Abstract
As the ratio of sodium chloride content to total salts increases in the advanced technology that lowers the permeability of bivalent ions through ion-exchange membranes, it has resulted in increase of the potassium content and decrease of the magnesium content in the produced common grade salt.
For that reason, it is presumed to be difficult to meet the quality conditions of the salt, which are below 0.25 percent as the standard content of potassium and above 0.04 as the ratio of magnesium to moisture (Mg/H2O ratio) for prevention of blocking. Therefore, it is significant to examine the methods of operation of crystallization in order to maintain the quality of products. In this study, the quality of the common grade salt affected by increasing the ratio of sodium chloride to total salts was discussed in relation to the computer simulation, and the methods of operation to satisfy the quality were discussed.
The results were as follows.
1) Cooling the sprinkled bittern over crystals from the temperature in the pan for concentrating mother liquid to 30 degrees decreased the content of potassium in products in the range of 15.7 to 46.9 percent.
2) Increasing the replacement rate from 50 to 100 percent increased the Mg/H2O ratio in products in the range of 15.6 to 41.2 percent.
3) Increasing the concentration ratio from 100 to 120 percent increased the Mg/H2O ratio in products in the range of 13.3 to 21.8 percent.
4) The examination of the cooling temperature of the sprinkled bittern satisfied the quality condition of the content of potassium.
5) It is necessary to build the pan for concentration of the bittern and to examine the replacement rate and the concentration ratio of the bittern in order to satisfy the quality condition of the Mg/H2O ratio.
