Abstract:In response to the problems of low economic efficiency, poor filling effect, and inability of the filling body to be capped by cement cementitious material for cementitious filling of superfine tailings in a gold mine, low-cost mine filling cementitious materials were developed by using local industrial solid waste such as fly ash, slag, and desulfurization gypsum. Firstly, based on the analysis of physical and chemical properties of raw materials, a Box-Behnken test design based on the response surface method was used to carry out 17 sets of ratio optimization tests; secondly, a quadratic polynomial prediction model with the 28-d compressive strength of the filler as the response target was constructed, and the primary and secondary relationships of the test factors on the response target were investigated by combining ANOVA and response surface to optimize the cementitious materials. Finally, the types of hydration products and strength development laws in the composite gelling system were elucidated by means of microscopic tests such as X-ray diffraction analysis (XRD), Fourier infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The test results show that the compressive strength of the filled body is not only influenced by a single factor, but also by the interaction of multiple factors. The interaction between cement and fly ash has a significant effect, followed by the interaction between cement and desulfurization gypsum, and the interaction between fly ash and desulfurization gypsum has no significant effect. The optimum ratio of cementing materials is 27% cement, 48% fly ash, 23% slag, 2% desulfurization gypsum, 3.5% water glass and 1.5% mannite, and the 28-d compressive strength of the filler is 3.58 MPa, which meets the requirements of mine filling and mining. The main hydration products of the composite gelling system are chalcocite and C-S-H gel, and with the hydration reaction, the interlocking viscous structure of the two forms a solid spatial network system, which makes the filling body maintain high strength performance.