Study on hydrophobic floc structure of coal particles based on fractal simulation

Utilizing the Matlab platform, two-dimensional diffusion-limited aggregation and three-dimensional diffusion-limited cluster aggregation models were established to simulate the hydrophobic flocculation of coal particles. The formation process of flocs aggregated by monomer particles and small groups was simulated from both plane and space perspectives. The gyration radius fractal dimension increased from 1.401 to 1.539 in the DLA model and from 1.623 to 1.729 in the DLCA model, indicating that the floc morphology gradually stabilized and the structure became increasingly regular during the hydrophobic flocculation process. The porosity of DLA increased from 0.762 to 0.851, indicating that the dendritic structure of flocs formed a spatial shielding effect on the planar structure, which prevented the particles from entering the flocs. In contrast, the porosity of DLCA first increased from 0.506 to 0.611 and then decreased, stabilizing at approximately 0.53, indicating that small groups filled the internal voids of flocs in the spatial structure, leading to a gradual increase in floc density. The surface fractal dimension and density of flocs were calculated using the surface fractal and hydrostatic sedimentation-terminal velocity theories, respectively, confirming the conclusions drawn from the simulation analysis.