Coal dust explosions in underground coal mines are prevented by generous application of rock dust (usually limestone). 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.
Why is limestone powder 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.
What is coal dust used for?
For use in thermal power plants, coal is ground into dust using a device called a powdered coal mill. The resulting product, called powdered coal or pulverized coal, is then generally used in a fossil fuel power plant for electricity generation.
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.
Why do coal mines explode?
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.
How explosive is methane?
While any methane concentration within the flammability range has the potential to explode in the presence of an ignition source, a methane concentration of ~9.5% in air can produce the most damaging explosion.
What caused the Westray mine disaster?
Early in the morning beneath the small town of Plymouth, Nova Scotia, a methane gas leak into the Westray mine shaft from the Foord coal seam mixed with coal dust and caused in an explosion. … The nearby Allan mine, which closed in 1951, experienced eight methane explosions in its 40-years of operations.
What disease do coal miners get?
The two main types of pneumoconioses that affect miners are coal workers’ pneumoconiosis (CWP), commonly called black lung, and silicosis. CWP is associated with coal mining, but silicosis can affect workers in many types of mines and quarries, including coal mines.
Is coal dust harmful?
Exposure to coal mine dust causes various pulmonary diseases, including coal workers’ pneumoconiosis (CWP) and chronic obstructive pulmonary disease (COPD). 2. Coal miners are also exposed to crystalline silica dust, which causes silicosis, COPD, and other diseases.
Is coal a combustible dust?
Examples of combustible dust:
Coal and Other Carbon Dusts. Plastic Dust and Additives. Biosolids.
What are slurry ponds?
Any natural or artificial pond or lagoon for settling and draining the solids from washery slurry.
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.
Is methane easy to ignite?
Safety. Methane is nontoxic, yet it is extremely flammable and may form explosive mixtures with air.
What gas is responsible for most of the explosion in coal mines?