Selective sulfuric acid cyclic leaching of vanadium from the calcification roasting pellets of vanadium titanomagnetite

Abstract

Here, a new method of sulfuric acid cyclic leaching was proposed to selectively leach vanadium from the calcification roasting pellets of vanadium titanomagnetite. Cyclic leaching and conventional heap leaching were compared. The results showed that under the optimal conditions, the leaching rate of vanadium was higher and those of iron and titanium were lower than when using conventional heap leaching. Under the optimal cyclic leaching conditions (acid concentration 3.0 mol/L, liquid: solid ratio 4: 1, temperature 90 °C, and leaching time 100 h), the leaching rate of vanadium reached 80.28%, while the leaching rates of iron and titanium were 1.39% and 1.72%, respectively. After secondary roasting, the crushing strength of the leached pellets reached 2200 N, which meets the requirements for pellets used in blast furnace smelting. In addition, the valence states of vanadium and iron in the pellets before and after leaching and the main phases in the pellets were analyzed and characterized. Most V5+ and Fe2+ leached, while Fe3+ was hardly leached, and main phases in the pellet were unchanged. Furthermore, the leaching kinetics of vanadium during cyclic leaching showed that the reaction rate of vanadium was controlled by solid product diffusion during acid leaching. In this study, vanadium was selectively leached, and iron was obtained by secondary roasting of the pellets, followed by blast furnace ironmaking. This paper provides a new method for the comprehensive utilization of valuable metals in vanadium titanomagnetite.