钙化提钒溶液沉钒的影响因素及沉钒动力学

用(NH4)2SO4对钒渣钙化焙烧、稀酸浸取、化学沉淀净化后的酸性含钒溶液进行沉淀富集，考察了钒浓度、初始pH值、加铵系数(NH3/V摩尔比)、沉钒温度和时间对沉钒率及V2O5含量的影响，研究了沉钒动力学，对沉钒产物进行了表征. 结果表明，在初始pH为2.00?0.05、加铵系数1.5、温度大于95℃、沉钒时间120 min、钒液中V浓度大于20 g/L的条件下，沉钒率超过96%，产品中V2O5含量大于98%，杂质含量符合98级氧化钒的国家标准. 75~99℃下的沉钒过程可由Avrami动力学方程描述，表观活化能Ea=93.23 kJ/mol，指前因子A=9.14×1011 min?1. 铵盐沉钒产物为(NH4)2V6O16?1.5H2O，高温煅烧所得V2O5晶体为柱状，平均粒径1.25 ?m，主要杂质Mn以MnV2O6形式存在.

Influence Factors and Kinetics of Vanadium Precipitation for the Vanadium Solution from Calcified Vanadium Extraction

Vanadium component was precipitated and concentrated by ammonium salt from the acidic vanadium solution obtained by the process comprising of calcium roasting, dilute acid leaching and chemical precipitation purification. The effects of concentration of vanadium, the initial pH of solution, adding amount of ammonium, temperature and time on precipitation rate and quality of vanadium pentoxide were studied and the kinetics of vanadium precipitation was analyzed. The precipitates were characterized. The results showed that under the conditions of initial pH of 2.00?0.05, molar ratio of NH3 to V being 1.5, temperature higher than 95℃, reaction time of 120 min and concentration of vanadium larger than 20 g/L, precipitation rate was higher than 96%, the content of V2O5 in the final product is over 98%, and the contents of impurities meet the standards of Grade 98 vanadiumpentoxide. Avrami kinetic equation well describes the precipitation process occurring at 75?99℃ with apparent activation energy Ea=93.23 kJ/mol and pre-exponential factor A=9.14×1011 min?1. The vanadium precipitate is (NH4)2V6O16?1.5H2O. The crystal of vanadium pentoxide exists in columnar with mean size of 1.25 ?m, and the main impurity of Mn appears as MnV2O6.