Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5480803 | Journal of Cleaner Production | 2017 | 11 Pages |
Abstract
The traditional industrial practice for extracting vanadium from vanadium slag involves a Na2CO3-Na2SO4-NaCl-added pellet roasting at 800 °C followed by a water leaching. Some chlorine and hydrogen chloride are emitted by this process. About 80% of vanadium and 5% of chromium can be extracted in this case. The disposal of this leaching residue containing high contents of chromium and vanadium is still an unsolved environmental problem so far. A complete extraction of vanadium and chromium from vanadium slag might be an ultimate solution. In order to efficiently extract vanadium from vanadium slag, an innovative NaOH-added pellet was applied in this work to replace traditional Na2CO3-Na2SO4-NaCl-added pellet. It was found that the volume of NaOH-added pellet increased by 144% and many cavities were formed spontaneously throughout the pellet during the roasting at 700 °C. A solid phase (dry slag minerals), a liquid phase (molten liquid drops of NaOH with low viscosity) and a gas phase (O2) were involved in a three-phase reaction occurred inside the pellet. The spontaneously formed cavities created good kinetic conditions for the three-phase reaction. The V extraction was thus increased from traditional 80% at 800 °C to current 99% at 700 °C. The V extraction was increased by 39% when a NaOH-added pellet sample was used instead of a NaOH-added powder sample. The roles of porous pellet and liquid NaOH drops were explored. The V extraction dramatically increased with increasing temperature in the temperature range of 400 °C to 600 °C and reached a maximum at 700 °C. The V extraction dramatically increased with time within the first 15 min at 700 °C. The optimal roasting temperature, time and R(Na/Cr) value for the V extraction were 700 °C, 15 min and 7.67, respectively. The V extraction was 99.2% under the optimal conditions. The cooling rate of the roasted pellet had no significant effect on V extraction. The vanadium from the vanadium slag was mainly contained in a vanadium-containing spinel phase (Mn, Fe)(V, Cr, Ti)2O4. The oxidation of V3+ probably went through the following process: (Mn, Fe)(V, Cr, Ti)2O4 â(Cr0.15V0.85)2O3âNaVO2âNa3VO4. This process avoided the emission of toxic gas.
Keywords
Related Topics
Physical Sciences and Engineering
Energy
Renewable Energy, Sustainability and the Environment
Authors
Yilong Ji, Shaobo Shen, Jianhua Liu, Yuan Xue,