Page 55 - FOUNDATIONS FOR LIFE; EXPLORING GOD’S UNIVERSE

Science - Y5 – God’s Amazing Matters – week 16

IRON TO STEEL

If you had to pick a few technologies that have had a tremendous effect on modern society, the refining of
iron and steel would have to be somewhere near the top of the list. Iron and steel show up in a huge array of
modern products. Cars, tractors, bridges, trains (and their rails), tools, skyscrapers, guns, ships -- even the
common steel can -- all depend on iron and steel to make them strong and inexpensive.

Have you ever wondered how people refine iron and steel? You probably have heard of iron ore, but how is it
that you extract a metal from a rock?

Creating Iron
All of the iron ores contain iron combined with oxygen. To make iron from iron ore, you need to eliminate the
oxygen to create pure iron.

The most primitive facility used to refine iron from iron ore is called a bloomery. In a bloomery, you burn
charcoal with iron ore and a good supply of oxygen (provided by a bellows or blower). Charcoal is essentially
pure carbon. The carbon combines with oxygen to create carbon dioxide and carbon monoxide (releasing lots of
heat in the process). Carbon and carbon monoxide combine with the oxygen in the iron ore and carry it away,
leaving iron metal.

In a bloomery, the fire does not get hot enough to melt the iron completely, so you are left with a spongy mass
containing iron and silicates from the ore (the bloom). By heating and hammering the bloom, the glassy
silicates mix into the iron metal to create wrought iron. Wrought iron is tough and easy to work, making it
perfect for creating tools in a blacksmith shop.

The more advanced way to smelt iron is in a blast furnace. A blast furnace is charged with iron ore, charcoal or
coke (coke is charcoal made from coal) and limestone (CaCO3). Huge quantities of air blast in at the bottom of
the furnace. The calcium in the limestone combines with the silicates to form slag. At the bottom of the blast
furnace, liquid iron collects along with a layer of slag on top. Periodically, you let the liquid iron flow out and
cool.

The liquid iron typically flows into a channel and indentations in a bed of sand. Once it cools, this metal is
known as pig iron.

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