Furnace, Open Hearth

A furnace for melting metal in which the bath is heated by the convection of hot gases over the surface of the metal and by radiation from the roof. Until the second half of the 20th century, most of the world steel was produced in the open-hearth furnace. By the middle of the 20th century, the open-hearth process was surpassed by other technologies. The last open-hearth furnaces in North America were bricked up in the 1980s.