Selective extraction of vanadium from vanadium slag with blank roasting-sodium bicarbonate leaching process

In view of the problem of poor selectivity in clinker leaching and high impurity concentration in leaching solution with existing vanadium oxide extraction process from vanadium slag, a new process for vanadium extraction from vanadium slag by blank roasting and sodium bicarbonate leaching was proposed. The research mainly focused on the influences of roasting temperature, roasting time, particle size of vanadium slag, sodium bicarbonate concentration, leaching temperature, leaching time, particle size of clinker and liquid-solid ratios on leaching rate of vanadium. The phase and morphology changes of vanadium slag during the blank roasting and carbonation leaching process were analyzed with mineral liberation analyzer(MLA),scanning electron microscope(SEM) and energy disperse spectroscopy(EDS). The results show that during the blank roasting process of vanadium slag, vanadium mainly combines with calcium and manganese to form calcium-manganese pyrovanadate, which is distributed in a circular pattern at the edges of iron oxide and pseudobrookite. The leaching rate of vanadium is 94.03% when the roasting temperature is 930 ℃, roasting time is 120 min, concentration of NaHCO3 is 160 g/L, leaching temperature is 95 ℃, leaching time is 120 min and liquid-solid ratio (mL∶g) is 2∶1. The leaching solution contains V 38.83 g/L, Si 0.21 g/L, Fe 0.08 g/L, P 0.08 g/L, Ca 0.02 g/L, and Mn, Mg, Al, Cr＜0.01 g/L, which means low impurity concentration, realizing selective leaching of vanadium from clinker. The carbonation leaching solution has low concentrations of Ca, Mn, Mg, Fe, Al, P and Cr, and theoretically does not enrich, the wastewater after vanadium precipitation can be directly used for leaching clinker, eliminating wastewater treatment processes and avoiding the generation of solid waste in water treatment. © 2024 Central South University of Technology. All rights reserved.