Frequent question: Why limestone powder is often scattered around a coal mine?

Limestone powder, known as rock dust, is spread throughout the mine workings on a regular basis. … When explosions do occur, the dispersed limestone powder absorbs the heat generated from the explosion and will either stop the chain reaction or reduce the intensity of the explosion.

Why is limestone powder used in coal mines?

Coal dust explosions in underground coal mines are pre vented by a generous application of rock dust (usually lime stone). If an explosion should occur, the rock dust disperses, mixes with the coal dust and prevents flame propagation by acting as a thermal inhibitor or heat sink.

What causes explosions in coal mines?

Coal mine explosions are generally caused by either methane or coal dust. Methane gas is a byproduct of coal. It can build up over time in coal mines when there are not enough other types of gases to dilute it to prevent an explosion. … Explosions happen when the methane comes in contact with a heat source.

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What is rock dusting in coal mines?

Rock dust (generally pulverized limestone dust) serves as a heat sink material that prevents or suppresses a propagating coal dust explosion through the absorption of thermal energy from the heated gases and absorption of radiant energy, which reduces the preheating of unburned coal particles ahead of the flame front.

Is coal dust hazardous?

What makes coal dust so dangerous? Coal dust particulates (tiny pieces of coal) are of particular concern because they contain heavy metals which are toxic at low concentrations. They include lead, mercury, nickel, tin, cadmium, mercury, antimony, and arsenic, as well as radio isotopes of thorium and strontium.

What are the two main types of limestone?

Generic limestone categories

  • Bituminous limestone.
  • Carboniferous Limestone – Limestone deposited during the Dinantian Epoch of the Carboniferous Period.
  • Coquina – A sedimentary rock that is composed mostly of fragments of shells.
  • Coral rag.
  • Chalk – A soft, white, porous sedimentary rock made of calcium carbonate.

Can you burn coal dust?

Preventive procedures, however, must rely on fundamental knowledge concerning the behavior of coal dust combustion. … In addition, it is known that coal particles do not always burn simply as shrinking spheres, but can burn internally and form cenospheres (hollow spheres) as well.

What is the average lifespan of a coal miner?

The average life expectancy in the coal mines for those starting work at 15 y was found to be 58.91 y and 49.23 y for surface and underground workers respectively. In the coloured/metal mines they were 60.24 y and 56.55 y respectively.

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How often do coal miners die?

The yearly average in coal mining decreased to 30 fatalities from 2001-2005, though 60 to 70 miners still die each year in the U.S. coal and non-coal mining industry.

What percentage of coal miners get black lung?

One in ten underground coal miners who have worked in mines for at least 25 years were identified as having black lung, according to a new report by the National Institute for Occupational Safety and Health (NIOSH) published in the American Journal of Public Health .

How does removing the overburden during coal extraction affect the environment?

Strip mining eliminates existing vegetation and alters the soil profile, or the natural soil layers. Mining disturbs and may even destroy the beneficial micro-organisms in the topsoil. Soil also may be damaged if reclamation operations mix the topsoil with subsoils, diluting matter in the surface soil.

What are slurry ponds?

Any natural or artificial pond or lagoon for settling and draining the solids from washery slurry.

Is Coal bad for your lungs?

In addition, respirable crystalline silica in coal ash can also lodge in the lungs and cause silicosis or scarring of lung tissue, which can result in disabling and sometimes fatal lung disease and cancer.

How does coal dust affect the lungs?

It is common in coal miners and others who work with coal. It is similar to both silicosis from inhaling silica dust and asbestosis from inhaling asbestos dust. Inhaled coal dust progressively builds up in the lungs and leads to inflammation, fibrosis, and in worse cases, necrosis.

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How do I get rid of coal dust?

Using a medium stiffness 2″ bristle brush together with the vacuum should remove more than 95% of the residual coal dust. Once an initial cleaning is completed, a 2nd pass using compressed air can be used to blast loose nearly all remaining dust, while sucking it into the HEPA vacuum.

Coal mine