Effect of mixture of a non-ionic and a cationic surfactant for preparation of stabilized high concentration coal water slurry

Abstract

The rheological behavior of high ash Indian coal samples was investigated by blending fines (<38??m) with four distinct coarse fractions (212?300??m, 90?300??m, 150?212??m,75?150??m). The blended four representative samples were labeled as S-1, S-2, S-3, and S-4, respectively for the study. The flow behavior of coal water slurry (CWS) was characterized with a mixture of non-ionic surfactant saponin from shikakai and a cationic surfactant di-docyl ammonium bromide (DDAB) at different coal loadings, Ph, and dispersant dosages. The concentration of DDAB in saponin was optimized on the basis of surface tension and apparent viscosity values. The non-Newtonian flow behavior of CWS in the studied range of concentrations (58?70% by weight) was fitted well to Bingham plastic model. A suitable mechanism of interaction between mixture of saponin and DDAB on coal surfaces was given on the basis of Zeta potential measurement.