- Key People:
- Henry Bessemer
- John Fritz
- Alexander Lyman Holley
Bessemer process
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What is the Bessemer process?
The Bessemer process was the first inexpensive method for mass-producing steel from molten pig iron. Independently discovered by Henry Bessemer and William Kelly in the 1840s and patented by Bessemer in 1856, the process forces air through molten iron to oxidize impurities, converting them into separable slag. Robert Forester Mushet's addition of carbon, manganese, and iron alloy restores carbon content and neutralizes sulfur. The resulting low-cost steel revolutionized construction and replaced iron in railroads and other uses.
The Bessemer converter is a cylindrical steel pot lined with a siliceous refractory. Air is blown through openings near the bottom, creating oxides that become slag. The Thomas-Gilchrist converter addressed the issue of phosphorus in iron ore by using a basic lining like burned limestone.
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Who invented the Bessemer process and when?
The Bessemer process, the first method for mass-producing steel, was developed independently by Sir Henry Bessemer in England and William Kelly in the United States. Kelly began experimenting with removing impurities from pig iron using an air blast as early as 1847. Bessemer developed and patented the same process in 1856. The Bessemer process revolutionized building construction and provided steel to replace iron in railroad rails and other uses.
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How does the Bessemer process work to make steel?
The Bessemer process revolutionized steel production by enabling mass production. William Kelly and Henry Bessemer both conceived it independently. The process involves injecting an air blast into molten pig iron to remove impurities. The air's oxygen reacts with the impurities, forming oxides that separate as slag, while the heat from these reactions maintains the mass's temperature, preventing solidification. Robert Forester Mushet's addition of a carbon, manganese, and iron alloy restores the steel's carbon content and neutralizes remaining impurities like sulfur. The Bessemer process was a crucial step forward, even though other methods are used today.
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Why was the Bessemer process important to industry?
The Bessemer process was important to industry because it was the first method for mass-producing steel. This innovation in construction led to important advances, including the replacement of iron with steel in railroad rails and enabling the construction of skyscrapers. The resultant volume of low-cost steel revolutionized building construction.
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What were the main advantages of the Bessemer process compared to older methods?
The Bessemer process was the first method for mass-producing steel, which offered advantages over older methods. It enabled the production of steel ingots in a matter of minutes, ready for forging or rolling. The resultant low-cost steel quickly revolutionized building construction and replaced iron in railroad rails and other uses.
The original Bessemer converter could not effectively remove the phosphorus found in British and European iron ore. This problem was later solved by the invention of the Thomas-Gilchrist converter.
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How did the Bessemer process impact society and the growth of cities?
The Bessemer process revolutionized steel production by providing the first inexpensive method for mass production. This innovation dramatically impacted society, especially in building and construction, enabling the creation of towering skyscrapers.
The availability of low-cost steel also led to the replacement of iron in railroad construction and other uses. The ability to produce large quantities of steel facilitated the growth of cities by providing the necessary materials for infrastructure and large buildings.
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Bessemer process, the first method discovered for mass-producing steel. Though named after Sir Henry Bessemer of England, the process evolved from the contributions of many investigators before it could be used on a broad commercial basis. It was apparently conceived independently and almost concurrently by Bessemer and by William Kelly of the United States. As early as 1847, Kelly, a businessman-scientist of Pittsburgh, began experiments aimed at developing a revolutionary means of removing impurities from pig iron by an air blast. Kelly theorized that not only would the air, injected into the molten iron, supply oxygen to react with the impurities, converting them into oxides separable as slag, but that the heat evolved in these reactions would increase the temperature of the mass, keeping it from solidifying during the operation. After several failures, he succeeded in proving his theory and rapidly producing steel ingots.
In 1856 Bessemer, working independently in Sheffield, developed and patented the same process. Whereas Kelly had been unable to perfect the process owing to a lack of financial resources, Bessemer was able to develop it into a commercial success. Another Englishman, Robert Forester Mushet, found that adding an alloy of carbon, manganese, and iron after the air-blowing was complete restored the carbon content of the steel while neutralizing the effect of remaining impurities, notably sulfur. A Swedish ironmaster, Goran Goransson, redesigned the Bessemer furnace, or converter, making it reliable in performance. The end result was a means of mass-producing steel. The resultant volume of low-cost steel in Britain and the United States soon revolutionized building construction and provided steel to replace iron in railroad rails and many other uses.
The Bessemer converter is a cylindrical steel pot approximately 6 metres (20 feet) high, originally lined with a siliceous refractory. Air is blown in through openings (tuyeres) near the bottom, creating oxides of silicon and manganese, which become part of the slag, and of carbon, which are carried out in the stream of air. Within a few minutes an ingot of steel can be produced, ready for the forge or rolling mill.
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The original Bessemer converter was not effective in removing the phosphorus present in sizable amounts in most British and European iron ore. The invention in England, by Sidney Gilchrist Thomas, of what is now called the Thomas-Gilchrist converter, which was lined with a basic material such as burned limestone rather than an (acid) siliceous material, overcame this problem. Another drawback to Bessemer steel, its retention of a small percentage of nitrogen from the air blow, was not corrected until the 1950s. The open-hearth process, which was developed in the 1860s, did not suffer from this difficulty, and it eventually outstripped the Bessemer process to become the dominant steelmaking process until the mid-20th century. The open-hearth process was in turn replaced by the basic oxygen process, which is actually an extension and refinement of the Bessemer process.