Improving the Storage Stability of Coal Water Slurries Use of a pH-Responsive Thickener

Coal water slurries (CWSs) are considered to be a new form of fuel that can alleviate the environmental and safety issues associated with use of bulk solid fuel. However, CWSs does not always fit into existing solid fuel supply and storage chain. In this study, a novel method to control CWSs viscosity using pH-responsive thickener was proposed, offering the advantages of improved storage stability and on-demand viscosity control, thus allowing CWSs to be used as a c for a variety of applications. This study investigates the effects of additives and pH on the viscosity and storage stability of CWSs. Poloxamer 407, polynaphthalene sulfonate formaldehyde (PNSF), and a copolymer containing pigment-affinic (PA) groups were used as dispersants to lower CWSs viscosity. Xanthan gum, a modified acrylic polymer (MAP), and carbomer were used as thickeners for assessing the storage stability and fluidity of CWSs based on viscosity changes. Optimal viscosity reduction was achieved by the addition of PA. A viscosity of 7000 cP was achieved by the use of carbomer, with small amount comparable to 27.3 wt% of MAP and 22.7 wt% of Xanthan gum. Moreover, the carbomer-containing CWSs exhibited high storage stability in a 360-h stability test, retaining 84.3% of the original baseline coal content. pH-dependent viscosity changes were observed only in carbomer-containing samples.