Abstract
Gas-sealing coatings on coal mine roadway walls can effectively repress gas emission and are of importance to the safe operation of coal mining. In this study, the performance of coal fly ash (CFA)-based gas-sealing coatings was investigated, including the aspects of drying time, air tightness, impermeability, flame retardancy and antistatic properties. The results show that coating No. 25 with 60 g ultrafine CFA and 50 g emulsion (curing at 22 °C) had the best air tightness, with a permeability coefficient of 2.95 × 10−13 cm2/(s·Pa). The data obtained through the self-developed air tightness test device agreed well with the detection results of the gas permeameter, thus verifying the accuracy and reliability of the device. The impermeability, flame retardancy and antistatic properties of coating No. 25 conformed the requirements of voluntary national standards GB/T 23445-2009 and coal industry standard MT113-1995, respectively. The CFA-based gas-sealing coating in the pilot test reduced the gas emission intensity by 40%–50%. It could have wide applications in coal mine roadway walls.
Highlights
Most coal mines in China are moderately or highly gassy mines, and gas explosions have resulted in heavy losses to the coal industry and the lives of miners [1]
To reduce the hazards induced by gases, ventilation measures are used in the coal mining process to dilute gas concentrations in roadways [2,3]
A pilot experiment was carried out on a coal mine roadway wall, and the results proved that the coal fly ash (CFA)-based gas-sealing coating is effective and applicable
Summary
Most coal mines in China are moderately or highly gassy mines, and gas explosions have resulted in heavy losses to the coal industry and the lives of miners [1]. To reduce the hazards induced by gases, ventilation measures are used in the coal mining process to dilute gas concentrations in roadways (i.e., gases emitted into the air through methane ventilation) [2,3]. Such measures give rise to serious environmental pollution problems [4]. Another measure used to prevent and control gas disasters is roadway wall blocking, that is, spraying gas-sealing coatings on roadway walls, which blocks the gasses’ leakage through roadway surfaces. Underground gas-sealing coatings in non-Chinese coal mines are mostly made up of organic materials, such as polyurethanes, with good sealing effect [7]
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