Abstract:
Hydroxypropyl methylcellulose (HPMC) has proven effective in modifying slurry properties and is widely used in cement-based materials. However, research on HPMC application in coal gangue slurry remains limited, with existing studies primarily focusing on preliminary investigations of its macroscopic effects while lacking systematic analysis of its working mechanisms. This paper systematically investigates the evolution of slurry’s macroscopic properties with varying slurry concentration, gangue gradation, and HPMC dosage through slump flow and sedimentation coefficient tests. The mechanisms of HPMC are elucidated using scanning electron microscopy (SEM) and polarized light microscopy (PLM) observations. The results show that the slurry concentration, the upper limit of gangue particle size, and the HPMC dosage all have a significant impact on the fluidity and sedimentation coefficient. The degree of influence is ranked as follows: slurry concentration > upper limit of gangue particle size > HPMC dosage. The fluidity loss rates
LA,
LB, and
LC are 1.12, 0.87, and 0.69, respectively, indicating that changing the slurry concentration, the upper limit of gangue particle size, and the HPMC dosage to improve the stability of the slurry have an adverse impact on the fluidity of the slurry in the order of slurry concentration > upper limit of gangue particle size > HPMC dosage. Compared with the methods of adjusting the concentration or changing the gradation, the addition of HPMC significantly reduces the increase in flow resistance while maintaining high stability, achieving a synergistic optimization of stability and fluidity. The optimized slurry ratio is as follows: the upper limit of gangue particle size is 2-3 mm, the HPMC dosage is 0.045%, and the slurry concentration is 76%. Mesostructure analysis shows that HPMC connects discrete fine particles into a three-dimensional flocculent network structure through adsorption bridging, which forms a “mechanical skeleton” throughout the slurry system, effectively counteracting the settlement trend of coarse particles and significantly improving the stability of the slurry. The research results provide theoretical support and optimization basis for the engineering application of coal gangue slurry.