Leaching rate improvement of vanadium by high-carbon stone coal fluidized through oxidizing roasting

In order to enhance the leaching rate of vanadium,the fluidized oxidizing roasting was adopted to pretreat the high-carbon stone coal from Guangxi province,China.The thermodynamics of oxidizing roasting process and the oxidation kinetics of vanadium were analyzed,and the effect of fluidized roasting conditions on leaching rate of vanadium was investigated.The results indicate that the oxidation reaction of carbon and pyrite occurs more easily than that of V(Ⅲ) during the roasting process.Therefore,the vanadium oxidation reaction is inhibited by the existence of carbon and pyrite.The vanadium oxidation reaction is controlled by diffusion kinetics and the apparent activation energy is 347.00 kJ /mol.As the roasting temperature increases,the leaching rate of vanadium firstly increases and then decreases.Under roasting temperatures of 700 ℃ and 750 ℃,the leaching rate increases with the extension of roasting time.The leaching rate of vanadium reaches its maximum value(97.51%) under the roasting conditions of 800 ℃ and 0.5 h,the extension of roasting time(0.5 h) was not favorable for vanadium leaching.Compared with the traditional salt roasting method,the technique has the characteristics of high leaching rate and more environment safety.