TWI726234B - Method and system for recovering pulp fibers from used absorbent articles - Google Patents

Abstract

Provided is a method for removing the superabsorbent polymer with high processing efficiency from the pulp fiber of the residual superabsorbent polymer separated from the used absorbent article. The present invention is a method for recovering pulp fibers from used absorbent articles containing pulp fibers and superabsorbent polymers. The method is equipped with: a solid-liquid separation process (S18). The pulp fiber and the inactivated aqueous solution of the super absorbent polymer separated from the absorbent article are separated into a solid containing the pulp fiber and the super absorbent polymer, and a liquid containing the super absorbent polymer and the inactivated aqueous solution, While crushing the super absorbent polymer; and the oxidizing agent treatment process (S19), which is to treat the pulp fiber contained in the separated solid and the crushed super absorbent polymer with an aqueous solution containing an oxidizing agent.

Description

Method and system for recovering pulp fibers from used absorbent articles

The present invention relates to a method and system for recovering pulp fibers from used absorbent articles.

A method for recovering pulp fibers from absorbent articles such as disposable diapers after use is known. For example, Patent Document 1 discloses a method of manufacturing and reclaiming pulp from used sanitary products. This method is equipped with: in an acidic aqueous solution, etc., physical force is applied to the used sanitary products, and the used sanitary products are decomposed into pulp fibers and other materials; a mixture of pulp fibers and other materials In the process of separating pulp fibers; and the process of treating separated pulp fibers with ozone-containing aqueous solutions. By treating the pulp fiber with an ozone-containing aqueous solution, the superabsorbent polymer remaining in the separated pulp fiber is oxidatively decomposed, reduced in molecular weight, and dissolved, and can be removed by the pulp fiber. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2016-881

(The problem to be solved by the invention)

In order to make the pulp fibers recovered from the used absorbent articles more useful, it is extremely important to reduce the concentration of the superabsorbent polymer in the pulp fibers, or to improve the treatment efficiency of reducing the concentration of the superabsorbent polymer. In the method of Patent Document 1, by treating pulp fibers with an ozone-containing aqueous solution, the superabsorbent polymer remaining on the pulp fibers is oxidatively decomposed and can be removed from the pulp fibers. However, the treatment time with the ozone-containing aqueous solution is relatively long, and there is room for improvement from the viewpoint of improving the treatment efficiency. A technology for removing the superabsorbent polymer from the pulp fiber of the residual superabsorbent polymer separated from the used absorbent article with high processing efficiency is desired.

The object of the present invention is to provide a method and system for removing the superabsorbent polymer from the pulp fiber of the residual superabsorbent polymer separated from the used absorbent article with high processing efficiency. (Means to solve the problem)

The method of recovering the pulp fiber from the used absorbent article containing pulp fiber and superabsorbent polymer in this invention is as follows. (1) A method for recovering pulp fibers from used absorbent articles, which is a method for recovering pulp fibers from used absorbent articles containing pulp fibers and superabsorbent polymers, and the method includes: solid-liquid The separation process involves separating the inactivated aqueous solution containing the pulp fiber and super absorbent polymer separated from the used absorbent article into a solid containing the pulp fiber and the super absorbent polymer, and A liquid containing the aforementioned super absorbent polymer and the aforementioned inactivated aqueous solution, while crushing the aforementioned super absorbent polymer contained in the aforementioned solid; and an oxidizing agent treatment process, which is the aforementioned pulp contained in the separated solid The fiber and the crushed super absorbent polymer are treated with an aqueous solution containing an oxidizing agent. This method crushes the water-absorbed gel-like (block or roughly spherical) superabsorbent polymer remaining in the pulp fiber (for example: crushed by pressure higher than the gel strength) to make The thickness of the superabsorbent polymer becomes thinner, and it is formed into a flat shape or a finely divided shape. That is, this method can expand the surface area of the superabsorbent polymer by crushing the block or roughly spherical superabsorbent polymer, and increase the inner surface of the superabsorbent polymer. Partially exposed on exposed parts such as the front side. Therefore, in the oxidizing agent treatment process, if it is a block or roughly spherical superabsorbent polymer, the inner part of the superabsorbent polymer that is difficult to contact with the oxidizing agent can be contacted with the oxidizing agent, etc., and the superabsorbent can be increased. The area of contact with the oxidant in the polymer. Thereby, the oxidative decomposition of the super absorbent polymer can be progressed more efficiently, and the time for the oxidizing agent treatment can be shortened. Therefore, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved. Here, as an oxidant, ozone, chlorine dioxide, peroxyacetic acid, sodium hypochlorite, hydrogen peroxide, etc. are listed.

This method may also be (2) the method described in (1) above, wherein the solid-liquid separation process includes: a crushing process, which combines the inactive pulp fibers and the superabsorbent polymer. The aqueous solution is treated by a pressurized dehydration method to crush the superabsorbent polymer remaining in the pulp fiber. This method crushes the superabsorbent polymer remaining on the pulp fiber by the pressurized dehydration method, so that the solid-liquid separation and the pressure of the superabsorbent polymer on the pulp fiber can be efficiently and reliably performed at the same time. broken. That is, this method can efficiently and surely expand the surface area of the superabsorbent polymer on the pulp fiber to a larger extent. Thereby, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved. Among them, the super absorbent polymer system remaining on the pulp fiber is exemplified as the super absorbent polymer attached to the surface of the pulp fiber.

This method may also be (3) the method described in (2) above, wherein the pressure during the pressurization of the pressurized dehydration method in the crushing process is 0.02 MPa or more and 0.5 MPa or less. In this method, the pressure during the pressurization of the pressurized dehydration method is set to 0.02 MPa or more and 0.5 MPa or less. Therefore, this method does not damage the pulp fibers, but can sufficiently crush the superabsorbent polymer remaining in the pulp fibers, and therefore can sufficiently expand the surface area of the superabsorbent polymer. Thereby, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved. However, if the pressure is less than 0.02 MPa, the super absorbent polymer cannot be crushed sufficiently. Therefore, the oxidant treatment time cannot be shortened. If the pressure is greater than 0.5 MPa, the super absorbent polymer can be sufficiently reduced. Crushing, but there is a risk of damaging the pulp fibers.

This method may also be (4) the method of any one of (1) to (3) above, wherein, prior to the solid-liquid separation process, the method is additionally provided with: comprising the pulp fiber and the super absorbent polymer The said inactivation aqueous solution is a process of separating a part of the said super absorbent polymer and the said inactivation aqueous solution. In this method, before the solid-liquid separation process, a certain amount of super absorbent polymer and the inactivated aqueous solution are separated from the inactivated aqueous solution containing the pulp fiber and the super absorbent polymer. Therefore, this method can suppress the ratio of the super absorbent polymer in the materials (pulp fiber, super absorbent polymer, and inactivated aqueous solution) supplied in the solid-liquid separation process to a low level. Thereby, in the solid-liquid separation process, the super absorbent polymer adhering to the pulp fiber can be crushed more efficiently, and the processing efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

This method may also be (5) the method of any one of (1) to (4) above, wherein the ratio of the super absorbent polymer in the inactivated aqueous solution supplied in the solid-liquid separation process Department below 50%. In this method, in the solid-liquid separation process, the ratio of the superabsorbent polymer in the inactivated aqueous solution to be separated is 50% or less. Thereby, since there is no need to crush an excessive amount of super absorbent polymer, the super absorbent polymer can be crushed more reliably and efficiently. Thereby, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

This method may also be (6) the method of any one of (1) to (5) above, wherein, before the solid-liquid separation process, the method is additionally provided with: inactivating the used absorbent article A process of crushing in an aqueous solution; and a process of separating an inactivated aqueous solution containing pulp fibers and a super absorbent polymer from the inactivated aqueous solution containing the crushed material obtained in the foregoing crushing process. In this method, through the process of crushing and the process of separating, the inactive material containing the pulp fiber separated from the used absorbent article and the super absorbent polymer supplied in the solid-liquid separation process is generated.化液。 Water solution. This can prevent foreign matter (pulp fibers of disposable absorbent articles and materials other than superabsorbent polymers (examples: films (back sheets, etc.)), non-woven fabrics (surface sheets, etc.) from being mixed in the inactivated aqueous solution. Elastomers (rubbers for leak-proof walls, etc.). With this, the super absorbent polymer can be crushed more accurately without being hindered by foreign matter. As a result, the removal of the super absorbent polymer from the pulp fiber can be improved The processing efficiency.

This method may also be (7) the method of any one of (1) to (6) above, wherein the inactivation aqueous solution is an acidic aqueous solution. In this method, since the inactivation aqueous solution is an acidic aqueous solution, the superabsorbent polymer in the used absorbent article can be surely dehydrated and formed into a predetermined size (example: particle size) or less. Thereby, it is possible to easily crush the super absorbent polymer while performing solid-liquid separation in the solid-liquid separation process. As a result, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

This method may also be (8) the method as described in (7) above, wherein the acidic aqueous solution has a pH of 2.5 or less. In this method, since the acidic aqueous solution has a pH of 2.5 or less, the superabsorbent polymer in the used absorbent article can be dehydrated more reliably and be formed to a predetermined size (example: particle size) or less. Thereby, in the solid-liquid separation process, the super absorbent polymer can be crushed more easily while performing solid-liquid separation. As a result, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved. In addition, since the super absorbent polymer is formed into a predetermined size or less in the state of a gel, the super absorbent polymer can be easily crushed.

This method may also be (9) the method of (7) or (8) above, wherein the acidic aqueous solution contains citric acid. In this method, since the acidic aqueous solution contains citric acid (example: concentration 0.5 to 2.0% by mass), the super absorbent polymer in the used absorbent article can be reliably dehydrated and formed into a predetermined particle size or less . Thereby, it is possible to easily crush the super absorbent polymer while performing solid-liquid separation in the solid-liquid separation process. As a result, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

The system used in the present invention for recovering pulp fibers from used absorbent articles containing pulp fibers and superabsorbent polymers is as follows. (10) A system for recovering pulp fibers from used absorbent articles, which is a system for recovering pulp fibers from used absorbent articles containing pulp fibers and superabsorbent polymers, and the system is equipped with: solid-liquid Separating device, which separates the inactivated aqueous solution containing the pulp fiber and super absorbent polymer separated from the used absorbent article into a solid containing the pulp fiber and the super absorbent polymer, and A liquid containing the aforementioned super absorbent polymer and the aforementioned inactivated aqueous solution, while crushing the aforementioned super absorbent polymer contained in the aforementioned solid; and an oxidizing agent treatment device which treats the aforementioned pulp contained in the aforementioned solid after separation The fiber and the crushed super absorbent polymer are treated with an aqueous solution containing an oxidizing agent. This system crushes the water-absorbed gel-like (block or roughly spherical) superabsorbent polymer remaining in the pulp fiber (example: crushed by pressure higher than the gel strength) to make The thickness of the superabsorbent polymer becomes thin, and it is formed into a flat shape or a finely divided shape. In other words, this system can expand the surface area of the block or roughly spherical superabsorbent polymer by crushing the superabsorbent polymer, and increase the inner side of the superabsorbent polymer. The part exposed on the front side and the exposed part increase. Therefore, in the oxidizing agent treatment device, if it is a block or roughly spherical superabsorbent polymer, the inner part of the superabsorbent polymer that is difficult to contact with the oxidizing agent can be contacted with the oxidizing agent, etc., and the superabsorbent can be increased. The area of contact with the oxidant in the polymer. Thereby, the oxidative decomposition of the super absorbent polymer can be progressed more efficiently, and the time for the oxidizing agent treatment can be shortened. Therefore, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

This system may also be (11) the system as described in (10) above, wherein the solid-liquid separation device includes: a screw press dehydrator, which combines the aforementioned inactive pulp fibers and the aforementioned superabsorbent polymer The aqueous solution is treated by a pressurized dehydration method to crush the superabsorbent polymer remaining in the pulp fiber. This system crushes the superabsorbent polymer remaining in the pulp fiber by using the pressurized dewatering method of the screw press dehydrator, so it can efficiently and reliably perform the solid-liquid separation and the pulp fiber at the same time. The crushing of the super absorbent polymer. That is, this system can efficiently and surely expand the surface area of the superabsorbent polymer on the pulp fiber. Thereby, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved. Among them, the super absorbent polymer system remaining on the pulp fiber is exemplified as the super absorbent polymer attached to the surface of the pulp fiber.

This system may also be (12) the system of the above-mentioned (11), wherein the pressure during the pressurization of the pressurized dehydration method in the screw press dehydrator is 0.02 MPa or more and 0.5 MPa or less. In this system, the pressure during the pressurization of the pressurized dehydration method is 0.02 MPa or more and 0.5 MPa or less. Therefore, the system does not damage the pulp fibers, but can fully crush the super absorbent polymer remaining in the pulp fibers, so the surface area of the super absorbent polymer can be fully expanded. Thereby, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved. However, if the pressure is less than 0.02 MPa, the super absorbent polymer cannot be crushed sufficiently. Therefore, the oxidizing agent treatment time cannot be shortened. If the pressure is greater than 0.5 MPa, the super absorbent polymer can be fully compressed. Broken, but there is a risk of damaging the pulp fibers.

This system can also be (13) the system of any one of (10) to (12) above, in which it is additionally equipped with: a cylindrical screen type dehydrator, which is set before the solid-liquid separation process and includes the aforementioned The pulp fiber and the inactivated aqueous solution of the super absorbent polymer are separated from a part of the super absorbent polymer and the inactivated aqueous solution. This system is in front of the solid-liquid separation device, using a cylindrical screen dehydrator to separate a certain amount of super absorbent polymer and inactivated aqueous solution from an inactivated aqueous solution containing pulp fiber and super absorbent polymer . Therefore, this system can suppress the ratio of the super absorbent polymer in the materials (pulp fiber, super absorbent polymer, and inactivated aqueous solution) supplied in the solid-liquid separation process to a low level. Thereby, the screw press type dehydrator can more efficiently crush the super absorbent polymer adhering to the pulp fiber, and the processing efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

This system may also be (14) the system of any one of (10) to (13) above, wherein the ratio of the super absorbent polymer in the inactivated aqueous solution supplied to the solid-liquid separation device is based on Less than 50%. In this system, in the solid-liquid separator, the ratio of the superabsorbent polymer in the inactivated aqueous solution to be separated is 50% or less. Thereby, since there is no need to crush an excessive amount of super absorbent polymer, the super absorbent polymer can be crushed more reliably and efficiently. Thereby, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

This system may also be (15) the system of any one of (10) to (14) above, wherein the aforementioned inactivated aqueous solution is an acidic aqueous solution. In this system, since the inactivation aqueous solution is an acidic aqueous solution, the superabsorbent polymer in the used absorbent article can be surely dehydrated and formed into a predetermined particle size or less. Thereby, the super absorbent polymer can be crushed easily while performing solid-liquid separation in the solid-liquid separation device. As a result, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

This system may also be (16) the system as described in (15) above, wherein the aforementioned acidic aqueous solution has a pH of 2.5 or less. In this system, since the acidic aqueous solution has a pH of 2.5 or less, the superabsorbent polymer in the used absorbent article can be dehydrated more reliably and be formed to a predetermined particle size or less. Thereby, in the screw press type dehydrator, the super absorbent polymer can be crushed more easily while the solid-liquid separation is performed. As a result, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved. In addition, since the super absorbent polymer is formed into a predetermined particle size or less in a gel state, the super absorbent polymer can be easily crushed.

This system may also be (17) the system as described in (15) or (16) above, wherein the aforementioned acidic aqueous solution contains citric acid. In this system, since the acidic aqueous solution contains citric acid (example: concentration 0.5 to 2.0% by mass), the superabsorbent polymer in the used absorbent article can be surely dehydrated and formed into a predetermined particle size or less. Thereby, it is possible to easily crush the super absorbent polymer while performing solid-liquid separation in the screw press type dehydrator. As a result, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved. (Effects of the invention)

With the method and system of the present invention, the pulp fiber of the residual super absorbent polymer separated from the used absorbent article can be removed with high treatment efficiency.

Hereinafter, a method of recovering pulp fibers from a used absorbent article containing pulp fibers and a super absorbent polymer according to the embodiment will be described. Among them, the used absorbent article refers to the absorbent article used by the user, including the absorbent article that absorbs/maintains the excrement of the user, and also includes those that have not absorbed/maintained the excrement after use, Or those who have not been used but have been discarded. Examples of absorbent articles include diapers, urine pads, sanitary napkins for menstrual periods, bed sheets, and pet sheets. Among them, the method of recovering pulp fibers from used absorbent articles in the present embodiment is to generate recycled pulp fibers, so it can also be referred to as a method of generating recycled pulp fibers from used absorbent articles. In addition, the method of recovering pulp fibers from used absorbent articles in this embodiment is to recover the super absorbent polymer along with the pulp fibers on the way, and by separating, produce and recycle the super absorbent polymer, so it can also be described as A method of recovering a super absorbent polymer from a used absorbent article, or a method of producing and recovering a super absorbent polymer. This is explained as a method of recovering pulp fibers from used absorbent articles.

First, an example of the configuration of an absorbent article will be described. The absorbent article includes a top sheet, a back sheet, and an absorber arranged between the top sheet and the back sheet. As an example of the size of an absorbent article, the length is about 15 to 100 cm, and the width is 5 to 100 cm. Among them, the absorbent article may also include other other members provided in general absorbent articles, such as a diffusion sheet or a leak-proof wall.

As the structural member of the surface sheet, for example, a liquid-permeable nonwoven fabric, a synthetic resin film having liquid-permeable holes, and such composite sheets are listed. The constituent members of the back sheet include, for example, liquid-impermeable non-woven fabrics, liquid-impermeable synthetic resin films, and composite sheets of these. As the constituent member of the diffusion sheet, for example, a liquid-permeable non-woven fabric is cited. As a constituent member of the leakage prevention wall, for example, a liquid-impermeable non-woven fabric may be mentioned, and an elastic member such as rubber may be included. Here, the non-woven fabric or synthetic resin film material is not particularly limited if it can be used as an absorbent article. Examples include olefin resins such as polyethylene and polypropylene, 6-nylon, and 6,6-nylon. Polyamide resins, polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). In this embodiment, an absorbent article in which the constituent member of the back sheet is used as a film and the constituent member of the front sheet is used as a non-woven fabric will be described as an example.

In terms of the constituent members of the absorber, a series of examples include: absorber materials, namely pulp fibers and super absorbent polymers. The pulp fiber is not particularly limited as long as it can be used as an absorbent article, and examples include cellulose fibers. For cellulose fibers, for example, wood pulp, cross-linked pulp, non-wood pulp, regenerated cellulose, semi-synthetic cellulose, and the like are listed. In terms of the size of the pulp fiber, the average value of the fiber long diameter is, for example, several tens of μm, preferably 20 to 40 μm, and the average value of the fiber length is, for example, several mm, preferably 2 to 5 mm. In terms of superabsorbent polymer (SuperAbsorbent Polymer: SAP), if it can be used as an absorbent article, there is no particular limitation, for example: polyacrylate series, polysulfonate series, maleic anhydride salt series.性polymer. In terms of the size of the super absorbent polymer (when dried), the average particle size is, for example, several hundreds of μm, preferably 200 to 500 μm.

One surface and the other surface of the absorber are respectively bonded to the top sheet and the back sheet through the adhesive. In a plan view, the part (peripheral part) of the surface sheet that extends to the outside of the absorber so as to surround the absorber is through the adhesive and extends to the outside of the absorber so as to surround the absorber in the back sheet. The parts (peripheral parts) are joined. Therefore, the absorbent system is enclosed in the bonded body of the top sheet and the back sheet. There are no particular restrictions on the adhesive as long as it can be used as an absorbent article, and the adhesive strength is reduced by softening with warm water as described later, and examples include hot-melt adhesives. For hot-melt adhesives, for example, rubber-based bodies such as styrene-ethylene-butadiene-styrene, styrene-ethylene-styrene, styrene-isoprene-styrene, etc., or polyethylene Pressure sensitive adhesives or heat sensitive adhesives based on olefins.

Next, a method of recovering pulp fibers from a used absorbent article containing pulp fibers and a super absorbent polymer according to the embodiment will be described. In this embodiment, the used absorbent article is recycled/obtained from the outside for use for reuse (recycling). At this time, the used absorbent article is enclosed in a plurality of collection bags (hereinafter also referred to as "collection bags") so that dirt (excretion, etc.), fungi or odors will not escape to the outside. Each used absorbent article in the collection bag is designed so that the excrement will not be exposed on the surface and the odor will not spread to the surroundings. The surface sheet of the excreted excrement is used as the inner side, mainly in It is collected in a balled state or folded state.

First, the system 1 used in the method of recovering pulp fibers from used absorbent articles will be described. System 1 is a system in which pulp fibers (preferably even super absorbent polymers) are recovered from used absorbent articles, so that recycled pulp fibers (preferably even super absorbent polymers) are generated. Fig. 1 is a block diagram showing an example of the system 1 of this embodiment. The system 1 is provided with: a third separation device 18 and an oxidant treatment device 19, preferably with: a bag breaking device 11, a crushing device 12, a first separation device 13, a first dust removal device 14, a second dust removal device 15 , The third dust removal device 16, the second separation device 17, and the fourth separation device 20. The following is a detailed description.

First, the bag breaking device 11 and the crushing device 12 will be described. The bag breaking device 11 is a collection bag containing used absorbent articles, and holes are opened in the inactivated aqueous solution. The crushing device 12 crushes the used absorbent article in the inactivated aqueous solution sinking under the surface of the inactivated aqueous solution together with the collection bag. Among them, the inactivated aqueous solution refers to an aqueous solution in which the super absorbent polymer is inactivated. Due to the inactivation, the water absorption performance of the super absorbent polymer is reduced. Thereby, if the super absorbent polymer system absorbs more water than the reduced water absorption performance, the water is released, that is, it is dehydrated to an allowable amount with the water absorption performance. Hereinafter, a case where an acidic aqueous solution is used as the inactivation aqueous solution is used as an example for description.

Fig. 2 is a schematic diagram showing a configuration example of the bag breaking device 11 and the crushing device 12 of Fig. 1. The bag breaking device 11 accumulates, for example, an acidic aqueous solution B supplied through a pipe equipped with a valve, and opens a hole in the collection bag A put in the acidic aqueous solution B. The bag breaking device 11 includes a solution tank V and an opening 50. The solution tank V accumulates the acidic aqueous solution B. The opening part 50 is provided in the solution tank V. When the collection bag A is placed in the solution tank V, the surface of the collection bag A that is in contact with the acidic aqueous solution B is opened. The opening part 50 includes a feeding part 30 and a bag breaking part 40. The feeding part 30 feeds (introduces) the collection bag A (physically forcibly) into the acidic aqueous solution B in the solution tank V. The feeding part 30 series is, for example, an agitator, and includes a stirring blade 33, a support shaft (rotating shaft) 32 that supports the stirring blade 33, and a drive device 31 that rotates the support shaft 32 along the shaft. The stirring blade 33 is rotated around the rotating shaft (support shaft 32) by the driving device 31, thereby generating a swirling flow in the acidic aqueous solution B. The feeding part 30 introduces the collection bag A to the bottom direction of the acidic aqueous solution B (solution tank V) by swirling flow. The bag breaking part 40 is arranged at the lower part (preferably the bottom) of the solution tank V, and is provided with: a bag breaking blade 41, a support shaft (rotation shaft) 42 that supports the bag breaking blade 41, and a support shaft 42 along the axis Rotating drive device 43. The bag breaking blade 41 is rotated around the rotating shaft (support shaft 42) by the driving device 43, thereby opening a hole in the collecting bag A that moves to the lower part of the acidic aqueous solution B (solution tank V). Here, the lower part of the solution tank V indicates a portion lower than the half position of the solution tank V in the height direction. Among them, the bag breaking blade 41 of the opening 50 of the bag breaking device 11 may move in the up and down direction in the solution tank V while rotating around the rotating shaft (support shaft 42). At this time, since the bag breaking blade 41 moves upward, even if the collection bag A does not move to the lower part of the acid aqueous solution B (solution tank V), a hole can be opened in the collection bag A.

The crushing device 12 crushes the used absorbent article in the collection bag A sinking under the water surface of the acidic aqueous solution B together with the collection bag A. The crushing device 12 includes a crushing part 60 and a pump 63. The crushing part 60 is connected to the solution tank V by a pipe 61, and the used absorbent article (mixed solution 91) in the collection bag A sent out from the solution tank V together with the acidic aqueous solution B, together with the collection bag A Crushing occurs in the acidic aqueous solution B. For the crushing part 60, list: double-shaft crusher (example: double-shaft rotary crusher, double-shaft differential crusher, double-shaft shear type crusher), for example: SUMICUTTER (Sumitomo Heavy Machinery Environmental Co., Ltd. Limited company). The pump 63 is connected to the crushing part 60 by a pipe 62, and the crushed material obtained in the crushing part 60 is drawn from the crushing part 60 together with the acidic aqueous solution B (mixed liquid 92), and is sent to the next process. Among them, the crushed material system includes: pulp fiber, super absorbent polymer, and other materials (materials of the collection bag A, film, non-woven fabric, elastomer, etc.). The bag breaking device 11 and the crushing device 12 are preferably different devices from each other.

1, the first separating device 13 agitates the mixed liquid 92 of the crushed material obtained in the crushing device 12 and the acidic aqueous solution, and removes dirt (fecal matter, etc.) from the crushed material while washing the mixed liquid 92 The pulp fiber, the super absorbent polymer, and the acidic aqueous solution (mixed liquid 93) are separated, and sent to the first dust removal device 14. Taking the first separating device 13 as a series, for example, a washing machine equipped with a washing tank and a dehydrating tank and a water tank surrounding it. Among them, a washing tank and a dehydration tank (rotating drum) is used as a washing tank and a screen tank (separation tank). The size of the plurality of through holes provided on the peripheral surface of the washing tank is such a size that the pulp fiber and super absorbent polymer in the crushed material can pass easily but other materials are difficult to pass. The washing machine includes, for example, a horizontal washing machine ECO-22B (manufactured by Inamoto Seisakusho Co., Ltd.).

Among them, it is not necessary to break the used absorbent article together with the collection bag in the inactivated aqueous solution (example: acidic aqueous solution), and to break the used absorbent article together with the collection bag in the gas (example: air) The item is broken. At this time, the bag breaking device 11 is not required, and the breaking device 12 performs the breaking in the air without the inactivated aqueous solution. After that, the crushed material of the crushing device 12 and the inactivated aqueous solution are supplied to the first separating device 13.

Among them, if the acidic aqueous solution is not used as the inactivated aqueous solution between the bag breaking device 11 to the first separating device 13, the acidic aqueous solution may be added to the inactivated aqueous solution by the first dust removal device 14, and it will be supplied to the second 1 The inactivated aqueous solution containing the pulp fiber and the super absorbent polymer of the dust removal device 14 is substantially formed as an acidic aqueous solution. At this time, the specific gravity and size of the super absorbent polymer can be easily adjusted by pH.

The first dust removal device 14 maintains the pH within a predetermined range while passing the acidic aqueous solution (mixed solution 93) containing pulp fibers and superabsorbent polymers sent from the first separation device 13 through a sieve with a plurality of openings. , Separated into pulp fiber and super absorbent polymer (mixture 94) and other materials (foreign matter) in the acidic aqueous solution. In order to maintain the pH within a predetermined range, for example, a liquid (example: water) that changes the pH in the middle is not added, or when the liquid is added, it is formed into a liquid of approximately the same pH (example: an acidic aqueous solution). The predetermined range refers to the range within which the variation of pH is within ±1.0. The first dust removal device 14 series is, for example, a screen separator (coarse screen separator). However, the opening of the screen is not particularly limited. Examples include slits, round holes, square holes, and meshes. Here, round holes are used. The size of the opening, that is, the size (diameter) of the circular hole is formed so that the pulp fiber and super absorbent polymer can pass through, and it is difficult for other materials (foreign objects) that cannot be removed by the first separating device 13 to pass through. , And is larger than the width of the slit of the screen of the second dust removal device 15. The size of the circular hole is, for example, 2 to 5 mmφ in diameter, so that other materials (foreign objects) of at least 10 mm square can be removed. In the case of a slit, the size (width) of the slit is, for example, 2 to 5 mm. However, from the viewpoint of improving the efficiency of foreign matter removal, the mixed liquid 93 sent from the first separation device 13 may be supplied to the first dust removal device 14 while ^{pressurizing (example: 0.5 to 1 kgf/cm 2 ).} Examples of the first dust removal device 14 series include Pack Pulper (manufactured by SATOMI Mfg. Co., Ltd.).

The second dust removal device 15 maintains the pH within a predetermined range while passing the acidic aqueous solution (mixed liquid 94) containing pulp fibers and super absorbent polymers sent from the first dust removal device 14 through a sieve with multiple openings. , Separated into pulp fiber and super absorbent polymer (mixed liquid 95) and other materials (foreign matter) in the acidic aqueous solution. The second dust removal device 15 series is, for example, a sieve separator. Among them, the opening of the screen is not particularly limited. Examples include slits, round holes, square holes, and meshes. In this case, slits are used. The size of the slit (wide width) is a size that allows pulp fibers and super absorbent polymers to pass through, and is a size that makes it difficult for other materials (foreign objects) that cannot be removed by the first dust removal device 14 to pass through. The size of the slit is, for example, a width of 0.2 to 0.5 mm, so that other materials (foreign objects) of at least 3 mm square can be removed. In the case of a circular hole, the size (diameter) of the circular hole is, for example, a diameter of 0.2 to 0.5 mmφ. However, from the viewpoint of improving the efficiency of foreign matter removal, the mixed solution 94 sent from the first dust removal device 14 may be supplied to the second dust removal device 15 while ^{pressurizing (example: 0.5 to 2 kgf/cm 2 ).} From the viewpoint of removing relatively small foreign matter, the pressure is preferably higher than the pressure of the first dust removal device 14. The second dust removal device 15 is, for example, RAMOLT SCREEN (manufactured by Aikawa Iron Works Co., Ltd.).

The third dust removal device 16 maintains the pH within a predetermined range while centrifuging the acidic aqueous solution (mixed solution 95) containing pulp fibers and superabsorbent polymer sent from the second dust removal device 15 to separate the acidic aqueous solution The pulp fiber and super absorbent polymer (mixed liquid 96) are separated from other materials (heavy foreign matter). The third dust removal device 16 series is, for example, a cyclone separator. The pulp fiber and super absorbent polymer in the acidic aqueous solution with a relatively light specific gravity rise, and the foreign matter (metal, etc.) with a heavier specific gravity decreases. At a predetermined flow rate, the pulp fiber and super absorbent polymer will be included. The acidic aqueous solution (mixed liquid 95) of the polymer is supplied into the conical frame (not shown) in the opposite direction of the third dust removal device 16. The third dust removal device 16 is exemplified as an ACT low-concentration cleaner (manufactured by Aikawa Iron Works Co., Ltd.).

The second separating device 17 separates the acidic aqueous solution (mixed solution 96) containing pulp fibers and superabsorbent polymer sent from the third dust removal device 16 into the pulp fibers in the acidic aqueous solution through a sieve with a plurality of openings ( Mixed liquid 97), and super absorbent polymer in acidic aqueous solution. Therefore, it can be regarded as a dehydrator that removes the acidic aqueous solution from the mixed liquid 96 together with the super absorbent polymer. The series of the second separator 17 is, for example, a cylindrical screen separator. Among them, the opening of the cylindrical screen is not particularly limited, and examples thereof include slits, round holes, four corners, and meshes. In this case, slits are used. The size of the slit (wide width) is a size that allows the super absorbent polymer to pass through, and a size that is difficult for pulp fibers to pass through. If it is a slit, the size of the slit is, for example, a width of 0.2 to 0.8 mm, so that at least a large amount of super absorbent polymer can be removed. In the case of a circular hole, the size of the circular hole is, for example, a diameter of 0.2 to 0.8 mmφ. The second separator 17 is a cylindrical screen dehydrator (manufactured by Toyo Screen Co., Ltd.).

The third separating device 18 separates the pulp fibers sent from the second separating device 17 and the remaining superabsorbent polymer and acidic aqueous solution (mixed liquid 97) that cannot be separated by a sieve with a plurality of openings. The solid of pulp fiber and super absorbent polymer (mixture 98), and the liquid containing the super absorbent polymer and acidic aqueous solution, while applying pressure to the solid, crushes the super absorbent polymer in the solid. Therefore, the third separation device 18 can also be regarded as a dehydrator of the pressurized dehydration method in which the mixed liquid 97 removes the acidic aqueous solution together with the super absorbent polymer. Among them, the solid (mixture 98) is slightly acidic and water-soluble. Fig. 3 is a schematic diagram showing a configuration example of the third separation device 18 of Fig. 1. The third separation device 18 series is, for example, a screw press type dehydrator. The third separation device 18 includes, for example, a cylindrical screen 81, a screw shaft 82, a screw blade 83, a driving device 86, a cover 84, and a pressure regulating device 85. The cylindrical screen 81 is a cylindrical screen provided in the frame 80. The screw shaft 82 extends along the axis of the cylinder of the cylindrical screen 81, and its diameter gradually increases toward the front end of the cylindrical screen 81. The spiral blade 83 is spirally provided on the outside of the spiral shaft 82 and rotates along the inner peripheral surface of the cylindrical screen 81. The pitch of the spiral blades 83 may gradually become narrower toward the front end of the cylindrical screen 81. The driving device 86 rotates the screw shaft 82. The cover 84 is provided to close the front end of the cylindrical screen 81. The pressure adjusting device 85 adjusts the pressure of the pressing that presses the lid 84 against the front end of the cylindrical screen 81. Among them, the opening of the cylindrical screen 81 is not particularly limited, and examples thereof include slits, round holes, four corners, and meshes. In this case, slits are used. The size of the slit (wide width) is a size that allows the super absorbent polymer to pass through, and a size that is difficult for pulp fibers to pass through. If it is a slit, the size of the slit is, for example, 0.1-0.5 mm wide, so that at least the remaining super absorbent polymer can be removed. The third separating device 18 sends out the liquid E containing the super absorbent polymer and the acidic aqueous solution through the slit on the side of the cylindrical screen 81, while sending out the pulp fiber containing the pulp fiber through the gap G between the front end of the cylindrical screen 81 and the cover 84 Solid with super absorbent polymer (mixture 98). When the solid (mixture 98) is sent out, the super absorbent polymer is crushed. The pressure series of the pressing applied to the lid body is, for example, 0.01 MPa or more and 1 MPa or less. The third separating device 18 is a screw press dehydrator (manufactured by Kawaguchi Seiki Co., Ltd.).

The oxidizing agent treatment device 19 treats the pulp fibers (mixture 98) containing the super absorbent polymer crushed in solids sent from the third separation device 18 with an aqueous solution (treatment liquid) containing an oxidizing agent. Thereby, the super absorbent polymer is oxidized and decomposed to be removed from the pulp fiber, and the pulp fiber that does not contain the water absorbent polymer is sent out together with the treatment liquid (mixed liquid 99).

FIG. 4 is a schematic diagram showing a configuration example of the oxidant treatment device 19. The oxidant treatment device 19 uses ozone as the oxidant, and includes a pump 121, a treatment tank 123, a pump 125, an ozone generator 126, an ozone mixing device 127, and an ozone decomposition device 129. The processing tank 123 has an acidic aqueous solution as the processing liquid P, and the mixture 98 is supplied from the supply port 122b provided in the upper part. If ozone is used as an oxidant in the acidic aqueous solution, it is better to improve the stability of ozone. The pump 121 passes through the pipe 132, draws out the processing liquid P from the delivery port 124a at the bottom of the processing tank 123, and supplies it to the processing tank 123 from the supply port 122a at the upper part of the processing tank 123. The pump 125 passes through the pipe 136, draws out the processing liquid P from the delivery port 124b at the bottom of the processing tank 123, and supplies it to the processing tank 123 from the supply port 122c at the lower part of the processing tank 123. The ozone generator 126 generates the ozone-containing gas Z which is a gaseous substance, and supplies it to the ozone mixing device 127. The ozone mixing device 127 is located in the middle of the pipe 136, and mixes the ozone-containing gas Z supplied through the pipe 135 with the supply port 122c facing the lower part of the processing tank 123 and the processing liquid P circulating in the pipe 136. The ozone mixing device 127 forms the ozone-containing gas Z into a plurality of fine bubbles and supplies them to the processing liquid P. The ozone-containing gas Z is another type of gas containing ozone, and examples thereof include oxygen or air containing ozone. The ozone generator 126 includes, for example, an ozone water exposure tester ED-OWX-2 manufactured by EcoDesign Co., Ltd., an ozone generator OS-25V manufactured by Mitsubishi Electric Co., Ltd., and the like. The ozone decomposing device 129 collects the ozone-containing gas Z accumulated in the upper part of the processing tank 123 through the pipe 134, decomposes ozone, makes it harmless, and releases it to the outside. Among them, the treatment liquid P in the treatment tank 123 is initially only the treatment liquid P, and after the beginning is formed into a liquid in which the treatment liquid P and the mixture 98 are mixed, but in this embodiment, the system also includes a mixture of the treatment liquid P and the mixture 98. The liquid of the mixture 98 is the liquid in the processing tank 123 as the processing liquid P.

FIG. 5 is a schematic diagram showing another configuration example of the oxidant treatment device 19. The oxidant treatment device 19 is provided with: a mixed solution storage unit 110 that stores a mixture 98 containing pulp fibers together with the treatment solution Pa; and crushed super absorbent polymer contained in the pulp fibers in the treatment solution Pa, by The oxidizing agent treatment part 120 which is oxidized and decomposed by the treatment liquid P and removed from the pulp fiber. The mixed liquid storage unit 110 includes a mixed liquid tank 112 and a mixer 113. The mixed liquid tank 112 stores the mixture 98 containing pulp fibers supplied through the pipe 131 in the processing liquid Pa. The agitator 113 stirs in the processing liquid Pa in the mixed liquid tank 112 so that the mixture 98 does not sink below the processing liquid Pa. On the other hand, the oxidant processing unit 120 includes a pump 121a, a processing tank 123, an ozone supply device 128, a pump 125a, and an ozone decomposition device 129. The treatment tank 123 has an acidic aqueous solution as the treatment liquid P. The pump 121a continuously supplies the processing liquid Pa containing the mixture 98 of the mixed liquid tank 112 into the processing tank 123 at the first flow rate through the pipe 132a. The ozone supply device 128 generates ozone-containing gas Z which is a gaseous substance in the ozone generator 126 and supplies it to the processing tank 123 through the pipe 135. The nozzle 127a that sends out the ozone-containing gas Z is arranged at the lower part (preferably the bottom part) of the treatment tank 123, and has, for example, a tubular or flat shape. The nozzle 127a forms the ozone-containing gas Z into a plurality of fine bubbles and continuously supplies the treatment liquid P from the lower part to the upper part of the treatment tank 123. The pump 125a passes through the pipe 133 to continuously discharge the processing liquid P in the processing tank 123 to the outside of the processing tank 123 at the second flow rate. The ozone decomposing device 129 collects the ozone-containing gas Z accumulated in the upper part of the processing tank 123 via the pipe 134, decomposes ozone, makes it harmless, and releases it to the outside.

Among them, the above-mentioned oxidant treatment device 19 uses ozone as the oxidant, but other oxidants may also be used. It may also be a liquid oxidant or a solid oxidant that can be melted in a liquid even if it is not a gaseous oxidant. As the oxidant, for example, chlorine dioxide, peracetic acid, sodium hypochlorite, and hydrogen peroxide are listed.

The fourth separating device 20 separates the pulp fibers from the processing liquid (mixed liquid 99) containing pulp fibers processed in the oxidizer processing device 19 through a sieve with a plurality of openings, thereby recovering the pulp fibers, and generating and recycling Pulp fiber. For the fourth separation device 20, for example, a sieve separator is cited. Among them, the opening of the screen is not particularly limited, and examples thereof include slits, round holes, square holes, and meshes. In this case, slits are used. The size of the slit (wide width) is a size that makes it difficult for pulp fibers to pass through. The size of the slit is, for example, a width of 0.2 to 0.8 mm. In the case of a circular hole, the size of the circular hole is, for example, a diameter of 0.2 to 0.8 mmφ.

Among them, the system 1 preferably includes an ozone treatment device 22, a pH adjustment device 23, and a water storage tank 24. These devices are used to regenerate and reuse the acidic aqueous solution used in the system 1. By reusing the acidic aqueous solution, the cost of the acidic aqueous solution can be reduced. The ozone treatment device 22 uses the ozone-containing aqueous solution to sterilize the acidic aqueous solution 101 in which the super absorbent polymer and the acidic aqueous solution are separated from the super absorbent polymer and the acidic aqueous solution separated by the second separating device 17 separately. The pH adjusting device 23 adjusts the pH of the acidic aqueous solution 102 that has been sterilized with the ozone-containing aqueous solution to generate the regenerated acidic aqueous solution 103. The water storage tank 24 stores the remaining part of the acidic aqueous solution 103 regenerated.

Next, a method of recovering pulp fibers from the used absorbent article will be described. This method is a method of recovering pulp fibers (preferably even super absorbent polymers) from used absorbent articles, so that recycled pulp fibers (preferably even super absorbent polymers) are generated. Fig. 6 is a flowchart showing an example of the method of this embodiment. The method system includes: the third separation process S18, and the oxidant treatment process S19, preferably: the hole-opening process S11, the crushing process S12, the first separation process S13, the first dust removal process S14, and the second dust removal process S15 , The third dust removal process S16, the second separation process S17, and the fourth separation process S20. The following is a detailed description.

The hole-opening process S11 is performed by the bag breaking device 11. The collection bag A containing the used absorbent article is put into the solution tank V in which the acid aqueous solution B is stored, and the surface of the collection bag A which is in contact with the acid aqueous solution B is opened. The acidic aqueous solution B is designed to surround the collection bag A in such a way that when a hole is opened in the collection bag A, the dirt, fungi or odor of the used absorbent article in the collection bag A will not be released to the outside. seal. If the acid aqueous solution is immersed into the collection bag A from the hole, the gas in the collection bag A escapes to the outside of the collection bag A, the specific gravity of the collection bag A is heavier than the acid aqueous solution B, and the collection bag A is deposited in the acid aqueous solution B. In addition, the acidic aqueous solution B inactivates the super absorbent polymer in the used absorbent article in the collection bag A.

The superabsorbent polymer in the used absorbent article is inactivated and its water absorption capacity is reduced. As a result, the superabsorbent polymer is dehydrated and the particle size becomes smaller. Therefore, it is easy to handle in subsequent processes and the processing efficiency is improved. The reason for using an acidic aqueous solution, that is, an aqueous solution of an inorganic acid and an organic acid, as the inactivation aqueous solution, is based on the fact that ash does not remain on the pulp fibers compared with aqueous solutions such as lime or calcium chloride. In addition, it is easy to change the pH Adjust the degree of inactivation (the size of the particle size or specific gravity). With regard to the pH of the acidic aqueous solution, it is preferably 1.0 or more and 4.0 or less, and more preferably 1.2 or more and 2.5 or less. If the pH is too high, the water absorption capacity of the super absorbent polymer cannot be sufficiently reduced. In addition, there is a risk that the sterilization ability will decrease. If the pH is too low, there is a risk of equipment corrosion, and more alkaline chemicals must be used in the neutralization treatment of the wastewater treatment. In particular, in order to separate into pulp fibers, super absorbent polymers, and other materials, it is better that the size or specific gravity of the pulp fibers is relatively close to the size or specific gravity of the super absorbent polymer. Therefore, in terms of the pH of the acidic aqueous solution, by setting it to be 1.0 or more and 4.0 or less, the super absorbent polymer can be made smaller by inactivation, thereby making the size or specific gravity of the pulp fiber more and more water absorbent. The size or specific gravity of the sex polymers are relatively close to each other. Examples of organic acids include citric acid, tartaric acid, glycolic acid, malic acid, succinic acid, acetic acid, ascorbic acid, and the like. Hydroxycarbonate organic acids such as citric acid, tartaric acid, and gluconic acid are particularly preferred. Due to the chelating effect of citric acid, metal ions in the excrement are captured and can be removed, and due to the cleaning effect of citric acid, a higher effect of removing contaminants can be expected. On the other hand, in terms of inorganic acids, for example, sulfuric acid, hydrochloric acid, and nitric acid are listed, but from the viewpoint of not containing chlorine or cost, sulfuric acid is preferred. The pH changes according to the water temperature. Therefore, the pH in the present invention refers to the pH measured at the temperature of the aqueous solution at 20°C. The organic acid concentration of the organic acid aqueous solution is not particularly limited. If the organic acid is citric acid, it is preferably 0.5% by mass or more and 4% by mass or less. The inorganic acid concentration of the inorganic acid aqueous solution is not particularly limited, and if the inorganic acid is sulfuric acid, it is preferably 0.1% by mass or more and 0.5% by mass or less.

For example, in the bag breaking device 11 of FIG. 2, first, by rotating the stirring blade 33 around the rotating shaft (support shaft 32), a swirling flow is generated in the acid aqueous solution B, and the collecting bag A is physically and forcibly directed toward the acid aqueous solution B (Solution tank V) is introduced in the bottom direction. Next, the collection bag A moved to the bottom is opened by the bag breaking blade 41 rotating around the rotating shaft (support shaft 42), contacting the bag breaking blade 41. Among them, if the bag breaking blade 41 can move up and down in the solution tank V, even if the collection bag A is not introduced in the direction of the bottom of the acidic aqueous solution B (solution tank V) in a swirling flow, the bag breaking blade 41 also moves upward And make a hole in the collection bag A.

The crushing process S12 is executed by the crushing device 12. While containing the acidic aqueous solution B of the collection bag A that has an opening and sinking below the surface of the acidic aqueous solution B, that is, the mixed solution 91 is discharged from the solution tank V, the used absorbent article in the bag A is collected together with the collection bag A is broken together in the acidic aqueous solution B. For example, in the crushing device 12 of FIG. 2, first, the used absorbent article in the collection bag A sent out from the solution tank V together with the acidic aqueous solution B is placed in the acidic aqueous solution together with the collection bag A by the crushing unit 60 It is broken in B (the crushing project in liquid). At this time, in the crushing part 60, the rotating blades and spacers in the biaxial crusher that engage with each other and rotate inward are supplied with the mixed liquid 91, and the collection bag A is crushed together with the bag. Next, by the pump 63, the acidic aqueous solution B (mixed liquid 92) containing the crushed material obtained in the crushing part 60 (in-liquid crushing process) is drawn out from the crushing part 60 (drawing process), and is sent to the next process.

Here, in the crushing process S12, it is preferable to have a process in which the used absorbent article is crushed together with the collection bag A so that the average value of the size of the crushed material becomes 50 mm or more and 100 mm or less. In the case of absorbent articles, the imaginary length is approximately 150-1000 mm and the width is 100-1000 mm. By crushing so that the average size of the crushed material becomes 50 mm or more and 100 mm or less, the back sheet and/or surface sheet of each used absorbent article can be reliably inserted into the cut portion. In this way, in each used absorbent article, the pulp fiber can be taken out from the cut portion without remaining, so the recovery rate of the pulp fiber can be improved (the total amount of recycled pulp fiber/used used The total amount of pulp fibers of the absorbent article). If the average size is less than 50mm, materials other than pulp fiber (example: film (material of collection bag A, back sheet, etc.), non-woven fabric (surface sheet, etc.), elastomer (rubber for leak-proof wall, etc.) )) The cut is too small, and it is difficult to separate these materials from the pulp fibers in subsequent projects. As a result, foreign matter (other materials) mixed into the recycled pulp fiber increases, and the recovery rate of the pulp fiber decreases. On the other hand, if the average value of the size is greater than 100 mm, it is difficult to put the used absorbent article into the cut portion. As a result, a used absorbent article in which the pulp fiber cannot be taken out is produced, and the recovery rate of the pulp fiber is reduced.

The first separation process S13 is executed by the first separation device 13. While stirring the mixed liquid 92 containing the crushed product obtained in the crushing device 12 and the acidic aqueous solution to remove dirt from the crushed product, the mixed liquid 92 is separated into pulp fibers, super absorbent polymer, acidic aqueous solution, and others. Materials. At this time, in order to improve the cleaning effect and/or to adjust the pH, an acidic aqueous solution may be additionally added. As a result, the pulp fibers, the super absorbent polymer, and the acidic aqueous solution (partly including other materials, etc.) in the mixed liquid 92 are separated through the through holes and sent out by the first separating device 13 (mixed liquid 93). On the other hand, materials other than the pulp fiber, super absorbent polymer, and acidic aqueous solution in the mixed liquid 92 cannot pass through the through holes and remain in the first separation device 13 or are sent out through other paths. Among them, a part of other materials is not completely separated, but is sent out together with the mixed liquid 93. Here, when a washing machine is used as the first separating device 13, the size of the through hole of the washing tank functioning as a sieve is, if it is a round hole, 5mm to 20mmφ, if it is a hole of another shape, Enumerate the size that is approximately the same area as the round hole.

This method (system) is used in the crushing process (opening process S11 (bag breaking device 11) to the first separation process S13 (first separation device 13)) for crushing the used absorbent article as described above, at least Equipped with: hole-opening process S11 (bag breaking device 11), crushing process S12 (crushing device 12). Therefore, since the used absorbent article in the state of being put into the collection bag is broken in the inactivation aqueous solution together with the collection bag, at least until the beginning of the breakage, there is almost no contamination or contamination in the inactivation aqueous solution. Fungus, or a situation that produces odor. Next, when the used absorbent article is broken, even if the inactivated aqueous solution is mixed with dirt or fungus, or produces odor, it is roughly at the same time as the broken, and the inactivated aqueous solution that has mixed with dirt or fungus is together with the broken material. It is sent out from the solution tank, so dirt or fungi hardly remain in the solution tank and can be washed away. In addition, the aqueous solution may not be activated to seal off odors, so the occurrence of odors is also suppressed to a low level. Thereby, when the used absorbent article is broken, it is possible to prevent dirt, fungus flying, or odor from being released.

Among them, it is also possible to break the used absorbent article in an inactivated aqueous solution (example: acidic aqueous solution) without the collection bag, and in the gas (example: air), the used absorbent article together with the collection bag The absorbent article shattered. In this case, the hole-opening process S11 is not required, and the crushing process S12 performs crushing in the air without the inactivated aqueous solution. After that, the inactivated aqueous solution is supplied to the first separation step S13 together with the crushed material in the crushing step S12.

Among them, between the hole opening process S11 to the first separation process S13, if an acidic aqueous solution is not used as the inactivation aqueous solution, it is preferable to add the acidic aqueous solution from the first dust removal process S14, and include the supply of the first dust removal process S14 The inactivated aqueous solution of pulp fiber and super absorbent polymer is substantially formed as an acidic aqueous solution. At this time, the specific gravity and size of the super absorbent polymer can be easily adjusted by pH.

The first dust removal process S14 is executed by the first dust removal device 14. The acidic aqueous solution containing pulp fibers and superabsorbent polymer sent from the first separation device 13, that is, the mixed solution 93 is separated into pulp fibers and high-absorbent polymers by sieve while maintaining the pH within a predetermined range. Acidic aqueous solution of water-absorbing polymer, and other materials (foreign matter). As a result, the pulp fibers, superabsorbent polymer, and acidic aqueous solution (part of which include other materials, etc.) in the mixed liquid 93 are separated by a sieve, and are sent out by the first dust removal device 14 (mixed liquid 94). On the other hand, materials other than the pulp fiber, super absorbent polymer, and acidic aqueous solution in the mixed liquid 93 cannot pass through the screen and remain in the first dust removal device 14 or are sent out through other paths. Among them, a part of the other materials is not completely separated and is sent out together with the mixed liquid 94.

Among them, the acidic aqueous solution is preferably adjusted to pH at least until the first dust removal process S14, so that the specific gravity and size of the superabsorbent polymer and the specific gravity and size of each pulp fiber are different within a predetermined range. The predetermined range means, for example, a range where one of them is 0.2 to 5 times the other. At this time, the engineering department before the first dust removal process S14 can be regarded as the difference between the specific gravity and size of the pulp fiber, super absorbent polymer, and the specific gravity and size of each pulp fiber in a predetermined An inactivation process in which the acidic aqueous solution after adjusting the pH in a manner within the range is mixed to inactivate the super absorbent polymer.

In addition, in terms of the concentration after combining the pulp fiber and the super absorbent polymer in the acidic solution of the first dust removal process S14, for example, 0.1% by mass or more and 10% by mass or less, and 0.1% by mass or more and 5% by mass are listed. % Or less is better. In addition, examples of the ratio series of the pulp fiber to the super absorbent polymer in the acid solution are 50 to 90% by mass: 50 to 10% by mass.

The second dust removal process S15 is executed by the second dust removal device 15. The acidic aqueous solution containing pulp fiber and super absorbent polymer sent from the first dust removal device 14, that is, the mixed solution 94 is separated into pulp fiber and super absorbent by sieve while maintaining the pH within a predetermined range. Acidic aqueous solutions of polymers, and other materials (foreign substances). As a result, the pulp fiber, superabsorbent polymer, and acidic aqueous solution (partly including other materials, etc.) in the mixed liquid 94 are separated by a sieve, and are sent out by the second dust removal device 15 (mixed liquid 95). On the other hand, materials other than the pulp fiber, super absorbent polymer, and acidic aqueous solution in the mixed liquid 94 cannot pass through the screen and remain in the second dust removal device 15 or are sent out through other paths. Among them, a part of other materials is not completely separated and is sent out together with the mixed liquid 95. Among them, the acidic aqueous solution adjusts the pH so that the difference between the specific gravity and size of the super absorbent polymer and the specific gravity and size of each pulp fiber is within a predetermined range.

The third dust removal process S16 is executed by the third dust removal device 16. The acidic aqueous solution containing pulp fiber and super absorbent polymer sent from the second dust removal device 15, that is, the mixed liquid 95 is centrifuged in the conical frame in the opposite direction while maintaining the pH within a predetermined range, and is separated Pulp fibers, super absorbent polymers and other materials (heavier foreign matter) in the acidic aqueous solution. As a result, the pulp fiber, super absorbent polymer, and acidic aqueous solution in the mixed liquid 95 are sent out from the upper part of the third dust removal device 16 (cyclone separator) (mixed liquid 96). On the other hand, except for the pulp fiber, super absorbent polymer, and acidic aqueous solution in the mixed liquid 95, other materials that are heavy like metals are sent out from the lower part of the third dust removal device 16 (cyclone). Among them, the acidic aqueous solution adjusts the pH so that the difference between the specific gravity and size of the super absorbent polymer and the specific gravity and size of each pulp fiber is within a predetermined range.

This method (system) is used in the dust removal process (the first dust removal process S14 (first dust removal device 14) to the third dust removal process S16 (third dust removal device 16) to remove foreign materials (other materials) as described above, and at least : The second dust removal process S15 (the second dust removal device 15), the third dust removal process S16 (the third dust removal device 16)). Therefore, the pulp fiber and super absorbent polymer can be separated from the pulp fiber and super absorbent polymer, and the other materials of the used absorbent article are mainly resin materials, which can be easily separated by size (Second Dust Removal). Process S15 (the second dust removal device 15)), among other materials, materials with a high specific gravity, such as metal materials, are easily separated by specific gravity (the third dust removal process S16 (third dust removal device 16)). Then, after that, the pulp fiber and super absorbent polymer are separated from each other (Second and Third Separation Process S17, S18 (Second and Third Separation Device 17, 18), whereby the pulp fiber can be recovered from the used absorbent article And super absorbent polymer. In this case, it can reduce the processing frequency of separating pulp fiber and super absorbent polymer from other materials. That is, it can improve the processing efficiency of separating super absorbent polymer and pulp fiber.

The second separation process S17 is executed by the second separation device 17. The aforementioned acidic aqueous solution containing pulp fibers and superabsorbent polymer sent from the third dust removal device 16, namely the mixed solution 96, is separated into the pulp fibers in the acidic aqueous solution and the high content of the acidic aqueous solution by the cylindrical sieve. Water-absorbing polymer. As a result, the acidic aqueous solution containing the superabsorbent polymer passes through the cylindrical sieve, is separated by the mixed liquid 96, and is sent out from the second separation device 17. On the other hand, the acidic aqueous solution containing pulp fibers in the mixed liquid 96 cannot pass through the cylindrical sieve and is sent from the second separator 17 through another route (the mixed liquid 97). Among them, afterwards, the superabsorbent polymer can be separated by a sieve separator or the like from the separated superabsorbent polymer and the acidic aqueous solution. Therefore, the above process is the process of separating/recovering the super absorbent polymer, so it can be called the process of generating and recovering the super absorbent polymer.

The third separation process S18 is executed by the third separation device 18. The pulp fiber sent out from the second separating device 17, the superabsorbent polymer and the acidic aqueous solution that cannot be separated but remain, that is, the mixed liquid 97, are separated into the pulp fiber and superabsorbent polymer by a cylindrical screen. The solids of the compound, namely the mixture 98, and the liquid E containing the superabsorbent polymer and the acidic aqueous solution. Then, together with the separation, the super absorbent polymer in the solid is pressurized and crushed. As a result, the acidic aqueous solution containing the super absorbent polymer passes through the cylindrical sieve to be separated by the mixed liquid 97 and is sent out from the third separation device 18. On the other hand, the crushed pulp fibers of the superabsorbent polymer in the mixed liquid 97 cannot be added to the cylindrical screen, and the gap of the cover at the front end of the cylindrical screen is sent out to the outside of the third separator 18 ( Mix 98).

For example, in the third separating device 18 shown in FIG. 3, first, the mixed liquid 97 containing pulp fibers, super absorbent polymer, and acidic aqueous solution sent from the second separating device 17 is put into the cylindrical screen 81 , And reach around the screw shaft 82. With the driving device 86, the screw shaft 82 rotates, and the mixed liquid 97 around the screw shaft 82 is pressed against the side of the cylindrical screen 81 by the screw shaft 82 and the screw blade 83, and is pressed toward the cylindrical screen. The front end of 81 is transported. At this time, the superabsorbent polymer and the acidic aqueous solution pass through the side sieve of the cylindrical sieve 81, thereby being separated from the mixed liquid 97, and pulp fibers and a part of the superabsorbent polymer remain in the cylindrical sieve 81. That is, it is separated from the mixed liquid 97: the solid containing the pulp fiber and the super absorbent polymer, that is, the mixture 98, and the liquid E containing the super absorbent polymer and the acidic aqueous solution. Next, the mixture 98 is forcibly sent out from the gap G between the front end of the cylindrical screen 81 and the lid 84 that is pressurized in the opposite direction to the conveying direction of the mixture 98 while being pressurized. In the process of being conveyed and sent out while being pressurized, the super absorbent polymer in the mixture 98 is crushed. On the other hand, the liquid E is sent out from the frame 80. The pressure series of the pressing applied to the lid 84 is, for example, 0.01 MPa or more and 1 MPa or less, and preferably 0.02 MPa or more and 0.5 MPa or less. If the pressure is less than 0.02 MPa, it is difficult to crush the super absorbent polymer, and the oxidizing agent treatment time cannot be shortened too much. If the pressure is greater than 0.5 MPa, the super absorbent polymer will be crushed sufficiently, but the pulp will be damaged. The fear of fiber.

The oxidant treatment process S19 is executed by the oxidant treatment device 19. The pulp fiber and the crushed super absorbent polymer in the solid sent from the third separation device 18 are treated with an aqueous solution containing an oxidizing agent. Thereby, the super absorbent polymer undergoes oxidative decomposition and is removed from the pulp fiber. As a result, the super absorbent polymer originally attached to the pulp fibers of the mixture 98 (example: remaining on the surface of the pulp fibers) is oxidized and decomposed by an aqueous solution (treatment liquid) containing an oxidizing agent (example: ozone), and then becomes soluble The low-molecular-weight organic matter in the aqueous solution is thereby removed from the pulp fiber. Here, the state where the super-absorbent polymer undergoes oxidative decomposition and is changed into a low-molecular-weight organic substance soluble in an aqueous solution refers to a state in which the super-absorbent polymer passes through a 2 mm sieve. Thereby, impurities such as super absorbent polymers contained in the pulp fibers can be removed to produce high-purity pulp fibers, and the pulp fibers can be sterilized, bleached, and deodorized by the oxidizing agent treatment.

For example, in the oxidant treatment device 19 shown in FIG. 4, a mixture 98 containing pulp fibers (residual superabsorbent polymer) separated in the third separation step S18 is provided through a supply port provided in the upper part of the treatment tank 123 122b is supplied to the treatment liquid P. The treatment liquid P is an acidic aqueous solution (for ozone deactivation suppression and superabsorbent polymer inactivation), and its specific gravity is approximately 1. Therefore, the pulp fibers are deposited from the upper part of the treatment liquid P toward the lower part. On the other hand, the ozone-containing gas Z generated by the ozone generator 126 is mixed with the processing liquid P by the ozone mixing device 127, passes through the pipe 136, and is supplied to the processing tank 123 through the supply port 122c. The ozone-containing gas Z is continuously discharged into the processing liquid P in the state of fine bubbles (e.g., micro-bubbles or nano-bubbles) from the vicinity of the supply port 122c in the lower portion of the processing tank 123. That is, the ozone-containing gas Z rises from the lower part of the processing liquid P to the upper part. Next, in the treatment liquid P, the pulp fibers deposited from the upper part to the lower part and the ozone-containing gas Z rising from the lower part to the upper part collide with each other while advancing relative to each other. Next, the ozone-containing gas Z adheres to the surface of the pulp fiber so as to enclose the pulp fiber. At this time, the ozone in the ozone-containing gas Z reacts with the super absorbent polymer in the pulp fiber to oxidatively decompose the super absorbent polymer and dissolve in the treatment liquid P. Thereby, the super absorbent polymer on the pulp fiber is removed from the pulp fiber. Since it is a countercurrent flow, the probability of contact between the super absorbent polymer contained in the pulp fiber and the ozone-containing gas Z can be increased. Then, the pulp fiber system is deposited to the bottom of the processing tank 123, and the ozone-containing gas Z system escapes to the upper space of the processing tank 123. The ozone of the ozone-containing gas Z accumulated in the upper portion of the processing tank 123 is decomposed by the ozone decomposition device 129 and rendered harmless, and is discharged to the outside. After that, the treatment liquid P (including pulp fibers) at the bottom of the treatment tank 123 is supplied to the treatment tank 123 through the supply port 122 a provided in the upper part of the treatment tank 123 by the pump 121, through the pipe 132. Thereby, the pulp fiber system of the processing liquid P is deposited again from the upper part to the lower part of the processing liquid P, and can react with the ozone-containing gas Z that rises again from the lower part to the upper part. As shown above, the treatment liquid P containing pulp fibers treated with the ozone-containing gas Z is again supplied from the lower part (bottom) of the treatment tank 123 to the upper part of the treatment tank 123, thereby forcibly generating from the upper part of the treatment tank 123 A continuous and stable flow of fluid (including pulp fibers) towards the bottom. The probability of contact between the super absorbent polymer contained in the pulp fiber and the ozone-containing gas Z can be further improved. In addition, the pulp fiber is repeatedly treated with ozone-containing gas Z, so the super absorbent polymer contained in the pulp fiber can be almost removed, and the purity of the pulp fiber can be extremely high. If the oxidant treatment device 19 of FIG. 4 is used, the oxidant treatment process S19 is preferably performed in batch processing.

If the ozone-containing gas Z is supplied to the treatment liquid P, the ozone concentration series in the treatment liquid P is, for example, 1 to 50 mass ppm. Examples of the ozone concentration series in the ozone-containing gas Z are 40 to 200 g/m ³ . The concentration series of the pulp fibers (including the super absorbent polymer) in the treatment liquid P is, for example, 0.1 to 20% by mass. The time series during which the pulp fiber exists in the treatment tank 123 is, for example, 2 minutes to 60 minutes. The ozone-containing gas Z is delivered in the state of micro-bubbles (bubbles with a diameter of about 1 to 1000 μm) or nanobubbles (bubbles with a diameter of about 100-1000 nm). That is, micro-bubbles or nano-bubbles are fine bubbles with a large surface area per unit volume and a slow rise in the liquid, thus increasing the probability of bubbles contacting the pulp fibers. In addition, the fine air bubbles can more contact the surface of the pulp fiber. Thereby, the pulp fiber can be wrapped with fine bubbles without omission, and the contact area between the pulp fiber and the ozone-containing gas Z is further increased. In addition, because more bubbles contact the surface of the pulp, the buoyancy of the bubbles reduces the deposition rate of the pulp fibers containing the superabsorbent polymer and increases the contact time between the pulp fibers and the ozone-containing gas Z. By these, the super absorbent polymer contained in the pulp fiber can be oxidized and decomposed more reliably and removed from the pulp fiber.

In the oxidant treatment device 19 shown in FIG. 5, the pulp fiber (residual superabsorbent polymer) separated in the third separation step S18 is mixed with the acidic aqueous solution to become the treatment liquid Pa. The processing liquid Pa is supplied to the mixed liquid tank 112 through the pipe 131 and stored. Next, the processing liquid Pa in the mixed liquid tank 112 is continuously supplied to the processing tank 123 at the first flow rate through the pipe 132a by the flow control of the pump 121a. Thereby, the pulp fiber is supplied to the processing liquid P through the supply port 122 provided in the upper part of the processing tank 123. As shown in FIG. The treatment liquid P is an acidic aqueous solution, and its specific gravity is approximately 1. Therefore, the pulp fibers are deposited from the upper part of the treatment liquid P toward the lower part. On the other hand, the ozone-containing gas Z generated by the ozone generator 126 is supplied to the processing tank 123 through the pipe 135, and is in the state of fine bubbles by the nozzle 127a of the processing tank 123 (example: micro-bubble or nano-bubble) ) Is continuously discharged into the treatment liquid P. That is, the ozone-containing gas Z rises from the lower part of the processing liquid P to the upper part. Next, in the treatment liquid P, the pulp fibers deposited from the upper part to the lower part and the ozone-containing gas Z rising from the lower part to the upper part collide with each other while advancing oppositely. Next, the ozone-containing gas Z adheres to the surface of the pulp fiber so as to enclose the pulp fiber. At this time, the ozone in the ozone-containing gas Z reacts with the super absorbent polymer in the pulp fiber to oxidatively decompose the super absorbent polymer and dissolve in the treatment liquid P. Thereby, the super absorbent polymer on the pulp fiber is removed from the pulp fiber. Since it is a countercurrent flow, the probability of contact between the super absorbent polymer contained in the pulp fiber and the ozone-containing gas Z can be increased. Then, the pulp fiber system is deposited on the bottom of the processing tank 123, and the ozone-containing gas Z system escapes toward the upper space of the processing tank 123. After that, the treatment liquid P (including pulp fiber) at the bottom of the treatment tank 123 is controlled by the flow rate of the pump 125a, passes through the pipe 133, and is continuously discharged from the discharge port 124 of the treatment tank 123 to the outside of the treatment tank 123 at the second flow rate. . The ozone of the ozone-containing gas Z accumulated in the upper portion of the processing tank 123 is decomposed by the ozone decomposition device 129 and rendered harmless, and is discharged to the outside. As shown above, the treatment liquid Pa is continuously supplied to the treatment tank 123 at the first flow rate from the upper part of the treatment tank 123, and the treatment liquid P is continuously discharged to the treatment tank 123 at the second flow rate from the lower part (bottom) of the treatment tank 123. Outside. Thereby, a continuous and stable flow of fluid (including pulp fibers) from the upper part to the lower part can be forcibly generated in the treatment tank 123. It can increase the probability of contact between the super absorbent polymer contained in the pulp fiber and the ozone-containing gas Z. If the oxidant treatment device 19 of FIG. 5 is used, the oxidant treatment step S19 is preferably performed by continuous treatment.

However, if the oxidizing agent is ozone, by forming the treatment liquid into an acidic aqueous solution, the deactivation of ozone can be suppressed, and the effect of ozone can be improved (oxidative decomposition of super absorbent polymer, sterilization, bleaching, and deodorization). In addition, in addition to inactivating the super absorbent polymer, if an acidic aqueous solution is used in the crushing treatment or dust removal treatment, due to the continuity between the treatments, there will be no difference in the aqueous solution between the treatments. Any unfavorable situation can be dealt with in a stable and reliable manner. In addition, from the viewpoint of reducing the impact on the operator or equipment caused by the acid, the organic acid in the acidic aqueous solution is preferred, and the citric acid is also preferred from the viewpoint of metal removal.

Here, the first flow rate and the second flow rate are preferably the same. By making the first flow rate and the second flow rate the same, the amount of the treatment liquid P in the treatment tank 123 can be kept constant, and stable and continuous treatment can be performed. Among them, the first flow rate and the second flow rate do not necessarily have to be completely the same all the time, and they may be approximately the same (with an error of 5% or less) on average over time.

The fourth separation process S20 is performed by the fourth separation device 20. The processing liquid containing pulp fibers processed in the oxidant processing device 19, that is, the mixed liquid 99 passes through a sieve with a plurality of openings, and the mixed liquid 99 is Separate pulp fiber and treatment liquid. As a result, the processing liquid 104 is separated by the mixed liquid 99 through the sieve, and is sent out by the fourth separation device 20. The separated treatment liquid 104, that is, the oxidant treatment liquid can also be sent back to the oxidant treatment device 19 for reuse. The cost of the oxidant treatment liquid can be reduced. On the other hand, the pulp fibers in the mixed liquid 99 cannot pass through the screen and remain in the fourth separator 20 or are sent out through other paths. The above process is a process of separating/recycling pulp fibers, so it can be called a process of generating recycled pulp fibers.

Among them, the specific gravity of the super absorbent polymer is measured by the pycnometer method of JIS K 0061 for the density and specific gravity of chemical products. As a result, the specific gravity of the water-absorbing polymer before water absorption was 1.32 g/ml. The specific gravity when the citric acid aqueous solution (pH 2) is inactivated is 1.04 g/ml, and the specific gravity when the citric acid aqueous solution (pH 4) is inactivated is 1.01 g/ml. On the other hand, it is difficult to measure the size of the super absorbent polymer (after water absorption). Therefore, assuming that the super absorbent polymer is a ball, the size (diameter) is calculated as shown below. That is, the average diameter of the super absorbent polymer before water absorption is set to 200 μm, and the amount of water in the aqueous solution absorbed by the super absorbent polymer is calculated by volume expansion to estimate the water absorption of the super absorbent polymer The size (diameter) of the back. Here, the volume expansion calculation system is performed as follows. First, the amount of water absorbed by the super absorbent polymer (average per grain) is measured. Next, the volume of water corresponding to this amount of water is assumed to be the volume V of the super absorbent polymer after water absorption, and the radius r of the super absorbent polymer after water absorption is obtained ^{from V=4/3πr 3.} Next, the diameter twice the radius r is set to the size of the super absorbent polymer (after water absorption). As a result, the gel diameter when inactivated with a citric acid aqueous solution (pH 2) was about 420 μm, and the gel diameter when inactivated with a citric acid aqueous solution (pH 4) was about 540 μm.

Here, the ratio of the pulp fiber and the super absorbent polymer in the acidic aqueous solution is measured as follows. First, a part of the acidic aqueous solution was taken as a sample, and the sample was put in a 200-mesh filter to measure the sample weight W0. Next, the sample on the filter was suspended for 5 minutes to remove water, and the absolute drying was performed by a predetermined absolute drying method (heating at 120°C for 10 minutes and drying), and the absolute of the obtained absolute dried product was measured. Dry weight W1. Next, the absolutely dried product is immersed in an ozone-containing aqueous solution, and the resultant is absolutely dried by the above-mentioned absolute drying method to form a pulp fiber, and the absolute dry weight W2 is measured. Next, the weight obtained by subtracting the absolute dry weight W2 from the absolute dry weight W1 is taken as the weight of the super absorbent polymer, and the ratio of the pulp fiber and the super absorbent polymer in the acidic aqueous solution is calculated by the following formula. That is, it is formed as (proportion of pulp fiber)=(absolute dry weight W2)/(sample weight W0), and is formed as (proportion of super absorbent polymer)=(absolute dry weight W1-absolute dry weight W2)/ (Sample weight W0). In terms of weight ratio, the solid weight of the dirt is extremely small, so it can be ignored.

However, the ozone concentration in the aqueous solution is measured as follows. First, in a 100 mL graduated cylinder into which about 0.15 g of potassium iodide and 5 mL of a 10% citric acid solution have been placed, 85 mL of an ozone-dissolved aqueous solution is placed. After the reaction, it was transferred to a 200 mL Erlenmeyer flask. After adding the starch solution to this place to make it purple, it was titrated while stirring with 0.01 mol/L sodium thiosulfate until it became colorless. From the titration value, the following formula is used to calculate the concentration of ozone in the aqueous solution. The concentration of ozone in the aqueous solution (mass ppm) = 0.01mol/L sodium thiosulfate (mL) × 0.24 × 0.85 (mL) required for titration

Among them, the method preferably includes ozone treatment process S22 and pH adjustment process S23. These processes are processes for regenerating and reusing the acidic aqueous solution used in the method. By reusing the acidic aqueous solution, the cost of the acidic aqueous solution can be reduced. In the ozone treatment process S22, the super absorbent polymer separated in the second separation process S17 and the acid aqueous solution 101 after the super absorbent polymer is separately separated from the acid aqueous solution are sterilized with an ozone-containing aqueous solution. The pH adjustment process S23 adjusts the pH of the acidic aqueous solution sterilized with the ozone-containing aqueous solution to generate the regenerated acidic aqueous solution 103. The acidic aqueous solution 103 is supplied to the crushing device 11, for example. Or, if there is no hole-opening process S11, and the inactivation aqueous solution is not used for crushing in the crushing process S12, it is supplied to the 1st separation process S13. Or, if necessary, the acidic aqueous solution can be supplied to other required processes (devices). The remainder of the acidic aqueous solution 103 is stored in the water storage tank 24.

The method of recovering pulp fibers from the used absorbent articles containing pulp fibers and superabsorbent polymers mentioned above is in the recycling process of recycled pulp fibers (Second Separation Process S17 (Second Separation Device 17) to Fourth Separation Process S20 (fourth separation device 20)) includes at least: solid-liquid separation process (solid-liquid separation device), that is, the third separation process S18 (third separation device 18); and oxidant treatment process S19 (oxidant treatment) Device 19). Next, in the third separation process S18 (third separation device 18), the water-absorbent gel-like (lumpy or roughly spherical) superabsorbent polymer remaining in the pulp fibers is crushed to make high The thickness of the water-absorbing polymer becomes thin, and it is formed into a flat shape or a finely divided shape. The crushing system exemplifies the crushing of a gel-like super absorbent polymer under a pressure higher than the gel strength. That is, this method or system can expand the surface area of the superabsorbent polymer by crushing the roughly spherical or massive superabsorbent polymer, and can increase the inner surface of the superabsorbent polymer. Partially exposed on exposed parts such as the front side. Therefore, in the oxidant treatment process S19 (oxidant treatment device 19), if it is a block or roughly spherical super absorbent polymer, the inner part of the super absorbent polymer that is difficult to come into contact with the oxidant can be brought into contact with the oxidant. And so on, can increase the contact area of the super absorbent polymer with the oxidant. Thereby, the oxidative decomposition of the super absorbent polymer can be progressed more efficiently, and the time for the oxidizing agent treatment can be shortened. Therefore, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

In the preferred aspect of the embodiment, the third separation process S18 (third separation device 18) may also include: an inactivated aqueous solution containing pulp fibers and super absorbent polymers (example: acidic aqueous solution) A crushing process (screw press dehydrator) in which the superabsorbent polymer remaining in the pulp fiber is crushed by the pressurized dehydration method. This method or system crushes the superabsorbent polymer remaining in the pulp fiber by the pressurized dehydration method, so that the solid-liquid separation and the superabsorbent polymer on the pulp fiber can be efficiently and reliably performed at the same time Crushed. That is, the surface area of the super absorbent polymer on the pulp fiber can be expanded efficiently and surely. Thereby, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

In the preferred aspect of the embodiment, the pressure during the pressurization of the pressurized dehydration method in the crushing process (screw press dehydrator) of the third separation process S18 may be 0.02 MPa or more and 0.5 Pa. the following. In this method or system, the pressure during pressurization of the pressurized dehydration method is set to 0.02 MPa or more and 0.5 Pa or less. Therefore, the pulp fiber is not damaged, and the super absorbent polymer remaining in the pulp fiber can be sufficiently crushed, so the surface area of the super absorbent polymer can be sufficiently expanded. Thereby, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved. However, if the pressure is set to less than 0.02MPa, the super absorbent polymer cannot be crushed sufficiently, and the oxidant treatment time cannot be shortened. If the pressure is greater than 0.5 MPa, the super absorbent polymer can be crushed sufficiently. , But there is a risk of damaging the pulp fibers.

In the preferred aspect of the embodiment, before the third separation process S18 (third separation device 18), it is additionally equipped with: an inactivated aqueous solution containing pulp fibers and superabsorbent polymer The process of separating a part of the superabsorbent polymer and the inactivated aqueous solution, that is, the second separation process S17 (the cylindrical sieve dehydrator of the second separator 17). This method or system is a cylindrical screen dehydrator equipped with a second separation step S17 (second separation device 17) before the third separation step S18 (third separation device 18). Therefore, this method/system can reduce the proportion of super absorbent polymer in the materials (pulp fiber, super absorbent polymer, and inactivated aqueous solution) supplied to the third separation process S18 (third separation device 18) The suppression is low. Thereby, in the third separation process S18 (third separation device 18), the super absorbent polymer adhering to the pulp fiber can be crushed more efficiently, and the removal of the super absorbent polymer from the pulp fiber can be improved. Processing efficiency.

In a preferred aspect of the embodiment, the ratio of the super absorbent polymer in the inactivated aqueous solution supplied to the third separation step S18 (third separation device 18) may be 50% or less. In this method or system, in the third separation process S18 (third separation device 18), the ratio of the superabsorbent polymer in the inactivated aqueous solution to be separated is 50% or less. Thereby, since there is no need to crush an excessive amount of super absorbent polymer, the super absorbent polymer can be crushed more reliably and efficiently. Thereby, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

In the preferred aspect of the embodiment, before the third separation process S18 (third separation device 18), it is also possible to additionally include a process for crushing the used absorbent article in an inactivated aqueous solution. (Including S12); and the process of separating the inactivated aqueous solution containing pulp fibers and superabsorbent polymer from the inactivated aqueous solution containing the crushed product obtained in the process for crushing (including S12) (including S13, It preferably contains S14 to S16). This method or system generates pulp which is supplied in the third separation process S18 (third separation device 18) and contains the used absorbent articles separated by the crushing process and the cleaning separation process. An inactivated aqueous solution of fiber and super absorbent polymer. By using the process of crushing and the process of separating, it is possible to prevent foreign matter from being mixed in the inactivated aqueous solution (materials other than pulp fibers and super absorbent polymers of disposable absorbent articles (example: film, non-woven fabric) , Elastomers, etc.). Thereby, the super absorbent polymer can be crushed more accurately without being hindered by foreign matter. As a result, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

In the preferred aspect of the embodiment, the inactivated aqueous solution may also be an acidic aqueous solution. In this method or system, since the inactivation aqueous solution is an acidic aqueous solution, the superabsorbent polymer in the used absorbent article can be surely dehydrated and formed into a predetermined size (example: particle size) or less. Thereby, in the third separation process S18 (third separation device 18), the super absorbent polymer can be crushed easily while performing solid-liquid separation. As a result, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved.

In a preferred aspect of the embodiment, the acidic aqueous solution may also have a pH of 2.5 or less. In this method or system, the acidic aqueous solution has a pH of 2.5 or less, so that the superabsorbent polymer in the used absorbent article can be dehydrated more reliably and be formed to a predetermined size (example: particle size) or less. Thereby, in the third separation process S18 (third separation device 18), the super absorbent polymer can be crushed more easily while performing solid-liquid separation. As a result, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved. In addition, since the super absorbent polymer is formed into a predetermined size or less in the state of a gel, the super absorbent polymer can be easily crushed.

In the preferred aspect of the embodiment, the acidic aqueous solution may also contain citric acid. In the present method or system, since the acidic aqueous solution contains citric acid (example: concentration 0.5-2.0% by mass), the superabsorbent polymer in the used absorbent article can be surely dehydrated and formed into a predetermined particle size or less. Thereby, in the third separation process S18 (third separation device 18), the super absorbent polymer can be crushed easily while performing solid-liquid separation. As a result, the treatment efficiency of removing the super absorbent polymer from the pulp fiber can be improved. [Example]

Hereinafter, an example of a method of recovering pulp fibers from the above-mentioned used absorbent article will be described.

In this embodiment, the third separation step S18 and the oxidizing agent treatment step S19 of the above-mentioned method are performed on the absorbent article after pulverization and removal of materials other than pulp fibers and superabsorbent polymers. Next, the relationship between the pressure applied during the pressurization of the third separation step S18 and the treatment time of the oxidant treatment in the oxidant treatment step S19 was investigated. Specifically, as an absorbent article, a mixed liquid 97 obtained by treating a plurality of disposable diapers (unused) for adults in the crushing process S12 to the second separating process S17 is used. In the third separation step S18, the pressure (pressure applied to the lid) applied during pressurization by the pressurization dehydration method is changed to 0 to 3.3 kgf/cm ² (0 to 0.32 MPa). At this time, the time during which the super absorbent polymer was not detected from the pulp fiber in the oxidizing agent treatment process S19 was measured as the treatment time. The treatment time is in the oxidizing agent treatment process S19. A predetermined amount of pulp fibers are taken out at regular intervals to detect whether the super absorbent polymer is attached to the pulp fibers, and set the time when the super absorbent polymer is not detected. Is the processing time.

In addition, whether or not the super absorbent polymer adheres to the pulp fibers is measured as follows. After taking out 10 g of the pulp fiber and removing the moisture, the fiber was unwound while irradiating with light, and the adhesion of the residual polymer was visually confirmed with a magnifying glass with a magnification of 20 times. If there is residual polymer, the light is reflected and emits light, so it can be easily found.

The result of investigating the relationship between the pressure applied during pressurization and the treatment time of the oxidant treatment is shown in FIG. 7. Fig. 7 is a graph showing the relationship between the pressure applied during pressurization and the treatment time of the oxidant treatment. The horizontal axis indicates the applied pressure (kgf/cm ² ), and the vertical axis indicates the processing time (minutes). As shown in the figure, it is found that ^{the treatment time is 40 minutes when the applied pressure is 0kgf/cm 2} as the standard. If the applied pressure is small, the reduction effect of the treatment time is small, but the greater the applied pressure, the treatment time The greater the reduction effect. In addition, it was also found that above a certain pressure, the treatment time reduction effect was saturated. Therefore, from the viewpoint of reducing the processing time, the pressure is preferably 0.2 kgf/cm ² (0.02 MPa) or more. In addition, from the viewpoint of saturation of the reduction effect or the reliability of the reduction effect, the pressure is preferably 5 kgf/cm ² (0.5 MPa) or less. The pressure is more preferably 0.5kgf/cm ² (0.05MPa) or more and 3kgf/cm ² (0.3MPa).

The above-mentioned embodiment describes the case where the constituent member of the back sheet is formed as a film, and the constituent member of the front sheet is formed as a non-woven fabric. However, the embodiment in which the constituent members of the back sheet are formed as a non-woven fabric and the constituent members of the front sheet are formed as a film, or when the constituent members of both the back sheet and the front sheet are formed as films, can also be implemented as described above. The same method can achieve the same effect.

The absorbent article of the present invention is not limited to the above-mentioned respective embodiments, and can be combined or changed appropriately without departing from the purpose and spirit of the present invention.

1‧‧‧System 11‧‧‧Bag breaking device 12‧‧‧Crushing device 13‧‧‧The first separation device 14‧‧‧The first dust removal device 15‧‧‧The second dust removal device 16‧‧‧The third dust removal device 17‧‧‧Second separation device 18‧‧‧Separation device No. 3 19‧‧‧Oxidant treatment device 20‧‧‧Separation device No. 4 22‧‧‧Ozone treatment device 23‧‧‧pH adjustment device 24‧‧‧Water storage tank 30‧‧‧Delivery Department 31‧‧‧Drive device 32‧‧‧Support axis (rotation axis) 33‧‧‧Mixing blade 40‧‧‧Broken Bag Department 41‧‧‧Bag-Break Blade 42‧‧‧Support axis (rotation axis) 43‧‧‧Drive device 50‧‧‧Opening part 60‧‧‧Crushing Department 61‧‧‧Piping 62‧‧‧Piping 63‧‧‧Pump 80‧‧‧Frame 81‧‧‧Cylinder screen 82‧‧‧Spiral shaft 83‧‧‧Spiral blade 84‧‧‧Cover body 85‧‧‧Pressure regulator 86‧‧‧Drive 91‧‧‧Mixed liquid 92‧‧‧Mixed liquid 93‧‧‧Mixed liquid 94‧‧‧Mixed liquid 95‧‧‧Mixed liquid 96‧‧‧Mixed liquid 97‧‧‧Mixed liquid 98‧‧‧Mixture 99‧‧‧Mixed liquid 101‧‧‧Acid aqueous solution 102‧‧‧Acid aqueous solution 103‧‧‧Acid aqueous solution 104‧‧‧Treatment liquid 110‧‧‧Mixed liquid storage department 112‧‧‧Mixed liquid tank 113‧‧‧Mixer 120‧‧‧Oxidant Treatment Department 121‧‧‧Pump 121a‧‧‧Pump 122‧‧‧Supply Port 122a‧‧‧Supply Port 122b‧‧‧Supply Port 122c‧‧‧Supply Port 123‧‧‧Processing tank 124a‧‧‧Exit 124b‧‧‧Exit 125‧‧‧Pump 125a‧‧‧Pump 126‧‧‧Ozone generator 127‧‧‧Ozone mixing device 127a‧‧‧Nozzle 128‧‧‧Ozone supply device 129‧‧‧Ozone Decomposition Device 131‧‧‧Piping 132‧‧‧Piping 132a‧‧‧Piping 133‧‧‧Piping 134‧‧‧Piping 135‧‧‧Piping 136‧‧‧Piping A‧‧‧Collection bag B‧‧‧Acid aqueous solution E‧‧‧Liquid G‧‧‧Gap P‧‧‧Treatment fluid Pa‧‧‧treatment liquid V‧‧‧Solution tank Z‧‧‧Ozone-containing gas S11‧‧‧Hole-opening project S12‧‧‧Crushing Project S13‧‧‧Separation Project No. 1 S14‧‧‧The first dust removal project S15‧‧‧Second Dust Removal Project S16‧‧‧The third dust removal project S17‧‧‧Secondary Separation Project S18‧‧‧Separation Project No. 3 S19‧‧‧Oxidant treatment project S20‧‧‧Separation Project No. 4 S22‧‧‧Ozone Treatment Project S23‧‧‧pH adjustment project

Fig. 1 is a block diagram showing an example of the system of the embodiment. Fig. 2 is a schematic diagram showing a configuration example of the bag breaking device and the crushing device of Fig. 1. Fig. 3 is a schematic diagram showing a configuration example of the third separation device of Fig. 1. Fig. 4 is a schematic diagram showing a configuration example of the oxidant treatment device of Fig. 1. Fig. 5 is a partially enlarged view showing another configuration example of the oxidant treatment device of Fig. 1. Fig. 6 is a flowchart showing an example of the method of the embodiment. Fig. 7 is a graph showing the relationship between the pressure in the third separation process and the processing time.

S11‧‧‧Hole-opening project

S12‧‧‧Crushing Project

S13‧‧‧Separation Project No. 1

S14‧‧‧The first dust removal project

S15‧‧‧Second Dust Removal Project

S16‧‧‧The third dust removal project

S17‧‧‧Secondary Separation Project

S18‧‧‧Separation Project No. 3

S19‧‧‧Oxidant treatment project

S20‧‧‧Separation Project No. 4

S22‧‧‧Ozone Treatment Project

S23‧‧‧pH adjustment project

Claims (13)

A method for recovering pulp fibers from used absorbent articles, which is a method for recovering pulp fibers from used absorbent articles containing pulp fibers and superabsorbent polymers. The method includes: solid-liquid separation process, It is to separate the inactivated aqueous solution containing the pulp fiber and the super absorbent polymer separated from the used absorbent article into the solid containing the pulp fiber and the super absorbent polymer, and the solid containing the high absorbent polymer. The liquid of the water-absorbent polymer and the aforementioned inactivated aqueous solution, while crushing the aforementioned super-absorbent polymer contained in the aforementioned solid; and the oxidizing agent treatment process, which is the process of removing the aforementioned pulp fibers and the quilt contained in the aforementioned solid after separation. The crushed superabsorbent polymer is treated with an aqueous solution containing an oxidizing agent, and the solid-liquid separation process includes: a crushing process, which combines the inactivated aqueous solution containing the pulp fiber and the superabsorbent polymer , The pressurized dehydration method is used to process, the super absorbent polymer remaining in the pulp fiber is crushed, and the pressurized pressure of the pressurized dehydration method in the crushing process is 0.02 MPa or more, 0.2 Below MPa. Such as the method of claim 1, wherein, before the solid-liquid separation process, it is additionally provided with: from the inactivated aqueous solution containing the pulp fiber and the super absorbent polymer, the super absorbent polymer The process of separating a part of the compound and the aforementioned inactivated aqueous solution. Such as the method of item 1 or item 2 of the scope of patent application, wherein the ratio of the super absorbent polymer in the inactivated aqueous solution supplied in the solid-liquid separation process is 50% or less. For example, the method of item 1 of the scope of patent application, which, before the solid-liquid separation process, is additionally equipped with: the process of crushing the used absorbent article in an inactivated aqueous solution; and the process of crushing by the inclusion in the foregoing The process of separating the inactivated aqueous solution of the crushed material obtained in the process of separating the inactivated aqueous solution containing the pulp fiber and the super absorbent polymer. Such as the method of item 1 in the scope of the patent application, wherein the aforementioned inactivation aqueous solution is an acidic aqueous solution. Such as the method of item 5 of the scope of patent application, wherein the aforementioned acidic aqueous solution has a pH of 2.5 or less. For example, the method of item 5 or item 6 of the scope of patent application, wherein the aforementioned acidic aqueous solution contains citric acid. A system that recovers pulp fibers from used absorbent articles, It is a system that recovers pulp fibers from used absorbent articles containing pulp fibers and superabsorbent polymers. The system is equipped with a solid-liquid separation device that separates the used absorbent articles. The pulp fiber and the inactivated aqueous solution of the super absorbent polymer are separated into a solid containing the pulp fiber and the super absorbent polymer, and a liquid containing the super absorbent polymer and the inactivated aqueous solution. Crushing the aforementioned super absorbent polymer contained in the aforementioned solid; and an oxidizing agent treatment device for separating the aforementioned pulp fiber contained in the aforementioned solid and the crushed aforementioned super absorbent polymer into a substance containing an oxidizing agent The aqueous solution is processed, and the solid-liquid separation device includes: a screw press dehydrator, which treats the inactivated aqueous solution containing the pulp fiber and the super absorbent polymer by a pressurized dehydration method to remove the remaining The superabsorbent polymer of the pulp fiber is crushed, and the pressure during the pressurization of the pressurized dehydration method in the screw press dehydrator is 0.02 MPa or more and 0.2 MPa or less. Such as the system of item 8 of the scope of patent application, which is additionally equipped with: a cylindrical screen type dehydrator, which is inactivated by the aforementioned pulp fiber and the aforementioned super absorbent polymer before the aforementioned solid-liquid separation process The aqueous solution separates a part of the aforementioned super absorbent polymer and the aforementioned inactivated aqueous solution. For example, in the system of item 8 or item 9 of the scope of patent application, the ratio of the super absorbent polymer in the inactivated aqueous solution supplied to the solid-liquid separator is 50% or less. Such as the system of item 8 of the scope of patent application, wherein the aforementioned inactivated aqueous solution is an acidic aqueous solution. For example, the system of item 11 in the scope of patent application, wherein the aforementioned acidic aqueous solution has a pH of 2.5 or less. For example, the system of item 11 or item 12 of the scope of patent application, wherein the aforementioned acidic aqueous solution contains citric acid.

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