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BAUXITE AND ALUMINA
Apart from land use associated with
bauxite mining, which is discussed in the Natural
Resource Stewardship section of this report, the
Bauxite and Alumina group's key environmental challenges
include controlling dust and managing waste emissions
such as bauxite residue.
Dust
Dust control is an area of focus in bauxite mining and
alumina processing, as it can potentially impact employees
and communities due to airborne particulates. While
associated health impacts are taken very seriously by
Alcan, another area of concern is the settling dust
that can mar the appearance of the surrounding worksite
and community. If recovered, however, the dust can be
added back into bauxite production, a resource otherwise
lost.
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| Scott Fingen, Materials
Handling Supervisor, and Mark Quinlan, Materials
Handling Operator, in the bauxite stock pile
area in Gove, Australia. |
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As an example of advances being made in this area, the Compagnie
des Bauxites de Guinée (CBG) has introduced of gas
scrubbers at its plant. As a result, dust emissions are now
being collected from the gas stream and bauxite is being recovered
for reuse. Prior to this, some 50 tonnes of dust from bauxite
ore dryers was being released into the air every day. The
goal is to reduce the dust emissions to 500 mg/Nm3
in phase I, and then down to 50 mg/Nm3
in phase II, a World Bank standard. Phase I is expected to
be completed by June 2005, and phase II, by 2007. Recovery
of the airborne dust will not only clean up the surrounding
worksite and community, it will also return the great majority
of the dust to the bauxite production.
At the QAL alumina facility in Australia, investments in 2003
and 2004 resulted in significant improvements in dust emissions.
A new calcination plant has produced a 95% reduction in alumina
dust emissions; fly ash emissions have been reduced from 80
mg/Nm3 to less than 10 mg/Nm3;
dust emissions from unloading coal trains was dramatically
reduced; and capital projects were started to reduce alkali
emissions.
Bauxite Residue
The bauxite refining process generates large quantities of
bauxite residue as the mixture of water, inert residues (including
iron oxide, which results in the red colour) and diluted caustic
soda remaining after the alumina is extracted from the bauxite.
Bauxite residue is the largest environmental concern of alumina
refineries due to its volume and alkalinity. Limited storage
space for bauxite residue has heightened the need to develop
sustainable alternatives for its use or disposal.
With this focus, the group has established general goals
to minimize the quantity of residue per tonne of alumina produced;
minimize the soda content in any residue sent to disposal
sites; and, keep the size of disposal areas to a minimum
and rehabilitate them as early as possible.
Alcan aims to deliver on stakeholder expectations through
ongoing demonstration of improved performance in managing
bauxite residue, and these perceptions are important to Alcan's
reputation. Substantial efforts have been made to improve
disposal technologies and practices and major improvements
have been achieved, such as a unique process in Vaudreuil,
Quebec where the materials used to build dikes to store bauxite
residue have actually been replaced by bauxite residue. This
has diverted a significant percentage of the bauxite residue
that needs to be stored.
Furthermore, efforts have also been undertaken to find alternative
uses including the extraction of valuable materials and/or
the development of commercial and sustainable applications/products.
Two other examples of bauxite residue management are improvements
in residue disposal technology and stacking at Vaudreuil
Works in Canada, where a 50% reduction in the disposal
area has been achieved and, at Gardanne
in France, where a product called Bauxaline shows promise
in road construction and as ground cover for waste disposal
sites.
Though it remains a challenge for the global aluminum industry,
the group continues to explore these and potential technical
solutions to find new applications and products for bauxite
residue. Due to the often-remote locations of our operations,
transportation costs for potential customers are a factor
when the assessing economic viability of using bauxite residue
in their business. It is part of Alcan's strategic plan to
continue efforts in this area, including better management
of volumes generated and their disposal, as well as treatment
of disposal and developing alternative applications.
Bauxite residue
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| in millions of tonnes |
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| 2004 |
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4.3 |
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| 2003 |
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3.13 |
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| 2002 |
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2.78 |
| The increase in bauxite residue in 2004 is mainly due
to the Pechiney acquisition. |
Bauxite residue rate
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| in tonnes of bauxite residue per tonne of alumina hydrate produced |
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| 2004 |
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0.89 |
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| 2003 |
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1.01 |
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| 2002 |
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0.84 |
| Excludes bauxite residue from joint ventures outside
of Alcan's internal reporting system. |
Marine Impacts
Some of our bauxite and alumina facilities operate in very
close proximity to salt water marine environments.
The ecological risks to the marine environment associated
with potential impacts from these operations are a key issue
for both Alcan and its stakeholders. Alcan manages these potential
risks by taking a holistic view of marine systems from all
perspectives and potential company impacts, thereby allowing
for the proper identification and planning for internal control
responses to these environmental risks.
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