Chemicals · Vol. IV|Bessemer converter|1856

Bessemer converter

1856

Before Bessemer, steel was made in small crucibles. His converter was a tilting pear of iron that blew cold air through a molten charge. The carbon burned out in minutes with a spectacular flame. Output jumped from kilograms to tons. The industrial city is, among other things, a steel-making machine.

Henry Bessemer; independently William Kelly · England

Bessemer converter — Original plate drawn for this atlas. Not a photograph of a museum object or a copyrighted portrait.

How the mechanism is arranged

Air blown through molten pig iron burns out carbon. Steel in minutes, not days.

How it works

Charge molten pig iron into a vessel lined with refractory.
Blow air (later oxygen) through the melt; impurities oxidize.
Stop at the right carbon content and pour into ingot molds.

Why it mattered

Collapsed the price of structural steel.
Made long-span bridges and high buildings ordinary.
Fed the appetite of railways and shipyards.

What it unlocked

For further study

Bessemer, Sir Henry Bessemer, F.R.S. An Autobiography. Inventor’s account.
Science Museum Group. Converter objects.

Check

Why did blowing air through iron remove carbon?