The Mechanism of Calcium Leaching from Steel Slag Based on the “Water-Acetic Acid” Two-Step Leaching Route

作者：Kai Zhang, Qiong Cang, Lijie Peng, Yitong Wang, Yitong Wang, Shan Zhang, Hongyang Li, Baojia Hu, Baojia Hu, Xin Yao, Du Peipei, Yajun Wang, Yajun Wang · 发表于：Processes · 年份：2025 · DOI：10.3390/pr13124077 · 被引用次数：3 · 研究领域：Metallurgical Processes and Thermodynamics、Chemical Looping and Thermochemical Processes、CO2 Sequestration and Geologic Interactions

Converter steel slag (BOFS) contains abundant reactive Ca-bearing minerals and represents a promising feedstock for indirect CO2 mineralization. However, conventional acid leaching suffers from excessive reagent consumption and low process sustainability. This study develops a “water–acetic acid” two-step leaching strategy aimed at reducing acid/alkali usage while enhancing calcium recovery. Thermodynamic calculations were performed to elucidate the hydrolysis behaviors of primary phases (f-CaO, C3S, and β-C2S) and the stability of secondary minerals in BOFS. The kinetic behavior and dissolution mechanisms of water-leached residues in acetic acid were further analyzed. Parametric experiments were conducted to evaluate the effects of the liquid-to-solid ratio (L/S), temperature, stirring rate, and acid concentration. Results show that the L/S is the dominant factor controlling Ca dissolution in both steps, while temperature exerts opposite effects: lower temperatures favor water leaching due to the exothermic nature of silicate hydrolysis, whereas higher temperatures enhance acid leaching. The proposed two-step route achieves a Ca recovery of 75.9%, representing a 7.6% improvement over direct acid leaching, while lowering acid consumption by ∼90%. This work provides mechanistic insight and process evidence supporting the efficient and sustainable utilization of BOFS for indirect CO2 mineralization.