Physicochemical properties of molten

Physicochemical properties of molten systems have an applied significance due to their wide use in both technological process planning and in production equipment design. Analysis of various melt properties versus different parameters of the melt enables to infer the interaction mechanism between the initial components, and in some cases, even to estimate the possible composition of the main complex ions formed in the melt [312]. From this point of view, the analysis of isotherms of physicochemical properties versus melt composition and of the magnitude of their deviation from ideal conditions is of most interest. 

Turkdogan, E. T. (1983) Physicochemical Properties of Molten Slags and Glasses, The Metals Society, London... 

In 1963 Dr. Danbk joined the Institute of Inorganic Chemistry of the Slovak Academy of Sciences in Bratislava, of which he was the director in the period 1991-1995. His main field of interest was the physical chemistry of molten salts systems in particular the study of the relations between the composition, properties, and structure of inorganic melts. He developed a method to measure the electrical conductivity of molten fluorides. He proposed the thermodynamic model of silicate melts and applied it to a number of two- and three-component silicate systems. He also developed the dissociation model of molten salts mixtures and applied it to different types of inorganic systems. More recently his work was in the field of chemical synthesis of double oxides from fused salts and the investigation of the physicochemical properties of molten systems of interest as electrolytes for the electrochemical deposition of metals from natural minerals, molybdenum, the synthesis of transition metal borides, and for aluminium production. 

This book includes selected topics on the measurement and evaluation of physicochemical properties of molten electrolytes. It describes the features, properties, and experimental measurement of different physico-chemical properties of molten salt systems used as electrolytes for the production of different metals, metallic layer deposition, as a medium for reactions in molten salts, e.g. precipitation of double oxide powders used for functional and construction ceramics, special parts for steel and copper production, etc. 

Mizuhata, M., Harada, Y., Cha, G. et al. (2004) Physicochemical properties of molten alkali metal carbonates coexisting with inorganic powder. J. Electrochem. Soc., 151, E179. 

Mizuhata, M. and Deki, S. (2005) Effect of Surface Properties of Porous Solid materials on Physicochemical properties of Molten Carbonate, J. Rare Earths, 23, 1. 

Analysis of the physicochemical properties of fluoride and oxyfluoride melts reveals that the complex ions are characterized by coordination numbers that do not exceed seven. Fluoride melts consist of the complex ions MeF72 and MeFe. Molten chloride-fluoride systems initiate the formation of heteroligand complexes of the form MeFgCl2 . Oxyfluoride and oxyfluoride-chloride melts can contain oxyfluoride complexes MeOF63 at relatively low concentrations. The behavior of the more concentrated melts can be attributed to the formation of oxyfluorometalate polyanions. 

The formation of complex ions is an important problem for the study of the structure and properties of molten salts. Several physicochemical measurements give evidence of the presence of complex ions in melts. The most direct methods are the spectroscopic methods which obtain absorption, vibration and nuclear magnetic resonance spectra. Also, the formation of complex ions can be demonstrated, without establishing the quantitative formula of the complexes, by the variation of various physicochemical properties with the composition. These properties are electrical conductivity, viscosity, molecular refraction, diffusion and thermodynamic properties like molar volume, compressibility, heat of mixing, thermodynamic activity, surface tension. 

Nevertheless, the published data on the physico-chemical properties of the molten systems are often incomplete and in many cases the results given by different authors may more or less differ. The reason is that the experimental measurement of the physicochemical properties of inorganic melts is sometimes inadequate. First, because of the shortage of expensive construction material. Second, due to the relatively high costs connected with the construction of unique measurement devices. 

PHYSICOCHEMICAL PROPERTIES OF THE MOLTEN SYSTEM KF—KCI—KBF4—K2T1F6... 

The selected electrol5rte composition is based on the effects of the various components on the physicochemical properties of the molten electrolyte. However, in some cases, the MgCl2 feedstock contains small amounts of another metal chloride such as KCl. Electrical conductivity, density, vapor pressure, interfacial tension, and metal solubility are important properties. A typical composition can be 45 % NaQ, 35 % CaCl2, 10 % KCl, and 10 % MgCl2. The content of MgCl2 must not be too low to avoid codeposition of sodium, although some sodium will always be deposited at a low activity. 

In addition to the original literature, the reader can find more specialized information in a limited number of review articles. The most comprehensive of these are the volumes Fused Salts, edited by Sundheim (1964), and Molten Salt Chemistry, edited by Blander (1964). The physicochemical literature on fused salts has been reviewed by Blomgren and Van Artsdalen (1960), the electrochemical properties and the structure of melts by Bloom and Bockris (1959), and the detailed conductance, transport, and cryoscopic properties of molten salts by Janz and co-workers (1958). The book Electrochemistry of Fused Salts by Delimarskii and Markov (1961) also includes in the English translation much of the Russian work in this field. Finally, EUis (1960) and Sundheim (1962)... 

Analysis of isotherms of physicochemical properties can also clarify the interactions within molten systems that contain oxides. For example, the interaction between potassium fluorotantalate and tantalum oxide, Ta2Os, can be studied using density isotherms of molten mixtures. Fig. 68 demonstrates the dependence of the density on K2TaF7 concentration for mixtures K2TaF7 -KF - KC1 and K2TaF7 - KF - KC1 - Ta2Os. 

For the case of FTS and CO methanation in molten wax slurry system the parameters Involved in model equations, i.e. the physicochemical properties, the hydro-dynamic and mass transfer parameters, can be estimated with sufficient accuracy. There exist reliable data for the physicochemical properties obtained from independent measurements and summarized by Hammer (14) and Declcwer and coworkers (15). The hydrodynamic and mass transfer parameters can be calculated from empirical correlations given by Deckwer et al. (15), which were partly established from measurements in Icibscale reactors under synthesis conditions and seem to be applicable for larger scale equipment (17). This data and correlations were successfully used to perform a kinetic study on the experimental data reported in the literature on the FTS (16) and to simulate the results obtained in the Rheinpreussen-Koppers demonstration plant predicting fairly well the optimal gas velocity (17,18). 

Nunes VMB, Lourenco MJV, Santos FJV, Lopes MLSM, Nieto de Castro CA (2010) Accurate measurement of physicochemical properties on ionic liquids and molten salts. In Gaune-Escard M, Seddon KR (eds) Molten salts and ionic liquids never the twain Wiley, New York, pp 229-263... 

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