Environmental Aspects of Phosphate and Potash Mining United ...

Closure
The Environmental Approach of the Phosphate Rock and Potash Mining Industry
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3.7 Mine Closure
Mine closure activities occur on cessation of mining
and beneficiation activities, following the exhaustion
of the ore reserve. The aim focus of mine closure is to
leave the mine site in a stable and safe condition. This
involves:
Finalizing rehabilitation that commenced earlier
in the mine life;
Rehabilitation and other activities such as sealing
shafts and removing plant and equipment that
could not be removed until after mining and beneficiation
were completed;
Monitoring the keep of rehabilitation and closure
activities in the long term;
Rehabilitation is generally conducted progressively
throughout the mine life, as discussed in detail
in the next section;
Social impacts on the workforce and on the community,
associated with the closure of an
operation, may be complex. They are important
but fall outside the scope of the present publication.
Figure 3.7.1
Potential environmental effects : closure
Monitoring
Removal of equipment
and plant, shaft sealing,
stabilisation, monitoring
Ongoing monitoring and management is important
to satisfy local communities, government agencies
and other stakeholders, that the agreed post-mining
land use has been established. Once verified, the site
may be returned to the pool of available land.
Financial Surety
Return of site to pool
of available land
Long term stability
Safety
Future land use
Air emissions
Hazardous waste disposal
Governments increasingly move towards securing
adequate financial provisions to deal with closure liabilities
associated with mining operations.
Environmental financial sureties are one of the mechanisms
that governments have adopted to ensure that
companies meet closure liabilities.
Various forms of financial surety instruments have
been applied in different jurisdictions. Instruments
that leave the funds available for use by the company
may include:
Self-funding through financial reserves;
Balance sheet tests;
Asset pledges to government in the event of
default;
Parent company guarantees.
More commonly, governments require that producers
set aside financial resources. These instruments may
include:
Cash deposits with government institutions;
Trust funds;
Financial institution guarantees such as performance
bonds and letters of credit.
Mine Closure Case Study
In view of the large reserves and extended life of most
phosphate rock and potash mining operations, there
are few experiences of mine closure in the fertilizer
raw material mining industry to learn from and provide
guidance.
The MDPA potash operation in France has been
developing and implementing plans as it approaches
closure.
3.8 Rehabilitation
Rehabilitation activities generally involve the design
and creation of stable and safe landforms, followed by
the establishment of self-sustaining ecosystems to
replace those disturbed during the mining process.
The effectiveness of rehabilitation is enhanced by integration
with the mine plan and conducting it
progressively throughout the life of the mine. The
objectives of rehabilitation can range through a spectrum
of:
Complete restoration of the areas original natural
values;
Reclamation to re-establish the pre-mining land
use;
Development of a completely new land use for the
area, such as lakes, forestry or agriculture;
Leaving land of marginal value in a safe and stable
condition.
In some countries, the post-mining land use is determined
through discussion and consultation with
stakeholders, such as state and local government agen-