Steel is produced from iron ore or scrap. Iron ore is a mineral aggregate that can be converted economically into iron. The quality of the iron ore is mainly determined by its composition; a high iron content and low sulphur and phosphorus contents are favorable. Iron ore can be found all over the world, but its iron content varies.
Steel scrap has been selectively collected for several decades and is recycled as a valuable raw material for steel production.
In the steel production, following stages are identified: production of pig iron; production of liquid steel; hot rolling and cold rolling; applying a metallic and/or organic coating.
There are two main processes for producing steel: by means of a blast furnace (= indirect reduction) in combination with a converter, or by means of an electric furnace. In the former process, iron ore is the main raw material. In an electric furnace, scrap iron is used and occasionally also sponge iron. Sponge is an intermediate product, which is produced from iron ore by means of direct reduction (= DRI or directly reduced iron) and that is then further reduced and smelted in an electric furnace.
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