Mine closure

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Mine closure is the period of time when the ore-extracting activities of a mine have ceased, and final decommissioning and mine reclamation are being completed. It is generally associated with reduced employment levels, which can have a significant negative impact on local economies. It is also the period when the majority of mine reclamation is completed, making the land safe and useful again.

Ore rock with valuable metals, minerals and elements

An ore is a natural occurrence of rock or sediment that contains sufficient minerals with economically important elements, typically metals, that can be economically extracted from the deposit. The ores are extracted at a profit from the earth through mining; they are then refined to extract the valuable element or elements.

Mining The extraction of valuable minerals or other geological materials from the earth

Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef or placer deposit. These deposits form a mineralized package that is of economic interest to the miner.

Mine reclamation

Mine reclamation is the process of restoring land that has been mined to a natural or economically usable state. Although the process of mine reclamation occurs once mining is completed, the planning of mine reclamation activities occurs prior to a mine being permitted or started. Mine reclamation creates useful landscapes that meet a variety of goals ranging from the restoration of productive ecosystems to the creation of industrial and municipal resources. In the United States, mine reclamation is a regular part of modern mining practices. Modern mine reclamation minimizes and mitigates the environmental effects of mining.

In South Africa, which is a major mining country, closure planning has not yet been formalized. This has led to a range of unintended consequences [1] that have the potential to become sovereign risk if not adequately managed. [2]

Unintended consequences outcomes that are not the ones intended by a purposeful action

In the social sciences, unintended consequences are outcomes that are not the ones foreseen and intended by a purposeful action. The term was popularised in the twentieth century by American sociologist Robert K. Merton.

Closure planning, a relative newcomer to mine planning, continues throughout the life of a mine, starting with conceptual closure plans prior to production, periodic updates throughout the life of the mine, and a final decommissioning plan. This is captured more coherently in the Australian Model to mine closure. [3] [4]

At most mines, progressive reclamation over the life of the mine is used to reduce the reclamation burden at closure.

Most mine shafts are capped, meaning a large concrete plug around 3 feet thick is placed over the shaft to cover it and stop fatal accidents from occurring. Some mines are capped using large metallic grills, this usual occurs on deep level shafts so airflow through the deep tunnels helps prevent subsidence.

Older mines typically used wood beams, a foot or more thick, under loose rock and dirt as caps. Over time the wood rots and sinkholes can develop. These mines are typically recapped with concrete, steel plates, expanding foam, or a combination of each.

Steel plates are used primarily on horizontal shafts, but are used on vertical shafts occasionally. Doors are added if access is needed. Holes are cut into the plate to allow for drainage as well as for a bat entrance.

Expanding foam is used primarily with vertical shafts where the use of the shaft is no longer desired. It forms a plug 6 feet or more thick. A 4-to-6-inch (100 to 150 mm) pipe through the plug allows for pressure equalization as well as for water drainage, or even as a bat entrance if necessary.

Closure planning has two distinct components. On-site planning is mostly about environmental rehabilitation and returning the landform to a reasonable condition where vegetative recovery is enhanced. Off-mine closure is about loss of livelihood, which is a more complex issue. [5] An element of this is generating an offset against the high clost of environmental remediation, which in certain cases can exceed the value of the mineral that was mined in the first place. [6]

Environmental remediation deals with the removal of pollution or contaminants from environmental media such as soil, groundwater, sediment, or surface water. This would mean that once requested by the government or a land remediation authority, immediate action should be taken as this can impact negatively on human health and the environment.

See also

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Underground mining (hard rock) underground mining techniques used to excavate hard minerals

Underground hard rock mining refers to various underground mining techniques used to excavate hard minerals, usually those containing metals such as ore containing gold, silver, iron, copper, zinc, nickel, tin and lead, but also involves using the same techniques for excavating ores of gems such as diamonds or rubies. Soft rock mining refers to excavation of softer minerals such as salt, coal, or oil sands.

Open-pit mining surface mining technique of extracting rock or minerals from the earth

Open-pit, open-cast or open cut mining is a surface mining technique of extracting rock or minerals from the earth by their removal from an open pit or borrow.

Adit horizontal entrance shaft to an underground mine

An adit is an entrance to an underground mine which is horizontal or nearly horizontal, by which the mine can be entered, drained of water, ventilated, and minerals extracted at the lowest convenient level. Adits are also used to explore for mineral veins.

Tailings are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Tailings are distinct from overburden, which is the waste rock or other material that overlies an ore or mineral body and is displaced during mining without being processed.

Land rehabilitation

Land rehabilitation is the process of returning the land in a given area to some degree of its former state, after some process has resulted in its damage. Many projects and developments will result in the land becoming degraded, for example mining, farming and forestry.

Acid mine drainage

Acid mine drainage, acid and metalliferous drainage (AMD), or acid rock drainage (ARD) is the outflow of acidic water from metal mines or coal mines.

Mine closure planning involves planning effectively for the after-mining landscape – all activities required before, during, and after the operating life of a mine that are needed to produce an acceptable landscape economically. Closure performance refers to the activities near and after mine closure and how well activities listed in the closure plan are carried out.

Shaft mining mining technique

Shaft mining or shaft sinking is excavating a vertical or near-vertical tunnel from the top down, where there is initially no access to the bottom.

Office of Surface Mining

The Office of Surface Mining Reclamation and Enforcement (OSMRE) is a branch of the United States Department of the Interior. It is the federal agency entrusted with the implementation and enforcement of the Surface Mining Control and Reclamation Act of 1977 (SMCRA), which attached a per-ton fee to all extracted coal in order to fund an interest-accruing trust to be used for reclamation of abandoned mine lands, as well as established a set environmental standards that mines must follow while operating, and achieve when reclaiming mined land, in order to minimize environmental impact. OSMRE has about 500 employees, who work in either the national office in Washington, DC, or of the many regional and field offices(OSM's Three Regions).

Mine exploration is a hobby in which people visit abandoned mines, quarries, and sometimes operational mines. Enthusiasts usually engage in such activities for the purpose of exploration and documentation, sometimes through the use of surveying and photography. In this respect, mine exploration might be considered a type of amateur industrial archaeology. In many ways, however, it is closer to caving, with many participants actively interested in exploring both mines and caves. Mine exploration typically requires equipment such as helmets, head lamps, Wellington boots, and climbing gear.

Headframe structural frame above an underground mine shaft

A headframe is the structural frame above an underground mine shaft.

Climax mine

The Climax mine, located in Climax, Colorado, United States, is a major molybdenum mine in Lake and Summit counties, Colorado. Shipments from the mine began in 1915. At its highest output, the Climax mine was the largest molybdenum mine in the world, and for many years it supplied three-fourths of the world's supply of molybdenum.

Mine caps are typically used to prevent access to old, abandoned mines. People, especially the young, like to explore their surroundings but may not fully understand the dangers inherent within, and surrounding, a mine.

Mining in the Upper Harz

Mining in the Upper Harz region of central Germany was a major industry for several centuries, especially for the production of silver, lead, copper, and, latterly, zinc as well. Great wealth was accumulated from the mining of silver from the 16th to the 19th centuries, as well as from important technical inventions. The centre of the mining industry was the group of seven Upper Harz mining towns of Clausthal, Zellerfeld, Sankt Andreasberg, Wildemann, Grund, Lautenthal und Altenau.

Kayenta Mine

The Kayenta mine is a surface coal mine operated by Peabody Western Coal Company on the Navajo Nation in northern Arizona. About 400 acres are mined and reclaimed each year, providing about 8 million tons of coal annually to the Navajo Generating Station.

Operation Scarlift was a program carried out by the Pennsylvania government in the 1960s and 1970s. Its mission was to repair environmental damage caused by abandoned mine lands, acid mine drainage, and other issues associated with historic mining. The operation began around the time that the Land and Water Conservation and Reclamation Act was passed and became inactive in the 1970s due to a lack of funding. During the operation, a total of $141,000,000 was spent on a variety of tasks, including remedying pollution in hundreds of streams, extinguishing dozens of mine fires, and constructing acid mine drainage treatment plants. Numerous reports on mining-impacted streams were produced during the operation, many of which continue to be used for assessing watersheds.

2015 Gold King Mine waste water spill

The 2015 Gold King Mine waste water spill was an environmental disaster that began at the Gold King Mine near Silverton, Colorado, when Environmental Protection Agency personnel, along with workers for Environmental Restoration LLC, caused the release of toxic waste water into the Animas River watershed. They caused the accident while attempting to drain ponded water near the entrance of the mine on August 5. After the spill, the Silverton Board of Trustees and the San Juan County Commission approved a joint resolution seeking Superfund money.

Abandoned mine drainage water pollution from abandoned mines

Abandoned mine drainage is a form of water pollution involving water that has been polluted by contact with mines, typically coal mines. Although it is sometimes called "acid mine drainage", not all abandoned mine drainage is acidic.

In the mid-19th century, Colorado Springs was a center of mining industry activity. Coal was mined in 50 mines in the area and towns, now annexed to Colorado Springs, were established to support residents of the coal mining industry.

References

  1. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2012-04-25. Retrieved 2011-10-13.CS1 maint: archived copy as title (link)
  2. ↑ Meijerink, Sander (2009). Water Policy Entrepreneurs: A Research Companion to Water Transitions Around the Globe. ISBN   9781849803366.
  3. ↑ http://www.dmp.wa.gov.au/documents/Shed_env_guide_closure.pdf
  4. ↑ "Mine closure australia - Google Search".
  5. ↑ "BHP mine closure devastates West Australian towns".
  6. ↑ Adler, R., Claassen, M., Godfrey, L. & Turton, A.R. 2007. Water, Mining and Waste: A Historical and Economic Perspective on Conflict Management in South Africa. In The Economics of Peace and Security Journal, Vol. 2, No. 2 (2007), Pp 32 – 41.
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