Evaluating the influence of coal particle size gradation on the properties of coal–water slurry

This paper presents a comprehensive evaluation of the influence of coal particle size gradation on the properties of coal–water slurry (CWS), including coal concentration, flowability, stability, and rheological behavior. The research findings indicate that coarse coal particles have a dominant effect on improving the coal concentration of CWS, while fine coal particles significantly contribute to enhancing the flowability and stability of CWS. Also, a gradation approach incorporating both coarse and fine components with continuous particle size distributions was explored, successfully achieving a high performance CWS with a high coal concentration of 66.12 wt%, a flow time of 13.37 s indicating excellent flowability, and a water separation rate of 3.49 wt% after standing for 7 days, demonstrating good stability. Furthermore, the validity of these research results was confirmed by zeta potential analyses and scanning electron microscopy (SEM) investigations. [Display omitted] •High performance coal–water slurry (CWS) can be achieved by particle size gradation.•The respective roles of coarse and fine coal particles in CWS system are elucidated.•Using coarse particles with a wide size distribution has some unique advantages.•The aggregation structures formed by fine particles could enhance stability of CWS.