It is difficult to prepare pure AlCl3·6H2O through evaporation crystallization in aluminum recovery from leaching coal fly ash by hydrochloric acid

without phase equilibria diagram for AlCl3

CaCl2 and FeCl3 solution. The phase equilibria of AlCl3+CaCl2+H2O

AlCl3+FeCl3+H2O and CaCl2+ FeCl3+H2O ternary systems at 35℃ were investigated using isothermal dissolution method. After solubility and densities were measured

phase diagram and density diagram were plotted against compositions. The phase diagrams of AlCl3+CaCl2+H2O and AlCl3+FeCl3+H2O had two univariant curves and two crystallization zones without formation of double salt or solid solution. Solubility of AlCl3 decreased with increasing concentration of CaCl2 or FeCl3 due to common ion effect. Double salt CaCl2·2FeCl3·7H2O was formed in CaCl2+FeCl3+H2O ternary system. When temperature was increased from 25℃ to 35℃

phase equilibria diagrams of AlCl3+CaCl2+H2O

AlCl3+FeCl3+H2O and CaCl2+FeCl3+H2O were all changed. Crystallization zone of AlCl3·6H2O in AlCl3+CaCl2+H2O and AlCl3+FeCl3+H2O ternary systems was enlarged and crystallization zone of CaCl2·6H2O was converted into crystallization zone of CaCl2·4H2O. Crystallization zone of CaCl2·2FeCl3·8H2O in CaCl2+FeCl3+H2O ternary system was converted into crystallization zone of CaCl2·2FeCl3·7H2O.