Activated electrolytic manganese residue-based environmental materials for mine remediation: Performance and mechanism

To address the environmental hazards of electrolytic manganese residue (EMR) accumulation and the urgent need for ecological restoration in mining areas, we developed an innovative method for creating pit restoration materials (S-EMRs) using alkaline-excited EMR via mechanical ball milling. Black liquid (BL) was used as a base exciter and EMR as the precursor. With a BL dosage of 35%, alumina as the milling medium, a speed of 500 rpm, and milling for 20–35 min, we achieved an S-EMR compressive strength of approximately 30 MPa after 14 d—six times higher than that in conventional cement curing (C-EMR). This method also stabilized contaminants such as Mn and NH₄⁺ by over 10-fold. The self-cementation and formation mechanisms of the S-EMR were clarified through chemical characterization and geochemical modeling. Over 3 y of monitoring and plant experiments have shown that S-EMR ensured the long-term stability and ecological restoration of mining areas. Remarkably, it enhanced microbial diversity and biophilicity, improving tomato seed germination by over 90% compared with that in control. This study presents a sustainable and innovative solution for the green cycle rehabilitation of Mn mining areas with significant potential for engineering applications.