Effects of composition changes of coal treated with hydrochloric acid on pore structure and fractal characteristics

摘要

In order to investigate the influence of coal compositions on the pore structure, low temperature gas adsorption (LTGA) method was used to analyze the pore evolution of coal samples treated with hydrochloric acid. The results demonstrate that hydrochloric acid treatment significantly reduced the content of minerals and volatile matter in coal, which could increase the porosity and the pore connectivity of coal. The removal of volatile matter has an obvious reaming effect on supermicropores, but ultramicropores remained unchanged. The role of minerals in pores of different pore widths is different, which are the fillers in macropores, the skeletons of some large mesopores and the blockage in some small mesopores. With the decrease of minerals, the macropore volume increased, and the large mesopore volume first decreased and then increased. In addition, the opening of many closed small mesopores increased the fractal dimension D2 of pore structure complexity, and provides an increase in specific surface area, but it has no significant relationship with the fractal dimension D1 of pore surface roughness.