The UK must keep a blast furnace to produce pure steel

IT'S time our political leaders steeled themselves to face some facts. It's in the news a lot these days; the Scunthorpe steel works, British steel, Chinese steel, blast furnaces, arc furnaces. But why's it important? What's the fuss? What's it all about?

- Sir Andrew Cook

Let’s start with the material. Steel does not naturally occur. It’s a metal made out of iron and iron is a metal refined from iron ore. This iron ore is dug out of the ground like coal and gold, mainly in Africa, Australia and South America. The ore is shipped to places where there are steelworks with blast furnaces. The blast furnace takes the iron ore, adds limestone and coke and sets fire to the coke. A blast of air is forced through the glowing coke, which melts the iron within the ore.

The liquid iron is collected in a huge ladle and taken to another part of the steelworks to be made into steel.

HOWEVER, this raw iron contains a lot of the element carbon, which makes it very brittle. It also contains phosphorus, which makes it more brittle still.

For these reasons iron in its original form is of little use. To make it more useful, the carbon and the phosphorus have to be reduced. This is done in a big pot called a converter, invented by British engineer Henry Bessemer. He forced air through the molten iron to burn out the carbon and phosphorus.

Later versions used pure oxygen instead of air to speed up the converting process. Special heat-resistant linings for the pot further accelerated the process.