Page 60 - FOUNDATIONS FOR LIFE; EXPLORING GOD’S UNIVERSE

Science Y5 – God’s Amazing Matters – lesson 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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