The Environmental Protection Agency, other federal government agencies, States, and Tribes have been managing investigations and cleanup activities at mining and mineral processing sites for over twenty years. A large number of cleanup technological innovations have been successfully utilized in the removal and handling of mining waste .
There are three major categories of technology used for environmental remediation and site remediation projects. These technologies are: Conventional, Innovative/Emerging, and Institutional Controls.
Conventional Treatment Technologies
- Chemical Treatment
In chemical treatment, reagents are used to eliminate or chemically
change organic and inorganic contaminants, changing hazardous constituents into less
environmentally destructive forms.
Stabilization points to steps that lower the hazard posed by a waste by
changing the contaminants into a less soluble, less mobile, and, consequently, less harmful type without always modifying the actual physical nature of the waste.
Solidification pertains to procedures that encapsulate waste in a monolithic solid of
- Thermal Desorption
Thermal desorption pertains to treatment solutions that use high temperatures to
remediate contaminated soils, sediments, and sludges.
- Thermal Destruction
Thermal destruction typically uses higher temperature ranges to actually break down the contaminants, potentially with no hazardous
contaminant residues requiring further management.
- Vapor Extraction
Vapor extraction is an in-situ procedure that uses vacuum technologies and
subsurface retrieval systems to eliminate contamination in its gas-phase.
- Solvent Extraction
Solvent/chemical extraction is an ex-situ separation and concentration
process in which a nonaqueous liquid reagent is used to remove organic and/or inorganic
contaminants from wastes, soils, sediments, sludges, or water.
- Soil Washing
The ex-situ procedure of soil washing uses chemical and physical removal
and detachment techniques to remove a broad range of organic, inorganic, and radioactive contamination from soils.
- Soil Flushing
The in-situ procedure of soil flushing uses water, enhanced water, or gaseous
combinations to increase the mobilization of contaminants from a contaminated soil for recovery and treatment.
- Decontamination of Buildings
Decontamination of buildings and other structures through
various extraction and treatment techniques may be necessary at certain mining and mineral processing sites. Decontamination may be as easy as pressure washing a structure or more complicated, involving partial removal practices.
For this site remediation treatment, you use reagents to destroy or modify the contaminants. This method can be used to neutralize acid rock drainage or to enhance a subsequent process. Lime treatment for acid rock drainage is one of the most common forms of chemical treatment.
Site Remediation by Stabilization
This is changing the contaminants to a less mobile or soluble form thereby making it less hazardous to the environment. For example, stabilization could be used to treat soil pollution found in a sludge slurry by changing the pH of the sludge to make it less mobile. Another form often used for stabilization is the capping of soil pollution. In this case, a clean cap of soil is placed over the polluted soil to protect it from running into streams and rivers.
Solidification of Contaminants
This process involves making the pollution solid, such as capping or mixing the pollution into a concrete block. The contaminant migration is restricted vastly by decreasing the surface area exposed to leaching or runoff from rain or stormwater.
Decontamination of Buildings
When a mine site or industrial operations are complete, there is often a desire to preserve the historical significance of the buildings. When this occurs, the structures themselves will need to be decontaminated. Site remediation by decontamination could be as simple as washing the building or as complicated as removing asbestos from the interior walls and ceilings.
Thermal destruction uses high temperatures in an attempt to decompose the contaminants. For mining, it is generally unsuccessful as the process does not actually destroy the metal.
Note: This page is produced as educational content to assist our clients and engineers in gaining a better understanding of environmental remediation. Portions of the content of this page are summarized and copied from the EPA Abandoned Mine Site Characterization and Cleanup Handbook.