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 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 ...

systems are included. Without these systems the mine will get flooded by water that naturally occurs in rock formations in the ground.

Overview

Mining 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. The exploitation of these deposits for raw material is based on the economic via ...

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. After the mine is closed, when its operational life ends, the maintenance systems stop, including the

systems. Without

, the mines tend to flood with

surface A surface, as the term is most generally used, is the outermost or uppermost layer of a physical object or space. It is the portion or region of the object that can first be perceived by an observer using the senses of sight and touch, and is t ...

and groundwaters in the lower levels and mined spaces, if there is not a drainage adit present. The flooding process of an

open-pit Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique of extracting rock (geology), rock or minerals from the earth from an open-air pit, sometimes known as a Borrow pit, b ...

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.Wolkersdorfer, C., 2008: Water Management at Abandoned Flooded Underground Mines – Fundamentals, Tracer Tests, Modelling, Water Treatment, 465 pp.

Open pit mines

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 Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when th ...

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.

Underground mines

Flooding in underground mines is usually controlled. 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 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. Acid rock drainage occurs naturally within some environments as part of the rock weathering ...

. 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: * Removal of potential water hazards * Fill the surfaces that might collapse during or after the flooding process * Install water diversion systems * Install, at both the surface and underground, a system to monitor hydrogeological and geotechnical aspects * Make a projection of hydrological and hydrogeochemical development of mine waters

Reasons for mine flooding

There are a wide range of factors that leads to mine flooding. Six of those main reasons are: * The mine ceases to be economically important * Depletion of

raw materials A raw material, also known as a feedstock, unprocessed material, or primary commodity, is a basic material that is used to produce goods, finished goods, energy, or intermediate materials that are feedstock for future finished products. As feedst ...

* Political reasons, war or accidents * Instability of the mine workings * Prevention of

disulfide In biochemistry, a disulfide (or disulphide in British English) refers to a functional group with the structure . The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In ...

oxidation * Safety reasons In some locations, flooded mines have been converted into

pumped-storage hydroelectric Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of gravitational potential ...

reservoirs.

Historical mine flooding disasters

* Chasnala mine * Quecreek Mine * Wangjialing mine * Knox Mine *

Milford Mine The Milford Mine produced high manganese-content iron ore in Wolford Township, Minnesota, United States. On February 5, 1924, it was the site of the Milford Mine Disaster, the worst mining accident in Minnesota history, when it was flooded by wa ...

* Luotuoshan mine * Jiangjiawan Mine{{Cite web , url=http://www.mining-technology.com/news/newschinas-jiangjiawan-coal-mine-flood-kills-16-miners-4559642 , title=China's Jiangjiawan coal mine flood kills 16 miners , date=21 April 2015 , access-date=18 March 2022

References

Mining