CA2206759A1 - Recovery of nylon fibre from carpet - Google Patents
Recovery of nylon fibre from carpetInfo
- Publication number
- CA2206759A1 CA2206759A1 CA002206759A CA2206759A CA2206759A1 CA 2206759 A1 CA2206759 A1 CA 2206759A1 CA 002206759 A CA002206759 A CA 002206759A CA 2206759 A CA2206759 A CA 2206759A CA 2206759 A1 CA2206759 A1 CA 2206759A1
- Authority
- CA
- Canada
- Prior art keywords
- carpet
- nylon
- screen
- nylon fibre
- fibre
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01G—PRELIMINARY TREATMENT OF FIBRES, e.g. FOR SPINNING
- D01G11/00—Disintegrating fibre-containing articles to obtain fibres for re-use
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/66—Disintegrating fibre-containing textile articles to obtain fibres for re-use
Landscapes
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
Abstract
A method for the recovery of nylon fibre from nylon carpet, including roll carpet and carpet tile, is disclosed. The method comprises comminution of the carpet, separation using a screen, agitating in an aqueous solution and subjecting the resultant solution to at least one centrifugal cleaner and at least one screen before dewatering and recovery of nylon fibre.
Description
.CA 022067~9 1997-06-02 RECOVERY OF NYLON FIBRE FROM CARPET
The present invention relates to a method for the recovery of nylon fibre from carpet, and in particular to a method of recovery of nylon fibre from either used or scrap unused carpets, or parts thereof, including both roll carpets and carpet tiles, especially as part of the recycling of nylon carpet.
There are a variety of methods for the manufacture of nylon carpet, depending on the particular style of carpet, and of nylon carpet tile. In general, nylon carpet and carpet tile have nylon fibre on one surface and a carpet backing on the opposite surface. The nylon fibre is anchored into the carpet, either through use of the carpet backing or by other techniques. For instance, in a tufted pile carpet, pile yarn is tufted into a primary carpet backing in a needle punching operation.
Subsequently, the underside of the tufted primary carpet backing is coated with a polymeric latex or hot melt adhesive material to encapsulate the yarns and provide an adhesive surface on the underside of the carpet. A
variety of polymers may be used in the latex or hot melt adhesive layer. The primary backing may also be a variety of sheet or woven materials, the latter including woven polymer tapes, scrims and jute.
In view of the complex and varied nature of the construction of carpets and carpet tile, it is difficult to efficiently and effectively separate the fibre from the backing and other materials in the carpet or carpet tile. In addition, most carpet or carpet tile intended for recycle is used carpet, which would be soiled and contain dirt, sand and other contaminants.
The difficulties of recycling carpeting having, for example, nylon tufts, latex adhesive and polypropylene backing is known, and referred to as difficult to impossible in WO 97/06004 of R. Akki et al, which discloses a pile surface structure for the manufacture of lightweight carpet that is easily recycled. Separating CA 022067~9 1997-06-02 components of carpet material for recycling by milling and use of solutions of different density, adjusted by addition of a salt, is disclosed in US Patent 5 598 980.
Recyclable carpets that are formed from polyamide tufts, polyamide backings and polyamide adhesives are disclosed in EP 625 605. A carpet recycling separation process in which carpet is shredded and granulated to reduce the carpet to less than 4 square inches, hammer-milled to liberate carpet backing and then sifted e.g. using a shaker conveyer is disclosed in Research Disclosure 388013.
A method has now been found for recovery of nylon fibre from nylon carpet, including roll carpet and carpet tile.
Accordingly, an aspect of the present invention provides a method for the separation and recovery of nylon fibre from a nylon carpet, said nylon carpet comprising nylon fibre and backing material, said method comprising:
a) comminuting said nylon carpet;
b) subjecting the comminuted nylon carpet to at least one screen to separate at least part of said backing material from material containing said nylon fibre;
c) feeding nylon fibre obtained from step b) to a vessel containing an aqueous solution, agitating material containing said nylon fibre and effecting further separation of backing material from said material containing nylon fibre;
d) subjecting aqueous solution containing nylon fibre from the vessel in step c) to at least one centrifugal cleaner for separation of heavy particulate matter and at least one screen to separate aqueous solution containing nylon fibre;
e) dewatering the aqueous solution containing nylon fibre from step d); and f) recovering nylon fibre.
CA 022067~9 1997-06-02 In a preferred embodiment of the method of the present invention, the aqueous solution in step d) is subjected sequentially to a screen of a first mesh size and to a screen of a second mesh size, said first mesh size being larger than said second mesh size.
In another embodiment of the present invention, the aqueous solution obtained from step d) is subjected to a dynamic washer to reduce the water content of said solution prior to dewatering in step e).
In a further embodiment, the comminution of nylon carpet in step a) includes, in sequence, a step in which the nylon carpet is shredded and a step in which the shredded nylon carpet so obtained is subjected to at least one of grinding, pulverising and hammer milling.
In a still further embodiment, the screen in step b) is at least one of a shaker screen and a rotary screen.
In yet another embodiment, the nylon carpet that is comminuted in step a) is one of roll carpet and carpet tile.
In a still another embodiment, the at least one centrifugal cleaner and the at least one screen of step (d) may be in any sequence or combination of sequences.
The present invention is illustrated by the embodiment shown in the drawings, in which:
Fig. 1 is a schematic representation of the method of the invention; and Fig. 2 is a schematic representation of the aqueous section of an embodiment of the method.
Fig. 1 shows a comminution device, generally indicated by 1, a screen generally indicated by 2, a vessel generally indicated by 3, a centrifugal cleaner generally indicated by 4, a screen generally indicated by 5 and a de-watering apparatus generally indicated by 6.
The method of the invention is intended to be used with respect to nylon (polyamide) carpet. Such carpet may be in a wide variety of forms, including in the form of scraps or off-cuts of carpet from processes for the -CA 022067~9 1997-06-02 manufacture or installation of carpet e.g. roll carpet or carpet tile, including various pieces of such roll carpet or carpet tile. The roll carpet and carpet tile could be new (unused) carpet but would more likely be carpet or carpet tile that had been removed after an extended period of use e.g. for replacement with new carpet. Such used carpet, in particular, would be soiled e.g. contain significant quantities of dirt, sand and other contaminant matter. The carpet would normally have been previously separated from other types of carpet, if necessary, prior to being subjected to the method of the invention. Techniques for the separation of nylon carpet from other types of carpet are known, and include chemical tests and centrifuge tests.
In the method of the invention, the carpet is fed to a comminution device 1 for comminution of the carpet.
Comminution device 1 would normally be a two-stage comminution device, with the first stage being for instance a shredder that is capable of shredding the carpet to a first coarse particle size e.g. particulate having diameters in the range of 0.5-0.75 inches, although a wide range of sizes could be used and the particle size distribution is likely very broad. The primary purpose of the shredder is to assist in the comminution of the carpet into a particulate size suitable for processing according to the invention, and it would normally be difficult to obtain a suitable particulate size in a one-step operation. For instance, it is believed that there is an optimum range of particulate size, with particulate that is too fine being susceptible to difficulties in separation in density separation processes, in that such processes would not effect a density separation or would exhibit parachuting or carry-over of one type of fine particle with a different type of fine particle. The second stage of comminution is intended to reduce the particulate size of the shredded carpet to achieve a suitable particulate size for screening, and subsequent steps in the process CA 022067~9 1997-06-02 as described below e.g. an optimum and relatively uniform range of particulate size, and would for instance be a hammer mill, a grinder or a pulveriser. Fibre length of the comminuted carpet is believed to be important, especially for separations involving differences in - density.
The particulate or comminuted carpet passing from comminution device 1, through transfer pipe 11 to screen 2 would need to be of a particulate size commensurate with the mesh size of the screen. The mesh size of the screen is selected so as to effect a primary separation of particulate matter that is carpet backing from particulate matter containing nylon fibre. The carpet backing particulate would be of a greater size than the carpet fibre particulate. Examples of screen 2 are a shaker screen or a rotary screen.
The particulate carpet fibre fraction from screen 2 would be passed through screen outlet 12 into vessel 3.
The particulate carpet backing separated in screen 2 would be passed through rejection line 13. It is to be understood that screen 2 could be a plurality of screens.
Particulate matter passing through screen rejection line 13 could be subjected to further comminution e.g. by recycling to comminution device 1, or subjected to further screening e.g. using one or a plurality of screens in screen rejection line 13, so as to effect a separation of a higher proportion of the nylon fibre-containing particulate for feeding to vessel 3.
Vessel 3 contains an aqueous solution. The nylon fibre-containing particulate fed to vessel 3 is agitated in the aqueous solution to effect further separation of nylon fibre from backing material remaining in the particulate fed to vessel 3. In addition, vessel 3 could have a pulper or other device to assist in further comminution or separation of the particulate in vessel 3.
Aqueous solution containing a suspension of the comminuted carpet material passes from vessel 3 through vessel outlet 14. Vessel outlet 14 is shown as passing CA 022067~9 l997-06-02 in sequence to centrifugal cleaner 4 and screen 5.
However, it is to be understood that vessel outlet 14 could pass to a screen prior to centrifugal cleaner 4 and/or that centrifugal cleaner 4 and screen 5 could be multiple banks of such cleaners and screens in any combination and sequence. Centrifugal cleaner 4 and screen 5 are intended to effect separation of nylon fibre from carpet backing remaining in the suspension. As noted above, because the carpet used in the method would normally be used carpet, it would contain particles of sand, soil, grit or other material. Such particles would likely be separated using one or both of centrifugal cleaner 4 and screen 5.
An example of centrifugal cleaner 4, which is also known as a hydrocyclone cleaner, is a Posiflow cleaner which is obtainable from Beloit Jones Division of Beloit Corporation, Stilton, MASS, U.S.A. Such a cleaner effects removal of heavy particulate matter as a reject stream, passing lighter matter through the hydrocyclone cleaner as an "accept" stream. Thus, if vessel outlet 14 passes to centrifugal cleaner 4, the cleaner is operated so that centrifugal cleaner outlet 15 contains a higher proportion of nylon fibre, whereas centrifugal cleaner reject line 16 contains a higher proportion of other particulate material, compared to the particulate material fed to the centrifugal cleaner. It is understood that centrifugal cleaner reject line 16 could be fed to other centrifugal cleaners to effect a more efficient separation of fibre from other material, with the fibrous material being recycled e.g. to vessel 3 or centrifugal cleaner 4.
In the embodiment shown in Fig. 1, centrifugal cleaner outlet 15 passes from centrifugal cleaner 4 to screen 5. Screen 5 has a mesh size suitable for separation of nylon fibre from other particulate material in the feed stream to screen 5. Nylon fibre passes through screen outlet 17 to de-watering apparatus 6.
Other particulate matter passes from screen 5 to screen CA 022067~9 1997-06-02 reject line 18. As noted above, a series of screens could be used, including a series of screens of differing mesh sizes, generally decreasing in size along the series.
De-watering apparatus 6 effects a separation of nylon fibre from aqueous solution. The aqueous solution, or slurry, being fed to dewatering apparatus 6 should have a high proportion of nylon fibre, with the solids content of the slurry preferably being at least 90% nylon fibre and especially at least 99% nylon fibre. Nylon fibre passes through de-watering apparatus outlet 19, whereas aqueous solution separated therefrom would normally be recycled through water recycle line 20 back to vessel 3.
Reject streams from any part of the process of the present invention may be recycled back to the process if the stream contains sufficient nylon fibre. Otherwise, it is preferred that the reject streams be fed to apparatus capable of forming useful products from such reject streams and/or to recover useful products therefrom and feed sand and other particu~ate matter to a waste disposal site.
The aqueous solution in the vessel may contain a wetting agent to improve the wetting of the fibre and facilitate movement of the fibre and separation thereof in the method of the invention. It is understood that carpets frequently have anti-static, anti-soiling agents or the like applied thereto, either during the process of manufacture of the carpet, or subsequent thereto by users of the carpet in order improve the long term aesthetic properties of the carpet. Many of such added agents tend to prevent wetting of the carpet fibres, and addition of wetting agents to vessel 3 might be necessary in order to adequately wet the fibre for passage through for example screens used in the process. In addition, a sanitising agent may also be added to vessel 3 in order to treat any bacteria or the like that may be on the fibre.
CA 022067~9 1997-06-02 .
Screen 5 may be a coarse screen followed by a fine screen in order to effect separation in a two-stage manner. The coarse screen would remove larger pieces of contaminants and/or other material e.g. carpet backing still in the solution, while allowing nylon fibre to pass through. As an example, such a screen may be, for instance, a rotating screen with a mesh size of the order of 10-12 thousandths of an inch. The fine screen would be of a finer mesh e.g. a mesh size of 4-6 thousandths of an inch, and would be used for further cleaning and separation of contaminant material present with the nylon fibre. Such a screen may also be a rotating screen.
It is understood that a mixing tank may be placed between the coarse screen and the fine screen, especially in that the composition e.g. concentration, also known as consistency, of the mixture or slurry suitable for operation of a coarse screen might be different from that suitable for operation of a fine screen, with the latter generally requiring a more dilute solution. For instance, a typical solution fed to a coarse screen may contain about 1.5-3% w/w of particulate matter, whereas a typical solution fed to a fine screen may contain about 1% w/w of particulate matter.
The solution passing through screen outlet 17 and being fed to de-watering apparatus 6 may be fed to an intervening dynamic washer, which is used to thicken the slurry i.e. separate water therefrom prior to the resultant slurry being fed to the de-watering apparatus.
Water separated in such a dynamic washer would normally be recycled to vessel 3.
In operation of the method illustrated in Fig. 1, nylon carpet is fed to comminution device 1, normally being subjected to a shredding operation and then a grinding operation. In addition to the components of the nylon carpet, particularly nylon fibre and backing, the carpet would normally also contain dirt, sand and other contaminant matter. Comminuted carpet is fed from comminution device 1 to screen 2 in order to effect a CA 022067~9 1997-06-02 primary separation of carpet backing from carpet fibre.
Carpet backing separated by screen 2 could be subjected to further comminution and recycle to effect separation of nylon fibre, further screening or other treatment to separate nylon fibre or fed directly to landfill or preferably to another process for the manufacture of useful products. The nylon fibre component passing from screen 2 is fed to vessel 3, where it is admixed and possibly comminuted further in aqueous solution. Aqueous solution with the nylon fibre component in the form of a slurry passes from vessel 3 and is fed, in the embodiment illustrated in Fig. 1, to a centrifugal cleaner 4. Heavy particulate matter is removed in centrifugal cleaner 4, with the nylon fibre-containing component being fed to screen 5. As discussed above, centrifugal cleaner 4 could be in the form of a plurality of cleaners in series. Alternatively, one or more screens 5 could be inserted prior to centrifugal cleaners 4. In addition, as discussed above, screen 5 could be in the form of a coarse screen and a fine screen in series, with matter e.g. nylon fibre, passing through the fine screen being fed to the de-watering apparatus. Additional centrifugal cleaner could be inserted between screen 5 and de-watering apparatus 6. In addition, dilution tanks could be inserted in the process before or after centrifugal cleaner 4 and screen 5 in order to achieve a consistency of the solution for optimum operation of centrifugal cleaner 4 and screen 5. The nylon fibre-containing material passing from screen 5 through screen outlet 17 may be fed to de-water~ing apparatus directly or through a dynamic washer to effect concentration of the solution prior to feeding to the de-watering apparatus. De-watering apparatus 6 would normally be in the form of a press. Water passing therefrom would normally be recycled to vessel 3.
Fig. 2 illustrates an embodiment of the part of the method of the invention involving use of the aqueous solution. It is understood that carpet would be CA 022067~9 1997-06-02 comminuted and screened, as described previously, before being fed through inlet 30A to vessel 30. In vessel 30, the comminuted material is contacted and mixed with water, optionally with wetting or other agents as described previously. Aqueous solution in the form of a slurry of comminuted material in water is fed from vessel 30 to centrifugal cleaner 31 in which heavy material is separated. It is understood the centrifugal cleaner 31 would be operated to pass nylon fibre through the "accept" outlet, rather than the "reject" outlet. Heavy, reject, material from centrifugal cleaner 31 is forwarded to reject outlet 47.
Nylon fibre-containing material is passed from centrifugal cleaner 31 to coarse screen 32. Material rejected by coarse screen 32 is passed to reject feed tank 35, whereas the "accept" of nylon fibre-containing material is fed to a mixing tank, to adjust the concentration of the slurry if necessary, before feeding to fine screen 34. Rejects from fine screen 34 are also fed to reject feed tank 35. The material in reject feed tank 35 is fed to reject screen 36. Accepted material from reject screen 36 is admixed with accepted material from fine screen 34 and subjected to further processing, whereas rejected material is fed to reject outlet 47.
The "accept" material from fine screen 34 and reject screen 36 is fed to dilution tank 37 and then to centrifugal cleaner 38. Accept material from centrifugal cleaner 38 is fed to dilution tank 40. Reject material from centrifugal cleaner 38 is fed through cleaner reject tank 42 and then to centrifugal cleaner 39. Reject material from centrifugal cleaner 39 is sent to reject outlet 47, whereas accept material is fed to dilution tank 40. Material is fed from dilution tank 40 to dynamic washer 41. The aqueous solution separated in dynamic washer 41 is recycled to vessel 30, whereas the concentrated solution (slurry) passing from dynamic washer 41 passes to dilution tank 43, for adjustment of concentration, and then to second dynamic washer 44.
CA 022067~9 1997-06-02 Nylon fibre passing from second dynamic washer 44 passes to press 45, where it is dried and is sent to nylon fibre recovery 46. Aqueous solution separated in second dynamic washer 44 and press 45 is recycled to dilution tank 40.
The method of Fig. 2 illustrates use of multiple centrifugal cleaners, screens and dilution tanks, with recycle of solutions to recover nylon fibre and for reuse in the system.
In its overall context, the present invention provides a method of separating nylon fibre from a carpet without requiring shearing or heating techniques in order to facilitate such a separation.
The present invention relates to a method for the recovery of nylon fibre from carpet, and in particular to a method of recovery of nylon fibre from either used or scrap unused carpets, or parts thereof, including both roll carpets and carpet tiles, especially as part of the recycling of nylon carpet.
There are a variety of methods for the manufacture of nylon carpet, depending on the particular style of carpet, and of nylon carpet tile. In general, nylon carpet and carpet tile have nylon fibre on one surface and a carpet backing on the opposite surface. The nylon fibre is anchored into the carpet, either through use of the carpet backing or by other techniques. For instance, in a tufted pile carpet, pile yarn is tufted into a primary carpet backing in a needle punching operation.
Subsequently, the underside of the tufted primary carpet backing is coated with a polymeric latex or hot melt adhesive material to encapsulate the yarns and provide an adhesive surface on the underside of the carpet. A
variety of polymers may be used in the latex or hot melt adhesive layer. The primary backing may also be a variety of sheet or woven materials, the latter including woven polymer tapes, scrims and jute.
In view of the complex and varied nature of the construction of carpets and carpet tile, it is difficult to efficiently and effectively separate the fibre from the backing and other materials in the carpet or carpet tile. In addition, most carpet or carpet tile intended for recycle is used carpet, which would be soiled and contain dirt, sand and other contaminants.
The difficulties of recycling carpeting having, for example, nylon tufts, latex adhesive and polypropylene backing is known, and referred to as difficult to impossible in WO 97/06004 of R. Akki et al, which discloses a pile surface structure for the manufacture of lightweight carpet that is easily recycled. Separating CA 022067~9 1997-06-02 components of carpet material for recycling by milling and use of solutions of different density, adjusted by addition of a salt, is disclosed in US Patent 5 598 980.
Recyclable carpets that are formed from polyamide tufts, polyamide backings and polyamide adhesives are disclosed in EP 625 605. A carpet recycling separation process in which carpet is shredded and granulated to reduce the carpet to less than 4 square inches, hammer-milled to liberate carpet backing and then sifted e.g. using a shaker conveyer is disclosed in Research Disclosure 388013.
A method has now been found for recovery of nylon fibre from nylon carpet, including roll carpet and carpet tile.
Accordingly, an aspect of the present invention provides a method for the separation and recovery of nylon fibre from a nylon carpet, said nylon carpet comprising nylon fibre and backing material, said method comprising:
a) comminuting said nylon carpet;
b) subjecting the comminuted nylon carpet to at least one screen to separate at least part of said backing material from material containing said nylon fibre;
c) feeding nylon fibre obtained from step b) to a vessel containing an aqueous solution, agitating material containing said nylon fibre and effecting further separation of backing material from said material containing nylon fibre;
d) subjecting aqueous solution containing nylon fibre from the vessel in step c) to at least one centrifugal cleaner for separation of heavy particulate matter and at least one screen to separate aqueous solution containing nylon fibre;
e) dewatering the aqueous solution containing nylon fibre from step d); and f) recovering nylon fibre.
CA 022067~9 1997-06-02 In a preferred embodiment of the method of the present invention, the aqueous solution in step d) is subjected sequentially to a screen of a first mesh size and to a screen of a second mesh size, said first mesh size being larger than said second mesh size.
In another embodiment of the present invention, the aqueous solution obtained from step d) is subjected to a dynamic washer to reduce the water content of said solution prior to dewatering in step e).
In a further embodiment, the comminution of nylon carpet in step a) includes, in sequence, a step in which the nylon carpet is shredded and a step in which the shredded nylon carpet so obtained is subjected to at least one of grinding, pulverising and hammer milling.
In a still further embodiment, the screen in step b) is at least one of a shaker screen and a rotary screen.
In yet another embodiment, the nylon carpet that is comminuted in step a) is one of roll carpet and carpet tile.
In a still another embodiment, the at least one centrifugal cleaner and the at least one screen of step (d) may be in any sequence or combination of sequences.
The present invention is illustrated by the embodiment shown in the drawings, in which:
Fig. 1 is a schematic representation of the method of the invention; and Fig. 2 is a schematic representation of the aqueous section of an embodiment of the method.
Fig. 1 shows a comminution device, generally indicated by 1, a screen generally indicated by 2, a vessel generally indicated by 3, a centrifugal cleaner generally indicated by 4, a screen generally indicated by 5 and a de-watering apparatus generally indicated by 6.
The method of the invention is intended to be used with respect to nylon (polyamide) carpet. Such carpet may be in a wide variety of forms, including in the form of scraps or off-cuts of carpet from processes for the -CA 022067~9 1997-06-02 manufacture or installation of carpet e.g. roll carpet or carpet tile, including various pieces of such roll carpet or carpet tile. The roll carpet and carpet tile could be new (unused) carpet but would more likely be carpet or carpet tile that had been removed after an extended period of use e.g. for replacement with new carpet. Such used carpet, in particular, would be soiled e.g. contain significant quantities of dirt, sand and other contaminant matter. The carpet would normally have been previously separated from other types of carpet, if necessary, prior to being subjected to the method of the invention. Techniques for the separation of nylon carpet from other types of carpet are known, and include chemical tests and centrifuge tests.
In the method of the invention, the carpet is fed to a comminution device 1 for comminution of the carpet.
Comminution device 1 would normally be a two-stage comminution device, with the first stage being for instance a shredder that is capable of shredding the carpet to a first coarse particle size e.g. particulate having diameters in the range of 0.5-0.75 inches, although a wide range of sizes could be used and the particle size distribution is likely very broad. The primary purpose of the shredder is to assist in the comminution of the carpet into a particulate size suitable for processing according to the invention, and it would normally be difficult to obtain a suitable particulate size in a one-step operation. For instance, it is believed that there is an optimum range of particulate size, with particulate that is too fine being susceptible to difficulties in separation in density separation processes, in that such processes would not effect a density separation or would exhibit parachuting or carry-over of one type of fine particle with a different type of fine particle. The second stage of comminution is intended to reduce the particulate size of the shredded carpet to achieve a suitable particulate size for screening, and subsequent steps in the process CA 022067~9 1997-06-02 as described below e.g. an optimum and relatively uniform range of particulate size, and would for instance be a hammer mill, a grinder or a pulveriser. Fibre length of the comminuted carpet is believed to be important, especially for separations involving differences in - density.
The particulate or comminuted carpet passing from comminution device 1, through transfer pipe 11 to screen 2 would need to be of a particulate size commensurate with the mesh size of the screen. The mesh size of the screen is selected so as to effect a primary separation of particulate matter that is carpet backing from particulate matter containing nylon fibre. The carpet backing particulate would be of a greater size than the carpet fibre particulate. Examples of screen 2 are a shaker screen or a rotary screen.
The particulate carpet fibre fraction from screen 2 would be passed through screen outlet 12 into vessel 3.
The particulate carpet backing separated in screen 2 would be passed through rejection line 13. It is to be understood that screen 2 could be a plurality of screens.
Particulate matter passing through screen rejection line 13 could be subjected to further comminution e.g. by recycling to comminution device 1, or subjected to further screening e.g. using one or a plurality of screens in screen rejection line 13, so as to effect a separation of a higher proportion of the nylon fibre-containing particulate for feeding to vessel 3.
Vessel 3 contains an aqueous solution. The nylon fibre-containing particulate fed to vessel 3 is agitated in the aqueous solution to effect further separation of nylon fibre from backing material remaining in the particulate fed to vessel 3. In addition, vessel 3 could have a pulper or other device to assist in further comminution or separation of the particulate in vessel 3.
Aqueous solution containing a suspension of the comminuted carpet material passes from vessel 3 through vessel outlet 14. Vessel outlet 14 is shown as passing CA 022067~9 l997-06-02 in sequence to centrifugal cleaner 4 and screen 5.
However, it is to be understood that vessel outlet 14 could pass to a screen prior to centrifugal cleaner 4 and/or that centrifugal cleaner 4 and screen 5 could be multiple banks of such cleaners and screens in any combination and sequence. Centrifugal cleaner 4 and screen 5 are intended to effect separation of nylon fibre from carpet backing remaining in the suspension. As noted above, because the carpet used in the method would normally be used carpet, it would contain particles of sand, soil, grit or other material. Such particles would likely be separated using one or both of centrifugal cleaner 4 and screen 5.
An example of centrifugal cleaner 4, which is also known as a hydrocyclone cleaner, is a Posiflow cleaner which is obtainable from Beloit Jones Division of Beloit Corporation, Stilton, MASS, U.S.A. Such a cleaner effects removal of heavy particulate matter as a reject stream, passing lighter matter through the hydrocyclone cleaner as an "accept" stream. Thus, if vessel outlet 14 passes to centrifugal cleaner 4, the cleaner is operated so that centrifugal cleaner outlet 15 contains a higher proportion of nylon fibre, whereas centrifugal cleaner reject line 16 contains a higher proportion of other particulate material, compared to the particulate material fed to the centrifugal cleaner. It is understood that centrifugal cleaner reject line 16 could be fed to other centrifugal cleaners to effect a more efficient separation of fibre from other material, with the fibrous material being recycled e.g. to vessel 3 or centrifugal cleaner 4.
In the embodiment shown in Fig. 1, centrifugal cleaner outlet 15 passes from centrifugal cleaner 4 to screen 5. Screen 5 has a mesh size suitable for separation of nylon fibre from other particulate material in the feed stream to screen 5. Nylon fibre passes through screen outlet 17 to de-watering apparatus 6.
Other particulate matter passes from screen 5 to screen CA 022067~9 1997-06-02 reject line 18. As noted above, a series of screens could be used, including a series of screens of differing mesh sizes, generally decreasing in size along the series.
De-watering apparatus 6 effects a separation of nylon fibre from aqueous solution. The aqueous solution, or slurry, being fed to dewatering apparatus 6 should have a high proportion of nylon fibre, with the solids content of the slurry preferably being at least 90% nylon fibre and especially at least 99% nylon fibre. Nylon fibre passes through de-watering apparatus outlet 19, whereas aqueous solution separated therefrom would normally be recycled through water recycle line 20 back to vessel 3.
Reject streams from any part of the process of the present invention may be recycled back to the process if the stream contains sufficient nylon fibre. Otherwise, it is preferred that the reject streams be fed to apparatus capable of forming useful products from such reject streams and/or to recover useful products therefrom and feed sand and other particu~ate matter to a waste disposal site.
The aqueous solution in the vessel may contain a wetting agent to improve the wetting of the fibre and facilitate movement of the fibre and separation thereof in the method of the invention. It is understood that carpets frequently have anti-static, anti-soiling agents or the like applied thereto, either during the process of manufacture of the carpet, or subsequent thereto by users of the carpet in order improve the long term aesthetic properties of the carpet. Many of such added agents tend to prevent wetting of the carpet fibres, and addition of wetting agents to vessel 3 might be necessary in order to adequately wet the fibre for passage through for example screens used in the process. In addition, a sanitising agent may also be added to vessel 3 in order to treat any bacteria or the like that may be on the fibre.
CA 022067~9 1997-06-02 .
Screen 5 may be a coarse screen followed by a fine screen in order to effect separation in a two-stage manner. The coarse screen would remove larger pieces of contaminants and/or other material e.g. carpet backing still in the solution, while allowing nylon fibre to pass through. As an example, such a screen may be, for instance, a rotating screen with a mesh size of the order of 10-12 thousandths of an inch. The fine screen would be of a finer mesh e.g. a mesh size of 4-6 thousandths of an inch, and would be used for further cleaning and separation of contaminant material present with the nylon fibre. Such a screen may also be a rotating screen.
It is understood that a mixing tank may be placed between the coarse screen and the fine screen, especially in that the composition e.g. concentration, also known as consistency, of the mixture or slurry suitable for operation of a coarse screen might be different from that suitable for operation of a fine screen, with the latter generally requiring a more dilute solution. For instance, a typical solution fed to a coarse screen may contain about 1.5-3% w/w of particulate matter, whereas a typical solution fed to a fine screen may contain about 1% w/w of particulate matter.
The solution passing through screen outlet 17 and being fed to de-watering apparatus 6 may be fed to an intervening dynamic washer, which is used to thicken the slurry i.e. separate water therefrom prior to the resultant slurry being fed to the de-watering apparatus.
Water separated in such a dynamic washer would normally be recycled to vessel 3.
In operation of the method illustrated in Fig. 1, nylon carpet is fed to comminution device 1, normally being subjected to a shredding operation and then a grinding operation. In addition to the components of the nylon carpet, particularly nylon fibre and backing, the carpet would normally also contain dirt, sand and other contaminant matter. Comminuted carpet is fed from comminution device 1 to screen 2 in order to effect a CA 022067~9 1997-06-02 primary separation of carpet backing from carpet fibre.
Carpet backing separated by screen 2 could be subjected to further comminution and recycle to effect separation of nylon fibre, further screening or other treatment to separate nylon fibre or fed directly to landfill or preferably to another process for the manufacture of useful products. The nylon fibre component passing from screen 2 is fed to vessel 3, where it is admixed and possibly comminuted further in aqueous solution. Aqueous solution with the nylon fibre component in the form of a slurry passes from vessel 3 and is fed, in the embodiment illustrated in Fig. 1, to a centrifugal cleaner 4. Heavy particulate matter is removed in centrifugal cleaner 4, with the nylon fibre-containing component being fed to screen 5. As discussed above, centrifugal cleaner 4 could be in the form of a plurality of cleaners in series. Alternatively, one or more screens 5 could be inserted prior to centrifugal cleaners 4. In addition, as discussed above, screen 5 could be in the form of a coarse screen and a fine screen in series, with matter e.g. nylon fibre, passing through the fine screen being fed to the de-watering apparatus. Additional centrifugal cleaner could be inserted between screen 5 and de-watering apparatus 6. In addition, dilution tanks could be inserted in the process before or after centrifugal cleaner 4 and screen 5 in order to achieve a consistency of the solution for optimum operation of centrifugal cleaner 4 and screen 5. The nylon fibre-containing material passing from screen 5 through screen outlet 17 may be fed to de-water~ing apparatus directly or through a dynamic washer to effect concentration of the solution prior to feeding to the de-watering apparatus. De-watering apparatus 6 would normally be in the form of a press. Water passing therefrom would normally be recycled to vessel 3.
Fig. 2 illustrates an embodiment of the part of the method of the invention involving use of the aqueous solution. It is understood that carpet would be CA 022067~9 1997-06-02 comminuted and screened, as described previously, before being fed through inlet 30A to vessel 30. In vessel 30, the comminuted material is contacted and mixed with water, optionally with wetting or other agents as described previously. Aqueous solution in the form of a slurry of comminuted material in water is fed from vessel 30 to centrifugal cleaner 31 in which heavy material is separated. It is understood the centrifugal cleaner 31 would be operated to pass nylon fibre through the "accept" outlet, rather than the "reject" outlet. Heavy, reject, material from centrifugal cleaner 31 is forwarded to reject outlet 47.
Nylon fibre-containing material is passed from centrifugal cleaner 31 to coarse screen 32. Material rejected by coarse screen 32 is passed to reject feed tank 35, whereas the "accept" of nylon fibre-containing material is fed to a mixing tank, to adjust the concentration of the slurry if necessary, before feeding to fine screen 34. Rejects from fine screen 34 are also fed to reject feed tank 35. The material in reject feed tank 35 is fed to reject screen 36. Accepted material from reject screen 36 is admixed with accepted material from fine screen 34 and subjected to further processing, whereas rejected material is fed to reject outlet 47.
The "accept" material from fine screen 34 and reject screen 36 is fed to dilution tank 37 and then to centrifugal cleaner 38. Accept material from centrifugal cleaner 38 is fed to dilution tank 40. Reject material from centrifugal cleaner 38 is fed through cleaner reject tank 42 and then to centrifugal cleaner 39. Reject material from centrifugal cleaner 39 is sent to reject outlet 47, whereas accept material is fed to dilution tank 40. Material is fed from dilution tank 40 to dynamic washer 41. The aqueous solution separated in dynamic washer 41 is recycled to vessel 30, whereas the concentrated solution (slurry) passing from dynamic washer 41 passes to dilution tank 43, for adjustment of concentration, and then to second dynamic washer 44.
CA 022067~9 1997-06-02 Nylon fibre passing from second dynamic washer 44 passes to press 45, where it is dried and is sent to nylon fibre recovery 46. Aqueous solution separated in second dynamic washer 44 and press 45 is recycled to dilution tank 40.
The method of Fig. 2 illustrates use of multiple centrifugal cleaners, screens and dilution tanks, with recycle of solutions to recover nylon fibre and for reuse in the system.
In its overall context, the present invention provides a method of separating nylon fibre from a carpet without requiring shearing or heating techniques in order to facilitate such a separation.
Claims (6)
1. A method for the separation and recovery of nylon fibre from a nylon carpet, said nylon carpet comprising nylon fibre and backing material, said method comprising:
a) comminuting said nylon carpet;
b) subjecting the comminuted nylon carpet to at least one screen to separate at least part of said backing material from material containing said nylon fibre;
c) feeding nylon fibre obtained from step b) to a vessel containing an aqueous solution, agitating material containing said nylon fibre and effecting further separation of backing material from said material containing nylon fibre;
d) subjecting aqueous solution containing nylon fibre from the vessel in step c) to at least one centrifugal cleaner for separation of heavy particulate matter and at least one screen to separate aqueous solution containing nylon fibre;
e) dewatering the aqueous solution containing nylon fibre from step d); and f) recovering nylon fibre.
a) comminuting said nylon carpet;
b) subjecting the comminuted nylon carpet to at least one screen to separate at least part of said backing material from material containing said nylon fibre;
c) feeding nylon fibre obtained from step b) to a vessel containing an aqueous solution, agitating material containing said nylon fibre and effecting further separation of backing material from said material containing nylon fibre;
d) subjecting aqueous solution containing nylon fibre from the vessel in step c) to at least one centrifugal cleaner for separation of heavy particulate matter and at least one screen to separate aqueous solution containing nylon fibre;
e) dewatering the aqueous solution containing nylon fibre from step d); and f) recovering nylon fibre.
2. The method of Claim 1 in which the aqueous solution in step d) is subjected sequentially to a screen of a first mesh size and to a screen of a second mesh size, said first mesh size being larger than said second mesh size.
3. The method of Claim 1 in which the aqueous solution obtained from step d) is subjected to a dynamic washer to reduce the water content of said solution prior to dewatering in step e).
4. The method of Claim 1 in which the comminution of nylon carpet in step a) includes, in sequence, a step in which the nylon carpet is shredded and a step in which the shredded nylon carpet so obtained is subjected to at least one of grinding, pulverising and hammer milling.
5. The method of Claim 1 in which the screen in step b) is at least one of a shaker screen and a rotary screen.
6. The method of Claim 1 in which the nylon carpet that is comminuted in step a) is one of roll carpet and carpet tile.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002206759A CA2206759A1 (en) | 1997-06-02 | 1997-06-02 | Recovery of nylon fibre from carpet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002206759A CA2206759A1 (en) | 1997-06-02 | 1997-06-02 | Recovery of nylon fibre from carpet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2206759A1 true CA2206759A1 (en) | 1998-12-02 |
Family
ID=4160799
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002206759A Abandoned CA2206759A1 (en) | 1997-06-02 | 1997-06-02 | Recovery of nylon fibre from carpet |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2206759A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7635099B1 (en) * | 2005-11-29 | 2009-12-22 | Mohawk Carpet Corporation | Component recovery process |
| US8205814B2 (en) | 2005-11-29 | 2012-06-26 | Mohawk Carpet Distribution, Inc. | Filler recovery processes |
| EP2526144A2 (en) * | 2010-01-18 | 2012-11-28 | Invista Technologies S.à.r.l. | Processes to clean and recycle carpet fiber and thermoplastics made from such processes |
-
1997
- 1997-06-02 CA CA002206759A patent/CA2206759A1/en not_active Abandoned
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7635099B1 (en) * | 2005-11-29 | 2009-12-22 | Mohawk Carpet Corporation | Component recovery process |
| US8205814B2 (en) | 2005-11-29 | 2012-06-26 | Mohawk Carpet Distribution, Inc. | Filler recovery processes |
| US8708259B2 (en) | 2005-11-29 | 2014-04-29 | Mohawk Carpet Distribution, Inc. | Filler recovery processes |
| EP2526144A2 (en) * | 2010-01-18 | 2012-11-28 | Invista Technologies S.à.r.l. | Processes to clean and recycle carpet fiber and thermoplastics made from such processes |
| EP2526144A4 (en) * | 2010-01-18 | 2013-06-26 | Invista Tech Sarl | Processes to clean and recycle carpet fiber and thermoplastics made from such processes |
| AU2011205670B2 (en) * | 2010-01-18 | 2015-08-27 | Invista Technologies S.Ar.L. | Processes to clean and recycle carpet fiber and thermoplastics made from such processes |
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