Bessemer steelworks

This model was in the teaching galleries of the École des Mines until their refurbishment in 1902. Worked by articulated levers, it shows the manipulations required to produce steel using the process developed by Henry Bessemer in 1855. The molten pig iron, heated in a kind of retort called the converter, has a powerful jet of oxygen blown through it to decarburise and purify it. The impurities are evacuated either as gases or form a solid residue called slag. At the end of the process, called the ‘blow’, the molten iron is recarburised and other elements are added to obtain the desired type of steel. The converter is then tipped to pour the molten iron into crucibles. The Bessemer process, the first economical method for mass-producing steel, was replaced by the Martin process then by electric furnaces in the 20th century.