The present study was undertaken to evaluate the impact of flooding of the Solbec-Cupra
oxidized mine tailings on the production of acid mine drainage (AMD). Representative oxidized and
unoxidized mine tailings samples were collected on the site and used in experimental columns and
reservoirs (large lysimeters) to simulate artificial flooding during a minimal period of nine months. The
objectives of this research projet was to verify the efficiency of flooding on the viability and oxidative
activity of microorganisms producing AMD and also to obtain data on the efficiency of the incorporation
of lime into the tailings.
We obtained the following results:
- Flooding of unoxidized tailings prevented their colonization by known iron-oxidizers such
as Tlaiobacillus ferrooxidans and Leptospirillum ferrooxidans mainly because of the neutral pH water.
We did not isolate any of the sulfide oxidizing bacterial strains from the already installed experimental
large lysimeters on the Solbec-Cupra tailings site; however, the oxidized tailings yielded numerous and
varied acidophihc and acidifying bacterial species. - Artificial flooding of unoxidized tailings mixed with netralizing lime material caused the
inhibition of inoculated bacteria as well as their oxidative properties towards pyrite in columns without
eliminating them; their overall viability was preserved during the entire experimentation period. - Lime application was estimated to be 118 tonskectare to a depth of 15 cm, this rate of
application was found to neutralize most of the accumulated acididity in the oxidized tailings, it also
prevented the iron and calcium migration. A security factor, to be determined, could be used to maintain
the pH at an acceptable level on a long term basis. Liming material could be added directiy to water if reacidification
was to occur after flooding. - The existing methods to asses lime dosage in soils are not adequate to predict neutralizing
material needed in mine tailings, mainly because they do not have any buffering capacity.
