Hot Metal Desulfurization by CaO–SiO2–CaF2–Na2O Slag Saturated with MgO

Cho, Moon Kyung; Cheng, Jiang; Park, Joo Hyun; Min, Dong Joon

doi:10.2355/isijinternational.50.215

Cited by 31 publications

(12 citation statements)

References 15 publications

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“…[1][2][3][4][5][6][7] Sulfur is harmful to the mechanical properties of steel products (e.g., strength, ductility and toughness). Therefore, it is necessary to remove sulfur from molten steel to under several ppm in order to improve mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Sulfide Capacity of CaO–SiO2–MnO–Al2O3–MgO Slags at 1873 K

Park

2012

ISIJ Int.

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The sulfide capacities of the CaO-SiO2-MnO-Al2O3-5 mass% MgO slags were measured at 1 873 K over a wide composition range using a gas-slag equilibration method. The effects of basicity and the activity coefficient of sulfide on the sulfide capacity of molten slag were also investigated based on the structural view of silicate melts. In the multicomponent silicate melts containing high MnO (up to about 50 mass%), the sulfide capacity mainly increased with increasing MnO content. The capacity and modified Vee ratio, i.e. (CaO+MnO+MgO)/ (SiO2+Al2O3), showed a good linear relationship. Assuming that the basicity and the stability of sulfide ions in the slag are proportional to the activity of basic oxides and the activity coefficient of sulfides, the composition dependency of the sulfide capacity is well described by changes in the aMO to γMS (M=Ca, Mn) ratio. The substitution of silica by alumina did not affect the sulfide capacity of the slags not only because of an increase in the activity of basic oxides but also because of a decrease in the stability of sulfides as Al2O3/SiO2 ratio increased. In the high silica melts of which silica content greater than about 30 mass%, the sulfide capacity increased with increasing MnO/CaO ratio, whereas it decreased by increasing the MnO/CaO ratio in the low silica melts (< about 30 mass%). This tendency of sulfide capacity resulted in the clock-wisely rotating iso-capacity contours in the CaO-SiO2-MnO-Al2O3-MgO system at 1 873 K. The dissolution mechanism of sulfur in the MnO-containing calcium silicate melts can be explained not only by the difference in the structural role of Ca 2+ and Mn 2+ ions but also by the changes in the content of O 2-ions according to the silica content.KEY WORDS: sulfide capacity; CaO-SiO2-MnO-Al2O3-MgO slag; basicity; sulfide stability; silicate structure; free oxygen.

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Section: Introductionmentioning

confidence: 99%

Sulfide Capacity of CaO–SiO2–MnO–Al2O3–MgO Slags at 1873 K

Park

2012

ISIJ Int.

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“…[1][2][3][4][5] It is well known that the sulfur is harmful to the mechanical properties of steel products such as strength, ductility and toughness, etc. Therefore, it is necessary to remove the sulfur from molten steel under several ppm in order to improve the mechanical properties of steel products.…”

Section: Introductionmentioning

confidence: 99%

Sulfide Capacity of the CaO–SiO2–MnO Slag at 1873 K

2011

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The sulfide capacity of the CaO-SiO2-MnO slag through the entire composition range was measured at 1 873 K using a gas-slag equilibration method and the effect of basicity and the activity coefficient of sulfide on the sulfide capacity of molten slag was investigated. Furthermore, the relationship between the sulfide capacity and the optical basicity of MnO-containing slags was evaluated in view of industrial applications. Sulfide capacity of the slag linearly increased by increasing the content of MnO not only at a given silica content but also at a fixed Vee ratio (=CaO/SiO2). The capacity and the modified Vee ratio (=(CaO+MnO)/SiO2) showed a good linear relationship. Assuming that the basicity and the stability of sulfide ion in the slag are proportional to the activity of MnO (aMnO) and the activity coefficient of MnS (γMnS), respectively, the composition dependency of sulfide capacity was well described by the changes in the ratio of aMnO to γMnS. The iso-sulfide capacity of the CaO-SiO2-MnO slag at 1 873 K was constructed in the present study. The capacity contours seemed to rotate clock-wisely from the CaO-SiO2 binary side to the MnO-corner. The sulfide capacity increased with increasing ratio of MnO to CaO at relatively acidic region in which silica content greater than about 40 mass%, while the substitution of CaO by MnO does not significantly affect the capacity in the low silica region. The sulfide capacity generally increased with increasing content of MnO regardless of changes in the content of other constituents in multicomponent MnO-containing slags. It is necessary to take different values for the theoretical optical basicity of MnO in order to estimate the sulfide capacity of MnO-containing slags depending on the content of silica.

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“…4. Manganese distribution between slag and steel can significantly affect the steel oxidation [14]. This can be shown as a relation between MnO/Mn and sulphur distribution coefficient, presented in the Figure 5 The dependence exists also between MnO and FeO contents in slag [16,17].…”

Section: Results and Their Analysismentioning

confidence: 99%

The Influence of Chemical Composition of Steel on Steel Desulphurization

Buľko¹,

Kijac²,

Borovský³

2011

Archives of Metallurgy and Materials

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The steel desulphurization in ladle furnace depends on temperature, oxygen and sulphur content in the steel, but mainly on chemical composition and physical properties of slag. Necessary requirement for effective desulphurization is also minimum content of easily reducible oxides in the slag. There are many correlations for expression of slag desulphurization capability, where their functional dependency on each other can be found, mainly between sulphur distribution coefficient, optical basicity, basicity, sulphide capacity, desulphurisation potential of slag and also calcium -aluminate ratio of oxides in slag or content of easily reducible oxides in slag. This work presents statistical and graphical correlation between manganese and slag parameters using the set of approximately 768 heats and based on these, the optimal parameters for slag desulphurization capability are expressed especially for steel grades internally marked as OR1, OR3 inŽeleziarne Podbrezová, a.s. Steel grades OR1 and OR3 were chosen because of difference in manganese content with similar chemical composition of other elements. The MnO content in the slag is one of the most important parameters. Despite the higher scatter of obtained values, the distribution coefficient of sulphur (Ls) is one of the wide range of parameters for whom exists very close dependence on MnO content in slag.Keywords: steel desulphurization, ladle furnace, sulphur distribution coefficient, slagOdsiarczanie stali zależy od temperatury, zawartości tlenu i siarki w stali, ale przede wszystkim od składu chemicznego i właściwości fizycznych żużla. Dla skutecznego odsiarczania konieczna jest również minimalna zawartość łatwo redukowalnych tlenków w żużlu. Istnieje wiele zależności do wyrażenia zdolności żużla do odsiarczania, dla których można znaleźć funkcyjną zależność pomiędzy współczynnikiem podziału siarki, optyczną zasadowością, zasadowością, zawartością siarczków, potencjałem odsiarczania żużla, a także stosunkiem tlenków wapnia do glinu w żużlu lub zawartością łatwo redukowalnych tlenków w żużlu. W pracy przedstawiono statystyczną i graficzną korelację pomiędzy zawartością manganu i parametrami żużla uzyskaną z około 768 wytopów, i na ich podstawie optymalne parametry zdolności żużla do odsiarczania przedstawione zostały dla stali wewnętrznie oznaczonych jako OR1, OR3 wŽeleziarne Podbrezová, a.s. Gatunki stali OR1 i OR3 zostały wybrane ze względu na różnice w zawartości manganu przy podobnej zawartości innych składników. Zawartość MnO w żużlu jest jednym z najważniejszych parametrów. Mimo większego rozrzutu uzyskanych wartości, współczynnik podziału siarki (Ls) jest jednym z wielu parametrów, dla których istnieje bardzo ścisła zależność od zawartości MnO w żużlu.

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Hot Metal Desulfurization by CaO–SiO2–CaF2–Na2O Slag Saturated with MgO

Cited by 31 publications

References 15 publications

Sulfide Capacity of CaO–SiO<sub>2</sub>–MnO–Al<sub>2</sub>O<sub>3</sub>–MgO Slags at 1873 K

Sulfide Capacity of CaO–SiO<sub>2</sub>–MnO–Al<sub>2</sub>O<sub>3</sub>–MgO Slags at 1873 K

Sulfide Capacity of the CaO–SiO2–MnO Slag at 1873 K

The Influence of Chemical Composition of Steel on Steel Desulphurization

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Hot Metal Desulfurization by CaO–SiO2–CaF2–Na2O Slag Saturated with MgO

Cited by 31 publications

References 15 publications

Sulfide Capacity of CaO&ndash;SiO<sub>2</sub>&ndash;MnO&ndash;Al<sub>2</sub>O<sub>3</sub>&ndash;MgO Slags at 1873 K

Sulfide Capacity of CaO&ndash;SiO<sub>2</sub>&ndash;MnO&ndash;Al<sub>2</sub>O<sub>3</sub>&ndash;MgO Slags at 1873 K

Sulfide Capacity of the CaO–SiO2–MnO Slag at 1873 K

The Influence of Chemical Composition of Steel on Steel Desulphurization

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Sulfide Capacity of CaO–SiO<sub>2</sub>–MnO–Al<sub>2</sub>O<sub>3</sub>–MgO Slags at 1873 K

Sulfide Capacity of CaO–SiO<sub>2</sub>–MnO–Al<sub>2</sub>O<sub>3</sub>–MgO Slags at 1873 K