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Tailings stored in dams and impoundments are theoretically
supposed to remain forever, but in reality many storage facilities
fail. When mines were small-scale operations, the storage of
tailings was not given a lot of consideration and waste was
stored poorly or just dumped into valleys or rivers (and there
are many old abandoned mine sites that cause environmental
damage today as tailings do not necessarily become “safer”
with time). Improved technology has made it economical to
mine progressively lower grade ores, resulting in larger mines
and the production of more and more tailings that need to
be permanently quarantined from the environment. A review
of major tailings dam failures in the period 1910 to 2010 by
Bowker and Chambers (2015) found a trend towards failures of
increasing magnitude and negative impact, and concluded that
the scale of future disasters could require cleanup operations
that were beyond the economic capacity of mining companies.
Some of the largest mines in the world, and consequently
the largest waste dumps, are found in mountain regions and
statistically it appears that some of these storage dams will fail
in the future (Morgenstern et al 2015). The 2015 dam collapse
at the Germano iron ore mine located in ranges of Minas Gerais
in southeastern Brazil, illustrates the social, environmental and
economic impact of a giant dam failure. The collapse flooded
the village of Bento Rodrigues killing 19 people and spreading
toxic red mud for more than 700 km across two states (Hatje
Examples of some existing best practice guidelines, documents and initiatives related
to mining waste
“Reference document on Best Available Techniques
for Management of Tailings and Waste-Rock in Mining
Activities”:
In 2009, after an accident in Baia Mare
(2000), Romania, the European Commission released
this document, which as the name suggests describes
best available techniques for mining of the metals, coal
and selected industrial minerals. It includes rock-waste
management and tailings management (European
Commission, 2009)
“Safety guidelines and good practices for tailings
management facilities”:
The United Nations Economic
Commission (UNECE) for Europe issued this report in 2010
to supporting policymakers and the business sector in
enhancing awareness and the sharing of experience and
good practices among the competent authorities, operators
and the public. Another aim of this document is the better
harmonization of the regulations and requirements
concerning the safety of tailings management facilities
(TMF) in the ECE region (UNECE, 2014)
“Best Practice in Environmental Management of
Uranium Mines”:
the International Atomic Energy Agency
(IAEA) released this document in 2010 with the objective to
provide both operators and regulators with guidelines and
examples of the implementation of the principles of best
practice to the uranium mining and processing industry.
(IAEA, 2010)
International Council on Mining and Metals (ICCM):
ICMM
is an international organisation whose goal is to improve
the social and environmental performance of the mining
and metals industry. ICCM brings together 23 mining and
metals companies and 34 regional commodities associations,
identifying common challenges and working to establish a
safer and more sustainable industry. (ICMM, 2016)
2016). If a failure of this magnitude occurred high up in the
mountains the consequences could be even more devastating
and geographically extensive.
Perpetual waste: Waste generated after the
mine has closed
Mine restoration in mountain areas is difficult due to the steep
slopes, often thin, poor topsoil and high intensity rainfall events.
In addition, disturbed areas can be very extensive - open pit mines
constitute some of the largest man-made structures. Some mine
sites are just abandoned, with no attempt at restoration – this is
especially common inareas that haveexperienced informalmining,
in developing countries and or mines in developed countries that
operated prior to effective environmental legislation. Without
restoration, abandoned mine sites experience long-term erosion
and leaching from tailings impoundments and waste rock dumps.
Hard rock mines (associated with ores containing sulphides and
minerals like gold, silver, iron, copper, zinc, nickel, tin and lead) can
also be a source of environmentally damaging acid mine drainage.
Long after the economic minerals have been exhausted, acidic
waste can still be generated from the mine, stored tailings and
exposed rock. When iron sulphide minerals, common in many
mineral deposits, are exposed to air and water, they react to form
sulfuric acid and dissolved iron (the iron can precipitate, forming