An enhanced spray dust suppression method by micro⁃nano bubbles

To improve the dust capture performance of fog droplets and the spray dust suppression efficiency，a method of utilizing micro⁃nano bubbles to enhance the spray dust suppression is proposed. Taking micro⁃nano bubble water and coking coal dust with poor wettability as research objects，the basic characteristics of micro⁃nano bubble water and its adsorption and wettability to dust are studied through experiments. The spray dust suppression efficiency of mi⁃ cro⁃nano bubble water and tap water is compared based on the self-designed experimental platform for spray dust sup⁃ pression. The experimental results show that micro bubbles can exist in water for a short time while nano bubbles can exist in water for a long time. The Zeta potential of the micro⁃nano bubble water is higher than that of the ultrapure wa⁃ ter，and dust can effectively adhere to the charged bubbles. The surface tension of the micro⁃nano bubble water is 5.5 mN / m lower than that of tap water，and with the gradual rupture of micro bubbles，the surface tension of the mi⁃ cro⁃nano bubble water increases slowly. The contact angle to coking coal particles of the micro⁃nano bubble water is 4.58° smaller than that of tap water，and micro⁃nano bubbles can enhance the wettability of water to coking coal parti⁃ cles. With the increase of contact time，the contact angle of micro⁃nano bubble water and tap water to coking coal par⁃ ticles decreases continuously，and the reduction rate of micro⁃nano bubble water is larger. micro⁃nano bubble water is an unsteady system，and is easier to evaporate than tap water. Compared with tap water，micro⁃nano bubble water can increase the concentration of negative oxygen ions around the spray. As the water supply pressure of the X⁃shaped swirl pressure nozzle gradually increases，the spray droplet size of micro⁃nano bubble water and tap water decreases. At the same nozzle water supply pressure，the spray particle size of micro⁃nano bubble water is smaller than that of tap water，but not differs significantly. With the increase of water supply pressure，the dust suppression efficiency of nozzle increases continuously，and the micro⁃nano bubble water shows a higher dust suppression efficiency than that of tap water. Micro⁃nano bubbles contribute to the wetting and condensation of dust，and are conducive to the capture of re⁃ spirable dust.