

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

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.

InFIG. 1, anapparatus10 for converting waste material into recycled pulp is shown. Theapparatus10 comprises at least onefiber separator12 and, optionally, at least onewaste liquid treater42 in communication with thefiber separator12. Thefiber separator12 is preferably a liquid-based fiber separator, such as an aqueous based fiber separator. Theapparatus10 can optionally comprise at least onejunk trap15 and/or at least oneragger16 for removing prohibitives.

InFIG. 2, theapparatus10 comprises at least onefiber separator12, at least onede-liquefier14, and, optionally, at least onewaste liquid treater42 in communication with thefiber separator12 and/or the de-liquefier14. The de-liquefier14 is located downstream from thefiber separator12 and the de-liquefier14 is for removing liquid from the recycled pulp. Thefiber separator12 may be a liquid-based fiber separator, such as an aqueous based fiber separator. Theapparatus10 can optionally comprise at least one junk trap (not shown) and/or at least one ragger (not shown) for removing prohibitives.

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.

The removal of large prohibitives from waste paper may be achieved by subsystems around thefiber separator12, such as ajunk trap15. 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™ is an example of such a junk trap.

Aragger16 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 thefiber separator12 as an endless ragger rope by the capstan-like ragger16. 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 thefiber separator12 without emptying it. An example of equipment useful for such operations includes the Ragger tail grabber (available from Neilsen & Hiebert Systems).

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).

In other embodiments of the invention, thefiber separator12 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).

In other embodiments, thefiber separator12 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).

As shown inFIG. 4, the de-liquefier14 may include any of the many types of equipment used for thickening, washing, and/or separation. For example, the de-liquefier14 may include athickener25 for increasing the solids content of the recycled pulp that comes out of the liquid-based fiber separator1.

The liquid removed by the de-liquefier14 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).

The de-liquefier14 may include ascrew press40 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).

Other types of equipment that may be included with the de-liquefier14 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.

Thewaste liquid treater42 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.

In another embodiment shown inFIG. 3, the liquid-basedfiber separator12 may include aconveyor44 for providing the waste paper to thepulper22. Also shown inFIG. 3 is that thefiber separator12 may include asurge tank34 for accumulating sufficient quantities of pulp and liquid to support pseudo continuous processes downstream. One skilled in the art will recognize that those types ofconveyors44 are commonly used to feed waste paper to thepulper22. To that end, thefiber separator12 of the invention may include one ormore conveyers44. 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).

In another embodiment, further aspects of the invention relating to afiber cleaning system30 are represented inFIG. 5. Thefiber cleaning system30 may include, for example, ascreen32,conical cleaners36, a washer orwashers37, and asurge tank34.

Ascreen32 may be used in thecleaning system30 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 ofscreen32. 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).

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).

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).

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.

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.

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.

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.

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.

Theconical cleaners36 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/s², 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).

Theconical cleaners36 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.

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).

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).

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).

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).

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).

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.

An elutriation section may be added to the last stage of aconical cleaner36 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).

Another embodiment of the invention is represented by reference toFIG. 6 which shows thefiber separator12,fiber cleaning system30, and de-liquefier14 combined in a manner that is beneficial for production of recycled pulp according to the invention.

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.

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.

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 anapparatus10 for treating fibrous material as depicted in the Figures and described herein. Any of the grades of waste paper may be provided to thefiber separator12 to break the waste paper down to a recycled pulp. The recycled pulp is then optionally transferred to the de-liquefier14 to remove liquid. The de-liquefied material may be transferred to containers for shipping to a different location, e.g., to a paper mill.

In one embodiment of the invention shown inFIG. 6, the process of theapparatus10 includes afiber separator12, afiber cleaning system30 andde-liquefier14. In the liquid-basedfiber separator12, the waste paper is run to thepulper22 onconveyor44 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 tochest34. The fiber is then pumped through thecleaning system30 and on tochest34. The resulting pulp is then put through the de-liquefier14.

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.

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.