Dennis R. Neuman and Stuart R. Jennings*

ABSTRACT

Reprocessing of metal mine tailings was evaluated as an innovative reclamation technology for sulfide mine wastes. Mine wastes from historic abandoned mines cause resource degradation through oxidation of acid‑forming minerals resulting in the release of metals and acidity to the environment.  Reclamation technologies employed at the present time for sulfide tailing materials typically employ isolation via repositories or chemical treatment for control of acid generation.  Pyrite and other sulfides are not removed during treatment. The long‑term permanence of these isolation and treatment technologies is therefore unknown, since sulfides may be exposed through deterioration of engineered caps or when amendments added during in‑situ treatment are consumed or eroded. In replicated laboratory and greenhouse evaluations of Clean Tailing Technology, sulfides were removed from tailings by reprocessing to create a more hospitable plant rooting media. Tailing reprocessing resulted in decreased total and water soluble metal levels in the cleaned tailing material. Vegetation establishment in the cleaned tailing media relative to growth in topsoil and lime amended tailings was measured and favorably demonstrates the potential for plant establishment and cost savings using Clean Tailing Technology. A field demonstration of tailing reprocessing was performed in which approximately 4000 tons of sulfide mine tailings were reprocessed, amended and seeded.  Transplants of mycorrhizal inoculated species were also included in the revegetation design.  The cleaned tailing test plots were seeded along side a run-of-mine tailing test plot and an alluvial coversoil test plot to contrast the treatment effectiveness of each.  Good vegetation establishment was observed on all plots where compost was included as an amendment.

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* Reclamation Research Group, LLC. 904 South Black Ave., Bozeman, MT 59715