Na_2CrO_4-NaOH-H_2O体系中Na_2CrO_4真空蒸发结晶动力学研究  

Kinetics of vacuum evaporation crystallization of Na_2CrO_4 from Na_2CrO_4-NaOH-H_2O system

作　　者：刘欢[1,2,3] 田颖[1,2] 张小飞[4] 徐红彬[1,2] 张炳烛[3] 张懿[1,2] 

机构地区：[1]中国科学院过程工程研究所湿法冶金清洁生产技术国家工程实验室,北京100190 [2]中国科学院绿色过程与工程重点实验室,北京100190 [3]河北科技大学化学与制药工程学院,河北石家庄050018 [4]中国科学院苏州纳米技术与纳米仿生研究所印刷电子学部,江苏苏州215123

出　　处：《化学工程》2015年第2期35-39,共5页Chemical Engineering(China)

基　　金：国家自然科学基金资助项目(21406233);国家863计划项目(2011AA060702);973计划资助项目(2013CB632600)

摘　　要：在液相氧化法铬盐清洁生产工艺中,中间产品铬酸钠的结晶相分离为重要的组成部分,采用真空蒸发结晶的方法可从Na2CrO4-NaOH-H2O体系中分离得到铬酸钠晶体。文中研究了Na2CrO4在NaOH溶液中晶体成核与生长动力学规律。采用间歇动态法中的矩量变换法建立了结晶过程的动力学模型,用最小二乘法对动力学实验数据进行多元线性回归,得到了动力学参数,并验证了动力学模型的可靠性。结果表明:在粒度大于50μm的范围内,铬酸钠晶体的生长符合粒度无关生长模型;晶浆的悬浮密度、搅拌强度和过饱和度对成核速率均有显著影响;溶液过饱和度对成核速率的影响大于对生长速率的影响。结晶动力学的研究为液相氧化法铬盐清洁生产工艺中铬酸钠和氢氧化钠的分离工艺优化提供了理论基础。In the chromate production technology through alkali leaching of chromite ore,the crystallization and phase separation of Na2CrO4is an important part of this process. The vacuum evaporation crystallization was employed to separate Na2CrO4from the Na2CrO4-Na OH-H2O system. The crystal nucleation and growth kinetics of Na2CrO4in Na OH solution was investigated. The intermittent dynamic method was adopted to establish the kinetic model for the crystallization process. The kinetic parameters were obtained by using least square method for the multivariate linear regression,and the reliability of the kinetic model was also validated. The results show that the growth of sodium chromate obeys the size-independent growth model while the particle size is larger than 50 μm;the suspension density,mixing intensity and supersaturation have significant effects on the nucleation rate; the supersaturation has a greater effect on nucleation rate than on growth rate. This study of the crystal nucleation and growth kinetics can be a good foundation for the optimization of separating crystallization process between Na2CrO4and Na OH in the chromate production technology through alkali leaching of chromite ore.

关 键 词：铬酸钠 氢氧化钠 真空蒸发结晶 结晶动力学 间歇动态法 

分 类 号：TQ131.12[化学工程—无机化工]