Spent vanadium catalysts of sulfuric acid production (main elemental composition in wt%: 7.5 V, 9.1 K, 10.2 S, 23.2 Si and 1.4 Fe) can be used as a secondary source of vanadium. Extraction of vanadium was studied using two-step leaching (acidic and reductive) of spent vanadium catalysts with further oxidizing of leaching solutions. The factors leaching and hydrolysis temperature, concentration of leaching (H₂SO₄, Na₂SO₃) and oxidizing ((NH₄)₂S₂O₈) reagents, solid/liquid ratio, mixing parameters, and time of leaching and thermohydrolysis were systematically investigated. The solubility of V₂O₅ was investigated as a function of temperature, pH of sulfuric acid solutions, and concentration of Na₂SO₃. The kinetics of V₂O₅ solubility and reduction were also studied. The vanadium leaching yield after a two-step recovery was 98 wt% after acidic (H₂SO₄, pH 1.2–1.3) leaching with ultrasonic treatment for 5 min at ambient temperature, followed by reductive leaching in 0.01 Mol/L Na₂SO₃ solution for 15 min at ambient temperature. The highest vanadium extraction yield from leaching solutions was 98 wt% obtained through oxidizing of leaching solutions by 30 wt%. (NH₄)₂S₂O₈ with a molar ratio n(V₂O₅)/n((NH₄)₂S₂O₈) of 5/1 for a reaction time of 5 min at 80–90 °C. the extracted vanadium product was V₂O₅ with a purity of 85–87 wt%. The technological scheme has been developed to recycle all obtained products and sub-products

硫酸生产用过的钒催化剂（主要元素组成，以重量％计：7.5 V，9.1 K，10.2 S，23.2 Si和1.4 Fe）可用作钒的辅助来源。研究了钒的萃取过程，该过程使用了两步浸出的钒催化剂（酸性和还原性），并进一步氧化了浸出液。浸出和水解温度，浸出浓度（H ₂ SO ₄，Na ₂ SO ₃）和氧化性（（NH ₄）₂ S ₂ O ₈）试剂，固/液比，混合参数以及浸出和热水解时间的因素被系统地调查。V ₂ O ₅的溶解度根据温度，硫酸溶液的pH值和Na ₂ SO _3的浓度来研究碳氢化合物。还研究了V ₂ O ₅溶解和还原的动力学。酸性（H ₂ SO ₄，pH 1.2-1.3）在环境温度下超声浸提5分钟后，再进行0.01 Mol / L Na ₂ SO的还原浸提，经过两步回收后，钒的浸提产率为98 wt％。₃溶液在环境温度下放置15分钟。通过将浸出溶液氧化30重量％，从浸出溶液中最高的钒提取产率为98重量％。（NH ₄）₂ S₂ O ₈的摩尔比n（V ₂ O ₅）/ n（（NH ₄）₂ S ₂ O ₈）为5/1，在80–90°C下反应时间为5分钟。提取的钒产品为V ₂ O ₅，纯度为85-87 wt％。已经开发了技术方案以回收所有获得的产品和副产品