Analysis of internal pore structure of coal by micro-computed tomography and mercury injection

Abstract

Micro-computed tomography (CT) technology and mercury injection were applied to study the internal pore structure of coal samples from the Gaojia kiln (Datong coal field) and Fulong bay coal mine. The results show that significant differences exist between different samples. The pore connectivity study shows that the number of maximum connective pore groups in coal samples 1, 2, and 3 is small. They are dispersed and confined to a small area with small permeability probability and low permeability. The maximum connective pore group percentage of coal sample 4 is higher, the porosity is larger, the permeability probability is higher and the permeability is better. By comparing the results obtained from micro-computed tomography and mercury injection studies, it can be concluded that the pore structure of coal consists mainly of open seepage pores. The volume of coal sample 4 accounted for the largest percentage of the total pore volume (up to 90%), whereas that of the closed pores is lower. Large amounts of methane gas can be extracted by predrilling during coal mining in Fulong bay and Gaojia kiln. This extraction may reduce the occurrence of safety accidents in coal mines. [Received: May 2, 2014; Accepted: December 3, 2014]