Spiegeleisen (literally "mirror-iron", —
mirror or
specular; Eisen—
iron) is a
ferromanganese alloy containing approximately 15%
manganese and small quantities of
carbon and
silicon. Spiegeleisen is sometimes also referred to as
specular pig iron,
Spiegel iron, just
Spiegel, or
Bisalloy.
Usage
Historically, this was the standard form in which manganese was traded and used in
steel making. Manganese is useful in steel manufacture because it binds with
phosphorus,
sulfur, and
silica, removing them (to a degree) from the iron. It was much used in conjunction with the
Bessemer process both to introduce carbon and manganese, and also to reduce impurities.
Manufacture
In the 19th-century spiegeleisen was made either by mixing iron ores with appropriate levels of manganese and smelting them directly, or by adding
pyrolusite or
manganite to previously smelted iron in a
cupola furnace.
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See also
