Influence of dispersants, surfactants, and stabilizers on formulation and rheology of coal water slurries from Indian high ash coal

Abstract

Indian coals typically contain high ash. Using raw coal poses transportation, and efficient burning problems; their slurry form may offer a viable solution for it. CWS, a non-Newtonian fluid, requires additives for achieving desired stability and rheological properties. In this study, base 52 wt% CWS, and six additive-modified 52 wt% coal slurry samples prepared to identify better additives. Coal powder of 53–74 μm particle size range (SJR2) used to prepare seven slurries. Additives include dispersants [Poly (styrene sulfonic acid) sodium salt (PSS); Sodium lignin sulfonate (SLS)], surfactants [Sodium dodecyl sulfate (SDS); Cetyltrimethylammonium bromide (CTAB)], and stabilizers [Xanthan gum (XG); Guar gum (GG)]. A simple CWS prepared by mixing coal powder in distilled water at 600 rpm for one hour, then kept standstill for 12 h at room temperature. Similarly, six more 52 wt% coal slurries prepared by firstly making six additive solutions then mixing coal powder (SJR2), separately, to these solutions. As per requirement; individual as well as comparative characterizations, and rheological tests done for raw coal and all prepared slurries (dried and wet) to ascertain their physical, chemical properties along with structural formation and rheological behavior. Changes occurred in apparent viscosity, and shear stress of prepared slurries studied at 30 °C, at varying shear rate of 1–1000 s⁻¹. Herschel–Bulkley rheological model was used to validate experimental data. Characterization, and rheological results showed that PSS solⁿ. (1 %), SDS solⁿ. (1 %), and XG solⁿ. (0.1 %) were found better for the respective desired purposes.