The effect of Li2O on the evaporation and structure of low-fluoride slag for vacuum electroslag remelting

Ju, Jiantao; Ji, Guangheng; Tang, Chenmei; Yang, Kang; Zhu, Zhihong

doi:10.1016/j.vacuum.2020.109920

Cited by 7 publications

(3 citation statements)

References 34 publications

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“…The center of gravity of (AlO 6 )-octahedra shifts to a higher wave number, and the transmission peak intensity of (AlO 6 )-octahedra increases relatively. According to previous studies [ 33 ], this is because O 2− provided by K 2 O reacts with (AlO 4 )-tetrahedra to produce (AlO 6 )-octahedra, thus promoting the depolymerization of slag network structure. This is related to the Ti-O stretching vibration at about 420 cm −1 , and varying K 2 O content has a slight effect on the structure.…”

Section: Resultsmentioning

confidence: 97%

Fluoride Evaporation of Low-Fluoride CaF2-CaO-Al2O3-MgO-TiO2-(Na2O-K2O) Slag for Electroslag Remelting

et al. 2023

Materials

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To elucidate the behavior of fluoride evaporation in an electroslag remelting process, the non-isothermal evaporation of the low-fluoride CaF2-CaO-Al2O3-MgO-TiO2-(Na2O-K2O) slag is studied using thermogravimetric analysis. The evaporation law of the melted slag is further verified using thermodynamic calculations. Fourier transformation infrared (FTIR) spectroscopy is used to evaluate the change in slag structure. It is discovered that the principal evaporating substances are CaF2, KF, and NaF, while the evaporation of MgF2, AlF3, and AlOF is less. KF evaporates absolutely in the early stage of the reaction, and CaF2 evaporates in a large proportion during the late reaction period. At 1500 °C, the order of vapor pressure is KF > CaF2. When K2O and Na2O are added to the residue sample at the same time, the evaporation ability of KF is stronger than that of CaF2 and NaF. As the K2O content increases from 0 to 8.3 wt%, evaporation increases from 0.76% to 1.21%. The evaporation rates of samples containing more K2O and those containing more Na2O are 1.48% and 1.32%, respectively. Under the same conditions, K2O has a greater effect on evaporation than Na2O. FTIR results show that the addition of K2O depolymerizes the network structure and that K2O can depolymerize the network structure better than Na2O.

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Section: Resultsmentioning

confidence: 97%

Fluoride Evaporation of Low-Fluoride CaF2-CaO-Al2O3-MgO-TiO2-(Na2O-K2O) Slag for Electroslag Remelting

et al. 2023

Materials

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“…The equilibrium constant can be expressed by Equation (1)-( 4) according to reactions (1)-( 4) [11][12][13].…”

Section: Thermodynamic Analysismentioning

confidence: 99%

Effect of CaF₂ and CaO/Al₂O₃ ratio on evaporation and melting characteristics of low-fluoride CaF₂–CaO–Al₂O₃–MgO–TiO₂ slag for electroslag remelting

Zhang

et al. 2022

Ironmaking & Steelmaking

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The present study focuses on the evaporation of fluoride from low-fluoride CaF 2 -CaO-Al 2 O 3 -MgO-TiO 2 slag with varying CaF 2 content and CaO/Al 2 O 3 mass ratio and the melting characteristics of the slag. Moreover, thermodynamic and kinetic calculations are made to reveal the fluoride evaporation mechanism. The results show that the gaseous substance evaporated from the slag is mainly CaF 2 . The calculated vapour pressure in a sequence is CaF 2 > MgF 2 > AlF 3 > AlOF. Furthermore, with the increase in CaF 2 content from 15 to 30 wt-%, the evaporation of fluoride increases from 0.934 to 1.047%, and the melting temperature drops from 1480 to 1443°C. With the increase in the CaO/ Al 2 O 3 mass ratio from 0.8 to 1.4, the weight loss increases from 0.92 to 1.95% and then decreases to 1.70%, and the melting point drops from 1460 to 1324°C. The slag evaporation is controlled by the Valensi reaction mechanism, and its mechanism function is G(α) = α+(1−α)ln(1−α), which belongs to two-dimensional diffusion.

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“…In terms of Li 2 O-added slag, Kim et al [1] believed that Li 2 O in mold flux could effectively reduce the viscosity of the flux. Besides, the evaporation behaviour of fluoride in Li 2 O-containing ESR slags was studied by Ju et al [27] as well. It was reported that Li 2 O can improve slag properties, but would aggravate the evaporation of fluoride.…”

Section: Introductionmentioning

confidence: 99%

Study on volatilization behaviour of BOF converter slag containing CaCl₂

Yan

Deng

Zhu

2023

Ironmaking & Steelmaking

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The volatilization behaviour of CaCl 2 -containing basic oxygen furnace (BOF) slags was investigated in laboratory at steelmaking temperature. During the melting process, the volatilization ratio was measured, and the volatile compounds were collected with some conductive tapes. Thermogravimetric analysis was conducted to clarify the volatilization of CaCl 2 -containing slags, and the volatilization ratio was also calculated by the thermodynamic software HSC. It was found that volatilization takes place in both CaCl 2 -containing and CaF 2 -containing BOF slags, but their influential mechanisms are different. FeCl 2 is the main volatile compound in CaCl 2 -containing BOF slags. The increasing contents of CaCl 2 and FeO in these slags are favourable for volatilization, while higher slag basicity plays the opposite role. In the case of CaF 2 -containing BOF slags, the volatilization compounds have little relation to the FeO content in the slags, and the volatilization ratio is smaller than that of CaCl 2 -containing BOF slag.

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The effect of Li2O on the evaporation and structure of low-fluoride slag for vacuum electroslag remelting

Cited by 7 publications

References 34 publications

Fluoride Evaporation of Low-Fluoride CaF2-CaO-Al2O3-MgO-TiO2-(Na2O-K2O) Slag for Electroslag Remelting

Fluoride Evaporation of Low-Fluoride CaF2-CaO-Al2O3-MgO-TiO2-(Na2O-K2O) Slag for Electroslag Remelting

Effect of CaF₂ and CaO/Al₂O₃ ratio on evaporation and melting characteristics of low-fluoride CaF₂–CaO–Al₂O₃–MgO–TiO₂ slag for electroslag remelting

Study on volatilization behaviour of BOF converter slag containing CaCl₂

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The effect of Li2O on the evaporation and structure of low-fluoride slag for vacuum electroslag remelting

Cited by 7 publications

References 34 publications

Fluoride Evaporation of Low-Fluoride CaF2-CaO-Al2O3-MgO-TiO2-(Na2O-K2O) Slag for Electroslag Remelting

Fluoride Evaporation of Low-Fluoride CaF2-CaO-Al2O3-MgO-TiO2-(Na2O-K2O) Slag for Electroslag Remelting

Effect of CaF2 and CaO/Al2O3 ratio on evaporation and melting characteristics of low-fluoride CaF2–CaO–Al2O3–MgO–TiO2 slag for electroslag remelting

Study on volatilization behaviour of BOF converter slag containing CaCl2

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Effect of CaF₂ and CaO/Al₂O₃ ratio on evaporation and melting characteristics of low-fluoride CaF₂–CaO–Al₂O₃–MgO–TiO₂ slag for electroslag remelting

Study on volatilization behaviour of BOF converter slag containing CaCl₂