Experimental measurements were made to assess the electrical conductivity as a function of temper... more Experimental measurements were made to assess the electrical conductivity as a function of temperature and NdF3 concentration (0–20 mol %) of molten systems of (LiF–CaF2)eut–NdF3, (LiF–NaF)eut–NdF3, (NaF–CaF2)eut–NdF3 and (LiF–MgF2)eut–NdF3. The experiment used an altering current impedance spectroscopy technique with a platinum–rhodium electrode positioned in a pyrolytic BN tube and graphite a crucible/counter electrode. The conductivity of all systems under study increased with rising temperatures and decreasing NdF3 concentrations. The Arrhenius equation and linear regression have both been used to describe the experimental data. The results of the ionic conductivity for the temperature 850 °C and NdF3 concentrations 0, 10 and 15 mol %, respectively, can be compared as follows: the conductivity of the molten system of (LiF–CaF2)eut–NdF3 was determined to be 6.10, 5.95 and 5.10 S.cm−1, the results for the system (LiF–NaF)eut–NdF3 were 6.16, 5.56 and 4.13 S.cm−1, the results for th...
For the first time, the mechanism of metal aluminum dissolution in NaF-ScF 3 eutectic melts and t... more For the first time, the mechanism of metal aluminum dissolution in NaF-ScF 3 eutectic melts and the chemical interaction between the constituents of this mixture have been thoroughly studied by a combination of differential thermal analysis (DTA), high temperature and solid-state nuclear magnetic resonance (NMR), and X-ray diffraction (XRD) coupled with the molecular dynamic simulations. The formation of an insoluble Al 3 Sc alloy in molten (NaF-ScF 3) eut system was proven, and the chemical mechanism of this aluminothermic Al 3 Sc alloy production was elucidated. Corresponding ex situ examinations bring to light the formation of NaScF 4 and solid solution of Na 3 (Al,Sc)F 6 in cooled bath. The molecular dynamics calculations of the bath allow us to construct the structural model and to predict viscosity, density and electrical conductivity of the reagent melt to help to optimize the conditions of the alloy synthesis.
The influence of sulfur species on the current efficiency and carbon consumption in the aluminum ... more The influence of sulfur species on the current efficiency and carbon consumption in the aluminum electrolysis was investigated. Prebaked and graphite anodes with varying levels of sulfur were used. It was found that increasing the sulfur content in the anodes decreases the current efficiency and increases the carbon consumption of both types of anodes. The current efficiency decreased by 1.3 pct and the carbon consumption rose by 6.1 pct per 1 wt pct S in the prebaked anodes. The addition of sodium sulfate to the electrolyte during electrolysis with graphite anodes led to a decrease in current efficiency from 0.9 to 1.0 pct per 1 wt pct S, and to an increase in carbon consumption from 3.1 to 7.0 pct per 1 wt pct S. Electrolyte analysis showed the presence of sulfates, sulfides and polysulfides. Some link between sulfur content in the anodes and sulfur content in the electrolyte and outgoing gases was found. A comparison of the polarized and non-polarized conditions showed that the electrolysis increases the sulfur depletion from the cell and promotes the formation of soluble sulfides. Reactions of sulfur participation in redox processes have also been proposed.
Experimental measurements were made to assess the electrical conductivity as a function of temper... more Experimental measurements were made to assess the electrical conductivity as a function of temperature and NdF 3 concentration (0-20 mol %) of molten systems of (LiF-CaF 2) eut-NdF 3 , (LiF-NaF) eut-NdF 3 , (NaF-CaF 2) eut-NdF 3 and (LiF-MgF 2) eut-NdF 3. The experiment used an altering current impedance spectroscopy technique with a platinum-rhodium electrode positioned in a pyrolytic BN tube and graphite a crucible/counter electrode. The conductivity of all systems under study increased with rising temperatures and decreasing NdF 3 concentrations. The Arrhenius equation and linear regression have both been used to describe the experimental data. The results of the ionic conductivity for the temperature 850 °C and NdF 3 concentrations 0, 10 and 15 mol %, respectively, can be compared as follows: the conductivity of the molten system of (LiF-CaF 2) eut-NdF 3 was determined to be 6.10, 5.95 and 5.10 S.cm −1 , the results for the system (LiF-NaF) eut-NdF 3 were 6.16, 5.56 and 4.13 S.cm −1 , the results for the system (NaF-CaF 2) eut-NdF 3 were 3.78, 3.56 and 2.32 S.cm −1 , and finally, the results for the system (LiF-MgF 2) eut-NdF 3 were determined to be for the same temperature as 5.35, 4.79 and 4.14 S.cm −1 , respectively.
In an experiment combining various approaches, a precise examination of a portion of the phase di... more In an experiment combining various approaches, a precise examination of a portion of the phase diagram of a CsF− Al 2 O 3 system was carried out up to 40 mol% Al 2 O 3. CsF−Al 2 O 3 solidified mixtures have been investigated using high-field solidstate NMR (133 Cs, 27 Al, and 19 F) spectroscopy and X-ray powder diffraction over a broad range of compositions with synchrotron powder diffraction and Rietveld analysis. A new cesium oxo-fluoroaluminate, Cs 2 Al 2 O 3 F 2 , was discovered, prepared, and structurally analyzed by synchrotron diffraction analysis. In addition to Cs 2 Al 2 O 3 F 2 , we have synthesized the following pure compounds in order to aid in the interpretation of NMR spectra of the solidified samples: CsAlF 4 , Cs 3 AlF 6 , and CsAlO 2 .
Journal of Chemical & Engineering Data, Feb 27, 2008
... or decreases the formation of alumina sludge between the carbon lining and the liquid aluminu... more ... or decreases the formation of alumina sludge between the carbon lining and the liquid aluminumcathode. The IFT also plays a significant role in the refining and the recycling of aluminum ... However, by the usage of an X-ray beam, the shape of sessile drops immersed in another ...
ABSTRACT Density, viscosity and electrical conductivity of the molten system Na 3AlF 6–SiO 2 have... more ABSTRACT Density, viscosity and electrical conductivity of the molten system Na 3AlF 6–SiO 2 have been investigated in the concentration range up to 50 mole % of SiO 2. Density was measured by means of a computerized Archimedean method, viscosity of the melt by computerized torsion pendulum method and the electrical conductivity by means of the tube–cell (pyrolytic boron nitride) with stationary electrodes. It was found that the density, viscosity and conductivity vary linearly with the temperature in all investigated mixtures. On the basis of the density data, the molar volume of the melts and the partial molar volume have been calculated.
Abstract The effect of anode quality as well as operational parameters of aluminum electrolysis o... more Abstract The effect of anode quality as well as operational parameters of aluminum electrolysis on the composition of anode gases, such as carbon monoxide, carbon dioxide and the content of fluorine species, was studied in the laboratory under controlled conditions. Experiments using anodes made of spectral graphite (SG), pyrolytic graphite (PG) and industrial prebaked anode carbon were carried out. The experimental set up allowed us to estimate the current efficiency and to determine the mechanism of anode carbon consumption. Particular interest was paid to the ‘dusting’ of anodes which is an important parameter characterizing the quality of industrial anodes. On a étudié en laboratoire, sous des conditions contrôlées, l’effet de la qualité de l’anode ainsi que les paramètres de fonctionnement de l’électrolyse de l’aluminium sur la composition des gaz de l’anode, i.e. le monoxyde de carbone, le bioxyde de carbone et la teneur en espèces du fluor. Nous avons effectué des expériences en utilisant des anodes faites de graphite spectral (SG), de graphite pyrolytique (PG) et une anode industrielle de carbone pré-cuit. Le dispositif expérimental nous a permis d’estimer le rendement du courant et de déterminer le mécanisme de consommation de carbone à l’anode. On a particulièrement prêté attention au poudrage des anodes, qui est un paramètre important caractérisant la qualité des anodes industrielles.
An entry from the Inorganic Crystal Structure Database, the world's repository for inorganic ... more An entry from the Inorganic Crystal Structure Database, the world's repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Experimental measurements were made to assess the electrical conductivity as a function of temper... more Experimental measurements were made to assess the electrical conductivity as a function of temperature and NdF3 concentration (0–20 mol %) of molten systems of (LiF–CaF2)eut–NdF3, (LiF–NaF)eut–NdF3, (NaF–CaF2)eut–NdF3 and (LiF–MgF2)eut–NdF3. The experiment used an altering current impedance spectroscopy technique with a platinum–rhodium electrode positioned in a pyrolytic BN tube and graphite a crucible/counter electrode. The conductivity of all systems under study increased with rising temperatures and decreasing NdF3 concentrations. The Arrhenius equation and linear regression have both been used to describe the experimental data. The results of the ionic conductivity for the temperature 850 °C and NdF3 concentrations 0, 10 and 15 mol %, respectively, can be compared as follows: the conductivity of the molten system of (LiF–CaF2)eut–NdF3 was determined to be 6.10, 5.95 and 5.10 S.cm−1, the results for the system (LiF–NaF)eut–NdF3 were 6.16, 5.56 and 4.13 S.cm−1, the results for th...
For the first time, the mechanism of metal aluminum dissolution in NaF-ScF 3 eutectic melts and t... more For the first time, the mechanism of metal aluminum dissolution in NaF-ScF 3 eutectic melts and the chemical interaction between the constituents of this mixture have been thoroughly studied by a combination of differential thermal analysis (DTA), high temperature and solid-state nuclear magnetic resonance (NMR), and X-ray diffraction (XRD) coupled with the molecular dynamic simulations. The formation of an insoluble Al 3 Sc alloy in molten (NaF-ScF 3) eut system was proven, and the chemical mechanism of this aluminothermic Al 3 Sc alloy production was elucidated. Corresponding ex situ examinations bring to light the formation of NaScF 4 and solid solution of Na 3 (Al,Sc)F 6 in cooled bath. The molecular dynamics calculations of the bath allow us to construct the structural model and to predict viscosity, density and electrical conductivity of the reagent melt to help to optimize the conditions of the alloy synthesis.
The influence of sulfur species on the current efficiency and carbon consumption in the aluminum ... more The influence of sulfur species on the current efficiency and carbon consumption in the aluminum electrolysis was investigated. Prebaked and graphite anodes with varying levels of sulfur were used. It was found that increasing the sulfur content in the anodes decreases the current efficiency and increases the carbon consumption of both types of anodes. The current efficiency decreased by 1.3 pct and the carbon consumption rose by 6.1 pct per 1 wt pct S in the prebaked anodes. The addition of sodium sulfate to the electrolyte during electrolysis with graphite anodes led to a decrease in current efficiency from 0.9 to 1.0 pct per 1 wt pct S, and to an increase in carbon consumption from 3.1 to 7.0 pct per 1 wt pct S. Electrolyte analysis showed the presence of sulfates, sulfides and polysulfides. Some link between sulfur content in the anodes and sulfur content in the electrolyte and outgoing gases was found. A comparison of the polarized and non-polarized conditions showed that the electrolysis increases the sulfur depletion from the cell and promotes the formation of soluble sulfides. Reactions of sulfur participation in redox processes have also been proposed.
Experimental measurements were made to assess the electrical conductivity as a function of temper... more Experimental measurements were made to assess the electrical conductivity as a function of temperature and NdF 3 concentration (0-20 mol %) of molten systems of (LiF-CaF 2) eut-NdF 3 , (LiF-NaF) eut-NdF 3 , (NaF-CaF 2) eut-NdF 3 and (LiF-MgF 2) eut-NdF 3. The experiment used an altering current impedance spectroscopy technique with a platinum-rhodium electrode positioned in a pyrolytic BN tube and graphite a crucible/counter electrode. The conductivity of all systems under study increased with rising temperatures and decreasing NdF 3 concentrations. The Arrhenius equation and linear regression have both been used to describe the experimental data. The results of the ionic conductivity for the temperature 850 °C and NdF 3 concentrations 0, 10 and 15 mol %, respectively, can be compared as follows: the conductivity of the molten system of (LiF-CaF 2) eut-NdF 3 was determined to be 6.10, 5.95 and 5.10 S.cm −1 , the results for the system (LiF-NaF) eut-NdF 3 were 6.16, 5.56 and 4.13 S.cm −1 , the results for the system (NaF-CaF 2) eut-NdF 3 were 3.78, 3.56 and 2.32 S.cm −1 , and finally, the results for the system (LiF-MgF 2) eut-NdF 3 were determined to be for the same temperature as 5.35, 4.79 and 4.14 S.cm −1 , respectively.
In an experiment combining various approaches, a precise examination of a portion of the phase di... more In an experiment combining various approaches, a precise examination of a portion of the phase diagram of a CsF− Al 2 O 3 system was carried out up to 40 mol% Al 2 O 3. CsF−Al 2 O 3 solidified mixtures have been investigated using high-field solidstate NMR (133 Cs, 27 Al, and 19 F) spectroscopy and X-ray powder diffraction over a broad range of compositions with synchrotron powder diffraction and Rietveld analysis. A new cesium oxo-fluoroaluminate, Cs 2 Al 2 O 3 F 2 , was discovered, prepared, and structurally analyzed by synchrotron diffraction analysis. In addition to Cs 2 Al 2 O 3 F 2 , we have synthesized the following pure compounds in order to aid in the interpretation of NMR spectra of the solidified samples: CsAlF 4 , Cs 3 AlF 6 , and CsAlO 2 .
Journal of Chemical & Engineering Data, Feb 27, 2008
... or decreases the formation of alumina sludge between the carbon lining and the liquid aluminu... more ... or decreases the formation of alumina sludge between the carbon lining and the liquid aluminumcathode. The IFT also plays a significant role in the refining and the recycling of aluminum ... However, by the usage of an X-ray beam, the shape of sessile drops immersed in another ...
ABSTRACT Density, viscosity and electrical conductivity of the molten system Na 3AlF 6–SiO 2 have... more ABSTRACT Density, viscosity and electrical conductivity of the molten system Na 3AlF 6–SiO 2 have been investigated in the concentration range up to 50 mole % of SiO 2. Density was measured by means of a computerized Archimedean method, viscosity of the melt by computerized torsion pendulum method and the electrical conductivity by means of the tube–cell (pyrolytic boron nitride) with stationary electrodes. It was found that the density, viscosity and conductivity vary linearly with the temperature in all investigated mixtures. On the basis of the density data, the molar volume of the melts and the partial molar volume have been calculated.
Abstract The effect of anode quality as well as operational parameters of aluminum electrolysis o... more Abstract The effect of anode quality as well as operational parameters of aluminum electrolysis on the composition of anode gases, such as carbon monoxide, carbon dioxide and the content of fluorine species, was studied in the laboratory under controlled conditions. Experiments using anodes made of spectral graphite (SG), pyrolytic graphite (PG) and industrial prebaked anode carbon were carried out. The experimental set up allowed us to estimate the current efficiency and to determine the mechanism of anode carbon consumption. Particular interest was paid to the ‘dusting’ of anodes which is an important parameter characterizing the quality of industrial anodes. On a étudié en laboratoire, sous des conditions contrôlées, l’effet de la qualité de l’anode ainsi que les paramètres de fonctionnement de l’électrolyse de l’aluminium sur la composition des gaz de l’anode, i.e. le monoxyde de carbone, le bioxyde de carbone et la teneur en espèces du fluor. Nous avons effectué des expériences en utilisant des anodes faites de graphite spectral (SG), de graphite pyrolytique (PG) et une anode industrielle de carbone pré-cuit. Le dispositif expérimental nous a permis d’estimer le rendement du courant et de déterminer le mécanisme de consommation de carbone à l’anode. On a particulièrement prêté attention au poudrage des anodes, qui est un paramètre important caractérisant la qualité des anodes industrielles.
An entry from the Inorganic Crystal Structure Database, the world's repository for inorganic ... more An entry from the Inorganic Crystal Structure Database, the world's repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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