Abstract
Calcium hydro ychloride is known as the double salts which have been a chemical composition of x Ca(OH) 2·y CaCl2·zH2O. At first, we investigated on the equilibrium of the system Ca(OH)2-CaCl2-H2O, because there are various types of double salts reported of which the conditions for preparation are not known exactly. And then, the equilibrium of the system Ca(OH) 2-CaCl2-KCl-NaCl-H2O were similarly studied, in order to know the condition to get these double salts from sea water, brine or bittern of which Mg2+had already been replaced with Ca2+completely by the treatment with slaked Iime.
As the results of measuring these two kinds of equilibrium, we confirmed that two kinds of double salt existed in these systems and their chemical compositions were shown with 3, 1, 13 and 1, 1, 1 as regard to x, y, z respectively in the above mentioned formula, and then, the conditions for their preparation computed.
We discussed the removal of calcium chloride from de-magnesiumed sea water, brine or bittern by separating such double salts, and concluded that it is impossible to get the double salts from such a dilute solutions of calcium chloride as de-magnesiumed sea water or brine, and only possible when mother liquor or bittern contains 8% or more calcium chloride.
