Vanadium Extraction from Refractory Stone Coal Using a Streamlined Process

Based on the properties and petrographic analysis of a refractory stone coal from Hubei province,a novel vanadium extraction process of fluidized roasting-acid leaching with additive-solvent extraction-precipitation was proposed.The effects of roasting temperature,roasting time,dosage of additives,sulfuric acid concentration,liquid to solid ratio,leaching temperature and time on leaching ratio of vanadium were given a special concern.Results show that under the optimum conditions of roasting at 750 ℃ for 20 min,leaching additive dosage of 5%,sulfuric acid concentration of 15%,liquid to solid ratio of 2 ∶ 1 and leaching at 95 ℃ for 6 h,vanadium leaching efficiency can reach 91.32%.Using N235 as extractant,more than 98% of vanadium can be separated and concentrated from the leaching solution by three stages of counter-current extraction and three stages of counter-current stripping. Ammonium metavanadate can be precipitated from the vanadium concentrated solution after impurities removal,and then vanadium pentoxide with purity of 99.75% could be obtained after thermal decomposition of metavanadate. This vanadium extraction process has advantages of short procedure,high efficiency and high purity of product,showing well adaptability to refractory stone coal.