Industrial fused salt electrolysis

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. 

The following subsections discuss a few chemical processes that involve the electrolysis of aqueous solutions or fused salts. It is not intended to provide here an exhaustive treatment of the subject but rather to select a few typical cases that serve to acquaint the student with the nature, the scope, and the importance of these industries. 

Electrolytic reduction. Although perhaps not properly classified as a smelting process, the production of metals by electrolysis may be included at this juncture. Examples of the production of active metals by the electrolysis of either fused salts or aqueous solutions are included in the discussion of industrial electrochemical processes earlier in this chapter. 

Industrially, borides are prepared in various ways, including reduction of metal oxides by mixtures of carbon and boron carbide, electrolysis in fused salts, and direct combination of the elements. For research purposes, the last method is usually used. Cobalt boride, made in aqueous solution by reduction of Co2+ salts with NaBH4 is an active catalyst for reduction of various substrates.6... 

Electrolysis is employed widely in the manufacture of both metals and chemicals. For instance, the method is used to extract the metals sodium, magnesium and aluminium from their fused salts. In the chemicals industry, one of the largest processes is the electrolysis of an aqueous solution of sodium chloride (brine) for the manufacture of chlorine and caustic soda, i.e.. 

Mg is insol in cold w si sd in hot w, with which it reacts sol in mineral acids, cone HF and Amm salts insol in chromates alkali In 1808, Sir Humphry Davy reported the production of Mg in the form of an amalgam by electrolytic reduction of its oxide using a Hg cathode. In 1828, the Fr scientist A. Bussy fused Mg chloride with metallic K and became the first to produce free metallic Mg. Michael Faraday, in 1833, was the first to produce free metallic Mg by electrolysis, using Mg chloride. For many years, however, the metal remained a laboratory curiosity. In 1886, manuf of Mg was undertaken on a production scale in Ger, using electrolysis of fused Mg chloride. Until 1915, Ger remained the sole producer of Mg. However, when a scarcity of Mg arose in the USA as a result of the Brit blockade of Ger in 1915, and the price of Mg soared from 1.65 to 5.00 per lb, three producers initiated operations and thus started a Mg industry in the USA. Subsequently, additional companies attempted production of Mg, but by 1920 only two producers remained — The Dow Chemical Co (one of the original three producers) and. the American Magnesium Corp. In 1927, the latter ceased production, and Dow continued to be the sole do- mestic producer until 1941. The source of Mg chloride was brine pumped from deep wells. In 1941, Dow put a plant into operation at Freeport, Texas, obtaining Mg chloride from sea-... 

---