Site Data for Mining Waste Materials
Characterizing Waste Materials at Legacy Mining Mineral Processing Sites
At some Superfund legacy mining and mineral processing sites, waste materials like waste rock, tailings, and mining-influenced water have been characterized to include concentrations of critical minerals. This information can serve as a resource in illustrating the challenges of treating contaminants during site remediation and the opportunities for beneficial use of waste through critical minerals recovery. A brief overview of the site geology and mining history is provided below for a number of sites, along with an overview and more detailed data characterizing the geochemistry of the waste material. For more information, reach out to info@emrtai.org.
Mining-Influenced Water (MIW)
The site is an abandoned hard rock mine where copper, zinc, and some trace gold and silver were recovered from sulfide ore. The sulfide ore body contained the minerals pyrite, chalcopyrite, and sphalerite. At the site, a concrete bulkhead was placed within an adit to control mining-influenced water, and this sample was collected prior to introduction of the MIW to the open atmosphere. SEM was performed on waste rock samples, which were characterized as highly weathered and composed of 40% silicates with notably high iron sulfide content (35%) and with 0.8% chalcopyrite.
Solid Waste Materials
Undisclosed Site - Southwest Colorado
Solid Waste Materials
Tailings pond and waste rock dump from an undisclosed site in southwest Colorado. Mining in the area was focused on gold, silver, copper, lead, and zinc deposits. SEM was used to characterize tailings mineralogy, which were characterized as Silicate-rich tailings with a quartz-K-feldspar-plagioclase assemblage and approximately 1% sulphides.
Mining-Influenced Water (MIW)
MIW at this site is discharged from a mine adit. Historical mining in this area focused on silver, lead, and zinc deposits.
Mining-Influenced Water (MIW)
The Berkeley Pit is within Operational Unit 3 and is a former open pit zinc and copper mine that is located in Butte, Montana. The pit became flooded with groundwater after the cessation of mining and associated dewatering in the 1980s. Additional information on surface water geochemistry and the chemical composition of sludge from the onsite Horseshoe Bend Water Treatment Plant can be found in Montana Bureau of Mines and Geology Open_file Report 769, published in January 2025. Read the full report.
Mining-Influenced Water (MIW)
Iron Mountain Mine (IMM) is located in the Klamath Mountains in Shasta County, California. For approximately a decade (1860s to about 1963), the site was periodically mined for silver, gold, copper, zinc, and sulfide-containing minerals. Acid mine drainage (AMD) is collected from three mine portals and a fourth location before onsite treatment. A large lime neutralization plant has been treating the AMD since 1994. The plant was converted to a high density sludge (HDS) process in 1997 and expanded to its current design capacity of 6,500 gpm in 2001. MIW samples can be obtained from the three portals and from the combined influent to the treatment plant. Waste rock is present at the site in rock dumps. SEM was used to characterize the mineralogy of waste rock, which is highly weathered and composed of approximatey 50% iron oxide by mass. Quartz content exceeds 30% with 3% sulfides.
EPA Region 9 is interested in supporting evaluations of technologies to recover critical minerals, rare earth elements, or other economically valuable constituents of the aqueous and solid wastes generated at the IMM Superfund site. Funding may be available to support bench-scale and pilot scale testing of promising technologies.
Waste Rock
Treatment Solids
Solid Waste Materials
Historical mining at the Tar Creek Site was focused on the massive sulfide lead and zinc deposits of galena and sphalerite associated with the ore deposit. The sulfide ore body is also known to contain significant quantities of barium, cadmium, copper and, germanium. Samples were collected to characterize one of the larger chat piles and several areas that contain washed fines. SEM analyses were conducted to characterize mineralogy, and the silicate-rich tailings and washed fines are composed of 80-90% quartz. Spalerite and zinc silicates content range from 1-2%.
