HISTORY OF STEEL – The Huntsman and Bessemer Breakthroughs

Steel Production process -Benjamin Huntsman Vs Henry Bessemer

Two breakthroughs in Europe put the continent on the map of steel production. England was never the same again. There are known as the Huntsman and Bessemer Breakthroughs.

Benjamin Huntsman Process

Ever since steel production began, England struggled to stay at par with the rest of the world. The metalworkers of the country came close several times but were never able to make the perfect steel. This annoyed Sheffield-based clockmaker, Benjamin Huntsman, who continuously experimented with different ways of smelting iron ore. Finally, he came up with a process of using a clay crucible for smelting, much like the ancient Indian technique. However, Huntsman used roasted coal instead of charcoal and heated the mixture of iron and carbon over coal beds.

Huntsman’s process produced uniform, stronger, and less brittle ingots, which vastly helped him in fabricating the delicate clock springs. This process also fostered unprecedented growth of steel production in England. Sheffield became the national hub of steel production. The world’s first fair, the Great Exhibition of the Works of Industry of All Nations, was held in London in 1851. Cast iron and glass used to build the Crystal Palace for the global event caught everyone’s attention. Everything that could be created from the metal—lampposts, water fountains, locomotives, steam engines—was displayed. It was the first of its kind exhibition that the world had witnessed.

Henry Bessemer Process

A British engineer, Henry Bessemer was known for many inventions, namely a typesetting machine keyboard, brass-based gold paint, and a sugarcane crusher, among other things. During the Crimean War in the 1850s, the artillery shell that he built got rendered useless by the brittle cast-iron cannons. The solution was steel, and Bessemer started finding cheaper ways to produce large quantities of steel. During the experimentation, Bessemer decided to use a container instead of the usual trench to collect the pig iron. He then blasted air through vents at the bottom, which caused chaos in the form of sparks and flames. The residue at the end was pure iron with zero carbon. This method could be used to easily produce high-quality steel, as the carbon bonded with the oxygen from the bellows, resulting in pure iron.

The machine Bessemer used for this process was called the Bessemer Converter, an egg-shaped container with solid steel on the outside and linings of clay on the inside. There was a small opening at the top for the flames and sparks. However, Bessemer’s method had one drawback—it made use of iron with little amounts of phosphorus, whereas most iron ores had high phosphorus content. Consequently, the Bessemer Converter ended up producing brittle steel. This problem got fixed by a 25-year-old chemist, Sidney Gilchrist Thomas, two decades later. Thomas replaced the clay lining with lime, which did the magic. The lining reacted with phosphorus, which made the machine churn out five tons of steel in 20 minutes, compared to Huntsman’s crucible which produced only 60 pounds of steel in 15 days.

Further read: How A-one steel group maintain high quality