Influence mechanistic of rheological properties and floc structure on coal slurry sedimentation and dewatering

Flocculation and sedimentation of coal slurry are critical solid–liquid separation processes in coal preparation, and the floc structure and rheological properties of the slurry affect subsequent dewatering performance. Fine coal slurry is treated with cationic polyacrylamide (CPAM), anionic polyacrylamide (APAM), and the synthesized flocculant GgB14 to investigate the effects of flocculant dosage on settling, dewatering, and rheological properties.The results show that CPAM promotes rapid settling and forms large, compact flocs with significantly higher yield stress and consistency index. The elasticity and structural strength of the slurry are enhanced with increasing dosage, whereas the filter cake moisture content remains as high as 30.08%. In contrast, APAM and GgB14 produce relatively loose flocs with lower yield stress and loss factor, resulting in filter cake moisture contents of approximately 18% and superior dewatering performance. Regression analysis indicates that the consistency index (K) is strongly correlated with filter cake moisture content (R² = 0.89), suggesting that it can serve as an indirect indicator of dewatering performance. These findings clarify the relationship among floc structure, rheological properties, and dewatering performance of coal slurry and provide a theoretical basis for flocculant selection and dewatering process optimization.