Immobilization of Lead and Zinc in Tailings Sand Using a Stabilizer Synthesized from Granite Sawdust for Mine Remediation

Improper disposal of granite sawdust from stone processing and heavy metal-containing tailings sand can pose severe threats to the environment and human health. Based on their physicochemical properties, granite sawdust was used to synthesize a zeolite-based stabilizer (GFAS) for immobilizing lead (Pb) and zinc (Zn) in tailings waste. The stabilizer was prepared through an alkali fusion–hydrothermal method, followed by phosphoric acid modification. Characterization by XRD, SEM-EDS, and BET revealed that GFAS possesses a Na-P1 zeolite structure (Na6Al6Si10O32) with a micro-mesoporous texture and a specific surface area of 35.00 m2/g, representing a 10-fold increase over raw sawdust. The cation exchange capacity (CEC) of GFAS reached 57.08 cmol+/kg, a 116-fold enhancement. The stabilization mechanism involved synergistic physical adsorption, chemical precipitation (e.g., Pb3(PO4)2, Zn(OH)2), and ion exchange. This study presents a sustainable “waste-treats-waste” strategy for effectively reducing the mobility of heavy metals in tailings waste, thereby contributing to the remediation of seepage from tailings pond foundations.