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Slagline refractory
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
MEFOS, Luleå, Sweden.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
SSAB Tunnplåt AB, Sweden.
2008 (English)In: Proceedings for the SCANMET III-3rd International Conference on Process Development in Iron and Steel making, 2008, 377-384 p.Conference paper (Refereed)
Abstract [en]

An important part to develop in existing ladle metallurgy processes is the ladle as a reaction vessel. The ladle refractory has several vital functions and must withstand chemical, thermal and mechanical wear for longer ladle cycle times to meet higher steelmaking productivity and lower production costs. Extensive refractory wear can be caused by complex united actions such as refractory manufacturing, ladle metallurgy practice, steel and slag composition. A special exposed area is the refractory slagline.

The presented results come from one collaborative project with academic work and industrial trials to identify causes of extensive wear in the slagline. The investigation has been carried out on the slagline MgO-refractories after service. The microscopy characterisation results have then been compared to those from thermodynamic calculations by Thermo-Calc software.

It was found that the refractory microstructure at the hot-face had been totally or partly penetrated and reacted by slag. The observed phases were magnesia-alumina spinel, slag, calcium silicates and dispersed metallic iron rich phases. Closer analyses of the slag phase showed the presence of calcium silicates and calcium aluminates and some few Mg-Al spinel phases. Further away from the hot-face towards the cold-face, the microstructure was composed mainly of magnesia, small calcium silicates phases and a carbon rich phase and therefore less affected.

The project shows that it is possible to combine the characterisation results from the ostmortem studies of the refractories after service with the thermodynamic calculations so that the information about the corrosion behaviour and the microstructure changes of the refractories at refining conditions can be achieved. Further work to test new refractory materials by industrial trials combined with academic work will be performed.


Place, publisher, year, edition, pages
2008. 377-384 p.
Keyword [en]
refractory, ladle lining, microstructure, corrosion, hot-face, slagline
URN: urn:nbn:se:kth:diva-25167OAI: diva2:356257
MEFOS, Luleo, Sweden: 9-11 June
QC 20101012Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2010-10-13Bibliographically approved
In thesis
1. A study of slag corrosion of oxides and oxide-carbon refractories during steel refining
Open this publication in new window or tab >>A study of slag corrosion of oxides and oxide-carbon refractories during steel refining
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The use of ceramic material as refractories in the manufacturing industry is a common practice worldwide. During usage, for example in the production of steel, these materials do experience severe working conditions including high temperatures, low pressures and corrosive environments. This results in lowered service lives and high consumptions of these materials. This, in turn, affects the productivity of the whole steel plant and thereby the cost. In order to investigate how the service life can be improved, studies have been carried out for refractories used in the inner lining of the steel ladles. More specifically, from the slag zone, where the corrosion is most severe. By combining thermodynamic simulations, plant trails and post-mortem studies of the refractories after service, vital information about the behaviour of the slagline refractories during steel refining and the causes of the accelerated wear in this ladle area has been achieved. The results from these studies show that the wear of the slagline refractories of the ladle is initiated at the preheating station, through reduction-oxidation reactions. The degree of the decarburization process is mostly dependent on the preheating fuel or the environment. For refractories without antioxidants, refractory decarburization is slower when coal gas is used in ladle preheating than when a mixture of oil and air is used. In addition, ladle preheating of the refractories without antioxidants leads to direct wear of the slagline refractories. This is due to the total loss of the matrix strength, which results in a sand-like product. Thermal chemical changes that take place in the slagline refractories are due to the MgO-C reaction as well as the formation of liquid phases from impurity oxides. In addition, the decrease in the system pressure during steel refining makes the MgO-C reaction take place at the steel refining temperatures. This reduces the refractory’s resistance to corrosion. This is a serious problem for both the magnesia-carbon and dolomite-carbon refractories. The studies of the reactions between the slagline refractories and the different slag compositions showed that slags rich in iron oxide lead mostly to the oxidation of carbon/graphite in the carbon-containing refractories. This leads to an increased porosity and wettability and therefore an enhanced penetration of slag into the refractory structure. If the slag contains high contents of alumina and or silica (such as the steel refining slag), reactions between the slag components and the dolomite-carbon refractory are promoted. This leads to the formation of low-temperature melting phases such as calcium-aluminates and silicates. The state of these reaction products during steel refining leads to an accelerated wear of the dolomite-carbon refractory. The main products of the reactions between the magnesia-carbon refractory and the steel refining slag are MgAl2O4 spinels, and calcium-aluminates, and silicates. Due to the good refractory properties of MgAl2O4 spinels, the slag corrosion resistance of the magnesiacarbon refractory is promoted.

Place, publisher, year, edition, pages
Stockholm: US-AB, 2010. x, 50 p.
National Category
Materials Engineering
urn:nbn:se:kth:diva-25221 (URN)978-91-7415-743-7 (ISBN)
2010-09-13, MAVE konferensrum, KTH, Brinellvägen 23, Stockholm, 10:00 (English)
QC 20101013Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2010-10-14Bibliographically approved

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