Cerium manufacture

Cerium is a component of misch metal, which is extensively used in the manufacture of pyrophoric alloys for cigarette lighters. While cerium is not radioactive, the impure commercial grade may contain traces of thorium, which is radioactive. The oxide is an important constituent of incandescent gas mantles and is emerging as a hydrocarbon catalyst in self cleaning ovens. In this application it can be incorporated into oven walls to prevent the collection of cooking residues. 

As ceric sulfate is used extensively as a volumetric oxidizing agent in quantitative analysis. Cerium compounds are used in the manufacture of glass, both as a component and as a decolorizer. 

Polymerization inhibitors miscellaneous, 23 383 in styrene manufacture, 23 338 Polymerization initiators alkyllithiums as, 74 251 cerium application, 5 687 peroxydicarbonates as, 74 290 Polymerization kinetics, in PVC polymerization, 25 666-667 Polymerization mechanism, for low density polyethylene, 20 218 Polymerization methods, choice of,... 

The compound cerium oxide (either Ce Oj or CeO ) is used to coat the inside of ovens because it was discovered that food cannot stick to oven walls that are coated with cerium oxide. Cerium compounds are used as electrodes in high-intensity lamps and film projectors used by the motion picture industry. Cerium is also used in the manufacturing and polishing of high-refraction lenses for cameras and telescopes and in the manufacture of incandescent lantern mantles. It additionally acts as a chemical reagent, a misch metal, and a chemical catalyst. Cerium halides are an important component of the textile and photographic industries, as an additive to other metals, and in automobile catalytic converters. Cerium is also used as an alloy to make special steel for jet engines, solid-state instruments, and rocket propellants. 

Cerium forms with iron a peculiar pyrophoric alloy which, when struck, emits showers of sparks, and which is used somewhat m the manufacture of automatic gas-hghters (28). 

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. 

Analytical data of samples of ore utilised on the commercial scale are set out on p. 119. By-products produced during the working-up of the rare earths for cerium and thorium compounds for use in the manufacture of incandescent mantles, as well as by-products from oertain tin and tungsten ores, are also available as sources of tantalum. 

Aluminum alloy - [MAGNETIC MATERIALS - THIN FILMS AND PARTICLES] (Vol 15) -cerium m [CERIUM AND CERIUM COMPOUNDS] (Vol 5) -electroless plating of [ELECTROLESS PLATING] (Vol 9) -standards and specification [MATERIALS STANDARDS AND SPECIFICATIONS] (Vol 16) -use m sulfuric acid manufacture [SULFURIC ACID AND SULFURTRIOXIDE] (Vol 23)... 

Fluorine is also used for the manufacture of sulfur hexafluoride (SF6) for high-voltage insulation and for uranium hexafluoride. Fluorine is used directly or combined with higher metals (cobalt, silver, cerium, etc.) and halogens (chlorine and bromine) for organic fluorinations and the growing production of fluorocarbons. 

When I started in a Color Quality Laboratory, I trained under a 40-year veteran to color manufacturing and control. Most of the instruction I received in my apprentice position was similar in nature to that earlier cerium-in-steel situation. More often than not, conventional wisdom and experience were right however, once in a while they were wrong. To the scientist, that is exactly when the fun begins If your... 

Misch metal is an alloy of about 50% cerium, 25% lanthanum, 15% neodymium and 10% other rare earth metals. Uses include manufacture of a pyrophoric alloy with iron and deoxidizer in metallurgical applications, getter for removal of oxygen from vacuum tubes, high strength magnesium alloys. 

In solid solutions, rare earths impart colour to the solutions due to their electronic configurations. This property has been profitably used in the manufacture of ceramic pigments which are extensively used in colouring of wall and floor tiles, table-ware and sanitary-ware. Cerium and praseodymium are extensively used in ceramics pigments. The shades that result due to the use of cerium and praseodymium are yellow, orange and green. 

The chemical composition of the washcoat belongs to the core know-how of the catalyst manufacturers. The most common washcoats contain aluminum oxides, cerium oxides and zirconium oxides as major constituents. The minor constituents... 

Uses. — Pure metallic cerium has no commercial uses, but its alloys are both interesting and capable of wide application. The most important of these is the alloy called misch metal, mixed metal, commercial cerium, or simply cerium, It is essentially a mixture of cerium, lanthanum, neodymium, and praseodymium, but as usually prepared it contains from 1-5 per cent iron and very small amounts of other elements. The most abundant constituent is cerium, which sometimes runs as high as 70 per cent or more, though generally it is about half of the mixture. The alloy is produced from the rare earth residues of monazite sand. This mineral is used in large quantities for the manufacture of incandescent gas mantles (see Thorium Uses), which usually contain 99 per cent thoria and 1 per cent ceria. The composition of various monazites is shown in Table XXVI. 

From this table it is evident that all monazite contains much more ceria than thoria and since the mantle is mainly thoria a very large part of the ceria is not needed for mantle manufacture. The residue which remains after removal of the thoria contains about 45 per cent Ce02,25 per cent La203, and 15 per cent didymia, the remainder being yttrium earths, samaria, etc. The residue represents 60-65 per cent of the original monazite. Since the total world s consumption of monazite has been estimated as being about 88,000 tons up to 1918, it is evident that the supply of cerium material has been very large. Some firms have stored enormous quantities of these rare earth salts, and others have thrown them away. The residues are transformed to the chlorides, which are carefully dehydrated to prevent the formation of basic salts. The purity of the chlorides is not important, but the phosphorus and sulfur content must be low, and iron and aluminium should not be present in more than small amounts. A mixture of the... 

Cerium carbide and nitride have been tried as filaments for incandescent lamps.2 Pure cerium nitrate is used in the manufacture of gas mantles. The reducing action of cerous compounds is used for producing a variegated effect in dyeing fabrics. The salts of cerium are used for making aniline black and as a base for the alizarin group of dyestuffs. 

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