China Nonferrous Metallurgy

The separation and purification of vanadium from vanadium-containing solutions is the key to preparing high-purity vanadium. Conventional extraction and purification require a large amount of reagents, generate a large amount of wastewater, have high requirements for the acid resistance of equipment, and have poor ion selectivity. The pH value of Cyanex272 extraction is mainly between 2.5 and 4.0, which has a relatively low requirement for the acid resistance of the equipment. Moreover, the wastewater generated during extraction causes less harm to the environment. In this paper, the vanadium solution after calcification roasting and acid leaching of vanadium slag from a certain enterprise was used as the raw material. Cyanex272 was used as the extractant and sulfuric acid as the stripping agent to purify vanadium and prepare V₂O₅ The extraction mechanism of Cyanex272 was explored through characterization analysis, and the following main conclusions were obtained. Cyanex272 exhibits excellent selectivity for V(Ⅳ) under acidic conditions. Under the conditions of organic phase composition of Cyanex272∶TBP∶sulfonated kerosene=4∶0.5∶5.5, solution pH=3.0, extraction time 10min, extraction temperature 30℃, and O/A ratio of 1∶1, The vanadium extraction rate of single-stage extraction was 78.06%, and that of three-stage extraction reached 98.80%. Under the conditions of A sulfuric acid concentration of 3.0mol/L as the stripping agent, a stripping time of 6min, a stripping temperature of 30℃, and a stripping ratio of O/A=1∶1, the vanadium stripping rate of single-stage stripping was 80.70%, that of three-stage stripping reached 98.38%, and the purity of V₂O₅ after calcination was 99.36%. The vanadium reduced by sodium sulfite in the vanadium solution mainly exists in the form of VO²⁺. The phosphate group of Cyanex272 undergoes chelation reaction with VO²⁺ by breaking the P—O—H bond to form a stable metal complex, thereby achieving the separation and extraction of vanadium ions.