GB2597999A

GB2597999A - Product and method

Info

Publication number: GB2597999A
Application number: GB2012754.4A
Authority: GB
Inventors: Ford Andrew
Original assignee: Pets Choice Ltd
Current assignee: Pets Choice Ltd
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2022-02-16
Anticipated expiration: 2040-08-14
Also published as: GB202012754D0; GB2597999B

Abstract

A pelletised cat litter product is made from reprocessed paper sludge waste, such as recovered virgin or primary sludge generated during paper manufacture or de-inked paper sludge produced from recycled paper, to which may be added: granules or powder of a clay-based mineral, such as bentonite, attapulgite (Palgorskite clay) and calcium silicate, for example in the form of cement dust extractor waste recovered from process dust extractors; and an absorbent additive such as recycled cellulose-based products like paper fibres, recycled paper, shredded paper, wood dust, wood flour, wood particles, fluff wood pulp or a fluff pulp recovered from the waste stream of a disposable personal hygiene product, nappy or diaper manufacturing process and mixed with other fibres; and an absorbent polymer-based product including superabsorbent polymers (SAPs) which may be also recovered from the manufacturing process waste stream. Water 106 is added to the mixture 100,102,104 which is then mixed 108, extruded 110 and dried 112 to produce pellets.

Description

PRODUCT AND METHOD

TECHNICAL FIELD

This invention relates to a cat litter product and a method of manufacturing. In particular, the invention relates to a pelletised cat litter product and method of manufacturing.

BACKGROUND

A litter tray, also known as a litter box, sand box, cat box, cat pan or litter pan is a container for collecting faeces and urine for small animals, typically cats but also other animals such as rabbits, ferrets, miniature pigs and small dogs. Litter trays are filled with cat litter, a material that absorbs liquids and optionally odours.

Cat litter is available in a variety of different forms, such as clay, silicon-based crystals and cellulose based litter.

Clumping cat litter is made from granules which clump together when wet, forming a solid mass separate from the surrounding litter. These clumps can easily be removed from the litter tray. One type of clumping cat litter is made from bentonite clay, which is highly 15 absorbent.

Whilst cat litter made from bentonite clay is highly effective, it has the disadvantage that it is produced by mining, as opposed to from a recyclable source.

The pulp and paper industry generates a large amount of solid waste. Natural cellulose fibres give paper strength, flexibility and are readily wetted by water, all of which are valuable properties for paper manufacture. Fibres in paper and cardboard can be recycled several times. However, once the fibres become too short, they are no longer suitable for making paper and cardboard, which typically occurs when they have been recycled several times.

The fibres discarded in the pulping process end up in sludge called paper sludge.

During the recycling process, cardboard and paper is "slushed" into pulp and large non-fibrous contaminants are removed (for example staples, plastic, glass etc). The fibres are progressively cleaned, and the resulting pulp is filtered and screened a number of times to make it suitable for paper making. Fibres which are discarded in the pulping process end in a sludge called paper sludge.

It is an object of the invention to provide a cat litter product which overcomes the disadvantages of the prior art.

SUMMARY OF THE INVENTION

An aspect of the invention provides a cat litter product, comprising: a substance formed into pellets, wherein the substance comprises paper sludge waste.

The paper sludge waste may comprise cellulose fibres. The fibres in paper sludge waste are not long enough for the papermaking process, as they are no longer capable of making the lattice structure for paper. The fibres typically have a length of.s about 1.5mm. The fibres may have a length of S about lmm, or a length of about 0.8mm, or a length of about 0.6mm. The fibres may have a length of about 0.5mm. In one embodiment, fibres have a length of between 0.3 and 0.4mm, for example, the fibres may have a length of between 0.3 and 0.35mm.

The paper sludge waste may comprise both organic matter and non-organic matter. The organic matter may comprise short cellulose fibres. The non-organic matter (also known as ash) typically comprises fillers such as kaolinite (clay) and calcium carbonate. The paper sludge waste may comprise 40-50% cellulose fibres. In one embodiment, the sludge waste comprises about 30% cellulose fibres.

The paper sludge waste may comprise virgin paper sludge waste, also known as primary sludge. For example, virgin paper sludge waste may comprise the waste generated during paper manufacture, e.g. from paper mills, or from the production of virgin wood fibre.

The paper sludge waste may comprise de-inked paper sludge. For example, de-inked paper sludge may be produced from recycled paper, which has been processed to remove inks, coatings, sizing adhesives or other properties. The paper sludge may be subjected to a froth flotation process which produced de-inked sludge.

The substance may comprise extractor waste from a dust extractor.

Dust extractors, also known as dust collectors, are used to recover granular solid or powder from process streams and to remove granular solid pollutants from exhaust gases prior to venting to the atmosphere. Examples of dust extractors include inertial separators (such as centrifugal collectors), fabric filters, wet scrubbers, unit collectors and electrostatic precipitators.

The extractor waste may comprise a mineral. In one embodiment, the extractor waste comprises a mineral selected from one or more of bentonite, attapulgite (Palgorskite clay) and calcium silicate, for example in the form of cement dust.

The extractor waste may comprise granules or powder. The extractor waste may have a particle size of about 250 microns.

The substance may comprise an additive, for example an absorbent additive. The additive may have a greater absorbency than paper sludge waste. The additive may have an absorbency of about 90%, or an absorbency of about 100%, or an absorbency of about 110%, or an absorbency of about 120%, or an absorbency of about 130%, or an absorbency of about 140%, or an absorbency of about 150%, or an absorbency of about 160%, or an absorbency of about 160%, or an absorbency of about 170%, or an absorbency of about 180%, or an absorbency of about 190%. Alternatively, the additive may have a lower absorbency than paper sludge waste. The additive may have alternative functions, such as odour control.

The additive may have a bulk density less than the bulk density of paper sludge waste. The additive may have a bulk density of about 0.7 kg/L, or a bulk density of,about 0.6 kg/L, or a bulk density of about 0.5 kg/L. The additive may have a bulk density of about 0.5 kg/L, or a bulk density of about 0.6 kg/L. Alternatively the additive may have a bulk density substantially equal to or more than the bulk density of paper sludge waste.

The additive may comprise a recycled additive. For example, the additive may be recovered from a processing plant using the additive.

The additive may be selected from a cellulose-based product and a polymer-based product.

Examples of cellulose-based products include paper-based products, for example in the form of paper pulp, and wood-based products, for example in the form of fluff wood pulp and wood dust/wood flour or wood particulates below 2mm. These cellulose-based products may be recycled, for example from waste from manufacturing processes.

Examples of polymer-based products includes super absorbent polymers (SAP).

In one embodiment, the additive is in the form of recycled paper. The recycled paper may be in the form of recovered paper pulp or shredded paper, for example tissue paper, kitchen roll, toilet paper etc. Recovered paper pulp is a pulp created from paper that has been recovered for recycling. Recovered pulp is made by combining the recovered paper with water in a pump that acts as a blender to separate and mix the fibres into a slurry. Suitable sources of wastepaper include recycled paper from office and domestic sources, waste from paper mills, etc. The recovered pulp may be de-inked. De-inked recovered pulp is recovered pulp which has been processed to remove inks, coatings, sizing adhesives or other properties.

Pulp is made from breaking down either wood chips or paper recovered from recycling. Fluff pulp is widely used as an absorbent medium in disposable personal hygiene products, such as diapers/nappies and feminine hygiene products. Fluff pulp, also known as fluffing or comminution pulp, is typically manufactured from pulp which undergoes a chemical, mechanical or combined chemical/mechanical process. Fluff pulp is typically made from long fibre softwoods.

In one embodiment, the fluff pulp comprises recycled fluff pulp. The recycled fluff pulp may be recovered from a waste stream, for example from a personal hygiene products processing plant. The fluff pulp may be mixed with other fibres, for example polyester, polypropylene Nylon, Rayon, SAPs. The recycled fluff pulp may be in the form of a powder or slurry.

The IUPAC definition of a superabsorbent polymer (SAP) is a polymer that can absorb and retain extremely large amounts of a liquid relative to its own mass. SAPs typically hold between 50 and 500 times their own weight, depending on the liquid they absorb. SAPs absorb aqueous solutions through hydrogen bonding with water molecules and are classified as hydrogels when mixed. They are typically used in disposable personal hygiene products, such as baby diapers/nappies, adult continence products and feminine hygiene products, horticultural water retention agents, control of spill and waste aqueous fluid. Commonly used SAPS include sodium polyacrylate, potassium polyacrylate and carboxy methyl cellulose (CMC).

The SAP may comprise a recycled SAP. For example, the SAP may be recovered from the waste stream of a manufacturing process, for example from a disposable personal hygiene product manufacturing process.

The substance may comprise at least 50% weight of paper sludge waste, or at least 60% weight of paper sludge waste, or at least 70% weight of paper sludge waste, or at least 80°k weight of paper sludge waste, or at least 90% weight of paper sludge waste, or 100% weight of paper sludge waste.

The substance may comprise at least 5% of extractor waste, or at least 10% of extractor waste, or at least 1 5 % of extractor waste, or at least 20% extractor waste, or at least 2 5 % of extractor waste, or at least 30% extractor waste.

The substance may comprise at least 5°/a of additive, or at least 10% of additive, or at least 15% of additive, or at least 20% of additive, or at least 25% of additive, or at least 30% of additive.

In one embodiment, the substance comprises 100% recycled components. For example, the substance may comprise paper sludge waste, extractor waste and recycled additive.

An aspect of the present invention provides a method for manufacturing a cat litter product comprises the steps of: (a) providing a substance comprising paper sludge waste; (b) forming a mixture by mixing the substance with water; (c) forming the mixture into pellets; and (d) drying the pellets.

The step of forming the mixture into pellets may comprise passing the mixture through an extruder.

The paper sludge waste may comprise cellulose fibres, the fibres typically have a length of about 1.5mm. The fibres may have a length of about lmm, or a length of about 0.8mm, or a length of about 0.6mm The substance may further comprise extractor waste.

The substance may further comprise an additive, having an absorbency greater than the absorbency of paper sludge waste.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", mean "including but not limited to", and do not exclude other components, integers or steps. Moreover the singular encompasses the plural unless the context otherwise requires: in particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Preferred features of each aspect of the invention may be as described in connection with any of the other aspects. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration illustrating the production of waste paper sludge; and Figure 1 is schematic illustration illustrating a method of manufacturing cat litter according to an embodiment.

DETAILED DESCRIPTION

Paper sludge waste is the name for the residue from the paper making process. An overview of the process for generating paper sludge from the wastewater stream of a paper making process is illustrated in Fig 1.

Wastewater 10 from the paper making process passes through primary and secondary clarifiers 20,30, which produce primary and secondary sludge 40,50 respectively. The clarified effluent 60 output from the secondary clarifier 50 undergoes further treatment steps (not shown) before being discharged to the sewage network.

The primary and secondary sludge 40,50 undergo a dewatering process 70, in which the solids/residues are settled in large settlement tanks. This is followed by a thickening process, which uses presses to increase the solid content of the resulting sludge 80 to 5060%.

The recovered water 90 from the dewatering process is returned to the wastewater stream.

The exact composition of paper sludge waste will depend on the paper making process from which it is produced. However, a typical composition is 30% organic matter, such as short cellulose fibres and 70% non-organic matter (also known as ash), such as kaolinite (clay) and calcium carbonate.

The method of manufacturing the cat litter product will now be described with reference to Fig 2.

In a first step 100, the paper sludge waste is added to a mixer. The paper sludge waste is sourced from the waste stream of paper processing mills. The paper sludge waste may comprise virgin or de-inked paper sludge. The paper sludge waste typically has a water content of 5%-60% and may comprise organic matter, such as short cellulose fibres and non-organic matter (also called ash), such as fillers for example calcium carbonate and clay.

In a second optional step 102, extractor waste is added to the mixer. The extractor waste is the waste from the dust extractors in the processing plant, and typically comprises a mixture of bentonite, attapulgite and calcium silicate. The extractor waste is a powder and the particle size is dependent on the filters used but is typically about 250microns. The paper sludge waste and extractor waste are mixed to ensure that the mixture is homogenous.

In a third optional step 104, an additive is added to the mixer, for example super absorbent polymer (SAP), fluff pulp dust and/or recycled paper.

In a fourth step 106, water is added to the mixer. In a fifth step 108, the resulting mixture is mixed.

In a fifth step 1110, the mixture is passed through an extruder to form pellets.

In a sixth step 112, the pellets are dried, for example in a rotary drier. The resulting dried pellets are ready for packaging.

The method steps may be carried out in any order. For example, the paper sludge waste may be mixed with water in an initial step, with other constituents being added afterwards.

Water absorbency The water absorbency of the cat litter pellets was tested according to the following method, based on the Westinghouse method.

An 80g sample of cat litter is tested as follows: The cat litter sample is first mixed to ensure it is homogenous.

A clean and dry stainless steel 355pm mesh cone, 70mm diameter by 70mm height is weighed to the nearest 0.1 g (M1). 19.5 -20.5 g of sample is added to the cone and the cone and sample is weighed to the nearest 0.1 g (M2).

A 11 beaker is filled to the 1L mark with deionised water. A cone is lowered into the 1L beaker and soaked for 20 mins. After 20 mins, the cone is withdrawn from the 1L beaker and rested in a 100m1 beaker, where it is allowed to drain for 30 minutes. The combination of the cone and saturated sample is weighed to the nearest 0.1g (M3).

The water absorbency of each sample is calculated using the following equation.

M3-N12 (1) Absorbency (wt%) --*100 M2-M1 The result is the average absorbency of three tests.

Bulk density measurement procedure The bulk density of the cat litter was tested according to the following method.

A sample is taken of the cat litter product, with a typical sample size of 5-10kg.

A funnel is held over a beaker and, with the bottom of the funnel covered, material is poured into the funnel. The product is released into the beaker until the beaker is overflowing, and the excess material is scraped off the top of the beaker, using a level edge such as a ruler, without tapping or shaking. The volume of the beaker and the weight of the product in the beaker is recorded. This test is repeated 10 times.

To density of the sample is calculated using the following formula: Density -mi-MO (2) where: Pio is the mass, in grams, of the empty beaker Mt is the mass, in grams, of the beaker and its contents V is the volume, in millitres, of the beaker.

The average result of the 10 tests is multiplied by 100 and expressed in kg/L.

Example 1: 100% Paper sludge waste In this embodiment, the pellets were 100% paper sludge waste.

The paper sludge waste was sourced from the waste stream of paper processing mills. The cellulose particles within the paper sludge waste had a length 1.5mm. The waste paper sludge has a damp, crumb structure.

The paper sludge waste was mixed with water in a mixer and the resulting mixture passed through an extruder to form the pellets. The resulting pellets were dried in a rotary drier and then sent for packaging.

The pellets had a diameter of 4mm and a length of 8-20mm.

The absorbency and bulk density of the pellets were tested using the methods described above and the results are shown in Table 1 Example 2: 80% Paper sludge waste with 20% extractor waste dust In this example, the pellets were 80% paper sludge waste and 20% extractor waste.

The method of example 1 was followed. However, extractor waste was also added to produce a mixture of paper sludge waste, extractor waste and water. The paper sludge waste, extractor waste and water were mixed to ensure a homogenous mixture. The extractor waste dust was made up of bentonite, attapulgite and calcium silicate and had a particle size of 250 microns.

The resulting pellets had a diameter of 4mm and a length of 8-20mm.

The absorbency and bulk density of the pellets were tested using the methods described above and the results are shown in Table 1 Example 3: 70% Paper sludge waste, 20% extractor waste, 10% wood dust In this example, the pellets were 70% paper sludge waste, 20% extractor waste and 10% wood dust.

The method of example 2 was followed. However, wood dust was added to produce a mixture of paper sludge waste, extractor dust, wood dust and water.

The pellets had a diameter of 4mm and a length of 8-20mm.

The extractor waste dust was made up of bentonite, attapulgite and calcium silicate and had a particle size of 250 microns.

The wood dust was sourced from recycled wood and was in the form of a powder with an average particle size of less than 2mm.

The absorbency and bulk density of the pellets were tested using the methods described above and the results are shown in Table 1.

Example 4: 70% Paper sludge waste, 20% extractor waste, 10% SAP In this example, the pellets were 70% paper sludge waste, 20% extractor waste and 10% super absorbent polymer SAP.

The method of example 3 was followed. However, SAP was added in place of wood dust. The pellets had a diameter of 4mm and a length of 8-20mm.

The SAP was recovered from a disposable personal hygiene product processing plant. The recovered SAP is in the form of a fibre or powder. The recovered SAP included sodium polyacrylate, in addition to other fibres.

The absorbency and bulk density of the pellets were tested using the methods described above and the results are shown in Table 1 Example 5: 70% Paper sludge waste, 20% extractor waste, 10% tissue In this example, the pellets were 70% paper sludge waste, 20% extractor waste and 10% tissue.

The method of example 3 was followed. However, recycled tissue was added in place of wood dust.

The pellets had a diameter of 4mm and a length of 8-20mm.

The tissue was sourced from the waste stream of a tissue manufacturing process.

The absorbency and bulk density of the pellets were tested using the methods described above and the results are shown in Table 1 Example 6: Convention cat litter (100% bentonite clay) In this example, the cat litter was 1000/a bentonite clay) The absorbency and bulk density of the cat litter tested using the methods described above and the results are shown in Table 1 Pellet Composition Absorbency Bulk Density 100% Paper sludge waste >60% wt/wt 0.6 ± 20% kg/L 80% Paper sludge waste with 20% extractor waste >65% wt/wt 0.6 ± 20% kg/L 70% Paper sludge waste, 20% extractor waste, 10Wo wood dust >70% wt/wt 0.55 ± 20% kg/L 70% Paper sludge waste, 20% extractor waste, 10% SAP >100% wt/wt 0.5 ± 20% kg/L 70% Paper sludge waste, 20% extractor waste, 10% tissue >100% wt/wt 0.5 ± 20% kg/L Convention cat litter (100% bentonite clay) 90-100% wt/wt 1.0 ±20% kg/L Table 1: Absorbency and Bulk Density of different pellet compositions The 100% paper sludge waste and 80% paper sludge waste / 20% extractor waste products showed good absorbency, which compares favourably with conventional cat litter products. The inclusion of the extractor waste has little impact on the absorbency.

As shown in Table 1, the inclusion of 100/o wood dust or 10% SAP significantly increases both the absorbency and bulk density properties of the cat litter product.

In each of these examples, the cat litter has been found to have natural odour control.

The cat litter product according to the present invention has a low environmental impact, as it is manufactured from waste materials which would otherwise end up in landfill. The use of paper sludge waste eliminates the need to use imported mined materials such as bentonite and attapulgite.

Extractor waste can be incorporated into the cat litter, without negatively affecting the absorbency or bulk density. Thus, both the paper sludge waste and extractor waste and used in the cat litter product instead of being disposed of directly in landfill.

The addition of a relatively small amount of additive, for example in the form of paper, wood dust or SAP, has the benefit of improving the absorbency and bulk density of the cat litter. Furthermore, the use of recycled paper, wood dust or SAP in the cat litter product ensures these components have a further use in the cat litter product rather than being disposed of directly in landfill.

Claims

CLAIMS1. A cat litter product, comprising: a substance formed into pellets, wherein the substance comprises paper sludge waste.
2. A cat litter product according to claim 1, wherein the paper sludge waste comprises cellulose fibres, the fibres having a particle length of s about 0.5mm.
3. A cat litter product according to any of claims 1 or 2, wherein the paper sludge waste comprises primary sludge or de-inked paper sludge.
4. A cat litter product according to any preceding claim, wherein the substance comprises extractor waste from a dust extractor, optionally a mineral.
5. A cat litter product according to any of claims 3 and 4, wherein the extractor waste comprises a mineral selected from one or more of bentonite, attapulgite (Palgorskite clay) and calcium silicate.
6. A cat litter product according to any of claims 3 to 5, wherein the extractor waste has a particle size of s about 250microns.
7. A cat litter product according to any preceding claim, wherein the substance comprises an additive.
8. A cat litter product according to any preceding claim, wherein the additive has a greater absorbency than paper sludge waste.
9. A cat litter product according to any of claims 7 or 8, wherein the additive has an absorbency of about 90%.
10. A cat litter product according to any of claims 7 to 9, wherein the additive has a bulk density less than the bulk density of paper sludge waste.
11. A cat litter product according to any of claims 7 to 10, wherein the additive has a bulk density of S about 0.7kg/L.
12. A cat litter product according to any of claims 7 to 11, wherein the additive is a recycled product.
13. A cat litter product according to any of claims 7 to 12, wherein the additive is selected from a cellulose-based product and a polymer-based product.
14. A cat litter product according to any of claims 7 to 13, wherein the additive comprises one or more of paper fibres, fluff pulp, wood dust, and super absorbent polymer (SAP).
15. A cat litter product according to claim 14, wherein the one or more paper fibres, fluff pulp, wood dust and super absorbent polymer are recycled.
16. A cat litter product according to claim 15, wherein the paper fibres are de-inked.
17. A cat litter product according to any preceding claim, wherein the substance comprises at least 700/o weight of paper sludge waste.
18. A cat litter product according to any preceding claim, wherein the substance comprises at least 5% of extractor waste dust.
19. A cat litter product according to any preceding claim, wherein the substance comprises at least 5% of additive.
20. A cat litter product according to any preceding claim, wherein the substance comprises 100% recycled components.
21. A method for manufacturing a cat litter product comprises the steps of: (a) providing a substance comprising paper sludge waste; (b) forming a mixture by mixing the substance with water; (c) forming the mixture into pellets; and (d) drying the pellets.
22. A method according to claim 21, wherein the paper sludge waste comprises cellulose fibres, the fibres having a particle length of about 1.5mm.
23. A method according to any of claims 21 or 22, wherein the paper sludge waste comprises primary sludge or de-inked paper sludge.
24. A method according to any of claims 21-23, wherein the substance further comprises extractor waste.
25. A method according to any of claims 21-24, wherein the substance further comprises an additive, the additive optionally having an absorbency greater than the absorbency of paper sludge waste.