THE RECYCLING PROCESS

RECYCLING GLASS
— Discarded glass is sorted at recycling center by color. The three color categories are green, amber or brown, and clear or flint glass. The broken or mixed glass can be crushed for use in asphalt road surfaces.
— Different colored piles are taken to a processing center.
— Glass is cleaned and crushed. Small pieces are called “cullet.” Cullet must be separated by color, be contaminant free, must meet market specifications, and must be container glass.
— Cullet is taken to glass manufacturing plants, and mixed with sand, soda ash and limestone.
— This mixture is fed into a furnace and melted into a thick liquid.
— The liquid can be dropped into a glass forming machine, then poured into molds to become any glass product.
(http://www.consrv.ca.gov/dor/edu/ReGlass.htm. The California Department of Conservation, Division of Recycling.
http://www.gpi.org/Handling.html, The Glass Packaging Institute
http://www.earth-organics.com/recycled_glass.htm.)

RECYCLING WOOD
Wood can either be salvaged from demolition projects, cleaned and resold as is or be reprocessed:
— Material is collected and transported to a processing facility.
— The facility checks for contaminants, such as paint or other chemicals.
— The material is fed into a chip washer to remove rocks and metals, then fed into a large box with an auger at the bottom. The auger pushes the material through a small opening, crushing and tearing it into smaller pieces.
— The material is placed on a vibrating deck, which removes grit, soil, rocks and metal, then sent through a chip washer to further remove foreign material.
— The material fed into a “hog mill” for further size reduction, then conveyed to a “chip truck” for use in other products.
(http://www.cwc.org/wood/wd971rpt.pdf)

RECYCLING RUBBER
— Used tires are taken to a rubber recycling plant.
— The tire recycler removes the steel bead surrounding the inner core of the tire.
— The tire is shredded into strips no larger than three inches.
— Remaining portions of steel and other non-rubber elements are removed.
— The rubber is ground into chips the size of grains of sand.
— Product is marketed to manufacturers of athletic or recreational surfaces, rubberized asphalt pavements, irrigation, soil and drainage systems, or rubberized flooring products.
(http://www.isri.org/industryinfo/rubber.htm,
Institute of Scrap Recycling Industries, 1325 G. St. NW, Suite 1000, Washington, D.C. 20005-3104
http://www.isri.org)

RECYCLING METAL and STEEL
– Scrap steel is transported to a steel mill.
– Steel is placed in one of two furnaces. One furnace uses a minimum of 25 percent steel scrap to make new steel for use in flat-rolled steel products. The other furnace melts 100 percent steel scrap to make new steel used primarily to make products that are long shapes, like steel plate, rebar and structural beams.
(http://www.recycle-steel.org/construction/index.html. Steel Recycling Institute, (1-800-937-1226).
At http://www.recycle-steel.org/database/index.html there is a steel recycling location database that allows users to search for a steel recycling location near them.

RECYCLING ZINC-COATED STEEL
— Zinc-coated steel is placed in an Electric Arc Furnace, which separates the zinc from the steel. The zinc travels with other gases out of the furnace into a chamber where it is treated. The zinc is collected in dust form.
— The zinc dust receives an “enrichment process” in rotary kiln, resulting in zinc oxide, a raw material for the production of new zinc.
(http://www.iza.com/zwo_org/Basics/ZincProtects/ZP1105/110501.htm)

RECYCLING ALUMINUM
— Scrap aluminum transported to processing plant.
— Scrap is checked and sorted to determine quality.
— Material is passed under large magnets to remove ferrous metals.
— Material is sent to a furnace, which melts it completely.
— Molten material is then recast or processed into new products.
-- Aluminum scrap is classified as “old scrap,” which is post-consumer material such as aluminum cans or window frames. “New scrap” is post-industrial material such as trimmings and manufacture surplus.
Check out the International Aluminum Institute, http://www.world-aluminum.org/production/recycling/process.html)

RECYCLING PLASTIC
Reprocessing of post-consumer milk bottles made of high-density polyethylene (HDPE):
— Bottles are collected, sorted by color and baled by recycler.
— Bales are transported to raw material vendors, who crush and bale them.
— Bales are taken to a processing facility, where they are broken apart, sorted and granulated into a raw flake material by color.
— Pieces of label, foil and other material is removed in a cleaning and washing process.
— An extrusion and pelletization process transforms the flake materials into finished goods.
See http://www.recycline.com/process.html. Recycline, Inc., 236 Holland St., Somerville, MA 02144
(888) 354-7296.

RECYCLING PAPER
— Waste paper is transported to a processor.
— Paper is sorted and baled by type — newspaper, bond paper, and magazine.
— Bales are soaked in large vats which allows them to disintegrate into fibers.
— Chemicals are added that allow ink particles to separate from the paper and reattach to the pulp.
— The pulp is sent though a series of fine screens to removed ink and other contaminants.
— Screened pulp is sent through a series of cleaning stages involving heat, chemicals and mechanical action. In a flotation device, more chemicals and soap are added to remove remaining ink.
— Pulp is sent to a stock preparation machine, where it can either be remade into paper or transported to other manufacturers for other uses.
See the Institute of Paper Science and Technology - Atlanta, http://www.ipst.edu/amp/museum_recycling.htm)
Other sources:
— City of Kingston, Ontario, Canada
http://www.city.kingston.on.ca/residents/waste/recycling/rec4.asp
— The Oregon Department of Environmental Quality (DEQ) http://www.deq.state.or.us/wmc/solwaste/aftercollection.html