Abstract
Currently, spraying is a main means for dust prevention and control in underground coal mines. The dust‐suppression efficiency via spraying is highly correlated with the wettability of coal dusts. There are many factors affecting the wettability of coal dust, among which coal’s metamorphic degree has great influence. In order to gain in‐depth knowledge of the effects of coal metamorphic degree on coal dust wettability and the dust‐suppression efficiency via spraying, 6 coal dust samples with different metamorphic degrees were collected and used in the study. In the experiments, the microproperties, wetting performance, and dust‐suppression efficiency via spraying were measured. According to the experimental results of coal’s microproperties, with the improvement of metamorphic degree, the content of hydrophilic oxygen‐containing functional groups on the surface, the surface roughness, the specific surface area, and the interpore diameter all decreased. In addition, as coal’s metamorphic degree was enhanced from lignite to meager‐lean coal, the wettability of the coal dust dropped. On the other hand, as the metamorphic degree of coal quality continued to be improved to anthracite, the wettability of the coal dust increased instead. The measured results revealed that the dust‐suppression efficiency via spraying was highly correlated with the wettability of coal dust. The coal dust with better wettability exhibited higher dust‐suppression efficiency via spraying. With the increase of water‐supply pressure, the effect of coal dust wettability on the dust‐suppression efficiency via spraying was weakened, and the difference of dust‐suppression efficiency among different coal dust samples was narrowed.
Highlights
Coal is an important natural resource and plays a decisive role in the development of national economy [1,2,3,4]
The number of pneumoconiosis cases in coal mining industry accounts for 40% of the total number of the reported occupational cases. erefore, it is extremely urgent to adopt high-efficiency dust-suppression and dust-control measures to reduce the dust concentration in coal production sites [14,15,16,17,18]
In order to illustrate the influence mechanism of the internal structure of coal dust on the wettability, many microcharacteristic parameters were acquired in the test, including surface functional groups, surface roughness degrees, specific surface areas, and internal pore diameters of coal dust samples with different metamorphic degrees
Summary
Coal is an important natural resource and plays a decisive role in the development of national economy [1,2,3,4]. There has been a great progress in the studies on the wettability of coal dust, especially in the influence mechanism of the chemical composition and the metamorphic degree on the wettability of coal dust. Based on the combination of the contact angle and reserve osmosis experiments, the influence mechanism of the metamorphic degree on the wettability of coal dust was analyzed on a microscopic level. On this basis, the customdeveloped dust-suppression experimental platform via spraying was used to investigate the dust-suppression efficiencies for the coal dust particles with different metamorphic degrees. The customdeveloped dust-suppression experimental platform via spraying was used to investigate the dust-suppression efficiencies for the coal dust particles with different metamorphic degrees. e effect of the metamorphic degree of coal dust on the dust-suppression efficiency via spraying was evaluated. e results in this study can provide insightful reference and guidance for the design of spraying-based dust-suppression scheme and theoretical prediction of dustsuppression efficiency via spraying in underground coal mines
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