Lithium Chloride-potassium Chloride Research Articles

Detection of Off-Gassed Products From Molten Salts Using Laser-Induced Breakdown Spectroscopy.

The detection of off-gassed sodium from molten sodium nitrate (NaNO3) at temperatures between 330 °C and 505 °C and off-gassed calcium from molten lithium chloride-potassium chloride eutectic (LKE) mixtures at 510 °C with laser-induced breakdown spectroscopy (LIBS) was demonstrated. NaNO3 and LKE samples were melted in a custom-built crucible that promoted the generation of off-gassed products from the molten sample. The off-gassed products were analyzed with a LIBS system designed to probe the high-temperature environment. Na D emission lines, Na(I)588.99 nm and Na(I) 589.59 nm, were detected from the NaNO3 samples after reaching a temperature threshold, which indicated the occurrence of phase change. In LKE mixtures, the detection of Ca impurities at a concentration of 78 mg/kg was possible using the emission lines Ca(II) 393.66 nm and Ca(II) 395.85 nm. This work demonstrates the real-time monitoring capabilities of LIBS in high-temperature environments that simulate the conditions of molten salt reactors.

Uranium measurements using laser-induced breakdown spectroscopy in lithium chloride-potassium chloride salt of pyroprocessing

In pyroprocessing, uranium (U) is recovered from molten LiCl–KCl salt, and, for safeguard purposes, it is important to analyze the U and Plutonium (Pu) concentrations in a timely manner. In the present work, salt samples containing U were fabricated. The laser used in the present work was an Nd:YAG laser with a wavelength of 532 nm, a laser energy on the sample of 11.5 mJ, and a pulse repetition rate of 10 Hz. The plasma emission light was measured with an Echelle spectrometer. A total of 100 points on the sample surface were measured as the laser incident position was changed. The U and potassium (K) peaks in the spectrum were identified. Univariate and multivariate analyzes were conducted to determine the accuracy and limit of detection (LOD) of the laser-induced breakdown spectroscopy.

Kinetic Parameters and Diffusivity of Uranium in FLiNaK and ClLiK

Anodic stripping voltammetry (ASV) and cyclic voltammetry (CV) measurements at 773, 823, and 873 K were made of uranium trifluoride (UF3) in lithium fluoride-sodium fluoride-potassium fluoride eutectic (FLiNaK) and uranium trichloride (UCl3) in lithium chloride-potassium chloride eutectic (ClLiK). ASV data were used to estimate the charge transfer coefficients, exchange current densities, and activation energies of the uranium reactions. Charge transfer coefficients of both salt systems were within the range of 0.17 to 0.38. Exchange current densities in the fluoride and chloride salts were estimated within the range of 0.060 to 0.12 A cm−2. Activation energy of uranium exchange current was 16.0 kJ mol−1 in the fluoride salt and 28.9 kJ mol−1 in the chloride salt. Kinetics of charge transfer were found to be faster in FLiNaK. Analyses of the CV data suggest the electrochemical system was diffusion controlled and irreversible in the chloride and fluoride salt mixtures. Diffusion coefficients of uranium in the range of temperatures were on the order of 10−5 cm2 s−1 in both systems. Greater values of diffusivity in ClLiK are attributed to its lower density compared with FLiNaK. Activation energy of uranium diffusion in the fluoride and chloride salt mixtures were 53.4 and 89.4 kJ mol−1, respectively.

Investigating microstructural evolution during the electroreduction of UO2 to U in LiCl-KCl eutectic using focused ion beam tomography

Reprocessing of spent nuclear fuels using molten salt media is an attractive alternative to liquid-liquid extraction techniques. Pyroelectrochemical processing utilizes direct, selective, electrochemical reduction of uranium dioxide, followed by selective electroplating of a uranium metal. Thermodynamic prediction of the electrochemical reduction of UO2 to U in LiCl-KCl eutectic has shown to be a function of the oxide ion activity. The pO2− of the salt may be affected by the microstructure of the UO2 electrode. A uranium dioxide filled “micro-bucket” electrode has been partially electroreduced to uranium metal in molten lithium chloride-potassium chloride eutectic. This partial electroreduction resulted in two distinct microstructures: a dense UO2 and a porous U metal structure were characterised by energy dispersive X-ray spectroscopy. Focused ion beam tomography was performed on five regions of this electrode which revealed an overall porosity ranging from 17.36% at the outer edge to 3.91% towards the centre, commensurate with the expected extent of reaction in each location. The pore connectivity was also seen to reduce from 88.32% to 17.86% in the same regions and the tortuosity through the sample was modelled along the axis of propagation of the electroreduction, which was seen to increase from a value of 4.42 to a value of infinity (disconnected pores). These microstructural characteristics could impede the transport of O2− ions resulting in a change in the local pO2− which could result in the inability to perform the electroreduction.

Separation of strontium and cesium from ternary and quaternary lithium chloride-potassium chloride salts via melt crystallization

Separation of cesium chloride (CsCl) and strontium chloride (SrCl2) from the lithium chloride-potassium chloride (LiCl-KCl) salt was studied using a melt crystallization process similar to the reverse vertical Bridgeman growth technique. A ternary SrCl2-LiCl-KCl salt was explored at similar growth rates (1.8–5 mm/h) and compared with CsCl ternary results to identify similarities. Quaternary experiments were also conducted and compared with the ternary cases to identify trends and possible limitations to the separations process. In the ternary case, as much as 68% of the total salt could be recycled per batch process. In the quaternary experiments, separation of Cs and Sr was nearly identical at the slower rates; however, as the growth rate increased, SrCl2 separated more easily than CsCl. The quaternary results show less separation and rate dependence than in both ternary cases. As an estimated result, only 51% of the total salt could be recycled per batch. Furthermore, two models have been explored to further understand the growth process and separation. A comparison of the experimental and modeling results reveals that the nonmixed model fits reasonably well with the ternary and quaternary data sets. A dimensional analysis was performed and a correlation was identified to semipredict the segregation coefficient.

Experimental Study of Salt Bead Dissolutions in Aqueous Solvents

Bead dissolutions of several chloride compounds—lithium chloride-potassium chloride (LiCl-KCl) eutectic, lithium chloride (LiCl), strontium chloride (SrCl2), cerium chloride (CeCl3), lanthanum chloride (LaCl3), praseodymium chloride (PrCl3), and yttrium chloride (YCl3)—were performed in water at 20 °C. Additional bead dissolutions involved LiCl-KCl beads in two types of brine solvents. Each bead diameter was measured and found to change linearly with time in water. A model regression to these measured data resulted with R2 > 0.942. Results indicated dissolution was faster in water than in the brines. Calculated mass transfer coefficients were in the range of 1.00 × 10–2 mm s−1 to 2.67 × 10–2 mm s−1. Based on a Sherwood correlation, Sh = 2 + 0.0254Gr0.333Sc0.577, calculated diffusion coefficients were in the range of 10–5 mm2 s−1 to 10–3 mm2 s−1. Results implied mass transfer of the eutectic was dominated by diffusion, whereas a transition from natural convection to diffusion was inferred for the other sol...

Corrosion Behavior of Candidate Materials in Molten LiCl-KCl Salt Under Argon Atmosphere

Pyrochemical reprocessing involves the use of molten LiCl-KCl (lithium chloride-potassium chloride) eutectic salt at 773 K for the recovery of uranium and plutonium from spent metallic fuel of fast breeder reactors. The materials selected for such corrosive environments should withstand high temperatures and at the same time offer good corrosion resistance. The present work discusses the corrosion behavior of candidate materials like 2.25Cr-1Mo steel (UNS K21590), 9Cr-1 Mo steel (UNS K90941), Ni-based alloy 600 (UNS N06600), Ni-based alloy 625 (UNS N06625), and Ni-based alloy 690 (UNS N06690) in molten LiCl-KCl eutectic salt at 873 K for various durations under ultrahigh-purity argon atmosphere. Corrosion behavior of partially stabilized zirconia (PSZ) coating on candidate materials also was evaluated. Weight-loss results indicated that the corrosion resistance of the materials increased in the following order: 2.25Cr-1Mo > 9Cr-1 Mo > Ni-based alloys > PSZ coating. PSZ-coated specimens showed better corrosion resistance in molten LiCl-KCl salt when compared with uncoated specimens; however, accidental ingression of oxygen and moisture could result in premature spallation of the coating. Scanning electron microscopy (SEM) examination and grazing incidence x-ray diffraction (GIXRD) analysis of exposed Cr-Mo steels and Ni-based alloys exhibited dealloyed surfaces and corrosion product regions rich in Cr, indicating preferential leaching of Cr. The paper highlights the results of the present investigation.

A special case

SecEdVol. 2006, No. 3 OthersA special casePhil WhitehousePhil WhitehouseSearch for more papers by this authorPhil WhitehousePublished Online:28 Jan 2014https://doi.org/10.12968/sece.2006.3.602AboutSectionsView articleView Full TextView EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareShare onFacebookTwitterLinked InEmail View article FiguresReferencesRelatedDetailsCited byUranium measurements using laser-induced breakdown spectroscopy in lithium chloride-potassium chloride salt of pyroprocessing15 May 2020 | Plasma Science and Technology, Vol. 22, No. 7Is an Increase in the Minimum Retirement Age Always Desirable? The Case of Notional Defined Contribution Systems25 January 2016 | Metroeconomica, Vol. 67, No. 3L ONGEVITY S ELECTION AND L IABILITIES IN P UBLIC S ECTOR P ENSION F UNDS10 July 2013 | Journal of Risk and Insurance, Vol. 82, No. 1 1 March 2006Volume 2006Issue 3ISSN (print): 1479-7704ISSN (online): 2755-290X Metrics History Published online 28 January 2014 Published in print 1 March 2006 Information© MA Education Ltd 2006

Recycling of magnesium alloys: Chemical equilibria between magnesium-lithium-based melts and salt melts

Magnesium-lithium alloys have been equilibrated with chloride melts at 700 °C in iron crucibles. After quenching, the compositions of the metal and salt phases were determined by chemical analyses. The obtained data were evaluated according to thermodynamic principles. The following reactions were investigated: MgCl2+2Li=2LiCl+Mg (Reaction [1]), CaCl2+2Li=2LiCl+Ca (Reaction [2]), and BaCl2+2Li=2LiCl+Ba (Reaction [3]). The equilibrium of Reaction [1] is much on the right side of the reaction equation. If calcium chloride or barium chloride are added to the salt mixture (to increase the density), these chlorides are partially reduced, leading to pickup of calcium or barium, respectively, by the metal phase. Reaction [1] can be utilized in two different recycling schemes. With a magnesium chloride free lithium chloride-potassium chloride mixture, remelting of magnesium-lithium alloys is possible without loss of lithium to the slag. On the other hand, the lithium can be separated from the magnesium by conversion to lithium chloride using a magnesium chloride rich slag.

Oscillatory Behavior in Electrochemical Deposition Reaction of Polycrystalline Silicon Thin Films through Reduction of Silicon Tetrachloride in a Molten Salt Electrolyte

Abstract A new electrochemical oscillation is found for reduction reaction of silicon tetrachloride on a partially immersed single crystal n-Si electrode in a lithium chloride-potassium chloride eutectic melt electrolyte. The reduction of SiCl4, which is almost insoluble in the electrolyte, occurs mainly near the upper edge of an electrolyte meniscus on the electrode, and it is discussed that the oscillation is caused by a change in the height of the meniscus due to a change in the chemical structure (and hence the interfacial tension) of the electrode surface with progress of the silicon deposition reaction.

Anodic behavior of titanium in the presence of titanium(III) chloride in molten lithium chloride-potassium chloride eutectic melts

It is shown that the open circuit potential of a titanium electrode in TiCl 3 solutions of molten lithium chloride-potassium chloride melts behaves according to the Ti(III)/Ti(II) redox electrode potential of the reaction: Ti + 2 TiCl 3 ⇄ 3 TiCl 2. A dependence of 75 mV per a logarithmic concentration ratio of ( C Ti(III)) 2 to ( C Ti(II)) 3 was obtained. The initial dissolution rate of titanium in TiCl 3 showed a first order process with respect to the TiCl 3 concentration with a specific rate constant of 5.05 × 10 −3 min −1. The rate determination was extended from 723 to 803 K and the activation energy was calculated to be 88.68 kJ mol −1. The actual titanium dissolution rate in TiCl 3 was measured and used to verify the validity of the results obtained by the electrochemical techniques (linear polarization and Tafel methods). A correlation was developed that relates the corrosion current obtained from the Tafel methods, I corr(Tafel), to that obtained from the actual metal dissolution, I corr(w.d.). Tafel slopes for Ti dissolution were 90 mV decade −1 which gives an anodic transfer coefficient, β, of 1.55 while the cathodic Tafel slope is 100 mV decade −1 giving a cathodic transfer coefficient, a, of 0.5. A dissolution mechanism compatible with the experimental facts is proposed.

Electrochemical behaviour of titanium(II) and titanium(III) compounds in molten lithium chloride/ potassium chloride eutectic melts

The nature of the open circuit potentials of Ti and TiC electrodes in titanium(II) and titanium(III) chloride solutions, the apparent valency of the titanium ions in the melt immediately after the anodic dissolution of TiC and Ti, as well as the anodic dissolution of Ti, have been investigated in order to explain the oxidation-reduction process of titanium in lithium chloride-potassium chloride eutectic melts. It is shown that the standard electrode potential for TiC/Ti(III) exceeds that for the oxidation of Ti(II) to Ti(III). The anodic dissolution of TiC anodes give stable Ti(III) species at the standard electrode potentials the contrary to the behaviour of Ti metal anodes where the stable species are Ti(II) ions. Titanium electrodes in TiCl3 solutions of molten lithium chloride-potassium chloride melts behave according to the Ti(III)/Ti(II) redox electrode potential of the reaction: Ti+TiCl3⇌3TiCl2. An anodic dissolution mechanism compatible with all the experimental facts is proposed.

Thermodynamic properties of iron and nickel chloride solutions in molten lithium chloride-potassium chloride

The thermodynamic properties of solutions of iron or nickel chlorides in mixed molten LiCl-KCl were determined by emf measurements of FeCl{sub 2} or NiCl{sub 2} formation cells. The concentration range examined was 0.015-2 mol %. The temperature dependence of the emf between 355 and 540{degree}C was used to calculate the enthalpy and entropy of formation of dissolved FeCl{sub 2} or NiCl{sub 2}. It was shown that, in the investigated concentration range, these solutions have a nearly ideal behavior. Simple empirical equations were derived to represent the emf of these formation cells with an accuracy of about {plus minus} 1.5 mV.

Ａｌ‐Ｌｉ系合金の電解製造法の研究

Lithium chloride was electrolyzed at 700°C with a cathode of molten aluminum or molten Al-Cu-Mg-Zr alloy in a ceramic fiber contained permeated with molten lithium chloride-potassium chloride electrolyte. Electrodeposited lithium alloyed directly with the molten aluminum or molten Al-Cu-Mg-Zr alloy. Current efficiency of alloyed lithium is over ninety per cent in wide range of current density. Over current density limit, potassium deposits at the cathode, and doesn't alloy over 10ppm with aluminum. Sodium containing in electrolyte as much as 1500-2000ppm doesn't alloy over 10ppm. The mechanical properties of Al-Li-Cu-Mg-Zr alloy produced by this process were also studied.

ChemInform Abstract: ELECTROLYTIC LITHIUM CHLORIDE PRECIPITATION FROM LITHIUM CHLORIDE‐POTASSIUM CHLORIDE MELT IN POROUS LITHIUM‐ALUMINUM ANODES

Chemischer InformationsdienstVolume 15, Issue 13 Physical Inorganic Chemistry ChemInform Abstract: ELECTROLYTIC LITHIUM CHLORIDE PRECIPITATION FROM LITHIUM CHLORIDE-POTASSIUM CHLORIDE MELT IN POROUS LITHIUM-ALUMINUM ANODES C. E. VALLET, C. E. VALLETSearch for more papers by this authorD. E. HEATHERLY, D. E. HEATHERLYSearch for more papers by this authorL. JUN. HEATHERLY, L. JUN. HEATHERLYSearch for more papers by this authorJ. BRAUNSTEIN, J. BRAUNSTEINSearch for more papers by this author C. E. VALLET, C. E. VALLETSearch for more papers by this authorD. E. HEATHERLY, D. E. HEATHERLYSearch for more papers by this authorL. JUN. HEATHERLY, L. JUN. HEATHERLYSearch for more papers by this authorJ. BRAUNSTEIN, J. BRAUNSTEINSearch for more papers by this author First published: March 27, 1984 https://doi.org/10.1002/chin.198413023Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume15, Issue13March 27, 1984 RelatedInformation

The polarographic reduction wave of magnesium ion(II) in a molten LiClKCl eutectic mixture

The polarographic reduction wave of magnesium ion was confirmed in the purified lithium chloride-potassium chloride eutectic + magnesium chloride (7.20 × 10 −2 mol/l) melt kept at 450°C. The half wave potential was −2.53V vs the PtPt 2+ reference electrode, which was very close to the equilibrium potential −2.580V of MgMg 2+ already reported. The limiting current increased proportionally with the increase of magnesium chloride concentration. The relation between the current and the potential in the reduction wave of magnesium cation was expressed by the Heyrovsky — Ilkovic equation. The residual current raised in two steps due to the reduction of water introduced in the purified lithium chloride-potassium chloride-magnesium chloride melt by the addition of unpurified magnesium chloride and hydrated magnesium chloride.

Electrowinning of cerium group metals from fused chloride bath

Cerium group metals, namely, misch metal, lanthanum and cerium have been electrowon from their vacuum-dehydrated chlorides in fused sodium chloride-potassium chloride and lithium chloride-potassium chloride solvent. Temperature, cathode current density and composition of bath were optimised for high current efficiency and metal yield. In the case of lanthanum, current efficiency of 88% was achieved. The metals were free from inclusions and voids and analysed 99%+. The major non-rare earth metallic impurities were Fe, Mg and Al. The total gaseous impurities for lanthanum and misch metal were not more than 0·017%.

ChemInform Abstract: STRUCTURE AND ANODIC DISCHARGE BEHAVIOR OF LITHIUM‐BORON ALLOYS IN THE LITHIUM CHLORIDE‐POTASSIUM CHLORIDE EUTECTIC MELT. II

Chemischer InformationsdienstVolume 10, Issue 41 Physical Inorganic Chemistry ChemInform Abstract: STRUCTURE AND ANODIC DISCHARGE BEHAVIOR OF LITHIUM-BORON ALLOYS IN THE LITHIUM CHLORIDE-POTASSIUM CHLORIDE EUTECTIC MELT. II L. E. DEVRIES, L. E. DEVRIESSearch for more papers by this authorL. D. JACKSON, L. D. JACKSONSearch for more papers by this authorS. D. JAMES, S. D. JAMESSearch for more papers by this author L. E. DEVRIES, L. E. DEVRIESSearch for more papers by this authorL. D. JACKSON, L. D. JACKSONSearch for more papers by this authorS. D. JAMES, S. D. JAMESSearch for more papers by this author First published: October 9, 1979 https://doi.org/10.1002/chin.197941024AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume10, Issue41October 9, 1979 RelatedInformation

The polarographic reduction wave of magnesium ion(II) in a molten LiCl-KCl eutectic mixture

Abstract The polarographic reduction wave of magnesium ion was confirmed in the purified lithium chloride-potassium chloride eutectic + magnesium chloride (7.20 × 10 −2 mol/l) melt kept at 450°C. The half wave potential was −2.53V vs the PtPt 2+ reference electrode, which was very close to the equilibrium potential −2.580V of MgMg 2+ already reported. The limiting current increased proportionally with the increase of magnesium chloride concentration. The relation between the current and the potential in the reduction wave of magnesium cation was expressed by the Heyrovsky — Ilkovic equation. The residual current raised in two steps due to the reduction of water introduced in the purified lithium chloride-potassium chloride-magnesium chloride melt by the addition of unpurified magnesium chloride and hydrated magnesium chloride.

The oxygen electrode in fused lithium chloride-potassium chloride eutectic containing oxide ion

The oxygen evolution reaction in a fused lithium chloride-potassium chloride eutectic containing oxide ions was examined by means of the voltammetric method. The electrode reaction was polarographically reversible at platinum, rhodium and palladium electrodes. The cyclic voltammogram obtained showed that the oxidation-reduction reaction of the oxygen electrode was also reversible. The analysis of the current-potential curve revealed that the number of electrons involved in the electron transfer step was two. The gold electrode gave a different behaviour from the above electrodes. It gave two separate waves, both depending upon the oxide ion concentration. The electrode potential of the oxygen electrode, O 2− /O 2 (Pt), was measured on the basis of the voltammetric measurement. The Nernstian plot of this system was linear and the slope was in good agreement with the one theoretically presumed. The standard electrode potential was −1.173 V at 450°C vs. the standard chlorine electrode. The oxygen evolution reaction of other oxide ion donors, OH − and H 2 O 2 , was examined subsidiarily.