Fuse-salt electrolysis

Chlorine from the Magnesium Process. Magnesium is produced by the fused salt electrolysis of MgCl2 (see Magnesium and magnesium... 

The deposition of RE metals from aqueous solutions does not work because of the highly electropositive nature of the REE. Therefore, industrial production of RE metals is carried out by fused salt electrolysis or metaHothermic reduction. 

Fused Salt Electrolysis. Only light RE metals (La to Nd) can be produced by molten salt electrolysis because these have a relatively low melting point compared to those of medium and heavy RE metals. Deposition of an alloy with another metal, Zn for example, is an alternative. The feed is a mixture of anhydrous RE chlorides and fluorides. The materials from which the electrolysis cell is constmcted are of great importance because of the high reactivity of the rare-earth metals. Molybdenum, tungsten, tantalum, or alternatively iron with ceramic or graphite linings are used as cmcible materials. Carbon is frequently used as an anode material. 

The cell for this process is unlike the cell for the electrolysis of aluminum which is made of carbon and also acts as the cathode. The cell for the fused-salt electrolysis is made of high temperature refractory oxide material because molten manganese readily dissolves carbon. The anode, like that for aluminum, is made of carbon. Cathode contact is made by water-cooled iron bars that are buried in the wall near the hearth of the refractory oxide cell. 

Fused-salt electrolysis of K2NbFy is not an economically feasible process because of the low current efficiency (31). However, electrowinning has been used to obtain niobium from molten alkaU haUde electrolytes (32). The oxide is dissolved in molten alkaU haUde and is deposited in a molten metal cathode, either cadmium or zinc. The reaction is carried out in a ceramic or glass container using a carbon anode the niobium alloys with the cathode metal, from which it is freed by vacuum distillation, and the niobium powder is left behind. 

A fused-salt electrolysis process has been demonstrated (30). Carbon dioxide is introduced to the cathode area of a melt of 60 wt % LiCl—40 wt % Li2C02 at 550°C. The carbon dioxide reacts with hthium oxide which is produced by electrolysis. Oxygen is released at the anode and carbon plates onto the cathode. The reaction requites a potential of 4.5 V. The reactions ate as follows ... 

Table 6. Tekkosha Fused-Salt Electrolysis Cells ...

Chemical Production. Electrolytic production of chemicals is conducted either by solution (water) electrolysis or fused-salt electrolysis. Fluorine, chlorine, chlorate, and manganese dioxide are Hberated from water solutions magnesium and sodium are generated from molten salt solutions. 

Fused salts Molybdenum has excellent resistance to a wide range of fused salts and has been used in the fused salt electrolysis of magnesium, platinum, thorium and uranium. In the production of pure magnesium, molybdenum is used to couple graphite electrodes electrically. Molybdenum cathodes are... 

The mechanism of boride formation is not always well known. However, many studies have sought to understand the chemical processes involved in fused-salt electrolysis. 

The fused-salt electrolysis method is not suitable for obtaining pure materials of definite stoichiometry. 

Cuomo JJ, Gambino RJ (1968) The synthesis and epitaxial growth of GaP by fused salt electrolysis. J Electrochem Soc 115 755-759... 

Yamamoto A, Yamaguchi M (1975) Epitaxial growth of ZnSe on Ge by fused salt electrolysis. Japan J Appl Phys 14 561-562... 

The first production of aluminum was by the chemical reduction of aluminum chloride with sodium. The electrolytic process, based on the fused salt electrolysis of alumina dissolved in cryolite, was independently developed in 1886 by C. M. Hall in America and P. L. Heroult in France. Soon afterwards a chemical process for producing pure alumina from bauxite, the commercial source of aluminum, was developed by Bayer and this led to the commercial production of aluminum by a combination of the Bayer and the Hall-Heroult processes. At present this is the main method which supplies all the world s needs in primary aluminum. However, a few other processes also have been developed for the production of the metal. On account of problems still waiting to be solved none of these alternative methods has seen commercial exploitation. 

F. P. Haver, D. E. Shanks, D. L. Bixby and M. M. Wong, Recovery of Zinc from Zinc Chloride by Fused Salt Electrolysis, U. S. Bureau of Mines, Rept. Invst. No. 8133,1976. 

J. C. Sehra and A. K. Suri, Refractory and Reactive Metal Extraction by Fused Salt Electrolysis, High Temperature Materials and Processes, Vol. 11, Nos. 1-4, p. 255,1993. 

T. K. Mukherjee and C. K. Gupta, Fused Salt Electrolysis for Refractory Metal Extraction and Refining, Trans SAEST, Vol. 11, No. 1, p. 127,1976. 

Fused-ring polynuclear aromatic hydrocarbons, 18 588t Fused salt electrolysis, 14 643 Fused-salt manganese metal electrolysis, 15 558-559... 

The fused salt electrolysis technique was successfully applied to the preparation, also as single crystals, of several transition metal compounds. A review on this subject was published by Wold and Bellavance (1972). A systematic treatment of several reactions and processes, was presented possibly somewhat obsolete now and with a drawback due to the presence of several impurities in the synthesis products. The preparation of the following compounds was especially discussed. 

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