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Examination of Classified Rock Dust (Treated and Untreated) Performance in a 20-L Explosion Chamber

Public Domain


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  • Personal Author:
  • Description:
    Mine explosions are caused by ignition of excessive accumulations of combustible dust and/or flammable gas mixed with air in the presence of an ignition source. Mines use a suite of control strategies to prevent methane and coal dust explosions¡Xone of which is to create an inert mixture of dusts throughout the mine by applying an incombustible dust, typically a limestone dust (rock dust), to the mine surfaces. Rock dusting is a primary measure to prevent propagating coal dust explosions in the US underground coal mines. Respirable dust exposure in coal mines is based on the measurement of total mass of airborne dust less than 10 £gm in size. Although rock dust is considered a nuisance dust, Continuous Personal Dust Monitors (CPDMs) does not distinguish between the coal dust and rock dust and it assess the total dust exposure. During application, the < 10 um limestone particles and coal dust particles can become suspended and carried by the ventilating air for long distances and be measured by the CPDMs. There is a concern in the industry that rock dust can be included in the CPDM measurements and make the samples noncompliant. Research conducted by the National Institute for Occupational Safety and Health (NIOSH) has found that all rock dust (RD) cakes after being wetted and then dried. To prevent rock dust from caking, several rock dust manufacturers have developed anti-caking rock dusts. The anti-caking additives used are typically fatty acids that make the rock dust hydrophobic and are added in very low quantities (< 1%). One function of the anti-caking additives that were developed is their usage as fluidizing agents. While this development will add to the rock dust fluidity, an inevitable problem may be the increased airborne re-entrainment of rock dust due to vehicle movement and foot traffic in the area. Thus, one consideration to reduce such exposure from rock dust is to remove the respirable size fraction (< 10 um) of the applied rock dust. This paper presents the results of experiments conducted to determine if a rock dust can still inert a coal dust explosion when the respirable (< 10 £gm) or inhalable (< 20 um) component of the particle size distribution is removed. Three different untreated rock dusts (untreated A, B, and C) with their treated counterparts (treated A, B, and C) were classified using mechanical sieves into several different-sized fractions, including < 10, 10,-20, 20-38, 38-53 and > 75 um. The relative inerting effectiveness of these size fractions were determined using the United States Bureau of Mines (USBM) 20-L explosion chamber. [Description provided by NIOSH]
  • Subjects:
  • Keywords:
  • Series:
    Mining Publications
  • Publisher:
    The Combustion Institute
  • Document Type:
    Text
  • Genre:
    Proceedings
  • Place as Subject:
  • CIO:
    National Institute for Occupational Safety and Health (NIOSH)
  • Division:
    PMRD - Pittsburgh Mining Research Division
  • Topic:
    Workplace Safety & Health
  • Location:
    North America
  • NIOSHTIC Number:
    nn:20054654
  • Citation:
    12th International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions, August 12-17, 2018, Kansas City, Missouri. Pittsburgh, PA: The Combustion Institute, 2018 Aug; :9211
  • Contact Point Address:
    Inoka E. Perera, Centers for Disease Control and Prevention National Institute for Occupational Safety and Health (NIOSH) 626 Cochrans Mill Road, Pittsburgh, PA 15236, USA
  • Email:
    eperera@cdc.gov
  • Federal Fiscal Year:
    2018
  • NORA Priority Area:
    Mining
  • Peer Reviewed:
    False
  • Source Full Name:
    12th International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions, August 12-17, 2018, Kansas City, Missouri
  • Collection(s):
  • Main Document Checksum:
    urn:sha-512:b2990e0a80ed339fd6364274134c1dd290b54c8f3538d3f2b3b0bee2e2f85ba542e07a8ff3b7e75849fc7d534813233e40ab4af01f1ec912e7bca4082cce69ae
  • Download URL:
  • File Type:
    Filetype[PDF - 1.18 MB ]
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