Phase equilibria of AlCl₃ + FeCl₃ + H₂O, AlCl₃ + CaCl₂ + H₂O, and FeCl₃ + CaCl₂ + H₂O at 298.15 K

Abstract

In the recovery of aluminum from coal fly ash, the phase equilibria of solid−liquid systems are important for purifying the aluminum salts. This research investigated phase equilibria of the ternary systems AlCl 3 + CaCl 2 + H 2 O, AlCl 3 + FeCl 3 + H 2 O, and FeCl 3 + CaCl 2 + H 2 O at 298.15 K using isothermal dissolution method. The corresponding phase diagrams and density diagrams were plotted. Both AlCl 3 + CaCl 2 + H 2 O and AlCl 3 + FeCl 3 + H 2 O systems had one invariant point, two univariate curves, two crystallization regions, and no double salts. The FeCl 3 + CaCl 2 + H 2 O system had two invariant points, three crystallization regions and a double salt (CaCl 2 •2FeCl 3 •8H 2 O) that formed at 298.15 K. There is no solid solution in all the three systems.

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

“…It is then possible to recover selectively scandium from the chloride solutions by resins or extraction methods [60][61][62]. 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].…”

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].…”

Separating NaCl and AlCl3·6H2O Crystals from Acidic Solution Assisted by the Non-Equilibrium Phase Diagram of AlCl3-NaCl-H2O(-HCl) Salt-Water System at 353.15 K

“…It is assumed that the high ion strength in the leaching solution greatly decreased the solubility of FeCl 3 and CaCl 2 , resulting in their precipitation in advance. For instance, the data for the phase equilibrium of the AlCl 3 -CaCl 2 -H 2 O system [7] has provides an example; i.e., the solubility of CaCl 2 sharply fell from 59.52% (13.246 mol/kg) to 0 when the concentration of AlCl 3 rose from 0 to 32.52% (3.610 mol/kg) at 353.15 K. The AlCl 3 -FeCl 3 -H 2 O system [8] showed a similar phenomenon. This means that the solubility of FeCl 3 and CaCl 2 can be significantly reduced in the concentrated salt solution.…”

“…All of these salts are soluble, and their solubility is similar to that of NaCl and AlCl 3 . The phase diagrams [7,8] of the AlCl 3 -FeCl 3 -H 2 O, AlCl 3 -CaCl 2 -H 2 O and FeCl 3 -CaCl 2 -H 2 O systems at 298.15 K were drawn, and then the evaporation process was optimized to achieve the separation of different components. Researchers studied the crystallization separation of crystalline AlCl 3 from fly ash with rich calcium impurities and mainly examined the phase diagrams of binary AlCl 3 -H 2 O systems and ternary AlCl 3 -CaCl 2 -H 2 O systems within a temperature range of 278.15-363.15 K [7], which are very similar to the separation of NaCl from AlCl 3 , meaning that there is the possibility of separating the two salts if there is a phase diagram.…”