Melts, electrolysis

However, the physicochemical properties of nitrogen chloride give no grounds for the explanation of its stability under melt electrolysis conditions. The possibility of the formation of a chlorine derivative of carbamide according to the scheme ... 

NF3 is synthesized by the melt electrolysis of NH4F/HF mixtures, or by the fluorination of ammonia catalyzed by copper. 

The proportion of elemental lithium in the total production of lithium and lithium compounds worldwide is ca. 10%. It is exclusively manufactured by melt electrolysis of a mixture of lithium chloride (45 to 55%) and potassium chloride at 400 to 460°C in steel cells with a graphite anode and a steel cathode. The cell voltage is 6.0 to 6.5 V. The metallic lithium formed collects on the surface of the molten salt electrolyte. 

Lithium carbonate is utilized as a starting material for the manufacture of all other lithium compounds and in large quantities in the manufacture of aluminum by melt electrolysis (ca. 25% of the total lithium consumption). Lithium carbonate is also used as a flux in the glass, enamel and ceramic industries, which accounts for a further ca. 25% of lithium consumption. Glasses with high lithium content (on the basis of lithium aluminosilicate) are as a result of their low thermal expansion coefficients virtually fireproof. In psychiatry high purity lithium carbonate is utilized for the treatment of manic-depressive complaints. 

Lithium chloride Lithium chloride is manufactured by the reaction of lithium carbonate with hydrochloric acid. As a result of its high corrosivity special steels and titanium apparatus are used. The main application of lithium chloride is in melt electrolysis in the manufacture of metallic lithium. 

Manufacture of sodium by melt electrolysis of NaCI (with added CaCU and BaCU) at ca. 600"C, electricity consumption lOkWh/kg Na... 

The manufacture of elemental potassium is unimportant with a worldwide production in the early 1990 s of less than 500 t/a. It is manufactured by the reaction of molten potassium chloride with sodium at high temperatures, whereupon a potassium/sodium alloy is formed, which is fractionally distilled. Metallic potassium is obtained in a purity of > 99.5%. The formerly operated melt electrolysis of potassium hydroxide or potassium chloride is no longer operated. Potassium is utilized for the manufacture of potassium peroxide K2O2 and Na/K-alloys (reducing agent, heat carrier e.g. in the nuclear industry). 

Manufacture Metallic beryllium is either produced by reduction from beryllium fluoride with magnesium in graphite crucibles at elevated temperatures or, less commonly, by melt electrolysis of beryllium chloride. 

Two largest manufacturers of magnesium in the Western World both produce Mg by melt electrolysis (USA, Norway)... 

Liquid aluminum (99.5 to 99.9% pure) is produced in the electrolysis furnace by three layer melt electrolysis with the help of fluorine-containing fluxes or by fractional crystallization. 

Production processes other than the melt electrolysis of aluminum oxide, such as the energetically more favorable and environmentally more favorable electrolysis of aluminum chloride, have only minor industrial importance. 

Other preparative methods HI. Claims have been advanced that high purity MiggSi can be prepared by melt electrolysis of magnesium silicate. 

Other methods- CaSia can also be prepared, according to Dodero, by melt electrolysis above 1000°C using a flux. The proportions of the components are 3SiOa + SCaCOg + 6 CaFg + CaCla-... 

In contrast to titanium and zirconium, the preparation of thorium metal via reduction of the oxide with calcium (method II) acquires increased importance and rivals the reduction of the tetrachloride with sodium (method I). Melt electrolysis (method III) is another possibility. Neglecting the small oxide content (up to 1%), which in any case has never been determined precisely, the metal obtained by any of the three methods is already quite pure and contains only 0.1-0.2% of other impurities. The Th prepared by the refining process (method IV), is definitely oxygen-free and should in any case yield the purest product. 

The pure, crystalline silicides are obtained by melt electrolysis of a mixture of, for example, lOKgSiFg + TiOg at about 900°C, using an iron cathode alternately, electrolysis of TiOg dissolved in a melt of silicate may be used. 

A pre-electrolysis technique has been found effective in removing impurities such as boron from the melt. Electrolysis takes place onto a separate cathode at 950°C, for only 5 min, with only 0-5-3 per cent of potassium uranium fiuoride in the melt. ... 

Huber, K. Post, E. (1960) Preparation of niobium and tantalum by melt electrolysis. German Patent 1,092,217. 

Because of the commercial importance of uranium, a number of methods for generating finely divided chemically reactive uranium metal have been developed. Pyrophoric uranium metal powders have been prepared by thermal decomposition of uranium amalgam [21-23] or uranium hydride [24, 25]. Many methods have involved reduction of uranium oxides [26]. Other methods employed are melt electrolysis [26] and potassium reduction of (i/ -C6H5)4U [27]. 

Hevesy started as an electrochemist, since the topic of his dissertation was the production of alkali metals by melt electrolysis [12], He published several electrochemical papers on the electrolytic production of metals [13] but also on several other electrochemical topics, e.g., on the electrocapillarity [14], Nevertheless, we do not consider him as an electrochemist since he became famous as a discoverer of a new element, hafnium, and especially as a leading person in the area of radioactivity. He studied the electrochemistry of radioactive elements (Figs. 12.8,12.9, and 12.10) and used the electrochemical techniques successfully also in radiochemistry, ionic diffusion in electrolytes, and metals [15-19]. In 1913, he carried out the first radioactive tracer experiment with Friedrich Adolf Paneth in Vienna [20]. The use of tracer technique opened up new vistas also in electrochemistry. It provided a reliable method to investigate kinetics and equilibrium of electrode processes, e.g., adsorption dissolution, deposition, and underpotential deposition of metals. 

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