A collaborative strategy based on high mineralization ability for rapid and effective treatment of acid mine drainage...

Global water quality is increasingly affected by acid mine drainage (AMD). The common methods used to remediate AMD are difficult to recover and utilize the high concentration of ions in water. In this study, a new method for AMD treatment was developed by chemical mineralization to hydroxyl sulphate iron minerals (HSIMs) followed by Ca-Al layered double hydroxides (Ca-Al LDHs) neutralization. It was found that 98.5% of iron and 29.2% of sulphate could be converted into 0.46 g of valuable HSIM in 200 mL of AMD containing 1190 mg/L iron, 110 mg/L manganese 2075mg/L sulphate ions and pH at 3.3 by adding 0.4 mL H₂O₂ and 0.5 g KHCO₃ in sequence. The resultant HSIMs, consisting of schwertmannite and jarosite, had a specific surface area of 5.34 m²/g, which could be used as heavy metal ion adsorbents. The method achieved a significant increase in the iron mineralization rate from 62.8% to 98.5% and recovered almost all of the iron, compared to forming only schwertmannite, which was essential for achieving better resource utilization in the AMD treatment process. With post-treatment of Ca-Al LDHs, the metal ions could be completely removed while maintaining sulphate concentration below the 250 mg/L highlighted by the World Health Organization. The combination of pretreatment of chemical mineralization to form HSIMs and post-treatment of Ca-Al LDHs offered a new approach for the rapid and effective treatment of AMD.