Effect of Fluorspar and Industrial Wastes (Red Mud and Ferromanganese Slag) on Desulfurization Efficiency of Molten Steel

Jeong, Tae Su; Park, Joo Hyun

doi:10.1007/s11663-020-01889-7

Cited by 21 publications

(5 citation statements)

References 43 publications

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“…In our previous studies in molten steel, it was confirmed that the sulfur concentration approaches the equilibrium value within 10 to 15 minutes. [36,37] However, in the present study, the sulfur concentration rapidly decreases within 20 to 30 minutes. As shown in Figure 7(a), there is no considerable difference in desulfurization rate according to the change in the TiO 2 content, whereas the desulfurization rate is significantly affected by the C/A ratio as shown in Figure 7(b).…”

Section: B Desulfurization Kinetics Of Incoloy ò 825 Superalloy Via Various Slag Compositionscontrasting

confidence: 60%

“…[16] and [17]. Jeong et al [37] investigated the characteristics of slag by considering the thermochemical and thermophysical properties of slag, i.e., 'log C S 2À À log g' to evaluate the mass transfer coefficient of sulfur in the desulfurization process of molten steel. In the present study, one more thermodynamic parameter, a O (the activity of oxygen in the Incoloy Ò 825 superalloy) is employed, resulting in the 'log C s À log g À log a O ,' because the distribution ratio of sulfur, L s , which is one of the dominant factors affecting the overall mass transfer coefficient from Eq.…”

Section: B Desulfurization Kinetics Of Incoloy ò 825 Superalloy Via Various Slag Compositionsmentioning

confidence: 99%

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Desulfurization Behavior of Incoloy® 825 Superalloy by CaO-Al2O3-MgO-TiO2 Slag

Cho

Martinsson

Sichen

et al. 2021

Metall Mater Trans B

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Ni-based superalloy, which has excellent high-temperature strength and corrosion resistance, is mainly used in aviation materials, high-performance internal combustion engines, and turbines for thermal and nuclear power generation. For this reason, refining the impurities in Ni-based superalloys is a very important technical task. Nevertheless, the original technology for the melting and refining of Ni-based superalloys is still insufficient. Therefore, in this study, the effect of the CaO-Al2O3-MgO-TiO2 slag on the removal efficiency of an impurity element sulfur in Incoloy® 825 superalloy, one of the representative Ni-based superalloys, was investigated. The desulfurization behavior according to the change of TiO2 content and CaO/Al2O3 (=C/A, basicity) ratio as experimental variables was observed at 1773 K (1500 °C). Although the TiO2 content in the slag increases to 15 mass pct, the mass transfer coefficient of sulfur in molten alloy showed a constant value. Alternatively, under the condition of C/A > 1.0 of slag, the mass transfer coefficient of sulfur showed a constant value, whereas under the condition of C/A < 1.0, the mass transfer coefficient of sulfur greatly decreased as CaO decreased. Hence, in the desulfurization of Incoloy® 825 superalloy using the CaO-Al2O3-MgO-TiO2 slag, the TiO2 content in the slag does not have a considerable effect on the desulfurization rate and desulfurization mechanism (metal phase mass transfer controlled regime), but the basicity of the slag has a significant effect on desulfurization mechanism. When the slag basicity decreases below the critical level, i.e., C/A < 1.0, which is corresponding to sulfur distribution ratio, Ls < 200, it was confirmed that the desulfurization mechanism shifts from the metal phase mass transfer-controlled regime to the slag phase mass transfer-controlled regime due to the variation in the physicochemical properties of the slag such as viscosity and sulfide capacity. In addition, the different desulfurization rates between steel and Ni alloy melts were discussed by employing the diffusivity of sulfur in both systems.

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Section: B Desulfurization Kinetics Of Incoloy ò 825 Superalloy Via Various Slag Compositionscontrasting

confidence: 60%

Section: B Desulfurization Kinetics Of Incoloy ò 825 Superalloy Via Various Slag Compositionsmentioning

confidence: 99%

Desulfurization Behavior of Incoloy® 825 Superalloy by CaO-Al2O3-MgO-TiO2 Slag

Cho

Martinsson

Sichen

et al. 2021

Metall Mater Trans B

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“…The use of effective fluxes that promote lime dissolution becomes crucial. CaF 2 is an effective flux to promote the dissolution of lime, but due to its potential hazards to the environment and human health, it has been widely banned [ 7 ]. Currently, the development of fluoride-free efficient fluxes has received much attention.…”

Section: Introductionmentioning

confidence: 99%

Development of Solid Waste-Based Composite Calcium Ferrite Flux and Its Application in Hot Metal Pre-Dephosphorization

Zhao,

Feng,

Zhang

et al. 2024

Materials

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To enhance the slagging efficiency of the lime-based slag system during the pre-treatment stage of hot metal, a composite calcium ferrite flux based on aluminum industry solid waste was developed in this study. The melting characteristics of the flux and its application in the pre-treatment of hot metal were investigated. The results indicated that the main phases of the composite calcium ferrite were CaFe2O4, Ca2Fe2O5, and Ca2(Fe,Al)2O4. It exhibited high oxidation, high alkalinity, and a low melting point, thereby achieving excellent melting performance. Simulations of various dephosphorization fluxes in the pre-treatment of high-phosphorus hot metal, ordinary hot metal, and kilogram-scale dephosphorization experiment processes were conducted. Under the same experimental conditions, the composite calcium ferrite flux was able to achieve a dephosphorization rate of over 90% and a final phosphorus content of less than 0.02 wt% under high carbon content ([%C] = 3.2 wt%). In the application of hot metal pre-dephosphorization, this flux was able to achieve efficient melting and rapid slagging of lime at a lower temperature, and its slagging time was 50% faster than that of calcium ferrite flux. In addition, this flux enhanced the utilization efficiency of lime during the steelmaking process, effectively prevented the agglomeration of slag, and achieved efficient slag–metal separation. These characteristics were significantly better than the application effect of calcium ferrite flux. This flux has significant implications for the industrial application of deep dephosphorization in the pre-treatment stage of hot metal or the early stage of converter steelmaking.

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“…Yang et al [20] utilized red mud in the hot metal pre-treatment dephosphorization process, showing that its addition effectively improved the fluidity of dephosphorization slag and enhanced the rate of pre-dephosphorization. Bang et al [21] and Jeong et al [22] showed that the preparation of desulfurization melts using red mud could achieve or outperform the desulfurization with the use of CaF 2 melts. Our team performed a systematic study on the feasibility of using Bayer red mud as a flux in steelmaking, finding that adding red mud to the CaO-FeO-SiO 2 slag system significantly expanded the liquid phase region between 1300 • C and 1400 • C, extending towards higher CaO content and lower FeO content, indicating the possibility of achieving good fluidity under high alkalinity and low FeO content conditions [23].…”

Section: Introductionmentioning

confidence: 99%

Properties of Fluorine-Free Steelmaking Flux Prepared Using Red Mud

Zhao,

Zhang,

2024

Metals

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The basic oxygen steelmaking process is based on the CaO-FeO-SiO2 ternary slag system, characterized by a high melting point and low lime dissolution rate, often becoming one of the key factors limiting the efficiency of the converter. The bulk solid waste red mud, produced by the Bayer alumina process and rich in Fe2O3/Al2O3/Na2O, significantly reduces the melting point of the steelmaking slag system and enhances the efficiency of lime dissolution. This study utilized red mud as the main raw material to prepare a fluoride-free flux. An in situ online observation system was used to measure the melting point of the flux and the dissolution rate of lime in the flux. The results indicate that the melting point of the red mud-based flux is below 1200 °C, and under the same conditions, the lime dissolution rate is 10 to 15 times higher than when this flux is not used. Experiments in a 10 kg induction furnace show that using this flux, the dephosphorization rate under conditions without oxygen blowing is close to 40%, far higher than the rate achieved using CaF2. Under oxygen-blowing conditions, the dephosphorization rate using the red mud-based flux is comparable to that of CaF2, and significantly higher than without any flux, especially under high [C] content conditions. The data show that the red mud-based flux has the potential to be widely used as a fluoride-free flux in the steelmaking process.

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Effect of Fluorspar and Industrial Wastes (Red Mud and Ferromanganese Slag) on Desulfurization Efficiency of Molten Steel

Cited by 21 publications

References 43 publications

Desulfurization Behavior of Incoloy® 825 Superalloy by CaO-Al2O3-MgO-TiO2 Slag

Desulfurization Behavior of Incoloy® 825 Superalloy by CaO-Al2O3-MgO-TiO2 Slag

Development of Solid Waste-Based Composite Calcium Ferrite Flux and Its Application in Hot Metal Pre-Dephosphorization

Properties of Fluorine-Free Steelmaking Flux Prepared Using Red Mud

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