OFR-64-79 Relationship Of Coal Properties And Machine Parameters To Continuous Mining Machine Cutting Rates

This report is in three parts. The first part presents a review of theoretical models which have been developed to study removal operations for various types of materials. In the second part, a brief summary is given of coal cutting research. The majority of this work has been carried out in Britain using chisel type bits rather than the conical picks which are in general use in this country. However, a comparison of specific energies measured for conical picks in the laboratory and in the mine shows very encouraging correspondence. In the third part of the report, analytical models for coal cutting by picks are suggested. An extension of the British "tensile breakage" theory, developed for chisels, is given for picks. The role of crushing and cutting in coal removal is discussed as a theory which combines the two processes is shown to give reasonable predictions for specific energy requirements. Finally, directions in which the existing theory could be improved are presented and the need for further research is emphasized.