Abstract:Vanadium extraction from stone-coal was investigated by oxygen pressure acid leaching and solvent extraction. The mineralogy of the stone-coal from Tongren City of Guizhou Province, China, was investigated by various determination methods. The effects of leaching time, leaching temperature, leaching agent concentration, leaching L/S ratio, granularity of material, additive consumption were investigated based on the mineralogy. The results show that under the conditions of leaching time of 3−4 h, temperature of 150 ℃, sulfuric acid consumption of 25%−30%, ratio of liquid to solid of 1.2:1, the granularity less than 0.074 mm, additive consumption of 3%−5%, and oxygen pressure of 1.2 MPa, and the vanadium leaching rate can be more than 92% by the method of two-step pressurized acid leaching. The powdery V₂O₅ product with 99.52% in V₂O₅ content is obtained by the flowsheet of acid recovery, removing iron by reduction process, solvent extraction, precipitating vanadium with ammonium water, and pyrolysis from the stone-coal oxygen pressure acid-leaching solution. The total recovery efficiency of vanadium is above 85%, which is more than 20% higher than that obtained in the conventional process. Furthermore, the new process does not cause air pollution since no HCl or Cl₂ is released by calcination of the raw material.

Key words: stone-coal; extracting vanadium; oxygen pressure; acid leaching; acid recovery; solvent extraction