Study On The Adsorption Mechanism Of Composite Foaming Agent On Coal Dust Surface

Coal dust, one of the major hazards in coal mines, not only leads to pneumoconiosis, but also results in serious dust explosion, brings huge disasters and economic losses for miners, enterprises and the society. At present, coal dust control technology such as ventilation, dust collector and water spraying are common used in coal mines, however, these technologies are physical methods which has a low efficiency and poor adaptability. Foam dust control technology has made great breakthroughs since proposed, but the research is mainly confined to the foam generator and foaming process conditions. Therefore, the study on composite foaming agent and it’s mechanism adsorption on the surface of coal dust is very important.In this thesis, the basic physical and chemical characteristics of coal dust are analyzed through industrial analysis, FTIR spectra analysis and laser particle size analysis. The author choose SDS and CAB-35as foaming agent, OP-10as wetting agent, PVA as foam stability agent by the single factor optimization experiment. The four kinds of surfactants are composited by uniform design and the results are analysised by stepwise regression. The optimal scheme is:SDS adding amount is0.32%, the CAB-35adding amount is0.40%, the OP-10adding amount is0.29%, the PVA adding amount is0.01%.The adsorption characteristics of single-component and multi-component surfactants on the surface of coal dust are studied. The results show that, the adsorption type of CAB-35and composite foaming agent, belong to LS double platform type, which is a multilayer adsorption. The adsorption isotherm of SDS, OP-10and PVA, belong to L-type, follow the Langmuir isotherm of monolayer adsorption. The adsorption mechanism shows that, SDS and OP-10are adsorbed on the surface of coal dust by dispersion force, which is by hydrogen bonding for PVA, while CAB-35is by the strong electrostatic attraction, and each single-component adsorption ability is CAB-35>PVA> OP-10>SDS.The adsorption of composite foaming agent on coal dust surface present significant synergistic effect at the same equilibrium concentration, among them CAB-35presents active adsorption, while SDS, OP-10and PVA present passive adsorption.This thesis also study the factors which affect the adsorption capacity on coal dust surface. Experiments show that, coal dust particle size and the solution temperature are negative correlation with adsorption capacity, and with the increase of both NaCl and silicon dioxide content, adsorption capacity is also increasing. However, the effection of pH on adsorption capacity of coal dust is relatively complex, when pH<7, adsorption capacity decreased with the increase of pH, when pH>7, it’s just the opposite. Using the moisture, ash, volatile and fixed carbon as variables to establish a multivariate linear relationship between the coal industrial analysis and adsorption capacity through the stepwise regression method of DPS.