U.S. patent application number 17/805370 was filed with the patent office on 2022-09-15 for advanced manufacturing system to recycle carpet.
The applicant listed for this patent is XT Green, Inc.. Invention is credited to Gail Brice, Frank Lu, Lorence Moot, Xinting Tian.
Application Number | 20220288602 17/805370 |
Document ID | / |
Family ID | 1000006377506 |
Filed Date | 2022-09-15 |
United States Patent
Application |
20220288602 |
Kind Code |
A1 |
Tian; Xinting ; et
al. |
September 15, 2022 |
ADVANCED MANUFACTURING SYSTEM TO RECYCLE CARPET
Abstract
An advanced manufacturing plant and process to efficiently
deconstruct and recycle post-consumer carpet primarily in an
aqueous environment. The water-based technology substantially
eliminates airborne particulate emissions into the workplace and
the environment. It also significantly increases the quality and
quantity of the resources recovered from the carpet. In addition to
recycling residential carpet, it also reclaims and recycles
material from commercial broadloom carpet.
Inventors: |
Tian; Xinting; (Beijing,
CN) ; Brice; Gail; (Sunset Beach, CA) ; Moot;
Lorence; (Orlando, FL) ; Lu; Frank; (Chino
Hills, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
XT Green, Inc. |
Irvine |
CA |
US |
|
|
Family ID: |
1000006377506 |
Appl. No.: |
17/805370 |
Filed: |
June 3, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16749878 |
Jan 22, 2020 |
11376606 |
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17805370 |
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15587251 |
May 4, 2017 |
10576478 |
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16749878 |
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15346598 |
Nov 8, 2016 |
9676917 |
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15587251 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B02C 23/08 20130101;
B29L 2031/7322 20130101; C08J 11/06 20130101; B29B 17/02 20130101;
C08J 2377/00 20130101; B02C 23/00 20130101; B29B 2017/0289
20130101; B29B 17/0412 20130101; Y02W 30/62 20150501; B29B 2017/022
20130101; B29B 2017/0089 20130101; B29B 2017/0251 20130101; C08J
2323/12 20130101 |
International
Class: |
B02C 23/08 20060101
B02C023/08; C08J 11/06 20060101 C08J011/06; B29B 17/02 20060101
B29B017/02 |
Claims
1. A carpet recycling plant for separating nylon fibers,
polypropylene fibers and calcium carbonate from post-consumer
carpet, the plant comprising: an air controlled room which provides
additional control of airborne particulates; a shredder for gross
size reduction of the carpet to a size of about 4''.times.4'' to
about 8''.times.8'', the shredder located within the air controlled
room to capture air-born particulates emitted from carpet processed
through the shredder; an air exhaust of the air controlled room in
fluid communication with a water based pulper to capture
particulates from the air controlled room to the water based
pulper; a pulper filled with water which receives the gross size
reduced carpet and the captured particulates to create a carpet
slurry and further break down the gross sized reduced carpet to
enable the removal of the calcium carbonate/SBR latex nodules to
form a slurry of mixed fibers and ash; a water based refiner in
fluid communication with the pulper to cut fibers in the slurry
outputted from the pulper to a length sufficiently short to allow
for fiber separation in a multistage centrifuge; the multi-stage
centrifuge receiving the sufficiently short carpet fiber slurry
from the water based refiner; wherein after the gross size reduced
carpet and the captured particulates enter the pulper, the mixed
fiber and ash remain wet until at least after the calcium carbonate
and other ash particles are removed for recycling prior to the
centrifuge and the mixed fiber are separated through the
multi-stage centrifuge.
2. The plant of claim 1 wherein the nylon fibers and the
polypropylene fibers remain in a slurry of less than 6% solids
after introducing the gross size reduced carpet and the captured
particulates into the water based pulper and before being outputted
by the centrifuge.
3. The plant of claim 1 further comprising a water storage tank and
wherein the water storage tank is positioned at a higher elevation
compared to the pulper so that water from the water storage tank is
introduced into the pulper by gravity feed.
4. The plant of claim 3 wherein water from the storage tank is
introduced into the pulper so that the slurry of gross size reduced
carpet and ash particles has about 6% solid to water ratio.
5. The plant of claim 1 further comprising a first washer and
de-water unit wherein the carpet slurry is processed through the
first washer and de-water unit after being processed through the
wet pulper to remove the calcium carbonate/SBR nodule in order to
separate out the nylon and polypropylene fibers from the calcium
carbonate and water and other solids.
6. The plant of claim 5 further comprising a water treatment area
wherein the calcium carbonate and water from the first washer and
de-water unit are transferred to the water treatment area to remove
the water from the calcium carbonate so that the calcium carbonate
is greater than 30% calcium carbonate and collected for recycling
and the water is cleaned and returned to a water storage tank which
feeds water into the pulper.
7. The plant of claim 5 further comprising a refiner and wherein
the nylon fibers and polypropylene fibers are cut to a short length
in the water-based refiner so that the nylon fibers and
polypropylene fibers do not form a bird's nest configuration and
that the fibers cut in water do not heat up and cause undue changes
to the chemical and physical make-up of the fibers.
8. The plant of claim 7 wherein the nylon fibers and polypropylene
fibers are cut to about 5 mm long.
9. The plant of claim 1 further comprising a second washer and
de-water unit in fluid communication with the refiner which
receives the short length nylon and polypropylene fibers and
agitates the nylon and polypropylene fibers to rub off and clean
the residue on an exterior surface of the nylon and polypropylene
fibers and further separates the remaining calcium carbonate and
water from the nylon and polypropylene fibers, the separated
calcium carbonate and water are transferred to a water treatment
area to remove the water from the calcium carbonate so that the
calcium carbonate is greater than 30% calcium carbonate for
collection and recycling and the water is returned to a water
storage tank which feeds water into the pulper.
10. The plant of claim 9 further comprising a centrifuge feed tank
which receives the nylon and polypropylene fibers from the second
washer and de-water unit and receives water to bring the solids
percentage to about 2% solids.
11. The plant of claim 10 wherein the nylon and polypropylene
fibers at a 2% solids with water are introduced into the centrifuge
to separate the nylon fibers from the polypropylene fibers.
12. The plant of claim 11 further comprising a polypropylene
dewater unit that receives the polypropylene fibers from the
centrifuge to bring a moisture content of the polypropylene fibers
down below 30% and a polypropylene fiber dryer to bring the
moisture content of the polypropylene fibers down to about 3%
water.
13. The plant of claim 10 further comprising a nylon fiber dryer
that receives the nylon fibers from the centrifuge to bring the
moisture content of the nylon fibers down to about 3% water.
14. The plant of claim 1 wherein the multi stage centrifuge is a
two stage centrifuge.
15. The plant of claim 1 wherein a purity of the fibers exiting the
multi-stage centrifuge is 90 to 99.5%
16. The plant of claim 1 further comprising: a pulper wash and
dewater unit to wash and remove a majority of calcium carbonate and
other ash components from a pulper carpet slurry outputted from the
water based pulper; a water based refiner in fluid communication
with the pulper wash and dewater unit to cut fibers outputted from
the pulper wash and dewater unit to a length sufficiently short to
allow for fiber separation in the multi stage centrifuge; a refiner
wash unit in fluid communication with the water based refiner to
remove any remaining ash.
17. A process of recycling carpet to separate nylon fibers,
polypropylene fibers and calcium carbonate from the carpet, the
process comprising the steps of: receiving carpet in an air
controlled room; introducing carpet into a shredder which is
located in the air controlled room; trapping particulates emitted
from the shredder within an air controlled room; transferring the
trapped particulates from the air controlled room to a wet pulper
which is located outside of the air controlled room; transferring
gross size reduced carpet outputted from the shredder into the wet
pulper; maintaining the ash particles and the gross size reduced
carpet in a slurried wet state until at least after the ash
particles are removed in the water treatment system and the mixed
carpet fiber are separated by being processed through a
centrifuge.
18. The process of claim 17 further comprising the step of
introducing water into the pulper by gravity to bring the solid to
water ratio of the carpet slurry down to about 6% rapidly.
19. The process of claim 17 further comprising the steps of:
cutting the mixed nylon and polypropylene fibers in the carpet
slurry to a sufficiently short length so that the nylon and
polypropylene fibers do not form a bird's nest or are not heated up
to prevent changes to the chemical and physical make-up of the
fibers and are prepared for feed into the centrifuge washing the
mixed nylon fibers and polypropylene fibers to remove residue on
exterior surfaces of the nylon and polypropylene fibers and
separate calcium carbonate from the nylon and polypropylene fibers
for recovery and recycling.
20. The process of claim 19 further comprising the step of
introducing the slurry of cut and washed short length nylon and
polypropylene fibers into the centrifuge to separate the nylon
fibers and the polypropylene fibers.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
patent application Ser. No. 16/749,878, filed on 2020 Jan. 22,
which is a continuation application of U.S. patent application Ser.
No. 15/587,251, filed on 2017 May 4, now U.S. Pat. No. 10,576,478,
which is a continuation application of U.S. patent application Ser.
No. 15/346,598, filed on 2016 Nov. 8, now U.S. Pat. No. 9,676,917,
the entire contents of which are expressly incorporated herein by
reference.
STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT
[0002] Not Applicable
BACKGROUND
[0003] The various aspects described herein related to an advanced
manufacturing process and plant to recycle carpet.
[0004] Homes and businesses utilize carpet. These include
residential broadloom carpet which has a taller pile and looser
loop design and commercial broadloom carpet which has a short pile
with a tight loop to withstand heavy foot traffic. Carpet is
primarily made up of a face fiber (e.g. nylon or polyester),
backing material (e.g. polypropylene), a filler (e.g. calcium
carbonate) and an adhesive to bind the face fiber with the backing
material (e.g. SBR latex). Post-consumer carpet (PCC) also has dirt
from the carpet use.
[0005] When the carpet needs to be replaced, the carpet is
discarded and fills the landfills or is sent to waste-to-energy
facilities. There is also "pre-consumer carpet waste," also known
as "post-industrial carpet" (PIC) waste which has not been
installed for consumer use. This includes carpet manufacturer
trimmings, rejects, and overruns. Unless otherwise indicated, the
use of the term PCC includes the ability to process PIC.
[0006] Efforts have been made to recover materials from PIC and
residential PCC for recycling into other products but there are
certain deficiencies in doing so. These efforts do not include the
processing of commercial broadloom carpet which has unique
recycling challenges. Additionally, these efforts primarily attempt
to recover the face fiber (and sometimes the backing fiber) but not
the calcium carbonate, SBR latex adhesive composite and dirt,
collectively known as "ash" which is sent to landfills and thus
losing over 40% of the amount of the PCC material that is actually
recycled.
[0007] One common recycling method is shearing the face fiber pile
from the surface of residential PCC. This approach only recovers
the face fiber that extends above the carpet backing. It is labor
intensive and not effective in recovering the significant portion
of the face fiber found below the backing. The remaining material,
commonly referred to as the carpet carcass is either disposed in
landfills or sent to waste to energy facilities. There have been
some attempts to also process the carcass material, however, these
have similar deficiencies as that of processing whole carpet.
[0008] Other common methods attempt to recover the face fiber by
processing the whole carpet. These methods include preparing a
slurry of the size-reduced mixed fiber into a liquid medium and
then separating it using a centrifuge. However, producing the
size-reduced mixed fiber from the whole carpet and removing the
nodules of calcium carbonate and SBR latex adhesive attached to the
face fiber is done through numerous dry processing steps prior to
slurrying the fiber and using screens to cut the fiber to shorter
lengths This method has certain deficiencies including problems
controlling the excessive particulate (i.e. dust) emissions that is
generated from the numerous dry processing steps. These airborne
particulates can impact worker health and ambient air quality.
[0009] Accordingly, there is a need in the art for an improved
method of recycling carpet.
BRIEF SUMMARY
[0010] A plant and process for recycling carpet is disclosed
herein. The method processes the carpet in an aqueous environment
in order to minimize and control the particulates and dust
generated through the size-reduction process and the efforts to
release and remove the nodules of calcium carbonate and SBR latex
adhesive composite from the backing that is attached to the face
fiber. Processing under water also increases the amount and the
quality of nylon fiber recovered and allows for cost-effective
recovery of polypropylene backing fiber and calcium carbonate which
has previously been considered a waste. Nylon fiber may be either
nylon 6 or nylon 6,6 dependent on the type of nylon in the face
fiber of the processed carpet. Additionally, it allows for the
recycling of reclaimed material from commercial broadloom carpet
that previously could not be recovered using other methods.
[0011] The plant reduces the carpet in relation to an initial
"gross" size reduction step in a dry state that reduces the whole
carpet to carpet squares ranging from 2'' by 2'' to 12'' by 12''
and more preferable between 4'' by 4'' to 8'' by 8'' utilizing a
single shaft shredder. Thereafter, the "gross" sized reduced carpet
squares are reduced into size-reduced mixed fiber of nylon face
fibers and polypropylene fabric backing fibers in an aqueous state.
The particulate and dust generated from this "gross" size reduction
is minimized because the shredder is not used to reduce the carpet
to small pieces and particles (less than 0.5 square inches in
size). The reduction of the carpet squares to a size-specific fiber
is done under water using a wet pulper and a wet refiner operated
in series. The minimized particulates and dust that is generated by
the shredder for gross size reduction is controlled by (1) point
source emission controls (dust collection integrated into the
design of the machine and attached directly to the
machine--collects the majority of all generated dust), (2) general
area dust collection (unattached dust collection hoods located over
a targeted machine) and (3) by the dust collection equipment
designed into the dry processing room that collects any low levels
of dust not captured by the machine associated equipment. The
particulates and dust collected from all three methods may be
discharged into the wet pulper to allow for the recovery of this
material for recycling. To additionally ensure protection of
employee health and prevent emission of particulates to the
environment in the case of an upset condition, the dry gross size
reduction process is conducted in a room separate from the wet
process.
[0012] In addition to controlling particulate emissions, processing
the carpet in an aqueous environment allows for (1) enhanced
removal of the calcium carbonate/SBR latex nodules, (2) multiple
washings to produce cleaner fiber, (3) cutting of fiber underwater
to enhance fiber separation and increase polypropylene recovery,
(4) capturing emissions from the dry processing step as reclaimed
product, (5) removal of ash (i.e. the combined term for calcium
carbonate, SBR and dirt) prior to fiber separation to reduce
processing costs and improve quality of recovered nylon and (6)
maximizing the amount of recovered material (product) for use as
recycled content/raw material for manufacturing. The following
expands on the elements of the process:
[0013] The room in which the carpet is reduced in size to about
4''.times.4'' to 8''.times.8'' controls emissions and mitigates
potential impacts from the particulate emissions from the carpet
gross reduction process by, starting from the most important first
(1) the shredder just needs to reduce the material to about
4''.times.4'' squares to 8'' by 8'' squares (not down to the fiber
as is the case for other method which combine the shredder with a
granulator and/or a hammer mill to produce the fiber in the dry
state) therefore, less calcium carbonate and dirt is produced and
(2) the next level is point source removal of the particulates that
we've minimized by (1), finally (3) the separation of the room is
just for minimizing noise in the rest of the plant and in case we'd
have an upset condition. See discussion above for the three types
of dust collection used in the plan. In normal operating
conditions, this room will seem to be dust free.
[0014] The plant reduces the size of a large format carpet (e.g.
room sized carpet) to about 4'' by 4'' to 8'' to 8'' in size with a
shredder. The shredder and other dry processing equipment is
located within a dry processing room or a controlled environment
which captures any low levels of airborne particulates caused by
the shredder or other dry processing equipment and that might
pollute the surrounding area and the environment. The airborne
particulates are captured and transferred into the wet pulper for
processing through the plant. Moreover, the gross size reduced
carpet squares from the shredder is placed in the wet pulper to
break down the carpet into its various components (e.g. nylon
fiber, polypropylene fiber and calcium carbonate). The wet pulper
may be located outside of the dry processing room but at this
point, the process is all underwater and the nylon fiber,
polypropylene fiber and calcium carbonate remain wet (e.g. mostly
greater than 80% moisture but always greater than 15% moisture)
until the nylon fiber and polypropylene fiber are dried and
pelletized, and packaged for recycling and sold to a buyer. The
recovered calcium carbonate product will be sold with the moisture
content retained from the processing. By locating the shredder and
other dry processing equipment in the dry processing room, any
airborne particulates from the equipment is safely collected and
does not cause an environmental, employee health or safety issue.
Moreover, the collected airborne particulates are introduced into
the wet pulper so that any nylon fibers, polypropylene fibers,
calcium carbonate, adhesive components, dirt and debris from the
trapped airborne particulates can be recycled and not thrown away.
Moreover, after any material to be recycled leaves the dry
processing room the process places it in water or keeps it at a
high moisture content to prevent any airborne particulates which
can cause worker health and ambient air quality problems. The
process also uses a wet pulper to process the gross size-reduced
carpet squares to a mixed fiber and remove the calcium
carbonate/SBR nodules and two subsequent washing systems to wash
the mixed fiber. The system also cuts the nylon fibers and
polypropylene fibers underwater to a short enough length to fully
separate the fibers from the rest of the carpet composite; prevent
the fibers from forming a bird's nest that can act to hold the
fibers together; helps release the calcium carbonate and other
carpet ash components that was liberated in the wet pulper that
might be trapped within the fibers when long and formed into the
bird's nest; prepare the fibers for effective separation by the
centrifuge. Washing the short nylon and polypropylene fibers
removes the remaining calcium carbonate and other ash components
from the exterior surface of the fibers so that the nylon and
polypropylene fibers after they are separated have a high degree of
purity.
[0015] More particularly, a carpet recycling plant for separating
nylon fibers, polypropylene fibers and calcium carbonate from
carpet is disclosed. The plant may comprise an air controlled room
which retains dust and other particles; a shredder for gross
reduction of whole carpet to carpet squares sized to about
4''.times.4'' to about 8''.times.8'', the shredder and associated
dry processing equipment located within the air controlled room so
that the air controlled room captures and processes airborne dust
and other particulates emitted from carpet processed through the
shredder and other dry processing equipment; a water-based pulper
which receives the gross size reduced size carpet composite and
further breaks down the carpet to form a carpet slurry; an air
exhaust of the air controlled room in fluid communication with a
water based pulper to route the dust and other collected
particulates from the air controlled room to the water based
pulper; a water based refiner to chop the mixed nylon and
polypropylene fibers in the slurry to a short, controlled length;
water based washing operations to clean the mixed fibers; and a
centrifuge receiving the clean slurry of mixed fibers. After the
carpet and the ash and other particulates enter the wet pulper, the
ash and other particulates and carpet fiber remain wet until the
mixed carpet fiber is processed and separated through the
centrifuge. The calcium carbonate and other ash components are sold
without removing the moisture from processing.
[0016] The nylon fibers and the polypropylene fibers may remain
above 40% moisture after introducing the carpet and the other
particles into the wet pulper and before being outputted of the
centrifuge.
[0017] The plant may further comprise a water storage tank for
recycled water. The water storage tank may be positioned at a
higher elevation compared to the wet pulper so that water from the
water storage tank is introduced into the wet pulper and other
processing equipment by gravity feed.
[0018] The water from the storage tank may be introduced into the
wet pulper so that the slurry of the carpet and ash particles have
a ratio of about 6% solids with the rest being water.
[0019] The plant may further comprise a first washer and de-water
unit wherein the carpet slurry is processed through the first
washer and de-water unit to remove the calcium carbonate, other ash
materials from the slurry of mixed fibers of nylon and
polypropylene after being processed through the wet pulper.
[0020] The plant may further comprise a water treatment area. The
calcium carbonate, other ash materials and water from the first
washer and de-water unit may be transferred to the water treatment
area to remove the water from the calcium carbonate so that the
calcium carbonate is greater than 30% calcium carbonate and the
water is cleaned and returned to a water storage tank which feeds
water into the wet pulper and other wet processing equipment.
[0021] The plant may further comprise a refiner. The slurry of
mixed fibers of nylon and polypropylene may be cut under water to a
short length in the refiner so that the nylon fibers and
polypropylene fibers in the slurry do not form a bird's nest
configuration and are prepared for processing in the
centrifuge.
[0022] The mixed nylon fibers and polypropylene fibers in the
slurry may be cut to about 5 mm long.
[0023] The plant may further comprise a second washer and de-water
unit which receives the slurry of the short length nylon and
polypropylene fibers and agitates the nylon and polypropylene
fibers to remove residue and other material on an exterior surface
of the nylon and polypropylene fibers and further separate calcium
carbonate, other ash materials and water from the nylon and
polypropylene fibers. The separated calcium carbonate, other ash
materials and water may be transferred to a water treatment area to
remove the water from the calcium carbonate so that the calcium
carbonate is greater than 30% calcium carbonate and the water is
cleaned and returned to a water storage tank which feeds water into
the wet pulper and other wet processing equipment.
[0024] The plant may further comprise a centrifuge feed tank which
receives the slurry of the clean nylon and polypropylene fibers
from the second washer and de-water unit and receives additional
water to reduce the solids percentage in the fiber slurry to about
2% solids.
[0025] The plant may further comprise a two stage centrifuge that
receives the slurry of nylon and polypropylene fibers that may be
maintained at a 2% solids ratio with water and separates the nylon
fibers from the polypropylene fibers. The centrifuge may be a two
stage centrifuge. It is also contemplated that the centrifuge may
have other suitable configurations.
[0026] The plant may further comprise a polypropylene de-water unit
that receives the polypropylene fibers from the centrifuge to bring
a moisture content of the polypropylene fibers down below 30% and a
polypropylene fiber dryer to bring the moisture content of the
polypropylene fibers down to about 3% water.
[0027] The plant may further comprise a nylon fiber dryer that
receives the nylon fibers from the centrifuge to bring the moisture
content of the nylon fibers down to about 3% water.
[0028] In another aspect, a process of recycling carpet to separate
nylon fibers, polypropylene fibers and calcium carbonate from the
carpet is disclosed. The process may comprise the steps of
receiving carpet in an air controlled room; introducing carpet into
a shredder which is located in the air controlled room; trapping
ash and other particulates emitted from the shredder within an air
controlled room; transferring the trapped ash and other
particulates from the air controlled room to a wet pulper which is
located outside of the air controlled room; transferring gross
sized reduced carpet outputted from the shredder into the wet
pulper; maintaining the ash and other particles and the gross
reduced sized carpet in a wet state slurry until at least after the
ash and other particles are substantially removed and the carpet
fibers are processed through a centrifuge.
[0029] The process may further comprise the step of introducing
water into the wet pulper by gravity to bring the solid to water
ratio of the carpet slurry down to about 6% rapidly.
[0030] The process may further comprise the steps of cutting mixed
nylon and polypropylene fibers in the carpet slurry to a
sufficiently short length so that the nylon and polypropylene
fibers are prepared for processing by the centrifuge and do not
form a bird's nest; and washing the nylon fibers and polypropylene
fibers to remove residue and other material on exterior surfaces of
the nylon and polypropylene fibers and separate calcium carbonate
and other ash components from the nylon and polypropylene
fibers.
[0031] The process may further comprise the step of introducing the
cut and washed short length nylon and polypropylene fibers into the
centrifuge to separate the nylon fibers and the polypropylene
fibers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a flowchart of a carpet recycling process;
[0033] FIG. 2 is a flowchart of a water treatment process of the
carpet recycling process;
[0034] FIG. 3 is a perspective view of the carpet with the cut
pile;
[0035] FIG. 3A is a perspective view of the carpet with a looped
pile;
[0036] FIG. 4 is a schematic diagram of a dry processing room
including a shredder;
[0037] FIG. 5 is a schematic diagram of a wet pulper and a refiner
with washer and dewater units;
[0038] FIG. 6 is a schematic diagram of a centrifuge;
[0039] FIG. 7 is a schematic diagram of a polypropylene fiber
dryer;
[0040] FIG. 8 is a schematic diagram of the nylon fiber dryer;
and
[0041] FIG. 9 is a schematic diagram of the water treatment process
shown in FIG. 2.
DETAILED DESCRIPTION
[0042] A carpet recycling plant 22 and process 10 of recycling
post-consumer carpet to separate nylon fibers, polypropylene
fibers, calcium carbonate and other materials within a carpet 20 is
disclosed herein. The carpet 20 is initially processed in a dry
processing room 32 to reduce the size of the carpet 20 to about 4''
by 4'' to about 8'' by 8'' from a larger format (e.g. room sized
carpet). The dry processing room 32 is an air controlled room so
that dust and other particulate materials produced from the
reduction process (i.e. shredder 28) and other dry processing
equipment does not escape into the environment and cause an
environmental, employee health or safety issue. The reduced size
carpet is transported and put into a wet pulper 34 which may be
located outside of the dry processing room 32. Dust and other
particulates produced by the reduction process may collectively
contain nylon fibers, polypropylene fibers, calcium carbonate and
household dirt. The dust and other particulate matter is introduced
into the wet pulper 34 in order to capture the fibers and calcium
carbonate and recycle the same. Once the dust and other particulate
matter and the reduced size carpet is introduced into the wet
pulper 34, the rest of the processes is performed in a wet state or
underwater so that the small particles do not become airborne. If
some of the particulates do become airborne, dust accumulators 88
may be positioned at key locations in order to capture the
particulates. The particulates may be reintroduced into the wet
pulper 34 to recycle fibers and calcium carbonate that might make
up the dust particles. The plant 22 and process 10 efficiently
separates the nylon fibers, polypropylene fibers and recovers the
calcium carbonate so that individually, the nylon fibers and
polypropylene fibers have a high purity content (i.e. above 90%,
and more preferably above 98%). The plant 22 and the process 10
also manages emissions of particulates that if introduced into the
workspace or the atmosphere would cause respiratory problems and
other issues for those people that might inhale the particulates
and also contribute to local air pollution and global warming.
[0043] More particularly, referring now to FIG. 1, a block flow
diagram showing the carpet recycling process 10 is shown. When a
homeowner or business replaces carpet, the old carpet is removed
when the new carpet or other types of flooring is installed in its
place. The removed carpet includes both residential broadloom
carpet which typically has a taller pile and looser loop design and
commercial broadloom carpet which has a short pile with a tight
loop to withstand heavy foot traffic. The various components of the
old carpet may be separated and then recycled in order to minimize
or eliminate waste from the old carpet being disposed in landfills
or sent to waste to energy facilities. The recycling of the nylon
and polypropylene components of the old carpet also replaces virgin
raw material produced from refining petroleum thus reclaiming this
material from old carpet also saves petroleum resources and
eliminates the greenhouse gas emissions released through producing
the virgin nylon and polypropylene material. Although the carpet
recycling process 10 is being described in relation to an old used
carpet which has exceeded its lifespan, the carpet recycling
process 10 may be used to recycle new carpet that might be no
longer useful, remnants, or other reasons that might render the new
carpet unusable. The process may be used to recycle some or all of
the components that are used to manufacture carpet (e.g. carpet
manufacturer trimmings, rejects, and overruns).
[0044] The carpet 20 being recycled may have a nylon face fiber
with a woven polypropylene primary backing 16 into which is tufted
the nylon face fibers 14. The backing system also 18 glues and
adheres the nylon face 14 and polypropylene primary backing 16
together. The backing adhesive system may contain styrene butadiene
rubber (SBR) and calcium carbonate as a filler. A large percent of
the backing system 18 is comprised of the calcium carbonate.
Accordingly, the following discussion of separating the backing
system 18 (which includes the polypropylene primary backing fiber
16) from the nylon face 14 may also be placed in the context of
separating the calcium carbonate and the SBR (i.e., backing system,
ash) from the nylon face 14 and the polypropylene primary backing
fiber 16. However, such language and discussion should also be
applied to separating the ash components of the backing system 18
from the nylon face 14 and the polypropylene primary backing fiber
16.
[0045] The process 10 reclaims all three main components, namely,
the nylon face which is either nylon 6 or nylon 6,6 fiber dependent
on the type of carpet processed, the polypropylene used for the
primary backing which is fabricated from polypropylene fiber and
the backing system 18 which is comprised of an SBR adhesive system
containing calcium carbonate filler. The backing system 18 when
being separated from the nylon face 14 and the polypropylene
primary backing 16 may also be referred to as ash or calcium
carbonate since calcium carbonate is a major component of the
backing system 18.
[0046] The carpet to be recycled may be provided to a carpet
recycling plant in a baled format. The preferred format is baled
carpet but other formats are also possible including but not
limited to loose carpet. In either case, nylon face fiber carpet
needs to be sorted out from other face fibers types using a Near IR
(NIR) spectroscopy handheld analyzer (or other analyzer) and
additionally separated into nylon 6 and nylon 6,6 carpet bales
which is processed separated. The loose carpet may be any size from
small pieces (i.e., >12''.times.12'') up to a room size carpet
or rolled unused carpet. Carpet 12 may be collected at a carpet
recycling plant 22 or at a carpet collection/sorting facility and
stored 24 on-site or off-site. The baled carpet 12 is unbaled and
may be inspected 26 to ensure that the carpet 12 is processed with
other carpet 12 of similar characteristics (e.g. nylon 6 vs. nylon
6,6) and that no foreign objects are within the carpet 12 and that
it is suitable to be inserted into a shredder 28. After the carpet
12 is inspected, the carpet 12 is placed on a shredder feed 30
which transfers the carpet 12 into the shredder 28 located in a dry
processing room 32. The dry processing room 32 contains and
controls all of the dust and particulates produced by the shredder
28 which reduces the carpet 12 to a size of approximately 4'' by
4'' to 8'' by 8''. The carpet in the baled carpet 12 may be larger
than that size and be uncut from a large room size carpet size. The
baled carpet 12 may be brought into the dry processing room 32 with
a forklift or pallet jack, unbaled and then loaded onto the
shredder feed conveyor 30 by hand or by mechanical means.
[0047] The shredder feed 30 introduces the carpet 12 into the
shredder 28 to reduce the carpet to a size of approximately 4'' by
4'' to 8'' by 8''. This process of gross size reduction of the
carpet in the shredder 28 produces airborne particulate dust. This
dust is contained both by equipment attached to the shredder 28 and
in the dry processing room 32. The dry processing room 32 is an air
controlled room that does not allow particulates from inside the
room to escape out of the room and into the environment. Dust may
be comprised of nylon fibers, polypropylene fibers, calcium
carbonate and other materials comprised of the backing system 18
and household dirt. Some of the dust will be suspended in air as
airborne particulates and some of the dust will also be too heavy
and fall to the ground. The dry processing room 32 may have a
general area dust collection 88 which collects the airborne
particulates and introduces that dust into an air separator 35 (see
FIG. 5). Additionally, the dust that falls to the ground may be
swept up or vacuumed up and introduced into the wet pulper 34. The
dust that is suspended in air and the dust that falls to the ground
is introduced into the wet pulper as shown by process line 36 (see
FIG. 1). Also, the shredder feed 30, shredder discharge 38, carpet
weighing 40 and the pulper feed conveyor 42 may have a dust
collection unit which routes the dust to the pulper 34. Solid waste
from unauthorized materials in the carpet bales may be generated
and removed from the dry processing room 32 at a rate of about 80
pounds per hour and 22 pounds per hour from the shredder 28. The
solid waste may be introduced into the pulper 34 or sent to a
landfill or another recycler
[0048] Dust collected with the general area dust collection 88 is
sent to the dust separator 35 shown in FIG. 5. The dust separator
35 also may internally recycle the air so that no air is outputted
from the plant. The dust separator 35 separates the dust containing
nylon fibers, polypropylene fibers, calcium carbonate and other
material and introduces the dust into the wet pulper 34. From the
shredder 28, gross size reduced carpet is outputted from a shredder
discharge 38. The gross size reduced carpet may be transported in a
transport box 90 and transported to the wet pulper 34 or placed on
a belt or pneumatic or other conveyor which transports the gross
size reduced carpet to the wet pulper 34. The conveyor system may
also include a weighing system.
[0049] In order to introduce the dust suspended in air and dust
that falls to the ground into the wet pulper 34, that dust along
with the gross size reduced carpet exiting from the shredder
discharge 38 may be weighed 40. The dust and the gross size reduced
carpet are introduced into the wet pulper 34. Water from a recycled
water storage tank 94 is also introduced into the wet pulper so
that the slurry mixture in the wet pulper 34 is at about 6% solids
with the rest of the slurry being water. The 6% target percentage
of the slurry is preferred but may be between less than 1% and 15%.
The amount of water introduced into the wet pulper 34 from the
recycled water storage tank 94 is performed at a high rate of
transfer. To achieve such a high rate of transfer, the recycled
water storage tank 94 may be placed at an elevation higher than the
wet pulper 34 so that the water from the recycled water storage
tank 94 may be gravity fed into the wet pulper 34. The wet pulper
34 is a batch process. However, a continuous process is also
contemplated. As such, gross size reduced carpet and dust
particulates from the dry processing are introduced into the wet
pulper 34 and water from the recycled water storage tank 94 is
introduced into the wet pulper to achieve a target percent solid in
the slurry. Since it is a batch process and the wet pulper 34 is
large, a large amount of water is required (e.g. 2000 gallons per
batch). Hence, the gravity feed aids in maximizing the speed at
which water is introduced into the wet pulper 34. The dust and the
gross sized reduced carpet are now underwater and may be cut up and
shredded to complete the primary size reduction underwater and to
completely disassemble the nylon face fiber, polypropylene primary
backing fiber, secondary backing system 18 and other materials from
each other. Any dust particles produced from the process of
completely disassembling the nylon face 14, polypropylene primary
backing fiber 16 and the secondary backing system 18 remain in the
water to prevent any particulates that might be generated in the
pulping process to remain in the water and eliminate dust from
escaping into the plant or to the atmosphere. The tank and the wet
pulper 34 are placed outside of the dry processing room 32. The
dust, other materials and gross size reduced carpet may be
introduced into the wet pulper 34 via the transport box 90 or a
pulper feed conveyor 42.
[0050] The recycled water storage tank 94 may be filled with about
50,000 gallons of water. Most of the water that is used in the
process 10 is retained in the process 10 and is recycled and
cleaned and transferred back into the recycled water storage tank
94. By way of example and not limitation and as discussed herein,
water used in the system is treated as shown in FIG. 2 then put
back into the tank 94. Water is introduced into the tank and a rate
of about 3 gallons per minute to replace any loss of water from the
process 10 due to evaporation, product moisture (primarily in the
calcium carbonate) and other minor losses. However, the 3 gallons
per minute introduction of new water into the tank 94 is all that
is needed in order to maintain the process 10.
[0051] The operation of the wet pulper 34 may be a batch operation.
When the wet pulper is running a batch, a pump motor 96 is off.
Also, a three-way valve 37 directs the circulating flow back into
the wet pulper 34 tank. The wet pulper 34 completes the size
reduction underwater and disassembles the nylon face fiber,
polypropylene primary backing fiber, the other backing system
materials 18 and all the materials from each other. and circulates
the carpet slurry until the required disassembly has been
accomplished with the wet pulper 34. Once the wet pulper 34 has
completed the size reduction and disassembly of the carpet
components, the three-way valve 37 is activated to direct the
slurry to the washer and dewater unit 44 and the pump 96 is turned
on so that the pulped carpet (i.e., carpet slurry) may be
introduced into the washer and dewater unit 44.
[0052] The wet pulper 34 may be a batch process. It may process
about 1072 pounds of gross size reduced carpet per batch which
would require about 2000 gallons of water to achieve a 6% solids
ratio between the carpet that has been further sized reduced in the
pulper water to produce the carpet slurry. However, other ratios
between the pounds of size reduced carpet and gallons of water are
also contemplated to achieve other than 6% solids ratio in the
carpet slurry.
[0053] Carpet is fabricated in order to be very durable and
resilient to daily wear and use. To this end, the nylon face fiber
or yarn 14 is tufted into the polypropylene primary backing 16 as a
U-shaped cut-pile fiber or as a continuous loop fiber. The face
fibers extend upward from one side of the polypropylene primary
backing 16 and the bottom of the tufted fiber is contained on the
other side of the polypropylene primary backing 16. In order to
hold the tufted fiber to the polypropylene primary backing 16, the
bottom is adhered to the polypropylene primary backing 16 by an
adhesive system that may contain styrene butadiene rubber (SBR) and
calcium carbonate as a filler. This adhesive, the bottom portion of
the tufted face fiber and some portions of the polypropylene
primary backing and the calcium carbonate is referred to as a
nodule and is very hard to remove and disassemble so that the nylon
face fiber 14, polypropylene fiber 16 and the backing system 18
(i.e. the calcium carbonate, SBR and household dirt collectively
called ash) are completely disassembled to the extent that will
allow them to be separated from each other and recycled.
[0054] The wet pulper 34 is an aqueous based pulper and very
effective in removing nodules completely so that the mixed nylon
and propylene fibers can be separated from the backing system 18.
The wet pulper 34 produces a slurry made up of the components of
the size reduced, pulped carpet. The dilute carpet slurry is pumped
out of the wet pulper 34 and is introduced into a washer and
dewatering unit 44. The washer and dewatering unit may be a
motorized horizontal rotating drum with holes around the drum. The
carpet slurry which is comprised of 94% water with the remaining 6%
being solids consisting of the mixed nylon and polypropylene fibers
and the carpet ash (i.e. the calcium carbonate, SBR and household
dirt) is dropped into the center of the drum. Water spray bars
located inside the drum wash the carpet slurry as it passes through
the drum. The mass of water, mixed fibers and the ash from the
carpet backing is turning and being washed at the same time due to
the turning of the drum. The inside surface of the drum cylinder is
supplied with diverters that move the carpet slurry down the length
of the drum. The mixed nylon and polypropylene fibers remain inside
the drum, and the water along with the carpet ash (i.e. calcium
carbonate and other non-fiber solid material) pass through the
holes of the drum and are collected and transferred into a
collection tank which is pumped to the water treatment process
shown in FIG. 9. The fibers retained in the drum include the mixed
nylon fibers and polypropylene fibers. Some of the carpet ash from
the backing system 18 are retained in the drum because some of the
nylon and polypropylene fibers can be very long and are tangled to
each other and form a bird's nest configuration which traps the
calcium carbonate of the backing system 18. The wash and dewatering
unit 44 is a gross separator and separates and removes most of the
calcium carbonate and the other components of the backing system 18
from the fibers of the nylon face 14 and the polypropylene primary
backing fiber 16.
[0055] The nylon fibers and the polypropylene fibers are generally
between about 10 mm to 100 mm in length but also small amounts of
fibers i.e. fines <10 mm may be included. The wet pulper 34
further reduces the gross size reduced carpet which is introduced
into the wet pulper 34 at a size of about 4'' by 4'' to 8'' by 8''
down to mixed size-reduced nylon face fibers and size-reduced
polypropylene primary backing fibers; and initiates the separation
of the mixed nylon and polypropylene fibers from the calcium
carbonate and other ash materials (i.e. adhesive and dirt). The
mixed nylon and polypropylene fibers may have a length between 10
mm to 100 mm but may have a portion of fibers having a length less
than 10 mm. Additionally, the mixed nylon and polypropylene fibers
and any calcium carbonate trapped within the fibers are at about
50% solids when exiting the washer and dewatering unit 44.
[0056] In the pulper wash and dewater unit 44, the mixed fibers may
be cleaned by the action of internal water sprays in the rotary
drum screen and by the rubbing of the fibers against each other
acting to remove the ash, residue and adhesive from the surface of
the fibers. This may remove the calcium carbonate and other ash
materials for collection and recycling and cleans the mixed fibers.
This unit may be the same as the wash and dewater unit after the
refiner but with a 2 mm screen size. It is also contemplated that
the wash and dewater unit 44 may be removed from the process so
that the pulped carpet slurry is transferred to the refiner 46
without processing by the wash and dewater unit 44.
[0057] The mixed nylon fibers and the polypropylene fibers and
remaining calcium carbonate and other ash components are introduced
into a refiner feed tank 46 at about 50% solids and 50% water.
Additional water is introduced into the refiner feed tank 46 to
achieve a slurry of about 2.5% solids ratio with water by weight.
Although the stated preferred target for the slurry is 2.5% solids,
water may be introduced in order to achieve a percentage of about
2% to about 5%. The percent solid for the slurry for the refiner is
less than the target percent solids for the wet pulper slurry but
greater than the percent solids for the slurry in the centrifuge
feed tank 54 discussed below. A refiner/chopper 48 reduces the
length of the mixed fibers of the nylon and polypropylene to a
consistent size of about 5 mm plus or minus 1 mm. The mixed fibers
are introduced into the refiner feed tank and process water is also
introduced in order to bring the slurry mixture of the water and
fiber to about 2.5% solid. 90% or more of the calcium carbonate and
the components of the backing system 18 was removed at the wash and
dewatering unit 44. The wash and dewatering unit 44 may have a
rotary drum 2 mm screen size. At this point, the mixed fiber looks
clean but there is still calcium carbonate and other ash components
mixed with the fibers. Non-calcium carbonate ash components may be
adhesive, household dirt, soap, carpet treatments, etc. Moreover,
by reducing the size of the mixed fibers to 5 mm, the fibers are no
longer bunched up into a bird's nest configuration and therefore do
not function as a filter trap that traps loose ash but rather the
loose ash can now be released through the action of the internal
water sprays in the rotary drum screen and by the rubbing of the
fibers against each other. The released loose ash (e.g. primarily
calcium carbonate) is transferred with the wash water to the
collection tank.
[0058] The water and mixed fiber cut by the refiner are introduced
into a second wash and dewater unit 50 which is the same as the
wash and dewater unit after the wet pulper 44 (e.g., 2 mm rotary
drum screen size) except with a smaller rotary drum screen size
(e.g., 1 mm screen size). The rotary drum screen size holes in the
refiner wash and dewater unit are smaller because the mixed fibers
are shorter and the goal is to retain the mixed fibers in the drum
while washing away the majority of the remaining ash.
[0059] The mixed fibers when long (i.e. greater than 1 inch), may
form a bird's nest and act like a filter trap that traps the
ash--including but not limited to calcium carbonate, adhesive and
other materials used in the manufacturing and maintenance of the
carpet during its life such as soap, stain resistant treatment,
etc. When the mixed fibers are short (i.e. about 5 mm long or
less), the fibers no longer form a bird's nest configuration and do
not act like a filter trap. The calcium carbonate and other
materials are released and residue on the fibers themselves now
need to be removed from the fibers. In the refiner wash and dewater
unit 50, the mixed fibers are cleaned by the action of internal
water sprays in the rotary drum screen and by the rubbing of the
mixed fibers against each other acting to remove the ash, residue
and adhesive from the surface of the fibers. This cleans the
fibers. Additionally, during use of the carpet, additional
chemicals may be used on the carpet. By way of example and not
limitation, the carpet may be washed with a soap or stain
resistance chemicals may be applied to the exterior of the fibers.
These chemicals and coatings must be removed from the mixed fiber
in order to increase the purity of the separated fibers when being
recycled. The amount of water and continued agitation from the
refiner wash and dewater unit 50 cleans the fiber. Moreover,
agitation of the mixed fibers also removes skin shed by humans left
on the carpet.
[0060] Additionally, by removing the calcium carbonate and other
ash materials on the mixed fibers before introducing the fibers
into a centrifuge 52, the centrifuge is only needed to separate the
mixed fiber and is not required for additional ash removal. This
allows for the use and increases the effectiveness of a two-stage
centrifuge which is significantly less expensive than a three-phase
centrifuge that would be needed if the centrifuge was also used for
equivalent ash removal. Although a two-phase centrifuge is utilized
in the process and plant described therein, it is also contemplated
that multi-phase centrifuges (i.e., 2 or more phases or stages) may
also be utilized.
[0061] Additionally by processing the fibers to be recycled in
water, the fibers do not heat up and cause undue changes to the
chemical and physical make-up of the fibers. As fibers are agitated
against each other and the fibers are cut to smaller and smaller
sizes, the fibers may generate heat and that heat may change the
morphology or crystalline structure of the fiber and other physical
and/or chemical properties of the polymer. However, by processing
the fibers underwater, the water temperature remains below
100.degree. F. and keeps the fibers cool.
[0062] At the refiner wash and dewater unit 50, smaller holes
(i.e., 1 mm screen size) are used in the rotary drum screen so that
the fibers remain within the drum and calcium carbonate, debris and
ash are washed out into the collection tank and subsequently pumped
into the water treatment process that separates the calcium
carbonate from the process water. The rotary drum screen size of
the refiner wash and dewatering unit 50 is smaller than the screen
size of the pulper wash and dewatering unit 44. After the refiner
wash and dewatering unit, the ash has been removed from the mixed
fiber to less than 5% and more preferably less than 1%. The mixed
fibers are introduced into a centrifuge feed tank 54 in a slurry of
about 50% solids. Process water is added back to the fiber slurry
to get to 2% solids. Although the target 2% solids is preferred, it
is also contemplated that water may be added in order to achieve a
percent solids slurry of about 0.5% to 3%. The feed tank 54 is
agitated in order to prevent any settling out of the mixed fibers.
The slurry mixture is introduced into the two-phase centrifuge 52.
In the centrifuge 52, the nylon fibers are separated from the
polypropylene fibers and water. The nylon fibers having a higher
specific gravity than water with the polypropylene fibers having a
lower specific gravity than water enable the nylon and
polypropylene fibers to be separated by a centrifuge. Due to the
removal of the ash prior to the centrifuge and cutting of the fiber
by the refiner, the separation of the mixed fiber by the centrifuge
is extremely effective resulting in nylon fiber with low to no
cross contamination of polypropylene and polypropylene fiber with
low to no cross contamination of nylon. In the case of a two stage
centrifuge, the separated nylon fiber is discharged with a low
water content and the separated polypropylene fibers are discharged
with the bulk of the water. Any small amounts of ash (e.g. <5%
and more preferably <1%) present in the processed material in
the centrifuge are discharged with the nylon fibers.
[0063] The centrifuge feed tank 54 is agitated to prevent settling
of the mixed fibers and prevent clumps of fibers from aggregating
together. In this manner, a consistent heterogeneous mixture is
introduced into the centrifuge 52.
[0064] The centrifuge spins extremely fast so that the nylon fiber
discharged from the centrifuge has about 12%-20% moisture by
weight. The centrifuge spins to simulate higher gravity in order to
accelerate the separation of material with different densities. The
nylon fibers having a higher specific gravity than water with the
polypropylene fibers having a lower specific gravity than water
enable the mixed nylon and polypropylene fibers to be separated by
a centrifuge. In the case of a two stage centrifuge, the nylon is
discharged with a low water content and the polypropylene fibers
are discharged with the bulk of the water. Any small amounts of ash
present in the processed material in the centrifuge are discharged
with the recovered nylon fibers.
[0065] The discharged nylon fiber may be entrained in air and
introduced into the air separator 35 shown in FIG. 8. The nylon
fiber from the centrifuge is placed onto a conveyor which passes
the nylon fibers through a nylon fiber dryer 56. The nylon fiber
may be packaged 58 (e.g., baled) for sale to a buyer. The nylon
fiber may also be extruded into pellets for sale to a buyer.
[0066] The polypropylene fiber is dewatered 60 so that the
polypropylene fibers are brought to about 20% water. The
polypropylene fibers may be dried 62 then packaged 64. The
polypropylene dried fiber may also be extruded into pellets for
sale to a buyer.
[0067] The recovered nylon fiber is about 90% and up to 99.5% pure
nylon fiber and the recovered polypropylene fiber is also about 90%
and up to 99.5% pure polypropylene fibers. This is a high level of
purity that is obtained through the primarily wet recycling process
10 and is also very eco-friendly and protective of employee health
in that the dust is retained and also fed back into the recycling
process by way of process line 36. Additionally, the areas in which
the nylon and polypropylene are dried as shown in FIGS. 7 and 8
will also have a general area dust collector 88. The general area
dust collector 88 is needed since the polypropylene fiber and the
nylon fibers are dry and have a short length. Any disturbance may
cause the fibers to become airborne. The general area dust
collector 88 will collect the airborne fibers and transfer them
back into the wet pulper 34 so that they are also recycled. One or
more general area dust collectors 88 may be located throughout the
plant 22 in order to capture any airborne particulates of nylon and
polypropylene fibers and calcium carbonate. For example, when the
gross size reduced carpet is brought out of the dry processing
room, the gross reduced size carpet may have small particulates
that can be airborne after having settled on the gross reduced
sized carpet. General area dust collectors 88 may be located in the
pathway from the exit of the dry processing room 32 and the wet
pulper 34.
[0068] Referring now to FIG. 1, certain process steps disclose a
water discharge 66. Whenever water is discharged, the discharged
water follows the process shown in FIG. 2. In particular, the
system water discharge 70 is introduced into a rotary drum screen
72. The rotary drum screen 72 retains and separates nylon and
polypropylene fiber and transfers 74 those fibers to the wet pulper
34. The rotary drum screen 72 separates the fiber from the water
which contains calcium carbonate 76 which is transferred to a
storage tank. The water and calcium carbonate 76 is introduced into
a filter presses 78a, b. The filter presses 78a, b separate the
calcium carbonate mixture out of the water. The water 82 is treated
84 (i.e. add chlorine) and returned back into the plant 22 for use
in processing the carpet for recycling. The calcium carbonate is
dropped onto a loading auger and into a bulk trailer and may have a
moisture content of about 50% water. Alternatively, the calcium
carbonate may be box loaded.
[0069] The filter presses 78a, b are batch operations however a
continuous filtration operation may also be used. As such, when
water from the storage tank 76 is introduced into the filter
presses 78a, b, they are introduced sequentially. In this regard,
water may be introduced into filter press 78a and while that filter
press is running, water is not introduced into filter press 78b.
Calcium carbonate is produced from filter press 78a and either
boxed or transferred to the bulk trailer. When the filter press 78a
is done with its batch processing, water is introduced into filter
press 78b. The water is introduced alternatively and sequentially
into 78a and b.
[0070] Referring now to FIGS. 4-9, a schematic diagram of the plant
22 shown. The baled carpet 12 is released from the bales and
introduced into the shredder 28 by placing the carpet on the
shredder feed conveyor 30 by hand. Although the shredder equipment
is used by other methods to shred material such as carpet down to
very small pieces or down to the fiber, for this process the
shredder is used for gross size reduction of whole carpet down to
carpet squares ranging from 2'' by 2'' to 12'' by 12'' and more
preferable between 4'' by 4'' to 8'' by 8.'' A dust accumulator 88
may be installed above the shredder feed conveyor to collect any
dust suspended in air caused by the movement of the carpet. The
shredder 28 may discharge carpet into a gross size reduced carpet
transport box 90 or conveyer. The shredder 28 may also produce dust
and that dust is collected and along with the dust collected by the
dust accumulator is introduced into the wet pulper 34 as shown by
process lines 36
[0071] The carpet may be weighed and introduced into the wet pulper
by way of a feed mechanism 42. The feed mechanism as shown in FIG.
1 is a conveyor but in FIG. 5, the feed mechanism may be a
mechanical means of lifting and batch dumping the gross size
reduced carpet transport box containing the shredded carpet into
the pulper 34. Alternatively, the feed mechanism may be a conveyor
belt which starts and stops and loads batches into the pulper
34.
[0072] As shown in FIG. 4, dust from the shredder and other dry
processing operations is separated by way of a dust separator 95.
The dust separator 35 discharges the dust into the wet pulper 34
which is filled with water so that the slurry of the gross size
reduced carpet and particulates from the dry processing room has a
solid content in water at about 6%. The water is added into the wet
pulper by way of gravity from the recycled water storage tank 94
containing water. The tank 94 may be at a higher elevation compared
to the wet pulper so that water can be rapidly introduced into the
wet pulper by way of gravity. By way of example and not limitation,
about 2000 gallons of water per minute may be added into the wet
pulper 34 per batch.
[0073] The slurry discharge from the wet pulper 34 may be
introduced into the washer and dewater unit 44 located at an
elevation higher than the refiner feed tank 46. The discharge from
the wet pulper 34 is pumped up to the washer and dewater unit 44 by
way of pump 96. The slurry discharge from the washer and dewater
unit 44 is introduced into the refiner feed tank 46 by way of
gravity. A pump 98 may be used to transfer the discharge from the
refiner feed tank 46 to the refiner 48 and also may be used to pump
the slurry discharge to the water from the dewater unit 50 which
may be positioned at an elevation higher than the centrifuge feed
tank 54. The rest of the process may occur at the same level (i.e.
ground-level).
[0074] Referring now to FIGS. 2 and 9, the water treatment process
is shown by way of a flowchart in FIG. 2 and schematically in FIG.
9. The water is treated at the same elevation compared to the water
storage tank 76. Water containing calcium carbonate and other ash
solids is introduced into the fiber screening unit 72 by way of
line 70. Any removed fiber including nylon fiber and polypropylene
fiber is reintroduced into the wet pulper 34 by line 74. The
remaining water containing calcium carbonate and other ash solids
is transferred into the storage tank 76. A pump pumps the water
containing calcium carbonate and other ash materials from the
storage tank 76 alternately into the filter presses 78a and 78b.
The filter presses 78a, 78b and the chemical treatment system 84
produces clean water that is transferred back into the recycled
water storage tank 94 (see FIG. 5). The calcium carbonate is either
boxed or loaded onto a bulk trailer.
[0075] The shredder 28 may be a 3E Machinery; Single Shaft
Shredder; Model WT48150. The wet pulper 34 may be a Bolton Emerson
Tornado; Model 36. The washer and dewatering unit 44 may be a
Parkson Hycor Rotoshear Rotary Drum; Model HRS6096DV; 2 mm screen.
The washer and dewatering unit 50 may be a Parkson Hycor Rotoshear
Rotary Drum; Model HRS6096DV; 1 mm screen. The refiner 48 may be a
Bolton Emerson Claflin; Model 101. The two-stage centrifuge 52 may
be a Andritz; Solid Bowl Decanter Centrifuge, Two Phase; Andritz
Model A7-3.2. The fiber dryers 62, 56 may be a Stalam; RF &
Forced Air Dryer; Model LTRF 60 kW. The filter presses 78a, 78b may
be a Parkson, Plate & Frame Filter Press.
[0076] The plant and process may recycle both cut pile and loop
pile carpet. Moreover, the plant and process may also recycle both
residential and commercial broadloom type carpet. Commercial
broadloom carpet has a shorter pile and is typically not recycled
to recover its fiber and calcium carbonate because current
techniques of recycling carpet do not recover most of the face
fiber and primary backing fiber and is thrown away thereby making
recycling in this matter not cost-effective. Also commercial
broadloom carpet is also in many cases installed using adhesives on
the floor. The presence of this adhesive on the carpet to be
recycled has hindered earlier attempts to effectively and
economically recycle commercial carpet.
[0077] The term "nylon" may be used to describe either nylon 6 or
nylon 6.6 as the reclaimed carpet face fiber and "polypropylene" to
describe the reclaimed carpet primary backing fiber. However, such
a description represents a presently preferred embodiment but is
merely exemplary and non-limiting relative to the fiber type of the
carpet being recycled.
[0078] It is also contemplated that the plant and method may be
used for only size reduction of the carpet, wet pulping and washing
steps for some applications. In these cases, the centrifuge is not
used to separate the mixed fiber.
[0079] It is also contemplated that the method and plant described
herein may be utilized for recycling other commodities that require
size reduction, cleaning and separation of materials.
[0080] The above description is given by way of example, and not
limitation. Given the above disclosure, one skilled in the art
could devise variations that are within the scope and spirit of the
invention disclosed herein. Further, the various features of the
embodiments disclosed herein can be used alone, or in varying
combinations with each other and are not intended to be limited to
the specific combination described herein. Thus, the scope of the
claims is not to be limited by the illustrated embodiments.
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