Abstract:
A contaminate separation apparatus for use in separating contaminant materials from cellulose and/or paper fibres in a paper recycling process includes a reservoir for receiving a waste paper slurry therein. The reservoir is provided with an inlet opening for the input of the slurry, one or more fibre discharge outlets or passages, and at least one waste outlet positioned vertically above the fibre discharge outlet opening. An agitator provided in a lower portion of the reservoir generates differential flow currents within the reservoir, to selectively divert plastics, waxes, adhesives and/or other sticky waste materials outwardly towards the waste outlet, while providing a flow of suspended paper and/or cellulose fibres to one or more of the fibre discharge outlets.

Description:
SCOPE OF THE INVENTION 
       [0001]    The present invention relates to an apparatus for use in a paper recycling process to separate waste and contaminant materials from paper and cellulose fibres, and a method for using same. 
       BACKGROUND OF THE INVENTION 
       [0002]    The diversion of paper, cardboard and other cellulose-based products from municipal and commercial waste for use in the manufacture of recycled paper has been widely adopted as a method of reducing the volume of garbage and waste material to be landfilled. Approximately 60 to 70% of conventional paper waste such as newspapers, office letterhead, stationery, box board and/or cardboard is of a sufficiently high quality grade to enable its direct recycling for use in the remanufacturing of recycled paper products. 
         [0003]    A significant portion of diverted paper waste, however, contains contaminants which hinders use in recycled paper manufacturing processes. For example, frequently paper waste includes contaminant materials such as gum labels, soluble and insoluble adhesives, hot melt glues, adhesive bindings, wax coatings, window envelopes and/or laminated papers and residues. The presence of such contaminant materials has heretofore resulted in a significant portion of diverted paper waste being deemed unsuitable for recycling applications, necessitating its incineration and/or landfill. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention seeks to provide an apparatus which may be economically manufactured and used to separate contaminants such as plastics, waxes, glues, adhesives and other such sticky residues from recycled waste paper or cellulose fibres for further use in paper recycling processes. 
         [0005]    Another object of the invention is to provide a system for recycling paper waste which provides improved efficiencies in the separation of paper and/or cellulose fibres from plastics, adhesive residues and other contaminant materials present in the diverted waste material. 
         [0006]    A further object of the invention is to provide an apparatus used for separating contaminant materials from cellulose fibres in a waste stream or slurry and which may be economically operated and/or installed in conventional recycling and/or classification systems. 
         [0007]    Another object of the invention is to provide a contaminant separation apparatus which is operable to separate contaminant material from cellulose fibres from a recycled paper slurry supplied to the apparatus as a substantially continuous flow. 
         [0008]    To at least partially achieve some of the foregoing objects and/or overcome disadvantages of the prior art, the present invention provides for a contaminate separation apparatus for use in separating contaminant materials from cellulose and/or paper fibres in a paper recycling process. The apparatus includes a reservoir for receiving liquefied slurry of waste, and more preferably diverted paper waste which is to be recycled therein. The reservoir is provided with an inlet opening for receiving a volume of the slurry, one or more fibre discharge outlets or passages, and at least one waste outlet positioned vertically above a fibre discharge passage opening. 
         [0009]    An agitator is provided in a lower portion of the reservoir for use in generating differential flow currents within the reservoir to selectively divert plastics, waxes, adhesives and/or other waste materials outwardly towards the waste outlet, while providing a flow of suspended paper and/or cellulose fibres towards one or more of the fibre discharge outlets. Suitable agitators could, for example, include mechanical agitators, as well as fluid outlet nozzles of different diameters and/or configurations adapted to introduce different water, fluid and/or waste stream flows into the reservoir. In a most simplified construction, the agitator is provided as a gas outlet or nozzle which is selectively operable to supply a gas flow, such as air to a lower region, and most preferably a bottom central region of the reservoir. The applicant has appreciated that the introduction of a gas flow into the reservoir advantageously results in the adhesive, waxes, plastics and other lower density contaminants being entrained with the gas bubbles to differentially move towards the upper regions of the reservoir, while the comparatively denser longer paper fibres tend to settle towards the reservoir sides. 
         [0010]    Most preferably, one or more fibre discharge passages are provided which extend from an inlet opening provided in fluid communication with the reservoir interior. The inlet opening is spaced remote from the agitator and intermediate the contaminant waste outlet and the inlet opening through which the waste paper slurry is introduced into the reservoir. Preferably one or more baffle members are provided which extend partway across the interior reservoir. The baffle members are positioned at least in part above one or more of the inlet openings of the discharge passages to assist in the diversion of paper and/or cellulose fibres into the filter discharge passages. Baffle members of various configurations may be used, including horizontal, planar and/or tubular or curved baffles. In one preferred embodiment, a baffle is provided which extends about the interior periphery of the reservoir and which has a substantially planar construction extending angularly downwardly immediately above the inlet openings. 
         [0011]    In use, a fluidized waste stream or slurry is supplied into the reservoir, and most preferably into the lower region of the reservoir, in either a batch process or continuously. As the waste slurry is introduced into the reservoir, a gas such as nitrogen, oxygen or air is simultaneously introduced into the bottom of the reservoir via the gas outlet nozzle to generate an upward flow. The gas is provided with a preferred flow rate between about 0.1 and 1 cubic meters per minute, depending on the volume of the reservoir and the flow rate of the slurry therein. As the gas is introduced, the lower density contaminant materials tend to move with the gas bubbles upwardly towards the upper regions of the reservoir. The liquid along the top of the reservoir may thus be diverted together with the contaminant materials entrained therein into the waste outlet for disposal. Simultaneously, the paper and cellulose fibres in the slurry tend to settle towards the bottom of the reservoir, moving toward the lower reservoir sidewalls where they are diverted via the baffles into the fibre discharge passages. 
         [0012]    Accordingly, in one aspect the present invention resides in an apparatus for separating contaminant material from paper or cellulose fibres in a waste stream slurry, the apparatus including, 
         [0013]    a reservoir for receiving a volume of said slurry therein, said reservoir including a sidewall extending from a lower edge portion to an upper edge portion, 
         [0014]    a slurry infeed opening proving fluid communication between a slurry supply and a lower region of said reservoir, 
         [0015]    a contaminate waste outlet spaced toward said upper edge portion and in fluid communication with said reservoir, 
         [0016]    at least one baffle member disposed in said reservoir and positioned intermediate said infeed opening and said waste outlet, 
         [0017]    at least one fibre discharge passage providing fluid communication between an inlet opening proximate to an underside of a portion of a selected said baffle member and a discharge outlet spaced vertically above said inlet opening, and 
         [0018]    a gas nozzle selectively operable to supply a gas flow to said lower region of said reservoir. 
         [0019]    In another aspect, the present invention resides in use of a separation apparatus for separating contaminants from cellulose fibres in a slurry, the apparatus comprising 
         [0020]    a reservoir for receiving a volume of said slurry therein, said reservoir including a sidewall extending from a lower edge portion to an upper edge portion, 
         [0021]    a slurry infeed opening proving fluid communication between a slurry supply and a lower region of said reservoir, 
         [0022]    a waste outlet spaced toward said upper edge portion and in fluid communication with said reservoir, 
         [0023]    at least one baffle member disposed in said reservoir and positioned intermediate said infeed opening and said waste outlet, 
         [0024]    at least one fibre discharge passage providing fluid communication between a passage inlet opening proximate to an underside of a portion of a selected said baffle member and a discharge outlet spaced vertically above said inlet opening, and 
         [0025]    a gas nozzle selectively operable to supply a gas flow to said lower region of said reservoir, 
         [0026]    and wherein said waste stream slurry comprises at least about 90% water and is fed into said reservoir through said infeed opening at a rate selected at between about 0.2 and 5 cubic meters per minute. 
         [0027]    In a further aspect, the present invention resides in an apparatus for separating plastic and adhesive materials from paper fibres in a recycled paper waste slurry, the apparatus including, 
         [0028]    a reservoir for receiving said slurry therein, said reservoir including a generally cylindrical sidewall extending along an axis from a lower edge portion to an upper edge portion, 
         [0029]    an infeed opening through said sidewall and providing fluid communication between a slurry supply and a lower region of said reservoir, 
         [0030]    a contaminant waste outlet spaced toward said upper edge portion and providing fluid communication between said reservoir and a waste discharge, 
         [0031]    a baffle member disposed in said reservoir and projecting radially about said sidewall part way towards said axis, said baffle member being positioned intermediate said infeed opening and said waste outlet, 
         [0032]    a plurality of fibre discharge passages, said discharge passages being radially spaced about said axis and providing fluid communication between a respective passage inlet opening proximate to an underside of said baffle member and a discharge channel spaced vertically a distance above the passage inlet opening, 
         [0033]    a gas nozzle selectively operable to supply a gas flow to said lower region of said reservoir. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]    Reference may now be had to the following detailed description taken together with the accompanying drawings in which: 
           [0035]      FIG. 1  illustrates schematically a system for the removal of contaminate materials from paper waste in a paper recycling process, in accordance with a preferred embodiment of the invention; 
           [0036]      FIG. 2  shows a perspective view of a contaminant separation apparatus used to separate contaminant materials from paper fibres in operation of the system of  FIG. 1 ; 
           [0037]      FIG. 3  shows a perspective top view of the apparatus of  FIG. 2 ; 
           [0038]      FIG. 4  illustrates a perspective front view of the apparatus of  FIG. 2 ; and 
           [0039]      FIG. 5  illustrates schematically an enlarged cross-sectional view of the apparatus of  FIG. 2  taken along lines  5 - 5  in operation. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0040]      FIG. 1  illustrates schematically a system  8  used in the removal of contaminant material such as plastics, adhesives, wax residues, hot melt glues and binding remnants from paper fibres in waste paper, which has been diverted from municipal and/or commercial waste streams for recycling as remanufactured paper products. In the embodiment shown, the system  8  includes a homogenizing or mixing tank  10 , a contaminant separation apparatus  20 , a primary fibre washing/thickening station  70 , a secondary fibre washing/thickening station  80 , and a residual ash removal station  90 . Suitable washing/thickening stations  70 , 80  and ash removal station  90  include, for example, conventional rotating screening apparatus similar to the type which, for example, are disclosed in issued Canadian Patent No. 2,182,833 to Langner. The liquid material and suspended solids are fed into the interior of a rotating screening cylinder to effect filtration and separation of particulate material from the water filtrate. 
         [0041]    As will be described, most preferably, the system  8  operates as a substantially continuous flow process. It is to be appreciated, however, that in a less preferred mode of operation, the system  8  could be operated either partially or in entirety as a batch operation. 
         [0042]    Initially, diverted paper material is shredded and fed into a mixing tank  10  where it is mechanically admixed with water to form a homogenous slurry  12 . Most preferably, the slurry  12  is formed having a water content selected at between about 90 and 98%, and more preferably between about 96 and 97%. 
         [0043]    Following its homogenization, the slurry  12  is pumped from the mixing tank  10  into the contaminant separation apparatus  20  which is used to classify the slurry  12  into separately fluidized streams, one stream ( 12   a ) containing primarily separate contaminate material, and the other stream ( 12   b ) containing primarily paper fibres ( FIG. 5 ). The fluid stream  12   b  containing the purified paper fibre/water mixture is then fed initially into the primary fibre washing/thickening station  70 . The station  70  is used to initially separate larger paper fibres from the infed water/fibre stream  12   b  for use in the formation of remanufactured paper and/or other recycled paper products. In this regard, the station  70  preferably incorporates a screening drum selected for the primary diversion of larger paper fibres having a length selected greater than 750 microns. These collected primary fibres may then be sold to a mill for use in recycled paper manufacture. 
         [0044]    The resulting filtrate  12   b ′ from station  70  is then fed by way of fluid pump (not shown) to the secondary washing/thickening station  80 . Station  80  is used to extract smaller paper fibres from the filtrate  12   b ′ which have a fibre length greater than 150 microns for use as boiler feed, or in manufacturing and/or recycling. 
         [0045]    Final processing of the filtrate  12   b ″ from the secondary washing/thickening station  80  occurs in the ash removal station  90 . In station  90 , ash is removed and cleaned for use as fertilizer. Any remaining contaminants in the station  90  are collected for disposal. 
         [0046]      FIGS. 2 to 5  illustrate best the contaminant separation apparatus  20  used in the system  8  in accordance with a preferred embodiment of the invention. The apparatus  20  includes reservoir tank  24  having a generally cylindrical sidewall  26  and which is sealingly closed at its lowermost end by bottom panel  28  ( FIG. 3 ). The sidewall  26  extends radially about a central axis A 1 -A 1  ( FIG. 4 ) to provide the tank  24  with a radial diameter D selected at between about 0.5 and 5 meters, preferably about 1 and 3 meters, and most preferably about 1.5 meters. The sidewall  26  extends in the axial direction from the bottom panel  28  to an uppermost lip  30 , a vertical height of between about 0.5 to 5 meters, preferably 1 to 3 meters, and most preferably about 2 meters. 
         [0047]      FIGS. 3 and 4  illustrate best the apparatus  20  as including a fluid infeed pipe  32  which extends through the sidewall  26  immediately adjacent the panel  28 . The infeed pipe  32  provides fluid communication between the mixing tank  10  and interior of the reservoir tank  24 . The infeed pipe  32  is sized to allow the waste stream slurry  12  to be fed into the apparatus  20  in a substantially continuous flow manner. 
         [0048]    An air supply tube  34  ( FIG. 4 ) furthermore is provided through the sidewall  26  adjacent the bottom panel  28 . As shown best in  FIG. 5 , the air supply tube  34  provides gaseous communication between a pressurized air source  36  and a bubble diffuser  38  which is provided immediately adjacent the bottom panel  28  aligned with the reservoir axis A-A 1 . The pressurized air source  36  is selectively operable to supply pressure in air flow to the interior of the tank  24  via the bubble diffuser  38  at a gas flow rate selected at between about 0.2 and 5 cubic meters per minute, preferably about 0.3 to 1 cubic meters per minute, and most preferably about 0.75 meters per minute, depending upon the rate of inflow of the slurry  12  into the bottom of the reservoir tank  24 . 
         [0049]      FIGS. 3 and 4  furthermore show best the reservoir tank  24  as including a contaminate waste discharge port  40  formed through the sidewall  26  spaced immediately below the upper lip  30 . The discharge port  40  is provided in fluid communication with a waste discharge pipe  42  ( FIG. 5 ) which is used to convey a waste fluid stream  12   a  containing plastics, adhesive residues and other contaminate material separated from the slurry  12  for disposal by landfill and/or incineration. 
         [0050]      FIGS. 3 and 5  show best an annular flange member  44  as being disposed about the interior of the sidewall  26 . The annular flange member  44  projects from the sidewall  26  radially inwardly towards the axis A-A 1 , and downwardly at an angle selected at between about 30 and 60° and more preferably about 45° relative to the sidewall  26 . The flange member  44  has a length selected at between about 4 and 40 cm, and more preferably about 15 to 20 cm. 
         [0051]    As shown best in  FIGS. 2 and 5 , a series of fibre discharge passages  46   a , 46   b , 46   c , 46   d , 46   e  are provided at radially spaced locations about the sidewall  26 . Each discharge passage  46  extends respectively from a passage inlet opening  48  vertically upwardly along the outside of the sidewall  26 , opening into the bottom of a launder ring  50 . The inlet openings  48  are formed through the sidewall  26  approximately one-half to two-thirds of the distance from the bottom panel  28  to the lip  30 . Most preferably, the openings  48  are each located immediately adjacent to an underside of the flange member  44 , with each discharge passage  46  extending generally vertically therefrom with a length of at least about 10 cm, and most preferably between about 30 and 100 cm. 
         [0052]    The launder ring  50  is preferably provided as a U-shaped channel which extends radially about the uppermost lip  30  of the sidewall  26 . The lower extent of the launder ring  50  is provided vertically adjacent to the waste discharge port  42 . The laundering  50  opens along a side of the reservoir  24  to a discharge outlet  52  for the paper fibre stream  12   b . The fibre discharge outlet  52  is most preferably radially opposed to contaminate discharge port  40 . Although not essential, the reservoir tank  24  may be mounted on leg supports  54  so that the tank axis A-A 1  is inclined an angle between about 2 and 7.5° relative to the vertical towards the discharge outlet  52 , with the result that the lower extent of the discharge outlet  52  locates between about 0.2 and 10 cm, preferably 0.2 cm and 0.4 cm below the lower extent of the waste discharge port  40 . Piping  56  ( FIG. 5 ) provides fluid communication between the discharge outlet  52  and the primary washing/thickening station  70  to convey the fluid stream  12   b  containing paper fibres separated from the slurry  12  for further processing. 
         [0053]    Optionally, a cleanout drain  60  may be provided in the bottom panel  28 . The cleanout drain  60  allows the reservoir tank  24  to be drained for periodic cleaning and/or maintenance. 
         [0054]    In use of the apparatus  20 , the homogenized waste slurry  12  having a water content of between 95 and 98%, and most preferably about 97% is pumped or more preferably fed under gravity from the mixing tank  10  to the reservoir tank  24 . The slurry  12  is fed into the reservoir tank  24  through the infeed pipe  32  at a preferred continuous flow rate of about 2 cubic meters per minute. Simultaneously, as the waste slurry  12  is fed into the reservoir tank  24 , the pressurized air source  36  is operated. The air source  36  provides a continuous stream of air into the bottom of the reservoir  24  via bubble diffuser  38  with a flow volume of between about 0.1 and 1 cubic meters per minute. The introduced air bubbles (shown as  100  in  FIG. 5 ) rise vertically through the slurry  12  generally along the axis A 1 -A 1  in the direction of arrow  110 . As the gas bubbles  100  rise in the reservoir tank  24 , contaminant material in the slurry  12 , such as plastics, waxes and other glues and adhesive residues, are entrained with the rising bubbles  100 . As a result, the contaminate material travels in an upward axially centered flow path, so as to move upwardly past the flange member  44 . Concurrently, heavier paper fibres tend not to rise with the bubbles  100 , moving towards the lower edges of the sidewall  26 . The continuous flow of additional waste slurry  12  into the bottom of the reservoir tank  24 , results in the contaminate material moving upwardly and then flowing as part of a waste flow stream  12   a , outwardly from the apparatus  20  via the waste discharge port  40  and pipe  42 . 
         [0055]    Simultaneously, paper fibres are left behind as they tend not to be entrained with air bubbles  100 . The result is that the paper fibres are concentrated and collect along the periphery of the sidewall  26 . The continued inward movement of waste slurry  12  into the bottom portion of the reservoir tank  24  causes the flow of paper fibres to move upwardly against the underside of the flange member  44 . Continued fluid flow results in a fluid stream  12   b  containing paper fibres with reglued concentrations of contaminant materials to move into the inlet openings  48  of the fibre discharge passages  46   a , 46   b , 46   c , 46   d , 46   e  and upwardly therealong into the launder ring  50 . The fluid flow  12   b  containing paper fibres thus travels along the discharge passage  46  into the launder ring  50 , flowing outwardly therefrom into the piping  56  via the discharge outlet  52 . 
         [0056]    The applicant has appreciated that the present apparatus  20  permits the removal of plastics, adhesives and other contaminants from recycled paper waste without requiring expensive filtration, or the use of mechanical screening and/or pumps. Accordingly, the apparatus  20  may be economically operated and is ideally suited for large scale paper processing and recycling operations. 
         [0057]    Although  FIGS. 2 to 5  illustrate the reservoir tank  24  as having an annular flange member  44 , the invention is not so limited. It is to be appreciated that suitable baffle members could also be provided, or baffles omitted in their entirety. Similarly, it is envisioned that fibre discharge passages  46  having differing shapes and/or configurations alone, or in combination with flange members of different profiles could also be used, without departing from the spirit and scope of the invention. 
         [0058]    Although the preferred embodiment describes and illustrates the reservoir  24  as having a generally cylindrical sidewall construction, the invention is not so limited. It is to be appreciated that the present apparatus could equally be provided with a number of different sidewall  26  configurations including, without restriction, sidewalls having a generally square, oval or spherical cross-sectional profile. 
         [0059]    Although the detailed description describes the contaminant separation apparatus  20  as used in a paper recycling process for the separation of waxes, glues plastics and adhesive residues, and the like from paper fibres, the invention is not so limited. It is to be appreciated that the apparatus  20  may be used in the separation of contaminants or other undesired materials in a variety of manufacturing, waste treatment and/or classification processes. By way of non-limiting example, such applications could include the treatment of pulp waste, other chemical industries or purification systems, food-manufacturing applications, as well as other liquid waste treatment processes. 
         [0060]    Although the detailed description describes and illustrates various preferred aspects, the invention is not so limited. Many modifications and variations will now occur to persons skilled in the art. For a definition of the invention, reference may be had to the appended claims.