| As a country with abundant coal resources,with the large-scale industrial exploitation,the problem of mine fires is becoming more and more serious.The occurrence of fire will not only cause waste of resources,but also bring a huge threat for coal mine production safety.At present,the fire prevention technology of coal mine goaf is mainly to inject liquid or inert gas into the fire area.The development of new materials and the improvement of fire prevention technology are the main research priorities.Combining the advantages of cold aerosol fire extinguishing technology and inhibitor fire prevention technology,this paper attempts to provide a new way to prevent coal spontaneous combustion in coal mine goaf.That is,the two mutually reactable inhibitor solutions are wetted by atomization diffusion to infiltrate the coal sample,and form a precipitate on the surface,while achieving physical and chemical resistance.Experiment selected Yunnan Zhaotong brown coal as research object.Aerosol resisting experiments were carried out on coal samples by aerosol resistance device,and the effects of different cold aerosol inhibitors on coal samples were compared and analyzed according to the results of Programmed heating test,thermogravimetry and Fourier infrared spectroscopy.The following experimental results are obtained:(1)The combination of the four inhibitors selected in the paper can effectively increase the solid residue on the surface of the coal sample after the ultrasonic atomization treatment diffusion reaction.The weight gain of precipitation products is obvious,which can account for 1%-5% of the coal sample quality.This part of solid residue can cover or enter the coal sample cracks,hinder the contact between coal and oxygen,and achieve physical retardation effect.(2)The Programmed heating test experiment was carried out on raw coal and cold aerosol.Then the consumption and gas production of four groups of treated coal samples and raw coal are compared and analyzed.The experiment found that the raw coal and treated coal samples maintained similar oxidation characteristics throughout the heating period.In the slow oxidation stage,the oxygen consumption and CO production of treated coal samples are smaller than that of raw coal but the difference is small.The oxygen consumption and CO production of treated coal decreased significantly after entering the rapid oxidation stage after 100℃.Moreover,the inflection point temperature of gas changes also lags behind to varying degrees,which indicates that the cold aerosol inhibitor can effectively inhibit the oxidation reaction of coal samples at low temperature.(3)The thermal characteristics of the coal sample during the temperature rising oxidation process were analyzed by TG/DSC technique.It is found that the effect of cold aerosol on the coal sample is mainly after the coal sample enters the rapid decomposition stage compared with the raw coal.By comparing the change of characteristic temperature points of each sample,it is found that the maximum weight loss rate and maximum heat release rate of treated coal samples are all shifted to about 100℃ in high temperature stage.And in the DSC curve,it can be seen that the area of the exothermic peak of the treated coal sample is reduced,indicating that the cold aerosol inhibitor improves the thermal stability of the coal sample in the high temperature stage.(4)Fourier infrared spectroscopy showed that the hydroxyl groups in the functional group of Yunnan Zhaotong brown coal accounted for a large proportion,in addition to a large number of alcohol phenol ethers and carboxyl oxygencontaining functional groups.By analyzing the infrared spectrum of different samples,it can be seen that the chemical inhibition effect of cold aerosol inhibitor on coal samples is mainly reflected in-OH,aliphatic hydrocarbons and oxygencontaining functional groups such as carbonyl and carboxyl groups.The chloride salt composition of cold aerosol inhibitor has a strong consumption ability to the above functional groups,thus reducing the activity of oxidation reaction between coal and oxygen. |
