Mine reclamation
Encyclopedia
Mine reclamation is the process of creating useful landscape
s that meet a variety of goals, typically creating productive ecosystems (or sometimes industrial or municipal land) from mined land. It includes all aspects of this work, including material placement, stabilizing, capping, regrading
, placing cover soil
s, revegetation
, and maintenance.
Modern mine rehabilitation aims to minimize and mitigate the environmental effects of modern mining, which may in the case of open pit mining involve movement of significant volumes of rock. Rehabilitation management is an ongoing process, often resulting in open pit mines being backfilled.
After mining finishes, the mine area must undergo rehabilitation.
For underground mines, rehabilitation is not always a significant problem or cost. This is because of the higher grade of the ore
and lower volumes of waste rock and tailings. In some situations, stope
s are backfilled with concrete
slurry
using waste, so that minimal waste is left at surface.
The removal of plant
and infrastructure
is not always part of a rehabilitation program, as many old mine plants have cultural heritage
and cultural value. Often in gold
mines, rehabilitation is performed by scavenger operations which treat the soil within the plant area for spilled gold using modified placer mining
gravity collection plants.
In the United States
, mine reclamation is a regular part of modern mining practice.
Landscape
Landscape comprises the visible features of an area of land, including the physical elements of landforms such as mountains, hills, water bodies such as rivers, lakes, ponds and the sea, living elements of land cover including indigenous vegetation, human elements including different forms of...
s that meet a variety of goals, typically creating productive ecosystems (or sometimes industrial or municipal land) from mined land. It includes all aspects of this work, including material placement, stabilizing, capping, regrading
Regrading
Regrading is the process of raising and/or lowering the levels of land; such a project can also be referred to as a regrade. Regrading may be done on a small scale or on quite a large scale...
, placing cover soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
s, revegetation
Revegetation
Revegetation is the process of replanting and rebuilding the soil of disturbed land. This may be a natural process produced by plant colonization and succession, or an artificial , accelerated process designed to repair damage to a landscape due to wildfire, mining, flood, or other cause...
, and maintenance.
Modern mine rehabilitation aims to minimize and mitigate the environmental effects of modern mining, which may in the case of open pit mining involve movement of significant volumes of rock. Rehabilitation management is an ongoing process, often resulting in open pit mines being backfilled.
After mining finishes, the mine area must undergo rehabilitation.
- Waste dumps are contoured to flatten them out, to further stabilize them against erosionErosionErosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
. - If the ore contains sulfides it is usually covered with a layer of clayClayClay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
to prevent access of rainRainRain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...
and oxygenOxygenOxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
from the air, which can oxidize the sulfides to produce sulfuric acidSulfuric acidSulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
. - LandfillLandfillA landfill site , is a site for the disposal of waste materials by burial and is the oldest form of waste treatment...
s are covered with topsoilTopsoilTopsoil is the upper, outermost layer of soil, usually the top to . It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs.-Importance:...
, and vegetationVegetationVegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader...
is planted to help consolidate the material. - Dumps are usually fenced off to prevent livestockLivestockLivestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...
denuding them of vegetation. - The open pit is then surrounded with a fence, to prevent access, and it generally eventually fills up with groundwaterGroundwaterGroundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. 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...
. - TailingsTailingsTailings, also called mine dumps, slimes, tails, leach residue, or slickens, are the materials left over after the process of separating the valuable fraction from the uneconomic fraction of an ore...
damDamA dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
s are left to evaporate, then covered with waste rock, clay if need be, and soilSoilSoil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
, which is planted to stabilize it.
For underground mines, rehabilitation is not always a significant problem or cost. This is because of the higher grade of the ore
Ore
An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....
and lower volumes of waste rock and tailings. In some situations, stope
Stoping (mining method)
Stoping is the removal of the wanted ore from an underground mine leaving behind an open space known as a stope. Stoping is used when the country rock is sufficiently strong not to cave into the stope, although in most cases artificial support is also provided...
s are backfilled with concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
slurry
Slurry
A slurry is, in general, a thick suspension of solids in a liquid.-Examples of slurries:Examples of slurries include:* Lahars* A mixture of water and cement to form concrete* A mixture of water, gelling agent, and oxidizers used as an explosive...
using waste, so that minimal waste is left at surface.
The removal of plant
Physical plant
Physical plant or mechanical plant refers to the necessary infrastructure used in support and maintenance of a given facility. The operation of these facilities, or the department of an organization which does so, is called "plant operations" or facility management...
and infrastructure
Infrastructure
Infrastructure is basic physical and organizational structures needed for the operation of a society or enterprise, or the services and facilities necessary for an economy to function...
is not always part of a rehabilitation program, as many old mine plants have cultural heritage
Cultural heritage
Cultural heritage is the legacy of physical artifacts and intangible attributes of a group or society that are inherited from past generations, maintained in the present and bestowed for the benefit of future generations...
and cultural value. Often in gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
mines, rehabilitation is performed by scavenger operations which treat the soil within the plant area for spilled gold using modified placer mining
Placer mining
Placer mining is the mining of alluvial deposits for minerals. This may be done by open-pit or by various surface excavating equipment or tunneling equipment....
gravity collection plants.
In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, mine reclamation is a regular part of modern mining practice.
See also
- Surface Mining Control and Reclamation Act of 1977Surface Mining Control and Reclamation Act of 1977The Surface Mining Control and Reclamation Act of 1977 is the primary federal law that regulates the environmental effects of coal mining in the United States....
- Land rehabilitationLand rehabilitationLand 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...
- Mine closure planningMine closure planningMine 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...