Gas Desorption And Diffusion Law Of Coal Particles After Acid Soaking

Coal seam methane is the major killer of the safety production of coal mine.At the same time,coal seam methane has application value as a clean efficient energy.Especially for the coal gas desorption and diffusion is one of the important issues of coal mine safety production.The coal particle samples were treated with the infiltration process by distilled water,Fenton reagent,hydrochloric acid and acetic acid respectively.Then,the samples gas desorption law under the same adsorption equilibrium pressure and temperature were studied by the self developed high pressure and temperature-change gas adsorption-desorption experiment system.The result showed that,both the cumulative desorption amount and desorption rate were decreased after being infiltrated;the gas diffusion coefficient D calculated by the Yang' method increased after being infiltrated by acid and water.The results suggested that the acid infiltration process inhibited the adsorption capacity while promoted the gas desorption capacity.The pore distribution of coal samples before and after acid and water infiltration were determined by the low field nuclear magnetic resonance instrument.The result showed that the pore distribution and pore volume of coal samples infiltrated by distilled water,hydrochloric acid and Fenton reagent did not change obviously,while the pore volume change of coal sample after being infiltrated in acetic acid was relatively obvious;The gas desorption-diffusion characteristics and pore distribution characteristics of samples showed inconsistent tendency before and after infiltration.The composition content of the surface functional groups were determined by FT-IR before and after acid infiltration.And the factors affected the desorption and diffusion characteristics were discussed.The results showed that the desorption and diffusion characteristics of particle coal gas were affected by the pore characteristics,particle surface polarity and surface containing oxygen functional groups composition.The FT-IR test results proved that the coal sample was soaked by water,Fenton reagent,hydrochloric acid and acetic acid,the surface acidic groups(phenol,alcohol hydroxyl and carboxyl)all had the trend of increasing while the acidic groups reduce the adsorption ability of coal to methane and inhibit the adsorption of coal to methane.