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Summary: PARAMETRIC STUDY ON THE WATER CONTENT PROFILES AND
OXIDATION RATES IN NEARLY SATURATED TAILINGS ABOVE THE
WATER TABLE1
Anne-Marie Dagenais2
, Michel Aubertin, Bruno Bussière
Abstract. A promising concept, known as the elevated water table, is emerging
as a management and possible closure technique to limit AMD production from
tailings impoundments. This prevention approach is based on the principle that
tailings in the capillary zone can be maintained in a state close to full saturation
which minimizes oxygen diffusion and thus limits acid generation. A parametric
study was conducted to evaluate the effect of various factors on the water content
profiles in reactive tailings. The results presented here show that the position of
the water table has a large influence on the water content profiles and on the
oxygen flux at the tailings surface. For a water table depth value smaller or equal
to the tailings' air entry value (a), the degree of saturation Sr varies between 90
to 99 % at the tailings surface, covered by a sand protection layer. These high Sr
values yield effective diffusion coefficient De comparable to that of O2 diffusion
in water. The study also shows that the efficiency of the elevated water table
concept can be negatively affected when the tailings are highly reactive.
Additional Key Words: elevated water table, modeling, water content profiles,
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