What is the Bessemer Process?

The Bessemer process is a method of steel production named for British inventor Sir Henry Bessemer. During the Bessemer process, iron workers inject air into molten steel to remove carbon and impurities. After the Bessemer process was introduced in the 1850s, steel refining and production increased dramatically. Modern steel manufacturing uses a similar technique, but the process has been refined over the years to create high-quality steel with very few impurities.

Steel manufacturers use a special furnace, known as a Bessemer converter, to produce steel using this technique. They place iron in the furnace and melt it to produce a molten liquid, then use a high-powered blower to pass air through the liquified iron. As the air passes through, oxygen molecules within the air interact with minerals and carbon molecules in the metal. As the air exits the molten iron, it brings the carbon and other particles with it in the form of gas or slag. The remaining iron can then be poured into molds to form steel objects.

Using the Bessemer process, manufacturers were able to produce better quality steel than was previously possible. The resulting steel was stronger and more durable, allowing larger and longer-lasting structures to be built. This process also helped manufacturers produce steel more quickly, and at a lower cost than with previous techniques. For more than a century, the Bessemer process became the most popular method of mass steel production, and much of Bessemer's techniques live on in modern industry.

The steel produced using the Bessemer process has an enormous impact on warfare and industry. In fact, the Crimean War was a major source of motivation for Bessemer to develop his famous refining technique. During the war, Bessemer sold artillery shells that tended to be brittle and of poor quality. By injecting air into iron during the refining process, Bessemer was able to create strong shells that were in high demand during the war, and could be produced quickly to keep up with military orders.

While Henry Bessemer is often credited as the sole developer of this process, the Bessemer process history actually dates back thousands of years to ancient China. Many believe the Chinese were the first to use this method of steel production, but never relied on this technique for mass production. A similar process was patented by American William Kelly in 1855. Before Kelly could market his new process, he went bankrupt and sold his patent to Bessemer, who lent his name to this vital industrial technique.