Chemical Processes and Heat Loss in Cupolas

Landefeld, C. F.

doi:10.1007/978-1-4613-1013-6_5

Cited by 2 publications

(2 citation statements)

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“…The dual stream model 6) was adopted in the calculation, that is the droplet of scrap iron and steel fall through the cupola separately, and they do not mix until the very last stage of the cupola process. As these drops drip downward in the coke bed, they react with coke and the ascend-ing gas.…”

Section: Reactions In Cupola Melting Processmentioning

confidence: 99%

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Numerical Analysis of Reactions in a Cupola Melting Furnace

Sun

Sahajwalla

2004

ISIJ International

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Composition variations of metal and slag in a cupola melting process were investigated by a reaction model for gas/liquid iron/coke and slag/liquid iron systems. A significant amount of alloy elements is lost due to the gas oxidation in furnace shaft. Carbon in metals is determined by gas oxidation and carbon pickup from coke in the shaft. Manganese and silicon are mainly lost by gas oxidation in shaft. Sulfur increases in shaft by pickup from coke but decreases in siphon by slag desulphurisation. There is no significant phosphorus change in shaft, but phosphorus increases in siphon. Oxides formed in shaft contribute 20 % of total tapped slag, in which SiO 2 contribute 40 % of total SiO 2 in the tapped slag.KEY WORDS: scrap melting; kinetics; metallurgical reactions; coke packed bed; mathematical model. ing gas. The reactions of liquid metal drops containing carbon, silicon, manganese, sulfur, phosphorus or other alloying elements, with gas containing nitrogen, oxygen, carbon dioxide, and carbon monoxide take place simultaneously at the gas/metal interface. At the other side of the liquid metal drop, that is the interface between coke and liquid, carbon and sulfur dissolution into liquid metal from coke occur simultaneously. Then, the liquid metal, formed at bottom of shaft from those droplets, moves to the siphon † where it reacts with slag containing lime, silica, alumina, oxides of iron, manganese and phosphorus, or sulfides. The siphon containing liquid metal pool and slag layer at it top; the pressure in siphon, close to the tuyeres' gas pressure, is slightly above the atmosphere. This slag is formed by ash in coke, oxidation products of solid or liquid metal, fluxing materials, and refractory dissolution. Finally, the liquid metal pool is tapped out from the siphon with an appropriate composition for cast iron product-high carbon, silicon and manganese and low sulfur and phosphorus.The reactions of metal and slag are summarized in Table 1. The equilibrium constants [7][8][9][10][11][12] for each individual reaction are given along with the reactions. These reactions occur continuously and most of them simultaneously, thus making the cupola furnace a complex metallurgical reactor. Achieving optimum chemical composition of the metal through control of this series of reactions in the process is the key factor in foundry productivity, environmental performance and quality control. For example, the oxidation of a metal component such as silicon in the shaft will cause silicon loss in the cast iron product, and this lost silicon becomes silica in slag as industrial waste. The silica in slag has a strong tendency to erode the basic refractory lining, and decrease the slag capacities for sulfide and phosphate. The latter may result in the metal sulfur and phosphorus reaching unacceptable levels. To prevent such scenarios, more limestone is required. However, this costs more, increases the slag waste amount, fluxing materials, and therefore, fuel consumption and carbon dioxide emission.The chemical reactions betwe...

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Section: Reactions In Cupola Melting Processmentioning

confidence: 99%

“…For silicon, manganese, phosphorus or iron, their oxidation will occur only when interface oxygen reach the oxygen activity with which they are in equilibrium, ............. (6) where iϭsilicon, manganese or phosphorus.…”

Section: Gas/metal Reactionmentioning

confidence: 99%