Coal and Gangue Underground Pneumatic Separation Effect Evaluation Influenced by Different Airflow Directions

Coal and gangue underground pneumatic separation is of key importance for green mining. Two kinds of arrangement schemes for high-pressure value used in pneumatic separation system are proposed in this study. Pneumatic separation effects are examined under different arrangement of high-pressure value. Here, theoretical pneumatic separation distance formulas of mineral particles affected by different airflow directions are derived and validated by a series of numerical simulations and orthogonal experiments. In the following analysis, the effects of gangue diameter (d), conveyor velocity (V-0), and the height difference between conveyor belt and air nozzle (h(p)) are mainly considered. The numerical simulation and experimental results indicate that pneumatic separation effects under the condition of u and V-0 being in the opposite direction will be better than that of.. and V-0 being in the same direction. The pneumatic separation distance Delta S shows a decreasing trend with the increasing of the three factors. The study also shows that gangue diameter has the most significant influence on separation distance, followed by conveyor velocity V-0 and height difference h(p).