BESSEMER PROCESS

The Bessemer process was the first method for making steel cheaply and in large quantities, developed during the early 1850s. It was named after British engineer Henry Bessemer (1813–1898), who invented the process. The process was also developed independently in the United States by William Kelly (1811–1888), who received a patent for it in 1857.

Bessemer and Kelly experimented with injecting air into molten pig iron (crude iron); the oxygen in the air helped rid the iron of its impurities (such as manganese, silicon, and carbon), converting the iron to molten steel, which was then poured into molds. The process was introduced to the U.S. steel manufacturing industry in 1864. Alloys were also added to the refining process to help purify the metal. Within two decades the method was used to produce more than 90 percent of the nation's steel; it was eventually implemented throughout the industrialized world.

In the mid-1800s rich iron ore deposits were discovered in the Upper Peninsula of Michigan along Lake Superior. The discovery of the minerals and the innovation of the Bessemer process combined to create a thriving steel industry in the United States. There was a growing market for the material; railroads needed iron to make rail gauges and the new auto manufacturing industry used steel to make cars. As a result annual U.S. steel production increased by a factor of 20 between 1880 and 1910.

One of the early industry leaders was Andrew Carnegie (1835–1919). In 1873 Carnegie founded the nation's first large-scale steel plant at Braddock, Pennsylvania. In 1901 he sold the plant and other steel mills to the United States Steel Corporation (later to become the USX Corporation, the largest steel producer in the United States). The Bessemer process continued to be used until after World War II (1939–1945). The open-hearth method of refining gradually replaced it.