The effect of anionic dispersants on the moisture distribution of a coal water slurry

Coal water slurry (CWS) was prepared from lignite washery tailings. Its moisture content can be subdivided into two forms: free water (surface adsorption water) and bound water, i.e., interparticle, capillary, adhesion and internal adsorption water. The effect on moisture distribution of three distinct dispersants was studied through thermal drying and TG–DSC analysis. A new test method combining thermal drying and bond strength analysis was put forward for a thorough moisture distribution. The new method showed reasonable results and arrives at the same conclusion as the TG–DSC method. The addition of dispersants increased the free water content and decreased the bound water content, in particular those of interparticle and capillary water. Also there was a slight decrease in total moisture, compared to CWS prepared without dispersant. The moisture distribution showed its biggest change with dispersant CLS (calcium lignosulfonate), followed by dispersant NDF (a co-polymer of methylene naphthalene sulfonate, styrene sulfonate and maleate), and ended up with NNO (sodium methylene bis-naphthalene sulfonate).