High-efficient extraction of vanadium and its application in the utilization of the chromium-bearing vanadium slag

•Efficient extraction of vanadium using primary amine with hydrogen bond association mechanism.•The impurity ions containing in the leaching solution was also considered.•The extractant natures including viscosity and the dissolution loss were researched.•The industrial experiments were performed based on the lab and pilot work.•The vanadium was recycled as a high value product to be 99.5 wt.% vanadium pentoxide.

The high-efficient extraction of vanadium using primary amine and its application in the utilization of the chromium-bearing vanadium slag (V–Cr slag) were studied in this work. The extraction mechanism and the possible difficulties in the application were both considered. From the results, the extraction percentage of vanadium using free primary amine with the hydrogen bond association mechanism is higher than that in the acidic environment by primary amine salts. The inorganic ions and other impurities existing in the system were all considered to research for the continuous operation of the extraction. Furthermore, the viscosities of the fresh organic phase and the recycled organic phase were determined using the extractant not only N1923 but also LK-N21, where the viscosity of the latter system increased slightly during the recycled process of the extractant. Based on the above results, the pilot and the commercial experiment were carried out. In the large-scale experiment, the vanadium was extracted and the product of 99.5 wt.% vanadium pentoxide was obtained, and the mass loss of the extractant was only 0.1%.