Coal mining dust hazard

The research authority vested in NIOSH has helped to fuel advances by NIOSH and its partners against a broad range of workplace hazards, including lead, asbestos, dioxin, coal mine dust, traumatic injuries, workplace violence, latex allergy, and occupational lung disease associated with butter flavorings. 

Coal Mine Explosions Measures for Preventing and Arresting Them. As a result of investigations conducted by various European organizations and individuals before and after WWI, the following methods were recommended in Europe to combat expln hazards a)Infusion of water under pressure into the coal before it is broken down b)Spraying with water all accessible roads, roof and sides of mines with water in sufficient amt to ensure that the dust contains at least 30% of w c)Instead of water an incombustible dust can be used for spraying. It should be done is such a manner that the amt of coal dust in mixts does not exceed 50% (Refs 12, 22, 23 31)... 

Following the historical development of electrical engineering and explosion protection, zone classification was the objective of national standards and installation rules. Most of the leading industrial countries established an installation practice for chemical plants and the oil and gas industry with two or three zones for areas hazardous due to gas- or vapour-air mixtures and two zones for areas with hazardous dust-air mixtures. Apart from this philosophy, the coal mining industry in most countries tends to avoid an area classification and defines only one category of explosion protection ( firedamp-proof ). More recent standards or directives present a three-zone concept for areas endangered by combustible gas- (vapour-, mist-) air mixtures and dust-air mixtures in industrial plants (other than coal mines). 

Mine fire is one of the largest hazards in coal mine, which not only makes coal mine suffer tremendous losses in physical material, but also is the main cause of miners casualty (Xian et al. 2001). The spontaneous combustion of coal is one of main reasons to mine fire. According to statistics, the mines with spontaneous combustion tendency account for 51.3% of state owned key coal mines in China. There are poisonous material such as CO, COj and dust in the course of coal spontaneous combustion, and so on. The statistical results show that over 95% victims died from above poisonous smoke and gas in mine fire (Jukka et al. 1999). 

Occupational diseases that affect the health of workers, to cause premature workers lose the ability to work the main factors. Mine occupational hazards in dust (coal dust, rock dust, cement dust, etc.), chemicals (nitrogen oxides, carbon oxides, sulfur dioxide, hydrogen sulfide, etc.) and physical factors (noise, vibration, thermal radiation, high temperature, etc.) three categories. Which is the most serious to dust hazards caused by pneumoconiosis. 2009,14,495 cases of pneumoconiosis new cases, the CWP and sand lung accounted for 91.89%. The incidence of pneumoconiosis shorten the length of service, the mass of pneumoconiosis... 

Effect of contact on reaction rate. An effect similar to a concentration increase occurs if a solid reactant is very finely divided, which essentially increases concentration by increasing the surface area at which reactions can occur. We don t think of flour as an explosive substance, but a spark can set off tbe explosion of flour suspended in the air. Dust explosions are a hazard in grain storage and coal mines. 

As a result, hazards such as mine wall failure, roof collapse, and the release of gases such as methane (firedamp) as well as coal dust which can result in explosions are endemic to coal mines. Although most of these risks have been reduced in the past five decades, multiple fatality accidents still occur. 

Dust explosions have been observed in the industry for a long time. Even normally inflammable materials such as metals may cause devastating explosions in the powder form when distributed finely in the air, and this is activated merely by a low-energy igniting source. Hence, all the more hazardous is a dust of combustible materials such as are common in coal mines and flourmills In the plastics industry, most of the manufacturing plants and processing shops run the risk of dust explosion due to the airborne powder. 

Chemical (Hazard Information and Packaging for Supply) (Amendments) Regulations 2000 Coal Mines (Respirable Dusts) Regulations 1975 Combination Acts Confined Space Regulations 1997... 

SAFETY NOTE Disastrous coal mine explosions do not always result from ignition of a gas. Bituminous ("soft") coal dust suspended in air may be ignited by a match, producing a violent explosion, the rate of pressure rise reaching as much as 40 atm/second. The pressure increase results from the rapid expansion of the gaseous products of the reaction and air, caused by the heat evolved from the combustion reaction. In general, you must regard combustible dusts suspended in air as explosion hazards. 

Coal workers pneumoconiosis is also a concern at surface coal mines and preparation plants, but not to the extent as in underground mines for high-risk occupations. Dust control measures for surface mines (primarily for dust generated from drilling, hauling, and crushing) are different from the ones implemented in underground mines, and these will be covered in the section on control of hazards. 

Airborne particulate matter may be associated with many carcinogenic and other toxic agents. Hazardous materials include coal dust, fly-ash from power stations, metals and metal oxides from mining, extraction and refining and materials used as catalysts in industrial processes, as well as particulate matter from, for example, diesel exhausts. 

Explosion of coal dusts in mines is described in Vol 3 of Encycl, pp C358 C359 under "Coal Dust and Its Uses and "Coal Dust Explosion Hazards from Its Uses . 

Early in the present century attention was drawn to the danger created in mines by coal-dust. Until 1906 it was believed in France that this hazard could be entirely explained by the presence of firedamp, but even in the early nineteenth century it was supposed that a suspension of coal-dust in the air may also explode. Thus, as early as 1803, it was suggested in the U.S.A. that coal-dust might be involved in mine explosions [17]. In 1844, Faraday drew attention to this (according to J. Taylor and Gay [4]), and later Galloway [18] discussed the coal-dust danger. By the end of the last century the possibility of explosion was proved experimentally, but it was believed that an explosion of methane-air mixture is necessary to initiate a coal-... 

It was also obvious that the immediate cause of explosion of both methane and coal-dust may be the use of explosives in mines. Particular attention was paid to the hazard involved in the use of blackpowder in mines (e.g. in Great Britain H.M. Commissioners [19] Royal Commission on Explosions [20]). 

Dust resulting from operations such as mining coal, production of talc or face powder, milling grain and sawing wood are all fire, explosion and/or health hazards. Such dusty conditions can be alleviated or controlled by water sprays containing small amounts of Aerosol GPG Surfactant. 

S.K. Shaw D.W. Woodhead, Safety in Mines Research Report No 131 (1956) CA 50, 16110 (1956) (Expln hazards from localized deposits of coal dust) 4)N. Brunzel, MittVerGrosskessel-besitzer, No 42, 179-201 (1956) CA 50, 17377 (1956) (A review with 20 refs covering fundamentals of coal dust explns) 5)H. Hanel, Technik 11, 785-92 (1956) CA 51, 6157 (1957) (Flammability and expln danger of dusts, including coal dust) 6)Sax (1957), 490 (Expln hazard slight when exposed to flame and fire hazard,moderate when exposed to heat can react with oxidizing materials)... 

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