Making Iron in a Blast Furnace

Ironmaking is the quintessential Birmingham industry. The raw materials for making iron - iron ore, limestone, and coal - are available in abundance in the Birmingham area,
and for some ninety years men turned these materials into pig iron at Sloss. The heart of Sloss operation was a pair of large 400-ton blast furnaces.
A blast furnace is a cylindrical steel vessel, lined with heat-resistant brick. Iron ore, limestone, and coke (which is made from coal) are charged into the top of the furnace,
while super-hot air is blasted upward from the bottom of the furnace. The blast of air burns the coke, releasing gases that react with the iron ore. The limestone acts as a flux,
or cleansing agent, removing impurities from the ore. Freed of impurities, the molten iron collects in the bottom of the furnace, where it can be drawn off. The impurities,
known as slag, are also molten, but are lighter than the iron and float on top of it. The slag is also drawn off periodically.

In addition to the furnaces themselves, an ironmaking plant consists of a large number of auxiliary machines and structures: blowers to pump the blast of air;
stoves to heat the air; boilers to produce steam to drive equipment; and a network of pipes that carry steam, water, and gas.