Abstract
In November 1983, the authors collected a series of samples during the process of salt production from sea-water in those salt-making factories equipped with different kinds of membrane. They conducted researches mainly on the concentration of brine in those latest salt-making factories from the standpoint of chemistry. The results obtained from the above researches were as follows:
1. After new types of membrane and electrodialyzer were introduced to the factories, the compositions of brine were almost similar to each other. In general, there was a trend for potassium to increase its concentration and for calcium and magnesium to decrease their concentration.
2. In the case of the brine which has high ratio of sodium chloride to the total salt, it was necessary to raise the temperature of the evaporator and to increase the concentration ratio in order to increase the ratio of crystallization of sodium chloride. The abundant concentration of potassium chloride in the mother liquor tended to cause the deposition of potassium chloride.
3. Therefore, it was one of the best ways to supplement the deficiency of calcium chloride and magnesium chloride into the brine or the mother liquor for the purpose of increasing the crystallization ratio of sodium chloride and controlling the deposition of potassium chloride.
4. Due to the use of the customary combination method and to the fact that the scale component in the brine has decreased, there seems to have been less problem about the deposition and adhession of scale into the evaporator. However, one of the factories which has the backward supplying system of brine seems to have some problems about scale deposition.
