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Mechanism Study of the Blocking of Ladle Well Due to Sintering of Filler Sand
KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
KTH, School of Industrial Engineering and Management (ITM), Production Engineering.ORCID iD: 0000-0002-6127-5812
KTH, School of Industrial Engineering and Management (ITM), Production Engineering.ORCID iD: 0000-0002-3548-8638
2015 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArticle in journal (Refereed) Published
Abstract [en]

The present work is aimed at a mechanism study of blocking of ladle well by filler sand. Laboratory experiments are carried out using two different chromite-based filler sands. The interaction between the liquid steel and the sand is also studied by using steels containing different contents of Mn and Al. The reaction between the silica phase and the chromite phase is found to be the main mechanism for the sintering of sand. The reaction results in a liquid oxide phase, which becomes the binding phase between the solid oxide grains. The amount of silica phase and its grain size are found to have great impact on the formation of the liquid oxide phase. Faster formation of the liquid oxide phase leads to more serious sintering of the sand. It is found that liquid steel can hardly infiltrate into sand. On the other hand, the presence of steel considerably increases the amount of liquid phase and enhances the sintering of the sand.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2015.
Keyword [en]
Filler sand, Ladle free opening, Liquid steel, Sintering, Chromite, Chromite deposits, Fillers, Ladles, Liquids, Manganese, Sand, Silica, Binding phase, Chromite phase, Laboratory experiments, Liquid oxides, Liquid Phase, Liquid steels, Mechanism studies, Solid oxide
National Category
Materials Engineering
URN: urn:nbn:se:kth:diva-176191DOI: 10.1002/srin.201500118ScopusID: 2-s2.0-84933544611OAI: diva2:873975

QC 20151125

Available from: 2015-11-25 Created: 2015-11-02 Last updated: 2016-08-16Bibliographically approved
In thesis
1. Study on the Interaction between Refractory and Liquid Steel Regarding Steel Cleanliness
Open this publication in new window or tab >>Study on the Interaction between Refractory and Liquid Steel Regarding Steel Cleanliness
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present thesis focuses on the interaction between refractory and liquid steel. The aim of this work is to understand the interaction behavior between refractory and liquid steel regarding steel cleanliness. The effect of different refractories on different inclusions in Al-killed steel was studied in a furnace. The sintering mechanism of filler sand were also investigated in laboratory. In the industrial trials, the attachments of different oxides on the walls of submerged entry nozzle (SEN) were discussed in the cases of high strength low alloy steel (HSLA) and ultra-low carbon steel (ULC).

It is found that the effect of alumina and spinel refractory on all the three types of inclusions is very little, while MgO refractory influences the inclusions depending on the activity of dissolved oxygen in liquid steel. At low oxygen level, alumina inclusions could transform into spinel inclusions with the help of MgO refractory, while the effect on spinel and calcium aluminate inclusions is not evident. On the other hand, when the activity of dissolved oxygen is high enough, the evolution of spinel inclusions from alumina inclusions could not be seen.

The reaction between chromite and silica grains leading to liquid formation is the main mechanism for the sintering of filler sand. The factors viz. steel composition, silica size and content, operation temperature and process holding time have a strong influence on the sintering of the filler sand. Smaller size and higher content of silica in sand, steel grades containing higher Mn and Al contents, higher temperature and longer holding time would result in serious sintering. The choice of the sand needs to take those factors into account.

The results show that solid alumina particles are always agglomerated on the inner wall of SEN in the case of ULC steel. The top slag with high FeO and MnO contents is considered as the main reason of this kind of attachments. The removal of slag might be a good method to avoid the attachments. In the case of HSLA steel, liquid calcium aluminate inclusions could attach on the inner wall of SEN as well. The smoothness of the inner wall of the SEN holds the key of liquid attachments. In addition, the attachment situation on the outer wall of SEN depends on the operations. The oxygen entrainment through the mold powder would result in the formation of plate-like alumina attachments. The control of reoxidation due to oxygen entrainment would help to avoid this situation.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. 48 p.
refractory, inclusions, Al-killed steel, submerged entry nozzle, clogging
National Category
Metallurgy and Metallic Materials
urn:nbn:se:kth:diva-190071 (URN)978-91-7729-006-3 (ISBN)
Public defence
2016-09-15, Sal F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)

QC 20160816

Available from: 2016-08-16 Created: 2016-08-04 Last updated: 2016-08-16Bibliographically approved

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