Sodium beryllium fluoride

Sodium beryllium fluoride (Na2BeF4) is water-soluble and sodium aluminum fluoride (Na,AlF6) is water-insoluble. A part of the silicon volatilizes off as silicon tetrafluoride (SiF4), while the other part remains in the residue as silicon dioxide (Si02). Fluorination of silicon is unnecessary and it would be economical to recover all of it as silica. This is accomplished by using soda ash, i.e., sodium carbonate (Na2C03) in the reaction mixture ... 

Beryllium-Sodium Fluoride (Sodium Beryllium Fluoride), BeF2.2NaF mw 131.00 wh or grayish poisonous cryst pdr mp about 350°, bp — decompd si sol in w insol in ale. Can be prepd by heating an aqueous soln of NaF2 beryllium fiuoride(Ref 1). Used for prepn of pure Be metal... 

Sodium Beryllium Fluorides, BeF2.NaF, BeFj.2NaF.— Two sodium beryllium fluorides have been described by Marignac (1873 2) and Lebeau (1899 ii), entirely analogous to the potassium salts. They were made in a similar way by flie simple evaporation of their constituents-, and again it is the disodium salt that is obtained most ily and in definite crystals. BeFj. 

The sodium beryllium fluoride product is soluble in water and can be leached out, together with some aluminium, excess sodium silicofluoride, and small amounts of other impurities. Unfortunately a high proportion of the valuable fluorine is lost as the gaseous and highly toxic silicon tetra-fluoride, or as undissolved sodium aluminium fluoride. However, the escape of volatile silicon tetrafluoride can be prevented if a small amount of sodium fluoride is present with the sodium silicofluoride, owing to the reaction... 

After sintering and leaching out the sodium beryllium fluoride with water, beryllium hydroxide is precipitated by the addition of sodium hydroxide, i.e. 

The sodium beryllium fluoride is leached out with water after the reaction, leaving an insoluble residue of alumina and silica. 

Initial Nuclear Characteristics of Two-Region, Homogeneous, Molten Sodium-Beryllium Fluoride Reactors Fueled with... 

Fluorides are nonhygroscopic, and their melting points are higher than those of the corresponding chlorides. Besides, the fluoride reduction reactions are considerably more exothermic. The prime examples of the use of fluorides as intermediates are the reduction of uranium tetrafluoride by calcium or magnesium the reduction of rare earth fluorides by calcium, reduction of beryllium fluoride by magnesium and the reduction of potassium tantalum double fluoride by sodium. 

Copaux A method for extracting beryllium from beryl. The ore is heated with sodium flu-orosilicate at 850°C. Leaching with water dissolves the beryllium fluoride, leaving the silica and most of the aluminum fluoride as an insoluble residue. Addition of sodium hydroxide precipitates beryllium as the hydroxide. The process was invented by H. Copaux and has been in use in France since 1915 and in the United Kingdom since World War II. 

Beryllium has also been prepared2 by other methods (1) Beryllium chloride is easily reduced by sodium or potassium, but the chloride must be in the anhydrous condition and its preparation is very troublesome. (2) The Goldschmidt process yields metallic beryllium containing about 10 per cent aluminium. The application of external heat is necessary in order to raise the temperature above the melting point of beryllium. (3) Potassium beryllium fluoride mixed with sodium and heated strongly gives metallic beryllium. 

Conditions like those described in Equation 9 exist also in the reduction of beryllium fluoride or its double fluoride (90) with sodium, according to ... 

This reaction comes to a stop with the formation of the stable complex beryllium fluoride-sodium difluoride (BeF2 2 NaF) and only a part of the beryllium can thus be obtained as metal (78), Analogous conditions have been described by Lebeau in the fusion electrolysis of beryllium fluoride-monosodium fluoride (51, 78), which stops when the bath reaches the composition of beryllium fluoride-sodium difluoride. 

The optically transparent liquid-salt coolant is a mixture of fluoride salts with freezing points near 400°C and atmospheric boiling points of 1400 C. The reactor operates at near-atmospheric pressure, and at operating conditions, the liquid-salt heat-transfer properties are similar to those of water. Several different salts can be used as the primary coolant, including lithium-beryllium, sodium-beryllium, and sodium-zirconium fluoride salts. 

In practice higher fluorine and beryllium efficiencies are obtained if a small amount of sodium carbonate is added to the sodium ferric fluoride reaction, as with the silicofluoride reaction, although in the former case it is not strictly required according to the generally accepted equation. It has been... 

An alternative fluoride breakdown process for beryl was used during the 1939-45 war by the Sappi Company in Italy. This was based upon the reaction with sodium hydrogen fluoride (NaF.HF) at a temperature of about 680°C. The fluoride reagent is mixed with the ground ore and made into briquettes with a little water, ready for firing in the breakdown furnace. The reaction converts the beryllium to a complex fluoride, believed to be 3NaF.2Bep2, without fluorination of the aluminium and silicon components. 

Lebeau, in 1898, was the first to prepare beryUium electrolyticaUy fi-om beryllium fluoride mixed with sodium or potassium fluoride. Write an equation for the reaction. Speculate on the function of the alkali-metal salts. 

These billion dollar programmes developed the technology base for use of liquid salts in nuclear systems. Two experimental reactors were built and successfully operated. The aircraft reactor experiment (ARE) was the first MSR. It was a 2.5 MW(th) reactor that was operated in 1954 at a peak temperature of 860°C and used a sodium-zirconium fluoride salt. This was followed in 1965 by the molten salt breeder reactor (MSBR) Experiment, an 8 MW(th) reactor that used a lithium-beryllium fluoride salt and demonstrated most of the key technologies for a power reactor. In addition, test loops with liquid salts were operated for hundreds of thousands of hours, materials of construction were code qualified to 750°C, and a detailed conceptual design of a 1000 MW(e) MSBR was developed. Over 1000 technical reports were produced. 

K. A. Sense et al., Vapor Pressure and Equilibrium Studies of the Sodium Fluoride-Beryllium Fluoride System, US.VEC Report BMI-1186, Battelle Memorial Institute, May 27, 1957. 

Effect of substitution of sodium for Li. In the event that Li should prove not to be available in quantity, it would be possible to operate the reactor with mixtures of sodium and beryllium fluorides as the basic fuel salt. The penalty imposed by sodium in terms of critical inventory and regeneration ratio is shown in Fig. 14-8, where typical Na-Be systems are compared with the corresponding Li-Be systems. With no thorium in the core, the use of sodium increases the critical inventory by a factor of 1.5 (to about 300 kg) and lowers the regeneration ratio by a factor of 2. The regeneration penalty is less severe, percentagewise, with 1 mole % ThF4 in the fuel salt in an 8-ft-diameter core, the inventory rises from 800 kg to 1100 kg... 

Beryl ores are processes in one of two ways. They may be finely ground, sintered with sodium fluorosilicate, and the resulting beryllium fluoride leached with water or the lump ore can be fused, quenched, annealed, and the beryllium sulfate leached with sulfuric acid. In either case, the resulting solutions are purified, and beryllium hydroxide is precipitated. This may be converted to other beryllium compounds, or reduced to the metal. Beryllium metal is then generally broken into small particles that are pressed into masses with various desired shapes through powder-metallurgical methods. Alloys, beryllium metals, and BeO account for all but a small amount of beryllium used [15]. 

Beryllium is extracted from the main source mineral, the alumino-silicate beryl, by conversion to the hydroxide and then through either the fluoride or the chloride to the final metal. If the fluoride is used, it is reduced to beryllium by magnesium by a Kroll-type reaction. The raw metal takes the form of pebble and contains much residual halides and magnesium. With the chloride on the other hand, the pure metal is extracted by electrolysis of a mixture of fused beryllium chloride and sodium chloride. The raw beryllium is now dendritic in character, but still contains residual chloride. 

Fluoridizing roasting or fluorination is similar to chlorination, and is widely used in the treatment of several rare metal ores. Beryl, the most important ore of beryllium, can be opened by fusing with sodium silicofluoride at 850 °C ... 

Using the periodic table if necessary, write formulas for the following compounds (a) hydrogen bromide, (b) magnesium chloride, (c) barium sulfide, (d) aluminum fluoride, (e) beryllium bromide, (/) barium selenide, and (g) sodium iodide. 

Copaux-Kawecki An improved version of the Copaux process for extracting beryllium from beryl, which permits recovery of the fluorine. Addition of ferric sulfate to the dilute sodium fluoride solution remaining after the separation of the beryllium hydroxide precipitates sodium tetrafluoroferrate, which is then used in place of sodium fluorosilicate. 

Metallic beryllium is produced by reduction of beryllium halide with sodium, potassium or magnesium. Commercially, it is obtained primarily from its ore, beryl. Beryllium oxide is separated from silica and alumina in ore by melting the ore, quenching the solid solution, and solubilizing in sulfuric acid at high temperatures and pressure. Silica and alumina are removed by pH adjustment. Beryllium is converted to its hydroxide. Alternatively, beryl is roasted with complex fluoride. The products are dissolved in water and then pH is adjusted to produce beryllium hydroxide. 

Assay of beryllium metal and beryllium compounds is usually accomplished by titration. The sample is dissolved in sulfuric acid. Solution pH is adjusted to 8.5 using sodium hydroxide. The beryllium hydroxide precipitate is redissolved by addition of excess sodium fluoride. Liberated hydroxide is titrated with sulfuric acid. The beryllium content of the sample is calculated from the titration volume. Standards containing known beryllium concentrations must be analyzed along with the samples, as complexation of beryllium by fluoride is not quantitative. Titration rate and hold times are critical therefore use of an automatic titrator is recommended. Other fluoride-complexing elements such as aluminum, silicon, zirconium, hafnium, uranium, thorium, and rare earth elements must be absent, or must be corrected for if present in small amounts. Copper—beryllium and nickel—beryllium alloys can be analyzed by titration if the beryllium is first separated from copper, nickel, and cobalt by ammonium hydroxide precipitation (15,16). 

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