ECONOMIC
EVALUATION OF ACID MINE DRAINAGE TECHNOLOGIES
Mine Environment Neutral Drainage at CANMET-MMSL |
MEND Report 5.8.1
January 1995
EXECUTIVE SUMMARY
This report
presents an evaluation of the costs of applying various technologies
to reactive mine wastes in order to prevent, control or treat acid
mine drainage (AMD). The reactive wastes include either tailings
or waste rock which generate, or which may generate in the future,
AMD.
The AMD technologies
selected for the purpose of this study include a composite soil
cover, self-sustained and maintained water covers, some combinations
of these covers, a plastic liner cover, waste removal and the long
term collect and treat option with or without a simple soil (or
vegetation) cover.
The objectives
of this study were to evaluate the costs of currently applied, or
perceived feasible, AMD technologies and their comparison with a
reference to planning future research directions in the AMD area,
and to evaluate the financial liabilities to the Canadian mining
industry and Canadian public as related to reactive mine wastes.
Because the AMD technology costs presented in this report have been
estimated with a specific reference to these two objectives, important
limitations apply to the study results if used for any other purpose.
In essence, these limitations relate to the fact that the cost of
an AMD technology considered for a waste site will depend on numerous
site specific cost factors while the representative AMD technology
costs presented in this report have been estimated with the purpose
of addressing a large number of reactive waste sites.
The study
has been carried out based on actual mine closure projects selected
with a reference to the study objectives. Generic tailings/waste
rock disposal sites have also been considered to address specific
cost issues such as the availability of borrow materials or the
area-volume ratio in the case of a waste rock dump.
In addition
to the direct costs of an AMD technology application, some incidental
costs were also accounted for in the study. The estimated costs
have been compared in terms of their net present values.
The following
representative unit cost ranges have been derived for the two basic
AMD technologies (1994$/ha of tailings footprint or 1994$/tonne
of waste rock):
|
Tailings
|
Waste
Rock
|
Collect
and Treat |
180,000
- 280,000
(210,000)
|
0.4 -
2.0
(0.7)
|
Walk-away
|
100,000
- 300,000
(200,000)
|
1.0 -
1.5
(1.30)
|
where the
values in brackets represent suggested typical ("average")
unit costs.
These unit
costs have been derived with the purpose of identifying AMD technology
costs of practical significance in the sense that the majority of
the actual project costs are expected to fall into one of
the representative cost ranges.
An inventory
of the reactive wastes in Canada was compiled recently by MEND.
Based on this inventory and the representative costs of AMD technology
applications estimated in this study, the financial liabilities
associated with the existing reactive tailings and waste rock in
Canada have been evaluated as follows (in billions of 1994 dollars):
|
Tailings
|
Waste
Rock
|
Possible
Range |
1.8 -
2.9
|
0.4 -
0.9
|
"Average"
Estimate |
2.5
|
0.5
|
The primary
conclusion of the study is that the (unit) costs of AMD technology
applications are very site specific and can vary widely. With a
reference to the considered technologies and study cases, this is
particularly true for the collect and treat option in the case of
waste rock and for the self-sustained water cover option in the
case of tailings.
In general,
the composite soil cover and plastic liner technologies were confirmed
to be the most expensive. From the cost perspective, it seems unlikely
that these technologies would be considered preferable for typical
mine sites. The study results also indicate that it is unlikely
that a walk-away option would be selected for a major waste rock
dump which generates net acidity at the time of closure.
A number of
recommendations with regard to the most desirable future research
directions in the AMD technology area have been developed based
on the study findings and other considerations. Of particular importance
seems to be carrying out a research evaluation of the performance
risks associated with the implementation of various AMD technologies.
The study
results indicate that the self-sustained water cover and the collect
and treat technologies may represent the best options from the perspective
of the implementation costs. Hence, in developing the recommendations
with regard to future AMD research directions, an emphasis was made
on these two technologies.
Français
| Contact Us
| Help | Search
| Canada Site
Home | What's
New | CANMET-MMSL
| MMS Site
| NRCan Site
|