Experimental study on increasing the permeability of coal body based on AEO-9 compounding solution

The chelating agent could deconvolute the metal ions in the coal body into a free state and communicate with the pores of the coal body. However, as the mining depth increased, the chelating agent could not effectively wet the coal body. Therefore, it was particularly important to select a solution that could both communicate the pores of the lignite and increase the permeability radius in the coal body. In this paper, a wetting agent was added on the basis of chelating agent to improve the wettability of aqueous solution to coal using compounding solution. The results showed that the Ca2+, Mg2+, and Fe2+/3+ leaching effect was significant under the AEO-9 compounding system. When the quality concentration of the wetting agent and the chelating agent was 0.05%, and the compounding ratio was 1:1, the contact angle between coal and solution surface was 24.47°. At this time, the average pore diameter was 4.8636nm, the pore specific surface area was 0.8717m²/g. The number of peaks in the pore distribution of coal samples increased and appeared near 1.44nm, 1.79nm and 2.24nm, respectively. The minerals in the coal dissolved and the internal micropores expanded into medium or large pores.