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Recycling enables materials to be regenerated and different types of products to be manufactured. Some examples of current recycling operations:
Aluminium from drink cans, trays and aerosol canisters: on arrival at the sorting centre, aluminium packaging is separated and cleaned. It is then placed in very high- temperature ovens where it is melted down. From the liquid metal, ingots and rolls of alloy sheet are produced, which go off as completely new material into the manufacturing circuit. At the present, only 10% of aluminium is recycled: sorting centres are only slowly being put in place.
Glass: at the sorting centre, whole bottles are separated from broken glass and cleaned. They can be directly reused as bottles for drinks. Broken glass is cleansed of its impurities, ground into very small pieces and melted at 1550°C together with the materials used in glass
manufacturing
(sand, soda, limestone …) to produce new bottles and other objects. Recycling glass enables energy savings of 33% compared to manufacturing new glass.
Steel: this comes
mainly
all from food cans. At the sorting centre they are crushed in a press and transformed into big compacted blocks for dispatch to steel-making plants where they are melted down at 1500°C in a furnace to join the normal steel manufacturing circuit.
Plastic: for economic reasons, only bottles and flasks are recycled and not plastic bags and small wrappings. At the sorting centre, three types of plastic are carefully separated:
- PVC (polyvinylchloride) from tubing, windows, gloves;
- PET (polyethylene terephtalate) from drink bottls and food trays;
- HDPE (high density polyethylene) from milk bottles, supermarket bags and packaging for household cleaning products.
They are ground, washed
and regenerated into a pure powder or granular product. One water
bottle recycled provides the input for 7 silicon chips!
Paper and cardboard: collected in the sorting centre, they are compressed into bundles and ground in a giant mixer with water. The resulting paper fibre pulp has its impurities removed, and the inks are cleaned away. The pulp is then wrung out, drained and dried by passing it between heated cylinders. After a final treatment, the large rolls of recycled paper are ready for use. Some 40% of the paper used worldwide is recycled paper.
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