Experimental study of deformation rules during the process of gas adsorption and desorption in briquette coal

Abstract

Gas is one of the most important factors which causes coal and gas outburst and can influence the mechanical characteristics of coal. Coal itself is a kind of elastic carbonaceous material which can swell and shrink under the influence of gas adsorption and desorption. Solid deformations influence the porosity of coal which also changes its adsorption and desorption capability. Gas pressure due to gas adsorption in porous materials is the cause of elastic deformation of coal, which can be assessed by direct experimental measurements. In this paper, briquette coal samples are made with different sizes of coal particles and the deformations are tested during the process of gas adsorption and desorption in samples under different gas pressures. The results show that coal swells during gas adsorption and shrinks during desorption. Deformation of different coal samples under different gas pressures is variable. It is further observed that deformation of coal is proportional to gas pressure and particle size. Also, deformation is not recoverable and residual deformation develops. The relationship between residual deformation and gas pressure is derived. This study helps to reveal the damage mechanism of pore gas in cola mass.

Keywords:

• pore gas
• adsorption–desorption
• swelling expansion
• residual deformation

Acknowledgements

The authors gratefully acknowledge funding by the China National Key Basic Research Development Project Program (2011CB201202-2), National Natural Science Foundation Project (51374216, 50874110), the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China (111053) and the Fundamental Research Funds for the Central Universities (2009kz03).