High-Efficiency Stepped Separation and Recoveries of Vanadium and Molybdenum via Low-Temperature Carbonation Conversion of High-Chromium Vanadium Residue

Abstract

High-chromium vanadium residue (HCVR (HCVR: high-chromium vanadium residue)) is an important secondary resource of valuable metals such as vanadium (V), chromium (Cr), and molybdenum (Mo). The mainstream technology for the utilization of HCVR, the Na2CO3-assisted-roasting–water-leaching method, usually requires roasting temperatures of more than 800 °C and results in the synchronous leaching of Cr with V and Mo. This makes the subsequent separation of V, Mo, and Cr in the aqueous system difficult. In this study, an efficient and clean process for the selective separation of Cr and stepped recoveries of V and Mo from HCVR is proposed via K2CO3-mediated carbonation conversion. Using this process, the roasting temperature can be reduced from more than 800 °C to 200 °C, and 83.14%, 99.94%, and 0.33% of V, Mo, and Cr, respectively, can be leached. Further, using the weakly alkaline ammonium-salt and sulfide precipitation methods, 98.28% pure V2O5 and 98.65% pure MoS2 can be obtained and the recoveries of V and Mo can reach 82.47% and 98.88%, respectively. While almost all Mo can be recovered from the HCVR, Cr and some V might be present as a stable ferrochrome spinel in the tailing, which may be returned to the main process for the extraction of V and Cr from vanadium slag. Thus, K2CO3 might be a more effective alternative to Na2CO3 for the separation and recovery of V and Mo from HCVR and, hence, may enable its more efficient utilization.