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Studies of inclusion behaviour at the metal/slag interface is of great importance for the steel industry in order to achieve better control of both the size and amount of the inclusions, as well as improving the steel quality and the casting process. In this work agglomeration of liquid Al2O3–CaO particles at both steel/argon gas and steel/slag interfaces was studied with a confocal scanning laser microscope. In addition, agglomeration of liquid Al2O3–CaO–SiO2 inclusions present in the slag was investigated. The results showed that liquid inclusions more easily agglomerated to semiliquid inclusions than to liquid inclusions. Moreover, the agglomeration of liquid particles was found to be improved remarkably when the particles were present in the slag compared to when they were in the steel/slag interface. [ABSTRACT FROM AUTHOR]

It is imperative to reduce the pollution and energy consumption in the blast furnace ironmaking process. High pellets operation is a developing direction in the future. The function of blast furnace slag system cannot be ignored. In order to balance the MgO content in blast furnace slag and improve the metallurgical properties of pellets in the high pellets ratio operation, the research on MgO-bearing pellets is necessary. In this paper, the metallurgical properties of MgO-bearing pellets and the properties of blast furnace slag effect by MgO in different raw material conditions, especially for Vanadium Titanomagnetite, were analysed and summarized. This review provided a reference for the development of MgO-bearing pellets and the performance of blast furnace slag effect by MgO. It is hoped to reduce pollution and promote the technical progress of blast furnace ironmaking. [ABSTRACT FROM AUTHOR]

The objective of this article was to study the impact of duration of vacuum degassing process on the type and morphology of non-metallic inclusions which are undesired & unavoidable by product of steelmaking process. During the vacuum degassing stage five top slag and steel samples were taken. All sample occasions measured chemical composition of the molten steel and top slag, and SEM analysis of the non-metallic inclusions. It was seen that during vacuum degassing process the chemistry, dispersions as well as the morphology of the non-metallic inclusions is constantly changing. The Alumina content of the top slag is increased while CaO content is reduced. The percentage share of calcium aluminate type of inclusions verses spinel is increased. In the beginning of the vacuum degassing wt-% of Al in non-metallic inclusions is the highest however as the time passes this wt-% is reduced at the same time inclusions with larger ECDs appear. [ABSTRACT FROM AUTHOR]

The aim of the present work is to adapt tests that are typically used for blast furnace cokes, such as coke reactivity index (CRI) and coke strength after reaction, to ferroalloy production in electric furnaces by developing easier equipment that meets with ISO 18894 standards. Moreover, a new technique has also been developed using thermal gravimetric analysis in order to quickly, inexpensively and reliably find the CRI parameter. As result of this work, a polynomial relationship between coke's reactivity and mass loss slopes of the record line obtained in the gravimetric thermal analysis tests was found. [ABSTRACT FROM AUTHOR]

Iron ore pellets are a prepared burden material for ironmaking that are commonly sintered in a grate kiln furnace system. Deposited material can adhere in chunks to localised regions of the lining of such furnaces, causing lining depletion. Such deposits consist mainly of iron oxides, but alkali, alkaline earth and other oxides formed from disintegrated pellets and fly ash may also be present. In order to investigate methods of preventing such formations, tests have been performed using several different castables and coatings. Samples of liner castables with and without coatings, installed in an industrial furnace, were collected after 6 and 24 months in production use, and characterised using scanning electron microscopy to identify the materials, characterise morphological changes at the deposit-coating-lining interface, and to determine the active chemical reactions. An Al2O3 based coating applied to one of the fields was found to be in good condition after 6 months in use, but no traces of the coating were observed after 24 months in use. A carbon phosphate based coating was not intact after 6 months in use; it was probably burned-up as a result of the oxidising atmosphere. Hematite grains from the deposit material remained at the original deposit-lining interface, while calcium migrated further into the lining. [ABSTRACT FROM AUTHOR]

The objective of this research was to study non-metallic inclusions during vacuum degassing in an ASEA-SKF ladle furnace. Five steel and top slag samples were taken before, during and after vacuum degassing for chemical analysis and scanning electron microscopy. It was concluded that the average CaO/Al2O3 ratios in the top slags became close to the phase C3A. The average CaO/Al2O3 ratios in the inclusions of this study were close to the phase CA6, but at the end of degassing, the average CaO/Al2O3 ratios in the calcium aluminates by subtracting the Al amounts of the inclusions that were assumed to form spinel phases with the available Mg amounts in the inclusions were situated between the phases C12A7 and C3A. By decreasing the S and Al contents of molten steel and at [S]3.[Al]2 less than around 10-7 , the ratio of calcium aluminates to spinels increased continously. It was finally concluded that by increasing the Ca amount in inclusions, their equivalent circle diameters grew, and their aspect ratios went toward unity, and when the amount of Ca measured in the inclusions was more than ∼25 wt-%, inclusions with bigger equivalent circle diameters appeared. [ABSTRACT FROM AUTHOR]

Iron losses during calcium carbide based hot metal desulphurisation have been studied via large scale investigations of slag from the slag pit as well as slag sampling during desulphurisation at SSAB EMEA in Luleå. The desulphurisation slag, after injection of calcium carbide, is normally solid and contains large amounts of iron. An alkali containing mineral, nepheline syenite, was mixed together with the calcium carbide to form a more fluid slag as the iron losses originate from enclosed metal droplets in the slag as well as drawn off hot metal during slag skimming. The slag amount after slag skimming decreased from 28·1 to 25·1 kg t-1 hot metal with addition of 5 wt-% nepheline syenite to the calcium carbide, and the magnetic fraction of the slag from the slag pit decreased from 2·5 to 1·9%. Finally, no negative effect on the reagent efficiency was observed during the trials with addition of nepheline syenite. [ABSTRACT FROM AUTHOR]

This article sets out to study the development of oxide inclusions during the vacuum degassing process at the ASEA-SKF ladle furnace. During the degassing process, five steel and top slag samples were taken, and their chemical compositions were analysed. All steel samples were further analysed by scanning electron microscopy. It was concluded that the vacuum degassing process was a dynamic process during which spinel and calcium aluminate inclusions were dominant. In addition, it was seen that during this process, the percentage share of calcium aluminates compared with spinels, the Ca weight per cent content of the oxides, the average equivalent circle diameter (ECD) of the oxides and the percentage share of the oxides with bigger ECD were increasing, and the oxides tended to form more round shapes. [ABSTRACT FROM AUTHOR]