Open Hearth Furnace
Open hearth furnaces are one of a number of kinds of furnace where excess carbon and other impurities are burnt out of pig iron to produce steel. Since steel is difficult to manufacture owing to its high melting point, normal fuels and furnaces were insufficient and the open hearth furnace was developed to overcome this difficulty.
In 1865, the French engineer Pierre-Émile Martin took out a license from Siemens and first applied his regenerative furnace for making steel. Their process was known as the Siemens-Martin process, and the furnace as an "open-hearth" furnace. Most open hearth furnaces were closed by the early 1990s, not least because of their slow operation, being replaced by the basic oxygen furnace or electric arc furnace.
While arguably the first primitive open hearth furnace was the Catalan forge, invented in Spain in the eighth century, but it is usual to confine the term to certain nineteenth century and later steelmaking processes, thus excluding bloomeries (including the Catalan forge), finery forges, and puddling furnaces from its application.
Read more about Open Hearth Furnace: Open Hearth Process, History
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