Effects of surface chemical and electrochemical factors on the dewatering characteristics of fine particle slurry

Coal suspension was employed in vacuum filtration process to observe the dewatering characteristics of fine particle slurry. Generally, as the size of coal particle decreased, the specific resistance was increased and dewatering efficiency was reduced. Slurries containing the particles with a broad size range had a higher compressibility and could not filter easily if modified process was not applied. This study also investigated the effects of an anionic and a cationic surfactants on filterability by examining the surface property of coal particles. Dewatering was observed to be more efficient when cationic surfactant was used. To improve dewatering rate and to reduce the final moisture content of slurry, electrodewatering combined with vacuum filtration was applied. The effects of some different variables were examined, such as the type of surfactants, electrode (arrangements and materials), and the electrical parameters (voltage and current). By application of electrodewatering, dewatering efficiency was found to be enhanced compared to conventional vacuum filtration. The specific resistance was represented to be 0.3815 at 0 V, whereas it was shown to be 0.2113 and 0.1631 at 20 V under direct current and alternative current, respectively.