Characterisation of liquid residue after collision between droplets and dust particles at micron scale

Dust easily triggers explosion accidents and occupational pneumoconiosis. Water mist is the most widely used dust suppression medium. However, due to the lack of scientific understanding of the adhesion state after dust-mist contact, the growth of mist dust suppression rate is facing bottlenecks. Through numerical simulation and experimental methods, the collision behavior of micrometer-scale droplet-dust particle was studied, and the relationship between the liquid adhesion amount on the dust particle surface and four types of collision behavior was obtained. The research results show that reducing the surface tension and contact angle of the mist droplets is beneficial to avoiding “rebound” behavior in low-speed collisions and also increases the liquid residue on the dust particle surface when “membrane splashing” behavior occurs. However, reducing the surface tension and contact angle of the mist droplets also lowers the critical collision velocity at which mist droplets rupture, resulting in a narrower range of speeds for “complete coalescence” behavior, which has a negative impact on dust suppression. This study also found that reducing the mist droplet size and increasing the mist droplet viscosity are both beneficial for increasing the viscous friction loss during the dust-mist collision process, thereby inhibiting “rebound” behavior and mist droplet rupture, and increasing the liquid adhesion amount on the dust particle surface after dust-mist interaction, significantly improving dust weight gain and settling effects. These findings can provide new ideas for the development of new dust suppressants and theoretical support for the optimization of spray dust suppression operating parameters.