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The
electrolytic reduction process requires the use of fluorides compounds,
namely sodium fluoride and Aluminium fluoride in order to improve
properties of the electrolytic bath. The addition of fluoride generates
energy savings in the order of 50% since it allows for the electrolytic
process to be operated at a temperature of approximately 960oC.
Source: Ministère de l'Environnement et de la Faune du Québec
Given the high temperature inside the electrolytic pot, some of
the fluoride is released to the atmosphere. Two methods are used
to reduce fluoride emissions. In older smelters, the addition of
lithium in the electrolytic bath reduces the quantity of fluoride.
It is treated in wet scrubbers before being exhausted to atmosphere.
The water used in the scrubbers is processed and re-circulated.
In modern smelters, exhaust from pots is captured by an advanced
exhaust system and routed to be taken to gas treatment centres where
alumina is injected into the gas stream and the fluoride is adsorbed
by the alumina. This fluoride-enriched alumina is recovered and
distributed to the electrolytic pots. Continuous monitors are used
to measure the efficiency of gas treatment centres. These centres
achieve an exhaust removal performance of over 99%.
The smelters also implement strict monitoring of both flora and
fauna within a radius of several kilometres from the facilities.
Monitoring of the local environment indicate that fluoride concentrations
in forage are below the limit in all locations
Minimising
the Damage of Mining
Bauxite,
the ore that is processed into Aluminium, is extracted from open
mine sites located in tropical and subtropical areas of the globe.
About four tonnes of bauxite are needed to produce one tonne of
Aluminium. The mining extraction of large quantities of bauxite
leaves marks that need to be corrected when the mine ceases to be
operated.
In order to minimise consequences of mining activity on the ecosystems,
producers use operating methods that foster full site restoration.
Once a site is mined-out, the affected area is graded and covered
with a topsoil cover, often the same one that was removed at the
beginning of mining operations. This allows for restoration of the
land to its original or other beneficial use, depending of the requirements
of local communities.
The results achieved are truly remarkable, from Australia to Jamaica:
new forests are born, wildlife are recovered or, alternatively,
dairy farms are being operated over former mining sites. Such results
are possible thanks to the involvement of local communities.
This is a true example of sustainable development
Recycling
Aluminium Cans
Any
comprehensive solution to the problem of solid waste disposal must
include recycling, reusing materials, extracting resources from
waste products and producing less material in the first place.
The recycling of Aluminium beverage cans not only reduces waste,
it saves energy, conserves natural resources, lessens use of municipal
landfills and provides recyclers and municipalities with considerable
revenue. In short, the Aluminium can performs well in two of the
world's major problem areas: It is good for the environment and
good for the economy.
One cannot discuss protecting the environment without talking about
recycling and resource recovery. In fact, it is nearly impossible
to contemplate a global solution to the elimination of waste without
thinking in terms of the selection and reuse of recyclable materials,
efficient packaging or reduced energy consumption. In any such discussion,
the recycling of Aluminium, which uses 95 percent less energy than
the production of primary metal from raw materials, constitutes
a choice solution in addressing today's environmental concerns.
More so, when one considers that, because of its nature and unlike
more fragile materials, Aluminium can be recycled almost indefinitely.
The recycling of Aluminium uses 95 percent less energy than the
production of primary metal from raw materials.
Each year, in Canada alone, 1.5 billion Aluminium cans are recovered,
shredded, cleaned and re-melted to produce new cans. This results
in the country saving enough energy to cover the energy needs of
15,000 homes for one year.
The Aluminium can is 100% recyclable; there are no labels or covers
to be removed. Recycling one kilogram of Aluminium can save about
eight kilograms of bauxite, four kilograms of chemical products
and fourteen kilowatt-hours of electricity
The energy needed to produce each tonne of primary Aluminium has
been reduced by over 30% in the last 35 years.
Even though Aluminium cans represent less than 1% of solid waste,
they are so valuable they should all be recycled.
In Canada, each person on average produces more than 600 kilograms
of household solid waste a year. The Aluminium industry encourages
and supports curb-side recycling programs as a way of reducing solid
waste, and fosters the " 3 Rs " of environmentally sensitive solid
waste management: Reduce, Re-use and Recycle.
Aluminium
should be considered a raw material and never waste material.
Anything made of Aluminium can be recycled indefinitely: not only
cans, but Aluminium foil, plates and pie moulds, window frames,
garden furniture, are melted down and used to make the same products
again.
Today's Aluminium can requires about 40% less metal than the can
made 25 years ago; this means less need of both energy and raw materials
per can.
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Number
of 12-ounce cans fabricated from one pound of 484 grams
of Aluminium*
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1972
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21,75
cans
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1975
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23,00
cans
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1980
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24,23
cans
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1985
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26,60
cans
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1990
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30,00
cans
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1995
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30,50
cans
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*
Source: Aluminium Recycling - The Aluminium Association
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An
8,000 kilogram sheet ingot makes over half-a-million cans !
However, Aluminium recycling is not limited to cans. It also involves
recovery and re-smelting of various items, construction materials,
automobile parts or process scrap. It is expected that by the year
2000 recycled metal will account for 40% of the world's Aluminium
consumption. Already more than 80% of automobile parts made of Aluminium
are recycled and the amount of Aluminium used in cars increases
every year. Soon we will have automobiles that can be recycled entirely.
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