Release Laws And Mechanism Of CO Produced By Coal Structure Destruction And Modification Method Of The Index For Predicting Coal Spontaneous Combustion

Carbon monoxide(CO)is one of the gaseous productions of coal spontaneous combustion,and it is used as index gas to forecast and predict coal spontaneous combustion in most coal mines of China currently.However,many observation results show that even though coal spontaneous combustion does not occurred,CO concentration still increase abnormally.Therefore,correctly and effectively distinguishing the sources of CO in coal mine and make clear the release laws of it has a significant influence on the forecast and prediction accurancy of coal spontaneous combustion.In this paper,laboratory coal crushing experiments were conducted by a self-designed experimental system to investigate the release law of S-CO(one source of CO which is decomposed from the mechanical disruption of coal structure)and temperature rise,taking jet coal from Inner Mongolia of China as samples.Coal lump mass and motor rotational speed was two main parameters to be considered.Results show that: the moment S-CO concentration rise and temperature rise appeard was little influenced by coal lump mass and motor rotational speed during coal crushing process.But when motor rotational speed changed from 15000r/min to 10000r/min,the moment S-CO concentration rise and temperature rise appeared had an obvious delay,about 50 s and 70 s separately.Furthermore,the value of average S-CO production rate and maximum S-CO concentration increased with the increase of coal lump mass and motor rotational speed.Temperature rise obviously effected by motor rotational speed,but unobviously effected by coal lump mass.The changes of S-CO concentration can be divided into 3 periods,no S-CO production period,S-CO linearly increase period and S-CO exponentially increase period.The coal samples were further analyzed by fourier transform infrared spectroscopy(FTIR)method to explore S-CO production mechanism.After analyzing the changes situation of functional groups and chemical bonds on the surface of coal struction during the crushing process,it was indicated that S-CO was produced by two ways:S-CO produced from the destruction of carboxylic acid,ether,peroxide and other chemical structure contain oxygen.S-CO produced from the decomposition ofoxygen-containing functional groups like carboxyl,linkage,peroxide bond,hydroxyl,etc.dut to the increase of internal energy which was caused by the motor power.The experimental data were further analyzed to calculate the absolute production amount and average production rate of S-CO,and the relation between S-CO absolute production amount and coal lump mass was conducted.Less square method(LSM)was used to explore the relationship between average S-CO production rate and temperature rise.R2 was 0.8633 which means these two parameters correlated well for all samples.What’s more,the CO concentration calculation model of mining face was established.The calculation method of S-CO concentration during mining process was conducted.And the CO concentration and CO concentration variation rate was modified by the results and relations above.