A new design of foaming agent mixing device for a pneumatic foaming system used for mine dust suppression

To overcome the drawbacks of the conventional foam technology used for dust suppression, including large pressure loss, high water pressure and low driving pressure, a new pneumatic foaming system is introduced. Then an original design of foaming agent mixing device is proposed, and its performance is investigated and evaluated under different pressure compensations. Experimental results show that the maximum absorption amount increases by 2.9–6.7 times at a pressure compensation of 0.04–0.2 MPa compared with no pressure compensation. The pressure loss and pressure fluctuation both reduce significantly with increasing pressure compensation. The critical outlet pressure increases by 30.4–240%. Field application indicates that the proposed mixing device ensures the reliable addition of foaming agent used for foam dust suppression. The effect of foam on dust suppression is remarkable, and the economic cost of foam is low. Therefore, there is reason to believe that the new mixing device will greatly promote foam technology to be widely used for suppressing dust in underground coal mines.