| Vanadium and titanium resources is aboundant in China and the majority is in Panzhihua-Xichuang. The main resource of the region is vanadium-bearing titanomagnetite containing more than20kinds of rare metals such as V, Ti, Fe, Cr, Ni, Co, etc. Determined by characteristics of the resource, titanium was distributed into the iron ore concentrate after beneficiation process. As the use of steel-oriented technology via traditional BF-BOF smelting, titanium in iron concentrate eventually turns into the blast furnace slag (the content of TiO2is about25%) in the form of TiO2after consuming large amounts of energy, resulting in lower utilization of titanium resources. Titanium-enriched material with high quality is a strong guarantee for titanium industry to reduce the environmental pressures of the titanium dioxide industry, for our country to comprehensively improve the overall level of titanium dioxide and titanium industry. In this research, three kinds of typical domestic titanium resources were used as raw material.The mineral phase composition and impurity separation mechanism were investigated in detail via hydrometallurgical method to upgrade titanium-enriched slag, improve the resource utilization of vanadium-bearing titanomagnetite and provide a new process for upgrading of titanium slag industry. The main contents are listed as follows:(1) Titanium slag (the content of TiO2is52.54%) produced by coal-based DR-EAF smelting process was used in the research and enriched by phosphoric acid activation-acid leaching coupling method. Phase compositions of the titanium slag such as anosovite, pyroxene (glass), taki stone and spinel were analyzed with MLA (Liberation analysis of minerals). The impact of crystal form transforming and the leaching ratios of the main impurities such as Ca, Mg, Al and Si were investigated in the experiment under different conditions. XRD analysis results showed that the anosovite phase in the slag was completely destroyed, while magnesia-alumina spinel was retained. Under the optimal conditions, the content of TiO2in the slag was increased to68.31%.(2) Low-grade (the content of TiO2is45.01%and V2O5is1.22%), high reaction activity V-Ti slag was obtained from vanadium-bearing titanomagnetite concentrate via selective reduction-magnetic separation. The main phases of the slag are anosovite and pyroxene. Two-stage acid leaching was employed to remove the impurities in the slag. The leaching behavior of impurities Ca/Mg/Al/Si under different acid leaching conditions in the first stage was investigated in detail. Under the optimal conditions of the first-stage, the leaching resdue obtained contained79.54%of TiO2and2.50%of V2O5, respectively. Then, the anosovite structure was destroyed via leaching with a higher concentration of HCl under oxygen pressure. The impurities were further leached out, and rutile Ti-enriched slag with TiO2content of83.86%was obtained. V and Ti were separated efficiently in this stage and the content of V2O5in the rutile Ti-enriched slag is0.18%. The leaching solution can be used as a raw material for V extraction and the solid residue can be used as raw material in the chloride process to prepare TiO2pigment after the removal of residual carbon. The molecular structure simulation results indicate that the Ti-O and Mg-O bonds in the anosovite phase are broken under oxygen pressure conditions in the second stage by reacted with HCl solution. The content of TiO2in the rutile Ti-enriched slag prepared by two-stage acid leaching can reach92.5%with further removal of residual carbon.(3) Vanadium-bearing titanomagnetite concentrate from western part of Liaoning Province is one kind of typical resources with low grade of iron and high grade of vanadium and titanium, and the concentrate contained TiO2, V2O5, TFe are24.83%,0.95%and35.53%, respectively. Ti, V, Fe were associated closely. Fe in the concentrate mainly exists as the form of magnetic iron and ilmenite, which has highly reactivity in hydrochloric acid leaching process. The V, Fe were leached out by treating vanadium-bearing titanomagnetite concentrate with higher concentration of hydrochloric acid under atmospheric condition. The leachate with high concentration of V, Fe contained3.72g/L of V and116g/L of Fe, respectively, which were used for the subsequent extraction of vanadium and iron. However, the rutile Ti-enriched slag obtained contains TiO2of63.88%, and could be used as the raw materials to produce titanium dioxide. |
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