Study On Synergistic Effect Of Surfactant Compounding On Wettability Of Coal Dust

A large amount of coal dust will be produced during the production of coal mines.It will not only cause incurable deaths of pneumoconiosis from miners,but also lead to explosion accidents in the mines,causing major personal injuries and huge economic losses.Dust suppression by chemical agent is a kind of active and effective dust control method in coal mine.It can improve the hydrophilicity and wettability of coal dust particles by adding surfactant into the water for dust control.In order to study the synergistic effect of surfactant compounding on improving wettability of coal dust and dust suppression effect,six kinds of coal samples and 15 kinds of surfactants including lignite,long flame coal,non-caking coal,gas coal,coking coal and anthracite,were selected from typical mining areas in China.Firstly,the industrial composition,element content,chemical structure,micro morphology,pore structure characteristic parameters and contact angle of water on the surface of coal dust were measured to explore the main influencing factors of coal dust wettability.Then the single component of the compound surfactant is optimized,a compound surfactant was produced by mixing two surfactants in equal volume,the critical micelle concentration(CMC)of surfactants was selected as the concentration of the compound solution.The surface tension of surfactant,the contact angle of surfactant on the coal dust surface and the wetting speed of coal dust under the action of surfactant were measured,using them as indicators to measure the effect of compound surfactants on the wettability of coal dust.The adsorption-wetting characteristics of monomer and compound surfactant on the surface of coal dust was discussed from the microcosmic.Finally,a self-made spray dust simulation experimental platform and coal mine spray dust experiment were conducted to evaluate the wetting effect of compound surfactants on 6 kinds of coal dust with different metamorphic degrees.The results show that in the physical and chemical properties of coal dust,the average pore size is the most important factor affecting the wettability of coal dust surface,and the contact angle decreases linearly with the increase of pore size(R2=0.96).In addition,the wettability of six kinds of coal dust shows a high-low-high trend with the increase of metamorphic degree.The wettability of lignite is the strongest,and the wettability of coking coal is the weakest.The anionic-nonionic compound surfactant has the most significant effect on improving the wettability of coal dust.The surface tension of the anionic-nonionic compound surfactant is lower than that of the monomers,especially the surface tension of FMES-CDEA is 29.23mN/m,which is 20.18%and 13.42%lower than that of FMES and CDEA.The contact angle of the anionic-nonionic solution on any coal piece is 14.04%?63.31%lower than that of the single component.The wetting speed of coal dust in the anionic-nonionic compound surfactant is 27.28%?28 times faster than that in the single componentThe adsorption amount and form of surfactant on the coal dust surface are important factors affecting the wettability of coal dust.The larger the adsorption amount of surfactant on the surface of coal dust,the easier the coal dust will be wetted,the single adsorption form of anionic and nonionic surfactant on the surface of coal dust is more conducive to enhance the wettability of coal dust.The concentration of anionic-nonionic compound solution is lower than that of anionic-anionic compound solution when it reaches adsorption saturation on the surface of coal dust.The anionic-nonionic compound solution can significantly increase the adsorption amount on the surface of coal dust.The hydrophobic groups of anionic and nonionic surfactants adsorbed to the surface of coal dust in the form of spaced surroundings(the nonionic surfactant molecules are inserted into the anionic micelle)were easier to wet coal dust.In the spray simulation experiment,the dust suppression efficiency of anionic-nonionic conpound solution as an additive for spray dust reduction is better than that of anionic-anionic conpound solution.The dust suppression efficiency of gas coal in 0.025 wt%FMES and 0.025 wt%CDEA conpound solution was the highest,which was 78.4%.Lignite,long flame coal,non-caking coal,coking coal,and anthracite had the highest dust suppression efficiency in the conpound solution of 0.025 wt%AES and 0.025 wt%CDEA,which were 91.53%,88.24%,85.7%,73.25%,and 80.57%,respectively.Field test showed that for non-caking coal,the dust suppression efficiency was the highest when 0.025wt%AES and 0.025wt%CDEA was added.The dust suppression efficiency of total dust and respirable dust was 88.32%and 86.12%respectively,which was 40.76%and 46.06%higher than that of untreated water,which could effectively reduce the dust concentration,especially respirable dust.At the same time,the dust suppression efficiency of the anionic-nonionic compound solution as an additive for spray dust suppression is better than that of anionic-anionic solution,which is consistent with the conclusion obtained from the spray simulation experiment.In a word,the anionic-nonionic compound surfactant showed a significant synergistic effect on improving coal dust wettability.The research results provide a theoretical basis for the dust suppression with surfactant solution in coal mines,the adaptive characteristics of different coal dust and surfactant solution are proposed,it provides a reference for selecting and preparing surfactant solution as a spray dust additive to improve the suppression efficiency.Figure[106]table[22]reference[111]...