Lighter flints

Lanthanum is found in rare-earth minerals such as cerite, monazite, allanite, and bastnasite. Monazite and bastnasite are principal ores in which lanthanum occurs in percentages up to 25 percent and 38 percent respectively. Misch metal, used in making lighter flints, contains about 25 percent lanthanum. 

At the beginning of the twentieth century, the incandescent mantle, utilising the candoluminescence of a mixture of thorium (95% weight) and cerium oxides was developed. The pyrophoricity of rare-earth metals led to the invention of the lighter flint made through the alloying of iron and mischmetal. Since that time, numerous other appHcations have developed to coincide with the availabiUty of the rare-earth compounds on an industrial scale and having a controlled purity. 

On a fresh surface the metal has a steely lustre but rapidly tarnishes in air as a result of surface formation of oxide and carbonate species. For protection against oxidation the metal is usually stored in a light mineral oil. When made finely divided, eg, on being cut, it can be strongly pyrophoric, and, for this reason is used, as the ferro-alloy mischmetal, in lighter flints and ordnance. Cerium reacts steadily with water, readily dissolves in mineral acids, and is also attacked by alkafl it reacts with most nonmetals on heating. 

Lighter Flints and Getters. Traditionally the item most widely associated with cerium has been the pyrophoric iron-mischmetal (- 0%) alloy for lighter flints, in limited use in the 1990s. Similar low vapor pressure reactive alloys based on cerium, such as Th2Al-MM, can also be used as getters for electronic equipment and vacuum tubes (see Electronic materials Vacuumtechnology). 

Zirconium. While almost any metal in the finely divided state exhibits pyrophoric properties, a few metals when abraded emit a shower of sparks of sufficient temp to ignite hydrocarbon vapors. Cerium is the best known metal of this kind for commercial purposes, such as gas lighter flints. For military purposes Zr is the most used. It has found applications in HE and armor-piercing incendiary ammo, the lining of shaped-charge rounds, and in incendiary cluster bombs (Ref 7, pp 100-01)... 

A commercial mixture of several of the rare-earth elements is called didymium (Di). It is neither an element nor a compound, but is used to name the mixture of oxides and salts of most of the rare-earth elements that are extracted from the ore monazite. Another unique substance, called misch metal, is an alloy of iron and several rare-earth elements (La, Ce, and Pr). This mixture is pyrophoric, which means it sparks when scratched. This is why it is used for cigarette-lighter flints. 

It is used to manufacture safety goggles that filter out strong yellow light (used in welding, for example). Misch metal uses about 5% Pr in the manufacture of cigarette lighter flints. 

An interesting stage in the development of primer mixes was the use of pyrophoric metal alloys, first patented in 1936 and improved in 1964. These rare earth alloys, as used in cigarette lighter flints, give a shower of sparks when lightly scraped. A typical pyrophoric alloy is misch metal, which has the following approximate composition cerium 50%, lanthanum 40%, other rare earth elements 3%, and iron 7%. 

Some uses of the lanthanides, such as in certain steel alloys or as cigarette lighter flints, require no separation of the metals as obtained from certain ores. In other applications, such as phosphors for television screens, medical immunoassays, X-ray photography, and, of course, the study of their chemistry, the individual elements must be separated.7... 

Ca Lighter flints, lights, plastics stabilizer US, Can., S. Amer., Asia... 

Ce Lighter flints, ceramic capacitors, magnets China, US, Aus., Ind. 

Lanthanide alloys These alloys are used in cigarette lighter flints, magnesium alloys, and ferrous alloys. 

Use Lighter flints, ferrous and nonferrous alloys, cast iron, aluminum, nickel, magnesium and copper alloys, getter in vacuum tubes, magnetic alloys. 

This is added to steel to improve its strength and workability. Small amount of misch metal is also used as lighter flints. 

Lanthanum has also found modest uses. Its oxide is an additive in high-quality optical glasses to which it imparts a high refractive index (sparkle) and has been suggested for a variety of catalytic uses. Mischmetal , an unseparated mixture of lanthanide metals containing about 25% La, is used in making lighter flints, and more importantly in the production of alloy steels, (p. 1232). 

OTHER COMMENTS used in the manufacture of ceramics, glass, and porcelains used in the synthesis of pigments, dyes, and water repellants use as abrasive and polishing materials use as an igniter in manufacture of explosives and other detonators, photoflash bulbs, and lighter flints useful in the manufacture of skin ointments and antiperspirants also used as a deoxidizer, denitrifier, and desulfurizer in iron and steel manufacture. 

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