Recovery of Cu2+from acid mine drainage by bentonite-carbide slag composite particle through spontaneous film formation-crystal self-growth-fixed mineralization

In this study, a novel bentonite-carbide slag composite particle (BCS) with endogenetic crystal ion of OH- was prepared by using bentonite and carbide slag as raw materials to treat acid mine drainage containing Cu2+. Macroexperiment, microtest, and theoretical analysis were adopted to reveal the characteristics and mechanism of BCS for the recovery of heavy metal ions from acid mine drainage (AMD). The results showed that the solution around the BCS can spontaneously form a spherical colloid film interface layer, and Cu2+ can be recovered by self-growth film formation and fixed mineralization through the synergistic effect of adsorption, precipitation, induced crystallization, and self-growth mineralization. Two stages, including liquid film formation and selfgrowth mineralization, existed in the formation and mineralization of mineralized films. This study provided a new treatment perspective for the removal and fixed mineralization recovery of heavy metal ions in AMD. It also provides a scientific theoretical basis for the spontaneous film formation, crystallization, self-growth, and fixed mineralization recovery of heavy metal ions in AMD by the endogenetic crystal ion of OH- in BCS.