The frictional characteristics of coal particles

This paper describes what are argued as the interfacial frictional characteristics of typical coal particles, both in air and in an aqueous medium, when they are slid over various counterfaces. These characteristics have been deduced by causing a collection of coal particles to slide against a range of relatively smooth substrates under the action of gravitational forces. This was achieved by containing the particles in different cylinders which were rotated about their major axes of symmetry. Data are reported for a number of experimental variables, the most important cf which was the weight of the particle bed. The experimental data have been rationalized, in part, using an extension of the adhesion model of friction which attributes the measured wall friction to the estimated contributions from the Individual particle-wail friction characteristics. In addition, frictional data are given for single-particle-wall contacts. A number of facets inherent in the assumptions developed for this model are examined and discussed.