261 / 2023-09-30 22:42:50

Study on the ratio parameter optimization of bulk coal-based solid waste low-water filling material

Coal-based solid waste; low-water filling; paste filling material; response surface methodology; hydration mechanism

The aim of this study is to investigate the influence of the water-reduction ratio on the flowability and strength of bulk coal-based solid waste paste materials in the western Ningdong mining area. This research provides important fundamental parameters for addressing issues such as water scarcity and the challenging disposal of solid waste in western coal mining regions. Desulfurized gypsum, fly ash, and cement were selected as the main raw materials. Microscopic morphology and component analysis of the raw materials after single compaction were conducted using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical parameters were determined to optimize the mixture composition. A Box-Behnken design with three factors (A: desulfurized gypsum content in the solid, B: mass ratio of fly ash to cement, C: slurry concentration) at three levels was employed using Design-Expert software, resulting in a total of 17 mixture compositions. A response surface regression model was established to analyze the impact of single and multiple factor interactions on the strength and flowability of the low-water paste material (slurry mass concentration ranging from 72% to 76%). The research results indicate that the BC interaction significantly influences the strength of the filling material, with factor B being the most significant single factor affecting strength, and factor C being the most significant single factor affecting flowability.Furthermore, the optimal mix ratio was determined based on flowability experiments, which consisted of 50% desulfurized gypsum content, a fly ash-to-cement ratio of 2, and a slurry concentration of 72%. This study provides a scientific basis for the design and application of low-water bulk coal-based solid waste filling materials, which is of great significance for achieving efficient resource utilization and sustainable environmental development.