At present, the drilling and blasting required for overburden fragmentation is the major limitation on increased surface mining productivity, and the development of improved rock fragmentation practices is an essential requirement for increased surface mine production.
For underground mining, the increased use of longwall mining see Appendix E offers the greatest potential for higher productivity. While deeper reserves will be ideal for the increased application of longwalls, a number of limitations to the current production potential of longwalls, in particular the need for better roof support and improved coal haulage systems, must be overcome. Other areas in which the development of advanced technologies offers considerable potential for increased productivity are the continuous monitoring of produced coal and the development of improved remote control, automatic control, and autonomous systems.
Selective mining and blending are two practices that have been advocated to decrease the handling of unnecessary waste during mining and processing, and to increase the utilization of all coals for a range of purposes. While the bulk. Even when exploration shows promise of an economically minable deposit, the elapsed time from first investment in planning until a mine enters full production, after passing through the permitting, construction, and marketing processes, can take anywhere from seven to fifteen years for a large operation.
Although smaller operations in established coal mining districts may take less time, two to five years is normal even in these situations. This time delay can significantly impact the economic feasibility of opening a new mine and will have to be minimized if the higher production scenarios for the future are to be achieved.
The effect of improved marginal economics by increasing coal recovery can be significant—in one case, a study showed that a 1 percent increase in recovery of coal could increase profits by 25 percent. Also, a considerable amount of surface-mined subbituminous coal is lost because of out-of-seam dilution with mineral matter—an annual loss of as much as 10 million tons was reported for the Arch Coal Black Thunder Mine which produces about 80 million tons per year.
Improved coal processing also offers the potential to minimize existing environmental problems and potential future issues. Many of these piles are environmental liabilities being dealt with under the federal Abandoned Mine Land reclamation program, but a growing number are being viewed as potential opportunities for utilization.
Pennsylvania has 14 sites at which circulating. Improved coal processing also offers potential for responding to future environmental requirements. For example, the development of new or modified flotation processes permit fuel oil to be replaced as a froth flotation collector if it is prohibited because of disposal concerns. There are two technical areas where the development of improved coal processing technologies offers the greatest potential to increase resource recovery Peterson et al.
The use of improved information technology, perhaps in conjunction with improved online analysis capabilities, to optimize the performance and efficiency of existing unit operations; and.
The development and deployment of better materials with which to construct vessels, separation devices, and conduits. The primary needs for research in the broad environmental area are to support the regulation of existing and future mining operations and to mitigate the effects of past mining practices. Existing Mine Operations. There is still an incomplete understanding of how strata behave after coal is extracted from both surface and underground mines, and the hydrologic consequences of mining are not fully understood.
For surface mining, the properties of the altered subsurface—particularly the leaching and permeability characteristics—are likely to be different compared to those existing prior to mining.
For underground mining, the collapse of strata above a coal seam into the mined void can propagate all the way to the surface, damaging buildings and disrupting the quantity and quality of surface and subsurface water flows. Disposal of mine waste can be a significant problem, particularly where the coal has to be cleaned before shipment e.
There is a need for enhanced understanding of the physical and chemical behavior of spoil stored in valleys or waste—from coal combustion or coal preparation plants—that is disposed in surface or underground mines. Waste management is a major problem where land either is not available or is more valuable for other productive uses.
Increased research to develop productive uses of mine waste offers considerable potential to reduce waste disposal issues. Mine Decommissioning and Closure. The major decommissioning and closure activities are 1 sealing of all access to underground mine areas, 2 removal of all surface facilities, and 3 reclamation of surface mine areas generally carried out concurrently with mining operations and the surface areas of underground mines.
Underground and surface coal mines present different challenges for decommissioning and closure. The critical factors in underground mining are the effects of subsidence and hydrology, both of which require continued monitoring and control. For surface mines, the critical factors relate to drainage and treatment of water and to erosion and sedimentation of the slopes, the waste and spoil banks, and the final pit. Continued use of the surface mine infrastructure e.
A mining plan that is well integrated with a community master plan can result in optimum post-mining use of this infrastructure. Abandoned Mined Lands. A range of environmental issues e. This problem is particularly acute in the older coal mining districts of the eastern United States, specifically in the Appalachian hill country. Although mine closure today is a rigorously regulated process requiring detailed technical and financial analysis during the planning and operation stages for a mine—and ensuring financial and legal responsibility for post-mining closure—the nation continues to grapple with the effects of past mining practices.
Additional research is required to develop and demonstrate more effective and sustainable solutions to the problems of acid mine drainage, mine fires, and the utilization of waste piles from AML sites. In general, the scope of and motivation for research are determined by the relevance and potential impact of the problems that need to be dealt with by these various stakeholders. Industry participants in mining research include individual companies and mining company associations.
While the federal government continues to have extensive involvement in the regulation of the coal mining industry, its support for mining research has decreased substantially over the past 10 years. At present, federal research is focused primarily on health and safety. Some research is being done on environmental issues, but support for research aimed at advanced mining technologies. Engineering and Technology Development.
Although not exclusively focused on extraction or on coal mining, many of the program outputs were applicable to the extraction phase of the coal fuel cycle. Relatively little is being done by the federal government to address coal preparation issues.
DOE-FE had a solid fuels program, although it tended to fund more advanced work—such as chemical coal cleaning—than processes related to conventional coal preparation. However, there has been no administration request for funding for this area in recent years, and the program is essentially defunct. Some research programs addressing a variety of mineral separation issues i.
There is a low level of support for fundamental research in the earth sciences and engineering disciplines geosciences, material sciences, rock mechanics, etc. Health and Safety. The NIOSH Mining Program has seven areas of health and safety research activity, addressing respiratory diseases, hearing loss, cumulative musculoskeletal injuries, traumatic injuries, disaster prevention, rock safety engineering, and surveillance and training.
Reclamation and Rehabilitation of Abandoned Mined Lands. Among the stated purposes of SMCRA were to support research, training programs, and the establishment of research and training centers in the states on various aspects of mineral production.
Although the involvement of OSM with aspects of extraction research is minimal, OSM does have limited technical and applied science activities in support of its regulatory mission. In particular, OSM, in cooperation with the states, plays a major role with regard to the reclamation and rehabilitation of abandoned mined lands. The environmental problems associated with active and abandoned mines and their abatement, particularly land reclamation and water quality maintenance, and the proper handling and disposal of the spoils and wastes from mining operations e.
Environmental Protection Agency. EPA is also involved in a program to promote the capture and utilization of coal bed methane. Overall, coal mining research in EPA is limited to support for its regulatory role. Mining Regulation. The Mine Safety and Health Administration, in the Department of Labor, provides technical support and training services to its personnel and to personnel from the mining industry through its Pittsburgh Safety and Health Technology Center and the National Mine Health and Safety Academy.
The direct involvement of MSHA in funding mining research is limited because of its primary regulatory role. However, MSHA undertakes field investigations, laboratory studies, and cooperative research activities on health and safety issues in support of its inspection and technical support functions.
It also supports state miner training activities through its state grants program. State government involvement in coal mining and processing research is primarily dependent on the importance of the mining industry to each particular state. The major coal-producing states—Wyoming, West Virginia, Kentucky, Pennsylvania, Texas, Virginia, and Illinois—have or have had agencies with specific responsibilities for health, safety, and environmental issues associated with coal mining.
Further, mining industry organizations in these states work closely with state agencies to support research programs that address the specific needs of coal reserve estimation and coal mining operations.
Some state governments have provided grants for coal processing research in academic departments e. The mining industry is truly international—not only are mining operations carried out globally, but there is considerable capital, knowledge, and mined-materials flow across international boundaries to satisfy the global demand for mined and processed materials.
The coal industries in different countries have much in common, particularly with regard to health, safety, and environmental issues. Because of these similarities, there is considerable exchange of research results—developments in one country are quickly incorporated into mining practices in other countries. This global interaction is particularly facilitated by mining equipment manufacturers.
The consolidation of coal mining equipment manufacturers over the past three decades and the broad applicability of equipment across a range of mining situations have led manufacturers to work with mining clients and their own suppliers to develop evolutionary improvements to their products. In addition, equipment manufacturers invest substantial resources to improve the durability and reliability of mining equipment. Some equipment manufacturers have worked in partnership with government agencies and mining companies to develop and demonstrate new concepts e.
For some equipment manufacturers, mining equipment is only one of many product lines. The applied engineering research and development work that they conduct is generally fundamental to their production and materials processes, and the research is often proprietary and not generally available to the wider industry. Cross-industry research under the aegis of coal companies or coal industry organizations, or with support from industry organizations, appears to be minimal.
There are no longer organizations such as Bituminous Coal Research, Inc. BCR that used to work on coal mining and coal preparation issues. Several coal companies work in partnership with government agencies and academic institutions on coal mining research projects.
The importance to researchers of access to operating mines and input from mining company experts is particularly worth noting. The funds are paid to Australian Coal Research Ltd. ACR , a company established by the industry to manage all aspects of the program. The research projects, which are conducted by university, industrial, and government-affiliated researchers, are monitored by industry representatives.
Under this agreement, the government agrees to provide a certain level of funding each year to the CRC, and CRC participants agree to undertake certain activities and contribute specified personnel and resources. This recognized the importance of developing research priorities for new technologies and joint sponsorships of chosen projects, and resulted in an NMA-DOE partnership that supported several roadmaps as part of the Mining IOF program.
The more difficult mining conditions that will be encountered in the future will require improved methods to protect the health and safety of mine work-. A range of factors increase health and safety risks to the coal mining workforce, including the introduction of new equipment and systems; the commencement of mining in virgin areas; the infusion of new workers; and the mining of multiple seams, seams that are thinner, thicker, or deeper than those customarily mined at present and new seams that underlie or overlie previously mined-out seams.
All of these factors are likely to apply to some degree in future mines, irrespective of whether the higher production scenarios suggested in some forecasts eventuate. If they do materialize, then these risks are likely to become even more pronounced.
There are major knowledge gaps and technology needs in the areas of survival, escape, communications systems both surface-to-underground and underground-to-underground , and emergency preparedness and rescue. Additional risk factors that are likely to apply in the deeper mines of the future are the potential hazards related to methane control, dust control, ignition sources, fires, and explosions.
Greater understanding and better prediction of strata behavior to prevent unanticipated 12 roof collapse, particularly problems associated with roof and side fall during thick seam extraction, are essential for maintaining and improving worker safety. Federal support for health and safety research significantly decreased about a decade ago, and has essentially remained constant since that time.
Recommendation: Health and safety research and development should be expanded to anticipate increased hazards in future coal mines. This should be coupled with improved training of the mining workforce in all aspects of mine safety. Roof collapse is anticipated during longwall mining after the coal has been removed see Appendix E. Most mining health and safety research by the federal government is carried out by the Mining Program at the National Institute for Occupational Safety and Health.
Technology-related activities in the Mine Safety and Health Administration are limited to technical support and training services for its personnel and those from the mining industry.
Coal mining has environmental impacts on air, water, and land. Surface mining can also cause landslide s and subsidence when the ground begins to sink or cave in. Toxic substances leach ing into the air, aquifer s, and water table s may endanger the health of local residents. In the United States, the Surface Mining Control and Reclamation Act of regulates the process of coal mining, and is an effort to limit the harmful effects on the environment.
The act provides funds to help fix these problems and clean up abandoned mining sites. The three main types of surface coal mining are strip mining, open-pit mining, and mountaintop removal MTR mining. Surface Mining: Strip Mining Strip mining is used where coal seams are located very near the surface and can be removed in massive layers, or strips.
Overburden is usually removed with explosives and towed away with some of the largest vehicles ever made. Dump trucks used at strip mines often weigh more than tons and have more than 3, horsepower. Strip mining can be used in both flat and hilly landscapes. Strip mining in a mountainous area is called contour mining. Contour mining follows the ridges, or contours, around a hill.
A pit, sometimes called a borrow, is dug in an area. This pit becomes the open-pit mine , sometimes called a quarry. Open-pit mines can expand to huge dimensions, until the coal deposit has been mined or the cost of transporting the overburden is greater than the investment in the mine. Open-pit mining is usually restricted to flat landscapes. After the mine has been exhausted, the pit is sometimes converted into a landfill.
After the summit is cleared of vegetation, explosives are used to expose the coal seam. After the coal is extracted, the summit is sculpted with overburden from the next mountaintop to be mined.
By law, valuable topsoil is supposed to be saved and replaced after mining is done. Barren land can be replanted with trees and other vegetation. Mountaintop removal began in the s as a cheap alternative to underground mining.
It is now used for extracting coal mainly in the Appalachian Mountains of the U. MTR is probaby the most controversial coal mining technique. The environmental consequences are radical and severe. Waterways are cut off or contaminated by valley fill. Habitats are destroyed. Toxic byproduct s of the mining and explosive processes can drain into local waterways and pollute the air.
Miners travel by elevator down a mine shaft to reach the depths of the mine, and operate heavy machinery that extracts the coal and moves it above ground. The immediate environmental impact of underground mining appears less dramatic than surface mining. There is little overburden, but underground mining operations leave significant tailings.
Tailings are the often-toxic residue left over from the process of separating coal from gangue , or economically unimportant minerals. Toxic coal tailings can pollute local water supplies.
To miners, the dangers of underground mining are serious. Underground explosions, suffocation from lack of oxygen, or exposure to toxic gases are very real threats. To prevent the buildup of gases, methane must be constantly ventilated out of underground mines to keep miners safe.
There are three major types of underground coal mining: longwall mining, room-and-pillar mining, and retreat mining. Underground Mining: Longwall Mining During longwall mining , miners slice off enormous panels of coal that are about 1 meter 3 feet thick, kilometers The panels are moved by conveyor belt back to the surface.
The roof of the mine is maintained by hydraulic supports known as chock s. As the mine advances, the chocks also advance. The area behind the chocks collapses. Longwall mining is one of the oldest methods of mining coal. Before the widespread use of conveyor belts, ponies would descend to the deep, narrow channels and haul the coal back to the surface. Today, almost a third of American coal mines use longwall mining.
Columns pillars of coal support the ceiling and overburden. The rooms are about 9 meters 30 feet wide, and the support pillars can be 30 meters feet wide. There are two types of room-and-pillar mining: conventional and continuous. In conventional mining, explosives and cutting tools are used. In continuous mining, a sophisticated machine called a continuous miner extracts the coal.
In developing countries, room-and-pillar coal mines use the conventional method. Underground Mining: Retreat Mining Retreat mining is a variation of room-and-pillar. When all available coal has been extracted from a room, miners abandon the room, carefully destroy the pillars, and let the ceiling cave in.
Remains of the giant pillars supply even more coal. Retreat mining may be the most dangerous method of mining. A great amount of stress is put on the remaining pillars, and if they are not pulled out in a precise order, they can collapse and trap miners underground. How We Use Coal People all over the world have been using coal to heat their homes and cook their food for thousands of years.
Coal was used in the Roman Empire to heat public baths. In the Aztec Empire, the lustrous rock was used for ornaments as well as fuel. The Industrial Revolution was powered by coal. It was a cheaper alternative than wood fuel, and produced more energy when burned. Coal provided the steam and power needed to mass-produce items, generate electricity, and fuel steamships and trains that were necessary to transport items for trade.
Today, coal continues to be used directly heating and indirectly producing electricity. Coal is also essential to the steel industry. Fuel Around the world, coal is primarily used to produce heat. Coal can be burned by individual households or in enormous industrial furnace s. It produces heat for comfort and stability, as well as heating water for sanitation and health.
Electricity Coal-fired power plants are one of the most popular ways to produce and distribute electricity. In coal-fired power plant s, coal is combusted and heats water in enormous boilers. The boiling water creates steam, which turns a turbine and activates a generator to produce electricity. Poland, China, Australia, and Kazakhstan are other nations that rely on coal for electricity. Coke Coal plays a vital role in the steel industry. In order to produce steel, iron ore must be heated to separate the iron from other minerals in the rock.
In the past, coal itself was used to heat and separate the ore. However, coal releases impurities such as sulfur when it is heated, which can make the resulting metal weak. As early as the 9th century, chemists and engineer s discovered a way to remove these impurities from coal before it was burned. This drives off impurities such as coal gas, carbon monoxide, methane, tars, and oil.
The resulting material—coal with few impurities and high carbon content—is coke. The method is called coking. The hot air ignites the coke, and the coke melts the iron and separates out the impurities. The resulting material is steel. Coke provides heat and chemical properties that gives steel the strength and flexibility needed to build bridges, skyscrapers, airports, and cars. Many of the biggest coal producers in the world the United States, China, Russia, India are also among the biggest steel producers.
Japan, another leader in the steel industry, does not have significant coal reserves. Synthetic Products The gases that are released during the coking process can be used as a source of power.
Coal gas can be used for heat and light. Coal can also be used to produce syngas , a combination of hydrogen and carbon monoxide. Syngas can be used as a transportation fuel similar to petroleum or diesel. In addition, coal and coke byproducts can be used to make synthetic materials such as tar, fertilizers, and plastics.
Coal and Carbon Emissions Burning coal releases gases and particulate s that are harmful to the environment. Carbon dioxide is the primary emission. It is called a greenhouse gas because it absorbs and retains heat in the atmosphere, and keeps our planet at a livable temperature. In the natural carbon cycle , carbon and carbon dioxide are constantly cycled between the land, ocean, atmosphere, and all living and decomposing organisms. Carbon is also sequester ed, or stored underground.
This keeps the carbon cycle in balance. However, when coal and other fossil fuels are extracted and burned, they release sequestered carbon into the atmosphere, which leads to a build-up of greenhouse gases and adversely affects climate s and ecosystems.
Other Toxic Emissions Sulfur dioxide and nitrogen oxides are also released when coal is burned. These contribute to acid rain , smog , and respiratory illness es. Mercury is emitted when coal is burned. In the atmosphere, mercury is usually not a hazard.
In water, however, mercury transforms into methylmercury, which is toxic and can accumulate in fish and organisms that consume fish, including people. Fly ash which floats away with other gases during coal combustion and bottom ash which does not float away are also released when coal is combusted. Depending on the composition of the coal, these particulates can contain toxic elements and irritants such as cadmium, silicon dioxide, arsenic, and calcium oxide.
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