Research And Appliciation Of Inhibiting Coal Spontaneous Combustion Technology By Liquid CO₂

Most of the coal seam has short spontaneous combustion periods.To prevent fire disaster critically damages the mining sustainable development and the miner's lives are safe.Liquid CO2 treatment of coal fire disaster which has large range of cooling,inerting,and well anti-explosive effect.This paper is based on the characteristics of liquid CO2 phase transition.Using high-temperature loose coal body cooling experiment device,simultaneous thermogravimetric?TG?analysis method,and electron microscope scanning were adopted to invest the cooling law of liquid CO2.Using cooling experiment instrument to invest the variables of pressure injection and injection flow.The entire process of temperature changes and cooling area characteristics were compared with the cooling rate of liquid nitrogen.The findings indicate that the cooling area and amplitude increase with the increase of bore diameter and flow rate.The phase change process occurs quickly after pressure injection,and phase change produced the significant cooling effect.Because of the macromolecule characteristics of CO2,it will stay in the high-temperature loose coal for a longer period of time for continuous cooling,and the effect of cooling and re-ignition prevention is better than liquid nitrogen.Then,employing TG analysis method to compare the thermokinetic parameters between raw coal samples and coal treated with liquid CO2 samples.The results show that coal characteristic temperature increases with higher heating rates.From the results of thermal analysis and electron microscopy scanning experiments,it is shown that coal samples treated with liquid CO2 can effectively retard coal-oxygen recombination rates compared to raw coal samples.Using liquid CO2 to treat coal also decreased the characteristic temperature of coal samples.The apparent activation energy of coal treated with liquid CO2 samples are higher than that of raw coal samples,it expresses that the reignite prevention works.To the end,fire prevention and extinguishing technology by liquid CO2 was used to control and successfully uncover 110215 surface fire in a coal mine.The results of this study verify that liquid CO₂ has better cooling effect and inerting effect than Nitrogen.