Page 78 - Solid Waste Analysis and Minimization a Systems Approach

56 BACKGROUND AND FUNDAMENTALS OF SOLID WASTE ANALYSIS AND MINIMIZATION

This section provides an overview of each step. Before being transported to an alu-
minum recycling facility, the material is passed under a magnet to remove any steel.
Aluminum is a nonferrous metal, so it is not magnetic. Steel is a ferrous metal, so it is
magnet. The magnet picks up the steel cans and separates them from aluminum. The
remaining cans are then crushed and compressed to form bales and transported to the
aluminum recycling facility.
Once at the facility, the cans are shredded into small pieces about 1 inch in diameter.
These pieces then pass through a magnet which removes any remaining ferrous metals
such as steel. The shredded aluminum then travels to a de-coater, where hot air (at
930 F) removes any coating or decoration.
The hot cans go straight from the de-coater to the furnace, where they are melted
at a temperature of 1300 F. Once melted, the liquid aluminum is transferred to a hold-
ing furnace which clears any remaining contaminants, and a degasser which removes
any gas.
The liquid aluminum is poured into cooled rectangular shaped moulds. The cooling
transforms the aluminum back into a solid metal. This solid metal is taken to a saw
where the ends are made square and transported to the rolling facility. At the rolling
facility the aluminum is rolled into large sheets to be used as raw material.

2.8.4 GLASS RECYCLING

Different types of glass go through different recycling processes. For example, cook-
ware melts at a much higher temperature than container glass and must be processed
separately. This section follows the typical recycling process of container glass (such
as beverage bottles). There are four types of glass related to recycling processes:

1 Container glass (wine and beer bottles)
2 Float glass (windows)
3 Cookware (plates and dishes)
4 Automotive glass (windshields)

Glass for recycling is mostly collected from businesses or community drop-off
sites. Trucks collect the bottles and transport them to be stored in a depot. When a pro-
cessing batch of glass has been collected and delivered to the depot, it is all transported
to a glass-recycling facility.
Once at the recycling facility, the glass is crushed. Crushed glass is called cullet.
Cullet goes through many processes to remove nonglass items. To remove ferrous
metal, the cullet is passed through a strong magnet which removes the ferrous metals
such as steel and iron. The removed nonferrous metals, the cullet, passes by powerful
air jets which separate the metal pieces from the cullet. To remove lightweight items,
such as paper, the cullet goes through a vacuum. To remove any remaining items that
are not glass, such as ceramics, the cullet passes under a laser which rejects them. The
cullet is now ready to be made into new glass. To make new glass, the cullet goes into
a furnace where it is melted at a temperature of 2700 F. The high temperature turns
the cullet into a liquid called molten glass. The molten glass is shaped into molds to