Mining Publication: Technology News 461 - Coal Dust Explosibility Meter

Past research has shown that the accumulation of coal dust in underground coal mines can be rendered nonexplosible by adding sufficient quantities of inert rock dust, such as limestone dust. Federal regulations for underground coal mines require mine operators to dust mine corridors with an inert rock dust and maintain a total incombustible content of at least 65% in the entries and at least 80% in the returns, where the coal dust is expected to be finer in size. Currently, samples of the deposited coal and rock dust are collected for above ground analysis of the inert percentage, which consists of rock dust, ask, and moisture. The processing time for this analysis can be as long as 2 weeks. In addition, research has shown that measuring the incombustible percentage is not always sufficient to determine the explosibility of a sample, especially for finer coal dust. The National Institute for Occupational Safety and Health, Pittsburgh Research Center, has devised a prototype hand held instrument that can provide a direct assessment of the potential explosibility of a coal and rock dust mixture.