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A flooded mine is one of the direct results of a mine's closure procedure. When a mine stops operating, its maintenance systems also stop, in which the dewatering systems are included. Without these systems the mine will get flooded by water that naturally occurs in rock formations in the ground.
Mining operations can occur over a long period of time, from several years to several decades, and in order to keep the mining operations running, water has to be removed from the mine as it accumulates. [1] After the mine is closed, when its operational life ends, the maintenance systems stop, including the dewatering systems. Without dewatering, the mines tend to flood with surface and groundwaters in the lower levels and mined spaces, if there is not a drainage adit present. The flooding process of an open-pit or underground mine can take from a several months period to more than a decade, depending on factors such as volume of open space in the mine, availability of infiltration water and on the nature of flooding - it can be uncontrolled, controlled or monitored. [2]
Flooding in open pit mines leads to the so-called pit lakes, where a wide range of creatures can be seen. The flooding process happens because the drainage wells or dewatering pumps are stopped and the open spaces are filled with groundwater and surface runoff from precipitation and water bodies (e.g. rivers). Waters quality in flooded open pit mines can range from drinking water quality to acidic waters that can kill animals if drunk.
Flooding in underground mines is usually controlled.[ citation needed ] These types of mines are not directly influenced by surface waters, so it is mainly underground water that plays a role in the flooding. One of the main reasons to let an underground mine be flooded is to avoid disulfide oxidation, and thus avoid acid mine drainage.[ citation needed ] Other important reason is safety: people coming to underground mines without safety precautions or the presence of dangerous mine gases.
The controlled flooding of underground mines usually follows these guidelines:[ citation needed ]
There are a wide range of factors that lead to mine flooding. Six of those main reasons are: [2]
In some locations, there are discussions to use flooded mines for pumped-storage hydroelectric reservoirs, [3] but finished projects are still missing.
A quarry is a type of open-pit mine in which dimension stone, rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some jurisdictions to manage their safety risks and reduce their environmental impact.
Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique that extracts rock or minerals from the earth.
An adit or stulm is a horizontal or nearly horizontal passage to an underground mine. Miners can use adits for access, drainage, ventilation, and extracting minerals at the lowest convenient level. Adits are also used to explore for mineral veins. Although most strongly associated with mining, the term adit is sometimes also used in the context of underground excavation for non-mining purposes; for example, to refer to smaller underground passageways excavated for underground metro systems, to provide pedestrian access to stations, and for access required during construction.
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology.
In mining, tailings or tails are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Tailings are different 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.
The Berkeley Pit is a former open pit copper mine in the western United States, located in Butte, Montana. It is one mile (1.6 km) long by one-half mile (800 m) wide, with an approximate maximum depth of 1,780 feet (540 m). It is filled to a depth of about 900 feet (270 m) with water that is acidic, about the acidity of beer or tomatoes. As a result, the pit's water is laden with heavy metals and dissolved metals that leach from the rock in a natural process known as acid rock drainage. The dissolved metals include but are not limited to copper, arsenic, cadmium, zinc, and sulfuric acid.
Acid mine drainage, acid and metalliferous drainage (AMD), or acid rock drainage (ARD) is the outflow of acidic water from metal mines and coal mines.
The Ranger Uranium Mine was a uranium mine in the Northern Territory of Australia. The site is surrounded by, but separate from Kakadu National Park, 230 km east of Darwin. The orebody was discovered in late 1969, and the mine commenced operation in 1980, reaching full production of uranium oxide in 1981 and ceased stockpile processing on 8 January 2021. Mining activities had ceased in 2012. It was owned and operated by Energy Resources of Australia (ERA), a public company 86.33% owned by Rio Tinto Group, the remainder held by the public. Uranium mined at Ranger was sold for use in nuclear power stations in Japan, South Korea, China, UK, France, Germany, Spain, Sweden and the United States.
Surface mining, including strip mining, open-pit mining and mountaintop removal mining, is a broad category of mining in which soil and rock overlying the mineral deposit are removed, in contrast to underground mining, in which the overlying rock is left in place, and the mineral is removed through shafts or tunnels.
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.
Wheal Jane is a disused tin mine near Baldhu and Chacewater in West Cornwall, England, United Kingdom. The area itself consisted of a large number of mines.
In-situ leaching (ISL), also called in-situ recovery (ISR) or solution mining, is a mining process used to recover minerals such as copper and uranium through boreholes drilled into a deposit, in situ. In-situ leach works by artificially dissolving minerals occurring naturally in the solid state.
The health and environmental impact of the coal industry includes issues such as land use, waste management, water and air pollution, caused by the coal mining, processing and the use of its products. In addition to atmospheric pollution, coal burning produces hundreds of millions of tons of solid waste products annually, including fly ash, bottom ash, and flue-gas desulfurization sludge, that contain mercury, uranium, thorium, arsenic, and other heavy metals. Coal is the largest contributor to the human-made increase of carbon dioxide in Earth's atmosphere.
Dewatering is the removal of water from a location. This may be done by wet classification, centrifugation, filtration, or similar solid-liquid separation processes, such as removal of residual liquid from a filter cake by a filter press as part of various industrial processes.
Cortez Gold Mine is a large gold mining and processing facility in Lander and Eureka County, Nevada, United States, located approximately 63 miles (100 km) southwest of Elko. It is owned as a joint venture between Barrick Gold Corporation (61.5%) and Newmont Corporation (38.5%), operated by Barrick, and comprises the Pipeline, Crossroads, and Cortez Hills open pit mines; and the Cortez Hills underground mine. Ore from the mines is treated at an oxide mill at the site and on leach pads, while refractory ore is shipped to Barrick’s Goldstrike operation for processing.
Environmental impact of mining can occur at local, regional, and global scales through direct and indirect mining practices. Mining can cause erosion, sinkholes, loss of biodiversity, or the contamination of soil, groundwater, and surface water by chemicals emitted from mining processes. These processes also affect the atmosphere through carbon emissions which contributes to climate change.
Black Creek is a tributary of the Susquehanna River in Luzerne County, Pennsylvania, in the United States. It is approximately 2.6 miles (4.2 km) long and flows through Conyngham Township. The creek's watershed has an area of 3.85 square miles (10.0 km2). It is designated as a Coldwater Fishery and a Migratory Fishery. The creek is ephemeral and loses its flow to underground mines. Varying concentrations of many alkali metals, alkaline earth metals, and transition metals occur in water in the creek's watershed. The watershed typically experiences relatively mild temperatures. It is mainly accessible via U.S. Route 11, Pennsylvania Route 239, and a local road.
Mine dewatering is the action of removing groundwater from a mine. When a mine extends below the water table groundwater will, due to gravity, infiltrate the mine working. On some projects groundwater is a minor impediment that can be dealt with on an ad-hoc basis. In other mines, and in other geological settings, dewatering is fundamental to the viability of the mine and may require the use of very large resources and management.
According to a survey completed by the Colorado Geological Survey between 1991 and 1999, the number of abandoned mines in Colorado is 18,382. The Arkansas Headwaters, Las Animas River, Rio Grande Headwaters, Alamosa, and Uncompahgre were the priority watersheds studied in this survey. In the survey, analysis was completed with Environmental Degradation Measures ranging from none to extreme. Results showed 26 abandoned mines with extreme degradation and mineral hazards, 219 with significant degradation, and 672 potentially significant hazards.
The environmental impact of iron ore mining in all its phases from excavation to beneficiation to transportation and beyond may have detrimental effects on air quality, water quality, biological species, and nearby communities. This is predominantly a result of large-scale iron ore tailings that are released into the environment which are harmful to both animals and humans.
