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A cupola or cupola furnace is a melting device used in foundries that can be used to melt ... During the melting process a chemical reaction takes place between the ...
The process begins by preparing the puddling furnace. This involves bringing the furnace to a low temperature and then fettling it. Fettling is the process of painting the grate and walls around it with iron oxides, typically hematite ; [ 11 ] this acts as a protective coating keeping the melted metal from burning through the furnace.
The advantage of the induction furnace is a clean, energy-efficient and well-controlled melting process, compared to most other means of metal melting. Most modern foundries use this type of furnace, and many iron foundries are replacing cupola furnaces with induction furnaces to melt cast iron, as the former emit much dust and other pollutants ...
The cupola furnace is ideally suited to this task, but since one reason for the existence of direct reduction processes is the non-use of coke, other melting furnaces have emerged. The COREX process , in operation since 1987, consists of a direct-reduction shaft reactor feeding a blast furnace crucible, in which the pre-reduced ore is brought ...
The Luppen is subsequently remelted in either the blast furnace or the cupola furnace, or the Martin-Siemens furnace, because it involves melting a pre-reduced, iron-rich charge. [22] The process has been effective in treating ores abundant in nickel(II) oxide, vanadium, and other metals. [9]
Melting continued using the cupola. Most requirements on the foundry were for gray iron, the material normally used in machine tool castings. With the discovery of ductile iron, the foundry began producing ductile in the 1950s, using open ladle treatments or the Gazal porous plug process. Not many machine tool parts were needed in ductile iron.
The Bessemer process was the first inexpensive industrial process for the mass production of steel from molten pig iron before the development of the open hearth furnace. The key principle is removal of impurities from the iron by oxidation with air being blown through the molten iron.
Their process was known as the Siemens–Martin process or Martin–Siemens 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 .