Characterization of coal water slurry prepared for PRB coal

Powder River Basin (PRB) coal, which accounts for over 40% of the coal consumed for power generation in the United States, was investigated for preparation of coal water slurry (CWS). The static stability and rheology of the CWS were characterized as a function of loading. The coal loading was varied from 30% to 50% and both ionic (sodium polystyrene sulphonate (PSS)) and nonionic (Triton X-100) surfactants were employed as additives. The addition of PSS to PRB slurries was found to yield poor static stability. On the other hand, Triton X-100 was found to be an effective surfactant, reducing the sedimentation by more than 50% compared to the one without surfactant in 45% CWS. Adding Triton X-100 reduces the viscosity of the CWS for coal loadings of 30% and 40%. Although the viscosities for coal loading of 42.5% and 45% are higher when Triton X-100 is added, the static stability is significantly better than for samples without surfactant. The highest coal loading for PRB slurry with acceptable viscosity for pumping is 42.5%.