Beck T W, Seaman C E, Shahan M R, Mischler S E
T.W. Beck, C.E. Seaman, members SME, M.R. Shahan and S.E. Mischler are general engineer, mechanical engineer, mechanical engineer and mining engineer, respectively, at Centers for Disease Control and Prevention (CDC), National Institute for Occupational Safety and Health (NIOSH), Pittsburgh, PA, USA.
Min Eng. 2018 Jan;70(1):42-48. doi: 10.19150/me.7978.
Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce the risk of coal-dust-fueled explosions. The goal of this U.S. National Institute for Occupational Safety and Health study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust, smaller than 75 µm in diameter, in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity of 3.6 m/s (700 fpm). Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle should be operated at high fluid pressures to produce smaller droplets and move more air. These findings agree with past respirable dust control research, providing guidance on spray selection and spray array design in ongoing efforts to control airborne float dust over the entire longwall ventilated opening.
煤矿回风巷道中的浮尘在甲烷着火时会带来风险。在浮尘沉积到回风巷道之前控制空气中的粉尘，将使当前的岩粉喷洒措施更有效，并降低煤尘爆炸的风险。美国国家职业安全与健康研究所这项研究的目的是确定露天喷水在降低长壁采煤工作面风流中直径小于75微米的空气中浮煤尘浓度方面的潜力。本研究在一个无特征的巷道中评估了无限制喷水情况，该巷道以3.6米/秒（700英尺/分钟）的典型长壁采煤工作面风速进行通风。针对空心锥、全锥、扁平扇形、空气雾化和液压雾化喷嘴，在两种喷嘴方向和两种水压条件下进行了实验。重量法采样表明，在所有条件下，所有喷雾对空气中浮尘的去除效率平均为19.6%。结果表明，首选的喷嘴应在高流体压力下运行，以产生更小的液滴并带动更多空气。这些发现与过去可吸入粉尘控制研究一致，为在整个长壁通风口持续控制空气中浮尘的过程中进行喷雾选择和喷雾阵列设计提供了指导。
