液相氧化法铬盐清洁工艺铬酸钠结晶分离应用基础研究
发布时间：2018-12-12 07:43
【摘要】：铬盐及铬系列化合物为重要的基础化工原料。针对传统有钙焙烧法铬盐生产工艺过程存在的资源利用率低和环境污染严重等问题，中国科学院过程工程研究所研发了具有我国自主知识产权的液相氧化法铬盐清洁生产工艺。中间产品铬酸钠的结晶相分离为该工艺的重要组成部分，其纯度和形貌将直接影响下游产品的质量和生产成本。本文选择了Na2CrO4-NaOH-NaAlO2-H2O体系，对铬酸钠结晶分离过程的相平衡、介稳区、动力学及工艺过程优化等问题进行了系统的应用基础研究。主要取得了以下创新性进展： 1)测定了Na2CrO4-NaOH-H2O三元体系在90℃、120℃和130℃时以及Na2CrO4-NaOH-NaAlO2-H2O四元体系在90℃、120℃和130℃时的相平衡数据，绘制了Na2CrO4-NaOH-H2O三元体系在90℃以及Na2CrO4-NaOH-NaAlO2-H2O四元体系在120℃和130℃的相图，为铬酸钠结晶分离提供了基础数据； 2)研究了铬酸钠在Na2CrO4-NaOH-H2O体系中的结晶介稳区以及杂质(NaAlO2)含量对介稳区宽度的影响，分别讨论了不同碱浓度下真空蒸发结晶过程中的压力与沸点的关系，同一溶液浓度体系下，真空度越高，，溶液的沸点越低，随着体系浓度的升高，沸点上升，所需真空度也升高； 3)采用间歇动态法研究了铬酸钠蒸发结晶过程动力学，用最小二乘法进行回归分析，得到了相应的结晶动力学方程，阐述了悬浮密度、搅拌速率、过饱和度和杂质对蒸发结晶过程的影响规律，随着悬浮密度、搅拌速率、过饱和度和杂质含量的增大均更有利于晶体的成核； 4)开展了铬酸钠蒸发结晶工艺优化研究，系统分析讨论了蒸发结晶过程中搅拌强度、蒸发速度、结晶温度、杂质含量、晶种添加对产品平均粒度及粒度分布、纯度和晶习的影响规律，确定出铬酸钠蒸发结晶的最优工艺条件为：搅拌速度为300r/min；蒸发速率约为150~200mL；结晶温度为90℃；杂质含量小于3g/L；添加晶种，在以上操作条件下可制备出粒度分布均匀，纯度可达97.5%以上的铬酸钠产品。
[Abstract]:Chromium salts and chromium series compounds are important basic chemical raw materials. In view of the problems of low resource utilization and serious environmental pollution in the traditional chromium salt production process with calcium roasting, the Institute of process Engineering of the Chinese Academy of Sciences has developed a clean production process of chromium salt by liquid oxidation with independent intellectual property rights in China. The crystallization phase separation of intermediate product sodium chromate is an important part of this process. Its purity and morphology will directly affect the quality and production cost of downstream products. In this paper, the phase equilibrium, metastable region, kinetics and process optimization of crystallization separation process of sodium chromate have been systematically studied in Na2CrO4-NaOH-NaAlO2-H2O system. The main achievements are as follows: 1) the phase equilibrium data of Na2CrO4-NaOH-H2O ternary system at 90 鈩
本文编号：2374205
[Abstract]:Chromium salts and chromium series compounds are important basic chemical raw materials. In view of the problems of low resource utilization and serious environmental pollution in the traditional chromium salt production process with calcium roasting, the Institute of process Engineering of the Chinese Academy of Sciences has developed a clean production process of chromium salt by liquid oxidation with independent intellectual property rights in China. The crystallization phase separation of intermediate product sodium chromate is an important part of this process. Its purity and morphology will directly affect the quality and production cost of downstream products. In this paper, the phase equilibrium, metastable region, kinetics and process optimization of crystallization separation process of sodium chromate have been systematically studied in Na2CrO4-NaOH-NaAlO2-H2O system. The main achievements are as follows: 1) the phase equilibrium data of Na2CrO4-NaOH-H2O ternary system at 90 鈩
本文编号：2374205
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