Mischmetal

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Mischmetal (from German: Mischmetall - "mixed metals") is an alloy of rare earth elements in various naturally-occurring proportions. It is also called cerium mischmetal, rare earth mischmetal or misch metal. A typical composition includes approximately 50% cerium and 45% lanthanum, with small amounts of neodymium and praseodymium. Its most common use is in the "flint" ignition device of many lighters and torches, although an alloy of only rare-earth elements would be too soft to give good sparks. For this purpose, it is blended with iron oxide and magnesium oxide to form a harder material known as ferrocerium.

Mischmetal is used in the preparation of virtually all rare earth elements. This is because such elements are nearly identical in most chemical processes, meaning that ordinary extraction processes do not distinguish them. Highly specialized processes, such as those developed by Carl Auer von Welsbach, exploit subtle differences in solubility to separate mischmetal into its constituent elements, with each step producing only an incremental change in composition. Such processes later informed Marie Curie in her search for new elements.

Mischmetal is widely applied in steel foundries for making FeSiMg alloy and it is used to remove free oxygen and sulfur by forming stable oxysulfides and by tying up undesirable trace elements, such as lead and antimony.

Mischmetal can be further processed to various shapes of ingots, pieces, wires, slabs, rods, and discs.

[edit] External links

• The Wooden Periodic Table Table - Mischmetal