Research On Direct Vanadium Extraction By Calcium Roasting From Vanadium Titanium Magnetite Concentrate

The recovery of vanadium was lower and not higher than20%from vanadium slag originate from vanadium titanium magnetite. Tailings containing vanadium after water leaching is high in sodium content, which is unfit to follow-up disposal. At the same time, the filtrate containing some impurities after sodium roasting is difficult to obtain pure V2O5. In this paper, direct extraction of vanadium by calcium roasting from vanadium titanium magnetite concentrate is studied. This process is clean and cheap. Also, it can be in favour of utilization of resources.We can obtain some conclusions by mineral characterization of vanadium titanium magnetite concentrate. First, the concentrate is fine, which contains some grain finer than75micron accounting for43.17%, and it can be researched on ore dressing by grinding slightly. Second, the concentrate is mainly composed of O, Si, Nb, Zr, Ca, Ti, V, Fe and other elements. Third, the composition of concentrate under various sizes is similar. The concentrate is mainly composed of magnetite and ilmenite.The grinding efficient is high in the first30minutes. The suitable condition of anti-flotation desilication is:pH value6, particle size-400mesh, soluble starch200g/t, dodecylamine dosage900g/t. After anti-flotation, teh SiO2content is5.64%.We can obtain some conclusions by thermodynamic analysis and experiment of different conditions between vanadium titanium magnetite concentrate and calcium carbonate. First, the decomposition temperature of calcium carbonate is550℃,(FeO· V2O3) is oxidized when the temperature exceeds700℃. Second, there will be solid solution reaction in this roasting system, which causes restriction in the leaching of vanadium. So the recovery of vanadium is low. In order to reduce the impact of solid solution, we can make rapid cooling. Third, direct extraction of vanadium by calcium roasting from concentrate is better when the concentrate contains CaO, SiO2larger than2%,3%, respectively, and we selected CaCO3as toasting additive. Fourth, the suitable roasting condition is:CaCO3amount10%, toasting temperature1200℃, toasting time lh. And vanadium recovery rate can reach72.1%. Finally, it is in favour of conversion of vanadium that low partial pressure of oxygen in the roasting system.The suitable leaching condition is: H2SO4as the leaching agent is available. The optimum leaching process is liquid-solid5:1, H2SO4concentration5%, leaching time3h, leching temperature90℃, then the leaching rate of V2O5is71.4%.