Stabilization and Crystal Characterization of Electric Arc Furnace Oxidizing Slag Modified with Ladle Furnace Slag and Alumina
Abstract
1. Introduction
2. Materials and Methods
2.1. Slag Sampling and Characterization
2.2. Dephosphorization of Steels
2.3. XRD and SEM Analysis
2.4. Image-Pro-Plus Processing and Analysis
2.5. f-CaO Content Determination
2.6. Laboratory-Scale Volume Expansion Testing
3. Results and Discussion
3.1. Dephosphorization of Modified Oxidizing Slag
3.2. XRD Analysis
3.3. SEM Analysis
3.4. Image-Pro-Plus Analysis
3.5. Comparison of Expansion and f-CaO Results
4. Conclusions
- (1)
- The dephosphorization rate of different LFSs using supplement A (LF/CaO = 1/1, Al2O3 content = 15–25%) was more than 45% between 1520 °C and 1600 °C. The phosphorus content of steel is less than 0.03% to meet the set standards of general engineering steel.
- (2)
- XRD results showed that different LFSs had C2S, C3S, CaO, and MgO as the major phases. The characteristics of LFS were altered after high-temperature slag modification, and the primary crystalline phases were FeO and gehlenite (Ca2Al2SiO7).
- (3)
- SEM analysis confirmed that phosphorus was concentrated in the C2S phase during dephosphorization. As the Al2O3 content exceeds 15%, about 2–8% of Al atoms replaced Si atoms, and the C2S phase fraction decreased from 31.4% to 17.1%.
- (4)
- The f-CaO content of the modified oxidizing slag was less than 0.41% (while those of LFS and EAFS were 0.9–3.4% and 1.2–1.4%, respectively). The modified oxidizing slag showed almost no expansion and conformed to the ASTM D2940 standards.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Specimen | Types | Chemical Composition (wt.%) | ||||||
---|---|---|---|---|---|---|---|---|
CaO | SiO2 | Al2O3 | MgO | T-Fe | MnO | S | ||
LFS 1 | (1) | 45.9 | 21.6 | 4.2 | 8.6 | 1.8 | 0.3 | 0.867 |
LFS 2 | (2) | 50.2 | 11.7 | 19.9 | 4.9 | 2.1 | 0.3 | 0.727 |
LFS 3 | (3) | 44.1 | 17.5 | 3.4 | 17.9 | 2.3 | 0.6 | 0.567 |
LFS 4 | (1) | 55.4 | 27.2 | 2.7 | 5.8 | 1.5 | 0.4 | 0.547 |
LFS 5 | (1) | 52.1 | 19.3 | 14.8 | 4.9 | 0.7 | 0.1 | 0.994 |
LFS 6 | (2) | 52.3 | 5.1 | 28.9 | 5.4 | 0.5 | 0.1 | 0.911 |
LFS 7 | (1) | 46.4 | 21.1 | 3.9 | 7.0 | 1.6 | 0.5 | 0.772 |
LFS 8 | (1) | 52.6 | 23.6 | 4.2 | 8.8 | 0.3 | 0.2 | 0.828 |
LFS 9 | (3) | 40.3 | 15.9 | 4.8 | 13.1 | 4.5 | 0.6 | 0.542 |
LFS 10 | (1) | 47.7 | 21.8 | 4.3 | 10.4 | 2.2 | 0.7 | 0.690 |
EAFS 1 | 37.8 | 11.2 | 7.4 | 6.2 | 25.9 | 3.4 | 0.102 | |
EAFS 2 | 28.8 | 11.9 | 6.4 | 3.7 | 28.6 | 4.9 | 0.241 | |
EAFS 3 | 35.6 | 10.7 | 4.5 | 6.9 | 28.4 | 4.5 | 0.097 |
Supplements | LFS (g) | CaO (g) | Al2O3 (%) |
---|---|---|---|
A (for 200 g metal) | 3 | 3 | 15–25 |
A | 525 | 525 | 15–25 |
B | 1050 | 0 | 15–25 |
C | 0 | 1050 | 15–25 |
Sample | Chemical Composition (wt.%) | Initial [P] | Final [P] | De-P 1 | ||||
---|---|---|---|---|---|---|---|---|
CaO | SiO2 | Al2O3 | FexO | P2O5 | (%) | |||
S1 (A) | 24.4 | 8.4 | 21.7 | 41.3 | 0.551 | 0.0477 | 0.0197 | 58.7 |
S2 (A) | 25.8 | 7.9 | 20.1 | 40.2 | 0.455 | 0.0451 | 0.0211 | 53.2 |
S3 (A) | 24.5 | 8.6 | 17.6 | 44.5 | 0.546 | 0.0432 | 0.0191 | 55.8 |
S4 (A) | 27.2 | 7.3 | 22.3 | 27.2 | 0.643 | 0.0389 | 0.0156 | 59.9 |
S5 (A) | 22.3 | 8.1 | 20.4 | 33.6 | 0.757 | 0.0496 | 0.0152 | 69.4 |
S4 (B) | 23.4 | 9.9 | 15.3 | 35.6 | 0.445 | 0.0403 | 0.0221 | 45.2 |
S5 (B) | 16.6 | 13.9 | 20.3 | 33.8 | 0.375 | 0.0314 | 0.0192 | 38.9 |
S6 (B) | 20.8 | 8.8 | 24.8 | 25.9 | 0.397 | 0.0495 | 0.0324 | 34.5 |
S-(C) | 32.1 | 4.3 | 28.7 | 26.2 | 0.844 | 0.0514 | 0.0081 | 84.2 |
Sample | Phase | Chemical Composition, at.% | ||||||
---|---|---|---|---|---|---|---|---|
Ca | Si | Al | Fe | Mg | P | O | ||
S1 | I-FeO | 1.9 | 0.0 | 0.6 | 41.1 | 6.6 | 0.00 | 49.8 |
II-matrix | 14.8 | 5.8 | 14.0 | 7.1 | 0.8 | 0.00 | 57.4 | |
III-C2S | 25.7 | 10.4 | 2.6 | 1.1 | 0.3 | 0.32 | 59.5 | |
S2 | I-FeO | 2.5 | 0.2 | 0.9 | 40.1 | 7.6 | 0.00 | 48.7 |
II-matrix | 14.5 | 5.3 | 14.5 | 8.7 | 1.2 | 0.00 | 55.9 | |
S3 | I-FeO | 0.9 | 0.0 | 0.4 | 36.7 | 13.1 | 0.00 | 48.9 |
II-matrix | 15.1 | 6.1 | 13.2 | 5.8 | 1.0 | 0.00 | 58.9 | |
III-C2S | 28.6 | 8.2 | 7.3 | 1.1 | 0.4 | 0.28 | 54.1 | |
EAFS | I-FeO | 1.1 | 0.2 | 0.7 | 35.8 | 8.3 | 0.00 | 53.9 |
II-matrix | 13.3 | 4.6 | 14.8 | 4.5 | 0.1 | 0.00 | 61.9 | |
III-C2S | 33.1 | 17.5 | 0.4 | 1.0 | 0.1 | 0.47 | 47.4 |
Sample | S1A | S2A | S3A | S4A | S5A | S4B | S5B | S6B | S-C | EAF1 | EAF2 |
---|---|---|---|---|---|---|---|---|---|---|---|
f-CaO (%) | 0.31 | 0.31 | 0.26 | 0.41 | 0.37 | 0.18 | 0.13 | 0.21 | 0.7 | 1.2 | 1.4 |
Expansion (%) | 0.027 | NA 1 | NA 1 | 0.037 | NA 1 | 0.023 | 0.029 | NA 1 | 0.11 | 0.17 | 0.15 |
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Li, C.-C.; Lin, C.-M.; Chang, Y.-E.; Chang, W.-T.; Wu, W. Stabilization and Crystal Characterization of Electric Arc Furnace Oxidizing Slag Modified with Ladle Furnace Slag and Alumina. Metals 2020, 10, 501. https://doi.org/10.3390/met10040501
Li C-C, Lin C-M, Chang Y-E, Chang W-T, Wu W. Stabilization and Crystal Characterization of Electric Arc Furnace Oxidizing Slag Modified with Ladle Furnace Slag and Alumina. Metals. 2020; 10(4):501. https://doi.org/10.3390/met10040501
Chicago/Turabian StyleLi, Chia-Chun, Chi-Ming Lin, Yu-En Chang, Wei-Ti Chang, and Weite Wu. 2020. "Stabilization and Crystal Characterization of Electric Arc Furnace Oxidizing Slag Modified with Ladle Furnace Slag and Alumina" Metals 10, no. 4: 501. https://doi.org/10.3390/met10040501
APA StyleLi, C.-C., Lin, C.-M., Chang, Y.-E., Chang, W.-T., & Wu, W. (2020). Stabilization and Crystal Characterization of Electric Arc Furnace Oxidizing Slag Modified with Ladle Furnace Slag and Alumina. Metals, 10(4), 501. https://doi.org/10.3390/met10040501