SEPARATION OF CELLULOSIC AND NON-CELLULOSIC FRACTIONS FROM PAPER PRODUCTS

Abstract: A process (1) for the separation of cellulosic fibres from non-cellulosic fractions in paper product is disclosed. The paper product comprises cellulosic fibres and at least one of thermoplastic polymer and metallic foil. The process (1) comprises vigorously admixing paper product in aqueous solution (3) in a vessel (2), the paper product being in a comminuted form and the vessel (2) being such that the solution (3) has a surface (11) within the vessel (2). The admixing is such that it is effective for at least partial separation of cellulosic fibres from thermoplastic polymer and metallic foil and to form a suspension of cellulosic fibres so separated in the aqueous solution (3). A fraction (13) comprised of thermoplastic polymer and/or metallic foil is separated from the surface (11) of the aqueous solution (3) in the vessel (2). The separation is carried out by using a bucket conveyer (6) extending below the surface (11) of the aqueous solution (3) and discharging the fraction (13) outside of said vessel (2). The process is useful for separating coated paperboard into its components, e.g. for recycling of beverage containers.

Description: TITLE SEPARATION OF CELLULOSIC AND NON-CELLULOSIC FRACTIONS FROM PAPER PRODUCTS FIELD OF THE INVENTION The present invention relates to a process for the separation of cellulosic fibres from non-cellulosic fractions in paper products. In particular, the present invention relates to the separation of cellulosic fibres from thermoplastic polymer film and/or metallic foil in paper products having combinations of such components. In particular aspects, the invention relates to the recycling of absorbent sanitary paper products, coated paperboard and the like. As used herein, absorbent sanitary paper products include disposable diapers, incontinence products, feminine hygiene products, bed pads and other related absorbent and adsorbent products. Coated paperboard includes beverage and juice boxes and other laminates of cellulosic fibres and thermoplastic polymers, some of which also contain metallic foil. BACKGROUND OF THE INVENTION Absorbent sanitary paper products typically consist of (i) a non-woven sheet formed from a liquid permeable material, for example a liquid permeable membrane formed from polypropylene, polyethylene, or woven products formed from cotton or rayon, (ii) a liquid impermeable back sheet formed from for example polyethylene, polypropylene, starch based degradable plastic films, woven cloth or rubber, and (iii) an adsorbent or absorbent core of air laid wood pulp fluff, commonly referred to as air felt, and/or synthetic pulp including polypropylene or polyethylene filaments that may be bonded or unbonded, hemp or other adsorbent fibrous material. The core is typically wrapped or encased in a creped envelope of wet strength tissue paper or a material with similar characteristics. The wrapping on the core may or may not be breathable, biodegradable, odour degradable or degradable or dissolvable by other means. The core usually also contains a super absorbent polymer (SAP) material, which is typically a polyacrylate, polyacrylamide, crosslinked starch or other hydrophillic component, which may be synthetic, and may be in granular, fibrous or laminate form, possessing the ability to bond with water, urine or other body fluids or retain them without substantial release or discharge from the absorbent portion. Diapers and incontinence products typically utilize pressure sensitive adhesives for refastenable tape tabs or similar closure mechanisms. Feminine hygiene pads and incontinence products often use pressure sensitive adhesives for glue lines to attach the pad or liner to the user's undergarments. Diaper and incontinence products typically utilize elastic, polyurethane, puckering and welding or adhesives to create close fitting cuffs around the leg and waist openings to provide a more leakproof fit. There is an increasing volume of coated paperboard in which one or both sides or faces of the paperboard have been coated with thermoplastic polymer film or thermoplastic polymer film and e.g. aluminum foil. The resultant coated paperboard is used, in particular, in the beverage industry, for example, in the packaging of fruit juices, other liquid drinks, e.g. flavoured and sweetened aqueous drinks of various kinds, milk and a variety of other beverages. The coated paperboard used in this industry tends to be coated on both sides with an outer layer of a heat sealable thermoplastic polymer, for example, polyethylene or related polyolefin. Such coatings serve the dual purpose of providing a barrier to retain the liquid within the beverage container as well as a means by which the beverage container may be shaped and formed and retained in its formed shape e.g. using heat sealing techniques. The coated paperboard may have a layer of aluminum or other metallic foil, usually as an intermediate layer between the thermoplastic polymer and cellulosic fibre layers. Absorbent sanitary paper products and coated paperboard products, and other related types of products, are normally disposed of along with garbage generated by households, institutions, hotels and the like, by incineration or in landfill disposal sites. Incineration tends to result in air or other pollution being generated. Landfill disposal results in an accumulation of such products. Society is increasingly demanding alternate methods of disposing of such products, and especially methods leading to recycling of components. A process for the treatment of absorbent sanitary paper products in order to separate cellulosic fibres from other materials e.g. plastic layers, is disclosed in published PCT application WO 92/07995 of M.E. Conway et al, published May 14, 1992. A process for the treatment of coated paperboard is disclosed in the patent application of M.E. Conway and S.A. Martin filed concurrently herewith. SUMMARY OF THE INVENTION An improvement has now been found in processes for the treatment of absorbent sanitary paper products and plastic coated paperboard, especially processes intended for recycling of cellulosic fibres and other components, in which thermoplastic polymer and/or metallic foil is separated from an aqueous solution containing such products in a comminuted form. Accordingly, one aspect of the invention provides a process for the separation of cellulosic fibres from non- cellulosic fractions, said non-cellulosic fractions comprising at least one of thermoplastic polymer and metallic foil, comprising: (a) vigorously admixing paper product in aqueous solution in a vessel, said paper product being in a comminuted form and said vessel being such that the solution has a surface within the vessel, said admixing being effective for at least partial separation of cellulosic fibres from thermoplastic polymer and metallic foil and to form a suspension of cellulosic fibres so separated in the aqueous solution; and (b) separating a fraction comprised of at least one of thermoplastic polymer and metallic foil from the surface of said aqueous solution in the vessel using a bucket conveyer, said bucket conveyer extending below the surface of the aqueous solution and discharging the fraction so separated outside of said vessel. In a preferred embodiment of the process of the invention, the bucket conveyer has buckets with orifices therein attached to a conveyer belt. In another preferred embodiment of the process of the invention, the bucket conveyer has at least two tynes extending from a conveyer belt, especially 3-6 tynes. In another embodiment, the paper product is comminuted prior to being fed to the vessel, and in particular is in a shredded form. In yet another embodiment, the paper product is comminuted in the vessel, and in particular the vessel is a pulper vessel. In a further embodiment, the aqueous solution has a substantially neutral or alkaline pH, the latter including a pH of at least 9.5. In still another embodiment, the fraction separated from the surface of the aqueous solution is washed to separate cellulosic fibres from said fraction, the cellulosic fibres being optionally combined with the aqueous solution from the vessel. In another embodiment, solution passing from the vessel is passed to a screen having a mesh size to effect separation of thermoplastic polymer and metallic foil from cellulosic fibres, solution with cellulosic fibres passing through the screen, and then subjected to at least two hydrocyclone cleaners, the first of said hydrocyclone cleaners being adapted for rejection of material heavier than cellulosic fibres and the second of the hydrocyclone cleaners being adapted for rejection of material lighter than cellulosic fibres. In a further embodiment, the solution is alkaline and contains potassium hydroxide and/or sodium hydroxide. In a still further embodiment, the foil is aluminum foil. DETAILED DESCRIPTION OF THE INVENTION The present invention is illustrated by the embodiments shown in the drawings, in which: Fig. 1 is a schematic representation of the process of the invention; Fig. 2 is a schematic representation of a process utilizing the process of the invention; and Fig. 3A and 3B are schematic representations of scoops for the bucket conveyer. The present invention is generally described herein with reference to the metallic foil being aluminum foil. Other metallic foils may be used. In the embodiment of the invention illustrated in Fig. 1, the process is generally indicated by 1. Vessel 2 contains aqueous solution 3 that is stirred by stirrer 4. Paper product is fed to aqueous solution 3 through feed inlet 5. A bucket conveyer, generally indicated by 6, has conveyer belt 7 passing around upper drive wheel 8 and lower drive wheel 9. Conveyer belt 7 has a plurality of scoops 10 located thereon. Conveyer 6 is located so that scoops 10 pass beneath surface 11 of aqueous solution 3 in vessel 2, for removal of material therefrom. Scoops 10 would normally be fabricated to retain thermoplastic polymer and/or metallic foil components but pass aqueous solution and cellulosic fibres. In particular, the scoops 10 of bucket conveyer 6 may be in the form of a bucket with orifices or mesh in the bottom thereof, with the size of the orifices or mesh being large e.g. at least about 2.5 cm in size and especially in the range of about 2.5-6 cm in size. Alternatively, the scoops of the bucket conveyer may be in the form of tynes. Although a single tyne could be used in some circumstances, at least two tynes should be used and especially 3-6 tynes. Such tynes may be spaced apart by at least 2.5 cm and especially 2.5-6 cm. Other shapes of scoops may be used. Tynes are preferred. It is understood that the pieces of thermoplastic polymer and/or metallic foil that are removed with the bucket conveyer may be relatively large e.g. have dimensions of several centimeters in one or more directions, and it is intended that the bucket conveyer remove at least a substantial proportion of such pieces from pulper vessel 2. Upper drive 8 of bucket conveyer 6 is located above transfer conveyer 12, such that material from scoops 10 of bucket conveyer 6 can fall onto the surface thereof. Such material is indicated by 13. The discharge end 14 of transfer conveyer 12 is located above wash vessel 15. Wash vessel 15 has outlet 23 located in the upper section thereof and fluid outlet 17 in the bottom. Water inlets 16 are located above wash vessel 15. Outlet 18 in vessel 2 is connected by pipe 19 and inlet 20 to vessel 21. Fluid outlet 22 passes fluid from vessel 21. In operation, paper product is fed through inlet 5 to vessel 2. The paper product may be in a comminuted form, especially in a shredded form e.g. if the paper product is absorbent sanitary paper product. In that event, stirrer 8 is used to vigorously admix aqueous solution 3. If the paper product is not in comminuted form or if further comminution would be beneficial, stirrer 8 would be of a type that effects comminution of the paper product e.g. vessel 2 could be a pulper and stirrer 8 could be pulper knives. Vessel 2 is operated so that paper product therein is in a form that permits removal of thermoplastic polymer and/or metallic foil by the bucket conveyer. Similarly, scoops 10 are cooperatively designed. Bucket conveyer 6 is operated to remove thermoplastic polymer and/or metallic foil from the surface of aqueous solution 3. The polymer and foil is then deposited onto transfer conveyer 12 and subsequently into wash vessel 15. The thermoplastic polymer and metallic foil is washed in wash vessel 15, using water inlets 16, especially to flush cellulosic fibre from the thermoplastic polymer and foil. Aqueous solution and cellulosic fibre passes from wash vessel 15 through outlet 17, and in the embodiment shown is fed to vessel 21. Vessel 21 also receives aqueous solution and cellulosic fibre from vessel 2 through transfer pipe 18. It is understood that aqueous solution in vessel 21 will contain thermoplastic polymer and metallic foil, especially such components in relatively small particle size, received from both vessel 2 through transfer pipe 19 and from wash vessel 15. Solution passing from vessel 21 would normally be subjected to further processing for recovery of components therein, especially cellulosic fibres, for example using the method discussed below. Thermoplastic polymer and metallic foil passing from outlet 23 may be subjected to further processing to separately recover the polymer and metal. Fig. 2 illustrates a method of treating cellulosic fibre solution passing from vessel 21. Solution is passed from vessel 21 through outlet 22 to first screen vessel 24, which has coarse screen 25. On the upstream side of coarse screen 25 is discharge outlet 26 for the discharge of large particles i.e. particles not passing through coarse screen 25, into bin 27. On the downstream side of first screen vessel 24 is transfer line 28 for the discharge of solution passing through coarse screen 25. Transfer line 28 passes solution into the upstream of second screen vessel 29. Second screen vessel 29 has a discharge outlet 30 on the upstream side of fine screen 31 into bin 32 for particles that will not pass through fine screen 31. The downstream side of fine screen 31 is connected to transfer line 33. Transfer line 33 is connected to a hydrocyclone cleaner that is referred to herein as a Posiflow cleaner 34, the discharge of heavy particles from Posiflow cleaner 34 occurs through discharge outlet 35. Solution with lighter particles is discharged from Posiflow cleaner 34 through transfer line 36 to the inlet of a hydrocyclone cleaner that is referred to herein as a Uniflow cleaner 37. In operation of the embodiment of Fig. 2, solution is continuously passed through transfer line 22 into first stream vessel 24, in which large particles of thermoplastic material, usually essentially in the form of thermoplastic film, and pieces of metallic foil are separated as these are not passed through coarse screen 25. These large particles would be particles that the bucket conveyer has failed to scoop from the top of aqueous solution 3. The mesh size of coarse screen 25 is selected to effect such a separation. Cellulosic fibres and solutions pass through coarse screen 25 and are transferred into transfer line 28 into second screen vessel 29. Second screen vessel 29 has the screen of a smaller mesh size than that of first screen vessel 24. Further separation of thermoplastic polymer and metallic foil particles is effected in second screened vessel 29. Second screen vessel 29 effects a separation of pieces of thermoplastic film and metallic foil that were small enough to pass through coarse screen 25. These particles of thermoplastic film and metallic foil had discharged from the upstream side of fine screen 31 into bin 32. Cellulosic fibre and solution pass through fine screen 31 and our transferred through transfer line 33 into Posiflow cleaner 34. Posiflow cleaner 34 effects a separation of dense particles from the solution, which are discharged through discharge outlet 35. The bulk of the solution, containing the cellulosic fibres is passed through transfer line 36 to the inlet of Uniflow cleaner 37. Uniflow cleaner 37 effects a separation of low density particles from the solution, through discharge outlet 38. Again the bulk of the solution passes through transfer line 39 into separator 40. Separator 40 effects a separation of solution from cellulosic fibres. In a particular embodiment, separator 40 is known as a dynamic washer, which effects both separation of the cellulosic fibres and the washing of those fibres, which are discharged through upstream outlet 43. Fig. 3A shows a section of a bucket conveyer, having conveyer belt 60 with bucket 61 thereon. Bucket 61 is attached to conveyer belt 60 by bolts 62. Scoop 61 is in the form of a bucket, having a base 63. Base 63 of bucket 61 has a plurality of orifices 64. As discussed herein, the orifices should have a diameter of at least about 2.5 cm and especially about 2.5-6 cm. While Fig. 3A shows a bucket with orifices in the bottom thereof, it is understood that the bucket could have a mesh in the bottom thereof. Fig. 3B shows conveyer belt 60 having base plat 65 attached thereto by bolts 66. Base 65 has tynes 67 extending therefrom. In the embodiment shown in Fig. 3B, four tynes 67 are shown, although the number of tynes could be two or more, as discussed herein. Tynes 67 should be spaced apart by at least about 2.5 cm and especially about 2.5-6 cm, as discussed herein. The invention has been particularly described herein the reference to the use of a bucket conveyer to separate thermoplastic polymer and/or metallic foil from the surface of the aqueous solution. While this is the preferred method, other skimming devices, weirs or baffles could be used. As discussed above, the paper product may be coated paperboard. The paperboard is coated on a least one side with at least one of thermoplastic polymer and metallic foil. The thickness of the paperboard will vary depending on the particular end use of the coated paperboard. However, in the beverage and juice packaging industries, typical thicknesses are in the range of about 175 to about 450 g/m. The thermoplastic polymer coating will normally be a heat sealable coating, at least the outer coating will normally be heat sealable for ease of fabrication of the beverage or juice container. Such coatings may be a polyolefin e.g. polyethylene, polypropylene, ethylene copolymers e.g. ethylene/vinyl acetate copolymers and the like, and would comply with health and other regulations for packaging of foodstuffs. The metallic foil is normally used as a barrier layer, and be interposed between layers of the thermoplastic polymer, or between thermoplastic polymer and a layer for the bonding of the foil to the cellulosic layer i.e. the paperboard. The metallic foil will usually be aluminum foil. Another example of the paper product is absorbent sanitary paper product. Examples of the construction of such product has been described above. The process may be operated with the aqueous solution in vessel 2 at substantially neutral pH or at alkaline pH. The pH of solutions in subsequent steps in the process will generally tend towards a neutral pH, due to washing procedures or addition of water. Substantially neutral pH is intended to mean the pH obtained by use of municipal water, or other similar water, which will likely to be at a slightly acidic pH in the pulper due to residual amounts of liquid in the coated paperboard especially where the coated paperboard is in the form of juice boxes which can contain residual amounts of e.g. orange juice. Substantially neutral pH is preferred, especially for economic and environmental reasons. Alkaline pH's may be used, including a pH of at least 9.5, and preferably at least 10. This solution is preferably formed from an alkali metallic hydroxide, especially sodium and/or potassium hydroxides. Sodium hydroxide is preferred. Techniques for removal of SAP from processes of the type described herein have been described in the aforementioned PCT application of M.E. Conway et al. Such techniques may be embodied in the aqueous solution used herein. In its overall context, the present invention will permit a recycling system that would involve the collection of paper products, especially in the form of beverage boxes, disposable diapers, incontinence products and feminine hygiene products, and the like after use, in thermoplastic bags or other suitable collection containers, including a polyethylene bag, from households, institutions, hotels and the like. The paper products would then be transported to a processing facility for treatment according to the process of the present invention. Cellulosic material obtained from the process of the invention is relatively un-degraded and un-refined material, compared to cellulosic material that has been subjected to processes for the manufacture of paper, tissue or towelling. In addition, the cellulosic material may be cleaner, i.e. whiter, than cellulosic material obtainable from many other sources. It has potential for use in a wide variety of end uses, including recycling back into diaper and beverage box manufacturing processes. Many of the solutions used in the process may be treated for recovery of components, reused in the process, or in other processes. For example, the alkali metallic hydroxide solution may be recycled from separator 27 back into pulper vessel 2. The hydrocyclone cleaners referred to above have been described with respect to Fig. 1 as being Posiflow cleaners 21 and Uniflow cleaner 25, both of which are obtainable from the Beloit Jones Division of Beloit Corporation, Dalton, Mass., U.S.A.. The former type of hydrocyclone cleaner effects removal of heavy particulate matter and the latter effects removal of lighter particulate matter. It is understood that a plurality of hydrocyclone cleaners may be used, both of the Posiflow cleaner type and of the Uniflow cleaner type. Each type of hydrocyclone cleaner may be used in parallel with similar hydrocyclone cleaners and/or in series with similar hydrocyclone cleaners in order to more effectively separate heavy and light matter. It is understood that vessels may be inserted into any stage of the process in order to control the rate of flow of solution through the process. This is likely to be particularly important if any stage of the process is operated in a batch mode. The paper product fed to the aqueous solution may be in a comminuted form. In particular, the paper product may be shredded. However, if the paper product is in a fine particle form, such particles would be more difficult to remove using the bucket conveyer, thereby possibly causing process complications in subsequent steps in the process. Suitable selection of the buckets of bucket conveyers can alleviate this potential problem. It is preferred, if the coated paperboard is comminuted prior to feeding to the solution, that the particles be relatively large to facilitate removal either on the first screen or more preferably using the bucket conveyer as described above. In an embodiment of the invention, the paper product is fed to the aqueous solution without being comminuted, with the first vessel then being in the form of a pulper equipped with rotating knives to effect the breakdown of the paper product into smaller pieces. Such a use of a pulper has been found to be a useful way of obtaining the paper product, especially coated paperboard in a suitable size to effect the separations described herein. Admixing should not be so vigorous as to cause thermoplastic polymer and metallic foil pieces to be pulled down from the surface of the vessel into the bulk of the solution, thereby making separation using a bucket conveyer more difficult. It is possible to increase the amount of paper product in the aqueous solution to an extent such that on pulping or agitation, the particles of thermoplastic polymer and metallic foil become immersed within the solution in a relatively uniform manner. If the amount of paper product in the aqueous solution is reduced, the thermoplastic polymer and metallic foil tends to accumulate at the top of the aqueous solution, thereby facilitating removal. It is preferred that the process be operated such that there are some natural separation of cellulosic fibres and from the less dense thermoplastic polymer and metallic foil in the aqueous solution. The use of the lower concentrations will also facilitate subsequent processing of the materials. It is preferred that the pulped solution contain 3-12% pulp, sometimes referred to herein as a consistency of 3-12%, more preferably 3-10% pulp and especially 5-6% pulp. The actual apparatus used will have an effect on the preferred consistency. In addition, the pulping should be operated such that the amount of film and aluminum foil fed to the hydrocylones, as described herein, is not more than 10% of the amount of cellulosic fibres, especially not more than 7% by weight. Preferred amounts are 4-6% by weight. The composition of the pulp will depend on the nature of the coated paperboard fed to the process. For instance, if the coated paperboard is juice boxes, the pulp may contain about 55% cellulosic fibre, about 40% plastic and 5% aluminum. Other coated paperboard will have different amounts of cellulosic fibre, plastic and aluminum. Some coated paperboard will not contain aluminum or other metallic foil. The ratio of cellulosic fibre to plastic may vary over a wide range. Such wide variations in the ratio of cellulosic fibre : plastic : aluminum foil are acceptable, and the ratio in an operating process is likely to vary considerably with time, depending on the origin of the feedstock. In an embodiment of the present invention, especially when printed products are fed to the process, the solution is subjected to one or more steps to remove ink. This may be accomplished using a pressurized de- inking module, which is obtainable from the Beloit Jones Division of Beloit Corporation, Dalton, Mass., U.S.A. Such a pressurized de-inking module would normally be inserted in the process subsequent to the screen used to separate fine particulate matter. One or more pressurized de-inking modules may be used. Such a use of a pressurized de-inking module will result in the production of cellulosic fibres of improved colour, particularly when the paper product contains inks. In embodiments of the invention, the first screen in the process has a mesh size in the range of 0.025-0.055 inches, especially in the range of 0.035-0.045 inches. It is preferred that any second screen in the process has a mesh size in the range of 0.006-0.012 inches. Although the first screen may be used for separation of thermoplastic polymer and metallic foil of relatively large size, such separation is secondary to that of the bucket conveyer, as described above. The vessel shown is vessel 16 in Fig. 1 may be a vessel of a type known as a trommel or used in conjunction with a trommel. Such vessels are used to accomplish both separation and washing of the material passing through the vessel. It is to be understood that immediately prior to separator 40, shown in Fig. 2, the cellulosic fibres may be subjected to steps for brightening, washing and/or treatment with disinfectant in order to improve the quality of the product being obtained and/or to meet various governmental regulations. If the metallic foil component is aluminium, which is commonly used in packaging, then the aluminium may be separated from thermoplastic polymer using, for example, alkaline solutions. Alternatively, the polymer could be burnt off the foil. The thermoplastic material, which is normally a polyolefin, may be used in a variety of end uses. The present invention is illustrated by the following examples: EXAMPLE I Beverage boxes were received from institutions. These boxes contained straws and unconsumed juices. The boxes were fed to a pulper and pulped in aqueous solution for about 30 minutes. The pulping was carried out in a manner such that pieces of thermoplastic polymer and metallic foil floated to the top of the solution. These pieces were removed using a bucket conveyer, washed in a trommel to remove free cellulosic fibres and then baled. The bales contained approximately 93% thermoplastic polymer, 5% aluminum foil and 2% cellulosic fibres. In contrast, juice boxes typically contain about 20% thermoplastic polymer, 5% aluminum foil and 75% cellulosic fibres. The solution from the pulper was combined with the cellulosic fibres from the trommel, and then subjected to a coarse screen with a mesh size of 0.035 inches and then a fine screen with a mesh size of 0.006 inches. Solution passing through the fine screen was subjected to a hydrocyclone to remove heavy particulate, and then a pressurized de-inking module to remove ink and other particulate. The solution was then subjected to hydrocyclones to remove heavy and then lightweight particulate matter, brightened and washed. The cellulosic fibre separated from the process was white and of good quality, suitable for recycling as tissue-grade or fine paper-grade fibre. EXAMPLE II Approximately 63,500 pounds of juice boxes and milk cartons, being in the form of polyethylene-coated cardboard or polyethylene and aluminum foil-coated cardboard, were fed to a process of the invention. The juice boxes were fed in 28 separate loads with an average weight of approximately 1300 pounds, and for these boxes a pulping time of 32 minutes was used. The milk cartons were fed in 19 separate loads at an average weight of 1260 pounds per load with an average pulping time of 49 minutes. One further load of mixed juice boxes and milk cartons weighing approximately 1300 pounds was also fed to the process, with a pulp time of 30 minutes. In all batches processed, the pulp consistency was approximately 5-5.5% by weight of the aqueous solution. The process was operated at substantially neutral pH i.e. municipal water was used without addition of alkali. The process was also operated at ambient temperature. The boxes were pulped and processed using a process of the type shown in Fig. 1. The knives used in the pulper were of a type referred to herein as shark knives. Solution passing from the pulper was subjected to a course screen with a mesh size of 0.035 inches and then to a fine screen with a mesh size of 0.010 inches. Solution passing from the fine screen was subjected to a pressurized de-inking module for removal of fine particulate matter, including fine plastic material, aluminum foil and ink. The solution was then subjected to hydrocyclones to remove heavy and then lightweight particulate matter, and then to brightening and washing steps. The cellulosic fibre separated from the process was found, on visual inspection, to be white and of good quality. Visual inspection also showed that plastic and aluminum foil had been separated effectively from the cellulosic fibre. This example shows that the process is capable of being operated on substantial quantities of juice boxes and milk cartons.

Claims: CLAIMS : 1. A process for the separation of cellulosic fibres from non-cellulosic fractions in paper product, said paper product comprising cellulosic fibres and at least one of thermoplastic polymer and metallic foil, comprising: (a) vigorously admixing paper product in aqueous solution in a vessel, said paper product being in a comminuted form and said vessel being such that the solution has a surface within the vessel, said admixing being effective for at least partial separation of cellulosic fibres from thermoplastic polymer and metallic foil and to form a suspension of cellulosic fibres so separated in the aqueous solution; and (b) separating a fraction comprised of at least one of thermoplastic polymer and metallic foil from the surface of said aqueous solution in the vessel by using a bucket conveyer, said bucket conveyer extending below the surface of the aqueous solution and discharging the fraction so separated outside of said vessel. 2. The process of Claim 1 in which the bucket conveyer has buckets with orifices therein attached to a conveyer belt. 3. The process of Claim 1 in which the bucket conveyer has at least two tynes extending from a conveyer belt. 4. The process of Claim 3 in which there are 3- 6 tynes. 5. The process of any one of Claims 1-4 in which the paper product is comminuted prior to being fed to the vessel. 6. The process of Claim 5 in which the paper product is in a shredded form. 7. The process of any one of Claims 1-4 in which the paper product is comminuted in the vessel. 8. The process of Claim 7 in which the vessel is a pulper vessel. 9. The process of any one of Claims 1-8 in which the aqueous solution has a substantially neutral or alkaline pH. 10. The process of any one of Claims 1-8 in which the aqueous solution has a substantially neutral pH. 11. The process of any one of Claims 1-8 in which the aqueous solution has a pH of at least 9.5. 12. The process of any one of Claims l-ll in which the fraction separated from the surface of the aqueous solution is washed to separate cellulosic fibres from said fraction. 13. The process of Claim 12 in which the cellulosic fibres obtained are combined with the aqueous solution from the vessel. 14. The process of any one of Claims 1-13 in which solution passing from the vessel is passed to a screen having a mesh size to effect separation of thermoplastic polymer and metallic foil from cellulosic fibres, solution with cellulosic fibres passing through the screen, and then subjected to at least two hydrocyclone cleaners, the first of said hydrocyclone cleaners being adapted for rejection of material heavier than cellulosic fibres and the second of the hydrocyclone cleaners being adapted for rejection of material lighter than cellulosic fibres. 15. The process of any one of Claims 1-14 in which the solution contains potassium hydroxide and/or sodium hydroxide. 16. The process of any one of Claims 1-15 in which the foil is aluminum foil.

Inventors: CONWAY MARLENE ELIZABETH, MARTIN SCOTT ANTONY, CONWAY, MARLENE, ELIZABETH, MARTIN, SCOTT, ANTONY
Applicants: CONWAY MARLENE ELIZABETH, KNOWASTE TECH INC, MARTIN SCOTT ANTONY, CONWAY, MARLENE, ELIZABETH, KNOWASTE TECHNOLOGIES INC., MARTIN, SCOTT, ANTONY
Application year: 1995
Main classification: D21B1
IPC codes: D21B1, D21D5