Parametrical design and optimization of a reverse circulation drill bit for dust control

The reverse circulation down-the-hole air hammer drilling (RC-DTH) method is renowned for its efficiency in hard rock formations and exceptional dust control performance. It presents opportunities for cost-saving, efficiency improvement, energy conservation, and environmental protection. Reverse circulation drill bits are critical components of this method. This study focused on the air reverse circulation regime, investigating various geometric parameters of the RC drill bits through computational and experimental methods to enhance its dust control performance. Results indicate that increasing the layers of suction nozzles, enlarging the diameters of the suction and mixing nozzles, and optimizing the input airflow rate can effectively channel airflow toward the central passage of the drill tool. Consequently, this optimization significantly improves the dust control performance of the RC drill bits. Conversely, increases in the flushing nozzle diameter and alterations in the suction nozzle location have detrimental effects on the dust control capability of the RC drill bits. Field tests were conducted at the Yuan Jiacun iron mine, affiliated with Taiyuan Iron and Steel (Group) CO., LTD. The field tests demonstrate that the optimized RC drill bit exhibits excellent dust performance.