Study on environmental characteristics of sustainable biomimetic soil preparation and its application in gangue reclamation

To address the key challenges in achieving large-scale ecological reclamation of coal gangue in situ, this study utilized loess from a mining area in Northwest China to prepare a biomimetic soil. A new inorganic curing agent (ISA) was developed using coal-based solid waste and cement. The study investigates the influence of different ISA dosages and their interaction with Polyacrylamide (PAM) on the environmental characteristics of biomimetic soil, including geotechnical, ecological, and heavy metal stabilization properties. Results indicate that the addition of ISA significantly enhanced the geotechnical performance of the in-situ soil, with unconfined compressive strength exceeding 350 kPa when ISA content was above 6 %. Soil evaporation experiments and soil water characteristic curve tests demonstrated that a 6 % ISA dosage combined with 0.05 ‰ PAM could maintain soil's good water retention capability while preserving a bimodal pore structure. The biomimetic soil exhibited effective stabilization of heavy metals, including Pb, Zn, Cu, and As. The particles of PAM and the hydration products of ISA not only filled soil pores and increased soil strength but also adsorbed, encapsulated, and immobilized heavy metals. "Biomimetic soil-gangue" leaching test results confirmed that the gangue samples treated with biomimetic soil met the standards for Class III underground water in China regarding heavy metal leaching values. This study provides an effective solution for the large-scale in-situ disposal and resource utilization of gangue in Northwestern mining areas of China.