Foam for coal dust suppression during underground coal mine tunneling

Dust is a major threat to worker safety and health during underground tunneling, and dust suppression using foam has proved to be efficient in restricted spaces. A performance test using foam showed that the addition of a foaming agent to water decreases the contact angle with coal dust by 67% while increasing the wettability rate 30 fold. The resulting foam has a maximum apparent viscosity of 751 mPa s at an expansion ratio of 30. This foam suppresses dust by wetting and capturing the dust particles by adhesion. A foam preparation system that automatically adds the foaming agent by self-suction was installed on a foaming device on a roadheader excavating a tunnel. The results showed 87.9% and 76.0% efficiencies for total and respirable dust suppression near the roadheader driver's position, which were 2.1 and 2.37 times higher than the efficiencies for water spraying. Using foam suppression, the driver's visibility was improved from less than 0.5 m to 7.5 m, 1.8 times longer than when using water spraying. This dust suppression method can potentially be applied in power plants, quarries, and other dusty environments.