Experimental Study On CO₂ Adsorption Characteristics Of Anthracite In Yangmei Minmetals

As the greenhouse effect of CO₂ leads to climate change,injecting CO₂ into the goaf is beneficial to prevent spontaneous combustion of coal,and at the same time achieve CO₂ storage to reduce greenhouse gas emissions,which has the dual benefits of safety and the environment.The adsorption of coal to gas is directly related to coal spontaneous combustion,gas storage,and CBM production.Gas composition,water content,particle size and pore structure are important factors that affect the adsorption of CO₂ by coal.Combined with the experimental test,the experimental study on the influence factors of coal on CO₂ adsorption was carried out.Through the adsorption/desorption experiment of coal to single component（N₂,CO₂,O₂）gas,it is concluded that the adsorption amount of coal sample to single gas has the law of CO₂>O₂>N₂at room temperature,and the adsorption amount of CO₂ is O₂,N₂ respectively 18 times and 25times the adsorption capacity.Coal samples from 8419 working face have desorption hysteresis for N₂,CO₂ and O₂ single-component gases.The BET model is more suitable to describe the isothermal adsorption/desorption characteristics of coal for N₂,CO₂ and O₂ single-component gases.Through experiments on the adsorption characteristics of coal samples on multi-component mixed gases（CO₂/Ar,CO₂/air）under normal temperature and pressure,it is concluded that the coal samples with low CO₂ concentration reach the adsorption equilibrium in about 10 hours,and the coal samples with high CO₂ concentration reach adsorption equilibrium in about 12 hours.Under CO₂/Ar ratio atmosphere and CO₂/air ratio atmosphere,the adsorption amount of CO₂ by coal samples increased exponentially with the increase of CO₂ concentration.Under the same CO₂volume fraction,the adsorption amount of CO₂ by coal samples in CO₂/Ar atmosphere is greater than that in CO₂/air,and the larger the CO₂ volume fraction,the greater the difference between the two,because there is O₂ in the air.and N₂,which will compete with CO₂ for adsorption.The components of the multi-component mixed gas interact with each other.The adsorption amounts of CO₂,N₂ and O₂ are as follows:CO₂>O₂>N₂,CO₂ occupies more adsorption sites,and CO₂hinders the coal sample from adsorbing O₂,which helps prevent coal Spontaneous combustion.Carrying out the test experiment of the adsorption capacity of coal samples with different moisture contents on CO₂,it is concluded that the adsorption capacity of coal samples with different moisture contents increases exponentially with the increase of time,and the adsorption reaches equilibrium after 12h.The adsorption capacity of coal samples to CO₂ decreases exponentially with the increase of water content,and the decreasing rate is fast first and then slow.Not much.The presence of moisture will inhibit the adsorption of coal to gas,and the adsorption of CO₂ by the dry coal sample is 1.23 times that of the coal sample with a moisture content of13.4%.By carrying out CO₂ adsorption experiments on coal samples with different particle sizes,it was found that the adsorption capacity of coal samples increased exponentially with the adsorption time,and the adsorption equilibrium was reached in 12h.The CO₂ adsorption capacity of coal samples decreases exponentially with the increase of particle size.Under the conditions of normal temperature and pressure and particle size of 60-80 mesh,the adsorption of CO₂ on the five dry coal samples all reached the saturation state in 12h.The pore structure of coal samples was tested by low temperature CO₂ adsorption method,low temperature N₂ adsorption method and mercury intrusion method,and the pore structure of coal samples was jointly characterized.The adsorption capacity of coal samples was fitted with the corresponding pore volume and pore specific surface area data of each stage,and it was obtained that the adsorption capacity of coal samples to CO₂ was related to the total pore volume,micropore volume,total pore specific surface area,micropore The increase of the specific surface area increases exponentially,and with the increase of the macropore pore volume,it shows an exponential decrease.The research in this paper provides a theoretical basis for the use of CO₂ to prevent spontaneous combustion in goafs,predicting the storage of CO₂ in gobs and realizing CO₂emission reduction in coal fire disasters and low-carbon environmental protection.The paper has 36 figures,25tables,and 92 references.