Coal can be extracted from the earth either by surface mining or underground mining. Once coal has been extracted, it can be used directly (for heating and industrial processes) or to fuel power plants for electricity. If coal is less than 61 meters (200 feet) underground, it can be extracted through surface mining.
How does coal form underground?
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. … Coal is formed when dead plant matter decays into peat and is converted into coal by the heat and pressure of deep burial over millions of years.
How does underground coal mining work?
Underground mining involves opening one or more portals or shafts into the earth that follow or intercept coal seams that are too deep for surface mining methods. As the ‘room’ is mined, large ‘pillars’ of coal are left behind to support the weight of the overburden and rock layers above. …
Can coal burn underground?
Across the globe hundreds of fires burn low and slow on dirty fuel beneath the earth, smoldering for decades or even centuries. These fires are known as coal seam fires. They occur underground when a layer of coal in the earth’s crust is ignited.
How far do coal miners go underground?
Coal that occurs at depths of 55 to 90 m (180 to 300 ft) are usually deep mined, but in some cases surface mining techniques can be used. For example, some western U.S. coal that occur at depths in excess of 60 m (200 ft) are mined by the open pit methods, due to thickness of the seam 20–25 metres (60–90 feet).
What are the 4 types of coal?
Coal is classified into four main types, or ranks: anthracite, bituminous, subbituminous, and lignite.
Is Coal still being formed?
The process of coal formation is still taking place today, says Bailey. “The precursor to coal is called peat, and that is just uncompressed plant matter.” Peat accumulates in wet swampy environments known as mires, and that process is taking place today in areas such as Indonesia and even the Antiplano in the Andes.
Is coal mining still dangerous?
Coal mining is still dangerous. In 2010, West Virginia had the worst coal mining disaster in the US in 40 years, when an explosion killed 29 people. … That year, 3,242 people died in coal mining accidents. Coal mines have continued to have fires and explosions, killing hundreds of miners over the years.
How dangerous is underground mining?
Mines are often home to many dangerous gases including carbon monoxide, hydrogen sulfide, methane, and carbon dioxide. Due to the confined spaces, these gases are not always able to escape, building up within the mine. … The most common gas to cause underground mine explosions is methane.
Why is coal mining bad?
Along with adding to greenhouse gas pollution, burning coal emits toxic and carcinogenic substances into our air, water and land, severely affecting the health of miners, workers and surrounding communities.
Why can’t the Centralia fire be put out?
Because of these firefighting problems, fires like Centralia aren’t extinguished unless they directly impact nearby communities or are near a gas line or are otherwise imminently dangerous, Stracher says.5 мая 2010 г.
What is the longest burning fire in history?
Fueled by coal seams
A coal seam-fueled eternal flame in Australia known as “Burning Mountain” is claimed to be the world’s longest burning fire, at 6,000 years old. A coal mine fire in Centralia, Pennsylvania, has been burning beneath the borough since 1962.
Why are coal fires so hard to put out?
“Unlike timber, coal when it gets hot has massive thermal mass which is very hard to extinguish. … Coal fires are created by the interaction of carbon, oxygen and heat, which in turn produces carbon monoxide, carbon dioxide, and more heat to fuel the reaction.
What percentage of coal miners get black lung?
(Reuters) – More than 10 percent of America’s coal miners with 25 or more years of experience have black lung disease, the highest rate recorded in roughly two decades, according to a government study released on Thursday that showed cases concentrated heavily in central Appalachia.
How deep in the ground is coal?
Most of the world’s coal reserves are buried deep underground. Underground mining, sometimes called deep mining, is a process that retrieves coal from deep below the Earth’s surface—sometimes as far as 300 meters (1,000 feet).
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.