CFD ANALYSIS OF AIRFLOW PATTERNS IN HIGH MINING AREAS OF ROOM-AND-PILLAR COAL MINING

This thesis studies airflow patterns in the face area of a typical room-and-pillar mining area, using Computational Fluid Dynamics (CFD) modeling. This research is designed to develop a scientific understanding of airflow distribution in room-and-pillar mining areas that is fundamental to developing engineering controls. The overall goal of the study is to develop improved engineering controls to minimize dust exposure of mine workers in the face area. Dust exposure can be a health hazard in underground coal mining industry based on historical data of coal workers\u27 pneumoconiosis among underground mine workers. Current regulatory dust exposure standards of 1.5 mg/m3, averaged over an 8-hour period, have been recently revised with approval of new MSHA standards in April of 2014. Mining companies are currently seeking new technologies in order to comply with the new dust standards. Since mining geometries are complex and do not lend themselves to closed-form analytical solutions, CFD numerical modeling approach was used to develop an understanding of airflow distribution in the face areas. Since previous studies had focused on some cuts in mining heights of less than 2.4 m (8-ft), this study was performed for high mining areas of 4.2 m (14-ft). Such mining heights are very common in longwall mine development areas, particularly in the State of Illinois. The primary goal was to identify major differences in airflow between the two mining heights and how they affect development of engineering controls for minimizing dust exposure. Simulations were done using ANSYS software such as DesignModeler for modeling and meshing and FLUENT for calculations. Recirculation (RC) and low air velocity (LAV) zones were located for straight deep cut, straight deepest cut, cross-cut right, cross-cut right mine through, left turn cross-cut, and left turn cross-cut mine through for low mining height (LMH) and high mining height (HMH) with varying air quantity at the end of the line curtain (ELC). Air at the ELC was adjusted to achieve a ratio of 0.85, 1.00 and 1.15 over the wet scrubber fan (WSF) discharge capacity. Results show that the air velocity in HMH case is much lower than for the LMH. In addition, the location of RC and LAV zones differ based on mining height and air quantity at the ELC. Furthermore, lower air quantity at the ELC causes the air exhausted by the WSF to recirculate back to the face area in order to satisfy the WSF requirement. Recommendations to deal with these differences are formulated