Metallurgy - 10: The Making of Steel , Blast Furnace
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Steel, in its most basic form, is a combination of Iron and Carbon. Iron is a mineral mined from large deposits in the earth's crust and carbon is one of the most common of earth's elements.

To produce steel, the first step is to make what is called pig iron. Alternating layers of iron ore, limestone (a mineral used to purify the mixture), and coke (coal that has been prepared specially for this process) are poured into a blast furnace. Hot air at 1200 degrees F is then blasted through the exhaust vent to create the combustion process. The coke then burns the mixture at 3000 degrees F and two reactions occur. The first reaction is when the carbon from coke and the oxygen from the air combine to liberate the metallic iron and make it liquid, directing it to the bottom of the furnace. The second reaction is when the limestone attracts the impurities. These impurities float to the top of the melted pig iron and is siphoned off as slag. Every few hours, the melted pig iron is removed from the bottom of the furnace and further processed.

Pig iron contains 4 to 5% carbon which makes it much too brittle to be used as is. Reducing the extra carbon in the pig iron will convert it to steel. This process is called "refining". Just as crude oil is refined into gasoline or kerosene pig iron is refined into steel.

With the early iron making process molten metal was tapped from the bottom of the furnace and allowed to flow down a narrow stream and into sand molds. These molds were called "piglets" because the arrangement looked something like suckling pigs. Thus the name "pig iron" even today. R.S.
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label: ductility, elasticity, hardness, rockwell, brinell, malleabliity, toughness, fatigue, blast furnace, oxygen furnace, electirc furnace, alloy, alloying, aluminum