Re: Limestone for the Steel Industry (was. . . Kline & Culotta's book)

Anthony Thompson <thompson@...>

Philip Dove wrote:
Isn't Lime not just powdered limestone, surely it has been fired or baked so that it becomes a rather caustic alkali.
Exactly. Lime, strictly, is calcium oxide, a most vigorously hygroscopic materia. What is sold as "slaked lime" is calcium hydroxide. Limestone is a mineral, thus not exactly any chemical composition, but its fundament is calcium carbonate, which by itself is called calcite. Roasting it drives off carbon dioxide and leaves you with lime (kinda simplified explanation <g>). There is usually some silica in limestone (the more there is, usually the harder it is, and the harder to roast it to oxide), and often iron oxides or other additional minerals.
When limestone undergoes metamorphism, it becomes marble. Dolomite isn't limestone, but is calcium magnesium carbonate. Whether the magnesium is good or bad for your steel slag (the destination of the limestone, lime, or dolomite) depends on the rest of the chemistry.
One can, of course, google these terms, or look in Wikipedia.

Anthony Thompson
Dept. of Materials Science & Engineering
University of California, Berkeley

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