Coal dust

{{#badges:CoalSwarm}} Coal dust is a fine powdered form of coal, 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. Blasting at mountaintop removal (MTR) sites also expels coal dust and fly-rock into the air, which can disturb or settle onto nearby communities. The dust contains sulfur compounds, which corrodes structures and is a health hazard.

Coal dust is highly explosive and both accelerates and spreads smaller ignitions underground. Federal mine safety rules require removal of accumulated coal dust and the use of crushed limestone or "rock dust" to neutralize the combustibility of fine particles of coal that naturally cling to mine equipment, floors, pillars and roofs.

Explosions

Coal dust suspended in air is explosive -- coal dust has far more surface area per unit weight than chunks of coal, and is more susceptible to spontaneous combustion. As a result, a nearly empty coal store is a greater explosion risk than a full one. The worst mining accidents in history have been caused by coal dust explosions, such as the disaster at Senghenydd in South Wales in 1913 in which 439 miners died, the Courrières mine disaster in Northern France which killed 1099 miners, the Luisenthal Mine disaster in Germany, which claimed 299 lives in 1962, and the worst: the explosion at Benxihu Colliery, China, which killed 1549 in 1942. Such accidents were usually initiated by firedamp ignitions, the shock wave of which raised dust from the floor of the mine galleries to make an explosive mixture. The problem was investigated by Michael Faraday and Charles Lyell in the explosion at the colliery at Haswell County Durham of 1844, but their conclusions were ignored at the time.

The 1907 Monongah Mine Disaster of Monongah, West Virginia, which claimed the lives of 362 men and boys and is known as the worst mining disaster in American History, is thought to have been caused by the ignition of methane, which in turn ignited the highly flammable coal dust.

The main attempts at prevention include using safety lamps, adding stone dust coffers to mine galleries, watering workings, and ensuring efficient ventilation of all the workings.

Upper Big Branch Disaster

In Sep., 2010, it was reported that the search for a cause of April 2010's deadly Upper Big Branch Mine Disaster in West Virginia had turned up evidence of excessive coal dust in the Upper Big Branch Mine. Analysis of 1,803 dust samples collected by investigators after the blast showed that 79 percent were not in compliance with federal coal dust standards, according to Kevin Stricklin, director of the coal mine division of the federal Mine Safety and Health Administration. The finding, Stricklin said in a press briefing, suggests coal dust has "more potential to be involved in the explosion."

The sample results followed earlier reports that week stating excessive coal dust was seen in areas of the mine hit by the explosion a half-hour before the blast. Handwritten logs kept by two "fire bosses" - mineworkers who check for dangerous conditions before and after work shifts - noted excessive coal dust along conveyor belts as little as 30 minutes before the explosion. The logs were first obtained and reported by The Associated Press. Excessive coal dust is considered important in the investigation because the explosion traveled more than two miles, turning corners and spreading in opposite directions, suggesting the blast was fed, directed, and accentuated by an accelerant.

Massey Energy continues to insist that the explosion was likely caused by a sudden and massive infusion of methane gas through cracks in the mine floor. But a recent lawsuit challenging the MSHA from preventing Massey from doing its own investigation was dismissed by an administrative law judge. Two hundred thirty-five witnesses have been interviewed by MSHA, and investigators have 20 more people they'd like to question. But some are Massey managers who have objected to subpoenas issued by the West Virginia Office of Miners' Health, Safety and Training. Federal investigators do not have the power to compel testimony except in public hearings. Massey did not respond to requests for comment about its managers' resisting subpoenas. And Ron Wooten, the director of the West Virginia mine safety agency, said through a spokeswoman he had no comment.

A federal criminal investigation is also under way and a federal grand jury in Charleston, W.Va., has also been issuing subpoenas and taking testimony.

September 21, 2010: New compliance rules on coal dust issued

On September 21, 2010, MSHA director Joe Main announced plans to require underground mines to do more to control explosive coal dust under an emergency rule. The announcement came amid mounting evidence that coal dust played a role in the Upper Big Branch mine explosion in April. The change will raise to 80 percent the amount of pulverized stone or other inert material mines use to dilute coal dust in air intake tunnels, the same amount already required in return tunnels. Currently intakes need just 65 percent. Main says MSHA's change is based on federal research that shows decreasing the amount of coal dust in air intakes can prevent explosions.

Black Lung

Chronic exposure to the coal dust stirred up during mining can lead to black lung disease, or pneumoconiosis. It is a common affliction of coal miners and others who work with coal, similar to both silicosis (from inhaling silica dust) and to the long-term effects of tobacco smoking. Inhaled coal dust progressively builds up in the lungs and is unable to be removed by the body; that leads to inflammation, fibrosis, and in the worst case, necrosis, or the premature death of cells and living tissue.

Federal U.S. regulations of coal dust did not exist until In the Coal Mine Health and Safety Act of 1969, in which the U.S. Congress set up standards to reduce dust and the Black Lung Disability Trust Fund (BLDTF), which pays health benefits to coal miners afflicted with black lung. A miner who spent 25 years in underground coal mines has a 5-10% risk of contracting the disease.

BLDTF was instituted in 1978, and is funded through an excise tax on coal to support a trust fund covering health costs of affected workers. However the tax is not sufficient to cover all costs, and the BLDTF was given “indefinite authority to borrow” from the U.S. General Fund. By the end of FY 2008, the BLDTF had accrued nearly $13 billion in debt. In 2008, Congress partially “bailed out” the BLDTF.

Black lung took the lives of an estimated 10,000 miners worldwide over the last decade. Rates of black lung are on the rise, and have almost doubled in the last 10 years. The US National Institute for Occupational Safety and Health (NIOSH) reported that close to 9 percent of miners with 25 years or more experience tested positive for black lung in 2005-2006, compared with 4 percent in the late 1990s.

Community Exposure

A Dominion employee with an image of how the new 500-ft cooling towers will look.

On more than one occasion, coal dust from the Brayton Point Station has covered the nearby neighborhoods of Somerset, Massachusetts. The cities of Fall River, MA, New Bedford, MA, Brockton, MA, and Providence, RI are also within a thiry-mile radius of both Dominion's Brayton Point station and NRG's Somerset station.. The coal dust has been carried from the Station while deliveries of coal were unloaded from ships on windy days. On October 29, 2008, coal dust covered nearby Ripley Street where residents reported having coal dust in their homes despite the windows being closed. A 45,000 ton shipment of coal was unloaded overnight and the community woke up to the dust the following morning.

The most recent of these incidents was early November 2009, when thirty-six homes were covered. This was another occasion when residents woke up in the morning to find their neighborhood covered in coal dust. In a news interview, resident David Gasperini said, "I can clean stuff, but I can't clean our children's lungs, our animals’ lungs and stuff like that. Who knows if 20 or 30 years from now if anybody is going to end up getting any kind of diseases or anything from this stuff." Dominion blamed an extra-dry shipment of coal combined with winds. The company said it would no longer unload coal in winds over 15 miles per hour. Dominion sent insurance adjusters to the affected neighborhood and said they would reimburse the residents for the clean up.

Articles & resources

SourceWatch resources

• Coal mining accidents
• Health effects of coal
• Longwall mining
• Mine Safety
• Monongah Mining Disaster
• Sago Mine Disaster
• Upper Big Branch Mine Disaster