The Bessemer process was the first inexpensive industrial process for the mass-production of steel from molten pig iron prior to the open hearth furnace. The key principle is removal of impurities from the iron by oxidation with air being blown through the molten iron. The oxidation also raises the temperature of the iron mass and keeps it molten.
Related decarburizing with air processes had been used outside of Europe for hundreds of years, but not on an industrial scale. One such process has existed since the 11th century in East Asia, where the scholar Shen Kuo describes its use in the Chinese iron and steel industry. In the 17th century, accounts by European travelers detailed its possible use by the Japanese.
The modern process is named after its inventor, the Englishman Henry Bessemer, who took out a patent on the process in 1856. The process was claimed to be independently discovered in 1851 by the American inventor William Kelly, though there is little to back up this claim.
The process using a basic refractory lining is known as the "basic Bessemer process" or "Gilchrist-Thomas process" after the discoverer Sidney Gilchrist Thomas