Acid Producing Metalliferous Waste Reclamation by Material Reprocessing and Vegetative Stabilization
Goal: This project will attempt to demonstrate an alternative, cost-effective, permanent mine tailing reclamation methodology through the marriage of mineral processing and land reclamation techniques. The approach to be used, Clean Tailing Reclamation (CTR), utilizes potentially field deployable mineral separation technologies to remove dense sulfide minerals from tailing material by gravimetric separation, followed by vegetative stabilization of the cleaned tailing material with native plants. CTR will allow for removal of environmental contaminants and acid-forming materials.
Rationale: Mine waste is a widespread and pervasive problem in EPA Regions VII and VIII. Historical mining activity has contaminated many thousands of acres of soil by uncontrolled waste disposal practices resulting in resource degradation that will cost billions of dollars to remediate. One of the principal problems associated with reclamation of hardrock mine sites is tailing reclamation. Tailing materials cover tens of thousands of acres of land in the region pair. This research specifically compliments research being conducted in Anaconda, Montana, on tailing reclamation and will provide comparisons on the relative strength of this technology, through plant performance, geochemical distribution of contaminants, and cost of implementation. Upon completion of this research, the findings will be useful to Superfund Managers and Potentially Responsible Party decision makers and to operational mines and regulators.
Approach: Research will be implemented at Montana State University. Outside expertise will be solicited from other experts in mineral separation in conjunction with the use of experimental equipment housed at Butte, Montana. Contract laboratories will be solicited and appropriate sample analyses will be submitted for analysis. Sample material used in research will be collected from three locations in coordination with regulatory personnel. Representative samples of tailings materials will be collected from each of the three locations and chemically characterized to identify the elemental and mineralogical distribution of the heavy metal and acid generating contaminants. Subsequent to sample characterization, mineralogical separation of the dense sulfide minerals will be performed using gravimetric techniques. For bench-scale work, mineral separation technologies considered will include technologies developed through the Superfund Innovative Technology Evaluation (SITE) Program. Following tailing material reprocessing activity, subsamples will be chemically characterized to determine the efficacy of the reprocessing/tailing cleaning technologies. Greenhouse studies will be implemented in the cleaned tailing material to compare performance of the cleaned tailing material with conventional reclamation approaches. The native grass species selected for use are Red top (Agrostis alba) and Basin wildrye (Leymus cinereus).
Status: This project is in the information gathering phase. Individuals who have equipment of sufficient capacity to separate large quantities of waste which will be necessary for field studies have been located. One of these will be contracted to carry out physical separation of the tailings prior to implementation of the field amendment and seeding. This project is in its first year.
Clients/Users: This research will be of interest to those in the mining industry and regulatory agencies.