Goldschmidt reduction process

GOLDSCHMIDT REDUCTION PROCESS. Reaction of oxide), of various metals with aluminum lo yield aluminum oxide and the free metal. This inaction has been used to produce certain metals, e g. chromium and zirconium, from oxide ores and it is also used in welding (iron oxide plus aluminum giving metallic iron and aluminum oxide, plus considerable heat). (Thermite process. ... 

Though usually prepared in the metallic condition by Goldschmidt s process, molybdenum may also be obtained by the reduction of the oxide, sulphide, or halide, by treatment under suitable conditions with carbon, hydrogen, or other reducing agent by an electrolytic method or by heating the nitride in vacuo. 

The co-reduction process has been developed by H.G. Domazer and coworkers at Goldschmidt in Essen, Germany. Similar to the reduction-diffusion process they started with a rare earth oxide and not with a rare earth metal. In contrast to the modified (technological) reduction-diffusion process (see McFarland, 1973) C03O4 is used deliberately in order to achieve a strongly exothermic reaction. Therefore the rare earth oxide and the Co oxide are reduced simultaneously. The summary equation of the process is given below ... 

One method of preparation consists in a modification of the Goldschmidt process. Niobium pentoxide is mixed with an alloy of the rare earths, called mixed metal, obtained in the manufacture of thorium nitrate, and consisting roughly of 45 per cent, of cerium, 20 per cent, of lanthanum, 15 per cent, of didymium, and about 20 per cent, of other rare-earth metals. The reaction is carried out in a magnesia-lined crucible, and is started with a firing mixture of barium peroxide, potassium chlorate, and aluminium powder. Considerable evolution of heat takes place and the reduction is extremely rapid a button of niobium is obtained 4 which, however, is not pure. 

The general method of producing a metai by reduction of its oxide by aluminum is called the Goldschmidt process or aluminothermic process Fig. 251.) Metallic chromium is also made by electrolytic reduction of compounds, usually chromic acid in aqueous solution. 

By reduction of the oxide by the Goldschmidt process. This produces a metal 98-99 per cent pure, containing small percentages of iron and silicon as impurities, but quite free from carbon,... 

Figure 26 also shows another, similar process developed by the Th. Goldschmidt AG in Germany (Domazer 1974). This co-reduction or KOR method introduces a portion of the 3d-transition element (Co, etc.) also as an oxide, the rest as metal powder. This provides more internal heat in the reacting mass. Also, the reaction vessel is evacuated and the calcium vaporized. No hydrogen is involved. The reaction is represented by the following equation ... 

Goldschmidt process A process for extracting certain metals from their oxides by reduction with aluminum, named for German chemist Hans Goldschmidt (1861-1923), who discovered it. See thermite. 

Aluminum metal is also used to produce other metals. The Goldschmidt process is a method of preparing a metal by reduction of its oxide with powdered aluminum. Chromium metal is obtained this way the reaction is highly exothermic, because of the large negative heat of formation of AI2O3 ... 

Goldschmidt process a method of preparing a metal hy reduction of its oxide with powdered aluminum. (22.4)... 

Iodine concentration in the atmosphere generally diminishes with increasing distance from the oceans. This reduction consequently reduces the amount of iodine transferred to inland soils by precipitation scavenging and dry deposition. The period of exposure of the soil to these processes also affects the iodine deposit. Hence, the concentration of iodine is generally lower in young postglacial soils, particularly in their deeper horizons (Goldschmidt, 1954). 

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