Showing papers on "Molten salt published in 1980"

The Interpretation of Ionic Conductivity in Liquids

Abstract: 1. Introduction and Definitions.- 1.1. Introduction.- 1.2. Electrical Conductivity.- 1.3. Diffusion and Viscosity.- 1.3.1. The Diffusion Coefficient.- 1.3.2. Viscosity.- 1.4. The Stokes-Einstein and Nernst-Einstein Relations.- 1.4.1. The Stokes-Einstein Relation.- 1.4.2. The Nernst-Einstein Relation.- 1.4.3. The Walden Product.- 2. Ionic Conductivity in Dilute Electrolyte Solutions.- 2.1. Concentration Dependence of Conductivity of Dilute Electrolyte Solutions-Introduction.- 2.1.1. Derivation of the Conductance Equations.- 2.1.2. The Relaxation Effect.- 2.1.3. The Electrophoretic Effect.- 2.1.4. Conductivity Equations for Nonassociated Electrolytes.- 2.1.5. Conductivity Equations for Associated Electrolytes.- 2.1.6. Test of the Conductivity Equation.- 2.2. The Concentration Dependence of Conductivity at High Pressure and Moderate Temperatures.- 2.3. The Concentration Dependence of Conductivity at High Pressure and Temperature.- 2.4. The Effect of Pressure on Electrical Conductivity at Ambient Temperatures.- 2.4.1. Hydrogen-Bonded Solvents.- 2.4.2. Neutral Solvents.- 2.5. The Effect of Pressure on the Conductivity of Electrolyte Solutions at High Temperatures and Pressures.- 2.6. Excess H+ and OH- Mobility in Aqueous Solutions.- 2.7. The Limiting Ionic Conductivity of Ions in Solution.- 2.7.1. The Molecular Hydrodynamic Approach.- 2.7.2. The Transition State Theory.- 3. Ionic Conductivity in Low-Temperature Molten Salts and Concentrated Solutions.- 3.1. The Transition from Dilute Solutions to Molten Salts.- 3.2. Composition Dependence of Conductance in Concentrated Solutions and Low-Temperature Molten Salts.- 3.2.1. The Dilute Solution Approach.- 3.2.2. The Molten Salt Approach.- 3.3. Temperature and Pressure Dependence of Conductance in Concentrated Solutions and Low-Temperature Molten Salts.- 3.4. Electrical Relaxation in Glass-Forming Molten Salts.- 4. Electrical Conductivity in Ionic Liquids at High Temperatures.- 4.1. The Temperature and Pressure Dependence of Electrical Conductivity in Ionic Liquids.- 4.2. Theories for Electrical Conductivity in Ionic Melts.- 4.2.1. Transition State Theory.- 4.2.2. The Hole Model of Liquids.- 4.2.3. The Theory of Significant Liquid Structures.- 4.2.4. The Kirkwood-Rice-Allnatt Kinetic Theory of Electrical Conductance.- 4.2.5. The "Free Ion" Theory of Conductance of Barton and Speedy.- 4.2.6. Other Theories.- 5. Ionic Conductivity in Molecular Liquids and Partially Ionized Molten Salts.- 5.1. Introduction.- 5.2. The Temperature and Pressure Dependence of Conductivity.- 5.3. Conclusions.- 6. Electrical Conductivity in Liquids of Geological and Industrial Interest.- 6.1. Geological Liquids.- 6.1.1. Seawater.- 6.1.2. Geothermal Waters.- 6.1.3. Silicate Melts and Magmas.- 6.2. Industrial Electrolytes.- 6.2.1. Aqueous Industrial Electrolytes.- 6.2.2. Nonaqueous Electrolyte Solutions.- 6.2.3. Molten Salt Electrolytes.- References.

Molten salt lithium cells

Abstract: Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400°-500° C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell (10) which may be operated at temperatures between about 100°-170° C. Cell (10) comprises an electrolyte (16), which preferably includes lithium nitrate, and a lithium or lithium alloy electrode (12).

The Electrochemical Behavior of Aluminum in the Low Temperature Molten Salt System n Butyl Pyridinium Chloride: Aluminum Chloride and Mixtures of This Molten Salt with Benzene

Abstract: The aluminum deposition and stripping processes at tungsten, platinum, and glassy carbon electrodes in the low temperature molten salt system, n butyl pyridinium chloride: aluminum chloride, and the 50 volume percent (v/o) mixture of this molten salt with benzene have been investigated, using a variety of electrochemical techniques. At all three electrodes, and in both solvent systems, the deposition reaction in slightly acidic melts, the reduction of ions, was found to involve a nucleation process while at the tungsten and platinum electrodes underpotential deposition was also observed. Reduction of the n butyl pyridinium cation was found to occur at −1.1V vs. Al(2:1 melt) which is positive of the reduction potential of ions and therefore aluminum deposition in basic melts was not observable. Studies of the stripping of aluminum from inert substrates showed that aluminum is very slowly corroded in acidic melts, and melt‐benzene mixtures, by traces of oxidizing impurities while in basic systems aluminum reduces the n butyl pyridinium cation. Potentiometric titration of the 50 v/o melt‐benzene mixture showed that the acid‐base properties of this system are defined, as in the pure melt, by the equilibrium with an equilibrium constant of at 30°C.

Molten Salts: Volume 5, Part 2. Additional Single and Multi-Component Salt Systems. Electrical Conductance, Density, Viscosity and Surface Tension Data

Abstract: Data on the electrical conductance, density, and surface tension of more than ninety additional multi‐component salt systems have been systematically collected and evaluated. Results are given for mixtures over a range of compositions and temperatures. Values of the above properties for some sixty single salt systems are also reported.

Inert electrode formulations

Abstract: Disclosed is an inert electrode composition suitable for use in the electrolytic production of metal from a metal compound dissolved in a molten salt. The electrode comprises a ceramic oxide composition and at least one metal powder dispersed through the ceramic oxide composition for purposes of increasing its conductivity, the metal powder selected from the group consisting of Ni, Cu, Co, Pt, Rh, In and Ir.

Electrolytic production of aluminum using a composite cathode

Abstract: A metal such as aluminum is produced by electrolysis of a compound of the metal in a solvent or bath such as molten salt. Electrolysis is carried out by passing a current from an anode to a cathode between which the solvent bath is situated. The cathode is composed of a composite comprising graphite and a refractory hard metal such as titanium diboride. The properties and performance of the composite cathode are improved through careful manufacturing controls and selectivity with respect to electrode configuration and cell operating conditions.

Composition for inert electrodes

Abstract: Disclosed is a composition suitable for fabricating into an inert electrode for use in the electrolytic production of metal from a metal compound dissolved in a molten salt. The electrode comprises at least two metal oxides combined to provide a combination metal oxide consisting essentially of a composition defined by the formula M(M' y M 1-y ) z O K where y is a number less than one and greater than 0 and M is a metal having a valence selected from the group consisting of 2, 3, 4 and 5 and M' is a metal having a valence selected from the group consisting of 2, 3, 4 and 5, z is a number selected from the group consisting of 2, 3 and 4 and K is a number in the range of 2 to 4.4, the electrode being highly conductive and being substantially inert with respect to the molten salt.

The structure and surface tension of the liquid-vapour interface of a model of a molten salt

Abstract: We present results of calculations of the equilibrium density profile and surface tension for the liquid-vapour interface of the restricted primitive model of a molten alkali halide. In this model the anion and cation are represented by hard spheres of equal diameter R and opposite charges; there is no electrical double layer at the interface. Our calculations are based on a square gradient approximation to the free energy of an inhomogeneous charged fluid. We find that the shape of the total density profile is different from that calculated for a Lennard-Jones fluid and that the interfacial thickness is somewhat sharper at low temperatures; the ‘10–90’ thickness is ≈ R near the melting temperature. The surface tension decreases linearly with temperature until near the critical point, in a manner similar to that found for the Lennard-Jones fluid. Our results are in qualitative agreement with the results of a recent computer simulation for a model of KCl. We have also compared our result for the surface te...

Disposal of pcb

Abstract: A process for the decomposition of polychlorinated biphenyls (PCB's) with negligible environmental pollution. The process comprises feeding the PCB and a source of oxygen to a molten salt comprising an alkali metal carbonate and preferably also an alkali metal sulfate to decompose the PCB by pyrolysis and oxidation. Some of the resulting decomposition products react with and are retained in the molten salt; the remaining gaseous products pass through the melt and are safely exhaustable to the atmosphere or, alternatively, the PCB is introduced into a first zone for partial pyrolysis and oxidation and then into a second reaction zone for further oxidation of any remaining combustible gases.

Method of producing aluminum using graphite cathode coated with refractory hard metal

Abstract: A metal such as aluminum is produced by electrolysis of a compound of the metal in a solvent such as a molten salt. Electrolysis is carried out by passing a current from an anode to a cathode between which the solvent bath is situated. The cathode or cathode member is composed of a graphite substrate coated with a refractory hard metal such as titanium diboride. The coating adhesion of the TiB2 is improved through control of the manufacture and structure of the graphite substrate to favor a higher coefficient of thermal expansion and to have the density of the graphite fall within a range of 1.6 to 1.85 grams per cubic centimeter. The steps in producing the graphite may include working it so as to provide a grain direction. One embodiment includes aligning the refractory hard metal coated graphite in the electrolytic cell with the graphite grain direction parallel to the direction of current flow from anode to cathode. The refractory hard metal coating can be imparted by chemical vapor deposition and should exhibit a dense columnar structure which reduces penetration of the coating by molten aluminum.

Optical absorption of dilute solutions of metals in molten salts

Abstract: The F-centre model for the bound state and the first optical transition of an electron in a metal-molten-salt solution is examined in the high-dilution limit appropriate for comparison with optical absorption data. It is first argued that the model is consistent with recent neutron diffraction and computer simulation data on the structure of pure molten salts, and not incompatible with an Anderson localization model for the electronic conductivity of the solution at higher concentration of metal. A detailed evaluation of the model is presented for the case of a molten salt of equi-sized ions simulating molten KC1. The treatment of the electronic states is patterned after semicontinuum approximations previously applied to the F-centre in ionic crystals, but the equilibrium radius of the electronic cavity and its fluctuations are determined self-consistently from the free energy of the solution. The detailed analysis of this case and the agreement of the results with experiment allow the constructi...

Ternary compound electrode for lithium cells

Abstract: Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and of light weight. One type of lithium-based cell utilizes a molten salt electrolyte and normally is operated in the temperature range of about 350°-500° C. Such high temperature operation accelerates corrosion problems. The present invention provides an electrochemical cell in which lithium is the electroactive species. The cell has a positive electrode which includes a ternary compound generally represented as Li-M-O, wherein M is a transition metal. Corrosion of the inventive cell is considerably reduced.

Molten salt synthesis of alkaline earth titanates, zirconates and their solid solutions

Abstract: A particulate mixture of an alkali metal hydroxide solvent, a reactant selected from the group consisting of titanium oxide, zirconium oxide and mixtures thereof, and an alkaline earth reactant selected from the group consisting of barium oxide, strontium oxide, and mixtures thereof, is heated to melt the alkali metal hydroxide solvent in which the reactants dissolve and react precipitating a titanate, zirconate or solid solutions thereof.

Ceramic oxide electrodes for molten salt electrolysis

Abstract: A substantially non-consumable anode used in the production of aluminium from a cryolite-based fused bath containing alumina consists of a sintered self-sustaining ceramic oxide body of spinel structure which is made conductive by selective partial substitution, the introduction of non-stoichiometry or by doping so as to maintain the impurities in the produced aluminium at low levels. Preferred materials are partially-substituted nickel ferrite spinels.

Composition Gradients in Molten Salt Binary Mixtures during Electrolysis at High Current Density

Abstract: Separation of components has been measured in binary molten salt mixtures, AgNO3-KNO3, subjected to electrolysis between silver electrodes. The analysis of thin slices of frozen mixture contained in silica frits gives qualitatively the composition changes between anode and cathode and shows the expected enrichment of potassium ions at the cathode. Changes in concentration at the electrodes are measured electrochemicall y in free electrolytes and in electrolytes contained in frits. The time dependence of concentration at the electrodes is obtained both during electrolysis and during relaxation following electrolyses of different durations. The experimental results confirm the predictions from a mass transport model proposed previously for systems analogous to mixed molten salt batteries operated at high current densities.

Molten salt synthesis of alkaline zirconate powder

Abstract: A particulate mixture of an alkali chloride solvent salt, zirconium oxide and an alkaline earth reactant selected from the group consisting of barium oxide, strontium oxide, and mixtures thereof, is heated to melt the chloride salt solvent in which the zirconium oxide and alkaline earth reactant dissolve and react precipitating a zirconate selected from the group consisting of barium zirconate, strontium zirconate and mixtures thereof.

Facility for conducting electrical power to electrodes

Abstract: The new conductor facility for electrodes, in particular for electrodes immersed in corrosive molten salts, features the following components: (a) A graphite pipe or tube which is open at both ends, fits tightly into a recess in the electrode and passes through the furnace or cell wall or roof. (b) A metallic electrical conductor, which is positioned inside the graphite pipe and can be pushed forward inside it, is made of a metal with a melting point lower than the temperature of the molten salt charge and makes contact with the electrode in the liquid state at the operating temperature of the furnace or cell. (c) A protective pipe, which surrounds the graphite pipe and is made of a dense, electrically insulating ceramic material, has one end tightly embedded in the electrode and the other end passing through the wall or roof, and is stable under the operating conditions of the furnace or cell. The said conductor facility is suitable for smelting furnaces, electrolytic cells for the production of metals, in particular from their chlorides dissolved in chloride bearing melts, and for equipment of a similar kind. It is self-regenerative and permits operation under conditions of constant power supply.

System and process for storing energy

Abstract: SYSTEM AND PROCESS FOR STORING ENERGY There is disclosed a process for storing energy by use of the heat of fusion of hydrated salts which are within a bulk container having heat exchange means. The process prevents stratification and super-cooling from occurring during the heat releasing cycles by internally circulating the molten salt within the container and also by preventing the temperature of the salt from rising above that at which complete melting of the salt crystals within the container occurs.

Nuclear performance of molten salt fusion-fission symbiotic systems for catalyzed deuterium-deuterium and deuterium-tritium reactors.

Abstract: The nuclear performance of a fusion-fission hybrid reactor having a molten salt composed of Na-Th-F-Be as the blanket fertile material and operating with a catalyzed deuterium-deuterium (DD) plasma...

Some Alternate Fabrication Processes for Molten Carbonate Fuel Cell Electrolyte Structures

Abstract: A process is presented for the preparation of reinforced molten carbonate fuel cell electrolyte structures which does not involve a hot‐pressing operation. This process is based on the use of an electrolyte‐free matrix material of predetermined, tailored characteristics. The matrix is fabricated into a "blank" using conventional ceramic techniques. The "blank" is subsequently infiltrated under controlled conditions with molten electrolyte.

Process of converting ethylbenzene to styrene by catalytic dehydrogenation

Abstract: The invention relates to a process of converting ethylbenzene to styrene by catalytic dehydrogenation at temperatures of about 600° C. in the presence of water vapor in a tubular reactor. The heat required for the dehydrogenation is fed to the tubular reactor with a molten salt bath. The dehydrogenation is effected isothermally and in a single stage under atmospheric pressure or preferable under a subatmospheric pressure with a water vapor-ethylbenzene ratio of 1.2 to 1.5 kg of water vapor per kg of ethylbenzene. The temperature of the ethylbenzene-water-vapor mixture entering the tubular reactor is maintained 50° to 100° C. below the temperature of the molten salt bath.

Radiochemical separations in molten salts. Determination of carbon in metals by photon activation

Abstract: A systematic study of radiochemical separations of carbon in molten salts was achieved. It combined forecasting of salt mixtures from literature data and experimental work The basic three mixtures of molten salts which were studied, are the following: Pb3O4−B2O3, NaOH−NaNO3 and H2SO4−KIO4 with some additions of complexing agents Selected procedures for the determination of carbon by photon activation were issued for the following samples: Ag, Al, Cr, Fe, Mg, Mo, Ni, Si, Ti, W, Zn, Zr, AlMg, AgZn and ZnMgTe. The detection limit for carbon was 10−8 g and the accuracy from 5 to 10%. Applications to solid state science are given.

Ceramic oxide electrodes, their method of manufacture and a cell and processes for molten salt electrolysis using such electrodes

Abstract: A substantially non-consumable anode used in the production of aluminium from a cryolite-based fused bath containing alumina consists of a sintered self-sustaining ceramic oxide body of spinel structure which is made conductive by selective partial substitution, the introduction of non-stoichiometry or by doping so as to maintain the impurities in the produced aluminium at low levels. Preferred materials are partially-substituted nickel ferrite spinels.