Converter (metallurgy)
The first converter was invented by Sir Henry Bessemer in 1856. He built a pear-shaped large vessel with nozzles (tuyeres) for air in the bottom. Hot molten pig iron from blast furnace was poured in the converter, and then air was pumped in at the bottom with high pressure. The result was a loud noise and a flame of up to 20 metres off the mouth of the converter. After ten minutes all the pig iron had become steel. The Bessemer converter was the first successful reactor on converting pig iron into steel, and the era of steel began. Steel was now plentiful and cheap.