Experimental study on the synergistic dust reduction of MNBs and surfactants

Spray dust suppression is a primary technological method for controlling coal mine dust. To enhance the wetting and adhesion of droplets to dust particles and improve the efficiency of spray dust suppression, a method of synergistic dust reduction by micro-nano bubbles (MNBs) and surfactants is proposed. This research focuses on MNBs, three different types of surfactants, and low-wetting anthracite coal. Experimental analysis is conducted to investigate the interaction between surfactants and MNBs in solution. The wetting capability of dust particles by the mixed solution of MNBs and surfactants is studied. Additionally, a spray dust suppression experimental platform is employed to compare the dust reduction efficiency of different types of surfactants in synergy with MNBs. The experimental results indicate that surfactants facilitate the generation of nanoscale bubbles, reduce the average diameter of MNBs, and the charge carried by surfactant molecules affects the potential of MNBs. Anionic surfactants decrease the bubble potential, while cationic surfactants elevate it, with non-ionic surfactants having a minimal impact on bubble potential. The presence of MNBs can temporarily reduce the surface tension of a surfactant solution, bringing it to the surface tension at the critical micelle concentration (CMC) but cannot surpass the surface tension beyond the CMC. The addition of low-concentration surfactant solutions to bubbles decreases the contact angle between dust particles and coal dust, while high-concentration surfactant solutions have the opposite effect. In general, the combined use of MNBs and surfactants is beneficial for improving spray dust suppression efficiency. However, extremely high surfactant concentrations lead to an excessive absolute value of bubble potential, enhancing the stability between dust particles and reducing dust suppression efficiency.