U.S. patent application number 10/991854 was filed with the patent office on 2005-06-02 for methods for producing recycled pulp from waste paper.
This patent application is currently assigned to Casella Waste Systems, Inc.. Invention is credited to Bohlig, James W..
Application Number | 20050115690 10/991854 |
Document ID | / |
Family ID | 34623203 |
Filed Date | 2005-06-02 |
United States Patent
Application |
20050115690 |
Kind Code |
A1 |
Bohlig, James W. |
June 2, 2005 |
Methods for producing recycled pulp from waste paper
Abstract
The invention provides methods and apparatus for using waste
paper to produce recycled pulp that can be used by the paper
industry. The recycled pulp produced by the methods and apparatus
of the invention can optionally be mixed with virgin pulp to
produce paper or paper-products. The waste paper can be any grade,
including low quality waste paper, such as mixed waste paper or old
newsprint.
Inventors: |
Bohlig, James W.;
(Cuttingsville, VT) |
Correspondence
Address: |
WILMER CUTLER PICKERING HALE AND DORR LLP
THE WILLARD OFFICE BUILDING
1455 PENNSYLVANIA AVE, NW
WASHINGTON
DC
20004
US
|
Assignee: |
Casella Waste Systems, Inc.
Rutland
VT
|
Family ID: |
34623203 |
Appl. No.: |
10/991854 |
Filed: |
November 19, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60524620 |
Nov 25, 2003 |
|
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|
Current U.S.
Class: |
162/4 ; 162/55;
162/56 |
Current CPC
Class: |
Y02W 30/64 20150501;
D21C 5/02 20130101; Y02W 30/648 20150501 |
Class at
Publication: |
162/004 ;
162/055; 162/056 |
International
Class: |
D21C 005/02 |
Claims
What is claimed is:
1. A method for making recycled pulp comprising: (a) providing
waste material that comprises waste paper and, optionally,
prohibitives; (b) adding the waste material to a liquid-based fiber
separator apparatus; and (c) producing recycled pulp having a
solids content from about 1 wt % to about 85 wt %.
2. The method of claim 1, wherein the recycled pulp has a solids
content from about 1 wt % to about 25 wt %.
3. The method of claim 1, wherein the waste paper comprises a pulp
substitute, a de-inking grade, a brown kraft grade, mixed waste
paper, or a mixture of two or more thereof.
4. The method of claim 1, wherein the waste paper comprises one or
more grades selected from (1); (2); (4); (5); (6); (7); (8); (9);
(10); (11); (12); (13); (15); (16); (17); (18); (19); (24); (21);
(22); (23); (24); (25); (26); (27); (28); (30); (31); (33); (35),
(37); (39); (40); (41); (42); (43); (44); (45); (46); (47); (48);
(49); (50); (51); or a mixture of two or more thereof, wherein the
grade is based on the classification described by Scrap
Specifications Circular 2003, pages 22-25, Institute of Scrap
Recycling Industries, Inc.
5. The method of claim 1, wherein the recycled pulp is relatively
pure recycled pulp.
6. A method for making recycled pulp comprising: (a) providing
waste material that comprises waste paper and, optionally,
prohibitives; (b) adding the waste material to a liquid-based fiber
separator apparatus to produce the recycled pulp; (c) removing
liquid from the recycled pulp to produce recycled pulp that has a
solids content from about 30 wt % to about 85 wt %.
7. The method of claim 6, wherein the recycled pulp has a solids
content from about 45 wt % to about 70 wt %.
8. The method of claim 6, wherein the waste paper comprises a pulp
substitute, a de-inking grade, a brown kraft grade, mixed waste
paper, or a mixture of two or more thereof.
9. The method of claim 6, wherein the waste paper comprises one or
more grades selected from (1); (2); (4); (5); (6); (7); (8); (9);
(10); (11); (12); (13); (15); (16); (17); (18); (19); (20); (21);
(22); (23); (24); (25); (26); (27); (28); (30); (31); (33); (35);
(37); (39); (40); (41); (42); (43); (44); (45); (46); (47); (48);
(49); (50); (51); or a mixture of two or more thereof, wherein the
grade is based on the classification described by Scrap
Specifications Circular 2003, pages 22-25, Institute of Scrap
Recycling Industries, Inc.
10. A method for providing recycled pulp to a paper mill
comprising: (a) providing waste material that comprises waste paper
and, optionally, prohibitives; (b) adding the waste material to a
liquid-based fiber separator apparatus to produce the recycled
pulp, wherein the recycled pulp is in a form that does not need to
be re-pulped for further processing into paper or a paper product;
and (c) transporting the recycled pulp to a paper mill.
11. The method of claim 10, further comprising removing liquid from
the recycled pulp, wherein the recycled pulp is in a form that does
not need to be re-pulped for further processing into paper or a
paper product.
12. The method of claim 10, further comprising storing the recycled
pulp in a container prior to transporting the recycled pulp to a
paper mill.
13. The method of claim 10, wherein the waste paper comprises a
pulp substitute, a de-inking grade, a brown kraft grade, mixed
waste paper, or a mixture of two or more thereof.
14. The method of claim 10, wherein the waste paper comprises one
or more grades selected from (1); (2); (4); (5); (6); (7); (8);
(9); (10); (11); (12); (13); (15); (16); (17); (18); (19); (20);
(21); (22); (23); (24); (25); (26); (27); (28); (30); (31); (33);
(35); (37); (39); (40); (41); (42); (43); (44); (45); (46); (47);
(48); (49); (50); (51); or a mixture of two or more thereof,
wherein the grade is based on the classification described by Scrap
Specifications Circular 2003, pages 22-25, Institute of Scrap
Recycling Industries, Inc.
15. A method for producing a recycled paper product comprising: (a)
providing waste material that comprises waste paper and,
optionally, prohibitives; (b) adding the waste material to a
liquid-based fiber separator apparatus to produce the recycled
pulp, wherein the recycled pulp is in a form that does not need to
be re-pulped for further processing into paper or a paper product;
(c) transporting the recycled pulp to a paper mill; and (d) mixing
the recycled pulp with virgin pulp to produce the recycled paper
product.
16. The method of claim 15, wherein the recycled pulp that is in a
form that does not need to be re-pulped for further processing is
recycled pulp having a solids content of at least about 30 wt
%.
17. The method of claim 16, wherein the recycled pulp has a solids
content from about 30 wt % to about 85 wt %.
18. The method of claim 15, wherein the recycled pulp is relatively
pure recycled pulp.
19. The method of claim 15, wherein the waste paper comprises a
pulp substitute, a de-inking grade, a brown kraft grade, mixed
waste paper, or a mixture of two or more thereof.
20. The method of claim 15, wherein the waste paper comprises one
or more grades selected from (1); (2); (4); (5); (6); (7); (8);
(9); (10); (11); (12); (13); (15); (16); (17); (18); (19); (20);
(21); (22); (23); (24); (25); (26); (27); (28); (30); (31); (33);
(35); (37); (39); (40); (41); (42); (43); (44); (45); (46); (47);
(48); (49); (50); (51); or a mixture of two or more thereof,
wherein the grade is based on the classification described by Scrap
Specifications Circular 2003, pages 22-25, Institute of Scrap
Recycling Industries, Inc.
Description
RELATED APPLICATIONS
[0001] This application claims priority under .sctn. 119 to U.S.
Application. No. 60/524,620 filed Nov. 25, 2003, the disclosure of
which is incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention provides methods and apparatus for using waste
paper to produce recycled pulp that can be used by the paper
industry. The recycled pulp produced by the methods and apparatus
of the invention can optionally be mixed with virgin pulp to
produce paper or paper-products.
BACKGROUND OF THE INVENTION
[0003] Various processes for recovering fibers from waste paper,
such as paperboard food cartons and packages, office waste paper,
magazines and newspapers, have been proposed. Typically, these
recycling processes involve treating the waste paper in a
hydrapulping machine where the fibers are separated by the
agitation of the water, and caustic soda or similar reagents are
used to break down the integrity of the waste paper. These
processes produce a stream of separated fibers which may be passed
through various screening devices to remove prohibitives, and the
resulting slurry containing the fibers may pass through a de-inking
process. After appropriate treatment, the slurry of fibers passes
through a de-watering stage, so that the recovered fibers are
collected in an essentially dry state and packed in bales for
subsequent use in making paper. There remains a need in the art for
new and improved methods and apparatus for recycling waste paper to
produce fibers that can be used in the paper industry. The
invention is directed to this, as well as other, important
ends.
SUMMARY OF THE INVENTION
[0004] The invention provides methods and apparatus to produce
recycled pulp that can be sold or traded to paper mills. The
recycled pulp of the invention can be stored and/or transported in
containers and can be delivered to paper mills by any conventional
method, e.g., truck, train, ship, and the like. Unlike methods
whereby dry bales of recycled fibers are sold or traded to paper
mills which then re-pulp the dry bales of recycled fibers, the
invention provides recycled pulp (i.e., fibers in liquid) which is
in a form that can be easily and readily used by paper mills. The
methods and apparatus of the invention eliminate the steps of (i)
producing a dry bale of recycled fibers, and (ii) re-pulping the
dry bale of recycled fibers. The invention produces recycled pulp
that can be immediately used by the paper industry, either alone or
in combination with virgin pulp, to produce paper and/or paper
products. These and other aspects of the invention are described in
more detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a block diagram of a system or apparatus according
to the invention.
[0006] FIG. 2 is a block diagram of a system or apparatus according
to the invention.
[0007] FIG. 3 is a detail of a fiber separator of the systems or
apparatuses of FIGS. 1 and 2.
[0008] FIG. 4 is a detail of a de-liquefier of the systems or
apparatuses of FIGS. 1 and 2.
[0009] FIG. 5 is a detail of a fiber cleaning system that may be
added to the systems or apparatuses of FIGS. 1 and 2.
[0010] FIG. 6 is a detail of, among other things, a fiber
separator, and a de-liquefier of a system or apparatus according to
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0011] The invention provides methods and apparatus for using waste
paper to produce recycled pulp that can be used by the paper
industry. The recycled pulp produced by the methods and apparatus
of the invention can optionally be mixed with virgin pulp to
produce paper and/or paper products.
[0012] "Pulp" refers to fibers in liquid (e.g., water). The fibers
can be in a liquid slurry, liquid suspension, or the like.
[0013] "Fibers" includes wood-based cellulosic fibers,
nonwood-based cellulosic fibers, natural textile fibers, man-made
fibers, or a mixture of two or more thereof. The term "fibers"
includes natural and man-made fibers that are capable of entrapping
or entraining air within their structure, such as rockwool,
cellulosic fibers, glass fibers and the like.
[0014] "Cellulosic pulp" refers to wood-based cellulosic fibers
and/or nonwood-based cellulosic fibers.
[0015] "Virgin pulp" refers to pulp obtained directly from
trees.
[0016] "Recycled pulp" refers to pulp produced from waste paper.
"Relatively pure recycled pulp" refers to pulp that contains
cellulosic pulp in an amount of about 50% or more; 60% or more; 70%
or more; or 80% or more. In another embodiment, "relatively pure
recycled pulp" refers to pulp that contains cellulosic pulp in an
amount of about 50% to about 99%; about 60% to about 99%; about 70%
to about 99%; about 80% to about 99%, or an amount of about 90% to
about 99%.
[0017] The recycled pulp produced by the methods, systems and
apparatus of the invention is in a form that can be directly used
for further processing by a paper mill without having to be
re-pulped. In one embodiment, the recycled pulp has a solids
content, for example, between about 1 wt % and about 85 wt %. In
the embodiment of the invention that does not use a de-liquefier
(as described herein), the recycled pulp can have a solids content
between about 1 wt % and about 25 wt %; between about 1 wt % and
about 20 wt %; or between about 5 wt % and about 15 wt %. In the
embodiment of the invention that uses a de-liquefier (as described
herein), the recycled pulp can have a solids content between about
30 wt % and about 85 wt %; between about 30 wt % and about 75 wt %;
or between about 45 wt % and about 70 wt %. Because the recycled
pulp of the invention is not dried, it can be immediately used by
the paper mills without having to be re-pulped. Alternatively, it
can be stored and used at a later date by the paper mills without
having to be re-pulped.
[0018] "Prohibitives" include any material which, in excess of the
amount allowed, would make the waste paper unusable as the grade
specified or any materials that may be damaging to the equipment
that processes the waste paper. Scrap Specifications Circular 2003,
page 22, Institute of Scrap Recycling Industries, Inc. (2003).
[0019] "Outthrow" is all papers that are manufactured or treated or
are in such a form as to be unsuitable for consumption as the grade
specified. Scrap Specifications Circular 2003, page 22, Institute
of Scrap Recycling Industries, Inc. (2003).
[0020] "Waste paper" refers to and includes any grade of waste
paper known in the art. Any grade of waste paper known in the art,
including those described herein, can be used in the methods,
systems and apparatus of the invention to produce recycled pulp. An
unexpected advantage of the invention is that any grade, including
low quality grades, of waste paper can be used as a starting
material. The four broad classes of waste paper are (1) pulp
substitutes, (2) de-inking grades, (3) brown kraft grades and (4)
mixed waste paper.
[0021] Pulp substitutes are generally substitutes for chemical
pulps. Chemical pulps are pulp produced by chemical treatments. The
quality of pulp substitutes is most similar to that of virgin
fiber, so their price is also related to virgin fiber (e.g.,
converting and printing trimmings; guillotine shavings (mechanical
and wood free separately); tinteds (suitable for bleaching); and
lightly printed waste paper (e.g.: ledger, ruled book trimmings).
Polycoated board (e.g.: plastic coated liquid packaging board
cartons, footboard, paper plate and cup board) also produces a good
quality pulp, but requires separate initial repulping
treatment.
[0022] Brown kraft grades include, for example, corrugated plant
waste; old corrugated containers; KLS (kraft lined strawboard is
waste-based old corrugated container having more than 33 wt % kraft
linerboard); used kraft sacks; and converting waste. This waste
paper is used mainly for test linerboard and fluting. Old
corrugated container bleaching is used for fine papers.
[0023] Mixed waste paper is the cheapest and lowest quality waste
paper. Traditionally, this has been the balance, after taking out
household waste paper and other grades that are easy to sort. Mixed
waste paper has been used for chipboard and gray back folding
boxboard.
[0024] There has been a continuing degradation in the quality of
old newsprint marketed in the United States. Old newsprint is
usually graded as #6 or #8. The methods and apparatus of the
invention are able to process mixed waste paper, including old
newsprint.
[0025] Household waste is commanding attention as the last major
vein of waste paper to be mined. Called residential mixed paper,
the U.S. recovery rate of the approximately 9 mullion tons per year
is only about 20%. The collection system used determines the
quality of the resulting waste paper. When old newsprint is
collected separately in the United States, the resulting waste
paper composition is approximately 30% carton board/SBS packaging;
30% white grades and mail; 25% mechanical fiber
(news/magazine/coated and uncoated); and 15% brown kraft (bag and
old corrugated containers). This waste paper may be a substitute
for medium quality OCC, with the lower price offsetting the lower
yield.
[0026] Specific grades of waste paper, as defined by Scrap
Specifications Circular 2003, pages 22-25, Institute of Scrap
Recycling Industries, Inc., that can be used as the starting
material to produce the recycled pulp of the invention include: (1)
soft mixed paper; (2) mixed paper; (4) boxboard cuttings; (5) mill
wrappers; (6) news; (7) news, de-inking quality; (8) specialty news
de-inking quality; (9) over-issue news; (10) magazines; (11)
corrugated containers; (12) double sorted corrugated; (13) new
double-line kraft corrugated cuttings; (15) used brown kraft; (16)
mixed kraft cuttings; (17) carrier stock; (18) new colored kraft;
(19) grocery bag scrap; (20) kraft multi-wall bag scrap; (21) new
brown kraft envelope cuttings; (22) mixed groundwood shavings; (23)
telephone directories; (24) white blank news; (25) groundwood
computer printout; (26) publication blanks; (27) flyleaf shavings;
(28) coated soft white shavings; (30) hard white shavings; (31)
hard white envelope cuttings; (33) new colored envelope cuttings;
(35) semi-bleached cuttings; (37) sorted office paper; (39)
manifold colored ledger; (40) sorted white ledger; (41) manifold
white ledger; (42) computer printout; (43) coated book stock; (44)
coated groundwood sections; (45) printed bleached board cuttings;
(46) misprinted bleached board; (47) unprinted bleached board; (48)
#1 bleached cup stock; (49) #2 printed bleached cup stock; (50)
unprinted bleached plate stock; and (51) printed bleached plate
stock. Each grade has specifications on prohibitives and
outthrow.
[0027] Bagasse is an alternative or additional starting material
that can be used in the methods, systems and apparatus of the
invention to make recycled pulp. Bagasse is the cellulosic fiber
separated from the non-fibrous component of plants, such as sugar
from sugar beets or sugar cane and natural rubber from rubber
plants. In the case of sugar cane, bagasse is available in a
bagasse belt around the world parallel to the equator, which
extends from Spain in the North to South Africa and Australia in
the South. Usually, the sugar cane harvesting campaign lasts 4-9
months, which means most pulp mills must carry large stocks of
bagasse. Normally, the bagasse is burned in the sugar mill's
boilers to provide its steam and power requirements. Substitution
of an alternative fuel frees up the bagasse for a pulp mill, but
prices the bagasse at the fuel-equivalent price. Before pulping,
the earth and dirt are washed off, and any magnetic materials
removed. Bagasse can be used in a wide range of paper grades,
including coated papers. The following table shows some typical
levels, which would also apply approximately to other non-wood
pulps, with similar properties (e.g.: fiber length).
1 Bagasse Pulp Grade Paper Grade % Bagasse Bleached mechanical,
Newsprint 75-80 chemimechanical, or Mechanical printing papers 50
thermomechanical pulp: Tissue 50 High yield unbleached Corrugating
medium 75-100 semichemical pulp: Unbleached chemical pulp:
Multiwall sack, extensible 40 Kraft linerboard 40-60 Wrapping paper
(B grade) 50-75 Fruit wrap and tissue 60-90 Glassline and
greaseproof 50-90 Bleached chemical pulp: Printing and writing
papers 80-100 White-lined chipboard, top liner 50 Footboard and
Bristol board 65-75 Fruit wrap and tissue 60-90 Glassline and
greaseproof 50-90 Newsprint 35-50
[0028] It has been unexpectedly discovered that the methods and
apparatus of the invention can be used to process any grade of
waste paper, including law quality grades of waste paper, such as
old newsprint and mixed waste paper. The waste paper used in the
methods and apparatus of the invention can be a single grade or can
be a combination/mixture of two, three, four, five, six, seven or
more different grades of waste paper.
[0029] In FIG. 1, an apparatus 10 for converting waste material
into recycled pulp is shown. The apparatus 10 comprises at least
one fiber separator 12 and, optionally, at least one waste liquid
treater 42 in communication with the fiber separator 12. The fiber
separator 12 is preferably a liquid-based fiber separator, such as
an aqueous based fiber separator. The apparatus 10 can optionally
comprise at least one junk trap 15 and/or at least one ragger 16
for removing prohibitives.
[0030] In FIG. 2, the apparatus 10 comprises at least one fiber
separator 12, at least one de-liquefier 14, and, optionally, at
least one waste liquid treater 42 in communication with the fiber
separator 12 and/or the de-liquefier 14. The de-liquefier 14 is
located downstream from the fiber separator 12 and the de-liquefier
14 is for removing liquid from the recycled pulp. The fiber
separator 12 may be a liquid-based fiber separator, such as an
aqueous based fiber separator. The apparatus 10 can optionally
comprise at least one junk trap (not shown) and/or at least one
ragger (not shown) for removing prohibitives.
[0031] The fiber separator 12 can comprise one or more batch
pulpers and/or continuous pulpers, which are known in the paper
making art. Exemplary conventional fiber pulpers include TA series
pulpers (available from Allimand); Aquabrusher (available from
APMEW or Bellmer); Grubbens pulper (available from Cellwood or
Corner); Barracuda pulper (available from GL&V); Shark pulper
(available from GL&V); HDK Channel pulper (available from Metso
Paper/Fiber); HD Vertical pulper (available from Metso
Paper/Fiber); Preflo pulper (available from Metso Paper/Fiber);
Delta pulper (available from Thermo Black Clawson, Lamont, Aikawa);
Hydrapulper pulper (available from Thermo Black Clawson, Lamont,
Aikawa); St series pulpers (available from Voith Paper); and
Unipulper pulpers (available from Voith Paper).
[0032] While it is preferable to remove the more fragile
prohibitives intact, batch pulping may be used together with a
helical low attrition rotor (resembling an inflated corkscrew) to
minimize prohibitive breakdown. Examples of such equipment include
Bi Pulper (available from A. Celli and Corner); Tri Dyne (available
from GL&V); CHD (Continuous High Density pulper system with
screen for accepts); SMG Pulper (available from Metso Paper/Fiber);
and Helico pulper and Hi Con pulper (available from Thermo Black
Clawson, Lamont). U.S. Pat. No. 4,129,259, the disclosure of which
is incorporated by reference herein in its entirety, is related to
a Hi-Con pulper, available from Thermo Black Clawson.
[0033] The removal of large prohibitives from waste paper may be
achieved by subsystems around the fiber separator 12, such as a
junk trap 15. The junk trap can be used to remove prohibitives
(e.g., stones, metal, and other heavy materials) that can sink into
this dead area of the pulper, between two valves, and is
automatically purged at desired time intervals. A Privet Double
Dumper.TM. is an example of such a junk trap.
[0034] A ragger 16 is also useful for removing prohibitives (e.g.,
baling wire, rags, plastic strips, string, and the like). The
prohibitives entangle each other and may be withdrawn from the
fiber separator 12 as an endless ragger rope by the capstan-like
ragger 16. An example of such equipment includes the Valmet ragger
(available from Metso Paper/Fiber). The rope may be periodically
cut by the ragger rope cutter to facilitate its disposal. An
example of such equipment includes the Valmet tail cutter
(available from Metso Paper/Fiber), Broken ragger tails, weighing
up to 3 tons, can be retrieved from the fiber separator 12 without
emptying it. An example of equipment useful for such operations
includes the Ragger tail grabber (available from Neilsen &
Hiebert Systems).
[0035] Drum pulpers provide an alternative approach to the
conventional pulper. Characteristics of drum pulpers include
continuous operation, minimum degradation of fibers and
prohibitives, and low power consumption (e.g., energy
conservation). Examples of equipment useful for such an operation
include the Fibreflow Drum pulper (available from Andntz-Ahlstrom)
and the Horizontal Drum-Soaking-Mixing-Screening System (available
from Finckh).
[0036] In other embodiments of the invention, the fiber separator
12 can include a secondary pulper downstream from the primary
pulper. The secondary pulper will complement the primary pulper's
ability to take out large prohibitives by removing high and low
density prohibitives, while also deflaking undisintegrated flakes
of paper. The secondary pulper may be either batch or continuous,
and models are available for both batch and continuous primary
pulpers. Examples of secondary pulpers include Selector and
Selepump pulpers (available from A. Celli); Epurex (available from
Corner), ESC series (available from Corner), Turboremover pulpers
(available from Corner); RejectsMaster pulper (available from
Finckh); BeiPurge pulper (available from GL&V); Tamtrap TTP
pulper (available from Metso Paper/Fiber); Dumping Poire
(batch)+Helico pulper=Helipoire System, Poire Pulper (continuous),
Hydra Impactor, Hydrapurge (available from Thermo Black Clawson,
Larrnort); and Contaminex, Fiberizer, and Turboseparator (available
from Voith Paper).
[0037] In other embodiments, the fiber separator 12 of the
invention can include other equipment such as, for example, a fiber
classifier, a dispersion system, a kneading system, and the like.
Examples of dispersion systems include Krima (available from
Cellwood, Corner and FMW), Diskperser (available from GL&V),
Micar Processor, Diva (based on Conflo+HiPreheater fluffer/steam
mixer (available from Metso Paper/Fiber); Frotapulper (available
from MoDoMekan), Triturator/Kneading Disperser (available from
Thenno Black Clawson, Lamort); Disperger (available from Voith
Paper). Examples of kneading systems include MDR Kneader (available
from Andritz-Ahlstrom), Ultra Twin Flyte (available from Thermo
Black Clawson), Kneading Disperger (available from Voith
Paper).
[0038] As shown in FIG. 4, the de-liquefier 14 may include any of
the many types of equipment used for thickening, washing, and/or
separation. For example, the de-liquefier 14 may include a
thickener 25 for increasing the solids content of the recycled pulp
that comes out of the liquid-based fiber separator 1.
[0039] The liquid removed by the de-liquefier 14 may be called
filtrate or pressate (e.g., when from a press). The solid material
from a filter may be called filter cake. A belt filter press can
perform this function. Exemplary belt filter presses include Double
Wire Press (available from Andritz-Ahlstrom); BDP (available from
Baker Process); Turbodrain (1 wire), Winkelpress (2 wires), and
Cascade S {both types in series) (available from Bellmer and
Corner); HC Press, Gap Washer, and TwinWire (with Paraformer
headbox) (available from Metso Paper/Fiber and Phoenix Process
Equipment); Salter Belt Press (available from Salter); DNT Washer
(available from Thermo Black Clawson); Vario Split (available from
Voith Paper); and Osprey (available from William Jones,
London).
[0040] The de-liquefier 14 may include a screw press 40 the may
have either a single screw (e.g., Brown Stock Washing) or double
screw {e.g., two counter rotating intermeshed screws). Examples of
screw presses include: Andritz/Dupps Screw Press (available from
Andritz Ahlstrom); Belpress BP (available from Beltec); Krima Screw
Press (available from Cellwood); FKC (available from FKC=Fukoku
Kogyo); CHS (available from GL&V/Celleco); and Fibropress
(available from Thermo Black Clawson, Lamort).
[0041] Other types of equipment that may be included with the
de-liquefier 14 include the curved screen for example, Hydra
Screen, Hydrasieve, and Micra Screen (available from
Andritz-Ahlstrom); Bow Screen and DSM (available from Dutch State
Mines and GL&V/Celleco); and Hydrosil (Spirac) and Vertiscreen
(available from Thermo Black Clawson); the Decker; Dewatering drum
screen {e.g., (available from Corner); AKTROM (available from
Kufferath); RE (available from Saltec and Sinclair); Free Drainage
Thickener (available from Thermo Black Clawson, Lamort); Screen
Drum F type and ZTR.B (available from Voith Paper and Warburton
Holder)}; the Disc save all filter {e.g., Discfilter (available
from Hydrotech)}; the Disc thickener {e.g., AKSE (available from
Kufferath)}; the Gravity decker {e.g., Hooper (available from
Andritz-Ahlstrom and Finckh); Drainpac (available from
GL&V/Ceileco); Tamdec (available from Metso Paper/Fiber); the
Gravity screen {e.g., (available from Nash); Sweco (available from
Sweco); and the Gravity Strainer (available from Thermo Fibertek)};
the lamella plate clarifier (inclined plate clarifier, slant plate
clarifier) {e.g., Settle Plate Clarifier available from Heuser
Apparatebau)}; the Plate and frame press {e.g.,: filtomat MCFM
(available from Filtration Ltd) and Omnifilter (available from
Voith Paper)}; the Rotary pressure drum filter/washer; the Rotary
vacuum drum filter/washer; the Screw thickener {e.g., KW Washing
Screen (available from Andritz-Ahlstrom); Krima Screw De waterer
(available from Cellwood and Corner); Akusand, Akuscreen (available
from Kufferath); Sandsep, Spiropress (available from Spirac),
Hydrascreen (there is also a vertical version), and Lamort Baker
Water Extractor (available from Thermo Black Clawson, Lamort)}; the
Sidehill screen {e.g.,: Kenfil (available from Kent Filtration);
the Spraying filter {e.g.,: Spraydisc (available from
GL&V/Celleco) and White Water Filter (Sweco)}; the Tubular
filter; the Twin roll press; the PreRoll Press; WiRoll Press
(available from Metso Paper/Fiber)); and the Vibrating screen.
[0042] The waste liquid treater 42 included in the system is an
optional aspect of the invention and may be beneficial in allowing
the reuse of the liquid in the processing of the waste paper and
waste materials of the invention.
[0043] In another embodiment shown in FIG. 3, the liquid-based
fiber separator 12 may include a conveyor 44 for providing the
waste paper to the pulper 22. Also shown in FIG. 3 is that the
fiber separator 12 may include a surge tank 34 for accumulating
sufficient quantities of pulp and liquid to support pseudo
continuous processes downstream. One skilled in the art will
recognize that those types of conveyors 44 are commonly used to
feed waste paper to the pulper 22. To that end, the fiber separator
12 of the invention may include one or more conveyers 44. The
conveyer includes a steel slat type conveyor (or apron conveyor)
for baled and loose waste paper; a chain belt type conveyor for
loose waste paper, where the rubber belt is driven by a chain; and
a sliding belt type conveyor for dewired bales and loose waste
paper, where the belt (with a low friction underside) may be
supported by a steel trough. Although not shown, bale wire may be
removed automatically (dewiring) and compacted using equipment such
as: Wire Wizard (available from Advanced Dynamics, B+G
Fordertechnik, and FMW); Wirewolf (available from Lamb and
Metrans); and Wiremaster (available from Neilsen & Hiebert
Systems and Suntib).
[0044] In another embodiment, further aspects of the invention
relating to a fiber cleaning system 30 are represented in FIG. 5.
The fiber cleaning system 30 may include, for example, a screen 32,
conical cleaners 36, a washer or washers 37, and a surge tank
34.
[0045] A screen 32 may be used in the cleaning system 30 to remove
prohibitives. Common principles apply to the variety of useable
screens. In each case, the actual equipment used is that
appropriate for the fiber material and prohibitives present. A
pressure screen is one type of screen 32. Examples of such a screen
include: pressure screens (available from A. Celli, Fiedler,
Finckh; BelWave (available from GL&V); Nimega (available from
Metso Paper/Fiber); Cobra, Lehman, and ThermoTek (available from
Thenno Black Clawson, Lamort); and C Bar (Voith Paper).
[0046] Screening is commonly divided into coarse, intermediate and
fine. Coarse screening may use screen hole diameters usually
ranging between about 0.5-2.5 mm (between about 20-100 thousands),
but going up to about 10 mm at a "high consistency" feed of between
about 2 wt. % and 5 wt. %. If following a pulper extraction plate
orifice diameter of between about 3 or 6 mm, hole size may be
reduced to about 1 mm. Intermediate screening uses screen slot
widths usually ranging between about 0.25-0.65 mm (between about
10-26 thousands) at a "high consistency" feed of between about 2.5
wt. % and 5 wt. %. Fine screening uses screen slot widths usually
ranging between about 0.08-0.25 mm (between about 3.2-10 thousands)
at a "low consistency" feed of between about 1 wt. % and 3 wt. %.
One, two or three separate screenings may be used, depending on the
application. The above distinction becomes blurred when considering
the pulper extraction plate (sometimes with a screen following it)
as coarse screening and placing coarse and fine screen stages in
one pressure screen body. Examples of other usable screens include:
Ahlsorter, Hooper, MODUScreen C, H, and F (available from
Andritz-Ahlstrom); Cyberscreen, PV Screen, Selectifier and Ultra
Screen (available from Corner); C.H. Horizontal Screen, Diabolo,
and Hico Screen N (available from Finckh); Alfascreen,
CellecoScreen (both horizontal), Hi-Q, S Screen (GL&V), Key
Screen (Maule), DeltaScreen, MiniDelta Screen, TAP Screen, TAS
Screen, and TL series (available from Metso Paper/Fiber); SP Screen
series and Ultra-V (available from Thermo Black Clawson, Lamont);
and Centriscreen, EcoScreen, Minisorter, MultiSorter, Omniscreen,
Omnisorter and Spectro Screen (available from Voith Paper).
[0047] Some pressure screen bodies have two screens (e.g.:
concentric baskets), so that both slots and holes may be used
together. The stock may also be deflaked in the screen. Examples of
such screens include DeltaDouble (Metso Paper/Fiber), ADS Screen
(DS=double separation, Then no Black Clawson, Lamort), Low Pulse
Screen, LPD (Voith Paper). The MUST screen (Multistage, Metso
Paper/Fiber) can have a horizontal prescreen (typically 3 mm
diameter holes) and up to 3-wedge wire slotted screen stages
(0.08-0.45 mm).
[0048] A showering screen is a recent device intended to wash good
fiber out of the final rejects. It resembles a pressure screen
(with a basket), but also contains showers that separate good fiber
while the rotor does some deflaking. The yield of recycled pulp is
thus improved (up to 50% of rejects can be good fiber), and the
quantity for landfill reduced. Examples of its use in waste paper
systems include after the pulper and HD cleaner in the place of
multistage coarse screening and when multistage screening is
required, as a tailings screen for the final stage screen
rejects.
[0049] The four main alternative hook ups for pressure screens
include cascade, forward flow, partial cascade, and A-B
configuration. Variations exist according to the number of stages,
position in the process, equipment (e.g.: in parallel), experience,
and the like. Cascade has traditionally been used most commonly.
Accepts from the first (primary) stage continue downstream, and its
rejects are fed to the 2nd (secondary) stage. Accepts from the 2nd
stage are returned to the feed of the first (primary) stage, while
its rejects go to the 3rd (tertiary) stage. Rejects from the last
stage go to a tailings screen.
[0050] In forward flow, smaller orifices are present in the 2nd
(secondary) stage screens and 3rd (tertiary) stage screens
(relative to the first (primary) stage), and to send all their
accepts downstream (i.e., forward), rather than sending them back
to the elative to the first (primary) stage. This results in fewer
prohibitives being recirculated, but the prohibitives content of
the main stock flow may be higher.
[0051] Partial cascade is similar to forward flow, except that
accepts from the 3rd (tertiary) stage screen are screened again in
the 2nd (secondary) stage screen instead of joining the main stock
flow.
[0052] In A-B configuration, two similar screens are employed in
series for mechanical pulp screening and sometimes fine screening.
The additional unit may give greater cleanliness relative to
forward flow.
[0053] The conical cleaners 36 may include one or more
hydrocyclones. One skilled in the art will recognize that
hydrocyclone (hydroclone) is the generic name for equipment that
uses centrifugal force, and other hydrodynamic forces, produced by
pumping into a cyclone for insoluble solids separation. The cyclone
geometry provides decreasing (cross-sectional) diameter. For the
solids, this means increasing acceleration, due to the increasing G
force, i.e., acceleration measured relative to the acceleration of
free fall due to gravity, 9.81 m/s.sup.2, and increasing
Prohibitive/fiber separation efficiency. Banks (e.g., rows) of the
numerous individual cleaners may be combined in a variety of
orientations (a circle, rows, etc.) so as to share common feed and
discharge chambers. Examples of such a variety of orientations
include: Spirelpak (available from Thermo Black Clawson, Lamort)
and Tripac 90 (available from GL&V/Celleco).
[0054] The conical cleaners 36 may include one or more of a forward
flow (conventional) cleaner; a high density cleaner, a reverse
cleaner, a through flow cleaner, core bleed cleaner, an
asymmetrical cleaner and a rotating body cleaner. A conventional
centrifugal cleaner (CC, centricleaner, forward flow cleaner, free
vortex cleaner) is approximately the shape of a narrow cyclone
(i.e., an inverted cone), with the stock entering at a tangent in
the top. A whirlpool like vortex is formed, so that high density
prohibitives move to the bottom of the cone from where they are
rejected. The accepted stock goes to the top of the cone from where
it passes upstream. Examples of forward flow (conventional)
cleaners include: Ahlcleaner RB series, Centri Cleaner, and TC
series (available from Andritz-Ahlstrom, Corner and Fiedler); Albia
T, Cleanpac 270 to 1500 series, Elast 0 Cone, Posiflow and TW
series (available from GL&V); CT series, Hydraclone, ELP series
and Ultra Clone (available from Thermo Black Clawson, Lamort); and
Cyclean, and KS series (available from Voith Paper and Wilbanks).
Up to about 5 stages of cleaners may be used, depending on the
cleanliness required.
[0055] A high density cleaner (HD cleaner) is a urge diameter
forward flow cleaner operating between the ranges of about 2% and
6% consistency. It is located close to the pulper when using lower
grade waste paper furnishes and removes high density prohibitives.
An elutriation section helps to separate fiber from rejects. The
latter are removed from the rejects chamber either manually (via
the door) or automatically (by 2 timed valves). Examples of high
density cleaner {HD cleaner) include: (that available from A.
Celli); Ahlcleaner RB 300HD (available from Andritz-Ahlstrom);
Cleantrap, Grubbens High Density Cleaner (available from Cellwood),
(Corner); Albia TFRB, Combitrap (available from GL&V); HC
Cleaner (available from Metso Paper/Fiber); HD Cyclone, Liquid
Cyclone, Low Profile Cyclone and Ruffclone (available from Thermo
Black Clawson, Lamort, Aikawa); DIC, D2C, and High-Consistency
Purifier S series and T series (available from Voith Paper).
[0056] In a reverse cleaner, the normal accepts and rejects exit
points are reversed. Good low-density prohibitives removal may be
achieved. About 50% of the flow (and proportionally more of the
fiber) may be rejected. The accepts flow may be thickened by a
factor of up to about 2.5. Examples of reverse cleaners include:
Cleanpac 2708, Cleanpac RT (reverse, thickening), Tripac 90 Reverse
(available from GL&V/Celleco); Contra-Clone, CT series, and
Xtreme, (available from Thermo Black Clawson, Lamort); and KS
series (available from Voith Paper).
[0057] In a through flow cleaner (flow through, parallel flow),
both the rejects and accepts come out at the same end. It removes
low density prohibitives together with air. Rejects are about 10%
of the feed flow. Examples of through flow cleaners (flow through,
parallel flow) include: Cleanpac 250 LWR and UniFlow (available
from GL&V); XX-Clone (available from Thermo Black Clawson); and
Coreclean (available from Voith Paper).
[0058] The core bleed cleaner has the configuration of a forward
flow cleaner, but with the addition of a central bleed for low
density prohibitives (plus deaeration) from the accepts stream.
Each rejects stream equals about 10% of the feed flow. Examples of
core bleed cleaners include: Ahlcleaner SC 133 (available from
Andritz-Ahlstrom); Albia TDLR, Cleanpac 350 Combi, and Cleanpac 700
LD (available from GL&V); and KS/E series (available from Voith
Paper).
[0059] The asymmetrical cleaner is essentially a forward flow
cleaner, but with one straight side and, the other side converging
on it. This departure from symmetry about a central axis provides,
among its benefits, the ability to manipulate (and remove)
particles according to their position within the cleaner strata
(e.g., levels). The asymmetrical cleaner takes two different forms:
those resembling the Cleanpac 270 SR (Step Release having steps in
the converging side plus a constricted cone end removed available
from GL&V/Celleco) and those resembling the Cleanpac 270 HyS
(having increases in the feed and accepts pressure available from
GL&V/Celleco).
[0060] The rotating body cleaner differs from the others in that a
horizontal cylinder (e.g., 500 mm diameter) rotates at 1,300-1,500
rev/min, thus exerting a greater centrifugal force of about 700 G
over a longer retention time, to give good low-density prohibitive
removal efficiency. An example of a rotating body cleaner includes
the Gyroclean (available from Thermo Black Clawson, Lamort).
Gyrocleans may be efficient stickies separators.
[0061] An elutriation section may be added to the last stage of a
conical cleaner 36 to reduce the rejects' fiber content and liquid
consumption. This may be achieved by injecting liquid, which pushes
good fiber back into the system for subsequent separation. The
elutriation section may include valves to periodically discharge
the rejects. Examples of elutriation sections include: Albia WFRC
(water and fiber recovery control), FRB, RCC, and Fibermizer FMZ
(available from GL&V) and Rejectomat (available from Voith
Paper).
[0062] Another embodiment of the invention is represented by
reference to FIG. 6 which shows the fiber separator 12, fiber
cleaning system 30, and de-liquefier 14 combined in a manner that
is beneficial for production of recycled pulp according to the
invention.
[0063] In other embodiments of the invention, the apparatus can
optionally further comprise a means for de-inking the waste paper
and/or recycled pulp. De-inking is the process of removing ink and
other contaminants from waste paper De-inking means are known in
the art and described, for example, in U.S. Pat. Nos. 6,576,083,
6,544,383, 6,426,200, 6,217,706, and the like. In one embodiment,
the de-inking means can be flotation de-inking. In another
embodiment, the de-inking means can be a combined flotation/wash
de-inking process. In another embodiment, the de-inking means can
be an enzymatic de-inking means.
[0064] In other embodiments of the invention, the apparatus of the
invention can optionally further comprise a means for bleaching the
waste paper and/or recycled pulp. Bleaching means are well known in
the art and described, for example, in U.S. Pat. Nos. 6,569,284,
6,533,896, 5,989,388, and the like. Bleaching is generally
accomplished with ozone, hydrogen peroxide and/or chlorine.
[0065] In operation, the starting material for the methods and
apparatus of the invention is one grade of waste paper or is a
mixture/combination of two, three, four, five, six, seven, or more
grades of waste paper. The waste paper, which optionally contains
prohibitives, is provided to an apparatus 10 for treating fibrous
material as depicted in the Figures and described herein. Any of
the grades of waste paper may be provided to the fiber separator 12
to break the waste paper down to a recycled pulp. The recycled pulp
is then optionally transferred to the de-liquefier 14 to remove
liquid. The de-liquefied material may be transferred to containers
for shipping to a different location, e.g., to a paper mill.
[0066] In one embodiment of the invention shown in FIG. 6, the
process of the apparatus 10 includes a fiber separator 12, a fiber
cleaning system 30 and de-liquefier 14. In the liquid-based fiber
separator 12, the waste paper is run to the pulper 22 on conveyor
44 and mixed with water to between about 7 wt. % and 15 wt. %
consistency and pulped for up to 45 minutes. The pulp is then
diluted with water, filtered and moved to chest 34. The fiber is
then pumped through the cleaning system 30 and on to chest 34. The
resulting pulp is then put through the de-liquefier 14.
[0067] The waste paper and/or waste material (e.g., waste paper and
prohibitives) that is used in the methods, systems and apparatus of
the invention can be obtained from any source known in the art. In
one embodiment, the waste paper and/or waste material is obtained
from a material recovery facility (MRF). A MRF generally serves as
a drop-off and gross-sorting (and limited processing) point for
recycled materials. Recyclable materials generally enter a MRF
either in a single stream or dual stream. A single stream consists
of a mixture of glass, plastics, and/or metals, and the waste paper
described herein. A dual stream MRF consists of a commingled
container stream and a separate waste paper and/or waste material
stream. While traditional MRFs typically utilize a dual stream
configuration, the desire to reduce labor and other operational
costs has been an impetus behind the trend toward single stream
MRFs. In one embodiment of the invention, the apparatus used to
produce the recycled pulp of the invention can be at the same
location (e.g., in the same building or adjacent building) as the
MRF in order to eliminate the costs associated with transporting
the waste paper/waste material to the facility to be converted into
recycled pulp. The MRF provides an excellent source of waste
material/waste paper for the apparatus, systems and methods of the
invention.
[0068] Various modifications of the invention, in addition to those
described herein, will be apparent to one skilled in the art from
the foregoing description. Such modifications are intended to fall
within the scope of the appended claims.
* * * * *