Post-Mortem Investigation of a Steel Ladle Repair Mix Containing Porous Calcium Magnesium Aluminate Aggregates

Chr. Wöhrmeyer1, Y. Zhou2, M. Szepizdyn3, R.-M. Mineau3, J. Gao3

1 Imerys, Paris/France
2 Jinan New E‘mei, Jinan/China
3 Imerys, Paris/France

Revision

Volume 11, Issue 4, Pages 44 - 50

Abstract

Monolithic ladle linings are cost effcient and environmentally friendly because a signifcant part of the used ladle lining can remain inside the ladle for a long time while only the effectively worn out part needs to be replaced by a repair mix. As repair method for ladle walls shotcreting or casting are often chosen for big re-lining jobs. However, dry-gunning remains one of the most fexible and effcient repair method when smaller repairs are required. For all types of repair methods, beside the corrosion resistance of the material itself, also the bonding between the newly installed repair material and the remains of the previ ously used monolithic material is crucial for the total performance of the monolithic lining and its cost effciency. While thick slag layers that stick on the surface must be removed prior to a repair job, it is often diffcult to remove the thin layer of the castable that has been penetrated by slag. It often remains in place and serves as substrate for the repair material. In this paper, a post-mortem investigation is conducted on a newly developed dry-gunning mix that was installed in a steel ladle wall on top of a slag penetrated castable. The repair mix contains a newly designed porous aggregate as partly replacement for the dense alumina aggregate. This porous aggregate consists of magnesium aluminate and calcium aluminate mi crocrystals. The post-mortem study is investigating both, the corrosion of the dry-gunning mix in direct contact with steel and slag on the hot side as well as the microstructural changes at its interface to the slag penetrated castable that served as substrate for the repair mix.

Keywords

re-lining, repair mix, porous synthetic aggregate

References

[1] Ito, S.; Inuzuka, T.: Technical development of refractories for steelmaking. Nippon Steel Technical Report No. 98, July 2008 [2] Braulio, M.; et al.: Spinel-containing aluminabased refractory castables. Ceramics Int. 37 (2011) 1705–1724, 2011 [3] Ogata, M.: Development trend of refractories in Japan. ALAFAR congress, Medellin, Colombia, 2018 [4] Russo, A.A.; et al.: Mechanism for carbon transfer from magnesia-graphite ladle refractories to ultralow-carbon steel. Iron & Steel Technology, Oct. 2016 [5] Kanatani, T.; Imaiida, Y.: Application of an alumina-spinel castable to the teeming ladle for stainless steelmaking. UNITECR’93, 1255–1266 [6] Wöhrmeyer, C.; et al.: Calcium magnesium aluminate aggregates for castables. Int. Colloquium on Refractories, Aachen, Germany, 2017 [7] Tang, H.; et al.: Effects of CMA aggregates on properties of corundum-spinel castables. Conf. on Refractories International, Hangzhou, China, 2018 *Original paper has been published in the conference proceedings of the Int. Colloquium on Refractories (ICR), Aachen, Germany, 2019: Wöhrmeyer, Chr.: How to improve the bonding between used steel ladle castable substrate and dry-gunning repair mix

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