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Limestone Dissolution in Converter Slag at 1873 K (1600 degrees C)
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.ORCID iD: 0000-0002-3548-8638
2013 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 44, no 1, 98-105 p.Article in journal (Refereed) Published
Abstract [en]

Decomposition and dissolution of limestone in slag at 1873 K (1600 A degrees C) were studied. The limestone samples were in the shape of cubes (11 mm x 11 mm x 11 mm approximately). The decomposition was carried out both in argon and in slag under argon atmosphere. In order to gain an insight into the phenomenon of slow decomposition, the decomposition process of CaCO3 was simulated using Comsol. The results showed evidently that the decomposition of calcium carbonate was controlled mostly by heat transfer. It was also found that the decomposition product CaO had very dense structure, whether the sample was decomposed in slag or in argon. The slow decomposition and the dense CaO layer would greatly hinder the dissolution of lime in the slag. The present results clearly indicate that the addition of limestone instead of lime would not be beneficial in the converter process.

Place, publisher, year, edition, pages
2013. Vol. 44, no 1, 98-105 p.
Keyword [en]
Calcium-Carbonate, Thermal-Decomposition, Lime, Heat, Dissociation, Mechanism, Pressure, Kinetics
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-101412DOI: 10.1007/s11663-012-9761-0ISI: 000314909000013Scopus ID: 2-s2.0-84874001227OAI: oai:DiVA.org:kth-101412DiVA: diva2:547541
Note

QC 20130320. Updated from submitted to published. Previous title: Limestone dissolution in converter slag at 1873K

Available from: 2012-08-29 Created: 2012-08-28 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Study on the dissolution of lime and dolomite in converter slag
Open this publication in new window or tab >>Study on the dissolution of lime and dolomite in converter slag
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the present study, the dissolution mechanism and rate of lime, limestone and dolomite in converter slag was studied. Lime dissolution in stagnant slag was studied first and dissolution of lime, limestone and dolomite under forced convection were carried out by new experimental setup.

Dissolution of different CaO samples into stagnant converter slags was carried out in a closed tube furnace at 1873K. In the case of CaO-‘FeO’-SiO2 slag, the dissolution of CaO rod in the stagnant slag was retarded after the initial period (2 minutes). A dense layer of 2CaO∙SiO2 was found to be responsible for the total stop of the dissolution. It could be concluded that constant removal of the 2CaO∙SiO2 layer would be of essence to obtain high dissolution rate of lime. In this connection, it was found necessary to study the dissolution of lime in moving slag.

In order to obtain reliable information of lime dissolution under forced convection, the commonly used rotating rod method was examined. Both CFD calculation and cold model experiments showed evidently that the mass transfer due to radial velocity introduced by forced convection was zero if the rod was centrally placed in a cylindrical container. A new experimental design was therefore developed. A cube was placed in the crucible and stirred by Mo rod along with slag. The whole system could be quenched in order to maintain the state of the system at high temperature. A linear relationship between normalized length and time was obtained for lime dissolution. Different lime samples showed big difference in dissolution rate. It was found that the main mechanism of CaO dissolution in slag was due to the removal of 2CaO∙SiO2 layer.

Decomposition and dissolution of limestone and dolomite in slag at 1873 K were studied. The decomposition was carried out both in argon and in slag under argon atmosphere. The decomposition process was simulated using Comsol. The results showed evidently that the decomposition of limestone and dolomite was controlled mostly by heat transfer.

It was also found that the decomposition of limestone product: CaO had very dense structure, no matter the sample was decomposed in slag or in argon. The slow decomposition and the dense CaO layer would greatly hinder the dissolution of lime in the slag. The present results clearly indicate that addition of limestone instead of lime would not be beneficial in converter process.

Discontinuous 2CaO∙SiO2 layer along with MgO∙Fe2O3 particles was found on the surface of the dolomite sample. Some 2CaO∙SiO2 islands were found in the vicinity of the sample in the slag, which revealed therefore that the dissolution was dominated by the peeling-off of the layer of 2CaO∙SiO2-MgO∙Fe2O3 mixture. 2CaO∙SiO2, (Mg, Fe)Oss along with super cooled liquid phases were found inside dolomite sample close to the surface. 2CaO∙SiO2 phase was replaced gradually by 3CaO∙SiO2 towards the centre of the decomposed sample.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. 45 p.
Keyword
dissolution, lime, limestone, dolomite, converter slag
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-101461 (URN)978-91-7501-454-8 (ISBN)
Public defence
2012-09-28, B1, Brinellvägen 23, Kungliga Tekniska Högskolan, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20120829

Available from: 2012-08-29 Created: 2012-08-29 Last updated: 2013-03-20Bibliographically approved

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