Control of Dust Generation

"The main objective of this research is to identify the mechanisms of control of respirable dust generation in coal mines. Full understanding of the mechanics of crack propagation in coal is of fundamental importance in studies of the generation and control of respirable dust.The main objectives of this fracture investigation are: 1) to determine reliable data on the fracture toughness of coal as a parameter controlling unstable crack propagation; 2) to determine fracture propagation velocity in coal providing data on the terminal velocity at which crack bifurcation occurs and fine fragments of coal material are generated; and 3) to apply the critical strain energy density criterion to model mixed mode crack propagation in coal.The development of the protocol, laboratory procedure and equipment necessary to conduct an extensive mixed mode fracture toughness testing program has been completed. About 80 mixed mode fracture toughness tests, 10 good fracture velocity records and over 50 fracture surface examination with the SME are available. The details of the mixed mode fracture toughness testing are available in a paper titled, ""Development of Mixed Mode Testing System for Geologic Materials"" which is available from the center. The average fracture toughness and critical strain energy density values for the three seams investigated to date are included in the attached Figures 71, 72, 73."