Phase Equilibrium Study of the AlCl₃–CaCl₂–H₂O System for the Production of Aluminum Chloride Hexahydrate from Ca-Rich Flue Ash

Abstract

The study of the solid−liquid phase equilibrium for the AlCl 3 −CaCl 2 −H 2 O system is of significance to separate aluminum chloride hexahydrate from the leachate obtained by the reaction of Ca-rich fly ash and a waste hydrochloride from chemical plant. The phase equilibrium data for the binary AlCl 3 −H 2 O system and the ternary AlCl 3 −CaCl 2 −H 2 O system over the temperature range from 278.15 K to 363.15 K were measured. A rigorous and thermodynamically consistent model representing the AlCl 3 −CaCl 2 −H 2 O system developed on the basis of the Pitzer's activity coefficient model embedded in the Aspen Plus. On the basis of this, the phase behavior of the ternary AlCl 3 −CaCl 2 −H 2 O system at different temperatures was visualized with lucidity on an equilateral triangle. The phase-equilibrium diagram generated by modeling was illustrated to identify the course of crystallization to recover AlCl 3 •6H 2 O from the solutions containing calcium chloride. All of these will provide a thermodynamic basis for the separation of aluminum chloride from calcium chloride solutions.

Influence of Na2CO3 and K2CO3 Addition on Iron Grain Growth during Carbothermic Reduction of Red Mud

“…The separation of aluminum and calcium chlorides was previously studied in coal fly ash utilization [63]. In the present case, the high calcium content in the tailings made it possible to use the salting out method and precipitate AlCl 3 •6H 2 O with further pyrolysis to sandy grade alumina production [64][65][66].…”

The controlling role of sodium and carbonate on the atmospheric corrosion rate of aluminum

“…41 The thermodynamic data used with CHNOSZ is based on the work by Benezeth et al for dawsonite, and Al metal and Al oxi-hydroxide solids from Robie and Hemingway, and Tutolo et al [42][43][44] Thermodynamic data for Al aqueous species are from Tagirov and Schott. 45 Thermodynamic data for AlCl 3 •6H 2 O solid along with binary Pitzer parameters for concentrated AlCl 3 electrolyte were obtained from the work of Wang et al 46 Other Pitzer parameters relevant to this system were obtained from the thermodynamic database developed for salt precipitation in a subsurface nuclear waste repository (see Appendix I in Mariner). 47 Construction of activity phase diagrams in Fig.…”

Reductive Smelting of Neutralized Red Mud for Iron Recovery and Produced Pig Iron for Heat-Resistant Castings

“…%) in the slag, it is impractical to process it by alkaline technology, as part of the alkali will be lost due to a chemical reaction with silica. The most perspective slag treatment is a leaching process by hydrochloric acid to obtain aluminum chloride solutions [20,21]. Then, aluminum chloride hexahydrate (AlCl3•H2O) and scandium (Sc) compounds may selectively be extracted from these solutions [22][23][24][25][26][27].…”