Method and system for recycling pulp fibers from used absorbent articles

Abstract

The present invention relates to a method and a system for recovering pulp fibers from used absorbent articles. A method for recovering pulp fibers from used absorbent articles, wherein the method comprises: a crushing process (S12) in which a collection bag (A) enclosing a used absorbent article is put into a container (65), the collection bag in the container is transferred to a crushing device (12) communicating with the container, and the used absorbent article in the collection bag is crushed together with the collection bag in a deactivation aqueous solution by the crushing device; and a separation process (S13) in which pulp fibers, a superabsorbent polymer, and the deactivation aqueous solution are separated from the crushed matter and the deactivation aqueous solution obtained from the crushing process.

Description

[0001] This application is a divisional application of application No. 201880068667.1, filed on July 26, 2018, entitled "Method and system for recovering pulp fibers from used absorbent articles". TECHNICAL FIELD

[0002] The present invention relates to a method and system for recovering pulp fibers from used absorbent articles. BACKGROUND

[0003] A method for recovering pulp fibers from used disposable diapers and the like absorbent articles is known. In this method, when processing used absorbent articles, it is important to improve hygiene management by improving the recovery rate of pulp fibers, processing efficiency, and the like, to suppress costs, reduce the scattering of dirt of disposable diapers, and the like. Therefore, sometimes a collection bag in which a plurality of used absorbent articles are enclosed is directly processed. By directly processing the collection bag, it is possible to reduce the work of taking out the used absorbent articles from the collection bag and the like (improve processing efficiency), and it is possible to make it difficult for dirt and bacteria attached to the used absorbent articles to come into contact with the workers (improve hygiene management).

[0004] As such a method, for example, a used paper diaper crushing and separating recovery device is disclosed in Non-Patent Literature 1. The device includes a separation tank, a sieve, a stirrer, a crushing member, a pulp class discharge member, and a plastic class discharge member. The separation tank is used to put the used paper diapers put into a collection body (bag) together with the collection body, and to supply water, a polymer separating agent, and a sterilization and fungicide. The sieve divides the separation tank into upper and lower chambers. The stirrer is provided in the upper chamber of the separation tank and stirs the processing materials (collection bag, used paper diapers, water, various agents, and the like). The crushing member is provided in the upper chamber of the separation tank and can crush the collection body and the used paper diapers. The pulp class discharge member is provided in communication with the lower chamber of the separation tank and is used to discharge the pulp class that has passed through the sieve. The plastic class discharge member is provided in communication with the upper chamber of the separation tank and discharges the plastic class that cannot pass through the sieve in a natural flow. According to Non-Patent Literature 1, in the related art, a crushing device is required in addition to the separation and recovery device, and since only the paper diapers in a state of having excrement attached thereto are crushed at the time of crushing processing, the hygiene burden is large, but the device can eliminate these cost and hygiene management problems.

[0005] Prior Art Documents

[0006] Non-Patent Literature

[0007] Non-Patent Literature 1: Japanese Utility Model Registration No. 3139358 SUMMARY

[0008] Problem to be Solved by the Invention

[0009] The device of Non-Patent Literature 1 integrates a breaking device and a separating device to form one device, tears the collection bag and breaks the used paper diaper in the collection bag in water in the separating tank using the same breaking member while stirring the water in the separating tank. Therefore, the water becomes a state in which not only the broken used paper diaper but also dirt and bacteria of the used paper diaper are mixed, and it can cause the dirt and bacteria to be scattered from the water surface to the outside, or odor to be released accompanying the dirt. In this case, depending on the situation, it can also be considered that the operator of the device directly or indirectly comes into contact with the dirt and bacteria, or is exposed to the odor during the handling and the maintenance. A technique is desired which suppresses the cost and hygienically and safely breaks the used absorbent article when pulp fibers of the used absorbent article put into the collection bag are recovered.

[0010] An object of the present application is to provide a method and a system which can suppress the cost and hygienically and safely break a used absorbent article when pulp fibers of the used absorbent article put into a collection bag are recovered.

[0011] Means for Solving the Problem

[0012] A method of recovering pulp fibers of a used absorbent article containing pulp fibers and a superabsorbent polymer according to the present application is as follows. (1) A method of recovering pulp fibers of a used absorbent article containing pulp fibers and a superabsorbent polymer, wherein the method includes: a receiving process in which a collection bag in which a used absorbent article is enclosed is put into a container; a breaking process in which the collection bag in the container is transferred to a breaking device communicating with the container while the used absorbent article in the collection bag is broken together with the collection bag in a sterilizing aqueous solution using the breaking device; and a separating process in which pulp fibers, a superabsorbent polymer, and the sterilizing aqueous solution are separated from broken matters and the sterilizing aqueous solution obtained in the breaking process using a separating device.

[0013] In the present method, at least after the collection bag is received in the container, the collection bag is transferred to a crushing device that is independently provided with respect to the container, and in the crushing device, the high-absorbency polymer of the used absorbent article in the collection bag is inactivated in the inactivating aqueous solution, and the used absorbent article is crushed together with the collection bag. That is, when the used absorbent article is crushed, the crushing is performed in the inactivating aqueous solution in the crushing device that is independent with respect to the container, and after the crushing, the inactivating aqueous solution and the crushed matter are transferred to the separation device. Therefore, even if the inactivating aqueous solution is mixed with dirt, bacteria, or odor is generated, the inactivating aqueous solution mixed with the dirt, bacteria, or the crushed matter hardly reaches the container. Thus, the crushing can be performed in the container with hardly any dirt, bacteria remaining. Further, the odor can be sealed with the inactivating aqueous solution, and thus the generation of odor can also be suppressed to be low. In particular, if the crushing is performed in the inactivating aqueous solution, the basic volatile components derived from the excrement such as urine do not volatilize but remain in the inactivating aqueous solution, and thus the generation of odor caused by the basic gas such as ammonia can be suppressed. Thus, when the used absorbent article is crushed, the scattering of dirt, bacteria, or the release of odor accompanying the dirt can be suppressed. That is, the used absorbent article can be crushed hygienically and safely, and the cost of the sanitary management of the operation and maintenance can be suppressed.

[0014] The present method can also be (2) the method according to the above (1), wherein the receiving step includes a hole opening step in which the collection bag is put into a solution tank that is the container in which the inactivating aqueous solution is accumulated, and a hole is opened on a surface of the collection bag that contacts the inactivating aqueous solution, and the crushing step includes a step in which the collection bag in which the hole is opened and sinks below the water surface of the inactivating aqueous solution is transferred from the solution tank to the crushing device together with the inactivating aqueous solution, and the used absorbent article in the collection bag is crushed together with the collection bag in the inactivating aqueous solution.

[0015] In the present method, at least by the step of opening the hole in the collecting bag, the inactivated aqueous solution is introduced from the hole into the collecting bag, the inactivated aqueous solution is used to inactivate the superabsorbent polymer contained in the used absorbent article, and the collecting bag is substantially sunk below the water surface of the inactivated aqueous solution. Thus, the collecting bag sunk below the water surface of the inactivated aqueous solution can be transferred from the solution tank together with the inactivated aqueous solution while the used absorbent article is broken together with the collecting bag in the inactivated aqueous solution. Therefore, before the breaking is started, there is almost no possibility that dirt, bacteria, or odor is mixed in the inactivated aqueous solution. Also, when the used absorbent article is broken, even if dirt, bacteria, or odor is mixed in the inactivated aqueous solution, since the inactivated aqueous solution mixed with the dirt and the bacteria is sent out from the solution tank together with the broken product at substantially the same time as the breaking, it is possible to flow away without leaving the dirt and the bacteria in the solution tank. In addition, it is possible to seal the odor with the inactivated aqueous solution, and thus it is possible to suppress the generation of odor as well. Thus, when the used absorbent article is broken, it is possible to suppress the scattering of dirt, bacteria, or odor generated along with the dirt.

[0016] The present method can also be (3) the method according to the above (2), wherein the step of opening the hole in the collecting bag of the opening step and the step of breaking the used absorbent article together with the collecting bag of the breaking step are performed at different positions.

[0017] In the present method, the step of opening the hole in the collecting bag and the step of breaking the used absorbent article together with the collecting bag are performed at different (distinct) positions. Therefore, after the inactivated aqueous solution is introduced from the hole into the collecting bag and the collecting bag is reliably sunk below the water surface of the inactivated aqueous solution, the breaking can be performed at different positions. Thus, at the time of breaking, it is possible to suppress the situation that a part of the collecting bag is exposed on the water surface of the inactivated aqueous solution, the opening (crack) of the hole is exposed on the water surface of the inactivated aqueous solution, and dirt, bacteria of the used diaper, or odor generated along with the dirt is scattered or released.

[0018] The present method can also be (4) the method according to the above (2) or (3), wherein the breaking step includes: a liquid breaking step in which the used absorbent article in the collecting bag is broken together with the collecting bag in the inactivated aqueous solution supplied together with the collecting bag; and a drawing step in which the broken product obtained by the liquid breaking step is drawn together with the inactivated aqueous solution from the liquid breaking step.

[0019] In the present method, by actively discharging the mixture of the broken pieces and the inactivated aqueous solution from the liquid breaking process, it is possible to remove (drain) the dirt of the equipment related to the liquid breaking process with the inactivated aqueous solution, along with the movement of the mixture. Thus, it is possible to maintain the sanitary state of the breaking process to be good.

[0020] The present method can also be (5) the method according to any one of the above (2) to (4), wherein the step of perforating the surface of the collection bag that contacts the inactivated aqueous solution in the perforating step is performed using a protrusion that is capable of moving up and down in the solution tank while rotating around a rotation axis.

[0021] In the present method, the collection bag is perforated using a protrusion that moves up and down in the solution tank while rotating around a rotation axis. Therefore, even if the collection bag is not allowed to sink in the inactivated aqueous solution, it is possible to reliably perforate the collection bag, for example, by moving the protrusion to contact the collection bag toward the upper portion of the solution tank. The collection bag is allowed to sink in the inactivated aqueous solution after the perforation, and thus it is possible to reliably sink the collection bag in the acidic solution in a short time, and it is possible to reduce the processing time and improve the processing efficiency.

[0022] The present method can also be (6) the method according to any one of the above (2) to (4), wherein the step of perforating the surface of the collection bag that contacts the inactivated aqueous solution in the perforating step is performed by feeding the collection bag into the inactivated aqueous solution from the upper portion of the solution tank to contact a protrusion disposed at the lower portion of the solution tank and rotating around a rotation axis.

[0023] In the present method, the collection bag is fed into the inactivated aqueous solution, and the collection bag is perforated using a protrusion at the lower portion of the solution tank. The collection bag is perforated after being allowed to sink in the inactivated aqueous solution, and thus it is possible to reliably prevent the spread of dirt and odor from the used absorbent articles inside the collection bag to the outside. Thus, it is possible to hygienically and safely break the used absorbent articles.

[0024] The present method can also be (7) the method according to the above (1), wherein the breaking step includes a step of feeding the collection bag into the inactivated aqueous solution in the breaking device, while breaking the used absorbent articles inside the collection bag together with the collection bag in the inactivated aqueous solution.

[0025] In the present method, the inactivated aqueous solution is stored in advance in the breaking device, and the used absorbent articles inside the collection bag are broken together with the collection bag in the inactivated aqueous solution in the inactivated aqueous solution. Thus, it is possible to reliably break the used absorbent articles inside the collection bag together with the collection bag in the inactivated aqueous solution.

[0026] The present method can also be (8) the method according to any one of (1) or (7) above, wherein the separating step includes a step of directly receiving the crushed material and the inactivated aqueous solution by the separating device disposed directly below the crushing device.

[0027] In the present method, the separating device is disposed directly below the crushing device, so the crushed material and the inactivated aqueous solution crushed by the crushing device can be reliably and promptly transferred to the separating device. Thus, even if dirt, bacteria, or odor is mixed in the inactivated aqueous solution, the effects can be suppressed to be low.

[0028] The present method can also be (9) the method according to any one of (1) to (8) above, wherein the crushing step includes a step of crushing the used absorbent article together with the collection bag so that the average value of the size of the crushed material is 50 mm or more and 100 mm or less.

[0029] In the present method, in the crushing step, the crushing is performed by adjusting the crushing device so that the average value of the size of the crushed material is 50 mm or more and 100 mm or less. Here, the size of the crushed material is set to the length of the long side in the case of a rectangular shape, to the diameter in the case of a circle, and to the length of the side of a square corresponding to the area in the case of an indefinite shape. In this case, a cut can be reliably formed on the back sheet and / or the surface sheet of each used absorbent article, so the pulp fiber can be taken out from the cut substantially without remaining in each used absorbent article. Thus, the recovery rate of the pulp fiber (total amount of regenerated pulp fiber / total amount of pulp fiber of the used absorbent article supplied), the recovery rate of the superabsorbent polymer can be improved. If the average value of the size is less than 50 mm, other materials (examples: film (back sheet or the like), nonwoven fabric (surface sheet or the like), elastomer (rubber for leakage barrier or the like)) other than the pulp fiber and the superabsorbent polymer are excessively cut, and it is difficult to separate the pulp fiber and the superabsorbent polymer. As a result, other materials mixed into the regenerated pulp fiber and the superabsorbent polymer increase, and the recovery rate of the pulp fiber and the superabsorbent polymer decreases. On the other hand, if the average value of the size is more than 100 mm, it is difficult to form a cut on the used absorbent article. As a result, used absorbent articles from which the pulp fiber and the superabsorbent polymer cannot be taken out are generated, and the recovery rate of the pulp fiber and the superabsorbent polymer decreases.

[0030] The present method can also be (10) the method according to any one of (1) to (9) above, wherein the step of crushing the used absorbent article together with the collection bag in the inactivated aqueous solution in the crushing step is performed using a double shaft crusher.

[0031] In the present method, the process of crushing the used absorbent article is performed using a double shaft crusher (examples: double shaft rotary crusher, double shaft differential crusher, double shaft shearing crusher). Therefore, it is possible to make the size of the crushed product coincide with a substantially predetermined range. Thus, it is possible to suppress the crushed product from becoming too small, foreign matter from being mixed in the pulp fiber, or the crushed product from becoming too large, resulting in a used absorbent article from which the pulp fiber cannot be taken out, and thus the recovery rate of the pulp fiber decreases.

[0032] The present method can also be (11) the method according to any one of (1) to (10) above, wherein the inactivation aqueous solution is an acidic aqueous solution.

[0033] In the present method, the inactivation aqueous solution is an acidic aqueous solution, and thus it is possible to reliably dehydrate and inactivate the superabsorbent polymer in the used absorbent article. In particular, if crushing is performed in an acidic aqueous solution, alkaline volatile components derived from excrement such as urine do not volatilize but remain in the acidic aqueous solution, and thus it is possible to suppress the generation of odor caused by alkaline gas such as ammonia. Thus, in the crushing process, the used absorbent article does not greatly expand, and it is possible to easily perform crushing, and it is possible to improve the processing efficiency.

[0034] The present method can also be (12) the method according to (11) above, wherein the acidic aqueous solution contains citric acid.

[0035] In the present method, the acidic aqueous solution contains citric acid (example: concentration 0.5 mass% to 2.0 mass%), and thus it is possible to dehydrate and inactivate the superabsorbent polymer in the used absorbent article, and there is almost no adverse effect of the acid on the workers, and it is also possible to suppress the corrosion of the equipment of each process by the acid.

[0036] A system used for a method of recovering pulp fiber from a used absorbent article containing pulp fiber and a superabsorbent polymer according to the present application is described below. (13) A system used for a method of recovering pulp fiber from a used absorbent article containing pulp fiber and a superabsorbent polymer, wherein the system includes: a container into which a collection bag in which the used absorbent article is enclosed is put; a crushing device that communicates with the container, and crushes the used absorbent article in the collection bag in an inactivation aqueous solution while transferring the collection bag in the container; and a separation device that separates the pulp fiber, the superabsorbent polymer, and the inactivation aqueous solution from the crushed product and the inactivation aqueous solution obtained by the crushing device.

[0037] In the present system, at least after the collection bag is received in the container, the collection bag is transferred to a crushing device that is independently provided with respect to the container, and in the crushing device, the high-absorbency polymer of the used absorbent article in the collection bag is inactivated in the inactivating aqueous solution, and the used absorbent article is crushed together with the collection bag. That is, when the used absorbent article is crushed, the crushing is performed in the inactivating aqueous solution in the crushing device that is independent with respect to the container, and after the crushing, the inactivating aqueous solution and the crushed matter are transferred to the separation device. Therefore, even if the inactivating aqueous solution is mixed with dirt, bacteria, or odor is generated, the inactivating aqueous solution mixed with the dirt, bacteria, or the crushed matter hardly reaches the container. Thus, the crushing can be performed in the container with hardly any dirt, bacteria remaining. Further, the odor can be sealed with the inactivating aqueous solution, and thus the generation of odor can also be suppressed to be low. In particular, if the crushing is performed in the inactivating aqueous solution, the alkaline volatile components originating from the excrement such as urine do not volatilize but remain in the inactivating aqueous solution, and thus the generation of odor caused by alkaline gas such as ammonia can be suppressed. Thus, when the used absorbent article is crushed, the scattering of dirt, bacteria, or the release of odor accompanying the dirt can be suppressed. That is, the used absorbent article can be crushed hygienically and safely, and the cost of hygiene management of the operation and maintenance can be suppressed.

[0038] The present system can also be (14) the system according to the above (13), wherein the system further includes a bag breaking device including: a solution tank as the container for accumulating the inactivating aqueous solution; and a hole portion provided in the solution tank to open a hole in a surface of the collection bag that contacts the inactivating aqueous solution when the collection bag is put into the solution tank, the crushing device transfers the collection bag, which is sunk below the water surface of the inactivating aqueous solution with the hole opened, to the crushing device from the solution tank together with the inactivating aqueous solution, and crushes the used absorbent article in the collection bag together with the collection bag in the inactivating aqueous solution.

[0039] In the present system, at least by opening the hole in the collection bag, the inactivated aqueous solution is introduced from the hole into the collection bag, the inactivated aqueous solution is used to inactivate the superabsorbent polymer contained in the used absorbent article, and the collection bag is substantially sunk below the water surface of the inactivated aqueous solution. Thus, the collection bag sunk below the water surface of the inactivated aqueous solution can be transferred from the solution tank together with the inactivated aqueous solution while the used absorbent article is broken together with the collection bag in the inactivated aqueous solution. Thus, before the breaking is started, there is almost no possibility that dirt, bacteria, or odor is mixed in the inactivated aqueous solution. Also, when the used absorbent article is broken, even if dirt, bacteria, or odor is mixed in the inactivated aqueous solution, since the inactivated aqueous solution mixed with the dirt and the bacteria is sent out from the solution tank together with the broken product at substantially the same time as the breaking, the dirt and the bacteria can be drained away without remaining in the solution tank. Further, the odor can be sealed by the inactivated aqueous solution, and thus the generation of odor can also be suppressed to be low.

[0040] The present system can also be (15) the system according to the above (14), wherein the bag breaking device and the breaking device are different devices.

[0041] In the present system, the bag breaking device that opens the hole in the collection bag and the breaking device that breaks the used absorbent article together with the collection bag are different devices. Thus, the opening of the hole and the breaking of the used absorbent article can be reliably performed at different positions, and thus the inactivated aqueous solution can be introduced from the hole into the collection bag, and the collection bag can be reliably sunk below the water surface of the inactivated aqueous solution, and then the breaking can be performed at different positions. Thus, at the time of breaking, it is possible to prevent a part of the collection bag from being exposed on the water surface of the inactivated aqueous solution, the opening (crack) of the hole from being exposed on the water surface of the inactivated aqueous solution, and thus the dirt and the bacteria of the used diaper from being scattered, or the odor generated along with the dirt from being released.

[0042] The present system can also be (16) the system according to the above (14) or (15), wherein the breaking device includes a breaking section that breaks the used absorbent article in the collection bag together with the collection bag in the inactivated aqueous solution supplied together with the collection bag, and a pump that draws the broken product from the breaking section together with the inactivated aqueous solution.

[0043] In the present system, by actively discharging the mixture of the broken product and the inactivated aqueous solution from the breaking section by the pump, it is possible to remove (drain away) the dirt of the breaking section by the inactivated aqueous solution along with the movement of the mixture. Thus, it is possible to maintain the hygiene state of the breaking device to be good.

[0044] The system can also be (17) the system according to any one of (14) to (16) described above, wherein the opening portion of the bag breaking device includes a protrusion that rotates around a rotation axis and is capable of moving up and down in the solution tank.

[0045] In the system, the protrusion that rotates around a rotation axis and moves up and down in the solution tank is used to open the bag on the collection bag. Therefore, even if the collection bag is not allowed to sink in the inactivated water solution, for example, by moving the protrusion to the upper portion of the volume tank to contact the collection bag, the bag can be reliably opened on the collection bag. After the opening, the collection bag is allowed to sink in the inactivated water solution, so the collection bag can be reliably sunk in the acidic solution in a short time, the processing time can be reduced, and the processing efficiency can be improved.

[0046] The system can also be (18) the system according to any one of (14) to (16) described above, wherein the opening portion of the bag breaking device includes a protrusion that rotates around a rotation axis and is capable of moving up and down in the solution tank.

[0047] In the system, the collection bag is fed into the inactivated water solution, and the protrusion of the lower portion of the solution tank is used to open the bag on the collection bag. After the collection bag is allowed to sink in the inactivated water solution, the spread of dirt and odor from the used absorbent article in the collection bag to the outside can be reliably prevented. Thus, the used absorbent article can be hygienically and safely broken.

[0048] The method can also be (19) the system according to (13) described above, wherein the breaking device feeds the collection bag into the inactivated water solution in the breaking device, and the used absorbent article in the collection bag is broken in the inactivated water solution together with the collection bag.

[0049] In the system, the inactivated water solution is pre-stored in the breaking device, and the used absorbent article in the collection bag is broken in the inactivated water solution together with the collection bag in the inactivated water solution. Therefore, the used absorbent article in the collection bag can be reliably broken in the inactivated water solution together with the collection bag.

[0050] The method can also be (20) the system according to (13) or (19) described above, wherein the separation device is arranged directly below the breaking device, and the broken matter and the inactivated water solution are directly accepted from the breaking device.

[0051] In the present system, the separation device is arranged directly below the crushing device, so that the crushed product and the inactivation aqueous solution crushed by the crushing device can be reliably and quickly transferred to the separation device. Thus, even if dirt, bacteria, or odor is mixed in the inactivation aqueous solution, the effects can be suppressed to a low level.

[0052] The present system can also be (21) the system according to any one of (13) to (20) above, wherein the crushing device crushes the used absorbent article together with the collection bag so that the average value of the size of the crushed product is 50 mm or more and 100 mm or less.

[0053] In the present system, the crushing device is adjusted to crush so that the average value of the size of the crushed product is 50 mm or more and 100 mm or less. Here, the size of the crushed product is set to the length of the long side or the like in the case where the shape is rectangular, as described above. In this case, a cut can be reliably formed on the back sheet and / or the surface sheet of each used absorbent article, so that the pulp fiber can be taken out from the cut substantially without residue in each used absorbent article. Thus, the recovery rate of the pulp fiber and the recovery rate of the superabsorbent polymer can be improved. If the average value of the size is less than 50 mm, other materials than the pulp fiber and the superabsorbent polymer are cut too small, so that it is difficult to separate the pulp fiber and the superabsorbent polymer. As a result, other materials mixed into the regenerated pulp fiber and the superabsorbent polymer increase, and the recovery rate of the pulp fiber and the superabsorbent polymer decreases. On the other hand, if the average value of the size is more than 100 mm, it is difficult to form a cut on the used absorbent article. As a result, a used absorbent article from which the pulp fiber and the superabsorbent polymer cannot be taken out is generated, and the recovery rate of the pulp fiber and the superabsorbent polymer decreases.

[0054] The present system can also be (22) the system according to any one of (13) to (21) above, wherein the crushing device includes a double-shaft crusher.

[0055] In the present system, a double-shaft crusher (examples: double-shaft rotary crusher, double-shaft differential crusher, double-shaft shear crusher) is used as the crushing device for the used absorbent article. Thus, the size of the crushed product can be made to coincide with a substantially predetermined range. Thus, it is possible to suppress the crushed product from becoming too small, foreign matter from being mixed in the pulp fiber, or the crushed product from becoming too large, a used absorbent article from which the pulp fiber cannot be taken out being generated, and thus the recovery rate of the pulp fiber decreasing.

[0056] The present system can also be (23) the system according to any one of (13) to (22) above, wherein the inactivation aqueous solution is an acidic aqueous solution.

[0057] In this system, the inactivation aqueous solution is acidic, thus reliably dehydrating and inactivating the highly absorbent polymers in used absorbent materials. In particular, since the crushing process takes place in an acidic aqueous solution, alkaline volatile components derived from excrement such as urine do not evaporate but remain in the acidic solution, thereby suppressing the generation of odors caused by alkaline gases such as ammonia. Therefore, during the crushing process, the used absorbent materials do not swell significantly, allowing for easy crushing and improving processing efficiency.

[0058] The system may also be, (24) the system described in (23) above, wherein the acidic aqueous solution contains citric acid.

[0059] In this system, the acidic aqueous solution contains citric acid (e.g., concentration 0.5% to 2.0% by mass), which can dehydrate and inactivate the superabsorbent polymers in used absorbent materials. Furthermore, there is almost no adverse effect of acid on workers, and it can also inhibit acid corrosion of equipment in each process.

[0060] Effects of the Invention

[0061] According to the method and system of the present invention, costs can be controlled when recovering pulp fibers from used absorbent articles placed into collection bags, and the used absorbent articles can be hygienically and safely crushed. Attached Figure Description

[0062] FIG. 1 This is a block diagram illustrating an example of a system implementation.

[0063] FIG. 2 It means FIG. 1 A schematic diagram of the structure of the bag breaking device and the crushing device.

[0064] FIG. 3 It means FIG. 1 A schematic diagram of another structural example of a bag-breaking device and a crushing device.

[0065] FIG. 4 It means FIG. 1 A partially enlarged view of the structure of a crushing device.

[0066] FIG. 5 This is a flowchart illustrating an example of a method for implementing the method.

[0067] FIG. 6 This is a block diagram illustrating another example of a system implementation.

[0068] FIG. 7 It means FIG. 6 A schematic diagram of the structure of a crushing and separating device.

[0069] FIG. 8 is a flowchart showing another example of the method of the embodiment.

[0070] FIG. 9 is a graph showing the relationship between the size of the crushed product and the processing amount and the foreign matter amount in the crushing step. DETAILED DESCRIPTION

[0071] Hereinafter, a method of recycling pulp fibers from used absorbent articles containing pulp fibers and superabsorbent polymers of the embodiment will be described. The used absorbent articles herein include absorbent articles used by a user, and include absorbent articles in which excretions of the user have been absorbed / retained, and absorbent articles used but not having absorbed / retained excretions, and absorbent articles not used but discarded. As the absorbent articles, for example, paper diapers, urine-absorbing pads, sanitary napkins, bed sheets, and pet sheets can be given. Note that the method of recycling pulp fibers from used absorbent articles of the embodiment can also be said to be a method of producing recycled pulp fibers from used absorbent articles, since recycled pulp fibers are produced. Further, the method of recycling pulp fibers from used absorbent articles of the embodiment can also be said to be a method of recycling superabsorbent polymers from used absorbent articles, or a method of producing recycled superabsorbent polymers, since recycled superabsorbent polymers are produced by separating the superabsorbent polymers together with the pulp fibers in the middle of the process. Here, the method of recycling pulp fibers from used absorbent articles will be described.

[0072] (First Embodiment)

[0073] The first embodiment will be described.

[0074] First, an example of the structure of the absorbent article will be described. The absorbent article includes a surface sheet, a back sheet, and an absorbent body disposed between the surface sheet and the back sheet. As an example of the size of the absorbent article, a length of about 15 cm to 100 cm and a width of 5 cm to 100 cm can be given. Note that the absorbent article can include further other members such as a diffusion sheet, a leakage-preventing wall, and the like, which are generally provided in absorbent articles.

[0075] As the structural member of the surface sheet, for example, a liquid-permeable nonwoven fabric, a synthetic resin film having liquid-permeable holes, a composite sheet thereof, and the like can be exemplified. As the structural member of the back sheet, for example, a liquid-impermeable nonwoven fabric, a liquid-impermeable synthetic resin film, a composite sheet thereof can be exemplified. As the structural member of the diffusion sheet, for example, a liquid-permeable nonwoven fabric can be exemplified. As the structural member of the leakage-preventing wall, for example, a liquid-impermeable nonwoven fabric can be exemplified, and an elastic member such as rubber can also be included. Here, as the material of the nonwoven fabric and the synthetic resin film, there is no particular limitation as long as it can be used as an absorbent article, but for example, an olefin-based resin such as polyethylene and polypropylene, a polyamide-based resin such as 6-nylon and 6,6-nylon, a polyester-based resin such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), and the like can be exemplified. In the present embodiment, an absorbent article in which the structural member of the back sheet is a film and the structural member of the surface sheet is a nonwoven fabric is exemplified.

[0076] As the structural member of the absorbent body, an absorbent body material, that is, pulp fibers and a superabsorbent polymer can be exemplified. As the pulp fibers, there is no particular limitation as long as it can be used as an absorbent article, but for example, a cellulose-based fiber can be exemplified. As the cellulose-based fiber, for example, wood pulp, crosslinked pulp, non-wood pulp, regenerated cellulose, semi-synthetic cellulose, and the like can be exemplified. As the size of the pulp fibers, for example, the average value of the length-diameter of the fibers can be exemplified as several tens of μm, and preferably 20 μm to 40 μm, and the average value of the fiber length can be exemplified as several mm, and preferably 2 mm to 5 mm. As the superabsorbent polymer (SAP), there is no particular limitation as long as it can be used as an absorbent article, but for example, a water-absorbent polymer of a polyacrylate-based, a polysulfonate-based, a maleate-based can be exemplified. As the size of the superabsorbent polymer (at the time of drying), for example, the average value of the particle diameter can be exemplified as several hundreds of μm, and preferably 200 μm to 500 μm.

[0077] One face and the other face of the absorbent body are joined to the surface sheet and the back sheet, respectively, by means of an adhesive. In plan view, the portion (peripheral edge portion) of the surface sheet, which extends to the outside of the absorbent body in a manner of surrounding the absorbent body, is joined to the portion (peripheral edge portion) of the back sheet, which extends to the outside of the absorbent body in a manner of surrounding the absorbent body, by means of an adhesive. Thus, the absorbent body is enclosed inside the joined body of the surface sheet and the back sheet. As the adhesive, there is no particular limitation as long as it can be used as an absorbent article, and the joining force is reduced by softening or the like with warm water as described later, but for example, a hot-melt type adhesive can be exemplified. As the hot-melt type adhesive, for example, a pressure-sensitive or heat-sensitive adhesive of a rubber-based main body such as styrene-ethylene-butadiene-styrene, styrene-butadiene-styrene, styrene-isoprene-styrene, or an olefin-based main body such as polyethylene can be exemplified.

[0078] Next, a method of recycling pulp fibers from used absorbent articles in the embodiment using pulp fibers and superabsorbent polymers will be described. In the present embodiment, used absorbent articles are collected / acquired from the outside for reuse (recycling) and used. At this time, a plurality of used absorbent articles are enclosed in a bag for collection (hereinafter, also referred to as "collection bag") so that dirt (excrement and the like), bacteria, and odor do not leak to the outside. In order to prevent excrement from being exposed to the surface side and odor from spreading around, each of the used absorbent articles in the collection bag is collected and the like mainly in a state of being bunched up, a state of being folded, and the like in such a manner that the surface sheet on which excrement is discharged is on the inner side.

[0079] First, a system 1 used in the method of recycling pulp fibers from used absorbent articles will be described. The system 1 is a system that recycles pulp fibers (and preferably superabsorbent polymers) from used absorbent articles to produce recycled pulp fibers (and preferably recycled superabsorbent polymers). FIG. 1 is a block diagram showing an example of the system 1 of the present embodiment. The system 1 includes a bag breaking device 11 and a crushing device 12, and preferably includes a first separation device 13, a first dust removal device 14, a second dust removal device 15, a third dust removal device 16, a second separation device 17, a third separation device 18, an oxidizing agent treatment device 19, and a fourth separation device 20. Hereinafter, a detailed description will be given.

[0080] First, the bag breaking device 11 and the crushing device 12 will be described. The bag breaking device 11 perforates a collection bag containing used absorbent articles in a deactivation aqueous solution. The crushing device 12 crushes the used absorbent articles in the deactivation aqueous solution together with the collection bag, which sinks to the water surface of the deactivation aqueous solution. Here, the deactivation aqueous solution refers to an aqueous solution that deactivates superabsorbent polymers, and by deactivation, the water absorption performance of the superabsorbent polymers is reduced. As a result, the superabsorbent polymers release water to an amount that the water absorption performance can tolerate, i.e., dehydration, in a case where the superabsorbent polymers absorb more water than the reduced water absorption performance. Hereinafter, a case where an acidic aqueous solution is used as the deactivation aqueous solution will be described as an example.

[0081] FIG. 2 is a schematic view showing a structure example of the bag breaking device 11 and the crushing device 12 of FIG. 1

[0082] ​The bag breaking device 11 accumulates the acidic aqueous solution B supplied via a pipe provided with a valve, for example, and perforates the collection bag A placed in the acidic aqueous solution B. The bag breaking device 11 includes a solution tank (container) V and a perforating section 50. The solution tank V is used to accumulate the acidic aqueous solution B. The perforating section 50 is provided in the solution tank V and perforates the collection bag A on a surface thereof in contact with the acidic aqueous solution B when the collection bag A is placed in the solution tank V.

[0083] The perforating section 50 includes a feeding section 30 and a bag breaking section 40. The feeding section 30 feeds (introduces) the collection bag A (physically and forcibly) into the acidic aqueous solution B in the solution tank V. The feeding section 30 can be exemplified by a blender, for example, and includes a stirring blade 33, a support shaft (rotary shaft) 32 for supporting the stirring blade 33, and a driving device 31 for rotating the support shaft 32 along an axis. The stirring blade 33 is rotated around the rotary shaft (support shaft 32) by the driving device 31, thereby generating a vortex in the acidic aqueous solution B. The feeding section 30 draws the collection bag A toward the bottom of the acidic aqueous solution B (solution tank V) by the vortex.

[0084] The bag breaking section 40 is disposed in the lower portion (preferably, the bottom) of the solution tank V and includes a bag breaking knife 41, a support shaft (rotary shaft) 42 for supporting the bag breaking knife 41, and a driving device 43 for rotating the support shaft 42 along an axis. The bag breaking knife 41 is rotated around the rotary shaft (support shaft 42) by the driving device 43, thereby perforating the collection bag A moved to the lower portion of the acidic aqueous solution B (solution tank V). Here, the lower portion of the solution tank V indicates a portion on the lower side than a position at half the height of the solution tank V.

[0085] Note that the bag breaking knife 41 of the perforating section 50 of the bag breaking device 11 can be configured to move in the vertical direction in the solution tank V while being rotated around the rotary shaft (support shaft 42). In this case, the bag breaking knife 41 is moved upward, thereby being able to perforate the collection bag A even if the collection bag A is not moved to the lower portion of the acidic aqueous solution B (solution tank V).

[0086] The breaking device 12 breaks the used absorbent article in the collection bag A sunk to the surface of the acidic aqueous solution B together with the collection bag A. The breaking device 12 includes a breaking section 60 and a pump 63. The breaking section 60 is connected with the solution tank V by a pipe 61, and by opening a valve (not shown) of the pipe 61, the used absorbent article in the collection bag A (mixed liquid 91) mainly sent out from the solution tank V together with the acidic aqueous solution B is broken in the acidic aqueous solution B together with the collection bag A. As the breaking section 60, a double shaft breaker (for example, a double shaft rotary breaker, a double shaft differential breaker, a double shaft shear breaker), for example, SUMI CUTTER (manufactured by Sumitomo Heavy Industries, Environment Co., Ltd.) can be cited. The pump 63 is connected with the breaking section 60 by a pipe 62, and the broken matter obtained by the breaking section 60 is drawn out from the breaking section 60 together with the acidic aqueous solution B (mixed liquid 92), and sent to the next step. The broken matter includes pulp fibers and super absorbent polymers, other materials (raw materials of the collection bag A, films, nonwoven fabrics, elastomers, etc.). The breaking bag device 11 and the breaking device 12 are preferably different devices from each other.

[0087] FIG. 3 is a schematic view of another configuration example of the breaking bag device 11 and the breaking device 12 of FIG. 1 In the example of FIG. 3 The configuration of the breaking bag device 11 is different from that of the example of FIG. 2 The breaking bag device 11 includes a solution tank Va and an opening section 50a. The opening section 50a includes a feeding section 30a and a breaking bag section 40a. The feeding section 30a feeds (presses) the collection bag A into (into) the acidic aqueous solution B in the solution tank Va (physically and forcibly). The feeding section 30a is directly linked to the upper portion of the solution tank Va, includes a cylindrical member 38, a shaft member 36 disposed in the cylindrical member 38 in a manner that the axis thereof overlaps with the axis of the cylinder, and a plate-shaped member 37 that traces a spiral around the shaft member 36 in the axial direction. By sequentially pressing the collection bag A along the spiral of the plate-shaped member 37 from above the feeding section 30a, the collection bag A is fed into the solution tank Va filled with the acidic aqueous solution B from below the feeding section 35.

[0088] The bag breaking portion 40a is configured so as to extend from the bottom of the solution tank Va toward the inside, and includes a rotating rotor 41a, a support shaft (rotary shaft) 42 for supporting the rotating rotor 41a, and a driving device 43 for rotating the support shaft 42 along the axis. The rotating rotor 41a has a conical main body portion 45 and a plurality of protrusion portions 44 arranged on the side surface of the main body portion 45. The rotating rotor 41a is rotated around the rotary shaft (support shaft 42) in the acidic aqueous solution B (solution tank Va), and thereby perforates the collection bag A moving into the acidic aqueous solution B (solution tank Va) with the plurality of protrusion portions 44. As a member obtained by integrating the bag breaking portion 40a and the solution tank Va, for example, a mixed pulper (manufactured by Aikawa Tekko Co., Ltd.) can be cited.

[0089] FIG. 4 is a partial enlarged view of a structure example of a crushing portion 60 of a crushing device 12. FIG. 1 is a partial enlarged view of a structure example of a crushing portion 60 of a crushing device 12. The double shaft crusher of the crushing portion 60 has both end portions rotatably supported to a housing 75, and has a pair of rotary shafts 72, 72 arranged in parallel with each other. Each rotary shaft 72 is rotated toward the inside of the housing 75 by a driving device 71 not shown. A rotary cutter head 74 and a liner 73 are alternately attached to each rotary shaft 72 in the axial direction. The size, arrangement, and distance between the pair of rotary shafts 72, 72 of the rotary cutter head 74 and the liner 73 of each rotary shaft 72 are set so that the rotary cutter head 74 and the liner 73 attached to the pair of rotary shafts 72 are opposed to and engaged with each other. At this time, the size of the crushed product can be mainly adjusted according to the difference a between the radius of the rotary cutter head 74 and the liner 73 and the thickness b of the rotary cutter head 74 in the axial direction. For example, in a case where the average value of the size (plan view) of the crushed product is about 60 mm square, the size can be realized by adjusting a ≈ b ≈ 60 mm. Here, the size of the crushed product is set to the length of the long side in a case where the shape of the crushed product in plan view is substantially rectangular, to the length of one side of a square approximated when the area of the crushed product is the same as the square in a case where the shape is indefinite, and to the diameter in a case where the shape is circular. The average value of the size of the crushed product is arbitrarily selected from ten crushed products (examples: surface sheet or back sheet, etc.) immediately after crushing, and is calculated from the average value. The crushed product has an area larger than a x b before crushing.

[0090] Referring to FIG. 1 , the first separation device 13 stirs the mixed liquid 92 containing the crushed product obtained by the crushing device 12 and the acidic aqueous solution, performs cleaning for removing dirt (excrement, etc.) from the crushed product, and simultaneously separates the pulp fiber, the superabsorbent polymer, and the acidic aqueous solution (mixed liquid 93) from the mixed liquid 92, and sends them to the first dust removing device 14.

[0091] As the first separation device 13, for example, a washing machine provided with a washing tub and a water tub surrounding the same can be cited. Among them, the washing tub (rotary drum) functions as a washing tub and a screening tub (separation tub). The size of the plurality of through holes provided to the circumferential surface of the washing tub is set to a size through which pulp fibers and superabsorbent polymers in the crushed material easily pass and through which other materials hardly pass. As the washing machine, for example, a horizontal washing machine ECO-22B (manufactured by Kabushiki Kaisha Inabata Seizo) can be cited.

[0092] Note that, between the bag breaking device 11 and the first separation device 13, in the case where an acidic aqueous solution is not used as the inactivation aqueous solution, the acidic aqueous solution can be added from the first dust removing device 14 so that the inactivation aqueous solution containing pulp fibers and superabsorbent polymers supplied to the first dust removing device 14 becomes substantially an acidic aqueous solution. In this case, the specific gravity and size of the superabsorbent polymers can be easily adjusted with the pH value.

[0093] The first dust removing device 14 separates the acidic aqueous solution (mixed liquid 93) containing pulp fibers and superabsorbent polymers sent out from the first separation device 13 into pulp fibers and superabsorbent polymers (mixed liquid 94) in the acidic aqueous solution and other materials (foreign matter) using a screen having a plurality of openings while maintaining the pH value within a predetermined range. In order to maintain the pH value within the predetermined range, for example, a liquid (example: water) that changes the pH value is not added halfway, or in the case where a liquid is added, a liquid (example: an acidic aqueous solution) having substantially the same pH value is set. The predetermined range is set to a range in which the change in the pH value is within ±1.0.

[0094] The first dust removing device 14, for example, can cite a screen separator (coarse screen separator). Among them, the opening of the screen (screen) is not particularly limited, and for example, a slit, a round hole, a square hole, a mesh, and the like can be cited, and a round hole is used here. The size of the opening, that is, the size (diameter) of the round hole is set to a size through which pulp fibers and superabsorbent polymers can pass and a size through which other materials (foreign matter) that cannot be removed by the first separation device 13 hardly pass, and is a size larger than the size of the opening of the screen of the second dust removing device 15. The size of the round hole is, for example, 2 mm to 5 mm φ in diameter, and thereby other materials (foreign matter) of 10 mm square or more can be removed at least. In the case of a slit, the size (width) of the slit is, for example, 2 mm to 5 mm.

[0095] Note that, from the viewpoint of improving the efficiency of removal of foreign matter, the mixed liquid 93 sent out from the first separation device 13 can be pressurized at the same time (example: 0.5 kgf / cm 2 ~ 1 kgf / cm 2), and supplies it to the first dust removing device 14. The first dust removing device 14 can be exemplified by a packing pulper (manufactured by SATOMI CO., LTD.).

[0096] The second dust removing device 15 separates the acidic aqueous solution (mixed liquid 94) containing the pulp fiber and the super absorbent polymer, which is sent from the first dust removing device 14, into the pulp fiber and the super absorbent polymer in the acidic aqueous solution (mixed liquid 95) and other materials (foreign matter) using a screen having a plurality of openings while maintaining the pH value within a predetermined range.

[0097] The second dust removing device 15 can be exemplified by a screen separator. The opening of the screen is not particularly limited, and can be exemplified by a slit, a circular hole, a square hole, a mesh, and a slit is used herein. The size (width) of the slit is set to a size through which the pulp fiber and the super absorbent polymer can pass, and a size through which the other materials (foreign matter) that cannot be removed by the first dust removing device 14 are difficult to pass. The size of the slit is, for example, 0.2 mm to 0.5 mm in width, and thus the other materials (foreign matter) of 3 mm square or more can be removed at least. In the case of the circular hole, the size (diameter) of the circular hole is, for example, 0.2 mm to 0.5 mm φ in diameter.

[0098] Note that, from the viewpoint of improving the efficiency of removal of foreign matter, the mixed liquid 94 sent from the first dust removing device 14 can be supplied to the second dust removing device 15 while being pressurized (exemplified: 0.5 kgf / cm 2 ~ 2 kgf / cm 2 ). The pressure is preferably higher than that of the first dust removing device 14 from the viewpoint of removing relatively small foreign matter. As the second dust removing device 15, a Lamo screen (manufactured by AICHI SEKI CO., LTD.) can be exemplified.

[0099] The third dust removing device 16 centrifugally separates the acidic aqueous solution (mixed liquid 95) containing the pulp fiber and the super absorbent polymer, which is sent from the second dust removing device 15, while maintaining the pH value within a predetermined range, and separates the pulp fiber and the super absorbent polymer in the acidic aqueous solution (mixed liquid 96) and other materials (heavy foreign matter).

[0100] The third dust removing device 16 can be exemplified by a cyclone separator. The acidic aqueous solution (mixed liquid 95) containing the pulp fiber and the super absorbent polymer is supplied into an inverted conical housing (not shown) of the third dust removing device 16 at a predetermined flow rate, so that the pulp fiber and the super absorbent polymer in the acidic aqueous solution, which have a relatively light specific gravity, rise, and the foreign matter (metal or the like), which has a specific gravity heavier than that of the pulp fiber and the super absorbent polymer, falls. As the third dust removing device 16, an ACT low concentration cleaner (manufactured by AICHI SEKI CO., LTD.) is exemplified.

[0101] The second separation device 17 separates the acidic aqueous solution (mixture 96) containing pulp fibers and superabsorbent polymers, which is sent from the third dust removal device 16, into pulp fibers in an acidic aqueous solution (mixture 97) and superabsorbent polymers in an acidic aqueous solution using a screen having a plurality of openings. Thus, it can also be considered that the second separation device 17 is a dewatering machine that removes the acidic aqueous solution together with the superabsorbent polymers from the mixture 96.

[0102] The second separation device 17 can be exemplified by a drum screen separator, for example. The openings of the drum screen are not particularly limited and can be exemplified by a slit, a round hole, a square, a mesh, but a slit is used herein. The size (width) of the slit is set to a size through which the superabsorbent polymers can pass and is a size through which the pulp fibers are difficult to pass. In the case of a slit, the size of the slit is, for example, 0.2 mm to 0.8 mm in width, whereby at least many superabsorbent polymers can be removed. In the case of a round hole, the size of the round hole is, for example, 0.2 mm to 0.8 mm in diameter φ. As the second separation device 17, a drum screen dewaterer (manufactured by Toyo Screen Co., Ltd.) can be exemplified.

[0103] The third separation device 18 separates the pulp fibers, the superabsorbent polymers that remain without being separated, and the acidic aqueous solution (mixture 97), which are sent from the second separation device 17, into a solid (mixture 98) containing the pulp fibers and the superabsorbent polymers and a liquid containing the superabsorbent polymers and the acidic aqueous solution using a screen having a plurality of openings, and applies pressure to the solid to crush the superabsorbent polymers in the solid. Thus, the third separation device 18 can also be considered to be a dewatering machine of a pressurized dewatering method that removes the acidic aqueous solution together with the superabsorbent polymers from the mixture 97. The solid (mixture 98) contains some acidic aqueous solution.

[0104] The third separation device 18 is, for example, a screw press dehydrator. It includes a cylindrical screen, a screw shaft extending along the axis of the cylinder of the screen, and a screw blade provided on the outer side of the screw shaft and rotating along the inner circumferential surface of the screen. The openings of the screen are not particularly limited and can be, for example, slits, round holes, squares, meshes, but slits are used here. The size (width) of the slits is set to a size through which the superabsorbent polymer can pass and a size through which the pulp fibers hardly pass. In the case of slits, the size of the slits is, for example, 0.1 mm to 0.5 mm in width, and at least the remaining superabsorbent polymer can be removed. The third separation device 18 discharges the liquid containing the superabsorbent polymer and the acidic aqueous solution from the slits on the side of the screen, and discharges the solid containing the pulp fibers and the superabsorbent polymer from the gap between the adjusted lid at the top end of the screen while crushing the superabsorbent polymer. The pressure applied to the pressing of the lid is, for example, 0.01 MPa or more and 1 MPa or less. As the third separation device 18, a screw press dehydrator (manufactured by Kawaguchi Seimitsu Co., Ltd.) can be used.

[0105] The oxidizing agent treatment device 19 treats the pulp fibers (mixture 98) containing the crushed superabsorbent polymer in the solid discharged from the third separation device 18 using an aqueous solution containing an oxidizing agent (treatment liquid). Thereby, the superabsorbent polymer is oxidatively decomposed and removed from the pulp fibers, and the pulp fibers not containing the superabsorbent polymer are discharged together with the treatment liquid (mixture 99).

[0106] The oxidizing agent treatment device includes, for example, a treatment tank and an ozone supply device in the case of using ozone as the oxidizing agent. The treatment tank stores an acidic aqueous solution as the treatment liquid. The ozone supply device supplies ozone-containing gas as a gaseous substance to the treatment tank. As the ozone supply device, an ozone generator, such as an ozone water exposure tester ED-OWX-2 manufactured by Eco Design Co., Ltd. or an ozone generator OS-25V manufactured by Mitsubishi Electric Corporation, can be used. The nozzle of the ozone supply device is disposed at the lower portion of the treatment tank and has, for example, a tubular or flat plate shape. The nozzle supplies the ozone-containing gas Z as a plurality of fine bubbles to the treatment liquid. As the treatment liquid, an acidic aqueous solution is preferable from the viewpoint of suppressing the inactivation of ozone and inactivating the superabsorbent polymer, and an organic acid is preferable from the viewpoint of reducing the influence of the acid on the workers and the device, and citric acid is preferable from the viewpoint of removing metals.

[0107] Note that, although ozone gas is used as the oxidizing agent, the present embodiment is not limited to this example, and other oxidizing agents can be used, and even if the oxidizing agent is not gaseous, a liquid oxidizing agent or a solid oxidizing agent can be melted into a liquid. As the oxidizing agent, for example, chlorine dioxide, peracetic acid, sodium hypochlorite, and hydrogen peroxide can be used.

[0108] The fourth separation device 20 separates the pulp fiber from the treatment liquid (mixed liquid 99) containing the pulp fiber treated by the oxidizing agent treatment device 19 using a screen having a plurality of openings, thereby recovering the pulp fiber, and generates recycled pulp fiber.

[0109] As the fourth separation device 20, for example, a screen separator can be cited. The opening of the screen is not particularly limited, and for example, a slit, a round hole, a square hole, a mesh can be cited, but a slit is used here. The size (width) of the slit is a size at which the pulp fiber hardly passes through. The size of the slit is, for example, 0.2 mm to 0.8 mm in width. In the case of a round hole, the size of the round hole is, for example, 0.2 mm to 0.8 mm φ in diameter.

[0110] Note that the system 1 preferably includes an ozone treatment device 22, a pH adjusting device 23, and a water storage tank 24. These devices are devices for regenerating and reusing the acidic aqueous solution used in the system 1. By reusing the acidic aqueous solution, it is possible to reduce the cost of the acidic aqueous solution. The ozone treatment device 22 performs sterilization treatment on the acidic aqueous solution 101 after the superabsorbent polymer is further separated from the acidic aqueous solution in which the superabsorbent polymer is separated from the used absorbent article by the second separation device 17, using an ozone-containing aqueous solution. The pH adjusting device 23 adjusts the pH of the acidic aqueous solution 102 on which sterilization treatment is performed using the ozone-containing aqueous solution, and generates a regenerated acidic aqueous solution 103. The water storage tank 24 is used to store the remaining portion of the regenerated acidic aqueous solution 103.

[0111] Next, a method of recovering pulp fiber from a used absorbent article will be described. This method is a method of recovering pulp fiber (and preferably superabsorbent polymer) from a used absorbent article, thereby generating recycled pulp fiber (and preferably recycled superabsorbent polymer). FIG. 6 is a flowchart showing an example of the method of the present embodiment. The method includes the opening process S11 and the crushing process S12, and preferably includes the first separation process S13, the first dust removal process S14, the second dust removal process S15, the third dust removal process S16, the second separation process S17, the third separation process S18, the oxidizing agent treatment process S19, and the fourth separation process S20. Hereinafter, a detailed description will be given.

[0112] The opening process S11 is performed using the bag breaking device 11. The collection bag A in which the used absorbent article is enclosed is put into the solution tank V in which the acidic aqueous solution B is accumulated, and the surface of the collection bag A which contacts the acidic aqueous solution B is opened. The acidic aqueous solution B surrounds and seals the periphery of the collection bag A so that the dirt, bacteria, odor of the used absorbent article in the collection bag A is not released to the outside when the collection bag A is opened. If the acidic aqueous solution enters into the collection bag A from the hole, the gas in the collection bag A is discharged to the outside of the collection bag A, the specific gravity of the collection bag A is heavier than that of the acidic aqueous solution B, and the collection bag A sinks in the acidic 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.

[0113] By inactivating the superabsorbent polymer in the used absorbent article, the water absorption capacity of the superabsorbent polymer is reduced, and the superabsorbent polymer is dehydrated and the particle size is reduced, so that the subsequent processes are facilitated and the efficiency of the processes is improved. The use of an acidic aqueous solution, i.e. an aqueous solution of an inorganic acid and an organic acid, as the inactivating aqueous solution is because, compared to an aqueous solution of lime, calcium chloride, etc., ash does not remain on the pulp fibers, and because the degree of inactivation (particle size, specific gravity) can be easily adjusted by the pH value. The pH value of the acidic aqueous solution 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 value is too high, the water absorption capacity of the superabsorbent polymer cannot be sufficiently reduced. In addition, it can also reduce the sterilization ability. If the pH value is too low, it can corrode the equipment, and a large amount of alkaline chemical agent is required for neutralization treatment during wastewater treatment. In particular, in order to separate the pulp fibers and the superabsorbent polymer from other materials, it is preferable that the size and specific gravity of the pulp fibers are close to those of the superabsorbent polymer. Therefore, by setting the pH value of the acidic aqueous solution to 1.0 or more and 4.0 or less, the superabsorbent polymer can be made smaller by inactivation, and thus the size and specific gravity of the pulp fibers can be made close to those of the superabsorbent polymer. As the organic acid, for example, citric acid, tartaric acid, glycolic acid, malic acid, succinic acid, acetic acid, ascorbic acid, etc. can be listed, but hydroxycarbonic acid ester-based organic acids such as citric acid, tartaric acid, gluconic acid, etc. are particularly preferable. By the chelating effect of citric acid, metal ions, etc. in the excreta can be captured and removed, and by the cleaning effect of citric acid, a high dirt component removal effect can be expected. On the other hand, as the inorganic acid, for example, sulfuric acid, hydrochloric acid, nitric acid can be listed, but from the viewpoint of not containing chlorine, cost, etc., sulfuric acid is preferable. The pH value varies depending on the water temperature, so the pH value of the present application refers to the pH value measured at a water solution temperature of 20°C. The organic acid concentration of the organic acid aqueous solution is not particularly limited, but in the case where the organic acid is citric acid, it is preferably 0.5 mass% or more and 4 mass% or less. The inorganic acid concentration of the inorganic acid aqueous solution is not particularly limited, but in the case where the inorganic acid is sulfuric acid, it is preferably 0.1 mass% or more and 0.5 mass% or less.

[0114] For example, in FIG. 2In the bag breaking device 11, first, by rotation of the stirring blade 33 around the rotation shaft (support shaft 32), a vortex is generated in the acidic aqueous solution B, and the collection bag A is physically and forcibly pulled toward the bottom of the acidic aqueous solution B (solution tank V). Then, by rotation of the bag breaking blade 41 around the rotation shaft (support shaft 42), the collection bag A moved to the bottom is perforated by the bag breaking blade 41. Note that in the case where the bag breaking blade 41 is movable up and down in the solution tank V, even if the collection bag A is not pulled toward the bottom of the acidic aqueous solution B (solution tank V) by the vortex, the bag breaking blade 41 can be moved upward to perforate the collection bag A.

[0115] In addition, for example, in the case where the bag breaking device 11 is used in a state where the collection bag A is not perforated, the bag breaking device 11 is configured to be able to perforate the collection bag A by the bag breaking blade 41. FIG. 3 In the bag breaking device 11, first, the collection bag A is sequentially pressed from above the feeding portion 30a along the spiral of the plate-shaped member 37, and is moved on the plate-shaped member 37 along the spiral, and is physically and forcibly fed from below the feeding portion 30a into the solution tank Va filled with the acidic aqueous solution B. Then, the collection bag A moved to the solution tank Va is perforated by the protruding portion 44 by rotation of the rotating rotor 41a around the rotation shaft (support shaft 42).

[0116] The breaking process S12 is performed using the breaking device 12. The acidic aqueous solution B containing the collection bag A perforated and sunk to the bottom of the acidic aqueous solution B, that is, the mixed liquid 91 is discharged from the solution tank V, and the used absorbent article in the collection bag A is broken together with the collection bag A in the acidic aqueous solution B.

[0117] For example, in the case where the breaking device 12 is used in a state where the collection bag A is not perforated, the breaking device 12 is configured to be able to perforate the collection bag A by the bag breaking blade 41. FIG. 2 In the breaking device 12, first, by opening the valve (not shown) of the pipe 61 using the breaking portion 60, the used absorbent article in the collection bag A fed together with the acidic aqueous solution B from the solution tank V by gravity is broken together with the collection bag A in the acidic aqueous solution B (liquid breaking process). At this time, in the breaking portion 60, FIG. 4 In the breaking portion 60, the mixed liquid 91 is supplied between the rotating blade 74 and the liner 73 rotating around one rotation shaft 72 toward the inside of the breaking portion 60 and the rotating blade 74 and the liner 73 rotating around the other rotation shaft 72 toward the inside of the breaking portion 60, and the collection bag A is broken together with the bag. Then, in the breaking portion 60, FIG. 2 In the breaking device 12, the acidic aqueous solution B containing the broken matter (mixed liquid 92) obtained by the breaking portion 60 (liquid breaking process) is drawn from the breaking portion 60 using the pump 63 (drawing process), and is fed to the next process.

[0118] Here, in the crushing process S12, as described later, it is preferable to have a process of crushing the used absorbent articles together with the collection bag A so that the average value of the size of the crushed matter is 50 mm or more and 100 mm or less. In other words, the double shaft crusher of the crushing section 60 is preferably adjusted mainly in accordance with the difference a between the radius of the rotary cutter head 74 and the liner 73 and the thickness b in the axial direction of the rotary cutter head 74 so that the average value of the size of the crushed matter is 50 mm or more and 100 mm or less.

[0119] As the absorbent article, it is assumed to have a length of about 150 mm to 1000 mm and a width of 100 mm to 1000 mm. By crushing in such a manner that the average value of the size of the crushed matter is 50 mm or more and 100 mm or less, it is possible to reliably form a slit on the back sheet and / or the surface sheet of each of the used absorbent articles. Thereby, in each of the used absorbent articles, it is possible to take out the pulp fibers substantially without leaving from the slit, and thus it is possible to improve the recovery rate of the pulp fibers (total amount of the regenerated pulp fibers / total amount of the pulp fibers of the used absorbent articles supplied). If the average value of the size is less than 50 mm, other materials (examples: film (raw material of the collection bag A, back sheet, etc.), nonwoven fabric (surface sheet, etc.), elastomer (rubber for leakage prevention wall, etc.)) other than the pulp fibers are excessively cut, and in the subsequent process, it is difficult to separate these materials from the pulp fibers. As a result, the foreign matter (other materials) mixed into the regenerated pulp fibers increases, and the recovery rate of the pulp fibers decreases. On the other hand, if the average value of the size is greater than 100 mm, it is difficult to form a slit in the used absorbent article. As a result, the size of the crushed matter is large, becomes fluffy, the amount (processing amount) of the crushed matter (disposable diaper) that can be processed in the first separation device 13 of the first separation process S13 decreases, and the efficiency of the processing decreases. Also, there occurs a used absorbent article from which the pulp fibers cannot be taken out, and the recovery rate of the pulp fibers decreases. As to specific examples, this will be described later.

[0120] The first separation process S13 is performed using the first separation device 13. The mixed liquid 92 containing the crushed matter and the acidic aqueous solution obtained by the crushing device 12 is stirred, and washing to remove dirt from the crushed matter is performed, while the mixed liquid 92 is separated into the pulp fibers, the superabsorbent polymer, and the acidic aqueous solution and other materials. At this time, in order to improve the washing effect and / or in order to adjust the pH, an acidic aqueous solution can also be added separately. As a result, the pulp fibers, the superabsorbent polymer, and the acidic aqueous solution (part of which includes other materials and the like) in the mixed liquid 92 are separated by the through holes and are sent out from the first separation device 13 (mixed liquid 93). On the other hand, the other materials in the mixed liquid 92 other than the pulp fibers, the superabsorbent polymer, and the acidic aqueous solution cannot pass through the through holes and remain in the first separation device 13 or are sent out through other paths. Among them, part of the other materials cannot be completely separated and are sent out together with the mixed liquid 93. Here, in the case where a washing machine is used as the first separation device 13, the size of the through holes of the washing tub that functions as a sieve can be cited as 5 mm to 20 mm φ in the case of a round hole, and as a size of substantially the same area as the round hole in the case of a hole of another shape.

[0121] The present method (system) includes at least the hole opening process S11 and the crushing process S12 in the crushing process (the hole opening process S11, the crushing process S12, the first separation process S13) of crushing the used absorbent article as described above.

[0122] Note that, in the hole opening process S11 to the first separation process S13, in the case where an acidic aqueous solution is not used as the inactivation aqueous solution, it is preferable that the acidic aqueous solution be added from the first dust removal process S14 so that the inactivation aqueous solution containing the pulp fibers and the superabsorbent polymer supplied to the first dust removal process S14 becomes substantially an acidic aqueous solution. In this case, the specific gravity and the size of the superabsorbent polymer can be easily adjusted with the pH.

[0123] The first dust removal process S14 is performed using the first dust removal device 14. The acidic aqueous solution containing the pulp fibers and the superabsorbent polymer, that is, the mixed liquid 93 sent out from the first separation device 13, has the pH maintained within a predetermined range, and is separated into the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer and the other materials (foreign matter) using a sieve. As a result, the pulp fibers, the superabsorbent polymer, and the acidic aqueous solution (part of which includes other materials and the like) in the mixed liquid 93 are separated by the sieve and are sent out from the first dust removal device 14 (mixed liquid 94). On the other hand, the other materials in the mixed liquid 93 other than the pulp fibers, the superabsorbent polymer, and the acidic aqueous solution cannot pass through the sieve and remain in the first dust removal device 14 or are sent out through other paths. Among them, part of the other materials cannot be completely separated and are sent out together with the mixed liquid 94.

[0124] Note that the acidic aqueous solution is preferably adjusted in pH so that the difference between the specific gravity of the superabsorbent polymer and the specific gravity of the pulp fiber and the difference between the size of the superabsorbent polymer and the size of the pulp fiber are within a predetermined range, at least before the first dust removal step S14. The predetermined range is, for example, a range of 0.2 to 5 times one of the other. In this case, the process before the first dust removal step S14 can be considered as a deactivation step in which the pulp fiber and the superabsorbent polymer are mixed with the acidic aqueous solution adjusted in pH so that the difference between the specific gravity of the superabsorbent polymer and the specific gravity of the pulp fiber and the difference between the size of the superabsorbent polymer and the size of the pulp fiber are within a predetermined range, thereby deactivating the superabsorbent polymer.

[0125] In addition, the concentration of the pulp fiber and the superabsorbent polymer combined in the acidic solution in the first dust removal step S14 is, for example, 0.1% by mass or more and 10% by mass or less, and is preferably 0.1% by mass or more and 5% by mass or less. In addition, the ratio of the pulp fiber to the superabsorbent polymer in the acidic solution is, for example, 50% by mass to 90% by mass: 50% by mass to 10% by mass.

[0126] The second dust removal step S15 is performed using the second dust removal device 15, and the acidic aqueous solution containing the pulp fiber and the superabsorbent polymer, that is, the mixed solution 94, which is sent out from the first dust removal device 14, is maintained in pH within a predetermined range while being separated into the acidic aqueous solution containing the pulp fiber and the superabsorbent polymer and other materials (foreign matter) by sieving. As a result, the pulp fiber, the superabsorbent polymer, and the acidic aqueous solution (part of which includes other materials and the like) in the mixed solution 94 are separated by the sieve and are sent out from the second dust removal device 15 (mixed solution 95). On the other hand, the other materials in the mixed solution 94, other than the pulp fiber, the superabsorbent polymer, and the acidic aqueous solution, are left in the second dust removal device 15 without passing through the sieve or are sent out through other paths. Among them, part of the other materials cannot be completely separated and are sent out together with the mixed solution 95. Note that the acidic aqueous solution is adjusted in pH so that the difference between the specific gravity of the superabsorbent polymer and the specific gravity of the pulp fiber and the difference between the size of the superabsorbent polymer and the size of the pulp fiber are within a predetermined range.

[0127] The third dust removing process S16 is performed by the third dust removing device 16 to maintain the pH value of the mixed solution 95, which is the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer sent from the second dust removing device 15, within a predetermined range while being centrifugally separated in the inverted conical housing, into the pulp fibers and the superabsorbent polymer in the acidic aqueous solution and other materials (heavy foreign matter). As a result, the pulp fibers, the superabsorbent polymer, and the acidic aqueous solution in the mixed solution 95 are sent from the upper portion of the third dust removing device 16 (cyclone) as the mixed solution 96. On the other hand, the other materials heavier than the pulp fibers, the superabsorbent polymer, and the acidic aqueous solution in the mixed solution 95 are sent from the lower portion of the third dust removing device 16 (cyclone). Note that the pH value of the acidic aqueous solution is adjusted so that the difference between the specific gravity of the superabsorbent polymer and the specific gravity of the pulp fibers and the difference between the size of the superabsorbent polymer and the size of the pulp fibers are within a predetermined range.

[0128] The present method (system) includes at least the second dust removing process S15 (the second dust removing device 15) and the third dust removing process S16 (the third dust removing device 16) in the dust removing processes (the first dust removing process S14 (the first dust removing device 14) to the third dust removing process S16 (the third dust removing device 16)) for removing foreign matter (other materials). Thus, the pulp fibers and the superabsorbent polymer can be easily separated from the other materials of the used absorbent article other than the pulp fibers and the superabsorbent polymer, mainly resin materials (the second dust removing process S15 (the second dust removing device 15)), and easily separated from the materials heavier than the other materials, for example, metal materials (the third dust removing process S16 (the third dust removing device 16)) in terms of specific gravity. Moreover, the pulp fibers and the superabsorbent polymer can be recovered from the used absorbent article by separating the pulp fibers and the superabsorbent polymer from each other (the second separation process S17, the third separation process S18 (the second separation device 17, the third separation device 18)). At this time, the number of times of the processes for separating the pulp fibers and the superabsorbent polymer from the other materials can be reduced. That is, the efficiency of the processes for separating the superabsorbent polymer and the pulp fibers can be improved.

[0129] The second separation process S17 is performed using the second separation device 17. The acidic aqueous solution containing pulp fibers and superabsorbent polymers, i.e., the mixed liquid 96, which is sent out from the third dust removal device 16, is separated into pulp fibers in an acidic aqueous solution and superabsorbent polymers in an acidic aqueous solution using a drum sieve. As a result, the acidic aqueous solution containing superabsorbent polymers is separated from the mixed liquid 96 by passing through the drum sieve 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 drum sieve and is sent out from the second separation device 17 through another path (mixed liquid 97). Note that, thereafter, the superabsorbent polymers can be separated from the separated superabsorbent polymers and acidic aqueous solution using a sieve separator or the like. Thus, the above process can be referred to as a process of separating / recovering superabsorbent polymers, and a process of generating recycled superabsorbent polymers therefrom.

[0130] The third separation process S18 is performed using the third separation device 18. The pulp fibers, superabsorbent polymers that cannot be separated and remain, and the acidic aqueous solution, i.e., the mixed liquid 97, which is sent out from the second separation device 17, are separated into solids containing pulp fibers and superabsorbent polymers and liquids containing superabsorbent polymers and acidic aqueous solution using a drum sieve. Then, while being separated, the superabsorbent polymers in the solids are crushed by pressure. The crushing is exemplified by crushing the gel-like superabsorbent polymers at a pressure of a gel strength or more. As a result, the acidic aqueous solution containing superabsorbent polymers is separated from the mixed liquid 97 by passing through the drum sieve and is sent out from the third separation device 18. On the other hand, the pulp fibers in the mixed liquid 97, which are crushed by the superabsorbent polymers, cannot pass through the drum sieve and are sent out to the outside of the third separation device 18 from the gap of the cover of the top end portion of the drum sieve (mixture 98). The pressure of the pressing applied to the cover is, for example, 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 superabsorbent polymers, and it is not possible to excessively shorten the time of the oxidizing agent treatment, and if the pressure is greater than 0.5 MPa, although the superabsorbent polymers are sufficiently crushed, it is possible that the pulp fibers are damaged.

[0131] The oxidant treatment step S19 is performed using an oxidant treatment device 19. The pulp fibers and the crushed superabsorbent polymer in the solid discharged from the third separation device 18 are treated in an aqueous solution containing an oxidant. Thereby, the superabsorbent polymer is oxidatively decomposed and removed from the pulp fibers. As a result, the superabsorbent polymer adhered to the pulp fibers (example: remaining on the surface of the pulp fibers) of the mixture 98 is oxidatively decomposed using an aqueous solution (treatment liquid) containing an oxidant (example: ozone), and removed from the pulp fibers by becoming a low-molecular-weight organic substance that is soluble in the aqueous solution. Here, the state in which the superabsorbent polymer is oxidatively decomposed and becomes a low-molecular-weight organic substance that is soluble in the aqueous solution refers to a state in which the superabsorbent polymer passes through a 2-mm sieve. Thereby, the superabsorbent polymer and other impurities contained in the pulp fibers can be removed, and pulp fibers with a high degree of purity can be produced, and sterilization, bleaching, and deodorization of the pulp fibers can be performed by the oxidant treatment.

[0132] For example, in the oxidant treatment device 19, the mixture 98 is dropped from the upper portion of the treatment tank, and gradually settles from the upper portion toward the lower portion of the treatment liquid, that is, the aqueous solution containing the oxidant. On the other hand, the ozone-containing gas is continuously released from the nozzles in the treatment tank into the treatment liquid in the form of fine bubbles (example: micron bubbles or nanobubbles). That is, the ozone-containing gas gradually rises from the lower portion toward the upper portion of the treatment liquid. In the treatment liquid, the settled pulp fibers and the rising ozone-containing gas advance in opposite directions and collide with each other. Then, the ozone-containing gas adheres to the surface of the pulp fibers in a manner in which the pulp fibers are wrapped. At this time, the ozone in the ozone-containing gas reacts with the superabsorbent polymer in the pulp fibers, oxidatively decomposes the superabsorbent polymer, and dissolves the superabsorbent polymer in the treatment liquid. Thereby, the superabsorbent polymer contained in the pulp fibers of the mixture 98 is oxidatively decomposed and removed from the pulp fibers.

[0133] The fourth separation step S20 is performed using a fourth separation device 20, and the treatment liquid containing the pulp fibers, that is, the mixture 99 treated in the oxidant treatment device 19 is separated into the pulp fibers and the treatment liquid from the mixture 99 by a sieve having a plurality of slits. As a result, the treatment liquid 104 is separated from the mixture 99 by passing through the sieve and is discharged from the fourth separation device 20. The separated treatment liquid 104, that is, the oxidant treatment liquid can also be returned to the oxidant treatment device 19 and reused. The cost of the oxidant treatment liquid can be reduced. On the other hand, the pulp fibers in the mixture 99 cannot pass through the sieve and remain in the fourth separation device 20 or are discharged through another path. The above process can also be referred to as a process for separating / recovering pulp fibers, and thereby a process for producing recycled pulp fibers.

[0134] The present method (system) includes at least the third separation step S18 (third separation device 18) and the oxidizing agent treatment step S19 (oxidizing agent treatment device 19) in the recycling process (second separation step S17 (second separation device 17) to fourth separation step S20 (fourth separation device 20)) of recycling pulp fibers and the like as described above. Thus, by crushing the substantially spherical or block-shaped superabsorbent polymer, the surface area of the superabsorbent polymer can be greatly expanded, and the exposed portion of the inside of the superabsorbent polymer can be increased. Therefore, in the oxidizing agent treatment step S19 (oxidizing agent treatment device 19), in the case of the block-shaped or substantially spherical superabsorbent polymer, the inside of the superabsorbent polymer that is difficult to contact with the oxidizing agent can be brought into contact with the oxidizing agent, and the contact area of the superabsorbent polymer with the oxidizing agent can be increased. Thus, the oxidative decomposition of the superabsorbent polymer can be more efficiently performed, and the time of the oxidizing agent treatment can be shortened. Therefore, the efficiency of the process of removing the superabsorbent polymer from the pulp fibers can be improved.

[0135] The crushing process is preferably performed in batch processing. The collection bag A of one batch amount in the volume tank V (Va) and the acidic aqueous solution B are both drawn from the solution tank V (Va) via the crushing portion 60 using the pump 63. At this time, the used absorbent article is crushed by the crushing portion 60 together with the collection bag A halfway. In this case, the liquid crushing step and the drawing step are continuously and simultaneously performed at once.

[0136] Note that the method preferably includes the ozone treatment step S22 and the pH adjustment step S23. These steps are steps for regenerating the acidic aqueous solution used in the method and recycling it. By recycling the acidic aqueous solution, the cost of the acidic aqueous solution can be reduced. The ozone treatment step S22 performs sterilization treatment on the acidic aqueous solution 101 after the superabsorbent polymer is further separated from the superabsorbent polymer and the acidic aqueous solution after the separation in the second separation step S17 using an ozone-containing aqueous solution. The pH adjustment step S23 adjusts the pH of the acidic aqueous solution 102 subjected to the sterilization treatment using the ozone-containing aqueous solution to generate a regenerated acidic aqueous solution 103. The acidic aqueous solution 103 is supplied to the crushing device 11, for example, and the acidic aqueous solution can also be supplied to other processes (devices) as needed. The remaining portion of the acidic aqueous solution 103 is stored in the water storage tank 24.

[0137] In the above-described method for recovering pulp fibers from used absorbent articles containing self-contained pulp fibers and superabsorbent polymers, at least the hole opening step SIl (bag breaking device 11) and the crushing step S12 (crushing device 12) are included in the crushing process (the hole opening step SIl (bag breaking device 11) to the first separation step S13 (first separation device 13)) of crushing the used absorbent articles. Also, in the hole opening step SIl (bag breaking device 11), the hole is opened in the collection bag, and thus the inactivation aqueous solution (example: acidic aqueous solution) is introduced from the hole into the collection bag, the superabsorbent polymers contained in the used absorbent articles are inactivated with the inactivation aqueous solution, and the collection bag is caused to substantially sink below the water surface of the inactivation aqueous solution. Next, in the crushing step S12 (crushing device 12), the collection bag that has sunk below the water surface of the inactivation aqueous solution is discharged from the solution tank together with the inactivation aqueous solution, and at the same time, the used absorbent articles are crushed in the inactivation aqueous solution together with the collection bag. Thus, the used absorbent articles in the state of being put into the collection bag are crushed in the inactivation aqueous solution together with the collection bag, and thus the inactivation aqueous solution is hardly mixed with dirt, bacteria, or odor is hardly generated at least until the crushing is started. Also, even if the inactivation aqueous solution is mixed with dirt, bacteria, or odor is generated when the used absorbent articles are crushed, since the inactivation aqueous solution mixed with the dirt and bacteria is discharged from the solution tank together with the crushed materials at substantially the same time as the crushing, the dirt and bacteria hardly remain in the solution tank. In addition, the odor can be sealed with the inactivation aqueous solution, and thus the generation of odor can also be suppressed to be low. Thus, when the used absorbent articles are crushed, the scattering of dirt, bacteria, or the release of odor accompanying the generation of the dirt can be suppressed. That is, the used absorbent articles can be crushed hygienically and safely, and the cost of hygiene management of the operation and maintenance can be suppressed.

[0138] As a preferred mode of the embodiment, the step of opening a hole in the collection bag of the hole opening step SIl and the step of crushing the used absorbent articles together with the collection bag of the crushing step S12 can be performed at different positions.

[0139] In the present method, the step of opening a hole in the collection bag (bag breaking device 11) and the step of crushing the used absorbent articles together with the collection bag (crushing device 12) are performed at different positions or locations (devices). Therefore, after the inactivation aqueous solution is introduced from the hole into the collection bag and the collection bag is reliably caused to sink below the water surface of the inactivation aqueous solution, the crushing can be performed at different positions or locations. Thus, when the crushing is performed, the part of the collection bag can be suppressed from being exposed on the water surface of the inactivation aqueous solution, the opening (crack) of the hole can be suppressed from being exposed on the water surface of the inactivation aqueous solution, and thus the scattering of dirt, bacteria, or the release of odor accompanying the generation of the dirt of the used diaper can be suppressed.

[0140] As a preferred form of the embodiment, the crushing process S12 (crushing device 12) can also include a liquid crushing process (crushing section 60) that crushes the used absorbent articles in the collection bag together with the collection bag in the inactivation aqueous solution and a extraction process (pump 63) that extracts the crushed matter obtained by the liquid crushing process (crushing section 60) together with the inactivation aqueous solution from the liquid crushing process (crushing section 60).

[0141] In the present method, by actively discharging the mixture 92 of the crushed matter and the inactivation aqueous solution from the liquid crushing process (crushing section 60), the dirt of the equipment related to the liquid crushing process (crushing section 60) can be removed (flowed away) using the inactivation aqueous solution in conjunction with the movement of the mixture 92. Thus, the sanitary state of the crushing process (crushing device 12) can be kept well.

[0142] Here, it is preferable that the crushing section be present below compared to the solution tank in the vertical direction. Thus, the mixture 92 can also be actively discharged from the liquid crushing process (crushing section 60) using the gravity. Thus, the dirt of the equipment related to the liquid crushing process (crushing section 60) can be more reliably removed (flowed away) using the inactivation aqueous solution in conjunction with the movement of the mixture 92.

[0143] As a preferred form of the embodiment, the crushing process S12 (crushing device 12) can also include a process that crushes the used absorbent articles together with the collection bag so that the average value of the size of the crushed matter is 50 mm or more and 100 mm or less.

[0144] In the present method, in the crushing process S12 (crushing device 12), the crushing device 12 is adjusted so that the average value of the size of the crushed matter is 50 mm or more and 100 mm or less. In this case, the slitting can be reliably formed on the back sheet and / or the surface sheet of each used absorbent article, and thus the pulp fibers can be substantially free of residues from the slitting and extracted from each used absorbent article. Thus, the recovery rate of the pulp fibers and the superabsorbent polymer can be improved. If the average value of the size is less than 50 mm, other materials (examples: films, nonwoven fabrics, elastomers, and the like) other than the pulp fibers and the superabsorbent polymer are excessively cut, and it is difficult to separate the other materials from the pulp fibers and the superabsorbent polymer. As a result, the other materials mixed into the regenerated pulp fibers and the superabsorbent polymer increase, and the recovery rate of the pulp fibers decreases. On the other hand, if the average value of the size is more than 100 mm, it is difficult to form the slitting on the used absorbent article. As a result, the used absorbent article from which the pulp fibers and the superabsorbent polymer cannot be extracted increases, and the recovery rate of the pulp fibers and the superabsorbent polymer decreases.

[0145] As a preferred mode of the embodiment, the process of crushing the used absorbent article together with the collection bag in the inactivation aqueous solution in the crushing process S12 (crushing device 12) can also be performed by a double shaft crusher (the crushing section 60 can also include a double shaft crusher).

[0146] In the present method, the process of crushing the used absorbent article is performed using a double shaft crusher (the crushing section 60 includes a double shaft crusher). The double shaft crusher is exemplified by a double shaft rotary crusher, a double shaft differential crusher, and a double shaft shearing crusher. Thus, the size of the crushed product can be made uniform within a substantially predetermined range. Thereby, it is possible to suppress the crushed product from becoming too small, the foreign matter from being mixed in the pulp fiber, or the crushed product from becoming too large, the used absorbent article from which the pulp fiber cannot be taken out, and thus the recovery rate of the pulp fiber from decreasing.

[0147] As another embodiment, the process of perforating the collection bag on the surface thereof in contact with the inactivation aqueous solution in the perforating process S11 (bag breaking device 11) (perforating section 50) can also be performed using a protrusion (bag breaking blade 41 of the bag breaking section 40) that is capable of moving up and down in the solution tank V while rotating around a rotation axis.

[0148] In the present method, the collection bag is perforated using a protrusion (bag breaking blade 41) that moves up and down in the solution tank while rotating around a rotation axis. Therefore, even if the collection bag does not sink in the inactivation aqueous solution, the collection bag can be reliably perforated, for example, by moving the protrusion upward in the solution tank to contact the collection bag. Since the collection bag is made to sink in the inactivation aqueous solution after being perforated, the collection bag can be reliably sunk in the acidic solution in a short time, and the processing time can be reduced, and the processing efficiency can be improved.

[0149] As a preferred mode of the embodiment or another embodiment, the process of perforating the collection bag on the surface thereof in contact with the inactivation aqueous solution in the perforating process S11 (bag breaking device 11) (perforating section 50 or perforating section 50a) can also be performed by feeding the collection bag from the upper portion of the solution tank Va into the inactivation aqueous solution to contact a protrusion (bag breaking blade 41 of the bag breaking section 40, protruding portion 44 of the rotary rotor 41a of the bag breaking section 40a) disposed in the lower portion of the solution tank Va and rotating around a rotation axis.

[0150] In the present method, the collection bag is sent into the inactivation aqueous solution, and a hole is punched in the collection bag by a protrusion (punching knife 41 of the bag breaking portion 40, protruding portion 44 of the rotating rotor 41a of the bag breaking portion 40a) of the lower portion of the solution tank Va. Since the hole is punched after the collection bag is settled in the inactivation aqueous solution, it is possible to reliably prevent the spread of dirt and odor from the used absorbent article in the collection bag to the outside. Thus, it is possible to more hygienically and safely crush the used absorbent article.

[0151] As a preferred mode of the embodiment, the inactivation aqueous solution is an acidic aqueous solution.

[0152] In the present method, the inactivation aqueous solution is an acidic aqueous solution, and thus it is possible to reliably dehydrate and inactivate the superabsorbent polymer in the used absorbent article. In particular, when crushing is performed in an acidic aqueous solution, alkaline volatile components derived from excrement such as urine do not volatilize but remain in the acidic aqueous solution, and thus it is possible to suppress the generation of odor due to alkaline gas such as ammonia. Thus, in the crushing step S12 (crushing device 12), the used absorbent article does not greatly expand, and it is possible to easily perform crushing, and it is possible to improve the processing efficiency.

[0153] As a preferred mode of the embodiment, the acidic aqueous solution contains citric acid.

[0154] In the present method, the acidic aqueous solution contains citric acid (example: concentration 0.5 mass% to 2.0 mass%), and thus it is possible to dehydrate and inactivate the superabsorbent polymer in the used absorbent article, and there is almost no adverse effect of the acid on the workers, and it is also possible to suppress the corrosion of the equipment of each step by the acid.

[0155] (2nd Embodiment)

[0156] The 2nd embodiment will be described. Hereinafter, mainly the differences from the 1st embodiment will be described. In the present embodiment as well, a case in which an acidic aqueous solution is used as the inactivation aqueous solution will be described as an example.

[0157] A system 1 used in a method of recycling pulp fibers from a used absorbent article will be described. FIG. 6 is a block diagram showing an example of the system 1 of the present embodiment. The system 1 of the present embodiment includes a container (not shown), a crushing device 12, and a 1st separation device 13, and preferably includes a 1st dust removal device 14, a 2nd dust removal device 15, a 3rd dust removal device 16, a 2nd separation device 17, a 3rd separation device 18, an oxidizing agent treatment device 19, and a 4th separation device 20. Hereinafter, a detailed description will be given.

[0158] In the present embodiment, the container (not shown), the crushing device 12, and the first separation device 13 are integrated to configure the crushing and separation device 10. That is, the system 1 includes the crushing and separation device 10. Here, the container is a container into which the collection bag A in which the used absorbent article is enclosed is put. The crushing device 12 communicates with the container, and crushes the used absorbent article in the collection bag A together with the collection bag A in the acidic aqueous solution B while the collection bag A in the container is moved. The first separation device 13 separates the pulp fiber, the superabsorbent polymer, and the inactivated aqueous solution from the crushed matter and the acidic aqueous solution B obtained by the crushing device 12.

[0159] FIG. 7 is a schematic view of a configuration example of the crushing and separation device 10 (container + crushing device 12 + first separation device 13) of FIG. 6 . The container 65 is installed at the upper portion of the crushing device 12, is open at the top, or is provided with an openable and closable lid, and is capable of putting the collection bag A into the inside from the top. In addition, the container 65 is joined at the side surface with a pipe 66 provided with a valve (not shown), and is capable of supplying the acidic aqueous solution B (may also be the regenerated acidic aqueous solution 103) from the pipe 66. In addition, the lower portion of the container 65 communicates with the upper portion of the crushing device 12, and supplies the acidic aqueous solution B supplied via the pipe 66 along the inner wall surface to the crushing device 12, and is capable of supplying the collection bag A in the inside to the crushing device 12. The container 65 can also be considered as a form in which the acidic aqueous solution B is not stored in the solution tank V of the first embodiment at all times.

[0160] In the crushing device 12, the crushing portion 60 (refer to FIG. 4The acidic aqueous solution B is stored in the interior of the container 65 in such a manner as to cover the rotating shafts 72, the pads 73, and the rotary knives 74 of the crushing portion 60, for example. The liquid surface is at least the position of the upper end of the rotary knives 74, and preferably at the position of the boundary between the container 65 and the crushing device 12. The height of the liquid surface is measured, for example, with a liquid level gauge. If the collection bag A reaches the bottom of the container 65, at least a portion of the collection bag A is supplied into the acidic aqueous solution B in the crushing device 12, and the collection bag A is pulled into the crushing portion 60 by the rotation of the rotary knives 74 and the pads 73 of the pair of rotating shafts 72, 72 of the crushing portion 60. Thus, the crushing device 12 crushes the used absorbent article in the collection bag A together with the collection bag A in the acidic aqueous solution B. The crushing device 12 is connected to the first separation device 13 disposed directly below the crushing portion 60 of the crushing device 12 via the pipe 62. The crushing device 12 sends out the crushed material obtained by the crushing portion 60 together with the acidic aqueous solution B (mixed liquid 92) to the first separation device 13 via the pipe 62. Note that the acidic aqueous solution B that is insufficient in the sending out of the mixed liquid 92 can be supplied from the container 65, from a pipe (not shown) directly connected to the crushing device 12, or from the first separation device 13.

[0161] The first separation device 13, which is filled with the acidic aqueous solution B, stirs the mixed liquid 92 containing the crushed material and the acidic aqueous solution B obtained by the crushing device 12, separates the pulp fibers, the superabsorbent polymer, and the acidic aqueous solution from the mixed liquid 92 (mixed liquid 93), and sends it out to the first dust removal device 14. Specifically, the first separation device 13 includes a container 80, an impeller 81, a screen 82, a side chamber 83, and a lower surface valve 84. The container 80 is used to store the mixed liquid 92. The impeller 81 stirs the mixed liquid 92 and directs it toward the screen 82. The screen 82 is a sieve having a plurality of openings. The plurality of openings are sized to allow the pulp fibers and the superabsorbent polymer in the crushed material in the mixed liquid 92 to pass through easily, and other materials to pass through with difficulty. The side chamber 83 sends out the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer (mixed liquid 93) that has passed through the screen 82. The lower surface valve 84 is opened when other materials (foreign matter) that cannot pass through the screen 82 are removed from the container 80. The first separation device 13 can be exemplified by a packaging pulper (manufactured by Satomi Mfg. Co., Ltd.), for example.

[0162] Next, a method for recovering pulp fibers from used absorbent articles will be described. This method is a method for recovering pulp fibers (and preferably also superabsorbent polymers) from used absorbent articles, thereby producing recycled pulp fibers (and preferably also recycled superabsorbent polymers). FIG. 8is a flowchart showing an example of the method of the present embodiment. The method includes the crushing step S12 and the first separation step S13, and preferably includes the first dust removal step S14, the second dust removal step S15, the third dust removal step S16, the second separation step S17, the third separation step S18, the oxidizing agent treatment step S19, and the fourth separation step S20. Hereinafter, the details will be described. The method of the present embodiment can be considered as the method of the first embodiment except for the opening step S11.

[0163] The crushing step S12 is performed using the container 65 and the crushing device 12 of the crushing separation apparatus 10. The acidic aqueous solution B is supplied to the container 65 as necessary via the pipe 66 so that the height of the liquid surface of the acidic aqueous solution B of the crushing device 12 becomes a predetermined height, and the inner wall surface is removed of dirt while being supplied to the crushing device 12 along the inner wall surface.

[0164] The collection bag A is placed in the container 65 so as to reach the bottom of the container 65, and at least a part of the collection bag A is supplied to the acidic aqueous solution B in the crushing device 12. Then, the collection bag A is pulled into the acidic aqueous solution B in the crushing portion 60 by the rotation of the pair of rotating shafts 72, 72, the rotating blade 74, and the gasket 73 of the crushing portion 60. As a result, the used absorbent articles in the collection bag A are crushed together with the collection bag A in the acidic aqueous solution B by the crushing portion 60. Note that in the present embodiment, the average value of the size of the crushed matter is also preferably 50 mm or more and 100 mm or less.

[0165] The mixed liquid 92 containing the crushed matter and the acidic aqueous solution B, which is discharged from the crushing portion 60, is supplied to the first separation device 13 disposed directly below the crushing device 12 (the crushing portion 60) via the pipe 62.

[0166] The first separation step S13 is performed using the first separation device 13 of the crushing separation apparatus 10. The container 80 of the first separation device 13 is filled with the acidic aqueous solution B by supplying the acidic aqueous solution B (including the mixed liquid 92) from the crushing device 12.

[0167] The mixture 92 including the crushed material and the acidic aqueous solution B is stirred in the container 80 by the impeller 81, and is washed to remove dirt from the crushed material while being guided toward the sieve plate 82. Then, the mixture 92 is separated into the pulp fibers, the superabsorbent polymer, and the acidic aqueous solution and other materials by the sieve plate 82. That is, the pulp fibers and the superabsorbent polymer in the crushed material in the mixture 92 pass through the sieve plate 82 to be separated into the side chamber 83, and the other materials do not pass through the sieve plate 82 to remain in the container 80. The pulp fibers, the superabsorbent polymer, and the acidic aqueous solution B (mixture 93) that have reached the side chamber 83 are sent to the first dust removing device 14 via a pipe. A part of the other materials that cannot be completely separated is sent together with the mixture 93. The size of the opening of the sieve as the first separating device 13 is 5 mm to 20 mm φ in the case of a circular opening, and is substantially the same size as the area of a circular opening in the case of an opening of another shape.

[0168] In the present system and method, after the collection bag A is housed in the container 65, the collection bag A is transferred to the crushing device 12 that is provided independently of the container 65, and in the crushing device 12, the superabsorbent polymer of the used absorbent article in the collection bag A is inactivated in the acidic aqueous solution B (inactivation aqueous solution) while the used absorbent article is crushed together with the collection bag A. That is, when the used absorbent article is crushed, the crushing is performed in the acidic aqueous solution B in the crushing device 12 that is independent of the container 65, and after the crushing, the acidic aqueous solution B and the crushed material are sent to the first separating device 13. Therefore, even if dirt, bacteria, or odor is mixed in the acidic aqueous solution B, the acidic aqueous solution B in which the dirt, the bacteria, or the odor is mixed and the crushed material hardly reach the container 65. Therefore, the crushing can be performed almost without leaving the dirt, the bacteria, or the odor in the container. Further, the odor can be sealed by the acidic aqueous solution B, and thus the generation of the odor can also be suppressed to be low. In particular, if the crushing is performed in the acidic aqueous solution B, alkaline volatile components derived from the excrement such as urine do not volatilize but remain in the acidic aqueous solution B, and thus the generation of the odor due to the alkaline gas such as ammonia can be suppressed. Thus, when the used absorbent article is crushed, the scattering of the dirt, the bacteria, or the odor, or the release of the odor accompanying the dirt can be suppressed. That is, the used absorbent article can be crushed hygienically and safely, and the cost of the hygiene management of the operation and the maintenance can be suppressed.

[0169] Embodiment

[0170] An embodiment of the method for recovering pulp fibers from a used absorbent article described above will be described below.

[0171] In the present embodiment, the opening process S11, the crushing process S12, and the first separation process S13 of the method of the first embodiment described above are performed on the absorbent article, and the relationship between the crushing method and the amount of mixing of other materials (foreign matter) is investigated. Specifically, as the absorbent article, a disposable diaper for adults (unused) is used. In the crushing process S12, the disposable diaper at the time when the crushing device 12 is adjusted in such a manner that the average value of the size of the crushed matter becomes 25 mm, 50 mm, and 100 mm, respectively, is set as Examples 1 to 3. On the other hand, the disposable diaper on which the crushing process S12 is not performed is set as Comparative Example.

[0172] In FIG. 9 the results of investigating the relationship between the crushing method and the amount of mixing of other materials are shown. FIG. 9 is a graph showing the relationship between the size of the crushed matter in the crushing process and the amount of processing and the amount of foreign matter. The bar graph (the vertical axis is the left axis) shows the amount of processing (kg) per 1 batch, which indicates the amount of the disposable diaper that can be processed by the first separation device 13 of the first separation process S13. The line graph (the vertical axis is the right axis) shows the proportion (%) of foreign matter (other materials) other than the pulp fiber and the superabsorbent polymer included in the mixed liquid 93 (the acidic aqueous solution containing the pulp fiber and the absorbent polymer after separation) after the first separation process S13.

[0173] In the case where the crushing is not performed (Comparative Example), the disposable diaper is directly processed with the first separation process S13. Therefore, as shown in the graph, the amount of the disposable diaper that can be processed by the first separation device 13, that is, the amount of the disposable diaper from which the pulp fiber and the superabsorbent polymer can be extracted (the amount of processing) is small, because the disposable diaper becomes large, becomes fluffy, or the combination of the surface sheet and the back sheet is difficult to be removed, and the like. Among them, since it is not crushed, the size of each material is large, and the amount of foreign matter included in the mixed liquid 93 after the first separation process S13 is small.

[0174] On the other hand, in the case where the crushing is performed (Examples), the disposable diaper is not fluffy, and the amount of the disposable diaper that can be processed by the first separation device 13 (the amount of processing) becomes large. Among them, by crushing, each material becomes small, and the amount of foreign matter included in the mixed liquid 93 after the first separation process S13 becomes large.

[0175] Thus, it is found that, from the viewpoint of the amount of processing, the crushing is better than the non-crushing. Also, it is found that, in the case where the viewpoint of the amount of foreign matter is also considered, it is preferable that the average value of the size of the crushed matter be 50 mm or more and 100 mm or less.

[0176] The above-described embodiments have been described in the case where the structural member of the back sheet is a film and the structural member of the surface sheet is a nonwoven fabric. However, embodiments in the case where the structural member of the back sheet is a nonwoven fabric and the structural member of the surface sheet is a film, the case where the structural members of both the back sheet and the surface sheet are films can also be implemented in the same manner as the above-described embodiments, and the same effects can be produced.

[0177] The absorbent article of the present application is not limited to the above-described embodiments, and the technology of each of the embodiments, other technologies, and the like can be appropriately combined, changed, and the like within a range not departing from the object, the gist of the present application, and not producing technical contradictions.

[0178] Explanation of Reference Numerals

[0179] A, collection bag

[0180] V, solution tank

[0181] S11, hole opening process

[0182] S12, breaking process

[0183] S13, first separation process

Claims

1. A method of recovering pulp fibers from used absorbent articles containing pulp fibers and superabsorbent polymers, wherein the method comprises: a receiving step in which a collection bag enclosing a used absorbent article is put into a container that does not store an inactivated aqueous solution at all times; a breaking step in which the collection bag in the container is transferred to a breaking device storing the inactivated aqueous solution in communication with the container, while the used absorbent article in the collection bag is broken together with the collection bag in the inactivated aqueous solution using the breaking device, the container that does not store the inactivated aqueous solution at all times is side-joined to a pipe equipped with a valve, can supply the inactivated aqueous solution from the pipe, and the lower portion of the container is in communication with the upper portion of the breaking device, the inactivated aqueous solution supplied through the pipe is transported along the inner wall surface to be supplied to the breaking device; a sending-out step in which the broken matter obtained by breaking is sent out from the breaking device to a first separation device together with the inactivated aqueous solution; and a first separation step in which pulp fibers, superabsorbent polymers, and the inactivated aqueous solution are separated from the broken matter and the inactivated aqueous solution using the first separation device, in the first separation step, a mixed liquid containing the broken matter and the inactivated aqueous solution is stirred in the container using an impeller, cleaning to remove dirt from the broken matter is performed, and then the mixed liquid is separated into pulp fibers, superabsorbent polymers, and the inactivated aqueous solution and other materials using a sieve plate, wherein the inactivated aqueous solution is an acidic aqueous solution. the first separation step includes a step of directly receiving the broken matter and the inactivated aqueous solution using the first separation device disposed directly below the breaking device.

2. The method of claim 1, wherein, the breaking step includes a step of breaking the used absorbent article together with the collection bag so that the average value of the size of the broken matter is 50 mm or more and 100 mm or less.

3. The method of claim 1 or 2, wherein, the step of breaking the used absorbent article together with the collection bag in the inactivated aqueous solution in the breaking step is performed using a double shaft crusher.

4. The method of claim 1 or 2, wherein, the acidic aqueous solution contains citric acid.

5. The method of claim 1, wherein, 6. A system used in a method of recovering pulp fibers from used absorbent articles containing pulp fibers and superabsorbent polymers, wherein the system comprises: a container into which a collection bag enclosing a used absorbent article is put, and the container does not store an inactivated aqueous solution at all times; a breaking device in communication with the container and storing an inactivated aqueous solution, which breaks the used absorbent article in the collection bag together with the collection bag in the inactivated aqueous solution while transferring the collection bag in the container, the container that does not store the inactivated aqueous solution at all times is side-joined to a pipe equipped with a valve, can supply the inactivated aqueous solution from the pipe, and the lower portion of the container is in communication with the upper portion of the breaking device, the inactivated aqueous solution supplied through the pipe is transported along the inner wall surface to be supplied to the breaking device; and ​ ​ a first separation device that separates pulp fibers, a superabsorbent polymer, and the inactivated aqueous solution from the crushed matter and the inactivated aqueous solution obtained by the crushing device and sent out from the crushing device, the first separation device includes a container that stores a mixed liquid, an impeller that stirs the mixed liquid and directs it toward a screen plate, and the screen plate is a screen having a plurality of openings sized to allow the pulp fibers and the superabsorbent polymer in the crushed matter in the mixed liquid to pass through easily and other materials to pass through with difficulty, wherein the inactivated aqueous solution is an acidic aqueous solution.

7. The system of claim 6, wherein, The first separation device is disposed directly below the crushing device and receives the crushed matter and the inactivated aqueous solution directly from the crushing device.

8. The system of claim 6 or 7, wherein, The crushing device crushes the used absorbent articles together with the collection bag so that the average size of the crushed matter is 50 mm or more and 100 mm or less.

9. The system of claim 6 or 7, wherein, The crushing device includes a double-shaft crusher.

10. The system of claim 6, wherein, The acidic aqueous solution includes citric acid.

11. A method of crushing used absorbent articles placed in a collection bag, wherein the method includes: a receiving step in which a collection bag enclosing used absorbent articles is placed in a container that does not store an inactivated aqueous solution at all times; a crushing step in which the collection bag in the container is transferred to a crushing device storing the inactivated aqueous solution in communication with the container, while the used absorbent articles in the collection bag together with the collection bag are crushed in the inactivated aqueous solution using the crushing device, the container having a pipe with a valve joined to a side surface, capable of supplying the inactivated aqueous solution from the pipe, and the lower portion of the container being in communication with the upper portion of the crushing device, the inactivated aqueous solution supplied through the pipe being transported along the inner wall surface to be supplied to the crushing device; a sending-out step in which the crushed matter obtained by crushing is sent out from the crushing device together with the inactivated aqueous solution to a first separation device; and a first separation step in which the first separation device separates pulp fibers, a superabsorbent polymer, and the inactivated aqueous solution from the crushed matter and the inactivated aqueous solution, wherein the mixed liquid containing the crushed matter and the acidic aqueous solution is stirred in the container using an impeller, washed to remove dirt from the crushed matter, and directed toward a screen plate, and then separated into pulp fibers, a superabsorbent polymer, and the acidic aqueous solution and other materials using the screen plate, wherein the inactivated aqueous solution is an acidic aqueous solution.

12. A system used in a method of crushing used absorbent articles placed in a collection bag, wherein the system includes: a container that places a collection bag enclosing used absorbent articles, and the container does not store an inactivated aqueous solution at all times; a crushing device that crushes the used absorbent articles together with the collection bag so that the average size of the crushed matter is 50 mm or more and 100 mm or less; A breaking device which communicates with the container and stores the inactivation aqueous solution, breaks the used absorbent article in the collection bag together with the collection bag in the inactivation aqueous solution while transferring the collection bag in the container, and a container which always stores the inactivation aqueous solution is joined on the side with a pipe having a valve, can supply the inactivation aqueous solution from the pipe, and the lower portion of the container communicates with the upper portion of the breaking device, and the inactivation aqueous solution supplied via the pipe is transported along the inner wall surface to supply the breaking device; and A first separation device which separates pulp fibers, a superabsorbent polymer, and the inactivation aqueous solution from the broken matter obtained by the breaking device and the inactivation aqueous solution sent out from the breaking device, The first separation device includes a container for storing a mixed solution, an impeller which stirs the mixed solution and directs it toward a screen plate, the screen plate being a screen having a plurality of openings sized to allow pulp fibers and superabsorbent polymers in the broken matter in the mixed solution to pass easily, and other materials to pass with difficulty, The inactivation aqueous solution is an acidic aqueous solution.

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