Corporation of China (Panzhihua, Sichuan, China), as shown in Table I, and the mass fraction of SiO2 was increased to 40 wt pct for promoting the formation of anosovite according to the experiments conducted by Li et al.[9] Furthermore, with respect to the thermodynamic data of reduction and the precipitation reactions of Ti oxide, increasing the Ti content while decreasing the calcium content could facilitate the reduction of high valence state Ti;[9,16
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