Prccipitation phenomena of calcite and research for apparatus and operational conditions

方解石的沉淀现象及装置和操作条件的研究

基本信息

批准号：
07455316
负责人：
TOYOKURA Ken
金额：
$ 4.29万
依托单位：
Waseda University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Calcium carbonate precipitated by the reaction between calcium chloride solution and sodium carbonate solution was studied. In this reaction calcium carbonate intermediate was came out in the initial reaction step, and then transformed to mixture of calcite and vaterite in the reacting solution, and transformation of intermediate was focused in this study. Sodium chloride crystal was added to reacting slurry in which intermediate was coexisted, calcite was precipitated dominantly. Crystal size and precipitated number of calcite was affected by the crystal size of added sodium chloride crystal and crystal growth rate of calcite was obtained in the reacting slurry which intermediate was coexisted. On the other hand, calcite precipitated dominantly by reaction between calcium chloride solution and sodium bicarbonate solution. In this reaction, precipitated number of calcite was correlated with the amount of sodium bicarbonate and it was considered that transformation of intermediate to calcite was promoted by decomposition of bicarbonate ions.In the case of double jet reactive crystallization method wihch is applied for precipitation of silver halide industry, precipitated calcium carbonate was mixture of calcite and vaterite and it was not found the operational conditions which calcite precipitated dominantly. Therefore nucleating agent were considered to be necessary in this system.Crystallization phenomena of calcite in the stationary solution was studied. It was found that mixture of calcite and vaterite was precipitated within the range of average supersaturation which was calculate by the values of pH from 100 to 250. But the calcite was precipitated in the range of average supersaturation under 50 or over 280.

研究了通过氯化钙溶液与碳酸钠溶液之间的反应沉淀的碳酸钙。在此反应中，碳酸盐钙中间体在初始反应步骤中出现，然后转化为反应溶液中方解石和vathite的混合物，并将中间体的转化集中在这项研究中。将氯化钠晶体添加到中间体共存的反应浆液中，对方解石进行了主要沉淀。晶体大小和沉淀的方解石数受到添加的氯化钠晶体的晶体大小的影响，并在中间体共存的反应浆中获得方解石的晶体生长速率。另一方面，方解石通过氯化钙溶液和碳酸氢钠溶液之间的反应显着沉淀。 In this reaction, precipitated number of calcite was correlated with the amount of sodium bicarbonate and it was considered that transformation of intermediate to calcite was promoted by decomposition of bicarbonate ions.In the case of double jet reactive crystallization method wihch is applied for precipitation of silver halide industry, precipitated calcium carbonate was mixture of calcite and vaterite and it was not found the operational conditions which calcite precipitated主要。因此，在该系统中认为成核剂被认为是必要的。研究了固定溶液中方解石的结晶现象。发现在平均过饱和度范围内沉淀了方解石和vatater石的混合物，这是通过pH值从100到250的值计算得出的。但是，在平均过饱和度50或超过280的平均过饱和范围内，方解石是沉淀的。