Extraction of vanadium from black shale by novel two-step fluidized roasting process

A novel two-step fluidized roasting (TSFR) process was explored to promote vanadium extraction from black shale. The phase transformation, micromorphology, and pore structure during the conditional experiment were investigated by XRD, FTIR, SEM-EDS, and BET. The results showed the optimal conditions of first-step roasting were 650 degrees C, 60 min, and 30% O2, and second-step roasting was 950 degrees C, 75 min, and 21% O2. The vanadium leaching rate (TSFR) reached 68.54% which increased by 39.28% than raw ore and 13.54% than original NaCl roasting. Furthermore, 95.89% carbon was removed in first-step roasting. It avoided the spontaneous combustion and sintering of black shale when it was directly roasted at high temperature. Dolomite and kaolinite were decomposed. Second-step roasting made V-bearing sericite dehydroxylation. This destroyed the sericite lattice and promoted the release of V3+. Therefore, this study is expected to have guiding significance for the efficient and green development of vanadium extraction.