JP2009057645A - Recycled pulp and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of easily manufacturing recycled pulp from a plaster board used paper having not been recycled, by effectively removing gypsum residue and waste construction materials, and recycled pulp manufactured by the method, which is, for example, suitable for making paper for an exterior liner and a core. <P>SOLUTION: In this manufacturing method of a recycled pulp, a used paper material, at least mainly composed of the plaster board used paper, is pulped in a pulping step, and a recycled pulp material containing gypsum is obtained in the pulping step, then the recycled pulp material containing gypsum is refined in a refining step mainly by a treatment with a cleaner, and the refined product from the refining step is dehydrated and concentrated in a dehydration and concentration step, so that this recycled pulp is obtained by this manufacturing method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to waste paper pulp and a method for producing the same. More specifically, a method for easily producing waste paper pulp at low cost while efficiently removing gypsum residue and building waste from waste paper in gypsum board and reducing the environmental load, and the method For example, it is related with the used paper pulp especially suitable for the production of, for example, exterior liners and cores.

Gypsum board is 21% (by weight) by adding water to calcined gypsum (CaSO ₄ + 1 / 2H ₂ O) to gypsum board base paper mainly made from pulp recycled from recovered paper such as newspapers and magazines. 2) gypsum, which is a two-water gypsum containing crystal water of a ratio). This gypsum board is widely used as a building material because of its excellent stability, water resistance, heat resistance, and the like, as well as excellent heat insulation and sound insulation properties, and ease of processing.

  On the other hand, a large amount of waste gypsum board is generated at the demolishing site of the house. In addition, even in new construction sites, waste gypsum board is generated in the process of processing (cutting) gypsum board into a desired shape. Conventionally, since a technology for recycling such waste gypsum board has not been established, the waste gypsum board has been landfilled as industrial waste.

  In recent years, efforts have been made to collect gypsum from waste gypsum board from the viewpoint of environmental protection and resource saving, and part of it has already been realized. For example, a method has been developed in which waste gypsum board is pulverized and the gypsum is fired after sieving to collect the calcined gypsum (hereinafter, the collected gypsum is referred to as recovered gypsum).

  However, the above method cannot solve the problem related to the treatment of the residue containing a large amount of gypsum board paper separated during sieving. That is, the residue after sieving contains a large amount of gypsum board base paper, but the surface of the gypsum board base paper is attached with needle-like crystallized gypsum and can be easily peeled off from the paper. Can not. For example, when the gypsum crystallized in a needle shape is peeled off from the paper by mechanical shearing force, the paper piece is also peeled off, which adversely affects the quality of the recovered gypsum. Therefore, it is difficult to obtain recovered gypsum using a mechanical method other than vibration sieving at the time of sieving, work efficiency is poor, and gypsum cannot be sufficiently recovered from the residue containing a large amount of gypsum board paper. .

  Then, paying attention to a chemical method instead of the mechanical method as described above, a method of chemically treating waste gypsum board and recovering pulp components has been proposed.

  For example, Patent Document 1 discloses a method in which a gypsum-paper joined body is reacted with a caustic soda aqueous solution to form a slaked lime-paper joined body, and then an aqueous acid solution is brought into contact therewith to dissolve and remove the slaked lime to recover the paper. ing.

  However, in the above chemical method, the gypsum content in the gypsum-paper joint to be reacted is measured in advance to determine the molar amount of the aqueous caustic soda solution, or the slaked lime content in the slaked lime-paper joint is determined. In addition to determining the molar amount of the acid aqueous solution to be measured in advance, and after dissolving and removing slaked lime, it is actually necessary to separate and wash, not only the operation is complicated and the workability is low, There is a problem that foreign matters such as building waste materials usually contained in the gypsum-paper joint as a raw material cannot be efficiently removed.

Thus, although the gypsum content in the waste gypsum board can be recovered and recycled, an effective recycling method is still provided for the residue containing a large amount of gypsum board paper after separation of the gypsum content. The fact is not.
JP 2006-22460 A

  The present invention has been made in view of the prior art, and from a residue containing a large amount of gypsum board base paper after separating recovered gypsum from waste gypsum board, which has been impossible to recycle, An object of the present invention is to provide a method for efficiently removing waste building materials and easily producing used paper pulp, and a used paper pulp produced from the method, for example, particularly suitable for the production of exterior liners and cores.

  The present invention is at least a waste paper raw material mainly composed of gypsum board waste paper in a disaggregation process, and a waste paper pulp raw material that has undergone the disaggregation process is subjected to a selective process in a selective process mainly composed of a cleaner, The present invention relates to a method for producing waste paper pulp, characterized by subjecting a finely selected product that has undergone a fine selection process to a dehydration concentration process in a dehydration concentration process.

  Furthermore, this invention relates to the used paper pulp obtained with the said manufacturing method.

  In the present invention, a residue containing a large amount of gypsum board base paper with gypsum adhering to the surface after separating the collected gypsum from waste gypsum board is referred to as “gypsum board waste paper”.

  According to the production method of the present invention, it is possible to efficiently remove gypsum residue and building waste from gypsum board waste paper in waste gypsum board that could not be recycled in the past, while reducing the environmental burden at a low cost. Waste paper pulp can be easily produced. Further, the used paper pulp of the present invention obtained by the production method is particularly suitable for, for example, exterior liner and core papermaking.

In the production method of the present invention, at least the following three steps:
(1) A disaggregation process (2) A selection process (3) A dehydration concentration process is performed. Hereinafter, these steps will be described in order.

(Embodiment 1: Basic flow 1)
In FIG. 1, the schematic flowchart showing the process of the manufacturing method of the used paper pulp which concerns on Embodiment 1 is shown.

(1) Disaggregation process First, in this disaggregation process, a diluting water is suitably added to the waste paper raw material which has a gypsum board waste paper as a main component, and a disaggregation process is performed. The waste gypsum board paper, as described above, is a residue containing a large amount of gypsum board base paper with gypsum adhered to the surface after the waste gypsum board is appropriately crushed and sieved to separate the recovered gypsum.

  The disaggregation equipment (pulper) used for the disaggregation process is not particularly limited, and any structure can be used. For example, there is a tab-type pulper in which raw material and water are put into a tab and disaggregation is performed by a stirring force of a rotor provided on the lower or side surface of the tab, and a tab-type low-concentration pulper (treatment concentration: 3.0 to 5.5). (Mass%), tab type medium concentration pulper (treatment concentration: 5.5 to 13.0 mass%), and tab type high concentration pulper (treatment concentration: 13.0 to 18.0 mass%) can be used. . In addition, a drum-type pulper such as a horizontal drum-type pulper with excellent foreign matter discharge capability for the purpose of disaggregation at a higher concentration can be used, and a disaggregation method that applies a strong mechanical shearing force to the undissolved paper itself. It must be a pulper.

  Either a batch type pulper or a continuous type pulper can be used.

  In the first embodiment, the gypsum board waste paper, which is the main component of the waste paper raw material, may of course be used alone or in combination with other waste paper. It is not appropriate if it is too slow compared to waste paper. In particular, when disintegrating with a batch type pulper, the disaggregation time per batch is determined by the disaggregation speed of the waste paper, but if the waste paper to be mixed is indispensable waste paper, only the amount of time required for disaggregation of this indispensable waste paper, It is considered that disaggregation needs to proceed, during which gypsum fragmentation is promoted. On the other hand, if the disaggregation time is adjusted to the waste paper of gypsum board in order to suppress the fragmentation of gypsum, the waste disaggregated waste paper is sorted and discharged without being dissolved, resulting in a decrease in yield and resource saving. It becomes difficult to be done. Therefore, as waste paper mixed with gypsum board waste paper, for example, magazine waste paper, office waste paper, toilet waste paper, high-quality waste paper, medium-quality waste paper, repatriated waste paper, newspaper waste paper, flyer waste paper, and the like, which are easily disaggregated, are preferable. In addition, cardboard waste paper, kraft waste paper, paper tubes, etc. do not meet the above conditions and are not preferable as waste paper to be mixed.

  The disaggregation concentration in the disaggregation process is a condition for suppressing the shearing force applied to the used paper raw material in the pulper. When the disaggregation concentration is too low, mechanical shearing force due to the disaggregation blade and the stirring blade provided in the pulper tends to become prominent rather than disaggregation due to friction between pulp raw materials during disaggregation. Since the gypsum board waste paper contains a large amount of solid gypsum, the gypsum content becomes finer when such mechanical shearing force increases. The refined gypsum content is likely to be difficult to separate in subsequent specific gravity difference separation. Therefore, the disaggregation concentration is preferably 3% by mass or more, and more preferably 5.5% by mass or more. On the other hand, if the disaggregation concentration is too high, the friction between fibers is too strong, so that the dispersion of gypsum proceeds and the fragmentation may proceed, so the disaggregation concentration is 18.0% by mass. The following is preferable.

  The disaggregation pH in the disaggregation step is the pH of the disaggregated water (diluted water) that is introduced into the pulper together with the waste paper raw material mainly composed of gypsum board waste paper.

  Here, when producing a gypsum board, 21% by weight of gypsum is included for crystallization of gypsum. As a result, gypsum crystallizes, but in the manufacturing process of gypsum board, acidic water having a pH of 7 or less is added to the calcined gypsum and crystallized. This is because the gypsum crystallizes in a needle shape in the acidic region, and when adhering to the base paper of the gypsum board, the needle crystallized gypsum is entangled with the paper fiber to obtain high adhesion, and the structure of the gypsum board is more This is because it becomes stronger.

When gypsum is disaggregated in an alkaline region such as pH 10 to 11, scaling may occur inside the pipe to be fed after disaggregation. The cause of this scaling is not clear, but is considered to be because, for example, dihydrate gypsum (CaSO ₄ .2H ₂ O) was once melted by alkaline water and then recrystallized.

From the above, since it is considered that gypsum is a stable substance in the acidic region, the disaggregation pH is preferably 7.0 or less, more preferably 6.8 or less. On the other hand, if the disaggregation pH is too low, that is, it is in a too strongly acidic region, it is necessary to add a large amount of strongly acidic chemicals such as sulfuric acid as pH adjusting chemicals, and carbon dioxide originally mixed in the system. The disaggregation pH is preferably 6.0 or more because calcium (CaCO ₃ ) may be melted to cause a calcium sulfate scale.

  The disaggregation time in the disaggregation step is a condition for suppressing the shearing force applied to the used paper raw material in the pulper, similarly to the disaggregation concentration. When the disaggregation time is too long, the agitation / disaggregation force promotes the fragmentation of gypsum, and the gypsum residue is refined. Since dihydric gypsum has a specific gravity of about 2.3, it can be removed by a cleaner in the next selection process. However, if the refinement proceeds excessively, the removal efficiency by the weight cleaner decreases. Further, it is known from the tests conducted by the inventors of the present invention that the disintegration of the gypsum board base paper itself is completed in about 15 to 20 minutes, and about 90% by mass or more is pulped. However, it is not effective in the present invention to set the length too long because it may further promote the fragmentation of the gypsum due to the stirring / disaggregation force.

  From the above, the disaggregation time is preferably 30 minutes or less, and more preferably 25 minutes or less. On the other hand, if the disaggregation time is too short, the disaggregation of the waste paper raw material mainly composed of gypsum board waste paper may be insufficient. Therefore, the disaggregation time is preferably 15 minutes or more.

  In addition, when using the pulper continuously as a pulper, the disaggregation time should be simply calculated from the input frequency of the used paper raw material to the pulper and the extraction speed of the obtained waste paper pulp raw material from the pulper. Is preferred.

  Moreover, there is no limitation in particular in the disaggregation temperature in a disaggregation process, For example, what is necessary is just normal temperature. Furthermore, the input speed of the used paper raw material to the pulper may be set in consideration of the disaggregation time in accordance with the extraction speed of the used paper pulp raw material from the pulper, and may be appropriately adjusted in consideration of the equipment conditions.

  Thus, the waste paper pulp raw material obtained through the disaggregation process is extracted from the pulper and used in the subsequent selection process. In order to prevent coarse particles from being sent to the selection process, an extraction plate is provided at the pulper outlet. Is preferably provided.

  Gypsum board waste paper is often generated from construction and demolition sites, and therefore contains a large amount of foreign matter such as aluminum stays and demolition wood. For this reason, if the waste paper pulp raw material is extracted from the pulper and directly sent to the fine selection process, the pulper extraction pump may be clogged or the pipe may be clogged, or the cleaner may be clogged in the fine selection process. However, when an extraction plate is provided at the outlet of the pulper and the waste paper pulp raw material is passed through the extraction plate, coarse foreign matters such as aluminum stays and demolished wood, undissolved waste paper, gypsum content with a remarkably large particle size, etc. It can be easily prevented from being sent to the next selection process.

  Here, it is necessary to prevent the passage of coarse foreign matters and the like as described above, but the gypsum content in the waste paper pulp raw material, as described above, is promoted by fragmentation and refinement proceeds, so that the selection process in the selection process That is, removal in the selection process becomes difficult. From these things, it is preferable that the said extraction plate is a round hole shape or square shape which has a major axis of 4.0-18.0 mm, for example, and also 8.0-11.0 mm.

(2) Refinement process Next, in this refinement process, the waste paper pulp raw material which passed through the said disaggregation process is provided to the refinement process which mainly made the process by a refinement | purification equipment (cleaner). That is, diluting water is appropriately added to the used paper pulp raw material to remove the gypsum content (shown as “gypsum slag reject” in FIG. 1) from the used paper pulp raw material.

  When a screen having a diameter of 4 mm or less is used at the beginning of the selection process, for example, clogging usually occurs remarkably and the gypsum content cannot be removed. In this embodiment, the gypsum content is sufficient mainly with a cleaner. To remove.

  As the cleaner, it is preferable to use a cleaner capable of separating foreign substances by a difference in specific gravity. For example, a high concentration cleaner (processing concentration: 3.0 to 5.0 mass%), a medium concentration cleaner (processing concentration: 1. 0 to 3.0% by mass) can be used, and these can be appropriately combined to separate the gypsum content by the difference in specific gravity. However, since the specific gravity of gypsum is 2.3 and it is lighter than ordinary heavy foreign matter (for example, 7.8 for iron, 8.5 for copper, and 2.7 for aluminum), the input pressure, the output pressure, and the injected water pressure By adjusting the concentration and the like in a well-balanced manner, it is possible to separate the gypsum component having a certain size or more from the waste paper pulp raw material.

  Note that, for example, a finely crushed gypsum content may be slightly contained in a selected product obtained by performing a selective treatment with a high-concentration cleaner and removing the gypsum content. In order to further improve the quality of the selected products and further reduce the ash content of waste paper pulp, the waste paper pulp raw material is mainly selected by a high-concentration cleaner or medium-concentration cleaner, and combined with multiple stages of low-concentration cleaners. It is preferable to perform a selective process.

  Further, the processing time in the selection process is not particularly limited as long as the selection process is sufficiently performed, and it is preferable to appropriately adjust, for example, considering workability and the like.

  Further, as described above, since the specific gravity of gypsum is 2.3, it can be easily separated using a difference in specific gravity against ordinary heavy foreign substances such as iron, copper, and aluminum. If the specific gravity difference with gypsum, such as wallpaper containing resin, is very small and contains foreign materials that are difficult to clean with a cleaner, install screen equipment such as a hole screen or slit screen with a high-concentration cleaner or It is preferable that it is provided after the concentration cleaner and further processed in a screen process. Dilution water is appropriately added to the screen facility together with the selected product obtained by the selection process in the selection process.

  After the selection process in the selection equipment (high-concentration cleaner or medium-concentration cleaner), for example, a screen equipment such as a hole screen having a caliber of 1.2 to 2.0 mm, further 1.7 to 2.0 mm and a round hole shape ( In FIG. 1, it is treated at a treatment concentration of 3% by mass or less at “screen equipment I”), and undissolved raw materials such as rough undissolved waste paper (indicated as “undissolved raw material reject” in FIG. 1). It is preferable to remove the lightweight foreign matter (indicated as “lightweight foreign matter reject” in FIG. 1) that has not been removed by the cleaner.

  Further, after the processing by the screen equipment I such as the hole screen, for example, a screen equipment such as a slit screen having a slit width of 0.25 to 0.40 mm, more preferably 0.25 to 0.30 mm (in FIG. In this case, the treatment is performed at a treatment concentration of 2% by mass or less to remove minute gypsum content and undissolved content (shown as “rejection of minute gypsum content” in FIG. 1) having a size larger than the slit width. It is preferable to do.

(3) Dehydration-concentration process Next, in this dehydration-concentration process, the finely selected product that has undergone the above-described selection process is subjected to a dehydration-concentration process.

  There is no particular limitation on the dehydration and concentration equipment used for the dehydration and concentration treatment. For example, a facility capable of dehydrating and concentrating a finely selected product having a concentration of about 0.1 to 1% by mass to a concentration of about 5 to 18% by mass. If it is. By such dehydration concentration treatment, finer gypsum that may be mixed in the selected product can be sufficiently removed.

  The treatment time in the dehydration and concentration step is not particularly limited as long as the dehydration and concentration treatment is sufficiently performed. For example, it is preferable to appropriately adjust in consideration of workability and the like.

  Further, the squeezed water discharged from the dehydration and concentration equipment can be reused as dilution water added to the used paper raw material in the disaggregation process or diluted water added to the used paper pulp raw material in the selective process.

  Thus, the desired waste paper pulp of the present invention can be obtained through the dehydration concentration step. The waste paper pulp obtained by the production method according to Embodiment 1 preferably has the following characteristics (physical properties), for example.

  The ash content of the used paper pulp obtained by the production method according to Embodiment 1 is measured according to the method described in JIS P 8251 “Paper, paperboard and pulp-ash content test method—525 ° C. combustion method”. Therefore, it is preferably 10% or less, more preferably 5 to 10%. The ash content of the waste paper pulp of the present invention is small compared to the ash content of, for example, corrugated waste paper pulp made mainly from corrugated waste paper and magazine waste paper pulp made mainly from magazine waste paper. Particularly suitable for medium core papermaking. In addition, the waste paper pulp has an advantage that the paper strength is easily maintained and scaling within the papermaking system is sufficiently prevented.

  Moreover, when the used paper pulp obtained by the manufacturing method according to Embodiment 1 is disaggregated, the pulp slurry preferably has a pH of 6.0 to 7.1. Since the waste paper pulp of the present invention has a pH near neutral as described above, it is particularly suitable for making a liner for performing weakly acidic to neutral papermaking, for example.

  Furthermore, the gypsum board waste paper used as the main component of the waste paper raw material in the manufacturing method according to Embodiment 1 is a paper whose base paper (gypsum board base paper) is mainly made of mechanical pulp, corrugated waste paper pulp, magazine waste paper pulp, etc. Therefore, the used paper pulp of the present invention obtained by the production method has mechanical strength suitable for, for example, an exterior liner and a core raw material pulp.

Table 1 below shows more preferable properties (physical properties) of waste paper pulp (shown as “gypsum board waste paper pulp” in Table 1) obtained by the production method according to Embodiment 1, and conventional corrugated waste paper pulp and magazine waste paper. The characteristics (physical properties) of the pulp are summarized.

(Embodiment 2: Basic flow 2)
FIG. 2 shows a schematic flow chart showing the steps of the method for producing waste paper pulp according to the second embodiment.

  In the manufacturing method according to the second embodiment, (1) the disaggregation step, (2) the fine selection step, and (3) the dehydration concentration step are all the same as the steps in the manufacturing method according to the first embodiment. Therefore, only the steps different from those of the first embodiment will be described here.

  In the manufacturing method according to Embodiment 1, before the waste paper pulp raw material obtained through the disaggregation process is extracted from the pulper and subjected to the selection process in the next selection process, coarse foreign matter is prevented from being sent to the selection process. Therefore, it is preferable to perform the treatment by providing an extraction plate at the pulper outlet. However, in the second embodiment, instead of providing the extraction plate, immediately after extracting the waste paper pulp raw material from the pulper, another screening facility is used. Perform the screening process.

  The screening step is preferably performed when the quality of used gypsum board waste paper, which is the main component of the used waste paper raw material, is poor and contains, for example, coarse foreign materials such as wood, metal, and plastic.

  Although there is no particular limitation on the screening equipment, the passage of coarse foreign matters as described above must be prevented. Therefore, it becomes difficult to perform the selection process in the selection process, that is, the removal in the selection process. For these reasons, as a screening facility, for example, a round-hole or square-shaped screen plate having a major axis of 4.0 to 18.0 mm, more preferably 8.0 to 11.0 mm is preferable.

  Thus, the used paper pulp obtained by the manufacturing method according to the second embodiment preferably has the same characteristics (physical properties) as the used paper pulp obtained by the manufacturing method according to the first embodiment, for example.

(Embodiment 3: Basic flow 3)
In FIG. 3, the schematic flowchart showing the process of the manufacturing method of the used paper pulp which concerns on Embodiment 3 is shown.

  In the manufacturing method according to the third embodiment, (1) the disaggregation step, (2) the fine selection step, and (3) the dehydration concentration step, and the screening step immediately after the disaggregation step are basically all of the second embodiment. Each of the steps is the same as the process in the manufacturing method. Therefore, only the steps different from those of the second embodiment will be described here.

  In the production method according to the second embodiment, the quality of the used gypsum board used as the main component of the used paper raw material is poor, and, for example, when a coarse foreign material such as wood, metal, or plastic is included, the disaggregation process in the disaggregation process. In the third embodiment, the pulper used in the disaggregation process is further prevented immediately after extracting the waste paper pulp raw material from the pulper, by performing a screening process using a screening facility to prevent these coarse particles from being sent to the selective process. A metal trap is provided to remove the metallic coarse particles at an early stage.

  By providing the metal trap in the pulper, the metallic coarse particles can be removed at an early stage in the disaggregation process, so that the pulper can be prevented from being deteriorated and the pulper can be prevented from being clogged.

  The disaggregation treatment is performed while removing the metallic coarse particles by the metal trap, and the obtained waste paper pulp raw material is directly screened. In this Embodiment 3, the metallic coarse particles are already removed. Wood-based and plastic-based coarse foreign matter is removed.

  In addition, in the manufacturing method according to the third embodiment, a screen facility such as a hall screen (“screen facility I” in FIG. 3) that is preferably performed after the selective process in the selective facility (high concentration cleaner or medium concentration cleaner). It is preferable that the process density | concentration by the process by is 3.0 mass% or less.

  Thus, the waste paper pulp obtained by the production method according to the third embodiment preferably has the same characteristics (physical properties) as the waste paper pulp obtained by the production method according to the second embodiment, for example.

(Embodiment 4: Application flow)
In FIG. 4, the schematic flowchart showing the process of the manufacturing method of the used paper pulp which concerns on Embodiment 4 is shown.

  In the manufacturing method according to Embodiment 4, (1) the disaggregation step, (2) the fine selection step, and (3) the dehydration concentration step, and the treatment with the extraction plate provided at the pulper outlet used in the disaggregation step are basically These are the same as the steps in the manufacturing method according to the first embodiment. Therefore, only the steps different from those of the first embodiment will be described here.

  First, in the manufacturing method according to the fourth embodiment, the quality of the gypsum board used paper, which is the main component of the used paper raw material, is poor, for example, when it contains coarse foreign material such as wood, metal or plastic, When the amount of used paper is large, a separate screening facility is provided during the disaggregation process in the disaggregation process, so that these coarse particles are not sent to the extraction plate provided at the pulper outlet. .

  In the screening process according to the fourth embodiment, as screening equipment, equipment capable of separating specific gravity difference of heavy metal-based foreign matter in weight reject by centrifugation or simple sedimentation, wood-based, plastic-based coarse in lightweight reject A combination of equipment capable of removing lightweight foreign substances by screening is used. By the processing in such a screening facility, these coarse and heavy foreign matter can be continuously separated and removed, and the coarse foreign matter can be crushed and the equipment deterioration due to the metallic coarse foreign matter can be prevented.

  In the fourth embodiment, the waste paper raw material that has undergone the screening process is charged again into the pulper and subjected to a disaggregation process. As described above, in the fourth embodiment, the waste paper raw material is circulated between the pulper and the screening facility (the waste paper raw material is indicated as “circulation raw material” in FIG. 4).

  Furthermore, in the manufacturing method according to the fourth embodiment, a fine gypsum fraction (“Reject A” in FIG. 4) having a size equal to or larger than the slit width is obtained by processing with a screen equipment such as a slit screen (“Screen Equipment II” in FIG. 4). The fine gypsum content is carefully selected with a low-concentration cleaner (treatment concentration: 0.6% by mass or less), and the fine gypsum content larger than the slit width is removed out of the system. (The fine gypsum content removed outside the system is indicated as “Reject B” in FIG. 4), and the resulting refined product (indicated as “Recovered raw material” in FIG. 4) is transferred to the next dehydration and concentration facility. And send. As a result of the combination of the screen facility and the low-concentration cleaner in the fourth embodiment, the ash content in the waste paper pulp finally obtained can be further reduced.

  In addition, diluting water is appropriately added to the fine gypsum content obtained by the processing in the screen equipment II such as the slit screen, and this is then carefully selected by a low-concentration cleaner. The squeezed water discharged from the dehydration and concentration equipment can be used.

  Further, in the processing in the screen equipment II, for example, a selected product having a size less than the slit width of the slit screen is not sent to the low-concentration cleaner, but is directly sent to the next dehydration and concentration equipment, It is used for dehydration concentration treatment.

  Thus, the waste paper pulp obtained by the production method according to the fourth embodiment preferably has the same properties (physical properties) as the waste paper pulp obtained by the production method according to the first embodiment, for example. The ash is even less.

  As described above, according to the manufacturing method of the present invention, gypsum residue and building waste materials are efficiently removed from the gypsum board waste paper in the waste gypsum board that could not be recycled in the past, while reducing the environmental burden. Waste paper pulp can be easily produced at low cost. Further, the used paper pulp of the present invention obtained by the production method has little ash, suitably has good mechanical strength, and the pulp slurry has a pH near neutral. Especially suitable for papermaking.

  Next, although the used paper pulp and its manufacturing method of this invention are demonstrated in detail based on the following Examples, this invention is not limited only to these Examples.

Examples 1-1 to 18
Waste paper pulp was produced according to the schematic flow diagram of FIG.

(1) Disaggregation process 500 kg (air-dried) gypsum board waste paper is put into a tab-type low-concentration pulper (treatment concentration: 5.0% by mass) or a tab-type high-concentration pulper (treatment concentration: 15.0% by mass). Diluted water was added and disaggregation was performed at room temperature under the conditions shown in Table 2 to obtain used paper pulp raw materials.

  The obtained waste paper pulp raw material was passed through an extraction plate (major diameter: 10.0 mm, round hole shape) provided at the pulper outlet and extracted from the pulper. Table 2 shows the pulp yield of the used paper pulp raw material.

(2) Careful selection process Diluted water is added to the waste paper pulp raw material extracted from the pulper, treated with a high-concentration cleaner (treatment concentration: 4.0% by mass), and then treated with a hole screen (caliber: 2.0 mm, round hole shape). Then, undissolved raw materials and lightweight foreign matters were removed, and then the fine gypsum content was removed by treatment with a slit screen (slit width: 0.25 mm). Thereafter, a low-concentration cleaner (treatment concentration: 1.5% by mass or less) was further combined and subjected to a fine selection process, and the gypsum content was removed from the system to obtain a selected product. The concentration of the selected product is shown in Table 2.

(3) Dehydration and concentration step The obtained finely selected product was dehydrated and concentrated with a dehydration concentration facility until the concentration shown in Table 2 (shown as the concentration of dehydrated concentrate in Table 2) was obtained to obtain waste paper pulp.

  About the obtained waste paper pulp, each characteristic (physical property) was measured with the following method. These results are shown in Table 3.

(A) Ash content Measured according to the method described in JIS P 8251 “Paper, paperboard and pulp-ash content test method—525 ° C. combustion method”.

(B) pH of pulp slurry
About 250 mL of the sample slurry was filtered with a filter paper (C5, manufactured by ADVANTEC), and the pH of the filtrate was measured with a glass electrode type hydrogen ion concentration meter (type: D-13, manufactured by Horiba, Ltd.).

(C) Canadian Standard Freeness (CSF)
In accordance with the method described in JIS P 8251 “Pulp Freeness Test Method”, measurement was performed using a Canadian Standard Freeness Tester (model number: Canadian Standard Freeness Meter, manufactured by Toyo Seiki Seisakusho Co., Ltd.).

(D) Specific burst strength A pulp sheet prepared in accordance with the method described in JIS P 8222 “Method for adjusting hand-made paper for test” is used as a test for JIS P 8223 “Test hand-made paper—physical properties”. Measured according to the method described in JIS P 8112 “Testing method for burst strength of paper and paperboard using a Murren low-pressure burst tester” prescribed in “Method”.

(E) Specific tear strength A pulp sheet prepared in accordance with the method described in JIS P 8222 “Method for adjusting hand-made paper for test” was used as a test for JIS P 8223 “Test hand-made paper—physical properties”. Measured according to the method described in JIS P 8116 “Paper-Tear Strength Test Method—Elmendorf Tear Tester Method” defined in “Method”.

(F) Specific ring strength A pulp sheet prepared in accordance with the method described in JIS P 8222 “Method for preparing hand-made paper for test” was used as a test for JIS P 8223 “Test hand-made paper—physical properties”. Measured according to the method described in JIS P 8126 “Paper and paperboard—Compression strength test method—Ring crush method” prescribed in “Method”.

  From the results shown in Table 3, the waste paper pulp obtained by the production method according to Embodiment 1 of the present invention has a relatively low ash content, and the pH of the pulp slurry is approximately neutral, and is a good machine. It can be seen that it has a sufficient strength.

Example 2
Waste paper pulp was produced according to the schematic flow diagram of FIG.

(1) Disaggregation process 500 kg (air-dried) of gypsum board waste paper containing a large amount of coarse foreign matter is added to a tab-type high-concentration pulper (treatment concentration: 15.0% by mass). The disaggregation process was performed on the conditions shown in FIG. Table 2 shows the pulp yield of the used paper pulp raw material.

  Next, the waste paper pulp raw material extracted from the pulper was passed through a screen plate (major axis: 10.0 mm, round hole shape), and wood-based, metal-based and plastic-based coarse foreign matters were removed out of the system.

(2) Refinement process Diluted water is added to the waste paper pulp material from which coarse foreign matter has been removed with a screen plate, and after treatment with a high-concentration cleaner (treatment concentration: 4.0% by mass), a hole screen (caliber: 2.0 mm, round) Undissolved raw materials and light-weight foreign substances were removed by treatment with a hole shape, and then fine gypsum was removed by treatment with a slit screen (slit width: 0.25 mm). Thereafter, a low-concentration cleaner (treatment concentration: 1.5% by mass or less) was further combined and subjected to a fine selection process, and the gypsum content was removed from the system to obtain a selected product. The concentration of the selected product is shown in Table 2.

(3) Dehydration and concentration step The obtained finely selected product was dehydrated and concentrated with a dehydration concentration facility until the concentration shown in Table 2 (shown as the concentration of dehydrated concentrate in Table 2) was obtained to obtain waste paper pulp.

  About the obtained used paper pulp, each characteristic (physical property) was measured like Example 1-1-18. These results are shown in Table 3.

  From the results shown in Table 3, the waste paper pulp obtained by the production method according to Embodiment 2 of the present invention has an ash content as low as 10% or less, the pH of the pulp slurry is near neutral, and is excellent. It can be seen that it has mechanical strength.

Example 3
Waste paper pulp was produced according to the schematic flow diagram of FIG.

(1) Disaggregation process 500 kg (air-dried) of gypsum board waste paper containing a large amount of coarse foreign matter is added to a tab-type high-concentration pulper (treatment concentration: 15.0% by mass). The disaggregation process was performed on the conditions shown in Fig. 1 and the pulp was extracted from the pulper to obtain a used paper pulp raw material. Table 2 shows the pulp yield of the used paper pulp raw material.

  The pulper is provided with a metal trap, and during this disaggregation process, metallic coarse particles in the system were removed out of the system by the metal trap.

  Next, the waste paper pulp raw material extracted from the pulper was passed through a screen plate (major axis: 10.0 mm, round hole shape) to remove wood-based and plastic-based coarse foreign substances out of the system.

(2) Selection process Diluted water is added to waste paper pulp raw material from which coarse foreign matters have been removed with a metal trap and a screen plate, and after treatment with a high-concentration cleaner (treatment concentration: 4.0% by mass), a hole screen (caliber: 2. The undissolved raw material and light-weight foreign substances were removed by treatment with 0 mm, round hole shape), and then the fine gypsum content was removed by treatment with a slit screen (slit width: 0.25 mm). Thereafter, a low-concentration cleaner (treatment concentration: 1.5% by mass or less) was further combined and subjected to a fine selection process, and the gypsum content was removed from the system to obtain a selected product. The concentration of the selected product is shown in Table 2.

(3) Dehydration and concentration step The obtained finely selected product was dehydrated and concentrated with a dehydration concentration facility until the concentration shown in Table 2 (shown as the concentration of dehydrated concentrate in Table 2) was obtained to obtain waste paper pulp.

  About the obtained used paper pulp, each characteristic (physical property) was measured like Example 1-1-18. These results are shown in Table 3.

  From the results shown in Table 3, the waste paper pulp obtained by the production method according to Embodiment 3 of the present invention has a low ash content of 10% or less, and the pH of the pulp slurry is near neutral and excellent. It can be seen that it has mechanical strength.

Example 4
Waste paper pulp was produced according to the schematic flow diagram of FIG.

(1) Disaggregation process 500 kg (air-dried) of gypsum board waste paper containing a large amount of coarse foreign matter is added to a tab-type high-concentration pulper (treatment concentration: 15.0% by mass), and diluted water is added thereto. Disaggregation processing was performed under the conditions shown.

  In addition, the screening equipment provided separately at the same time as the disaggregation process (a combination of equipment capable of separating the specific gravity difference of metal-based coarse and heavy foreign matter by centrifugation and equipment capable of removing wood-based and plastic-based coarse and lightweight foreign matter by screening) ) To separate and remove metal-based coarse and heavy foreign materials and wood-based and plastic-based coarse and lightweight foreign materials continuously outside the system.

  The used gypsum board waste paper screened in the screening equipment was again put into the pulper and treated by circulating the gypsum board waste paper between the pulper and the screening equipment to obtain a used paper pulp raw material.

  The obtained waste paper pulp raw material was passed through an extraction plate (major diameter: 10.0 mm, round hole shape) provided at the pulper outlet and extracted from the pulper. Table 2 shows the pulp yield of the used paper pulp raw material.

(2) Refinement process Diluted water is added to the waste paper pulp material extracted from the pulper, and it is carefully selected with a high-concentration cleaner (treatment concentration: 4.0% by mass) to remove the gypsum content from the system and remove the selected product. Obtained.

  Next, diluting water is added to the selected product obtained, and undissolved raw materials and lightweight foreign substances are removed by treatment with a hole screen (caliber: 2.0 mm, round hole shape). Further, a slit screen (slit width: 0.00 mm) is obtained. The fine gypsum having a size larger than the slit width was removed by the treatment of 25 mm) to obtain a treated product (fine gypsum). Next, this processed product is carefully selected with a low-concentration cleaner (processing concentration: 0.5% by mass), and fine gypsum larger than the slit width is removed from the system to obtain a selected product (recovered material). It was. Table 2 shows the concentrations of the finely selected product and the recovered raw material that have a size less than the slit width of the slit screen and were not sent to the low concentration cleaner.

(3) Dehydration and concentration step The finely selected product and the recovered raw material that have a size less than the slit width of the slit screen and were not sent to the low-concentration cleaner are shown in Table 2 (in Table 2, the concentration of the dehydrated concentrate). It was dehydrated and concentrated with a dehydration and concentration equipment until it was expressed) to obtain waste paper pulp.

  About the obtained used paper pulp, each characteristic (physical property) was measured like Example 1-1-18. Table 3 shows these results.

  From the results shown in Table 3, the waste paper pulp obtained by the production method according to Embodiment 4 of the present invention has an extremely low ash content of 5%, and the pH of the pulp slurry is near neutral and excellent. It can be seen that it has mechanical strength. Moreover, in this manufacturing method, since the circulation process which combined the slit screen and the low concentration cleaner is performed between a selection process and a dehydration concentration process, it turns out that the ash content of the obtained used paper pulp is still less.

  According to the production method of the present invention, it is possible to recycle waste paper from gypsum board that could not be recycled conventionally. Further, the used paper pulp of the present invention can be particularly suitably used for, for example, exterior liners and core papermaking.

Schematic flowchart showing the steps of the method for producing waste paper pulp according to Embodiment 1 Schematic flow chart showing the steps of the method for producing waste paper pulp according to Embodiment 2 Schematic flowchart showing the steps of the method for producing waste paper pulp according to Embodiment 3 Schematic flow chart showing the steps of the method for producing waste paper pulp according to Embodiment 4

Claims (5)

  At least, the waste paper raw material mainly composed of gypsum board waste paper is disaggregated in the disaggregation process, and the waste paper pulp raw material that has undergone the disaggregation process is subjected to a selective process in a selective process mainly consisting of treatment with a cleaner, and then passed through the selective process. A method for producing waste paper pulp, comprising subjecting a selected product to a dehydration concentration process in a dehydration concentration step.   The manufacturing method of Claim 1 which performs the disaggregation process of a used paper raw material on conditions with a disaggregation density | concentration of 3 mass% or more and a disaggregation time of 30 minutes or less in a disaggregation process.   The production according to claim 1 or 2, wherein, in the selection process, the waste paper pulp raw material that has undergone the disaggregation process is mainly subjected to a selection process using a high-concentration cleaner or a medium-concentration cleaner, and further combined with a plurality of low-concentration cleaners. Method.   Waste paper pulp obtained by the production method according to claim 1.   The used paper pulp of Claim 4 whose ash content measured based on the method of JISP8251 is 10% or less.

Images