The Hibbing Taconite Company operates an iron mine and mill in northern
Minnesota, USA The tailings produced by the mine are disposed in a tailings basin. The
point of feed is the upstream end of one of the sub-basins within the tailings pond, the
West Area #1. The tailings deposit forms an aggrading alluvial fan within each sub-basin.
Projections of tailings deposition rates within the West Area # 1 indicate an
imminent over-filling at the upper end of the basin. This premature filling, which threatens
to reduce the lifetime of the tailings pond below design expectations, is the result of slopes
in the upper part of the deposit which are steeper than anticipated at the time of basin
design. st. Anthony Falls Laboratory, University of Minnesota, under contract from Barr
Engineering, has undertaken a combined field, experimental, and theoretical study of the
dynamics of tailings-basin sedimentation, with a particular focus on the physical controls
(i.e., water discharge, sediment load, and sediment size distribution) on upper fan slope.
This study has provided the tools necessary to evaluate the relative effectiveness of several
tailings management schemes intended to alleviate the problem.
The tools were developed in two stages. In Stage 1, the analysis was restricted to
West Area #1 due to the availability of specific data pertaining to that area. The results
for Stage 1 were based on the assumption that all future tailings would be stored in West
Area #1. The assumption was made for illustrative purposes only. The results of the
calculation allow, however, for inferences concerning the performance of the entire pond.
In Stage 2, a numerical model was developed to describe filling of the entire basin. The
model allows for the testing of a variety of schemes for tailings management.
Whipple, Kelin X.; Parker, Gary; Paola, Chris; Mohrig, David.
Dynamic Tailings Basin Study: Final Report.
St. Anthony Falls Laboratory.
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