Analysis of dust concentration patterns in high-production longwalls

This thesis analyzes the distribution of respirable dust concentrations on high-production longwall faces during the full production cycle. A sampling procedure was designed to allow full utilization of the capabilities of Real-time Aerosol Monitors (RAM1s) in order to assess the space and time dependences of the dust concentration distribution. A relational database model was developed to store and analyze the extensive data. The main findings of this research are: (1) Instantaneous respirable dust concentrations increase downwind of dust sources. (2) The velocity of the respirable dust is significantly smaller than the velocity of the carrier air. (3) The difference between the air velocity and the respirable dust velocity has a significant impact on the increase of instantaneous respirable dust concentration downwind of the dust sources. (4) The production rate and shearer cuffing speed do not correlate with respirable dust concentrations. (5) The extended longwall face and panel lengths beyond the traditional dimensions do not impact respirable dust concentrations on the face. (6) Other face conditions, such as the efficiency of dust suppression devices and the amount of roof rock that is cut during the production cycle, have a significant impact on dust concentrations on the longwall faces.; The findings required the development of a two-phase mathematical dust transport model in order to predict dust concentration distributions on the longwall faces. In order to validate the model, a procedure to measure the dust transport parameters such as intensity of each of the dust source and dispersion coefficients during the full production cycle was developed. The data from mine experiments during the full production cycle were utilized to validate the two-phase respirable dust transport model. The model is useful for dust control planning, as well as for the assessment of the impact of operating parameters on the respirable dust levels on longwall faces.