Crystallization Rate and Purity of Produced Crystals

结晶率和所产生晶体的纯度

• 批准号: 05650770
• 负责人: TOYOKURA Ken
• 金额: $ 1.47万
• 依托单位: Waseda University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05650770/
• 关键词: Melt Cry.; Crystal Purity; Secondary Nucleation; Agglomeration and Attachment of fines; Benzene-Cyclohexane; p-xylene-cyclohexane; Semi-batch Crystallize; Inclusion of Mother Liquor; p-キシレン-シクロヘキサン

In industrial crystallization, high purity substance is needed through purification and separation process with saving energy. Concerning separation from cutectic melt, mother melt happens to be included on the surface of crystals, to make the purity lower, and so sweating operation has been selected to improve the purity. In this study, correlation between basic crystallization phenomena and crystal purity wereinvestigated focusing nucleation and growth phenomena, to aim to propose the new theory on the mother inclusion in the process of crystallization, and optimum condition for high purification performance. In this study for the cutectic system of benzene and cyclohexane, experiments of benzene crystallization were performed using semi batch apparatus, to measure the time course of particle size distributions (PSD) and purity of crystals in the determined size range. From the time course of PSD,crystal growth was recognized to proceed by the mechanism of uniting primary nuclei wach … More other and attaching them, and secondary nuclei were observed to be produced periodically. And also crystal purity after wiping operation, was correlated quantitatively with crystal size, to make clear that there are three stages in which (1) formation of small crystals including much mother melt by the agglomeration mechanism of fineparticles, (2) formation of middle sizeone having low content of mother melt : in which find particles are thought to be incorporated into the large crystal, (3) formation of large crystals, in which mother melt are kept between the fine crystals attached to the surface of large crystal. And also batch experiments were performed in the cutectic system of paraxylene and cyclohexane. By the result, initial primary nucleation phenomena affected the purity, and also the mechanism of impurity discharge was shown by our model, considering crystal growth phenomena in the equipment. Based on the result described above, the mechanism and kinetics of impurity inclusion and discharge were considered to propose the optimum crystallization operatin condition for high purification. Less

在工业结晶中，需要通过提纯分离过程获得高纯度的物质，同时又节约能源。在与直熔体分离时，由于晶体表面恰好含有母熔体，使得纯度较低，因此选择了发汗操作来提高纯度。本研究主要研究了碱性结晶现象与晶体纯度的关系，重点研究了结晶成核和生长现象，旨在提出结晶过程中母体包裹体的新理论，以及获得高纯化性能的最佳条件。本研究以苯和环己烷的共晶体系为对象，采用半间歇装置进行了苯结晶实验，测定了在确定的粒径范围内，苯结晶的粒径分布（PSD）和纯度的时间过程。从PSD的时间过程来看，晶体的生长是由初核相互结合、相互附着的机制进行的，并观察到次生核的周期性产生。并将擦拭后的晶体纯度与晶体尺寸进行定量关联，明确了通过细颗粒的团聚机制形成含大量母熔体的小晶体和含少量母熔体的中等大小晶体的三个阶段。(3)形成大晶体，其中母体熔体保持在细小晶体之间，附着在大晶体表面。并在对二甲苯和环己烷的共渗体系中进行了批量实验。结果表明，初始初成核现象影响了杂质的纯度，并考虑了设备中晶体生长现象，通过模型揭示了杂质放电的机理。在此基础上，分析了杂质夹杂和排出的机理和动力学，提出了高纯度的最佳结晶操作条件。少

项目成果

Ken Toyokura, Izumi Hirasawa: "Crystallization from the Melt" Crystallization Technology Handbook Chapter 7, Marcel Dekker, Inc.(1994)

Ken Toyokura、Izumi Hirasawa：“熔体结晶”结晶技术手册第 7 章，Marcel Dekker, Inc.(1994)

K.Toyokura,I.Hirasawa: "Crystallization Technology Handbook Chapter Melt Crystallization" Marcel Dekker,

K.Toyokura，I.Hirasawa：“结晶技术手册章节熔融结晶”Marcel Dekker，

K.Toyokura,I.Hirasawa: "Crystallization Technology Handbook Chapter 7 Crystallization from the Melt" Marcel Dekker,Inc, 79 (1994)

K.Toyokura,I.Hirasawa：“结晶技术手册第 7 章熔体结晶”Marcel Dekker,Inc, 79 (1994)

豊倉賢: "晶析法により析出したベンゼン結晶の純度に対する二次核発生の影響" 化学工学会第59年会要旨集.

Ken Toyokura：“二次成核对结晶法沉淀苯晶体纯度的影响”日本化学工程师学会第 59 届年会论文集。

豊倉賢: "晶析法により析出したベンゼン結晶の純度に対する二次核発生の影響" 化学工学第59年会要旨集. 245- (1994)

Ken Toyokura：“二次成核对结晶法沉淀苯晶体纯度的影响”第59届化学工程年会摘要245-（1994）。