Study On The Characteristics Of Layered Double Hydroxides Inhibitor For Coal Oxidation

Layered double hydroxides(LDHs)is a kind of halogen and phosphorus free multifunctional inorganic material has the advantages of high efficiency,environmental protection,safety,smoke suppression,thermal decomposition and release of water vapor and carbon dioxide and other advantages,can be used as a new type of coal spontaneous combustion inhibitor.However,at present,the study of layered double hydroxide inhibitor is still in its infancy.In this paper,a new type of layered double hydroxide inhibitor was synthesized,and the characteristics and mechanism of the spontaneous combustion of coal with different metamorphic degree were studied.The in-situ preparation of a ZnMgAl-CO3-LDHs layered double hydroxide inhibitor co-precipitation samples were analyzed by means of thermo-gravimetric test structure and infrared spectra,obtained the inhibitor oxidative decomposition and release a lot of heat,water vapor and carbon dioxide gas two.The results show that the layered double hydroxide has the characteristics of delaying the natural oxidation of coal and reducing the oxygen concentration of coal surface.Four kinds of coal samples with different metamorphic degree(SF-coal,XJ-coal and YQ-coal)were selected and mixed with the prepared inhibitor.Thermo-gravimetric analysis and differential scanning calorimetry(TG/DSC-FTIR)were used to study the coal samples with different ratios of the layered double hydroxide inhibitor.Coal spontaneous combustion characteristic temperature TG curve shows the critical temperature,dry temperature,ignition temperature,adding inhibitor of coal sample was higher than that of coal,when the inhibitor dosage of 20%increased the maximum amount of All kinds of DSC curves are exothermic peaks.The exothermic peak area of coal sample with inhibitor is obviously less than that of coal sample.The results show that the ZnMgAl-CO3-LDHs layered double hydroxide inhibitor can be used to suppress the spontaneous combustion of coal in the process of multistage heat absorption.The infrared spectrum analysis showed that the amount of CO and CO2 released by the oxidation of coal samples was obviously reduced,and the more the amount of the inhibitor was added,the smaller the amount of gas produced.According to the results of thermo-gravimetric analysis,the activation energy of the oxidation process of the raw coal and the coal sample was studied.Therefore,the ZnMgAl-CO3-LDHs layered double hydroxide inhibitor has a good effect on the coal of different metamorphic degree,especially for long flame coal and non stick coal.The activation energy of the blocked coal sample increases,which indicates that the layered double hydroxide inhibitor may change the type or process of coal oxidation reaction,and thus play a role in chemical resistance.