Selective extraction of vanadium from pre-oxidized vanadium slag by carbochlorination in fluidized bed reactor

Most of the vanadium (V) is industrially extracted from vanadium slag, a byproduct in steelmaking, via the sodium roasting-water leaching or calcification roasting-acid leaching process, which usually suffers from environment pollution or decrease in product purity. In this paper, a novel process of vanadium extraction featuring carbochlorination of pre-oxidized vanadium slag with chlorine (Cl-2) and nitrogen (N-2) mixture in a fluidized bed reactor was proposed. And the selectivity between vanadium and iron (Fe) in the slag was primarily concerned, due to the high content of the latter in vanadium slag. The thermodynamic analysis reveals that there exists a favorable zone for selective chlorination of V from Fe compounds. Subsequently, carbochlorination experiments were conducted to investigate the influences of chlorination temperature and time, addition amount of petroleum coke and pressure fraction of chlorine on extraction of V and Fe. And 87.47% of V together with 18.79% of Fe can be extracted from the pre-oxidized vanadium slag by chlorination at 650 degrees C for 120 min with chlorine pressure fraction [P(Cl-2)/ P(Cl-2+N-2)] = 0.5 and petroleum coke mass fraction in raw materials for chlorination Rc = 10%. The results demonstrate that the selective chlorination process has good potential to recover vanadium from vanadium slags in efficient and clean ways. (C) 2019 Elsevier Ltd. All rights reserved.