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Sulfide Capacity in Ladle Slag at Steelmaking Temperatures
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.ORCID iD: 0000-0001-5080-8401
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.ORCID iD: 0000-0002-3548-8638
2015 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 46, no 6, 2609-2615 p.Article in journal (Refereed) PublishedText
Abstract [en]

Sulfide capacity measurements were conducted at 1823 K and 1873 K (1550 degrees C and 1600 degrees C) for the quaternary Al2O3-CaO-MgO-SiO2 system, for typical compositions used in the ladle in steelmaking. A copper-slag equilibrium was used under controlled oxygen and sulfur potentials. The sulfide capacity is strongly dependent on the composition and it was found to increase with the basic oxides, while it decreases with increase of the acidic components. It was found that CaO is more effective in holding sulfur in the slag compared to MgO when replacing SiO2. For the present slag compositions, Al2O3 and SiO2 behaved similar with respect to sulfur, and no considerable effect could be recorded when replacing one for the other. The sulfide capacity was also found to be strongly dependent on the temperature, increasing with temperature. The present results were compared with industrial data from the ladle, after vacuum treatment, and they were in good agreement.

Place, publisher, year, edition, pages
Springer, 2015. Vol. 46, no 6, 2609-2615 p.
Keyword [en]
SILICATE MELTS, CAO-AL2O3-SIO2 SLAGS
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-180619DOI: 10.1007/s11663-015-0444-5ISI: 000367067600023ScopusID: 2-s2.0-84946489157OAI: oai:DiVA.org:kth-180619DiVA: diva2:896102
Note

QC 20160120

Available from: 2016-01-20 Created: 2016-01-19 Last updated: 2016-02-29Bibliographically approved
In thesis
1. Sulfur and nitrogen in ladle slag
Open this publication in new window or tab >>Sulfur and nitrogen in ladle slag
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present work deals with some aspects of slags related to secondary metallurgy in the steelmaking process. More specifically the focus is given to sulfur and nitrogen in ladle slags. Even though slags have been fairly well-researched in the past, the available data for these elements in typical ladle slag compositions is rather scarce. In some cases the available data is in discordance. There are also inconsistencies between the literature data and what is commonly observed in the industrial processes.

Sulfide capacities were measured at steelmaking temperatures, 1823–1873 K, in ladle slags. The data was found to be in reasonable agreement with the industrial process norms. The sulfide capacity was found to increase with the basic oxides CaO and MgO; and decrease with the acidic components Al2O3 and SiO2. The sulfide capacity was also found to increase with temperature.

The dependence of sulfide capacity on the oxygen partial pressure, for slags containing multivalent elements, was investigated experimentally at 1873 K with a slag containing vanadium oxide. A strong dependence of oxygen partial pressure was observed. The sulfide capacity increase by more than two orders of magnitude when the oxygen partial pressure was increased from 4.6×10-16 atm to 9.7×10-10 atm.

The nitrogen solubility and the effect of carbon was investigated in typical ladle slags and the CaO–MgO–SiO2 system at 1873 K. Carbon increases the nitrogen solubility substantially. In the absence of carbon, the nitrogen solubility is extremely low. Low concentrations of cyanide was detected in the carbon saturated slag. This was much lower than the total nitrogen content and formation of cyanide cannot explain the large increase.

The possibility of removing sulfur with oxidation from used ladle slag was investigated experimentally at 1373–1673 K. The sulfur removal of mostly solid slag was found to be a slow process, and would not suitable for industrial practice. At 1673 K the slag was mostly liquid and more than 85% of the sulfur was removed after 60 min of oxidation in pure oxygen atmosphere.

 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. vi, 74 p.
National Category
Metallurgy and Metallic Materials
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-182981 (URN)978-91-7595-845-3 (ISBN)
Public defence
2016-04-01, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20160229

Available from: 2016-02-26 Created: 2016-02-24 Last updated: 2016-02-29Bibliographically approved

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