Rheology of coal-water slurries prepared by the HP roll mill grinding of coal. Quarterly technical progress report No. 13, September 1, 1995--November 30, 1995

The objective of this research is the development of improved technology of the preparation of coal-water slurries that have potential for replacing fuel oil in direct combustion. Research accomplishments are summarized for: standardization of experimental procedures; investigation of effect of high-pressure roll mill/ball mill grinding on the energetics of fine grinding and the rheology of coal-water slurries prepared with such fines; study of aging behavior of slurries; and ways of improving rheology of slurries. The rheological behavior of slurries is a manifestation of particle-particle and particle-fluid interactions in the slurry. Improvement in the rheology of slurries could be brought about by suitably altering these interactions. The research directed towards investigation of the influence of co-addition of sodium hexametaphosphate and vacuum oil, with CoalMaster as the primary dispersant, showed that co-addition of the reagents significantly improved the rheology of coal-water slurries. Further research conducted in this quarter indicated that co-addition of reagents also improves the long-term rheological behavior of coal-water slurries.