Mine waste is primarily broken or ground rock with little to no organic matter or nutrients. The Division of Lands and Minerals has studied the use of waste products to improve vegetation in reclamation of taconite tailings. These materials have included various types of compost, residue from paper mills, treated solids from wastewater treatment plants (biosolids) and dredge material from Lake Superior. Based on this research, new reclamation procedures have been developed to successfully reclaim coarse taconite tailings.
Mitigation techniques include methods to prevent mine drainage problems as well as treatment methods for water impacted by mining operations. Methods to prevent mine drainage problems include under water disposal of waste rock and tailings, creating wetlands over tailings, co-disposal of tailings and waste rock, adding alkaline materials to mine waste, and coating reactive surfaces to prevent reaction (microencapsulation).
Treatment can include the use of standard water treatment technologies (active treatment) or newer, lower maintenance options that use natural processes (passive treatment). Minnesota Department of Natural Resources, Division of Lands and Minerals designed a small active treatment plant that treats water from the Hibbing field research site while minimizing operation and maintenance.
The Division of Lands and Minerals has also studied passive systems including wetland treatment, sulfate reducing bioreactors, alkaline treatment beds and the use of covers and liners to control the quantity of water entering or leaving mine waste facilities.
Please see the Reclamation Sections' list of publications (PDF, 249 kb) for more information on the research we have done.