Innovative method for minimization of waste containing Fe, Mn and Ti during comprehensive utilization of vanadium slag

摘要

More than 1.2 million tons of tailings containing approximately 30 wt% of Fe from traditional vanadium extraction processes are discarded every year as solid waste, which waste resources. In order to achieve effective and green utilization of waste, a novel process was proposed to keep Cr and V at Cr~(3+) and V~(3+) during extraction by using AlG_3-NaCl-KCl molten salt in Ar gas atmosphere to control the valuable elements (Cr, V, Mn and Fe) from oxidized. The morphological features of vanadium slag reacted in the temperature range from 200 °C to 800 °C and volatilization of samples under different AlCl_3/slag ratios were analyzed. Meanwhile, the chlorinated kinetics of V, Cr, Mn and Fe in vanadium slag were systemically investigated in temperature range of 850 °C-950 °C. The kinetics investigation indicated that the chlori-nation processes of Fe and Mn were restricted by mass transfer in product layer (Al-Si-O mixture) and the chlorination processes of V and Cr were controlled by surface reaction. The apparent activation energies for Fe, Mn, V, and Cr are 105.28 kJ/mol, 94.26 kJ/mol, 64.64 kJ/mol, and 63.30 kJ/mol, respectively. After chlorination, the separation of metal chlorides was achieved. TiCl_4 is hydrolyzed to obtain TiO_2. Mn can be separated from VCl_3, CrCl_3, FeCl_2, and MnCl_2 by controlling the electrolytic voltages. Fe-V-Cr alloy was obtained by electrolysis at 2.3 V.