Effect of dispersing and stabilizing additives on rheological characteristics of the upgraded brown coal water mixture

Upgraded brown coal water mixture (UBCWM) preparation by using an Indonesian upgraded coal produced by upgraded brown coal (UBC) process, was carried out to study the effect of dispersing and stabilizing additives on theological behavior of the UBCWM. Three kinds of anionic dispersing additives, naphthalene sulfonic formaldehyde condensate (NSF), poly (meth) acrylate (PMA) and poly styrene sulfonic acid (PSS) and three kinds of stabilizing additives, carboxyl methyl cellulose (CMC). rhansam gum (S-194) and gellan gum (S-60) were used in this study. Results indicate that the addition of NSF 0.3 wt.% together with S-194 0.01 wt.% is effective in preparing UBCWM with good slurryability and stability, based on its theological characteristics with the apparent viscosity at shear rate of 100 s(-1) and yield stress at zero point of shear rate. The theological behavior of all of the UBCWM that prepared, exhibits non-Newtonian Bingham plastic. From the economical point of view. the price of S-194 is expensive. Oil the other hand, CIVIC is cheap and abundant. Therefore, the addition of CMC 0.01 wt.% together with NSF 0.3 wt.% is also effective in preparing UBCWM with good fluidity and stability. (C) 2008 Elsevier B.V. All rights reserved.