When a taconite mine operation closes and is reclaimed as a permanent mine feature, there can be substantial changes to the natural landscape, including tailings basins and waste rock stockpiles. Weathering of these mine wastes can release sulfate and other constituents of concern to surrounding waters.
LAM environmental research staff perform field-based studies to help characterize the weathering processes occurring at existing minelands in northeastern Minnesota. Recent field investigations focused on quantifying the three key reactants involved in sulfide oxidation (oxygen, water, and sulfide minerals) at shallow depths in a tailings basin. The data from these experiments helps LAM environmental research staff understand the primary hydrologic and geochemical processes related to sulfate release and transport in and around taconite tailings basins on the Iron Range.
Site-specific climate information is also critical for understanding the weathering of mine wastes. Eddy covariance is a sophisticated method that provides a direct measurement of ecosystem evapotranspiration. DNR has recently employed this method to help establish more accurate evaporation and evapotranspiration inputs for mine site water balances.
Core collection at a MN taconite tailing basin
Eddy covariance system deployed at a MN taconite tailings basin
Oxygen sensors at a MN taconite tailing basin
Mine site field studies research documents
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