WO2012162839A1

WO2012162839A1 - Cellulosic absorbent, and method for producing same from paper sludge and a binder

Info

Publication number: WO2012162839A1
Application number: PCT/CA2012/050367
Authority: WO
Inventors: Isabelle Bolduc; Paul Jollez; Marie-cléo GRAVEL-LACROIX
Original assignee: 7905122 Canada Inc.; FERRON, Eric
Priority date: 2011-06-01
Filing date: 2012-06-01
Publication date: 2012-12-06
Also published as: CA2840025A1; CA2840025C

Abstract

The invention relates to an absorbent, e.g. for bedding, in the form of cellulosic particles, and to a method for manufacturing same. Said particles include a gelled binding agent and cellulosic fibers from paper sludge and/or from paper. The binding agent enables the cellulosic fibers to remain distributed within a matrix gel structure. The matrix structure can be coated with an agglomerating mixture including at least one surfactant and at least one agglomerating agent which are deposited, in layers, from an outer surface of the matrix structure. The coated particles are capable of agglomerating together in order to trap the material to be absorbed. Said particles can be used for bedding. The manufacturing method comprises mixing paper sludge and/or paper in order to form a paste, adding the binding agent so as to form a gelled paste, and converting the gelled paste into cellulosic particles.

Description

CELLULOSIC ABSORBER AND METHOD FOR PRODUCING SAME FROM PAPER MUD AND BINDER

FIELD OF THE INVENTION

The present invention relates to an absorbent and its method of manufacture. More particularly, the present invention relates to an absorbent, such as a litter, in the form of cellulosic particles comprising a binder and cellulosic fibers from paper sludge and / or paper.

STATE OF THE ART

The cellulose-based absorbents from the paper are generally obtained by a granulation process producing coarse-sized cylindrical granules. For example, Yesterday's News® commercially available cat litter pellets are 30 mm in length with an average diameter of 4.2 mm (Figure 1). Large granules are typically preferred to shorter, thinner granules which, through the use of shorter fibers, would be too fragile, with the risk of quickly turning into fine dust during the use phase.

Recycled paper granules are generally produced by a granulation process in which the recycled paper is to be moistened prior to granulation. For this, the paper is usually shredded by a mechanical defibrator and the water is subsequently added to the paper fiber to make a paste. Large granules are not optimal because the area available for absorption is reduced compared to that of smaller granules. In the case of absorbent litter for animals, the excretions then quickly reach the bottom of the container in which the absorbent litter granules are disposed and stagnate therein. Stagnant liquid in the bottom of the container takes time to be absorbed by the overlying granules. This time allows the liquid to develop undesirable odors when exposed to the surrounding air. In addition, the coarse texture of the paper granules does not please domestic cats who prefer the sensation of fine sand in their natural state. The currently existing cellulose-based granules have no or very few physical properties that allow them to agglomerate when in contact with a liquid material. Indeed, their low density and their coarse size represent an obstacle to this agglomeration. In addition, these granules are not very absorbent, light and therefore scatter easily during the use phase.

Another disadvantage of cellulosic absorbent litter granules is that there is no effective control of the rate of absorption of the liquid as well as the associated odors.

There is therefore a need for a technology providing at least one solution to one of the problems and / or disadvantages such as those mentioned above concerning the inefficient absorption of excretions and associated odors by absorbent granules of unsuitable geometry.

SUMMARY OF THE INVENTION

The present invention relates to an absorbent in the form of absorbent cellulosic particles. These particles can be covered with an agglomerating mixture to give them an agglomerating capacity.

According to one aspect of the invention, there is provided a litter comprising cellulosic particles capable of being contacted with a material, the absorbent cellulosic particles comprising:

a binder agent gelled to form a matrix structure; and

a plurality of cellulosic fibers distributed within the matrix structure; the cellulosic fibers being derived from paper sludge, paper or a combination thereof.

According to an optional aspect of the litter, paper sludge may include de-inking sludge.

According to another optional aspect of the litter, at least 50% by weight of the cellulosic fibers may be derived from de-inking sludge. Optionally, all of the cellulosic fibers may be from de-inking sludge. Again optionally, at least a portion of the cellulosic fibers may be derived from recycled paper.

According to another optional aspect of the litter, the cellulosic fibers can be distributed substantially uniformly within the matrix structure. Optionally, the cellulosic fibers may be substantially aligned along an axis of the matrix structure. Optionally, the cellulosic fibers may be sufficiently aligned to reduce or eliminate the presence of protrusions on a contact surface of the matrix structure.

According to another optional aspect of the litter, the cellulosic fibers may have a length of between 0.1 and 10 mm. Optionally, 5 to 50% of the cellulosic fibers may have a length of between 0.1 and 3.5 mm.

According to another optional aspect of the litter, the binder may include a component that is derived from an organic colloid. It may also include a constituent that is derived from an inorganic colloid. Optionally, the binding agent may include guar gum, galactomannan gum, xanthan gum, methylcellulose, hydroxypropyl methylcellulose, carboxymethylcellulose, corn starch, wheat starch, starch of cassava, potato starch, lignin, lignin derivatives or a combination thereof. Optionally, the binder may include a superabsorber comprising polyvinyl alcohol, a polyacrylate, pre-gelatinized wheat starch, pre-gelatinized corn starch or a combination thereof. Still optionally, the binder may be the superabsorbent.

According to another optional aspect of the litter, the binder may include a clay. Optionally, the cellulosic particles may include at most 25% by weight of clay relative to the total weight of the cellulosic particles. The clay may include calcium bentonite, sodium bentonite or a combination thereof.

According to another optional aspect of the litter, the cellulosic particles may have a concentration by weight of cellulosic fibers of between 50% and 75%, and a concentration by weight of the binding agent of not more than 20%.

According to another optional aspect of the litter, at least a portion of the absorbent cellulosic particles may include an agglomerating mixture distributed over a outer surface of the matrix structure so that the cellulosic particles can agglomerate in contact with the material. Optionally, the agglomerating mixture may include at least one surfactant and at least one agglomerating agent.

According to another optional aspect of the litter, the cellulosic particles may include a first layer comprising the at least one surfactant which is deposited on the outer surface of the matrix structure, and a second layer comprising the at least one agglomerating agent which is deposited on the first layer.

According to another optional aspect of the litter, the cellulosic particles may include a plurality of layers deposited successively from the outer surface of the matrix structure, each layer including the at least one surfactant or the at least one agglomerating agent.

According to another optional aspect of the litter, the at least one surfactant may include a first surfactant and a second surfactant. Cellulosic particles can include:

a first layer deposited on the outer surface of the matrix structure, the first layer comprising the first surfactant;

a second layer deposited on the first layer, the second layer comprising the at least one agglomerating agent; and

a third layer deposited on the second layer, the third layer comprising the second surfactant.

In another optional aspect of the litter, the at least one surfactant may include an ionic surfactant selected from the group consisting of sodium lauryl sulfate, polyethylene glycol p- (1,1,3,3-tetramethylbutyl) -phenyl ether, analogs thereof and mixtures thereof.

According to another optional aspect of the litter, the at least one surfactant may include a nonionic surfactant selected from the group consisting of primary alcohols, ethyl phenoxy poly ethoxy ethanol, analogs thereof and mixtures thereof. this.

According to another optional aspect of the litter, the at least one agglomerating agent may include guar gum, xanthan gum, carboxymethylcellulose, polyethylene oxide, analogs thereof, or mixtures thereof. According to another optional aspect of the litter, the cellulosic particles may include an odor control agent reducing or eliminating the release of odors that may result from the material. Optionally, the cellulosic particles may include a layer comprising the odor control agent. Optionally, the odor control agent may include a urease inhibiting agent.

According to another optional aspect of the litter, the cellulosic particles may include a penultimate layer comprising the odor control agent and a final layer comprising the at least one surfactant.

According to another optional aspect of the litter, the urease inhibiting agent may be chosen from the group comprising N (n-butyl) thiophosphoric triamide, cyclohexyl thiophosphoric triamide, N- (N-butyl) phosphoric triamide, cyclohexyl phosphoric triamide, N-aliphatic triamide and Ν, Ν-aliphatic phosphoric triamide, phosphorotriamides, 4-aminophenyl sulphonylamino phenyl phosphorodiamidates, N- (diaminophosphinyl) arylcarboxamines, polysulfides, ferric sulphate, thiosulphates, ricinoleates mixtures thereof and analogs thereof.

According to another optional aspect of the litter, the cellulosic particles may have a particle size of between 4 and 100 mesh.

According to another optional aspect of the litter, the cellulosic particles may have a particle size distribution in which at least 90% of the cellulosic particles have a particle size of between 4 and 60 mesh, and at most 10% of the cellulosic particles have a particle size of less than 100. mesh. Optionally, the cellulosic particles have a particle size distribution in which at least 95% of the cellulosic particles have a particle size of between 8 and 60 mesh, at most 5% at a particle size of less than 70 mesh and at most 2% of the cellulosic particles has a particle size of particle size less than 100 mesh.

According to another optional aspect of the litter, the cellulosic particles may have a density of between 15 and 40 lbs / ft ³ .

According to another optional aspect of the litter, the cellulosic particles may have a concentration by weight of cellulosic fibers of between 45 and 70%, a concentration by weight of the binding agent of at most 19% and a concentration by weight of agglomerating mixture of at most 7%.

According to another optional aspect of the litter, the cellulosic particles, when placed in contact with urine, can have a release of ammonia of between 0 and 25 ppm after 48 hours.

According to another optional aspect of the litter, the cellulosic particles may have a substantially cylindrical shape.

According to another optional aspect of the litter, the litter may include additional indicator particles that may change color upon contact with excretions, the indicator particles comprising a color former and an oxidizing agent. Optionally, the litter may include at least 99% cellulosic particles and at most 1% indicator particles. Optionally, litter may include 0.04% to 0.2% indicator particles.

According to another aspect of the present invention, there is provided a method of manufacturing a litter comprising absorbent cellulosic particles. The method includes the following steps:

mixing paper sludge and / or paper to form a wet paste comprising cellulosic fibers;

adding a binding agent to the wet dough to allow cohesion of the cellulosic fibers by gelation of the binder to form a gelled dough; and converting the gelled paste to form the absorbent cellulosic particles.

According to an optional aspect of the process, the method may include a pretreatment step of the paper sludge before mixing into a wet paste.

According to another optional aspect of the method, the pre-treatment step may include an adjustment of a paper sludge moisture, a purification of the paper sludge with a disinfecting agent or a combination thereof.

According to another optional aspect of the process, the step of converting the gelled paste may include a step of extruding the gelled paste into absorbent extrudates and a step of reducing the size of the absorbent extrudates to form the absorbent cellulosic particles. Optionally, the size reduction step is a grinding step.

According to another optional aspect of the process, the step of converting the gelled paste may include a step of scaling, granulating, pelletizing, pelletizing or compaction to form the cellulosic absorbent particles.

According to another optional aspect of the process, the method may include, after the conversion step, a step of drying the absorbent cellulosic particles to obtain cellulosic particles having a moisture of between 4% and 12%.

According to another optional aspect of the process, the process may include, after the conversion step, a step of sieving the absorbent cellulosic particles in a defined particle size distribution

According to another optional aspect of the process, the method may include, after the conversion step, a step of adding an agglomerating mixture to the cellulosic particles in order to coat an outer surface so that the cellulosic particles agglomerate on the surface. contact of a material to absorb.

According to another optional aspect of the process, the step of adding an agglomerating mixture may include at least:

depositing a first layer comprising at least one surfactant on the outer surface of the matrix structure; and

depositing a second layer comprising at least one agglomerating agent on the first layer.

According to another optional aspect of the process, the at least one surfactant may be added in liquid form and the at least one agglomerating agent is added in powder form.

According to another optional aspect of the method, a third layer comprising at least one surfactant may be deposited on the second layer. According to another optional aspect of the method, the step of adding an agglomerating mixture may include the deposition of a layer comprising an odor control agent on a previous layer comprising the at least one surfactant or the at least one agent controller.

According to another optional aspect of the method, the odor control agent may be added in liquid form or in powder form.

According to another optional aspect of the process, the steps of mixing into a wet paste and adding a binder to form a gelled paste can be done simultaneously. According to another optional aspect of the process, the binder can be added to the wet dough in the form of a dry powder, a colloidal agent, an emulsion or a gel.

According to another optional aspect of the process, the step of mixing into a wet paste can be carried out in a high shear mixer.

According to another optional aspect of the process, the wet pulp may have a water content of between 10 and 65% by weight relative to the total weight of the wet pulp. Optionally, the water content of the wet pulp can be between 10 and 30% by weight.

According to another optional aspect of the process, the wet pulp may have an ash content of less than 25% by weight relative to the total weight of the wet pulp. Optionally, the ash content of the wet pulp may be between 15 and 20% by weight.

According to another aspect of the present invention, it is proposed a use of cellulosic particles as defined above or produced according to the method as defined above, to be contacted and absorb animal urine in a tank litter.

According to one aspect of the invention, there is provided an absorbent comprising cellulosic particles capable of being contacted with a material, the absorbent cellulosic particles comprising: a binder agent gelled to form a matrix structure; and

It is understood that each of the litter aspects mentioned in this application can be adapted to each of the absorbent aspects mentioned in this application.

BRIEF DESCRIPTION OF THE FIGURES

The various features of the invention and other optional aspects are illustrated through the following figures.

Figure 1 is a photograph of granules of cellulosic absorbent of large size obtained by granulation (prior art).

Figure 2 is a schematic of an absorbent cellulosic particle according to an optional aspect of the present invention.

Figure 3 is a sectional view of Figure 2 along the line III.

Figure 4 is a photograph of the de-inking paper sludge according to an optional aspect of the present invention.

Figure 5 is a photograph of brown sludge according to an optional aspect of the present invention. Figure 6 is a schematic of a cellulosic particle and its cross-section according to an optional aspect of the present invention.

Figure 7 is a view of half of Figure 5.

Figure 8 is a block diagram of the process for producing the absorbent particles according to an optional aspect of the present invention.

Figure 9 is a block diagram relating to the addition of a binder in the process illustrated in Figure 8 according to an optional aspect of the present invention. Fig. 10 is a block diagram relating to the addition of a binder in the process illustrated in Fig. 8 according to another optional aspect of the present invention.

Fig. 11 is a block diagram relating to the addition of a binder in the process illustrated in Fig. 8 according to another optional aspect of the present invention.

Fig. 12 is a block diagram of a step of the method illustrated in Fig. 8 according to another optional aspect of the present invention.

Figure 13 is a block diagram of a sequence of steps of the method illustrated in Figure 8 according to another optional aspect of the present invention.

Figure 14 is a schematic of a twin-screw extruder according to an optional aspect of the present invention.

Fig. 15 is a graph showing ammonia evolution of cellulosic particles as a function of time according to an optional aspect of the present invention.

Although the invention is described with respect to the aspects illustrated by the above-mentioned figures, it is of course understood that the scope of the invention is not limited to these examples alone. On the contrary, all alternatives, modifications and possible equivalents are potentially considered, in light of the description and the claims that follow.

DETAILED DESCRIPTION OF THE INVENTION

The absorbent relating to the present invention includes absorbent cellulosic particles whose structure, composition and particle size distribution are adequate to ensure the effective absorption of an absorbent material brought into contact with the particles. Cellulosic absorbent particles also limit the release of odors potentially associated with the material to be absorbed and its degradation.

The absorbent relative to the present invention can be used as litter for the absorption of animal excretions. Cellulosic particles can absorb excretions from farm animals or smaller pets, such as cats. The absorbent is however not limited to this use and can be used to absorb chemicals or a liquid spill from an industrial activity, such as the petroleum industry. The absorbent may also be packaged so as to be in contact with food (meat, poultry, fish) put in trays for example, or conditioned to be contained in mattresses or other personal hygiene equipment.

Absorbent cellulosic particles include a binder and cellulosic fibers. The binder is gelled to form a matrix structure in which the cellulosic fibers are dispensed.

The cellulosic fibers distributed within the matrix structure of the particles may be derived from paper sludge, paper or a combination thereof. The use of paper sludges as a source of cellulosic fibers makes it possible to valorize these sludges and reduce the impact of their disposal on the environment. Paper sludge includes:

Gray sludge or de-inking sludge (Figure 4) is derived from paper recycling processes. These gray muds have a humidity ranging between 45 and 75%, an ash level varying between 45 and 65% and a pH ranging from 7 to 9.

Brown sludge (Figure 5) is sludge from processes related to cardboard. These brown sludges have a humidity ranging between 50 and 75%, a level of ash ranging between 2 and 30% and a pH ranging between 7 and 9. Recycled paper and paper have a moisture content of between 2 and 10%. and a color ranging from white to gray or brown.

As regards the cellulosic material, the length of the cellulosic fibers varies according to their origin. In the case of fibers from paper, fibers that are contained in good quality virgin paper are longer than those contained in newsprint. The latter are themselves longer than the cellulosic fibers contained in the recycled paper or in the paper sludge, such as de-inking sludge.

According to an optional aspect, the cellulosic particles contain cellulosic fibers from de-inking and paper sludge. Knowing that paper sludge contains a relatively low level of cellulosic fibers of great Thus, the paper sludge can be mixed with paper to obtain a base paste for making cellulosic particles containing cellulosic fibers of various lengths. The cellulosic fibers contained in the paper sludge have a length of between 0.1 and 10 mm and the cellulosic fibers contained in the paper have a length of between 1 and 3.5 mm. The low level of insoluble matter (also known as ashes) facilitates the incineration, biodegradability and composting of cellulosic particles after their use phase. The ash content of the particles may be between 10 and 30%, optionally 25%. Unlike cellulosic fibers from wood, cellulosic fibers in paper sludge are softened (due to the absence of lignin) and flattened. These characteristics make them fibers better suited to the manufacture of cellulosic particles. The use of cellulosic fibers from paper and / or paper sludge also makes it possible to obtain absorbent cellulosic particles with an average density of between 10 and 40 lbs / ft ³ , suitable for use in bedding, for example.

As illustrated in FIGS. 2 and 3, the cellulosic absorbent particles 2 comprise cellulosic fibers 4 which can be uniformly distributed within the gelled binding agent, which thus forms the matrix structure 6 holding the cellulosic fibers together.

According to an optional aspect, the binder may include a component derived from an organic or inorganic colloid.

According to an optional aspect, the binding agent may include guar gum, galactomannan gum, xanthan gum, methylcellulose, hydroxypropyl methylcellulose, carboxymethylcellulose, starch such as corn starch, lime wheat starch, cassava starch, potato starch and a combination thereof. The binder may include a super absorbent selected from polyacrylates, polyvinyl alcohol, pregelatinized wheat starch, pregelatinized corn starch, and a combination thereof. The superabsorbent binder may also be mixed with one or more other binding agents. Pre-gelatinization makes it possible, among other things, to perform the gelation of the binding agent, without the need to heat, simply by contact with the moisture of the paper sludge.

According to an optional aspect, the binder may include a clay such as montmorillonite, calcium bentonite, sodium bentonite, attapulgite, sepiolite or any combination thereof. The clay makes it possible to increase the density of the cellulosic particles, thus reducing the dispersion of these particles out of the container in which they are arranged. For example, when cellulosic particles are used as litter for cats, the clay contained in the particles makes them more dense and prevents them from being dragged by the cat out of the litter by clinging in the hairs of it. This may therefore be an advantage during the use phase of cellulosic particles in bedding, for example. In general, any binding agent making it possible to offer a dispersion-limiting particle density would preferably be used to constitute the matrix structure of the cellulosic particles.

According to an optional aspect, the cellulosic particles may include a plurality of layers deposited from the outer surface of the matrix structure, each layer conferring a particular property on the cellulosic particle, such as agglomerating power, odor control or amplification. absorption.

According to an optional aspect, the cellulosic particles 2 may include an agglomerating mixture 10 deposited on an outer surface 8 of the matrix structure 6, as shown in FIGS. 6 and 7. The absorbent cellulosic particles 2 may then also be clumping. The agglomerating mixture may include at least one surfactant and at least one agglomerating agent. The cellulosic particles may include a first layer 12 deposited on the outer surface 8 of the matrix structure 6 and comprising the at least one surfactant. This first layer 12 of surfactant can be used to wet the outer surface 8 of the matrix structure 6 and make it adherent to a second layer 14 comprising the at least one binding agent, deposited on the first layer 12.

According to an optional aspect, the agglomerating mixture may include at least one agglomerating agent which may include guar gum, xanthan gum, carboxymethylcellulose, polyethylene oxide, analogs thereof, or mixtures thereof.

The order of deposition of the surfactant clumping agent layers is not limited to that shown in Figures 6 and 7, and may include any combination that renders the particles clumping. In general, the cellulosic particles may include an intermediate layer comprising at least one agglomerating agent.

According to an optional aspect, the second layer of the particle comprising the at least one agglomerating agent may consist of a succession of a plurality of sub-layers, each sub-layer comprising an agglomerating agent. Alternatively, the second layer may include a mixture of agglomerating agents.

According to an optional aspect, still with reference to Figures 6 and 7, the cellulosic particles 2 may include a third layer 16 comprising at least one surfactant. The at least one surfactant of the first layer 12 may be the same or different from the at least one surfactant of the third layer 16. Each of the first 12 and third layers 16 may include one or more surfactants. The surfactant mixture of the first layer 12 may be the same as or different from the surfactant mixture of the third layer 16.

According to an optional aspect, the at least one surfactant may be ionic or nonionic. The at least one ionic surfactant may include sodium lauryl sulphate (LSS), polyethylene glycol p- (1,1,3,3-tetramethylbutyl) -phenyl ether, analogs thereof, and mixtures thereof. The at least one nonionic surfactant may include primary alcohols, ethyl phenoxy poly ethoxy ethanol, analogs thereof, and mixtures thereof.

The at least one surfactant acts as a wetting agent and improves the speed of absorption of the cellulosic particles having at least one layer comprising at least one surfactant as defined above. In addition, knowing that the material is then absorbed more quickly by the particles, odors that may result from the material to be absorbed are also reduced.

For example, when using cellulosic particles in bedding, the stagnation of a liquid such as urine is undesirable because it gives the possibility to the urine to remain in contact with the air for a time sufficient to initiate and accelerate the process of releasing two molecules of ammonia by urease attack on urea according to the following equation.

Urea + H ₂ O 2 NH ₃ + C0 ₂ (under the action of the enzyme urease)

In an optional aspect, to enhance control of potential odors, the cellulosic particles may include a layer comprising an odor control agent. This odor control agent layer may optionally be deposited on a layer comprising the at least one surfactant. Alternatively, the layer comprising the odor control agent may precede a final layer comprising the at least one surfactant, thus ensuring good adhesion of the odor control agent to the particle.

According to an optional aspect, the odor control agent may include a urease inhibiting agent. This is particularly indicated when cellulosic particles are used to absorb excreta in bedding for example. The urease inhibiting agent may include N (n-butyl) thiophosphoric triamide (nBTPT), cyclohexyl thiophosphoric triamide (CHTPT), N- (N-butyl) phosphoric triamide (NBPT), cyclohexyl phosphoric triamide (CHPT) ), N-aliphatic triamide, N, N-aliphatic phosphoric triamide, phosphorotriamides, 4-aminophenyl sulphonylamino phenylphosphorodiamidates, N- (diaminophosphinyl) arylcarboxamines and a combination thereof. The urease inhibitor agent may also be polysulfide, thiosulphate or any other similar agent, such as ferric sulfate and ricinoleates.

According to an optional aspect, the odor control agent may include boric acid, borax formulations or a combination thereof.

For example, the matrix structure of the cellulosic particles may be covered with an agglomerating mixture comprising at least one surfactant, at least one agglomerating agent and a urease inhibiting agent in the form of layers according to Table 1 below: Table 1

Succession of layers on the

matrix structure of the particle layer 1: 1% nonionic surfactant layer 2: 2% agent agglomerating layer 3: 2% nonionic surfactant layer 4: 2% agent agglomerating layer 5: 0.023% inhibiting agent

%: Percentage by weight relative to the total dry weight of the cellulosic particle.

Again according to FIGS. 2 and 3, the cellulosic fibers 4 can be uniformly distributed within the matrix structure 6 and generally be aligned with one another along an axis of the matrix structure 6.

This alignment makes it possible to obtain a matrix structure having a substantially smooth outer surface where the number of protrusions is reduced or zero. The matrix structure thus has an enlarged inter-particle contact surface that improves the contact between the absorbent particles, thus improving the absorption capacity of the particles. The presence of inter-particle voids through which the material to be absorbed can flow is also reduced as a result. When the matrix structure of the absorbent cellulosic particles is covered with the agglomerating mixture as defined above, the alignment of the cellulosic fibers also improves the ability of the particles to agglomerate together to form a clump. In addition, the absence or limitation of protrusions makes it possible to deposit the agglomerating mixture uniformly on the outer surface of the matrix structure of the particle. The contact surface being devoid of protrusions, the cellulosic particles agglomerate together efficiently when wet with a material to be absorbed.

Clump means any aggregate of clumping cellulosic particles formed as a result of agglomeration of the particles when they are brought into contact with the material to be absorbed. Clod force is defined as the ability of the clod to resist crumbling after a five second vibration time.

In an optional aspect, the cellulosic absorbent is in the form of cellulosic particles having a particle size distribution imparting to the absorbent desirable absorbent and clumping properties. Preferably, at least 90% of the particles are of a size to pass through a sieve of between 4 and 60 mesh and at most 10% of the remaining particles pass through a 100 mesh sieve. Optionally, at least 99% of the particles are sized to pass through a sieve of 8 to 60 mesh and at most 1% of the remaining particles pass through a 100 mesh screen. For example, the particle size distribution of the cellulosic particles may be as indicated in the following Table 2:

Table 2: Particle Size Distribution of Cellulosic Particles

The fineness of the particles is an important physical property involved in the absorbent capacity and agglomeration capacity of the cellulosic particles when they are brought into contact with an absorbable material. Fine particles are preferred because they provide a greater contact area between the agglomerating mixture and the material to be absorbed relative to larger particles. A good agglomeration makes it possible to control the rate of absorption and to prevent any unabsorbed liquid from flowing, for example, into the bottom of the container containing the cellulosic particles. In the case of use in litter for example, the agglomeration of the particles prevents any liquid excretion from flowing to the bottom of the litter box; the liquid excretion passes only a few centimeters thick litter, thus preventing the development of odors stagnant liquid at the bottom of the tray. The clumps formed can then be easily removed by a user using a suitable shovel, for example.

According to an optional aspect, the absorbent cellulosic particles may have a concentration by weight of cellulosic fibers of at least 50 to 75% and a concentration by weight of the binding agent of not more than 25%. The concentration by weight of cellulosic fibers can also be 80% and the concentration by weight of binding agent of 20%.

According to another optional aspect, the agglomerating absorbent cellulosic particles may have a concentration of at least 74% by weight of cellulosic fibers, a concentration by weight of the binding agent of at most 19% and a concentration by weight of agglomerating mixture. not more than 7%.

For example, the absorbent cellulosic particles and the agglomerating absorbent cellulosic particles may have a composition as defined in the following Table 3:

Table 3: Composition of cellulosic particles

^* The 100% complement is done by the ash content. According to an optional aspect, for example when used in litter or for a product including the cellulosic particles as defined above, it is possible to add to the cellulose particles indicator particles that can change color when they come into contact with each other. contact with excretions. Indicator particles may include a color former and an oxidizing agent. This makes it possible, for example, to detect urinary diseases in animals during litter use. Optionally, the litter may include at least 99% cellulosic particles and at most 1% indicator particles. Optionally, the litter may include from 0.04% to 0.2% indicator particles. The present invention also relates to a process for producing absorbent cellulosic particles including a binder and cellulosic fibers from paper sludge, paper or a combination thereof. The method includes the following steps:

mixing sludge and / or paper into a wet paste;

The paper sludge has the advantage of having a high humidity for forming, during the mixing step, a wet paste having a consistency and a water content adequate to receive the binding agent. Optionally, the method may include a step of adjusting the moisture of the dough. This can be done by adding water or drying the sludge according to the desired humidity. Optionally, paper may be added to the sludge mixture to incorporate cellulosic fibers of longer length than the sludge fibers into the wet pulp. The paper can also reduce the moisture or ash content of the dough. The paper does not need to be moistened beforehand and takes advantage of the water content of the wet sludge with which it is mixed. The moisture of the dough is also a parameter influencing the efficiency of the mixing step. Optionally, the wet paste may have 10 and 50% by weight of water relative to the total weight of the dough. In addition, it may have an ash content of less than 25% by weight relative to the total weight of the dough, preferably between 15% and 20% by weight relative to the total weight of the dough. Again optionally, the mixing step can be carried out in a high shear mixer. It is understood, however, that the present process is not limited to the use of a high shear mixer and includes the use of a kneader or rotary mixer for example.

Knowing that paper sludges, such as deinking sludge, may contain microorganisms, a pre-treatment step may be included in the above-mentioned process in order to sanitize the sludge before the mixing step. This pre-treatment step may include the addition of a sanitizing agent to the paper sludge. The disinfecting agent can be added in the form of a powder or even within the paper sludge. Optionally, the pre-treatment step may include heat treatment in the presence of hydrogen peroxide (H ₂ O ₂ ), sodium bicarbonate (NaHCO ₃ ), sodium hypochlorite (NaOCI), chloramine-T and / or essential oils such as thymol. Heat treatment in the presence of hydrogen peroxide is preferred.

According to an optional aspect, the binder may be added to the wet pulp as a dry powder, a colloidal agent, an emulsion or a gel to form a gelled paste. As previously described, the gelation of the binder acts to bind the various cellulosic fibers together, including short and long fibers, forming a gel matrix. Optionally, it may be desirable to add water to facilitate gelation of the binder. It is understood that the process is not limited to subsequent binder addition to the sludge and / or paper mixing step into a wet paste. The addition of the binding agent can be carried out simultaneously with the mixing step within the mixer or, simultaneously, with the step of converting the gelled paste into absorbent cellulosic particles.

Figures 9, 10 and 11 illustrate possible options for the step of adding the binding agent to the wet dough. According to Figure 9, the binder can be added from the first mixing step within the mixer itself. According to FIG. 10, the binding agent can also be added to the wet paste at the mixer outlet and before carrying out the conversion step, for example in an extruder. According to Figure 11, the binder may be added during the conversion step. For example, during an extrusion step, the binder can be added through injection ports of the extruder. The binding agent can be injected in gelled form (off-extruder gelling) or in order to to gel in the extruder (internal gelation). It is also possible to add each of the raw materials in the extruder so that they are mixed in a section upstream of the extruder.

According to an optional aspect, the step of converting the gelled paste into absorbent cellulosic particles may include an extrusion step, a scaling step, a granulation step, a pelletizing step, a pelletising step or a compaction step. to form the absorbent cellulosic particles from the gelled paste. The conversion step may optionally include a subsequent size reduction step, such as a grinding step, when the apparatuses used for the conversion do not make it possible to obtain cellulosic particles whose particle size is as defined above.

For example, the use of an extruder equipped with rotary knives at the die outlet, as illustrated in FIG. 12, makes it possible to convert the gelled paste into absorbent extrudates and at the same time to reduce the size of the absorbent extrudates to form the particles. absorbent cellulosic. In this case, to achieve the desired particle size distribution, at least two rotary knife extruders can be used in parallel and / or the cost rotation speed is changed for a single extruder. Each extruder being set to a different die size, to obtain particles of different size for each die and form the desired particle size distribution by collecting the types of particles.

Optionally, the extrusion step can be done in a conventional twin-screw or twin-screw extruder. Depending on the die size of the extruder, it is possible that the gelled paste is converted into absorbent extrudates whose size is not suitable for use as absorbent cellulosic particles according to the present invention. A subsequent size reduction step, such as a grinding step, would then be desirable to obtain cellulosic particles of adequate size. A twin-screw extruder, as shown in Figure 14, may be used during the conversion step. It includes two sets of mixing elements to uniformly gel the dough. The extruder is divided into sections (1 to 1 1) of different lengths, in which the two screws may have a different screw pitch. The ratios of the screw pitches to the length of the section are indicative in Figure 14. The annotations KB45 and KB90 indicate the pitch angle of the screw. The port Injection A is intended for solids and allows the introduction of paper and / or paper sludge into the extruder. This port A also makes it possible to optionally introduce the binder in the form of a powder. The second injection port B and the third injection port C are intended for adding liquid. These ports B and C may therefore be optionally used to introduce any liquid, such as water or the binding agent in the form of an emulsion, gel or solution.

Optionally, the die size of the extruder may be adapted to obtain cellulosic particles of desired size without resorting to a subsequent step of size reduction by grinding. According to an optional aspect, the conversion step is carried out at a temperature between 10 and 105 ° C. This temperature depends on the type of conversion carried out and the apparatus used, for example according to the extrusion, the cubage, the granulation, the pelletizing, the pelletization or the compaction. Cubage can be performed at room temperature while extrusion may require or produce heat. The temperature used during extrusion varies between 20 ° C and 105 ° C depending on the pressure, the shear force and the nature of the gelling agent. Optionally, the method may include a temperature control during the extrusion step, to ensure good gelation of the binder and to control the evaporation of the water contained in the wet paste. In contact with the water contained in the paste and, if appropriate, heat, the binding agent gels and forms a gel matrix. The cellulosic fibers are then bound by this gel matrix.

According to an optional aspect, the cellulosic particles resulting from the conversion step are of cylindrical shape. It is understood that the shape of the cellulosic particles is not limited to a cylindrical shape and includes the spherical, cubic, ovoid and other possible shapes depending on the apparatus used during the conversion step.

According to an optional aspect, the method may include a step of drying the cellulosic particles, subsequent to the conversion step. Optionally, in the case where the conversion step includes a size reduction step, such as grinding, the drying can be done before this size reduction step. It should be noted that in some cases, the drying can be done by evaporation during the extrusion step. According to an optional aspect, the method may include a step of sieving the cellulosic particles, subsequent to the conversion step. Sieving is a step that makes it possible to control the obtaining of cellulose particles according to the particle size distribution defined above, especially in Table 2. The sieving step includes a passage of the cellulosic particles through different sieves, such as a succession sieves> 4 mesh,> 10 mesh, <70 mesh and <100 mesh.

According to FIG. 13, the process includes a step of converting the gelled paste into extruded granules, a step of grinding into cellulosic particles and a sieving step in order to sort the cellulosic particles according to the desired particle size. According to an optional aspect, the method includes, after the conversion step, a step of adding an agglomerating mixture to the cellulosic particles so as to coat an external surface so that the cellulosic particles agglomerate in contact with a matter to absorb. The agglomerating mixture is ultimately added to the absorbent cellulosic particles in order to improve their absorption and to give them an agglomerating clump capacity. Agglomerating absorbent cellulosic particles are thus produced. The matrix structure gelled with the binding agent makes it possible to establish a cohesion between the cellulosic fibers and, as a result, the cellulosic particles can thus more easily agglomerate together in the presence of a strong liquid excretion for example. Optionally, the step of adding the agglomerating mixture may be carried out in a mixer, a kneader or a rotary mixer. As defined above, the agglomerating mixture may include at least one surfactant and at least one agglomerating agent, layered from the outer surface of the matrix structure. The surfactant is added first to wet the outer surface of the matrix structure, and to allow the agglomerating agent to adhere to the cellulosic particle.

Optionally, each of the constituents of the agglomerating mixture may be added to the outer surface of the cellulosic particles by spraying, spraying, atomizing, dispersing or any similar technique for uniformly distributing the agglomerating mixture on the outer surface of the cellulosic particles in the order chosen for layers. It is understood that the agglomerating mixture may include several surfactants and several agglomerating agents. These can be distributed on the surface of the particles successively in a precise order or simultaneously according to the desired layer arrangement.

According to an optional aspect, the step of adding the agglomerating mixture may include

depositing a first layer including at least one surfactant on the outer surface of the gelled matrix structure; and

depositing a second layer including at least one agglomerating agent on the first layer. According to an optional aspect, a third layer may be deposited on the second layer, the third layer including

at least one agglomerating agent, identical or different from that contained in the second layer;

at least one surfactant, identical to or different from that contained in the first layer; or

an odor control agent.

According to an optional aspect, the step of adding the agglomerating mixture can include the deposition of a final layer comprising at least one surfactant, making it possible to accelerate the absorption of any absorbable material within the cellulosic particle. According to an optional aspect of the invention, the odor control agent can be added simultaneously to the conversion step.

EXAMPLES

Experiments were carried out to evaluate in particular various parameters characterizing the absorption of the cellulosic particles according to the present invention. All the particles studied were used as bedding in a 16.5 cm deep tray.

Dosimetry, the calculation of the release of ammonia over time, was carried out by enclosing 350mL of the litter and a solution of 50g of water in a container. supplemented with 0.012 g of urease and 7.5 g of urea. The release of ammonia is determined through a tube inserted into the closed container. The density of the particles is evaluated on a standard volume of 324 mL of litter. The free swelling capacity (FSC) of the particles is calculated by submerging 0.5 g of particles in water for 1 minute. The particles are then dried for a given lapse of time and the amount of water retained is then calculated.

Example 1

Table 4: Dosimetry of the clumping cellulosic particles (including the agglomerating mixture) according to the composition of the wet paste

Figure 15 shows graphically the results of Table 4 above.

Table 4 and Figure 15 show that the particles being produced from the wet dough mixture comprising the most de-inking sludge (90%) and including the binding agent (maize starch) obtain the lowest dosimetry.

Example 2

Table 5 compares commercially available cellulosic particles (A, B, C and D) with cellulosic absorbent particles according to the present invention (E, from mixture I of Table 4). Table 5: Comparative Results of Existing Absorbent Bedding

Granulometry A B C D E

Characterization Thickness Thickness Thickness Thickness I Granules Kraft ^® Medium Granules Medium Average 90% more than 3 mm granules: 5.38 of 2.36 mm width and mm granules: granules:

80 mm - Length 4.2 mm 4.2 mm

long average - Length - Length

compressed granules: 12.6 average average

30min.

^* FSC: Free Swelling Capacity (free swelling index: Absorption capacity of particles when submerged in a liquid for a given time).

^** The water is at the bottom of the tank without being absorbed.

^*** The measuring devices used were not able to quantify the absorption capacity of the liquid because these particles had little or no agglomerating properties.

^**** Too scattered to be measured.

According to an optional aspect, the dosimetry after 48h may be less than 25 ppm and preferably less than 20 ppm. From the dosimetry results of Table 5, the cellulosic absorbent according to the present invention has a better odor absorption rate. Example 3

Table 6 summarizes the root strength, density and dosimetry results for absorbent and agglomerating cellulosic particles (including the optional binder blend of the present invention). The particles studied were produced from three mixtures (IV, V and VI) defined below.

Table 6: Physical Properties of Clumping Particles Produced from Paste Mixes IV, V and VI

Mixture IV: 5% sodium bentonite and 95% de-inking sludge;

Mixture V: 10% sodium bentonite and 90% de-inking sludge; and

Mixture VI: 20% sodium bentonite and 80% de-inking sludge.

Table 6 shows that the root force is generally the same regardless of the base mixture. This is explained by the fact that the process according to the present invention makes it possible to obtain clumping cellulosic particles devoid of protrusions and offering a large agglomeration surface whatever the composition of the basic gelled paste.

Table 6 also shows that an increase in the amount of clay (sodium bentonite as binding agent) makes it possible to increase the density of the agglomerating particles and thus reduce the volatility and the scattering thereof.

Table 6 also shows that an increase in the amount of fiber (by increasing the percentage of sludge in the pulp) leads to a greater absorption capacity.

Example 4

Table 7 below lists various realized Blend recipes and Table 7 lists the moisture parameters of the slurry and the liquid absorption of the particles without the agglomerating mixture. Table 7: Composition of different wet paste mixtures

It is found that it is from the "blend 6" containing a low moisture content (about 18%) and which consists of the three ingredients paper, mud and binder, we obtain cellulosic particles with the best capacity of absorption of the liquid. In addition, for a similar moisture content, there is an improvement in the absorption of 30% between the blend 4 and the blend 6.

It is understood that each of the above mentioned cellulosic particle aspects can be combined with each of the above mentioned aspects of the particle manufacturing process, except where there is obvious incompatibility. For example, in the process, the step of adding the agglomerating mixture may be adapted to achieve all the described layer variants with respect to the cellulosic particles.

The absorbent (combination of paper sludge, paper and binder) can be used as a substrate in a litter as described in the following patent applications: CA 2,688,496, US 61 / 329,150 and PCT / CA2011 / 000502 and all corresponding requests. These requests are incorporated in this document by reference.

Claims

1. A litter comprising absorbent cellulosic particles capable of being contacted with a material, the cellulosic absorbent particles comprising: a gelled binding agent to form a matrix structure; and a plurality of cellulosic fibers distributed within the matrix structure; the cellulosic fibers being derived from paper sludge, paper or a combination thereof.

The litter of claim 1, wherein the paper sludge comprises de-inking sludge.

3. The litter of claim 2, wherein at least 50% by weight of the cellulosic fibers are from deinking sludge.

4. The litter according to claim 2 or 3, wherein all of the cellulosic fibers are from de-inking sludge.

The litter of claim 2 or 3, wherein at least a portion of the cellulosic fibers are derived from recycled paper.

The litter of any one of claims 1 to 5, wherein the cellulosic fibers are substantially uniformly distributed within the matrix structure.

The litter of claim 6, wherein the cellulosic fibers are substantially aligned along an axis of the matrix structure.

The litter of claim 6 or 7, wherein the cellulosic fibers are sufficiently aligned to reduce or eliminate the presence of protrusions on a contact surface of the matrix structure.

9. The litter according to any one of claims 1 to 8, wherein the cellulosic fibers have a length of between 0.1 and 10 mm.

10. The litter according to any one of claims 1 to 9, wherein 5 to 50% of the cellulosic fibers have a length of between 0.1 and 3.5 mm.

1. The litter of any one of claims 1 to 10, wherein the binder comprises a component which is derived from an organic colloid.

The litter of any one of claims 1 to 11, wherein the binder comprises a component which is derived from an inorganic colloid.

13. The litter according to any one of claims 1 to 12, wherein the binding agent comprises guar gum, galactomannan gum, xanthan gum, methylcellulose, hydroxypropyl methylcellulose, carboxymethylcellulose, corn starch, wheat starch, cassava starch, potato starch, lignin, lignin derivatives or a combination thereof.

The litter of any of claims 1 to 13, wherein the binder comprises a superabsorbent comprising polyvinyl alcohol, a polyacrylate, pre-gelatinized wheat starch, pre corn starch gelatinized or a combination thereof.

The litter of claim 14, wherein the binder is the superabsorbent.

The litter of any one of claims 1 to 14, wherein the binder comprises a clay.

The litter of claim 16, wherein the cellulosic particles comprise at most 25% by weight of clay based on the total weight of the cellulosic particles.

18. The litter of claim 16 or 17, wherein the clay comprises calcium bentonite, sodium bentonite or a combination thereof.

Litter as claimed in any one of claims 1 to 18, wherein the cellulosic particles have a concentration by weight of cellulosic fibers. between 50% and 75%, and a concentration by weight of the binding agent of at most 20%.

The litter of any one of claims 1 to 19, wherein at least a portion of the cellulosic absorbent particles comprise an agglomerating mixture distributed on an outer surface of the matrix structure so that the cellulosic particles can agglomerate upon contact with the matter.

21. The litter of claim 20, wherein the agglomerating mixture comprises at least one surfactant and at least one agglomerating agent.

The litter of claim 21, wherein the cellulosic particles comprise a first layer comprising the at least one surfactant which is deposited on the outer surface of the matrix structure, and a second layer comprising the at least one agglomerating agent which is deposited on the first layer.

The litter of claim 21, wherein the cellulosic particles comprise a plurality of layers deposited successively from the outer surface of the matrix structure, each layer comprising the at least one surfactant or the at least one agglomerating agent.

The litter of claim 21, wherein the at least one surfactant comprises a first surfactant and a second surfactant, and the cellulosic particles comprise:

a first layer deposited on the outer surface of the matrix structure, the first layer comprising the first surfactant; a second layer deposited on the first layer, the second layer comprising the at least one agglomerating agent; and

25. The litter according to any one of claims 21 to 24, wherein the at least one surfactant comprises an ionic surfactant selected from the group consisting of sodium lauryl sulfate, polyethylene glycol p- (1, 1, 3,3- tetramethylbutyl) -phenyl ether, analogs thereof, and mixtures thereof.

The litter of any one of claims 21 to 25, wherein the at least one surfactant comprises a nonionic surfactant selected from the group consisting of primary alcohols, ethyl phenoxy poly ethoxy ethanol, analogs thereof. ci and mixtures thereof.

27. The litter according to any one of claims 21 to 26, wherein the at least one agglomerating agent comprises guar gum, xanthan gum, carboxymethylcellulose, polyethylene oxide, the analogs thereof or the mixtures thereof.

28. The litter according to any one of claims 1 to 27, comprising an odor control agent reducing or eliminating the release of odors that may result from the material.

The litter of claim 28, wherein the cellulosic particles comprise a layer comprising the odor control agent.

30. The litter according to any one of claims 21 to 29, wherein the cellulosic particles comprise a penultimate layer comprising the odor control agent and a final layer comprising the at least one surfactant.

The litter of any one of claims 28 to 30, wherein the odor control agent is a urease inhibitory agent.

The litter of claim 31, wherein the urease inhibiting agent is selected from the group consisting of N (n-butyl) thiophosphoric triamide, cyclohexyl thiophosphoric triamide, N- (N-butyl) phosphoric triamide, cyclohexyl phosphoric triamide, N-aliphatic triamide and N, N-aliphatic phosphoric triamide, phosphorotriamides, 4-aminophenyl sulphonylamino phenyl phosphorodiamidates, N- (diaminophosphinyl) arylcarboxamines, polysulfides, ferric sulphate, thiosulphates, ricinoleates, mixtures thereof and analogs thereof.

33. The litter according to any one of claims 1 to 32, wherein the cellulosic particles have a particle size of between 4 and 100 mesh.

34. The litter according to claim 33, wherein the cellulosic particles have a particle size distribution in which at least 90% of the cellulosic particles have a particle size of between 4 and 60 mesh, and at most 10% of the cellulosic particles have a particle size of less than 100 mesh.

35. The litter according to claim 33 or 34, wherein the cellulosic particles have a particle size distribution in which at least 95% of the cellulosic particles have a particle size of between 8 and 60 mesh, at most 5%, with a particle size of less than 70. mesh and at most 2% of the cellulosic particles has a particle size less than 100 mesh.

36. The litter of any one of claims 1 to 35, wherein the cellulosic particles have a density of between 15 and 40 lbs / ft ³ .

37. The litter according to any one of claims 20 to 36, wherein the cellulosic particles have a concentration by weight of cellulosic fibers of between 45 and 70%, a concentration by weight of the binding agent of at most 19%. and a concentration by weight of agglomerating mixture of at most 7%.

38. The litter according to any one of claims 20 to 37, wherein the cellulosic particles, when brought into contact with urine, have a release of ammonia between 0 and 25 ppm after 48 hours.

39. The litter of any one of claims 1 to 38, wherein the cellulosic particles have a substantially cylindrical shape.

40. The litter according to any one of claims 1 to 39, comprising additional indicator particles that can change color when in contact with excretions, the indicator particles comprising a color former and an oxidizing agent.

41. The litter according to claim 40, comprising at least 99% of cellulosic particles and at most 1% of indicator particles.

42. The litter of claim 40 or 41 comprising 0.04% to 0.2% indicator particles.

A method of making a litter comprising absorbent cellulosic particles, the method comprising the steps of: mixing paper sludge and / or paper to form a wet paste comprising cellulosic fibers; adding a binding agent to the wet dough to allow cohesion of the cellulosic fibers by gelation of the binder to form a gelled dough; and converting the gelled paste to form the absorbent cellulosic particles.

44. The method of claim 43 comprising a step of pre-treating the paper sludge before mixing into a wet paste.

45. The method of claim 44, wherein the pre-treatment step comprises adjusting a sludge moisture, sanitizing the sludge with a disinfectant or a combination thereof.

46. The process according to any one of claims 43 to 45, wherein the step of converting the gelled paste comprises a step of extruding the gelled paste into absorbent extrudates and a step of reducing the size of the absorbent extrudates for form the absorbent cellulosic particles.

47. The method of claim 46, wherein the step of reducing size is a grinding step.

48. The process of any one of claims 43 to 45, wherein the step of converting the gelled paste comprises a step of scaling, granulating, pelletizing, pelletizing or compaction to form the absorbent cellulosic particles.

49. The process according to any one of claims 43 to 48, comprising, after the conversion step, a step of drying the absorbent cellulosic particles to obtain cellulosic particles having a moisture of between 4% and 12%.

50. The process according to any one of claims 43 to 48, comprising, after the conversion step, a step of sieving the absorbent cellulosic particles in a defined particle size distribution.

51. The process according to any one of claims 43 to 50, comprising, after the conversion step, a step of adding an agglomerating mixture to the cellulosic particles in order to coat an external surface so that the cellulosic particles agglomerate in contact with a material to be absorbed.

52. The method of claim 51, wherein the step of adding an agglomerating mixture comprises at least the deposition of a first layer comprising at least one surfactant on the outer surface of the matrix structure; and depositing a second layer comprising at least one agglomerating agent on the first layer.

53. The process according to claim 52, wherein the at least one surfactant is added in liquid form and the at least one agglomerating agent is added in powder form.

54. The method of claim 52 or 53, wherein a third layer comprising at least one surfactant is deposited on the second layer.

The method of any one of claims 51 to 54, wherein the step of adding an agglomerating mixture comprises depositing a layer comprising an odor control agent on a previous layer comprising the at least one a surfactant or the at least one controller agent.

56. The method of claim 55, wherein the odor control agent is added in liquid form or in powder form.

57. The process according to any of claims 43 to 56, wherein the steps of mixing into a wet paste and adding a binder to form a gelled paste are done simultaneously.

58. The process according to any one of claims 43 to 57, wherein the binding agent is added to the wet pulp in the form of a dry powder, a colloidal agent, an emulsion or a gel .

The process of any one of claims 43 to 58, wherein the step of mixing into a wet paste is performed in a high shear mixer.

60. The process according to any one of claims 43 to 59, wherein the wet pulp has a water content of between 10 and 65% by weight relative to the total weight of the wet pulp.

61. The process according to claim 60, wherein the water content of the wet pulp is between 10 and 30% by weight.

62. The process according to any one of claims 43 to 61, wherein the wet pulp has an ash content of less than 25% by weight relative to the total weight of the wet pulp.

63. The process according to claim 62, wherein the ash content of the wet pulp is between 15 and 20% by weight.

64. The use of the cellulosic particles as defined in any one of claims 1 to 42 or produced according to the process as defined in any one of claims 43 to 63, for contacting and absorbing animal urine in a container of litter.