Open-Hearth Furnace

An open-hearth furnace is an industrial furnace in which excess carbon and other impurities are burnt out of pig iron to produce steel, using regenerative preheating in which brick-filled flues capture heat from exhaust gases and return it to the incoming fuel and air. The engineer Carl Wilhelm Siemens developed the regenerative furnace concept in the 1850s, and the French engineer Pierre-Emile Martin licensed the design from Siemens in 1865 and was first to apply it successfully to steelmaking, giving the resulting method its common name, the Siemens-Martin process. The open-hearth furnace displaced the faster but less controllable Bessemer process through the late nineteenth and much of the twentieth century because it allowed closer control of the steels composition and could recycle scrap metal, before most furnaces were decommissioned by the early 1990s in favor of basic oxygen and electric arc furnaces.