U.S. Code of Federal Regulations 30 CFR 75.402 and 75.403 require 80% total incombustible content to be maintained within 40 feet of the coal mine face via the liberal application of rock dust. Unfortunately, this application of rock dust limits miners' visibility downwind and can increase the miners' exposures to a respirable nuisance dust. Wet rock dust applied as a slurry is, at times, used to negate these negative effects. Although this aids in meeting the total incombustible limits, the slurry forms a hard cake when dried and no longer effectively disperses as needed to suppress a coal dust explosion. As a result, a dry rock dust must be reapplied to maintain a dispersible layer. Therefore, researchers from the National Institute for Occupational Safety and Health (NIOSH) have been working towards finding and testing a foamed rock dust formulation that can be applied wet on mine surfaces and remain dispersible once dried which minimizes the likelihood of mine disasters, including mine explosions. The initial tests were aimed at discerning dispersion characteristics of three different foamed rock dusts via the NIOSH-developed dispersion chamber and led to identification of a two-part foam with adequate dispersion characteristics. The current study was conducted to assess the robustness of the two-part foamed rock dust. Through a series of laboratory-scale experiments using the dispersibility chamber, the effects of testing conditions and product formulations on the foam's dispersibility was determined. Some of the tested variables include: exposing the foam to high humidity, varying the component levels of the foamed rock dust, altering the rock dust size distribution, and varying the rock dust types. Further pilot-scale tests examined the atmospheric concentrations of dust via personal dust monitors downwind of foamed rock dust production and application. Additionally, product consistency was recorded during pilot-scale testing at key points in the formulation and application. The results of these experiments will be discussed in this paper.

美国联邦法规 30 CFR 75.402 和 75.403 要求通过大量施用岩粉将 80% 的不可燃物含量保持在煤矿工作面 40 英尺范围内。不幸的是，这种岩尘的应用限制了矿工顺风的能见度，并且会增加矿工暴露于可吸入的有害粉尘的风险。有时，以泥浆形式使用的湿岩粉可以抵消这些负面影响。尽管这有助于满足总不可燃极限，但浆体在干燥时会形成硬饼，并且不再根据抑制煤尘爆炸的需要有效分散。因此，必须重新涂抹干燥的岩粉以保持可分散层。所以，美国国家职业安全与健康研究所 (NIOSH) 的研究人员一直致力于寻找和测试一种泡沫岩粉配方，该配方可以湿涂在矿井表面，并在干燥后保持可分散性，从而最大限度地减少发生矿难（包括矿井爆炸）的可能性。最初的测试旨在通过​​ NIOSH 开发的分散室辨别三种不同泡沫岩粉的分散特性，并导致识别出具有足够分散特性的两部分泡沫。目前的研究是为了评估两部分泡沫岩尘的坚固性。通过一系列使用分散室的实验室规模实验，确定了测试条件和产品配方对泡沫分散性的影响。一些测试变量包括：将泡沫暴露在高湿度下、改变泡沫岩粉的成分水平、改变岩粉粒度分布以及改变岩粉类型。进一步的中试规模测试通过泡沫岩尘生产和应用顺风的个人粉尘监测器检查了大气中的粉尘浓度。此外，在配方和应用的关键点的中试规模测试期间记录了产品的一致性。这些实验的结果将在本文中讨论。进一步的中试规模测试通过泡沫岩尘生产和应用顺风的个人粉尘监测器检查了大气中的粉尘浓度。此外，在配方和应用的关键点的中试规模测试期间记录了产品的一致性。这些实验的结果将在本文中讨论。进一步的中试规模测试通过泡沫岩尘生产和应用顺风的个人粉尘监测器检查了大气中的粉尘浓度。此外，在配方和应用的关键点的中试规模测试期间记录了产品的一致性。这些实验的结果将在本文中讨论。