FIELD OF THE INVENTION
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The present invention relates to improvements in carpet recycling and more particularly to post consumer carpet recycling wherein the post consumer carpet is more readily separated into its component polymeric materials.
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OF THE INVENTION
Recycling of waste materials is ever increasing in popularity and mirrors the concerns that many people have for the environment. In some cities and regions, recycling is even mandatory. Very often, many people try to conserve natural resources and reuse components of products can help in that effort. One example of mandated recycling is illustrated by the many states that have enacted legislation requiring a deposit on the purchaser of beverage containers in the form of aluminum cans and plastic bottles. The production of aluminum from bauxite is a very energy intensive process and recycling of aluminum cans therefore a cost effective endeavor. Recycling of soda bottles made of polyethylene terephthalate (PET) is another area where recycling has been successfully applied.
Reusing the PET from beverage bottles to form carpet fibers is one area where recycling has achieved certain benefits. Besides reducing the cost of the raw materials, such recycling has also reduced the amount of materials being disposed within landfills. It is not uncommon for carpet manufacturers to use recycled two liter soda bottles in the production of polyester based carpeting. PET polyester carpet is manufactured with yarn created from reclaimed polyester resins.
Post consumer carpet recycling has not become very wide spread. Post consumer carpet refers to the carpet that had been installed in a house or office, but is in need of removal and replacement with new carpeting or other types of flooring. Until recently, once the carpet in a house or office had worn out and was removed, the only destination for disposal had been a landfill. Because of the type of ingredients used in carpet, i.e. thermoplastic polymeric materials, carpet materials are not very biodegradable, and once buried in a landfill, a carpet may take as much as 20,000 years to fully degrade. At the present time, nearly six billion pounds of carpet are discarded per year in the United States, and as landfill space becomes scarcer while petroleum based products become more expensive due to increased crude oil costs, the need to recycle post consumer carpet becomes more necessary and more cost effective.
Carpets like many other composite materials are difficult to recycle effectively because they comprise a number of components made from different materials that have been combined into a finished product. These individual components, once extracted from the post consumer carpet, have significantly more value than as the composite. Carpets are comprised of a backing which supports and hold together a plurality of fibers that extend from the backing, and which form the pile or surface that is walked on by the user. An adhesive based material may be used to secure the fibers to the backing, and is typically used to secure a secondary backing to the primary backing. Usually one type of polymeric material is used to make the fibers of the carpet pile, a different type of polymeric material is used to make the backing, while the adhesive used is frequently a third type of material. In many carpets, this face fiber that makes up the pile may be nylon, a polyolefin, a polyester, etc. The backing is usually a polypropylene material, although other materials may also be used. Because of the multiplicity of materials, carpet has been difficult to recycle into reusable constituent components because the materials that comprise the carpet can not be readily or easily separated into those individual polymers. While there are some uses for composite polymeric materials, the value of the recycled post consumer carpet increases significantly if the components are separated.
Because of the difficulties in separating the carpet components, some companies have resorted to reusing the carpet as a fuel, and burn the carpet as a source of heat instead of dumping it in a landfill. In the burning method of recycling, the carpet may be burned as a fuel and the heat is used to generate steam which can then be used to generate electricity. The heat generated by the burning carpet can also be used for other purposes. While this reduces landfill dumping, it is not an ideal means of recycling the carpet.
Another approach towards carpet recycling can include melting the carpet rather than burning it, and thereafter attempting to separate the components in the blend based upon their melting or vaporization points. But this process is energy intensive and requires complex equipment. This equipment necessary must prevent each of the distinctive material fibers from burning when, yet must allow them to be heated to the proper melting temperatures to facilitate separation of the components. Additionally, separating those melted composite of carpet materials is not easily performed. Because of the difficulty in separating the melted components of a carpet, this recycled material is usually not used for new carpet, but is instead used in such products like park benches, and other similar items where a blend of different polymers is not objectionable.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a system for recycling portions of carpets.
It is an object of the invention to provide an apparatus for recycling post consumer carpet.
It is also an object of the invention to provide a system for mechanically separating carpet components for recycling.
It is a further object of the invention to separate unsheared U's (the long U's) comprising the carpet pile from the backing.
It is a still further object of the invention to separate sheared U's (short U's) of carpet pile from the carpet backing.
It is another object of the invention to separate the remnant fiber portions of the carpet backing material from the U's.
It is a further object of the invention to separate the remaining adhesive still attached to the separated U's.
Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings.
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OF THE INVENTION
A carpet recycling apparatus, for use in separating pile, backing, and adhesive of post-consumer carpet may comprises three or four different stages of apparatus performing distinctly different operations. An important step in recycling post-consumer carpet involves identifying the particular fiber used in the carpet pile. Herein a sensor may be used to accomplish near infrared reflectance (NIR) or Raman spectroscopy, to identify the spectral signature of the particular polymer molecules of the pile currently being recycled by the apparatus. The sensor may be hand held and comprise a separate first stage, or the sensor may alternatively be integral to any one of the other three stages of the process.
A second stage apparatus may be for use in mechanically separating a substantial portion of pile from the backing(s). The second stage apparatus may consist of a drum having a cylindrical outer surface, with the drum being rotatably mounted, and with it comprising a plurality of pins protruding outward from the cylindrical surface. The pins may be generally equally spaced circumferentially about the cylindrical outer surface, and may be generally equally spaced laterally across the cylindrical surface. A curved feed dish may have a first end and a second end, with the second end terminating in proximity to the drum, and comprising a sharp edge. The feed dish may comprise curvature having a tangency being approximately tangent to a cylindrical surface formed by the ends of the plurality of pins.
To be able to easily feed post-consumer carpet into the apparatus at a reasonable rate, a feed belt revolving about a pair of rollers may be included. The feed belt may be as wide as the drum itself, which may be 12 feet wide to accommodate a full-width piece of post-consumer carpet to be processed without the need for it to be trimmed into smaller sections prior to recycling. One or more rollers being positioned proximate to the pinned drum, direct the carpet against the feed dish, whose curvature causes the carpet to engage the pins of the drum at an optimal angle for removal of the U\'s of the pile, and for shredding of the backing. A pile rejecting plate being in close proximity to said pins of the drum directs the rejected U\'s into a receptacle. A guide member may serve to help retain the shredded backing on the rotating drum, while pieces of dislodged adhesive may fall through perforations in the guide member for collection in a bin. Beyond the perforations, a source of negative pressure may be used to draw the shredded backing away from the drum and into a chute. The shredded backing may actually be a residual composite material comprising mainly the primary and secondary backing, as well as small pieces of remnant pile that remains attached to the shredded backing by the adhesive. The shredded backing may be sent to a press, while the separated U\'s, which may also comprise remnant backing fibers and some adhesive, is sent to the next stage for processing.
The first part of the third stage apparatus may comprise a condensing apparatus, which may be for use in drawing away any pieces of adhesive that was dislodged during from the pile U\'s during vacuum transportation to the third stage. A perforated squirrel cage divided into an upper portion and a lower portion may be used, by applying vacuum pressure to the sealed upper portion to draw away the dislodged pieces of adhesive. The U\'s may then drop into a buffer section, which may contain a series of paddle wheels usable to direct the pile U\'s into a weight pan, when necessary for a processing cycle. When the weight pan has received a set amount of material, it may open to drop that weight of residual composite material into a shaker pen. The shaker pen is usable for separating remnant backing fibers from the pile U\'s. The shaker pen comprises one or more walls having a top opening and a bottom opening, with the bottom opening of the shaker pen being covered by a pivotable mesh. The top opening may be sealed by a door. Shaking or vibrating of the shaker pen causes the remnant backing fibers to become dislodged from the U\'s, leaving the smaller U\'s to fall through the mesh openings, to be directed by a deflecting plate into a first conduit. After a set time period, after which most of the pile has been dislodged and removed, the mesh pivots to release the remaining backing fiber, which is then directed by the deflector plate into a second conduit.
A fourth stage of the process may be for use in mechanically separating a substantial portion of remaining adhesive from the separated pile U\'s. Removal of the adhesive still attached to the U\'s may occur through timed treatment of the U\'s through a hammering operation within a fibermill, after which the fiber may be ducted outward from the fibermill using vacuum pressure, while the crushed adhesive falls through a grill. A final step in the process may comprise baling, pelletizing, or agglomerating the separated post-consumer carpet components.
BRIEF DESCRIPTION OF THE DRAWINGS
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FIG. 1A is a perspective view of a representative section of carpet having loop pile face yarn.
FIG. 1B is a perspective view of a representative section of carpet having cut pile face yarn.
FIG. 2 is a side view showing the apparatus used at each stage of the recycling process in a second embodiment of the current invention, having a buffer silo in the third stage, and using a condenser at each of the third and fourth stages.
FIG. 2A is a side view showing the apparatus used at each stage of the recycling process in a first embodiment of the current invention, having a horizontal buffer arrangement, and using a condenser at each of the third and fourth stages.
FIG. 2B is a side view showing the apparatus used at each stage of the recycling process in a third embodiment of the current invention, having a horizontal buffer arrangement, and being without use of a condenser prior to the third and fourth stages.
FIG. 3 is an enlarged view of the second stage apparatus of FIG. 2.
FIG. 4 is a detail view of a portion of the apparatus of FIG. 3.
FIG. 4A is an enlarged view of the feed dish of FIG. 4.
FIG. 5 is an enlarged view of the third stage apparatus of FIG. 2.
FIG. 6 is an enlarged view of condenser portion of the apparatus of FIG. 2.