They take their first glimpse of the Tri-County Landfill. An enormous stretch of land is covered with piles of unusable materials. Not far from the trash compactor, Woody, Buzz, and the rest of their friends are transported by a conveyor belt through the mouth of a tunnel, where the initial process of waste separation takes place. The attraction of Slinky's coils to the magnetic ceiling gives the toys a clue that metal objects will experience an upward force and they quickly try to make an escape. This useful device seen in the film is commonly found in forms of different tools. It is practical in that it saves time by quickly removing ferrous metals (materials containing iron) from non-ferrous (or nonmagnetic) items like plastic, paper, and aluminum.

During the waste separation process, two types of magnetic devices are used: powered electromagnetic fields and permanent magnets. The first type is magnetized by running an electric current through wires. Electromagnets are easier to control and can be powered off when necessary. When it is charged, the device’s domains are positioned in the same direction. This device also works like a permanent magnet. As metal objects pass by, they are attracted to the electromagnetic force and the domains of the objects also become parallel. Without a charged source, they would point in various directions.
The second type, on the other hand, does not rely on a charged source since it is able to create a magnetic field on its own. Because permanent magnets contain materials like iron, its domains are preserved to aim at one direction.
magnets-domains.jpg
Domains from the image above are not arranged to reach a specific endpoint until after magnetization has occured.






*Domain: When a number of atoms line in the same direction


Process of Waste Separation

First, the pulley (circular wheel) rotates the belt conveyor, carrying the waste materials.
The strong magnetic force from the wheel causes an attraction of metal particles, such as iron and steel, to hold on to the surface of the conveyor until they are relocated to a separate area. The materials are then transported under the pulley and are discharged once it no longer comes in contact with the magnetic field.
The clean materials are transferred to another section for further processing.
To keep the non-magnetic items from mixing in with the ferrous metals, the pulley moves in a constant motion. Its momentum sends the materials to fall away from the area collecting metals.

magnetic_head_pulley_Sketch.gif
This is an image of a magnetic head pulley. A divider is located directly below the pulley, allowing a quick separation of waste particles.


Permanent magnets work as a recycling system, dividing materials into three types: aluminum, plastic and ferrous metal.
A second method used in removing metal from non-magnetic items is the "metal recovery." It is made of magnetic properties that allow it to pick up bits of metal.
Magnetic traps also play a crucial role in dividing ferrous materials. This device is suitable for liquid lines in order to purify them. The trap is submerged and it picks up smaller pieces of iron still left remaining in the liquid.
From the toys' adventure through the landfill, their discovery of the magnets presents a deeper meaning behind physics. They understood the simple idea of magnetic properties. The scene from the film reveals another aspect in that people have recognized the source of the domains, magnetic fields, and its power.


Additional Website:

http://www.iqsdirectory.com/industry/recycling_equipment/index.htm



Magnets used in Waste Separation

Works Cited

Capel, Claudine. “Waste Sorting- A Look at the Separation and Sorting Techniques in

Today’s European Market.” Waste Management World 16 March 2011

<“http://www.waste-management-world.com/index/display/article-display/339838/articles/waste-management-world/volume-9/issue-4/features/waste-sorting-a-look-at-the-separation-and-sorting-techniques-in-todayrsquos-european-market.html”>.
Best Practice in Glass Recycling.” CWC Nov. 1996. 13 March 2011

<“http://www.cwc.org/gl_bp/gbp2-0301.htm”>.

“End-of-Life Vehicle Management: Salvage Facilities and Vehicle Shredders.” EDF

16 March 2011

<“http://www.edf.org/documents/892_GC_salvage.htm”>.


Works Cited

Capel, Claudine. “Waste Sorting- A Look at the Separation and Sorting Techniques in

Today’s European Market.” Waste Management World 16 March 2011

<“http://www.waste-management-world.com/index/display/article-display/339838/articles/waste-management-world/volume-9/issue-4/features/waste-sorting-a-look-at-the-separation-and-sorting-techniques-in-todayrsquos-european-market.html”>.
Best Practice in Glass Recycling.” CWC Nov. 1996. 13 March 2011

<“http://www.cwc.org/gl_bp/gbp2-0301.htm”>.

“End-of-Life Vehicle Management: Salvage Facilities and Vehicle Shredders.” EDF

16 March 2011

<“http://www.edf.org/documents/892_GC_salvage.htm”>.




Works Cited

Capel, Claudine. “Waste Sorting- A Look at the Separation and Sorting Techniques in

Today’s European Market.” Waste Management World 16 March 2011

<“http://www.waste-management-world.com/index/display/article-display/339838/articles/waste-management-world/volume-9/issue-4/features/waste-sorting-a-look-at-the-separation-and-sorting-techniques-in-todayrsquos-european-market.html”>.
Best Practice in Glass Recycling.” CWC Nov. 1996. 13 March 2011

<“http://www.cwc.org/gl_bp/gbp2-0301.htm”>.

“End-of-Life Vehicle Management: Salvage Facilities and Vehicle Shredders.” EDF

16 March 2011

<“http://www.edf.org/documents/892_GC_salvage.htm”>.