Journal Article

Fusibility Diagrams of Beryllium Fluoride–Alkali-Metal Chloride Salt Mixtures

Krylosov, A. V., Polovov, I. B., Rebrin, O. I.

2023

Overview

Beryllium-containing halide melts can be used for the electrolytic manufacturing and refining of beryllium and for reprocessing spent nuclear fuel. Data on the melting temperatures of salt mixtures are of importance for the organization of manufacturing processes using them. The complexity of researching salt systems containing beryllium fluoride is related to a number of factors, which include the hygroscopicity of a salt, corrosion activity with respect to construction materials, and salt vapor toxicity. In this relation, all preparation operations are performed in an argon atmosphere using a glove box. Differential thermal analysis (DTA) of samples is also performed in a dry pure argon atmosphere. Platinum and beryllium oxide crucibles are used. These materials exhibit the best corrosion resistance against the molten salt media under study. The fusibility diagrams of beryllium fluoride with alkali-metal (Li, Na, K, Cs) chlorides are reported; they are based on DTA and X-ray diffraction data. Coordinates of eutectic points are determined. In the beryllium fluoride range concentration from an individual alkali-metal chloride to the corresponding eutectic, the measuring results are represented in the form of approximating polynomials of the concentration dependence of the melting temperature of the BeF 2 –MCl (M = Li, Na, K, Cs) systems. The fusibility of salt mixtures of lithium and potassium chloride eutectic with beryllium fluoride is studied. The most low-melting mixture among the compositions under study contains 35 mol % beryllium fluoride and melts at 331°C. The absence of ternary compounds in the systems is shown. To identify phases, X-ray diffraction analysis is used; it shows the presence of corresponding alkali-metal chlorides in the solid phases of the systems. The presence of beryllium fluoride is determined using a characteristic absorption peak in infrared spectra. A unique method is used for the distillation of beryllium fluoride prepared by the decomposition of ammonium fluoroberyllate. In view of the glass-forming ability of beryllium fluoride, data on the melting temperatures of salt mixtures enriched in the component are evaluative.

• Publisher: Pleiades Publishing,Springer Nature B.V
• Subject: Alkali metals / Argon / Beryllium / Beryllium fluorides / Beryllium oxide / Cesium / Chemistry and Materials Science / Cooling / Corrosion resistance / Crucibles / Differential thermal analysis / Eutectics / Fluorides / Fusibility / Infrared spectra / Lithium / Manufacturing / Materials Science / Melting / Melts / Metal chlorides / Metallic Materials / Mixtures / Molten salts / Nuclear fuel reprocessing / Polynomials / Potassium / Sodium / Solid phases / Spent nuclear fuels / Temperature / Temperature dependence / X-ray diffraction