| Hongge V-Ti magnetite is a polymetallic deposit associated with vanadium, chromium, iron and titanium resources. As the existing technology can not meet the demand of fully extract various valuable elements, the sourth mining area of Hongge has been in the limited exploitation. Relying on the two step process to extract vanadium, chromium can be oxidized into slag and then separate it from vanadium containing solution in the hydrometallurgical process of vanadium extraction.This methold could reach the target of recovery vanadium and chromium simultaneously. At present, there are few studies on the physicochemical properties of vanadium with high chromium content(vanadium-chromium slag), the basic theory of recovery of vanadium and chromium is in urgent need of deeply study.Present work takes the Fe Ox-Si O2-MnO-Ti O2-VOx-Cr Ox-MgO slag system as the main object of study. The main valences of vanadium, chromium and ferrum in vanadium-chromium slag and the influencing factor are studied by a thermodynamic model and X-ray photoelectron spectroscopy(XPS) analysis method. The calculated result shows that the main valences of vanadium is +3, +4, while chromium, ferrum are +3 and +2 in slag, respectively. The XPS result shows that the main valences of vanadium are +3, +5 and ferrum are +2, +3, while the chromium is +3. In this study, the oxgen potential has most obvious effect on the valences. With the increase of oxge n potential, the valences of vanadium, chromium and ferrum are increasing, while the valences do not change obviously with the variation of the content of V2O3 and Cr2O3. The oxgen poentail(2log()OP) at the industrial vanadium extraction condition is in the range from-13 to-10 atm. In this case, the main valence of vanadium is +3, and secondly is +5; the main valence of ferrum is +2 and then is +3; the mai n valence of chromium is +3 in vanadium-chromium slag.In order to study the distribution behaviors of vanadium and chromium between slag and hot metal, an ions and molecule coexist theory thermodynamic model was establilsed. At the same time, an indirect equilibrium experiment between vanadium-chromium slag and solid iron was adopted to avoid the influence of carbon in hot metal. Both experiemts and calculations present that the LCr and LV are increasing with the increase of w(FeO) while decrasing with the increase of w(Si O2). The increase of w(V2O3) and w(Cr2O3) lead to LV and LCr increasing respectively.The LCr and LV are kepted in higher values while the tempereature not higher than 1653 K. The values of log(LCr) and log(LV) are in the range from 2 to 3.2. Therefore, to maximize the values of LCr, LV in the process of extrating vanadium and chromium, the slag should has the properties of high oxidizing property, low Si O2 content and the reasonable content of V2O3 in the range of 9%~11% and Cr2O3 in the range of 5%~6%. Besides that, the temperature of oxidation reavtion should be controlled below 1653 K. |
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