Mechanical properties and leaching behavior of modified magnesium slag cemented aeolian sand paste backfill materials

[Display omitted] •Modified magnesium slag is used to prepare the filling material (MFPB).•MFPB has excellent early and long-term mechanical properties.•The leaching behavior of MFPB raw materials were investigated.•Three different methods were used to assess the leaching risk of MFPB.•MFPB is a non-polluting, sustainable and environment-friendly filling material. Magnesium slag is a by-product of magnesium smelting industry, and its massive discharge has seriously threatened human health and ecological environment. In order to solve the environmental problems caused by magnesium slag, a mine backfill material (MFPB) was prepared with modified magnesium slag-fly ash cemented aeolian sand in this paper, and the long-term mechanical properties and leaching behavior of MFPB were investigated. The strength of the MFPB increased with increasing curing time, and the strength reached 4.984–17.140 MPa at 300 d, with FA20 having the highest strength. In terms of environment: (1) Except that FA has certain risks, the leaching levels of other raw materials meet the class III groundwater standard (III-GQSL) in GB/T 14848–2017. (2) The leaching level of MFPB based on the SPLP procedure meets the III-GQSL, and has a significant stabilization/solidification effect on hazardous elements; (3) The results of the LEAF test showed that pH and liquid–solid ratio were important factors affecting the leaching of harmful elements in MFPB. MFPB has good mechanical properties and environmental friendliness, and has the potential for large-scale safe application in mine backfilling.