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Engineering Controls Database

Best Practices for Dust Control in Coal Mining – Continuous Mining Operations – Intake Airways

Respirable dust exposure has long been known to be a serious health threat to workers in many industries. In coal mining, overexposure to respirable coal mine dust can lead to coal workers’ pneumoconiosis (CWP). CWP is a lung disease that can be disabling and fatal in its most severe form. In addition, miners can be exposed to high levels of respirable silica dust, which can cause silicosis, another disabling and/or fatal lung disease. Exposure to coal mine dust may also increases a miner’s risk of developing chronic bronchitis, chronic obstructive pulmonary disease, and pathologic emphysema.

Once contracted, there is no cure for CWP or silicosis. The goal, therefore, is to limit worker exposure to respirable dust to prevent development of these diseases.
CWP contributed to the deaths of 10,406 U.S. miners during 1995–2004 [NIOSH 2008]. Pneumoconiosis continues to be a very serious health threat to underground coal mine workers. If not given proper attention, intake air can be a problem source of exposure to workers at the mining face.

The average concentration of respirable dust in intake air must be kept at or below 1 mg/m3 within 200 ft outby the working face. However, to maintain consistent dust control in the face area, MSHA recommends that intake concentrations be less than 0.5 mg/m3 [Shultz and Fields 1999]. Maintaining this concentration is not usually difficult, but requires attention from mine operators to address activities that can raise intake air dust levels. Typically, high levels of intake dust are sporadic and brief in nature due to activities in the intake entries that may take place over the course of a working shift. These sporadic activities include:

• Delivery of supplies and/or personnel
• Moving equipment in intake
• Rock dusting
• Scoop activity
• Construction activity

In addition, the belt entry can be used to bring intake air to the working faces and is a potential source of dust generation.
If intake dust levels are high, the following steps can be taken to maintain dust levels to a minimum

• Good housekeeping practices will help keep intake entries free of debris, equipment, and supplies.
• Supply delivery, scoop activity, stopping construction, and rock dusting should be dedicated to nonproduction shifts.
• If haulage activities must take place during a production shift, the haulage roadways should be kept damp at all times. Since water will likely evaporate in the ventilation air, a hygroscopic salt or effective dust-allaying agent should be used [Ondrey et al. 1994]. Keeping dust dampened in the main intake entries will limit dust entrained by activity in these entries.
• Equipment should be parked in crosscuts to keep main airways clear of obstruction.

When belt air is used for face ventilation, dust generated in the belt area should be controlled. Potts and Jankowski [1992] measured the dust level impact of using belt air for face ventilation on continuous miner sections. Controls at the belt head helped maintain low dust levels in the belt entry. Automated sprays were used to suppress dust at the section-to-main transfer point. A belt scraper equipped with sprays controlled dust by cleaning the outside surface of the belt after the coal had been transferred to the main belt.
NIOSH [2010]. Information circular 9517. Best practices for dust control in coal mining. Morgantown, WV: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2010-110.

NIOSH [2008]. Work-related lung disease surveillance report, 2007. Morgantown, WV: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2008143a.

Ondrey RS, Haney RA, Tomb TF [1994]. Summary of minimum dust control parameters. In: Proceedings of the Fourth Symposium on Respirable Dust in the Mineral Industries (Pittsburgh, PA, November 8–10, 1994).

Potts JD, Jankowski RA [1992]. Dust considerations when using belt entry air to ventilate work areas. Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9426.

Schultz MJ, Fields KG [1999]. Dust control considerations for deep cut mining sections. SME preprint 99-163. Littleton, CO: Society for Mining, Metallurgy, and Exploration, Inc.
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