Study On The Effect Of Citric Acid On Spontaneous Combustion Characteristics Of Coal

Coal spontaneous combustion is an important predisposing factor for coal mine fire accidents.It will not only cause a large loss of coal resources and air pollution,but may also cause other mine accidents,posing a threat to the life safety of underground personnel.With the continuous research of coal self-ignition resistance technology,various inhibitors have become an important means of coal mine fire prevention,but the inhibitors also have the defects of low resistance during use.The fundamental reason is the influence of inhibitors.There are few researches on the mechanism of spontaneous combustion of coal.Therefore,the research on new high-efficiency inhibitor and resistance mechanism is important for the prevention and control of coal spontaneous combustion.Based on the study of the effect of metal ions on coal spontaneous combustion,the metal ion chelating agent citric acid was proposed as a coal spontaneous combustion inhibitor to resist the coal sample,and its flame retardant properties were studied.Three kinds of coal samples from Chifeng and Daliuta Dafosi were selected in the experiment.The effects of macroscopic properties,reactive functional group content and pore structure change from the products of coal oxidation process,such as product temperature,cross-point temperature and activation energy,were studied.And get the following research results:Through the temperature-programmed oxidation experiment,it is found that the concentration of CO and CO₂ in the raw coal and the resistive coal sample increases gradually with the increase of the experimental temperature,but the increase trend of the coal sample after the inhibition is gentler than that of the original coal;the O₂concentration gradually decreases.The oxygen consumption rate of the coal sample after the inhibition is lower than that of the original coal;the temperature of the intersection of the three coal samples increased by 9 to 12?after the resistance treatment,and the time was also delayed by 3 to 50 minutes.Based on the change of oxygen consumption,the activation energy of coal oxidation process before and after resisting was calculated by using the Arrhenius formula.It was found that the activation energy of the three coal samples after different resistance treatments increased to different degrees.High,in which the Chifeng coal sample increased by7.1 kJ·mol^-1.Through the thermal analysis experiment,it is found that the characteristic point temperature of the three coal samples after the resistive treatment is shifted back compared with the original coal.The weight loss rate of the raw coal at the same temperature point is greater than that of the resistive coal sample,and the reaction of the raw coal when the coal sample enters the rapid combustion stage.The enthalpy change is greater than the resistance coal sample.The parameters related to the pore structure characteristics of each coal sample were determined by low temperature nitrogen adsorption method.It was found that the specific surface area of the three coal samples decreased after treatment,and the highest reduction rate reached 57.4%.The pore size and pores of the coal sample after the inhibition The volume is also smaller than the original coal.The parameters related to the pore structure of each coal sample were determined by low temperature nitrogen adsorption method.It was found that the specific surface area of the three coal samples decreased after treatment,and the highest reduction rate reached 57.4%.The pore size and pore volume are also reduced compared to the raw coal.Through the analysis of the above experimental results,it was found that the use of citric acid as a retarding agent has a good effect of suppressing spontaneous combustion of coal.