In 1856, Sir Henry Bessemer, an accomplished inventor and engineer, invented the Bessemer process. After gaining experience from working with the open hearth process — which involved heating a mixture of iron and scrap steel in an open hearth furnace — the engineer came up with the idea for a new and improved steelmaking technique.
But he wasn't the only one trying to advance steel production during that time. Another notable figure in this pursuit was William Kelly, an American ironmaster. Independently, Kelly discovered a similar process involving blowing oxygen through molten iron to remove impurities.
However, there were differences between Kelly's and Bessemer's approaches. Kelly's method used a tilting converter, while Bessemer introduced a stationary converter. Additionally, Bessemer's process involved blowing air directly into the molten iron, while Kelly's process used a preliminary heating step before blowing oxygen. Despite these variances, it was Kelly's work that laid the groundwork for further advancements and served as a source of inspiration for Bessemer.
Bessemer built upon Kelly's discoveries and made significant progress in perfecting the steelmaking process. His most notable invention was the Bessemer converter, a crucial component in his method. By blowing oxygen through molten pig iron in the converter, Bessemer removed impurities and was able to transform wrought iron into high-quality steel. He also introduced innovative techniques to control airflow and temperature, making large-scale steel production more efficient and practical.
And last but not least, the skilled metallurgist Robert Mushet suggested the addition of spiegeleisen, an iron alloy, to the converter. This addition significantly enhanced the quality and strength of the resulting steel, further contributing to the effectiveness of the Bessemer process.