An environmentally-friendly technology of vanadium extraction from stone coal

A novel technology characterized by higher recovery of vanadium and which was environmentally-friendly was developed to recover vanadium from stone coal. Vanadium in stone coal could be leached by NaOH solution after roasting stone coal at 850 °C for 3 h. H2SO4, Mg(NO3)2 and ammonia were employed, respectively, in two steps to remove the impurities of Si and Al from the leach liquor. After extracting vanadium from the leach liquor with 10 vol% N235, 20 vol% secondary octyl alcohol and 70 vol% sulfonated kerosene, 1.5 mol/L NaOH was used as a stripping agent to strip vanadium from extracting solution. Adding 80 g/L NH4NO3 to the stripping solution at 30–40 °C and pH 7.5, vanadium could be crystallized as ammonium metavanadate. Roasting ammonium metavanadate at 540 °C for 1 h, the purity of V2O5 met the standard specification. The total recovery of vanadium reached 67.39%, which was higher than the classical technology.