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Open hearth furnaces are furnaces that are often used in the production of steel. Designed with a somewhat shallow hearth and roof that is lower than other furnace designs, the open hearth furnace creates an environment that aids in the removal of impurities from the pig iron that is used in the steelmaking process. Industrial furnaces of this type were used for a number of years as the primary method for making steel, and is still the most common approach in many areas around the world.
The actual process of operation with an open hearth furnace makes it possible to position the pig iron so that the combination of open flames and the hot air generated within the furnace can trigger the chemical activity necessary to produce the steel. Sometimes known as a reverberatory melting furnace, the flames pass over the material while the hot air aids in intensifying the heat within the hearth to the desirable level. While the essentials of this approach were used in limited applications for centuries, the development of a true open hearth furnace occurred during the middle portion of the 19th century and became the industry standard within a few decades. For the most part, the open hearth furnace remained the most viable method of steel production until the early 1970s.
One of the chief benefits of using an open hearth furnace is the ability to extract the impurities from the pig iron as it is subjected to the extreme temperatures. The end result is steel that is more durable and able to withstand greater levels of stress. Thanks to this particular approach to steelmaking, girders and other types of construction materials were produced that allowed for the creation of taller buildings as well as the construction of machinery and other devices containing steel components that could hold up under a great deal of stress and use.
Over time, the open hearth furnace has lost ground to new technologies that made it possible to remove the impurities and produce higher grades of steel, while also reducing the cost of production. Much of the reduction in production costs came about due to the development of alternative methods that were more energy-efficient, such as the electric arc furnace or the oxygen furnace. While no longer in common use around the world, the open hearth furnace is still utilized in some countries, although the production is normally on a much smaller scale than a few decades ago.