Abstract:
Coal seam water injection is a common method to reduce dust in coal working face and prevent gas outburst.However,the anthracite is highly hydrophobic and the coal seam water injection effect is limited. For the purpose of water injection in coal seam,the electrochemical method can significantly improve the surface wetta-bility and development of pore and fracture of anthracite. Anthracite in Sihe Coal Mine of Jincheng,China was electrochemically modified with 0. 05 mol / L Na2SO4 electrolyte,and the water absorption,surface properties and pore characteristics before and after modification were tested and analyzed. The results show that after the elec-trochemical modification, the changed water content of the coal sample increased first and then decreased,and finally gradually tended to be stable with time. Compared with the unmodified anthracite sample,the natural water absorption of the coal samples in the anode,middle and cathode regions increased by 72. 57% ,87. 14% and 102. 29% respectively. The oxidation reaction occurred in the electrochemically modified anode region,the aro-matic hydrocarbons and aliphatic hydrocarbons in the coal sample were oxidized to oxygen-containing functional groups,the wettability was enhanced,and the dynamic contact angle of coal-water was reduced by 25. 96°,the zeta potential was 21. 38 mV. The reduction reaction occurred in both the middle and cathode regions,so that the alkyl branch was detached,the aromatic ring was cracked,and the relative content of oxygen was increased,the coal-water dynamic contact angle was decreased by 20. 40° and 15. 21° respectively,the zeta potential was -68. 47 mV and -80. 01 mV respectively. Under the action of H+and electrophoresis generated in the electrochemical process,some carbonate minerals filled in the anthracite pores were dissolved and transported,and finally left the coal,thus,some micro-pores produced the “reaming effect”,and the average pore diameters of the anode,middle and cathode regions increased by 3. 77 times,3. 67 times and 5. 02 times respectively,and the permeability of water was improved. The research results in this paper provide a basis for the electrochemical modification of anthracite coal seam water injection.