Page 204 - Materials Chemistry, Second Edition

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Sustainability of Municipal Solid Waste Management
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there is no increase in air pollution when these residual materials are burnt
in comparison with coal. This alternative is considered to be both economi-
cally and environmentally feasible.
The European Aluminum Foil Association (2005) stated that an inno-
vative process is used by the Corenso recycling plant in Finland that recov-
ers fiber, converts the plastic layers of used multilayer packaging into gas
for energy, and recovers aluminum. The Corenso recycling plant processes
125,000 tons of mixed packaging waste into 250 GWh of heat and electricity
per year. Around 3,000 tons of aluminum is recovered. Anonymous (2001)
described the recovery of aluminum content together with the generation of
steam and electricity from the polyethylene material. The PE/Al mixture is
heated up to a temperature of 400°C in a gas reactor with air blown into it to
make sure that there is about 40% air. The polyethylene content changes to
gas that is used to heat a steam boiler up to 1,300°C, as a result of which
process steam is produced and electricity is generated with the help of a
back pressure turbine. Pure aluminum is recovered and separated with the
help of a cyclone, then used to manufacture a variety of aluminum products.
This process contributes to huge energy savings in addition to the produc-
tion of significantly fewer air emissions in comparison to the use of other
fuels such as coal or oil.
According to Alcao Aluminio Inc. (2005), a carton packaging recycling
facility in Brazil uses groundbreaking plasma technology which enables the
total separation of aluminum and plastic components contained in the aseptic
packages. The application of plasma technology for the recycling of carton
packaging utilizes electrical energy to produce a jet of plasma at 15,000°C to
heat the plastic and aluminum mixture. Plastic is transformed into paraffin
and the aluminum is recovered in the form of high purity ingot. The level of
pollutants emitted during the recovery of the materials is minimal. The
process is handled in the absence of oxygen, and it does not involve com-
bustion; the energy efficiency rate is close to 90%. The plasma process thus
provides another option for recycling, allowing for the return of all three
components of the package to the productive chain as raw material closing
the loop of materials. The paper, extracted during the first phase of the recy-
cling process is transformed into cardboard. Alcoa Inc., which supplies thin-
gauge aluminum foil for the manufacture of aseptic packages, uses the recycled
aluminum to manufacture new foils, and paraffin is sold to the Brazilian
petrochemical industry.

Thermal compression
Anonymous (2001) described a recycling process that uses the beverage car-
ton as a whole to produce a new material called TECTAN. The used bever-
age cartons are chopped then pressed and heated to a temperature of 170°C
with the help of Teflon-coated metal plates. The polyethylene content in
the chopped cartons melts and bonds the chips together forming a plate.