An investigation of booster fan placements in a large opening underground stone mine utilizing CFD

The optimization and planning of the mine ventilation system is a key component of mine operation given that ventilation related costs can range between 20% and 50% of the total operating cost of the mine. In large opening mines (LOMs) utilizing perimeter ventilation schemes minimal guidance is available for determining optimal booster fan (BF) placements. A ventilation survey was conducted and published previously by the author which established a CFD model for a section of an underground room and pillar large opening limestone mine. In this work the previously created CFD model was utilized to investigate a total of 15 BF positions with a focus on recirculation patterns, overall airflow within the BF entry, and airflow around face area. It was found that the maximum airflow around the face areas can be achieved with fan positioned on the same side of the entry as face area; with the maximum airflow through the BF entry being achieved when the fan is placed in the center of the entry on the upstream side of the pillar line. The recirculation percentages were similar in all cases reaching a maximum between 35%-40% of the total air movement. However, the highest recirculation percentages also facilitated, via air entrainment, the highest airflow magnitudes through the BF entry. The booster fan’s ability to stimulate airflow through adjacent entries was found to be reduced by approximately 30% for each adjacent entry. Therefore, the recommendation was given to position the BF within 3 entries of the face to achieve adequate airflow.