Slurry dewatering characteristics under synergistic mechanical pressure and electro-osmosis at constant current

Pressure-assisted electro-osmosis is effective for deep dewatering of high-moisture clay slurries, but the coupling effects of mechanical pressure and constant current under two-sided drainage, along with drainage redistribution and energy consumption, remain unclear. Using a self-designed apparatus with citric acid-modified kaolin (500 ∼ 900 kPa, 0.1 ∼ 0.3 A), combined with pure mechanical tests and Box-Behnken design, we analyzed dewatering kinetics, electric field evolution, cathodic/anodic drainage distribution, and specific energy consumption. Results show that current significantly advances the filtration-to-consolidation time threshold: at 700 kPa, 0.1 and 0.2 A reduce the mechanical threshold from approximately 90 min to 60 and 40 min, respectively; at 900 kPa, the threshold decreases from about 40 min to 38 and 26 min. Higher current increases early-stage dewatering rates, especially at the cathode; the cathode drainage proportion reached 41.4% at 180 min. Higher pressure reduces cake porosity and increases resistance, yielding diminishing marginal gains as current increases. Specific energy consumption rises with dry solid content, accelerating above 75%. Mechanical pressure mainly controls cake compaction and early-stage efficiency, while the electric field promotes deep dewatering via late-stage cathodic drainage, with a stage-dependent interaction.