Rheology of coal-water slurries prepared by the HP roll mill grinding of coal. Quarterly technical progress report No. 3, March 1--May 31, 1993

Abstract

By comparing the rheological behavior of Pittsburgh No. 8 coal-water slurries obtained when using the Haake RV- 12 viscometer with both the MV-II and MV-DIN sensor systems, we found that the MV-DIN sensor system performs better than the MV-11 sensor system for slurries with high solids content. For studying the effect of chemical additives on the rheology of coal-water slurries, the Triton X series of nonionic surfactants was used. The addition of these nonionic surfactants significantly reduces the viscosity of the slurries, especially at higher reagent additions (1 wt %). Those Triton X nonionic surfactants having a larger number of ethoxy groups in the molecules are more effective for reducing the viscosity of a slurry than the surfactants with a smaller number of ethoxy groups because of the hydrophilic nature of ethoxy groups. In studying the effect of the solids content in the presence of 1 wt % Triton X-405 (dry coal basis), slurry viscosity was found to increase sharply with increasing solids content. Those slurries with high solids content (66 wt % and 67 wt %) have a significant yield stess, even at an addition of 1 wt % of Triton X-405. The maximum solids content of slurries that could be used in the presence of 1 wt % Trition X-405 is 67 percent.