RU2198729C2 - Method of manufacturing absorbing material (options), absorbing material (options), and a liquid absorption method - Google Patents

Abstract

FIELD: organic sorbents. SUBSTANCE: manufacture procedure includes preparing pulp from undestroyed and uncut secondary fiber with moisture content above about 40%, granulating this pulp to form wet granules, and drying the latter. Material particularly suits as absorbent for liquid trade wastes and/or as litter. EFFECT: simplified manufacture procedure. 22 cl, 13 ex

Description

FIELD OF THE INVENTION
The invention relates to a method for producing absorbent materials (options), an absorbent material (options) and a method for absorbing a liquid. More specifically, the present invention relates to methods for producing absorbent materials from pulp of a secondary fiber.

BACKGROUND OF THE INVENTION
Absorbent materials, in particular granular absorbent materials, are used for a variety of industrial and domestic purposes. Typical applications include the absorption of liquids, such as water, oil, grease and solvents, spilled on floors and other surfaces, as well as bedding for animals, such as bedding for cats.

 Typically, conventional granular liquid absorbents contain organic or inorganic absorbent materials that are found in nature, such as clay, sand, wood shavings, sawdust, peanut shells, rice husks and shredded paper, cardboard and newsprint. Animal bedding contains a special class of granular liquid absorbents and is used to collect animal excreta in households where pets are kept, especially cats. Conventional animal litter typically contains inert materials with a large surface area, such as clay, bentonites and cellulose. To improve or mask odors, fragrance or odor control agents may be added to some of these materials.

Conventional absorbent materials, including absorbents for industrial liquid waste and animal litter, have the disadvantage that they typically have low absorption capacity and suffer from dust and disposal problems. Typical known absorbent materials can absorb liquid in an amount equal to or less than their own weight. Accordingly, these materials are quickly saturated and must be frequently discarded and replaced. This increases the costs associated with the use of absorbents for liquid industrial waste and bedding for animals. Speaking specifically about animal bedding, there are also problems with disposal, since saturated bedding often sticks to bedding trays and troughs. Conventional absorbents also have high bulk densities, typically from about 36 to about 50 lb / ft ³ (0.576-0.800 g / cm ³ ), which creates consumer handling problems. In addition, there is a tendency for ordinary litter to adhere to the paws of pets, with the result that the litter is scattered out of the box with it. This creates problems in the household. In addition, inorganic absorbents, such as clay absorbents, are abrasive and can cause damage to the flooring nearby.

 There is an increasing need for methods of disposing of pulp from paper mills. In a typical waste paper recycling plant, 100 tons of waste paper by dry weight can be processed into about 65-80 tons of recycled (reuse) fiber by dry weight. The remaining 20-35 tons of waste paper are unsuitable and form part of the sludge generated at the waste paper processing plant. This unsuitable slurry typically contains from about 50 to about 70 percent water. Thus, from 100 tons of waste paper by dry weight, it is possible to obtain from about 70 to about 120 tons of sludge requiring disposal, by wet weight.

 Common sludge disposal methods include landfill, soil spreading, composting and incineration. Landfills and landfills are depleted at an alarming rate, and the formation of new sites is difficult in terms of protecting the environment. Composting and burning sludge also raises environmental concerns. Some innovative sludge disposal techniques include sludge processing into fuel pellets or into lightweight construction aggregates, pyrolysis, gasification and cementation. However, these techniques usually require the use of sophisticated methods and expensive equipment.

 The introduction of sludge fiber into animal litter has also been reported. For example, Lewe et al. US Pat. No. 4,721,059 describes animal fillers made from waste materials that are obtained during paper production. Methods for the manufacture of animal fillers according to Lowe et al. Suffer from the disadvantages that they require breaking or grinding dehydrated fibers using a lump breaking device, reduction mill or grinder to a fiber length of 1 to 10 mm, with a fiber length of 1 to 1 being preferred. up to 4 mm. Breaking or grinding fibers to a specific length requires additional stages of production, and therefore increases production costs.

 Cortigene et al. US Pat. No. 4,203,388 describes an animal litter containing granular and dried waste from a secondary fiber factory. Methods for making animal bedding according to Cortigen et al. Suffer from the disadvantages that they require pulp dehydration to a water content of between about 32 and 40%. Dehydration of the pulp to a water content of 40% and below can be difficult. Moreover, in the methods described in the patent by Cortigene et al., It is required that the crust of the dehydrated pulp be cut into small pieces before granulation. Dehydration of the pulp to a water content of 40% or less and cutting the pulp peel into small pieces requires additional production steps and therefore increased production costs.

 Although methods have been developed for recycling pulp fibers into recycled paper products, these methods are not widely accepted due to the difficulty associated with quality control of recycled paper products.

 Accordingly, new and / or better absorbent materials are required, including absorbent materials for use as absorbents for industrial liquid waste and household absorbents such as animal bedding. In addition, new / or better ways of using or disposing of fiber pulp are required. The present invention relates to these, as well as other important objectives.

SUMMARY OF THE INVENTION
The present invention relates in part to methods for producing absorbent materials and to the absorbent materials themselves. One embodiment of the invention provides methods for producing an absorbent material, which comprise obtaining pulp of an undamaged and uncut secondary fiber having a moisture content of more than about 40%. The pulp is granulated to form wet granules, which are then dried.

 Another aspect of the present invention relates to methods for producing absorbent material, which include obtaining pulp of a secondary fiber having a moisture content of from more than about 50% to less than about 70%. The pulp is granulated to form wet granules, which are then dried.

 Another aspect of the present invention relates to an absorbent material, which is obtained by the method, including obtaining pulp intact and uncut secondary fiber having a moisture content of more than about 40%. The pulp is granulated to form wet granules, which are then dried.

 Another aspect of the present invention relates to absorbent material obtained from pulp of a secondary fiber. The absorbent material has a bulk density of less than about 36 lb / cc. ft (0.576 g / cc) and a liquid absorption capacity of at least about 1.1.

 Another aspect of the invention relates to methods for absorbing a liquid, which comprises contacting the liquid with an absorbent material. The absorbent material is obtained by a method including obtaining pulp of underexposed and uncut secondary fiber having a moisture content of more than about 40%. The pulp is granulated to form wet granules, which are then dried.

 Using embodiments of the present invention, very desirable and unexpected advantages are achieved. In this regard, the absorbent materials of the present invention have the desired ability to absorb liquids. Accordingly, small amounts of absorbent materials can be used to absorb large volumes of liquid. The desired ability to absorb liquids increases the cost-effectiveness of real absorbent materials. They also do not need to be thrown away and replaced with fresh absorbent materials as often as conventional absorbent materials. This reduces environmental concerns. In addition, in the present invention, secondary fiber pulp is used as raw material, the disposal of which is usually included in the manufacturer's overhead. Thus, embodiments of the present invention can be used to significantly reduce manufacturing costs for absorbent materials.

 These absorbent materials have low bulk densities that allow the consumer to easily handle them. Methods for preparing the present absorbent materials from recycled fiber pulp are simple and include a minimum number of process steps. Thus, when applying the methods of the present invention, there is no need for additional process steps, such as severe dewatering of the pulp, destruction or grinding of the fibers, and / or cutting the crusts of the dehydrated pulp into small pieces, which may be required in connection with the preparation of prototype absorbent materials from fiber pulp .

 These and other aspects of the invention will be more apparent on the basis of the present description and claims.

DETAILED DESCRIPTION OF THE INVENTION
Unless otherwise indicated, it should be understood that the following terms used above and throughout the description have the following meanings.

 "Recycled fiber pulp" refers to the main compressible solid waste coming from a dewatering device in a factory, for example in a paper recycling plant, from thin paper that processes waste paper into recycled fiber. The pulp of the secondary fiber is mainly composed of water, cellulose fiber and other additives used in the manufacture of paper, including adhesives, fillers, dyes, pigments, coating materials and printing inks. Secondary fiber sludge usually has a dark gray color when wet and a light gray color after drying.

 The term "undestructed" refers to a pulp of a secondary fiber, which is a pulp that has not been crushed or pulverized, for example by means of a reduction mill or grinder. Typically, the pulp of an undamaged secondary fiber is a pulp that can be transported using a mechanical conveyor and fed to a granulating device.

 The term "uncut" refers to the crust of a pulp of a secondary fiber that has not been cut into small pieces after being dehydrated.

 The term "wet granules" refers to granules formed from pulp of a secondary fiber, before drying.

 The term "liquid absorbency" refers to the ability of the absorbent materials described herein to absorb liquid. The ability to absorb liquids is expressed as the weight of the liquid absorbed by the absorbent material divided by the weight of the absorbent material.

 The term “%” or “percent” refers to percent by weight.

 The absorbent materials provided herein are highly absorbent and can be used to absorb various fluids, including non-polar fluids, such as petroleum based fluids, such as oil and grease, polar fluids, such as aqueous fluids, such as water and urine, as well as solvents, including organic solvents. These absorbent materials are very suitable for absorbing accidentally spilled liquids on surfaces, such as spilled oil and solvents on floors, workbenches and driveways. The present absorbent materials are also particularly suitable as animal litter, especially cat litter, for absorbing animal urine and other liquid wastes. The methods of the present invention relate to environmental problems associated with the disposal of recycled fiber pulp. The methods proposed here are simple and can be implemented with minimal equipment. As a result, the manufacture of these absorbent materials can be carried out, for example, inside or near the waste paper processing factory. Thus, there is no need to transport the pulp of the secondary fiber to a separate production device.

 The present invention relates in part to methods for producing absorbent material. The methods include the use of pulp of a secondary fiber having a moisture content of more than about 40%. Depending on the operations carried out in a particular waste paper processing plant, the pulp of the secondary fiber may also include the secondary pulp. Secondary pulp consists mainly of microbial biomass. However, due to safety and environmental considerations, the pulp of the secondary fiber preferably contains essentially little or no secondary pulp.

 The ash content of the pulp of the secondary fiber indicates the amount of additives that are introduced into the waste paper. Typically, the ash content of the pulp of the secondary fiber is from about 20 to about 80%. Waste paper containing a lot of filler and coating materials, such as magazines, leads to a secondary fiber pulp having a high ash content. Pulp from recycled paper recycling factories typically has low ash content. A typical ash sample consists of the following materials.

Material -%
Si as SiO ₂ - 46.4
Al as Al ₂ O ₃ - 40.6
Fe as Fe ₂ O ₃ - 1.5
Ti as TiO ₃ - 1.5
Ca like CaO - 7.4
Mg as MgO - 0.9
Na as Na ₂ O - 0.3
K as K ₂ O - zero
S as SO ₂ - 0.3
P as P ₂ O ₅ - 0.8
Losses during combustion at 900 ^o F (482.22 ^o C) - 0.1
Not defined - 0.2
Total - 100.0
A.N. Nadelman and LP Neston, TAPPI, vol. 43 (2), p. 120 (1960).

 The ash content of the secondary fiber pulp used in the methods of the present invention may vary and depends, for example, on the factory from which the secondary fiber pulp is obtained, the specific components introduced into the secondary fiber pulp, and the like. In preferred embodiments, the secondary fiber pulp has a low ash content. This is because ash, which is usually a measure of the concentration of inorganic materials present in the pulp, does not make a significant contribution to the ability to absorb liquids for the absorbent materials obtained from it.

 The ash content of the pulp of the secondary fiber is preferably less than about 80%, with more than an ash content of less than about 75%. Even more preferably, the pulp of the secondary fiber has an ash content of less than about 70%, with even more preferred ash content of less than about 65%. Even more preferably, the pulp of the secondary fiber has an ash content of less than about 60%, with even more preferably an ash content of less than about 55%. Even more preferably, the pulp of the secondary fiber has an ash content of less than about 50%, for example about 47%, with even more preferred ash content of less than about 45%. It is even more preferable that the pulp of the secondary fiber has an ash content of less than about 40%, with more than an ash content of less than about 35%. Even more preferably, the pulp of the secondary fiber has an ash content of less than about 30%, with even more preferably an ash content of less than about 25%. A particularly preferred ash content of the secondary fiber pulp is about 23%.

 As indicated above, the secondary fiber pulp used in the present methods has a moisture content of more than about 40%. As will be discussed in detail below, the moisture content of the pulp of the secondary fiber is an important factor and can affect the ease with which the pulp is processed into granules, as well as the ability to absorb liquids of the final absorbent materials. Preferably, the pulp of the secondary fiber has a moisture content of from more than about 40% to about 70%. More preferably, the moisture content of the pulp is from about 42% to less than about 70%, with even more preferably the moisture content of from about 50% to less than about 70%. Even more preferably, the moisture content of the pulp is from about 55% to less than about 70%, and even more preferably, the moisture content from about 60% to less than about 70%. Particularly preferred is a moisture content of from more than about 60% to about 68%, more preferably from more than about 60% to about 66%, and even more preferably about 63%.

 Secondary fiber pulp typically contains from about 50 to about 70% moisture. To reduce moisture content, the pulp can be dehydrated using any suitable dehydration device, for example, a felt (belt) press or a worm press. Of course, the moisture content of the pulp of the secondary fiber can be increased by adding water.

 After receiving the pulp of the secondary fiber with a moisture content of more than about 40%, the pulp is granulated to form wet granules. Although it is believed that a wide variety of granulating devices are available and can be used for granulating the pulp, it has been found that certain devices are preferred for this operation, and especially devices such as granular batch granulators. In a granulator of a periodic profile, the head has the shape of a metal ring. During operation, the head is rotated about two or three times to compress and extrude the pulp of the secondary fiber. Extrusion force in a granulator of a periodic profile of the tangential surface of the head. Thus, although the pulp gradually forms a mat on the surface of the head, nevertheless, the pulp can be continuously pushed out of the head without blockages.

 It has been found that certain granulating devices, including granulating devices, in which the extrusion force is applied in a direction different from the tangential to the surface of the head, such as screw extruders, are less preferred in the granulation operation than granular granulating devices. This is because other extruder devices have an increased tendency to clog. In this regard, in screw extruders, the pulp of the secondary fiber is extruded through a flat head having many holes. In screw extruders, the extrusion force is perpendicular to the surface of the head. During operation, the pulp gradually forms a mat on the surface of the head, which clogs the holes in the device.

 In order to cut the extruded pulp into wet granules of the required length, you can use adjustable cutting knives. Preferably, the wet granules have a diameter of from about 3/32 inch (0.24 cm) to about 1/4 inch (0.64 cm) and a length of from about 1/8 inch (0.32 cm) to about 1.2 inch ( 1.28 cm). More preferably, the wet granules have a diameter of from about 1/8 inch (0.32 cm) to about 3/16 inch (0.48 cm) and a length of from about 3/16 inch (0.48 cm) to about 5/16 inches (0.80 cm).

 As noted above, the moisture content of the pulp of the secondary fiber can significantly affect the further processing of the pulp into granules. If the pulp of the secondary fiber has a high moisture content, for example, about 70% or more, then during extrusion, water is expelled from the pulp. This leads to the formation of separate phases of water and pulp. In addition, the obtained wet granules do not have structural integrity and tend to stick together before drying. When the moisture content of the secondary fiber pulp is less than about 70%, water ejection during extrusion is substantially prevented. In addition, when the moisture content is below about 70%, the structural integrity of the wet granules is significantly improved. The tendency of wet granules to stick together can be substantially eliminated by using a pulp of a secondary fiber having a moisture content of less than about 65%. However, when the moisture content of the pulp decreases below about 42%, for example about 40%, its ability to deform in the cold state decreases. As a result, when extruding pulp of a secondary fiber with a moisture content of about 40%, difficulties are encountered, and there is an increased tendency to clog the granulator heads. Accordingly, in preferred embodiments of the present invention, the moisture content of the pulp of the secondary fiber is more than about 40%, for example at least about 42%. When the moisture content drops below about 40%, repeated blockage of the heads occurs, and with a moisture content of about 25% or less, the blockage is severe and requires the granulator to be turned off.

 In addition to affecting the formation of granules, the moisture content of the pulp of the secondary fiber can also have a noticeable effect on the ability to absorb liquids for the final granules. For example, it was observed that granules obtained from pulp of a secondary fiber with a higher moisture content, for example greater than about 40%, such as about 42%, have improved ability to absorb liquids relative to granules obtained from pulp of a secondary fiber having a lower moisture content for example, less than about 42%, such as about 40% or less. Although the inventor does not want to be bound by any theory of operation, the following reasons are given that granules obtained from pulp of a secondary fiber with a higher moisture content have improved liquid absorption capabilities. During drying, moisture in the wet granules evaporates, which creates empty spaces. These empty spaces can trap fluid. Granules obtained from pulp of a secondary fiber with a higher moisture content have more empty space compared to granules obtained from pulp of a secondary fiber having a lower moisture content. Granules having more empty spaces are capable of absorbing or capturing a larger volume of liquid.

 After the granules have been unloaded from the granulator, they are dried. A variety of drying means are available for drying wet granules, and such means will be apparent to one of ordinary skill in the art from the present description. The granules are preferably dried using a method in which they remain substantially stationary relative to each other, as a result of which friction movement is substantially avoided. As used herein, the term “friction motion” refers to the movement of granules in which the granules rub against each other or other surfaces, such as dryer walls. Friction movement is undesirable since it leads to erosion and / or destruction of the granules, as well as to the formation of fine particles and dust. In preferred embodiments, a conveyor dryer is used to dry wet granules. The use of a conveyor dryer minimizes the movement of granules with friction during the drying process, which leads to a significant elimination of the formation of dust or small particles. In contrast, other dryers, such as rotary dryers, can cause the destruction of granules and the creation of fine particles and dust, and their use should be avoided.

In preferred embodiments of the invention, the wet granules are dried to a moisture content of less than about 10%, with a moisture content of about 5% being more preferred. The desired moisture content in the dried granules can be achieved by heating the wet granules [at a temperature] from about 230 ^° F. (110.00 ^{° C.} ) to about 260 ^° F. (126.67 ^{° C.} ) for a period of from about 5 to about 10 minutes. In order to heat the wet granules to the required temperature and dry the granules to the desired moisture content, a variety of heat sources are available. Suitable heat sources include, for example, steam and natural gas. After drying, the dried granules can be cooled using ambient air.

 Optionally, deodorant and / or fragrance can be added to absorbent materials. This introduction can occur during processing of the pulp of the secondary fiber, for example after dehydration and before granulation, or after drying. The introduction of a deodorant and / or fragrance may be particularly desirable in the case of absorbent materials used as bedding for animals. The particular deodorant and / or fragrance chosen may vary and depends, for example, on the intended end use. Suitable deodorants or fragrances include, for example, cat litter deodorants commercially available from Church & Dwight Co, Inc. (Princeton, NJ), or baking soda.

 The absorbent materials of the present invention desirably have high fluid absorption capabilities. In preferred embodiments of the invention, the present absorbent materials have the ability to absorb liquids of at least about 1.1, with more preferred the ability to absorb liquids of more than about 1.1, for example 1.2, about 1.3, or about 1.4. Even more preferably, the absorbent materials have an ability to absorb liquids of at least about 1.5, with even more preferred the ability to absorb liquids of at least about 1.6. In an even more preferred embodiment, the absorbent materials have the ability to absorb liquids of more than about 1.6.

 The absorbent materials of the present invention desirably have low bulk densities, which makes handling easier for consumers. It has been observed that absorbent materials having lower bulk densities are typically obtained from pulp from a secondary fiber having a lower ash content. We believe that this is because the particle size of the ash is usually much smaller than the particle size of the fiber, and particles of a smaller size usually form granules having higher bulk densities.

In preferred embodiments, the present absorbent materials have a bulk density of less than about 36 lb / ft ³ (0.576 g / cm ³ ), for example about 35, 34, 33, 32 and 31 lb / ft ³ (0.560, 0.544, 0.528, 0.512 and 0.496 g / cm ³ ). More preferably, the absorbent materials have bulk densities of less than about 30 lb / ft ³ (0.480 g / cm ³ ), such as about 29, 28, 27, 26, 25, 24, 23, 22, 21, and 20 lb / ft ³ (0.464, 0.448, 0.432, 0.416, 0.400, 0.384, 0.368, 0.352, 0.336, and 0.320 g / cm ³ ), or less.

 The present absorbent materials can be used to absorb liquids, for example liquids spilled on surfaces, such as oil-based liquids, including oil. The spilled liquid is absorbed by contacting the absorbent material with the liquid, for example by applying an absorbent material to the spilled liquid. The absorbent material is allowed to absorb liquid, and the wetted absorbent material can be collected for suitable removal.

 The absorbent materials of the present invention are particularly suitable for use as animal bedding. The absorbent material is placed in a litter tray and brought into contact with the secretions of an animal, such as a domestic animal such as a cat, by excreting the animal into the absorbent material. The absorbent material used is easy to remove, for example by flushing to the toilet.

 The invention is further described in the following examples. These examples are real and are intended for illustrative purposes only and are not intended to limit the appended claims.

EXAMPLES
Examples 1-5 and 7 describe the preparation of granular absorbent materials falling within the scope of the present invention. Example 6 describes the preparation of granular absorbent materials not falling within the scope of the present invention. Examples 8-13 describe tests to evaluate the ability to absorb liquids for absorbent materials obtained in examples 1-7, as well as for prototype absorbent materials.

 Examples 1-12 are real examples, while example 13 is a predictive example.

EXAMPLE 1
Recycled fiber pulp from a recycling plant in the United States of America was used to make absorbent material. The pulp was dehydrated using a belt press to a moisture content of approximately 65% and an analysis was performed showing that the ash content of the pulp was approximately 23%. The pulp was fed directly into a granulator of a periodic profile and granulated. Wet granules were dried to a moisture content of less than 10% using laboratory drying ovens or drying equipment with a conveyor belt.

EXAMPLES 2-6
Example 1 was repeated, except that before granulation, the pulp was dehydrated to a moisture content of about 70% (example 2), about 60% (example 3), about 50% (example 4), about 42% (example 5), and about 30% ( example 6).

EXAMPLE 7
Example 3 was repeated, with the exception that the pulp of the secondary fiber was obtained from a recycling factory from Canada. Analysis showed an ash content of this pulp of approximately 47%.

EXAMPLE 8
For the granules obtained in Examples 1-7, bulk density (lb / ft ³ ) and water absorbency (in grams of absorbed water per gram of dry granules) were evaluated. The results of this assessment are presented in table 1.

 When considering table 1, it appears that the absorbent materials representing the preferred embodiments of the present invention (examples 1-5) have lower bulk densities and improved ability to absorb water in comparison with the absorbent materials obtained in example 6. Granules obtained from the pulp of the secondary fiber with a moisture content of at least 50% and higher (Examples 1-4) exhibit particularly improved water absorbency. In addition, consideration of Table 1 indicates that the ability to absorb water improves with an ash content of less than about 47%.

EXAMPLE 9
This example relates to the determination and comparison of bulk densities and water absorption abilities for the granules obtained in Example 3 and for two commercially available clay bedding for cats. The results of this determination are presented in table.2.

 When studying table 2, it turns out that the absorbent materials of the present invention have lower bulk densities and improved ability to absorb water in comparison with clay bedding for cats in the prior art.

EXAMPLE 10
This example relates to the evaluation and comparison of bulk densities and oil absorbency for granules obtained in Example 3, shredded waste paper and commercially available clay absorbent.

 The results of this determination are presented in table. 3.

 When studying the table. 3, it appears that the absorbent materials of the present invention have lower bulk densities than the prototype clay litter and improved oil absorbency compared to prior art clay litter for cats. Although shredded paper has a lower bulk density and a greater ability to absorb oil than the granules of Example 3, it is also significantly more expensive than the absorbent materials of the present invention, since it uses a product with commercial value as a raw material.

EXAMPLE 11
In this example, the effect of granule size on the ability to absorb liquid is evaluated. Granules were made with six different sizes, all of which are expressed in inches:
(A) diameter 3/32 (0.24 cm) and length 3/16 (0.48 cm);
(B) diameter 3/32 (0.24 cm) and length 7/16 (1.12 cm);
(C) diameter 1/8 (0.32 cm) and length 3/16 (0.48 cm);
(D) diameter 1/8 (0.32 cm) and length 7/16 (1.12 cm);
(E) 1/4 (0.64 cm) diameter and 3/16 (0.48 cm) length; and
(F) 1/4 (0.64 cm) diameter and 7/16 (1.12 cm) length.

 Water absorbency determinations were made for granules (A) to (F). The results of these determinations are given in table.4.

 When studying the table. 4, it appears that granules having a diameter greater than 3/32 inch (0.24 cm), shorter granules, and in particular granules 3/16 inch (0.48 cm) in length, have improved water absorption properties. Among the granules of six sizes evaluated in this example, granules of size (C) have the greatest ability to absorb water.

EXAMPLE 12
The absorbent materials of the present invention were distributed among the households of the cats. Absorbent materials were evaluated by cat owners for their effectiveness as bedding for cats. Cat owners reported that the absorbent materials of the present invention were effective as bedding for cats in that they:
(A) well absorb liquid;
(B) essentially do not tend to adhere to the paws of cats;
(C) substantially free of dust;
(D) create ease of cleaning of the litter pan;
(E) require little or no maintenance between shifts with a fresh absorbent;
(F) can be washed off and therefore easily removed;
(G) essentially do not tend to scatter from the litter pan; and
(H) Outwardly attractive to the cat owner.

 It is also reported that these absorbent materials are attractive to cats when they are looking for a place to empty from urine and other feces.

EXAMPLE 13
The determination is repeated as in Example 12, except that the absorbent materials also contain an aromatic substance, a germicide and / or a bactericide. In addition to the above properties (A) to (H), it is understood that the absorbent material is an effective litter for animals, since it:
(I) absorbs odors;
(J) slows the growth of microbes;
(K) makes litter pallets less visible;
(L) has a pleasant smell; and
(M) leads to an increase in time between substitutions.

 Based on the foregoing description, various variations of the invention will be apparent to those skilled in the art, other than those described herein. It is assumed that such options also fall within the scope of the attached claims.

Claims (22)

 1. A method of producing an absorbent material, comprising obtaining pulp of undamaged and uncut secondary fiber having a moisture content in the range of from more than about 40 to about 70% by weight, granulating said pulp of the secondary fiber to form wet granules by extruding the secondary fiber pulp through a die with extrusion force tangential to the surface of the head, and drying said wet granules.  2. The method according to claim 1, characterized in that said secondary fiber pulp has a moisture content of from about 42 to less than about 70 wt.%.  3. The method according to claim 2, characterized in that said secondary fiber pulp has a moisture content of from about 50 to about 66 wt.%.  4. The method according to claim 1, characterized in that it includes granulating the specified pulp of the secondary fiber using a granulator of a periodic profile.  5. The method according to claim 1, characterized in that during drying, said wet granules remain substantially stationary with respect to each other.  6. The method according to claim 5, characterized in that it includes drying said granules using a conveyor dryer.  7. A method of obtaining an absorbent material, comprising obtaining a pulp of a secondary fiber having a moisture content of greater than about 50 wt.%, To less than about 70 wt.%; granulating said pulp to form wet granules by extruding the secondary pulp fiber through the head with an extrusion force tangential to the surface of the head, and drying said wet granules.  8. The method according to claim 7, characterized in that it includes obtaining pulp of the secondary fiber from the factory for the refinement of waste paper from thin paper.  9. Absorbent material for absorbing liquid, including dry granules obtained from the pulp of undamaged and uncut secondary fiber having a moisture content of more than about 40 wt.%, And formed by extruding the pulp through the head with an extrusion force tangential to the surface of the head, with the formation of wet granules by evaporating moisture from the wet granules during the drying process to form dry granules having a moisture content of less than about 10 wt.%.  10. The absorbent material according to claim 9, characterized in that it is selected from the group consisting of absorbent liquid industrial waste and litter for animals.  11. Absorbent material according to claim 10, characterized in that said litter for animals is a litter for cats.  12. The absorbent material according to claim 9, characterized in that the said pulp of the secondary fiber has an ash content of less than about 80 wt.%.  13. The absorbent material according to claim 9, characterized in that the pulp has a moisture content of from more than about 40 to about 70 wt.%.  14. The absorbent material according to claim 9, characterized in that the pulp has a moisture content of from more than about 42 to about 70 wt.%.  15. The absorbent material according to claim 9, characterized in that the material additionally is an absorbent liquid industrial waste.  16. The absorbent material according to claim 9, characterized in that the dry granules have the ability to absorb liquid more than about 1: 1.  17. The absorbent material according to claim 9, characterized in that the dry granules have a moisture content of less than about 5 wt.%.  18. A method of absorbing liquid, comprising contacting the liquid with an absorbent material, which is obtained by a method comprising (a) obtaining pulp of an undamaged and uncut secondary fiber having a moisture content in the range of from more than about 40 to about 70 wt.%, (B) granulation the specified pulp of the secondary fiber with the formation of wet granules by extruding the pulp of the secondary fiber through the head with an extrusion force tangential to the surface of the head, and (c) drying the specified wet granules.  19. The method according to p. 18, characterized in that the liquid is selected from the group consisting of solvents, aqueous liquids and liquids based on oil.  20. The method according to p. 19, characterized in that the said aqueous liquid contains a liquid stool of the animal.  21. The method according to claim 20, characterized in that the liquid stool of the animal contains urine.  22. The method according to claim 19, characterized in that said oil-based liquid contains oil or grease.

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