Experimental Research On The Thermal Effect And Kinetics Of Imidazolium Ionic Liquids For Inhibiting Coal Spontaneous Combustion

Coal spontaneous combustion(CSC)is a global concern,because it damages the environment,the economy,social development,and human health.Inhibitory technology has achieved good results in prevention and control of CSC.Ionic liquids(ILs)are new types of green solvents that inhibit the active functional groups in the molecular structure in coal.In this paper,the purpose of the application of ILs inhibit CSC in fire-fighting field.The main research imidazole ILs inhibit the CSC process,thermogravimetry,enthalpy,thermodynamic parameters,thermophysical parameters,oxygen consumption rate,inhibiting effect,et.It provided the basis for the research and application of ILs inhibitor.Using the thermogravimetry,differential heat,and thermal properties testing techniques to study the characteristics of CSC characteristics of three different coal ranks,and to understand the characteristics of CSC stages.Then,investigate the thermal effect and kinetic differences of imidazolium ILs([EMIM][BF4],[BMIM][BF4],[BMIM][NO3],[BMIM][I])on the bituminous CSC.The results showed that the ILs had a significant weakening effect on the mass loss process of CSC,and the effect of different ILs were different.Regarding the anion[BF4]-,[BMIM]+ produced a stronger effect than did[EMIM]+;Inhibitory effect on bituminous coal of different anions with the cation[BMIM]?,the effect of[NO3]-is stronger than that of[BF4]-and[I]-.The results of differential thermal analysis show that the peak temperature of[BMIM][BF4]treated coal increased by 28?.By using the method of kinetics,the results show that the Ea of[BMIM][BF4]treated coal is higher than that of other coal samples,its inhibition is better.The thermophysical properties of the samples indicated that the ILs all change the thermophysical properties.At the same temperature,the thermal diffusivities and thermal conductivities of the ILs treated coal are lower and the specific heat capacity is higher than the raw coal.Two kinds of ILs([BM]M][BF4],[BMIM][I])as inhibitors in different mass ratios(0.5,2,5,10%)were added to the bituminous coal sample.By comparing TG-DTG,with the increase of the addition ratio,a small mass loss occurred.The results of DSC analysis illustrated that the peak temperature was 0%<0.5%<2%<10%<5%.The thermophysical properties showed that the thermal diffusivity gradually decreases with the increase of the addition,the specific heat capacity increases gradually,and the thermal conductivity decreases.The same addition ratio,the same temperature,by TG-DSC curve analysis 5%[BMIM][BF4]on the coal spontaneous combustion more obvious.Lastly,lignite and anthracite treated by 5%[BMIM][BF4]was analyzed.TG-DSC results indicated that[BMIM][BF4]treated lignite,retarded the maximum rate of mass loss of and the maximum exothermic peak was about 45?C,and for anthracite was 10 ?.It was concluded that 5%[BMIM][BF4]can inhibit the CSC in different coal rank,and the effect is different.The result of thermophysical test showed that the treatment of lignite and anthracite with 5%[BMIM][BF4]was the same result as that of bituminous coal.The results of temperature programmed experiments showed that the oxygen consumption rate of coal samples increased slowly with the increase of temperature and rapidly increased after T1.Moreover,T1 tended to increase with coal rank increased.As the temperature increased,the oxygen consumption rate of 5%[BMIM][BF4]-tc was less than raw coal,thus 5%[BMIM][BF4]could inhibit CSC.The calculated Earepresented that the value of 5%[BMIM][BF4]-tc the corresponding phase all increased than raw coal.[BMIM][BF4]increased the degrees threshold that ordinary molecules into activated.By calculating inhibiting effect of each sample,the inhibiting effect of[BMIM][BF4]-tc were all above zero.Therefore,it was universally applicable that the inhibit CSC for different rank.