Abstract
Because concentrated bittern from an ion exchange membrane process contains calcium chloride in addition to magnesium chloride as the principal ingredient, the procedure usually applied to concentrated bittern from the conventional process, namely evaporation concentration at atmospheric pressure in liquid state to form flakes or fine grains, cannot be applied to concentrated bittern from the membrane process.
Thus, for the purpose of finding a way out of such difficulties, viscosities (CP) of MgCl2-H2O, CaCl2-H2O, MgCl2-CaCl2-H2O as well as of solutions having compositions corresponding to the above two concentrated bitterns were measured in the course of their evaporation concentration, in this study, As the results, it was found that the presence of KCl in a certain concentration range was effective for the purpose. For instance, by adding 3-5% KCl to an aqueous solution containing 20% MgCl2 and 7-9% CaCl2, comparable to concentrated bittern of the membrane process in composition, it was found that at the concentration temperature of 158°C, CP was about 20 after evaporation concentration and the finished products remained in liquid state, similarly to the case of concentrated bittern from the conventional process.
