Mechanism of Mechanical Activation-Assisted Selective Decalcification of Vanadium-Bearing Steel Slag
- 1College of Metallurgy and Energy, North China University of Science and Technology, Tangshan 063210, China
- 2Yanzhao Iron and Steel Laboratory, North China University of Science and Technology, 21 Bohai Street, Tangshan 063210, China
Abstract
Selective decalcification of vanadium-bearing steel slag via hydrochloric acid pretreatment was investigated in this work. The influences of hydrochloric acid concentration, temperature, reaction time, and liquid-to-solid ratio on Ca and V leaching from mechanically activated and non-activated slag are evaluated. The results show that mechanical activation significantly enhances decalcification selectivity. At an HCl concentration of 1.5 mol·L−1, 40 °C, 8 min, and a liquid-to-solid ratio of 7 mL·g−1, the Ca extraction reached 77.10%, while the V loss rate remains at only 6.08%, resulting in a separation index (SI) of 12.7, significantly higher than that of the non-activated slag (SI = 3.9). XRD and SEM-EDS analyses show the disappearance of Ca2SiO4, CaO, and Fe3O4 after decalcification, accompanied by the formation of a loose and porous surface structure. Ca2SiO4 preferentially dissolves due to its porous structure, whereas Ca2Fe2O5 remains because of its dense layered structure. Furthermore, the lower bond energy of Ca-O than V-O facilitates selective decalcification. ICP analysis shows that the CaO content decreases from 40.83% to 19.87%, while the V2O5 content increases from 2.19% to 2.49%, resulting in vanadium enrichment. Kinetic analysis suggests a shrinking-core model for the decalcification process, with the reaction being predominantly governed by surface chemical control. The apparent reaction order and activation energy are 0.73 and 20.28 kJ·mol−1 respectively. These findings provide theoretical support for selective calcium removal and vanadium enrichment from vanadium-bearing steel slag.
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BibTeX
@article{zhang2026mechanism,
title = {{Mechanism of Mechanical Activation-Assisted Selective Decalcification of Vanadium-Bearing Steel Slag}},
author = {Minhao Zhang and Zekun Wang and Xuan Liu and Ang Zhao and Le Wang and Jinglong Liang},
journal = {Molecules},
year = {2026},
month = oct,
doi = {10.3390/molecules31203596},
url = {https://www.mdpi.com/1420-3049/31/20/3596},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Mechanism of Mechanical Activation-Assisted Selective Decalcification of Vanadium-Bearing Steel Slag
AU - Minhao Zhang
AU - Zekun Wang
AU - Xuan Liu
AU - Ang Zhao
AU - Le Wang
AU - Jinglong Liang
PY - 2026
DA - 2026/10/01
JO - Molecules
DO - 10.3390/molecules31203596
UR - https://www.mdpi.com/1420-3049/31/20/3596
AB - Selective decalcification of vanadium-bearing steel slag via hydrochloric acid pretreatment was investigated in this work. The influences of hydrochloric acid concentration, temperature, reaction time, and liquid-to-solid ratio on Ca and V leaching from mechanically activated and non-activated slag are evaluated. The results show that mechanical activation significantly enhances decalcification selectivity. At an HCl concentration of 1.5 mol·L−1, 40 °C, 8 min, and a liquid-to-solid ratio of 7 mL·g−1, the Ca extraction reached 77.10%, while the V loss rate remains at only 6.08%, resulting in a separation index (SI) of 12.7, significantly higher than that of the non-activated slag (SI = 3.9). XRD and SEM-EDS analyses show the disappearance of Ca2SiO4, CaO, and Fe3O4 after decalcification, accompanied by the formation of a loose and porous surface structure. Ca2SiO4 preferentially dissolves due to its porous structure, whereas Ca2Fe2O5 remains because of its dense layered structure. Furthermore, the lower bond energy of Ca-O than V-O facilitates selective decalcification. ICP analysis shows that the CaO content decreases from 40.83% to 19.87%, while the V2O5 content increases from 2.19% to 2.49%, resulting in vanadium enrichment. Kinetic analysis suggests a shrinking-core model for the decalcification process, with the reaction being predominantly governed by surface chemical control. The apparent reaction order and activation energy are 0.73 and 20.28 kJ·mol−1 respectively. These findings provide theoretical support for selective calcium removal and vanadium enrichment from vanadium-bearing steel slag.
SN - 1420-3049
ER -