Preparation of high-performance and environmentally friendly superfine tailings cemented paste backfill using cellulose nanofibers

Backfilling using solid waste technology is a prominent direction for low-carbon mining and clean production in mines. To achieve high-quality cemented backfilling using superfine tailings, renewable cellulose nanofibers (CNF) are introduced to modify superfine tailings cemented paste backfill (SCPB), and a range of experiments are implemented to comprehensively investigate the effect of CNF on key properties of SCPB, such as mechanical properties, rheological properties, microstructure, and thermal stability. The results show that a proper amount of CNF content (0.1 %) can improve mechanical properties for SCPB, and there is little difference in the enhancement effect at all curing times. Simultaneously, the huge specific surface area of cellulose nanofibers (CNF) and numerous hydroxyl functional groups contribute to increased yield stress, apparent viscosity, and thixotropic in SCPB. The microanalysis results demonstrate that CNF introduces additional nucleation sites in the SCPB hydration reaction system, promoting the generation of the Si-O-Al bond and higher-polymerized C-S-H, thus accelerating the hydration reaction. On the other hand, the filling and bridging effects of CNF can improve the compactness of SCPB and prevent microfracture expansion, which are the key factors for CNF to enhance the mechanical properties of SCPB. The kinetic study of thermal analysis shows that CNF could increase the activation energy of hydration products in SCPB, thus improving its thermal stability. The research provides new ideas for green backfilling of solid waste and efficient utilization of superfine tailings.