EVALUATION OF ROOF BOLTER CANOPY AIR CURTAIN EFFECTS ON AIRFLOW AND DUST DISPERSION IN AN ENTRY USING EXHAUST CURTAIN VENTILATION

摘要

Computational fluid dynamics (CFD) software has been used to aid in the design and improvement of the roof bolter canopy air curtain (CAC) system. A recent study conducted by the National Institute for Occupational Safety and Health (NIOSH) evaluated the roof bolter CAC system in a blowing face ventilation system demonstrating its effectiveness and illustrating the CAC protection zones. This study evaluates the roof bolter machine CAC while operating in an exhausting face ventilation system. This study considers two scenarios: (1) a roof bolting machine in the center of the entry for installation of the fifth row of bolts from the face, and (2) a roof bolting machine positioned close to the face for the installation of the last row of bolts. In both scenarios, the bolting machine is placed in an environment that contains 6.0 mg/m~3 of respirable dust and is ventilated by an exhaust curtain with 9,000 cfm (4.25 m~3/s) of air. This environment is used to simulate the roof bolter machine operating downstream of a continuous mining machine. Two operation positions are simulated at the same bolting location: dual drill heads in the inward position for two inside bolts and dual drill heads in the outward position for two outside bolts. The influence of the CAC on airflows and dust dispersion is evaluated with the CAC operating at 250 cfm (0.12 m~3/s) with dust reductions ranging from 39.5 to 82.8%. When the roof bolter operated close to the face, increasing CAC airflow was required for adequate protection since the dust reductions can be as low as 39.5%. Additional CAC airflows of 350 cfm (0.17 m~3/s) and 450 cfm (0.21 m~3/s) were evaluated and demonstrated that dust reductions increased to 59.7% (350 cfm) and 72.0% (450 cfm) for the worst location where the roof bolter operators located.