Date of Graduation


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The study in this dissertation attempts to alleviate the problem of inefficient cutting and respirable dust production by continuous miners. It involves identification of the important parameters that affect coal fragmentation, design of an Automated Rotary Coal Cutting Simulator (ARCCS) and study of the effects of these parameters on coal fragmentation. Two sets of experiments were conducted, first, multiple bit experiments to establish the experimental procedures and study the microscopic fracture surface and second, single bit experiments to investigate the significance of the important parameters based on a statistical design called the two way factorial design. From the multiple bit tests a relationship has been established between the size distribution and the fracture surface for bit type, bit spacing, depth of cut, equivalent in situ confining pressures and cleat orientation. It was concluded that the key to achieving efficient coal fragmentation is to limit the degree of bit-coal interaction by chosing the space to depth ratios that cause maximum breakage of the coal boundary between the bits. Data collected from single bit experiments were used in building a statistical model for the independent variables: resultant force, specific energy and fine size distribution.