USING OF CALCIUM MAGNESIUM ALUMINATE FLUX WITH HIGH MGO CONTENT TO IMPROVE SECONDARY STEEL LADLE LIFE TIME
Evangelista, Paulo César; Jolly, Remy; Wohrmeyer, Christoph; Bruggmann, Christian
http://dx.doi.org/10.4322/tmm.2011.045
Tecnol. Metal. Mater. Min., vol.8, n4, p.285-290, 2011
Abstract
One of the most corroded zones in the secondary steel ladle is the contact area between the metallurgical slag and the refractory lining. The slag zone, even with specially designed Magnesia-Carbon and Doloma-Carbon bricks, is in many cases the life time limiting factor for the whole steel ladle. This makes repairs by gunning or intermediate slag zone replacements necessary. During the slag zone replacement the ladle has to be cooled down with further negative effect on the other parts of the ladle due to thermally induced stresses and consequently crack formation. In order to improve the life time of the slag zone, the impact of OPTIMETTM RG (FLUX B) and OPTIMETTM HM (FLUX C), novel synthetic Calcium Magnesium Aluminate Fluxes (CMA) with high MgO-content, has been studied. Thermodynamic simulations with the FactSage© software and laboratory experiments have been conducted. A traditional slag fluxing practice with fluorspar (CaF2) has been compared with Calcium Aluminate (CA), LDSF® RG (FLUX A), and with these novel synthetic fluxes with different MgO-contents. Calcium Magnesium Aluminate Fluxes (CMA) allow a quick formation of a homogeneous and liquid slag with a high capacity to absorb sulphur and oxide inclusions from the steel bath, very similar to Calcium Aluminate (CA). Calcium Magnesium Aluminate Fluxes (CMA) bring the MgO-content in the slag, right after tapping, close to the saturation concentration and minimise the dissolution of Magnesia-Carbon or Doloma-Carbon bricks in the slag. Life time increase of the slag zone can be expected. Calcium Magnesium Aluminate Fluxes (CMA) help to reduce the specific ladle costs per tonne of steel. The efficiency of high quality steel production can be increased which supports the efforts to reduce the CO2-emissions per ton of produced steel.
Keywords
Synthetic slag, Calcium aluminates, Refractory wear, Secondary steel ladle
Referências
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2 JANSSON, S.; BRABIE, V.; BOHLIN, L. Corrosion mechanism and kinetic behaviour of refractory materials in contact with CaO-Al2O3-MgO-SiO2 slags. In: INTERNATIONAL CONFERENCE ON MOLTEN SLAGS FLUXES AND SALTS, 7., 2004, Cape Town, South Africa. Proceedings... Marshalltown: The South African Institute of Mining and Metallurgy, 2004. p. 341-7.
3 AKKURT, S.; LEIGH, H. D. Corrosion of MgO-C ladle refractories. American Ceramic Society. Bulletin, v. 82, n. 5, p. 32-40, 2003.
4 POIRIER, J. et al. An overview of refractory corrosion: observations, mechanisms and thermodynamic modeling. Refractories Applications Transactions, v. 3, n. 2, p. 2-12, 2007.
5 BLUMENFELD, P.; PERUZZI, S.; PUILLET, M. Recent improvements in Arcelor steel ladles through optimization of refractory materials, steel shell and service conditions. La Revue de Métallurgie-CIT, v. 102, n. 3, p. 233-9, Mar. 2005.
6 REISINGER, P. et al. MgO-Löslichkeit in Stahlwerksschlacken. Berg-und Hüttenmännische Monatshefte, v. 144, n. 5, p. 196-203, 1999.
7 HARATIAN, M.; MARANDIAN, M.; ABOUMAHBOUB. A. The effect of synthetic slag usage on ladle refractory life. In: INTERNATIONAL COLLOQUIUM ON REFRACTOREIS, 47., 2004, Aachen. Proceedings... Warrendale, PA: Association for Iron & Steel Technology, 2004. p. 144-7.
8 OLVIRA, F. C. et al. The use of prefused slags in the manufacture of ultra-clean steel in TAMSA. In: SIMPOSIO NACIONAL DE SIDERURGIA, 18., Mexico, 1996.
9 LACHMUND, H. et al. Cost effectiveness of DH slag treatment with optimized metallurgical results. La Revue de Metallurgie – ATS – JSI, v. 104, n. 10, p. 164-5, Oct. 2007.
10 THERMFACT AND GTT-TECHNOLOGIES. FactSage©. Available from:
11 WÖHRMEYER, C.; JOLLY, R.; BRÜGGMANN, C. Novel fluxing agent for slags in secondary steel ladles to improve refractory life time and steel quality. In: CZECH METALLURGICAL CONFERENCE, 26, 2010, Roznov pod Radhostem. Czech RepublicTechnical University Ostrava, 2010. p. 72-6.
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