Na_2CrO_4-NaOH-H_2O体系中Na_2CrO_4蒸发结晶工艺研究  

Evaporation crystallization of Na_2CrO_4 from Na_2CrO_4-NaOH-H_2O system

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

机构地区：[1]河北科技大学化学与制药工程学院,河北石家庄050018 [2]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 [3]中国科学院绿色过程与工程重点实验室

出　　处：《无机盐工业》2014年第5期19-22,34,共5页Inorganic Chemicals Industry

基　　金：国家自然科学基金(21206178);863计划(2011AA060702);973计划(2013CB632600)资助项目

摘　　要：以90℃的Na2CrO4-NaOH-H2O体系相图为依据,采用蒸发盐析结晶的方法从体系中分离铬酸钠晶体,研究了搅拌强度、蒸发速度、结晶温度、晶种添加等因素对工艺过程的影响规律,得到最优工艺操作条件:搅拌强度为能使晶体离底悬浮所需的最小转速;每1 050 g原料的蒸发速率约为140 mL/h;结晶温度为90℃;并添加一定量的晶种。在以上操作条件下制备出的铬酸钠晶体粒度较大,尺寸均一。同时研究了不同氢氧化钠浓度下体系压力与沸点间的关系,为铬酸钠结晶过程的温度控制提供了基础数据。Vacuum evaporation crystallization to prepare sodium chromate crystal on the basis of the phase diagram of Na2CrO4-NaOH-H20 system at 90℃ was introduced.The effects of the crystallization conditions, including stirring intensity, evaporation rate, crystallization temperature, and seed addition etc., on the process were studied.The optimized operating conditions were determined as follow：the minimum stirring speed to make the crystals suspended from the bottom,the evaporation rate of about 140 mL/h per 1 050 g of raw material, the crystallization medium temperature of 90℃, and a certain amount of Na2CrO~ crystal added as the crystallization seeds.Na2CrO4 crystals with large and uniform particle size were prepared under the above optimum conditions.Moreover,the relationship between the boiling point and vapor pressure of the aqueous system with different NaOH concentrations was also investigated, providing a basis for the temperature control during the crystallization process.

关 键 词：铬酸钠 蒸发结晶 盐析 相图 沸点 

分 类 号：TQ131.12[化学工程—无机化工]