| Coking coal has the characteristics of large dust production and strong hydrophobicity in the process of mining.Coking coal dust not only affects the physical and mental health of coal miners,but also brings great hidden dangers to coal mine safety production.Spray dust control technology is mainly used in coal mines in China.Although some achievements have been made,the concentration of coal dust in most mines is still high.In recent years,chemical dust suppression has been used to reduce dust concentration in China,but the lack of systematic understanding of the micro-mechanism of chemical dust suppression has limited the development of chemical dust suppression.In order to prepare an efficient chemical dust suppressant for coking coal dust,the basic characteristics of coking coal are analyzed from the microscopic point of view.The effects of surface tension,contact angle and capillary reverse osmosis on the wettability of coking coal are studied by means of surface tension,surfactant composition,surfactant and hygroscopic inorganic salt combination,and the optimized surfactant is also studied.Three factors and four levels orthogonal test were carried out with inorganic salt to obtain the formula of dust suppressant for coking coal dust.Finally,the new formula is combined with spray dust control technology to discuss the relationship between chemical dust suppressant and dust control effect.The main conclusions are as follows:(1)the moisture and ash content of coking coal is higher than that of coking coal,and the volatilization is lower than that of coking coal.The contact angle between Wan Feng coking coal and Liupanshui coking coal is close to 90 degrees,which belongs to hydrophobic coal.The contact angle of coke coal is small,and the moisture absorption of reverse osmosis is large.The wettability of coke coal is better than that of coke.Coking coal has better water retention than coking coal.(2)With the increase of surfactant concentration,the surface tension of the solution decreases at first,and reaches the critical micelle concentration(CMC),then the surface tension tends to be flat.Different surfactants have different wetting effects on coking coal.The wettability of the same surfactant to coking coal is proportional to its concentration.The higher the concentration,the smaller the contact angle,the larger the reverse osmosis moisture absorption,the better the wettability.When most surfactants were mixed,the moisture absorption and wettability increased obviously,and the wetting effect was greater than that of monomer solution.The combination of anion and non-ion has the greatest moisture absorption and the best wetting effect.The wetting effect of cations compounded with otherions is not good.There is no obvious relationship between surface tension and reverse osmosis moisture absorption.The contact angle and surface tension of the mixed solution are not completely positively correlated.(3)The complex solution of inorganic salts and surfactants reduced the surface tension of the solution slightly,but the moisture absorption increased obviously in reverse osmosis experiment.For anionic surfactants,cations in inorganic salts play a major role in reducing surface tension;for nonionic surfactants,salt dissolution and salting out of hydrophobic groups of surfactants play a major role in reducing surface tension.The higher the valence of positive ions in inorganic salts,the greater the ability of wetting coal dust.Water retention of inorganic salts is related to their own charged ions and wettability of coal dust.Three schemes of dust suppressants were optimized by orthogonal test.(4)Spray dust suppression system was used to test three formulations under different water supply pressures,and water was used as control.The higher the water supply pressure was,the better the dust reduction effect was.By reducing the surface tension of the solution,the chemical dust suppressant makes the solution easier to break into smaller droplets,and increases the probability of coal dust capture. |
PDF Full Text Request