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Bessemer process

Bessemer process (bĕs´əmər) [for Sir Henry Bessemer], industrial process for the manufacture of steel from molten pig iron. The principle involved is that of oxidation of the impurities in the iron by the oxygen of air that is blown through the molten iron; the heat of oxidation raises the temperature of the mass and keeps it molten during operation. The process is carried on in a large container called the Bessemer converter, which is made of steel and has a lining of silica and clay or of dolomite. The capacity is from 8 to 30 tons of molten iron; the usual charge is 15 or 18 tons. The converter is egg-shaped. At its narrow upper end it has an opening through which the iron to be treated is introduced and the finished product is poured out. The wide end, or bottom, has a number of perforations (tuyères) through which the air is forced upward into the converter during operation. The container is set on pivots (trunnions) so that it can be tilted at an angle to receive the charge, turned upright during the "blow," and inclined for pouring the molten steel after the operation is complete. As the air passes upward through the molten pig iron, impurities such as silicon, manganese, and carbon unite with the oxygen in the air to form oxides; the carbon monoxide burns off with a blue flame and the other impurities form slag. Dolomite is used as the converter lining when the phosphorus content is high; the process is then called basic Bessemer. The silica and clay lining is used in the acid Bessemer, in which phosphorus is not removed. In order to provide the elements necessary to give the steel the desired properties, another substance (often spiegeleisen, an iron-carbon-manganese alloy) is usually added to the molten metal after the oxidation is completed. The converter is then emptied into ladles from which the steel is poured into molds; the slag is left behind. The whole process is completed in 15 to 20 min. The Bessemer process was superseded by the open-hearth process (see steel). See also metallurgy.

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Bessemer Process

BESSEMER PROCESS


The Bessemer process was the first method for making steel cheaply and in large quantities, developed during the early 1850s. It was named after British engineer Henry Bessemer (18131898), who invented the process. The process was also developed independently in the United States by William Kelly (18111888), who received a patent for it in 1857.

Bessemer and Kelly experimented with injecting air into molten pig iron (crude iron); the oxygen in the air helped rid the iron of its impurities (such as manganese, silicon, and carbon), converting the iron to molten steel, which was then poured into molds. The process was introduced to the U.S. steel manufacturing industry in 1864. Alloys were also added to the refining process to help purify the metal. Within two decades the method was used to produce more than 90 percent of the nation's steel; it was eventually implemented throughout the industrialized world.

In the mid-1800s rich iron ore deposits were discovered in the Upper Peninsula of Michigan along Lake Superior. The discovery of the minerals and the innovation of the Bessemer process combined to create a thriving steel industry in the United States. There was a growing market for the material; railroads needed iron to make rail gauges and the new auto manufacturing industry used steel to make cars. As a result annual U.S. steel production increased by a factor of 20 between 1880 and 1910.

One of the early industry leaders was Andrew Carnegie (18351919). In 1873 Carnegie founded the nation's first large-scale steel plant at Braddock, Pennsylvania. In 1901 he sold the plant and other steel mills to the United States Steel Corporation (later to become the USX Corporation, the largest steel producer in the United States). The Bessemer process continued to be used until after World War II (19391945). The open-hearth method of refining gradually replaced it.

See also: Andrew Carnegie, Steel Industry

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Bessemer process

Bessemer process First method for the mass production of steel. English engineer Sir Henry Bessemer (1813–98) patented the process in 1856. In a Bessemer converter, cast iron is converted into steel by blowing air through the molten iron to remove impurities. Precise amounts of carbon and metals are then added to give the desired properties to the steel.

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"Bessemer process." World Encyclopedia. . Encyclopedia.com. 19 Oct. 2017 <http://www.encyclopedia.com>.

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"Bessemer process." World Encyclopedia. . Retrieved October 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/bessemer-process