Rock dust is a pulverized rock, usually

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

, sprayed on walls inside underground

coal mine Coal mining is the process of extracting coal from the ground. Coal is valued for its energy content and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from ...

s to prevent

coal dust explosion Coal dust is a fine powdered form of which is created by the crushing, grinding, or pulverizing of coal. Because of the brittle nature of coal, coal dust can be created during mining, transportation, or by mechanically handling coal. It is a form o ...

s. The dust acts as a heat sink, keeps

coal dust Coal dust is a fine powdered form of which is created by the crushing, grinding, or pulverizing of coal. Because of the brittle nature of coal, coal dust can be created during mining, transportation, or by mechanically handling coal. It is a form o ...

levels down, and also prevents the incidence of

black lung disease Coal workers' pneumoconiosis (CWP), also known as black lung disease or black lung, is an occupational type of pneumoconiosis caused by long-term exposure to coal dust. It is common in coal miners and others who work with coal. It is similar to b ...

. Rock dust has been used since the early 1900s, but there have been technological improvements since then. U.S. federal regulations require that rock dust be applied in all underground areas of a coal mine to mitigate the propagation of a coal dust explosion. Prior to September 2010, U.S. federal regulation mandated that the nation’s coal mines maintain a total incombustible content (TIC) of at least 65% in nonreturn entries and at least 80% in the return airways. In September 2010, the U.S. Mine Safety and Heath Administration (MSHA) published an emergency temporary standard increasing the total incombustible requirement in intake airways to 80%, effective June 21, 2011. The 65% TIC requirement was based on an average particle size termed "mine-size dust," which was based on an average of representative samples collected from mines in the 1920s. To determine compliance with the federal regulation, mine inspectors systematically collect dust samples from sections of underground coal mines and send the samples to the MSHA

National Air and Dust Laboratory National may refer to: Common uses * Nation or country ** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen Places in the United States * National, Maryland, c ...

Mount Hope, West Virginia Mount Hope is a city in Fayette County, West Virginia, United States. The population was 1,414 at the 2010 census. History The community took its name from the local Mount Hope School. The Mount Hope Historic District and New River Company Ge ...

, for analysis of incombustible content.

References

{{reflist Calcium minerals Coal mining