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Coal Mine. Quarry. Mining and Quarrying. Mining vs. Quarrying. - Though the words "mining" and "quarrying" often are used interchangeably, they are separate words with separate but closely related meanings.
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Coal Mine Quarry Mining and Quarrying
Mining vs. Quarrying • - Though the words "mining" and "quarrying" often are used interchangeably, they are separate words with separate but closely related meanings. • - Mining, strictly speaking, is the practice of extracting minerals from pits or excavations. Quarrying is the surface-mining of limestone, sandstone and other materials.
Mining • Many rocks and minerals must be mined in order to extract the valuable elements they contain • Geologists use the term “ORE” to describe a mineral deposit large enough and pure enough to be mined for a profit.
What is Coal? • Coal is a combustible, black sedimentary rock composed predominantly of carbon. It is formed out of plant matter that accumulated at the bottom of swamps millions of years ago, during the Carboniferous Period. At this time, the earth's climate was extremely favorable for plant growth.
How Did Coal Form? • Organic matter accumulated in stagnant swamps which were low in oxygen and thus inhibited decomposition. Eventually, seas rose or the land subsided and the swamps were submerged. Sand, clay and other debris at the bottom of the seas buried the organic material.
How Did Coal Form? • Over thousands of years, the organic material was compacted under the weight of the overlying sediments and was transformed into coal (Figure 1). Coal deposits are now found buried beneath layers of sandstone, limestone and shale all over the world.
How Does Coal Form? Peat Lignite Bituminous Anthracite
Anthracite Coal Fields in Eastern Pennsylvania Where Coal is Found in Pennsylvania
- Last year 93% of mined coal is used by electric utility companies. - Coal is also used to make plastic and steel. - Coal can be burned just as it comes from the ground or converted into liquid and used in traditional gasoline engines. Coal and Its Use
- Last year 67% of the coal was produced from surface mines and 33% from underground mines. - In the last 20 years mines have become largerbut fewer in number. Mining Coal
Types of Mining • The mining method used to extract a particular mineral deposit depends on the type of deposit and the economics involved with extraction • When the deposit occurs in veins or beds that extend deep into the Earth’s crust or when the overburden (overlying soil and rocks) is very thick, underground mining methods are required. When the deposits are near the surface, surface mining methods such as open pit or quarrying may be most efficient.
Surface Mining Surface Mining is accomplished by the removal of overburden from the coal seam and then blasting and removing the coal. Area surface mines are usually located in flat terrains, while contour mining occurs in mountainous terrain and follows the coal seam along the side of a the hill. Open pit mining is usually found where coal seams are think, reaching depths of several hundred feet. Types of Modern Mining
Surface Mining Equipment Dragline
Surface Mining Equipment Large Capacity Dump Truck
Types of Modern Coal Mining Underground Mining • This drawing depicts the three types of underground mines – shaft mines, slope mines, and drift mines. The decision of what type of mine to construct depends on the depth of the coal seam and the surrounding terrain. • Almost all underground mines are less than 1000 feet deep, but some mines reach depths of 2000 feet.
Most underground coal is mined by the room and pillar method, whereby rooms are cut into the coal bed leaving a series of pillars, or columns of coal, to help support the mine roof and control the flow of air. Types of Underground Mining
Underground Mining Equipment Continuous Mining Machine
Underground Mining Equipment Coal Conveyors
Underground Mining Equipment Coal Conveyors
Coal mining in PA began in the mid-1700’s and fueled the colonial iron industry PA is now the 4th largest coal producer Two kinds of coal are mined in PA – anthracite and Bituminous Over 64.5 million tons of bituminous coal were mined in 2006 and 1.5 tons of anthracite. Coal Mining in Pennsylvania
10 billion tons of Bituminous Coal have been produced in PA during over 200 years of mining Geologic history in PA resulted in nearly flat layers of bituminous coal deposits in western PA. In between layers of coal are layers of sandstone, shale, and limestone Bituminous Coal Mining in PA
All of the nation’s anthracite coal is found in eastern PA. Anthracite coal seams are locked in the folded layers of rock that make up the geology of northeastern PA. The geology often made it difficult to mine. Anthracite Coal Mining in PA
Anthracite production in PA reached its peak in 1917 when more than 100 million tons of coal were mined from underground operations in the Wilkes-Barre/Scranton region. Large scale underground mining essentially ended in 1959 when in this region as a result of the Knox Mine Flood. The Susquehanna River literally disappeared into the mines. The Lehigh Valley Railroad was relocated to move 30 rail cars and 400 mine cars to plug the hole caused by the breakthrough. Anthracite Coal in PA
Coal mining disturbs large quantities of land and can cause severe environmental problems if they are not addressed. Erosion can cause streams to become clogged with sediment. Top soil can be lost. Sulfur-bearing (Pyrite) rocks can cause acid mine drainage. And, if left unreclaimed, a mine can leave dangerous highwalls and many years of off site pollution problems. The photo to the left looks like typical farmland; however, just five years before it was an active surface mine that has been reclaimed. Environmental Problems
The Surface Mining Control and Reclamation Act of 1977, the law that regulates coal mining throughout the country, established a coordinated effort between the states and the federal government to prevent the abuses that had characterized surface coal mining in the past. Acid Mine Drainage Regulating Coal Mining to Prevent Environmental Problems
Mine Tailings The Law provides authority to regulate active coal mining and fund reclamation of abandoned mine problems. In addition, Congress recognized that mining could damage unique cultural and natural resources and the Law prohibits mining that would destroy them. The Law also provides citizens with special responsibilities in carrying out the enforcement. Regulating Coal Mining to Prevent Environmental Problems
What is Acid Mine Drainage? • AMD results when the mineral pyrite (FeS2) is exposed to air and water, resulting in the formation of sulfuric acid and iron hydroxide FeS2 + O2 + H2O Fe(OH)3 + H2SO4 • Pyrite is commonly present in coal seams and in the rock layers overlying coal seams. AMD formation occurs during surface mining when the overlying rocks are broken and removed to get to the coal. It can also occur in deep mines which allow the entry of oxygen to pyrite-bearing coal seams
What is Acid Mine Drainage? • The products of AMD formation, acidity and iron, can devastate water resources by lowering the pH and coating stream bottoms with iron hydroxide, forming the familiar orange colored “yellow boy” common in areas with AMD. • Many areas also naturally occurring limestone (CaCO3) deposits which neutralizes acidity. • The Department of Environmental Protection (DEP) cannot issue a permit for new coal mining where it is determined mining will cause acid mine drainage.
Acid Mine Drainage Yellow boy in a stream receiving acid drainage from surface coal mining.
In addition to regulating active mines the Surface Mining Law provides funding to reclaim mines abandoned before passage of the Law. Funding for this reclamation program comes from a tax paid by active mine operators on each ton of coal mined. Since there are so many abandoned mine problems, those that pose a danger to the health and safety of people are given the highest priority for reclamation.The photo below shows a very dangerous abandoned mine opening. Reclaiming Mined Areas
