Role of slag in the steel refining process in the ladle

• Autorzy: Wcisło Z. , Michaliszyn A. , Baka A.
• Języki publikacji: EN

Abstrakty

EN

Purpose: The purpose of this research is to analyse the steel refining technology in a ladle furnace including refining slag formation in the ladle. The research was conducted using chromium-nickel- molybdenum steel intended for heat treatment in order to produce crankshafts. Design/methodology/approach: This research was conducted in a ladle furnace with the capacity of 65 Mg of steel. Data from 10 melts were analysed. Samples of refining slag and metal were taken to analyse their chemical composition. On their basis researchers analysed the process of desulphurisation of steel at the ladle furnace workstation. Calculations were made concerning the equilibrium chemical composition of slag to determine the share of gas phase, liquid phase and solid precipitations. The calculations were made using a thermodynamic software FactSage 6.2. Findings: Analysing the process of desulphurisation of steel under slag with the average chemical composition of: CaO - 54.0%, Al₂O₃ - 30.2%, SiO₂ 9.0%, MgO - 8.2%, and FeO content at the level of 0.94% drew attention to a high degree of desulphurisation at the level of 86%. Due to this fact it was possible to obtain high basicity of slag: V=CaO/SiO₂ at the level of 6.21. Mannesmann index, which characterizes the ability of slag to remove sulphur and non-metallic inclusions from steel and is defined as M=(CaO/SiO₂)/Al₂O₃, amounted to 0.21%-1 and was too low in comparison to the required one ranging from 0.35-0.45%-1. The calculations concerning the equilibrium chemical composition of slag, which determined the share of gas phase, liquid phase and solid precipitations, were performed using the thermodynamic software FactSage 6.2. These calculations showed that there were no solid precipitations present. The refining process under slag used in this research proved to be extremely efficient in terms of desulphurisation. Research limitations/implications: It was concluded that the slag forming technology in the ladle is correct in terms of materials used, both as far as their type and amount are concerned. Deoxidation is efficient. Practical implications: It is important to ensure that the furnace slag does not enter the ladle. As a result, it will be possible to improve the quality of the refining slag. Using the thermodynamic software FactSage 6.2 can contribute to modifying the chemical composition of the refining slag and result in an improvement of refinement as well as a better protection of the refractory lining of the ladle. Originality/value: In order to calculate the equilibrium chemical composition of slag researchers used the thermodynamic software FactSage 6.2. Its use in practice can help select slag forming materials that are characterized by high refining parameters.

Słowa kluczowe

EN

ladle furnace; refining slag; steel desulphurisation

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2012
• Tom: Vol. 55, nr 2
• Strony: 390--395
• Opis fizyczny: Bibliogr. 7 poz., rys., tab.

Twórcy

autor

Wcisło Z.

• Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków, Poland

autor

Michaliszyn A.

• Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków, Poland

autor

Baka A.

• Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków, Poland

Bibliografia

• [1] T. Lis, Metallurgy steel with high purity, Silesian University of Technology Publishing House, Gliwice, 2009 (in Polish).
• [2] T. Lis, Desulphurisation of steel by using slag with regulated chemical composition, Metallurgist - News Metallurgical 5 (1994) 146-149 (in Polish).
• [3] M. Dziarmagowski, J. Falkus, M. Karbowniczek, Z. Wcisło, J. Starczewski, Production method of the refining slag used in the manufacture of steel, Patent no. 181057 (in Polish).
• [4] Z. Wcisło, M. Kruciński, M. Dziarmagowski, Steel Refining technology In VAD Process, Proceedings of the XIII Konferencje elektroocelaru a mimopecni zpracovani oceli, Rożnov pod Radhostem, Czechy, 1997, 156-160.
• [5] T. Satek, Z. Buzek, The mutual comparison of operating results for LF and ASEA-SKF, Proceedings of the XIII Konferencje elektroocelaru a mimopecni zpracovani oceli, Rożnov pod Radhostem, Czechy, 1997, 161-166 (in Slovak).
• [6] H. Krztoń, J. Pogorzałek, P. Różański, B. Smolec, Determination of reusability of slag, from afterfurnace treatment of liquid steel. Characteristics of ladle waste slag, Metallurgist - News Metallurgical 6 (2009) 394-399 (in Polish).
• [7] J. Barański, U. Galisz, Ladle Furnace-unit for refining steel, Proceedings of the VI International Conference on Metallurgy, Rudy Raciborskie, 1995 (in Polish).