Reed W R, Zheng Y, Klima S, Shahan M R, Beck T W
Research mining engineer, associate service fellow, mining engineer, mechanical engineer and research engineer, respectively, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health (CDC-NIOSH), Pittsburgh Mining Research Division, Pittsburgh, PA, USA.
Trans Soc Min Metall Explor Inc. 2017;342(1):72-82. doi: 10.19150/trans.8110.
Testing was conducted to determine the ability of foam to maintain roof coverage in a simulated longwall mining environment. Approximately 27 percent of respirable coal mine dust can be attributed to longwall shield movement, and developing controls for this dust source has been difficult. The application of foam is a possible dust control method for this source. Laboratory testing of two foam agents was conducted to determine the ability of the foam to adhere to a simulated longwall face roof surface. Two different foam generation methods were used: compressed air and blower air. Using a new imaging technology, image processing and analysis utilizing ImageJ software produced quantifiable results of foam roof coverage. For compressed air foam in 3.3 m/s (650 fpm) ventilation, 98 percent of agent A was intact while 95 percent of agent B was intact on the roof at three minutes after application. At 30 minutes after application, 94 percent of agent A was intact while only 20 percent of agent B remained. For blower air in 3.3 m/s (650 fpm) ventilation, the results were dependent upon nozzle type. Three different nozzles were tested. At 30 min after application, 74 to 92 percent of foam agent A remained, while 3 to 50 percent of foam agent B remained. Compressed air foam seems to remain intact for longer durations and is easier to apply than blower air foam. However, more water drained from the foam when using compressed air foam, which demonstrates that blower air foam retains more water at the roof surface. Agent A seemed to be the better performer as far as roof application is concerned. This testing demonstrates that roof application of foam is feasible and is able to withstand a typical face ventilation velocity, establishing this technique's potential for longwall shield dust control.
进行了测试以确定泡沫在模拟长壁开采环境中保持对顶板覆盖的能力。约27%的可吸入煤矿粉尘可归因于长壁掩护支架移动，而针对该粉尘源开发控制措施一直很困难。应用泡沫是针对该粉尘源的一种可能的粉尘控制方法。对两种泡沫剂进行了实验室测试，以确定泡沫附着在模拟长壁工作面顶板表面的能力。使用了两种不同的泡沫生成方法：压缩空气和鼓风。利用一种新的成像技术，使用ImageJ软件进行图像处理和分析得出了泡沫对顶板覆盖的可量化结果。对于在3.3米/秒（650英尺/分钟）通风条件下的压缩空气泡沫，施用后三分钟时，98%的A剂在顶板上保持完好，而95%的B剂保持完好。施用后30分钟时，94%的A剂保持完好，而只有20%的B剂留存。对于在3.3米/秒（650英尺/分钟）通风条件下的鼓风泡沫，结果取决于喷嘴类型。测试了三种不同的喷嘴。施用后30分钟时，74%至92%的A泡沫剂留存，而3%至50%的B泡沫剂留存。压缩空气泡沫似乎能在更长时间内保持完好，且比鼓风泡沫更易于施用。然而，使用压缩空气泡沫时从泡沫中排出的水分更多，这表明鼓风泡沫在顶板表面保留了更多水分。就顶板施用而言，A剂似乎表现更好。该测试表明，在顶板上施用泡沫是可行的，并且能够承受典型的工作面通风速度，确立了该技术在长壁掩护支架粉尘控制方面的潜力。
