Enhancing arsenic immobilization in calcium arsenate slag through mineral phase reconstruction using copper slag via acid evaporation

• Published in: Process safety and environmental protection 2025-01, Vol.193, p.421-431
• Main Authors: Wang, Lanbin, Xie, Wenjie, Xu, Yangming, Zhang, Wenqi, Sun, Yan, Chen, Yu, Chi, Ruan, Du, Yaguang
• Format: Article
• Language: English
• Subjects: Calcium arsenic slag; Copper slag; Immobilization; Mineral phase reconstruction
• ISSN: 0957-5820
• DOI: 10.1016/j.psep.2024.11.053

Calcium arsenate slag (CAS) is a hazardous solid waste containing As which requires stabilization treatment. However, traditional techniques have deficiencies in terms of economic viability and stability, and there is an urgent need to treat it through environmentally friendly and effective methods. Herein, a novel strategy using copper slag (CS) as a multifunctional stabilizing agent for CAS is proposed. The presence of iron and silicate in copper slag contributes to the immobilization of As in CAS. The mineral phase of As in CAS was reconstructed through evaporation and crystallization treatment, forming a new stabilization system of kaatialaite-calcium silicate. Molecular dynamics simulations had shown that the combination of kaatialaite and calcium silicate enhanced the stability of As in CAS and limited its diffusion. The As concentration in CAS's toxicity characteristic leaching procedure (TCLP) had been reduced from 195.91 mg/L to 0.26 mg/L, with an As immobilization efficiency of 99.71 %, which met the landfill standards (GB 18598—2019, As＜1.2 mg/L). Further, this method achieves waste treatment by waste, providing an efficient and cost-effective solution for the stabilization treatment of As-containing solid waste. [Display omitted]