Papers by Keyword: Disproportionation

Abstract: The disproportionation of AlCl was investigated by thermodynamics analysis. The results demonstrated that Gibbs free energy change of the disproportionation of AlCl decreases with decreasing temperature and increasing the AlCl pressure. The onset temperature of the disproportionation is 1521K in the standard atmosphere, and those are 878K and 1096K, respectively, at the AlCl partial pressure of 5Pa and 200Pa as the AlCl₃ partial pressure is 200Pa. The AlCl equilibrium partial pressure is about 10^-4Pa at 500K, demonstrating that the disproportionation of AlCl is complete below this temperature. The temperature in the condenser used in the experiments was below 1200K and the top near to the water-cooled cover of the furnace should be below 500K, therefore the disproportionation of AlCl occurred and was completed in the condenser.

Abstract: The extraction of aluminum by the AlCl disproportionation process in vacuum was researched using the furnace designed by ourselves. The features of aluminum products were characterized by X-ray diffraction, scanning electronic microscope and energy-dispersive X-ray spectroscopy. The results indicated that the purity of aluminum products increased with decreasing condensation temperature; aluminum products could be oxidized as their size was too small; the residues of the extraction of aluminum from alumina could be further treated with this process to generate metallic aluminum with a little carbon; aluminum products with high Al₄C₃, C and Al₂O₃ impurities could be purified by this process. The conclusions could provide bases for the industrial application of the process.

Abstract: The ionic valence of Ti changed with electrorefining process of Ti in a bath equi-molar mixture of NaCl-KCl containing TiCl_n (n=2 or 3); The average valence was about 2.3 initially, and became about 2.1 after electrolysis. The cathodic current efficiency was getting better with electrolysis. It should be necessary to maintain the average ionic valence lower for efficient electrolysis in the molten salt. The dominant Ti ion and its electrode reaction changed with the addition of NaF-KF in the molten salt; The average valence shifted from about 2 to about 3, and the total amount of Ti in the bath decreased. The result indicates the disproportionation reaction: 3Ti²⁺ = Ti + 2Ti³⁺ is induced by the fluoride addition. The quantity of electricity for Ti deposition changed consequently, and the purity of the Ti deposit was also affected.