The Formation of Hard-to-Dissolve Matter in Dry Salt
Change of Chemical Composition in Mother Liquor on Surface of Cornmon Salt on Drying (Part 2)
1993 Volume 47 Issue 2 Pages 74-80
Details
1993 Volume 47 Issue 2 Pages 74-80
We investigated the process of production of hard-to-dissolve matter, which was caused by the decomposition of magnesium chloride hydrate on drying and was formed in dry salt, and the preventive measure of hard-to-dissolve matter.
As the results, magnesium chloride hydroxide(Mg2(OH)3Cl·4H2O, Mg3(OH)5Cl·4H2O)was formed by storing under the moisture absorption environment after heating MgCl2·6H2O at high temperature which forms MgOHCl. Calcium carbonate was also formed when the dry salt was stored for a long time. From these results, it was considered that magnesium chloride hydroxlde was resolved by proton from CO2 absorbed in moisture, and calcium carbonate was formed from Ca dissolved in moisture and CO32-increased by the decomposition. The alkalinity(pH 4.8)of dry salt which did not form magnesium chloride hydroxide and calcium carbonate was under 1mg-eq./kg.
Therefore, it was considered that the production of hard-to-dissolve matter in dry salt was to be prevented by the control of alkalinity in the salt after drying.
