Distribution Of Pahs In Coal Gangue And Its Precipitation Characteristics During Spontaneous Combustion

Polycyclic aromatic hydrocarbons?PAHs?are organic pollutants and these widely founded in the environment and are carcinogenic,toxic,teratogenic and mutagenic.In order to research the distribution of PAHs in different ranks of coal gangue,and the influence of different temperature and different air velocity on the distribution of PAHs in coal gangue and the precipitation characteristics during spontaneous combustion,in this paper,PAHs in three samples were analyzed by Soxhlet extraction and high performance liquid chromatography?HPLC?,respectively:?1?Different ranks of coal gangue;?2?Xishan Duerping Coal Mine in Taiyuan,Shanxi Low-temperature spontaneous combustion of coal gangue and its emitted gas;?3?laboratory simulation of coal gangue spontaneous combustion.Through analysis,the following conclusions are drawn:?1?For the different ranks of coal gangue of vitrinite reflectance of1.21-3.30:the proportion of high molecular weight polycyclic aromatic hydrocarbons?HPAHs?increases first and then decreases with the increase of metamorphism;Ant/?Ant+Phe?ranges from 0.00 to 0.03;Flua/?Flua+Pyr?ranges from 0.10 to 1.00;BaA/?BaA+Chr?ranges from0.04 to 1.00;the value of Total index ranges from 1.03 to 7.50.?2?In the low-temperature spontaneous combustion process of coal gangue,with the decrease of spontaneous combustion temperature,the trend of?₁₆PAHs concentration in emitted gas increases,and the trend of?₁₆PAHs concentration in coal gangue decreases;the lower the spontaneous combustion temperature,the higher the toxic equivalent and the concentration of?₁₀HPAHs in coal gangue and its emitted gas.The value of Total index in in-situ low-temperature spontaneous combustion coal gangue is from 21.00 to 22.43;the value of Total index in its emitted gas is from 20.10 to 21.83.?3?The precipitation characteristics of PAHs in the laboratory simulated spontaneous combustion of coal gangue at different air velocity are as follows:?a?Under low temperature and low air velocity,PAHs in coal gangue are the source of rock formation;under low temperature and high air velocity,PAHs in coal gangue have both rock source and combustion source.?b?When the combustion temperature is450-850?:PAHs in coal gangue have both rock source and Pyrolysis source.?c?When the combustion temperature from 150?to 950?,the mean of Total index ranges from 1.73 to 8.30.