Vapor Pressure Measurements for Metal Chloride Systems by the Knudsen Effusion Method

Abstract

Thermodynamic knowledge of metal chlorides, such as vapor pressure and activity in salt/slag, are of remarkable industrial interest, particularly in fields related to the recovery/recycle/reuse of metal materials. In this study, a new apparatus for measuring the vapor pressure of metal chlorides from molten salt/slag was designed and tested with reference compounds. The results are in a good agreement with the available literature data. Using the developed apparatus, vapor pressure measurements for a KCl-NaCl-CaCl 2 system have been performed. Using the measured data the activities of components were obtained. Simultaneously, the activities of components were calculated using a thermodynamic code, Factsage 5.2 wherein the Modified Quasi-chemical Model was employed to obtain the necessary thermodynamic parameters. The both data agree reasonably well with each other. The results suggested that the KCl-NaCl system exhibits similar behavior with ideal solution; while in the KCl-CaCl 2 and NaCl-CaCl 2 systems there are possible interactions between CaCl 2 and KCl/NaCl. For the ternary system KCl-NaClCaCl 2 , in some concentration range (mole fraction of NaCl 0.25-0.50) NaCl behaves as in an ideal solution, suggesting a larger affinity between KCl and CaCl 2 than that between NaCl and CaCl 2 .

Eu[sup 2+]-Activated Ca[sub 8]Zn(SiO[sub 4])[sub 4]Cl[sub 2]: An Intense Green Emitting Phosphor for Blue Light Emitting Diodes

“…It is understandable that Cl and Zn could be evaporated in the form of CaCl 2 and metallic Zn during firing under the reducing atmosphere. 24 That is why excess CaCl 2 and ZnO are added in the reactant as preparation of chlorosilicates and sorosilicate phosphors. [11][12][13][14][15][16][17][18]25 Kang reported that the increase of the mole ratio of Cl/Ca is beneficial to crystallinity and phase purity, resulting in the enhancement luminescence intensity of Ca 8 Mg͑SiO 4 ͒ 4 Cl 2 :Eu 2+ .…”

Thermochemical and Experimental Kinetic Analysis of Potassium Extraction from Ultrapotassic Syenite Using Molten Chloride Salts

“…33 Therefore, the unit activity coefficient has been chosen for the model input. A similar assumption has been applied for the use of CaCl 2 (2KAlSi 3 O 8 + CaCl 2 → CaAl 2 Si 2 O 8 + 4SiO 2 + 2KCl) since there is no experimental activity coefficient available for the whole mix system except for the CaCl 2 −KCl system 34 solely and Anorthite-K-feldspar system solely. 35 This assumption for both systems discussed is then assessed by validating the model against the current experimental investigation.…”

Molten Chloride Thermophysical Properties, Chemical Optimization, and Purification

“…The FactSage calculation also suggests much lower vapor pressure (~30 times lower) compared to the experimental values. However, experimental work [84,85] suggests that the vapor pressures of molten NaCl and KCl at ~100°C above melting point 54 order of magnitude compared to ~0.15 kPa for the baseline salt at ~100°C above melting point. Therefore, the calculation above serves the purpose of showing that the experimentally measured vapor pressure reflects known physics and can be reliable.…”