How to regenerate pulp from gypsum board

Abstract

To provide a pulp regeneration method for obtaining a regenerated pulp from a gypsum board by using most of a paper-making plant such as a waste newspaper.SOLUTION: Disclosed is a pulp regeneration method successively conducting a) a release paper liquefaction step, wherein the release paper liquefaction step employs a release paper released from a gypsum board as a raw material and the release paper is fed to a stirring device, followed by feeding water to dissolve the release paper, b) a loosening step of sending a solution of the liquefied release paper to a 3-shaft kneading device, followed by loosening while warming to an ordinary temperature or higher, c) a foreign matter removal step of sending the solution to a screening device, followed by removing a foreign matter from the solution, d) a gypsum removal step of sending the foreign matter-removed solution to a foaming device, followed by removing a gypsum component impregnated from a fiber, e) a fiber recovery step of recovering the fiber only by sending the gypsum component-removed solution to a concentration cleaning device, followed by washing gypsum attached to a surface of the fiber, and f) a sheet formation step of sending the recovered fiber to a papermaking net device, followed by forming to sheet-like shape.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for regenerating pulp from a material (hereinafter referred to as release paper) obtained by peeling paperboard contained in waste gypsum board from gypsum. [Background technology]

[0002] Generally, gypsum boards are made by pasting paperboard made of recycled paper or pulp on both sides of the gypsum board to reinforce it. For this reason, various attempts have been made to recycle the release paper, which is the paperboard peeled off from the waste gypsum board. weight% Because the gypsum components remain on the front and back of the paper and are fixed between the fibers, it is extremely difficult to extract only the paper components as pulp. For this reason, most of the paper is currently disposed of by incineration or burial, which is costly.

[0003] However, a proposal to remove gypsum from waste gypsum board and use it as a granular excrement treatment material is described in Patent Document 1. Paragraph number

[0006] of this specification describes recovering paperboard with a small amount of gypsum attached, and paragraph number

[0047] describes separating gypsum from waste gypsum board and recovering paperboard.

[0004] Since this paperboard is not completely free of gypsum, even if recycled pulp is obtained using the same paper manufacturing plant as used for conventional newspapers, the gypsum components easily wear down and damage the parts inside the equipment. The process for obtaining recycled pulp from newspapers, etc., includes a) a waste paper liquefaction process in which newspapers, etc. are put into a pulper (mixing device) and water is poured in to liquefy the waste paper, b) a kneading process using a kneader (mixing device), c) a foreign matter removal process in which foreign matter such as metal and vinyl pieces are removed using a screen (sorting device), d) an ink removal process in which ink, etc. is floated and removed using a floatator (foaming device), e) a fiber recovery process in which only fibers are recovered using a concentration and washing device, and f) a sheet formation process in which the above processes are formed into sheets using a wire (papermaking net device), as shown in Figure 2, and the above processes are carried out sequentially at least in the order described above. The loosening time in the loosening process was about 5 seconds, which was sufficient for general waste newspapers. Conventional pulpers used a single shaft, and when obtaining recycled pulp from release paper, the current situation was that insufficient dissociation occurred even when loosening was performed by stirring alone. Furthermore, there was currently no method for efficiently and inexpensively regenerating pulp, and there was a demand for the development of a new method for regenerating pulp from gypsum board. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-333773 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have made this invention as a result of extensive research into whether pulp recycling can be carried out efficiently and inexpensively by improving the configuration and performance of some of the equipment in paper manufacturing plants for used newspaper, etc. That is, the object of the present invention is to provide a pulp recycling method that utilizes most of the paper manufacturing plants for used newspaper, etc. to obtain recycled pulp from gypsum boards. [Means for solving the problem]

[0007] The present invention has been made to meet the above demands, and is a method for obtaining recycled pulp by utilizing the majority of paper manufacturing plants for newspaper waste paper, etc. That is, the process includes a) a liquefaction process in which the release paper peeled from the gypsum board is put into a mixing device and water is poured in to dissolve the release paper, and b) a solution of the liquefied release paper is sent to a three-axis kneading device and the temperature of the solution is adjusted. was maintained in the range of 40℃~60℃. c) a kneading process in which the mixture is kneaded in a state where it is loosened; c) a foreign matter removing process in which the solution is sent to a sorting device and foreign matter in the solution is removed; d) a gypsum removing process in which the solution from which the foreign matter has been removed is sent to a foaming device and the gypsum component impregnated in the fibers is removed; e) a fiber recovering process in which the solution from which the gypsum component has been removed is sent to a concentrated washing device and the gypsum attached to the surface of the fibers is washed and only the fibers are recovered; and f) a sheet forming process in which the recovered fibers are sent to a papermaking net device and formed into a sheet, and the above processes are carried out sequentially at least in the order described. T, b ) The massage time during the massage process should be between 2 and 5 minutes. Furthermore The fiber length after the kneading step b) is preferably in the range of 0.01 mm to 0.15 mm. 、 In the kneading step (b), a bleaching agent is preferably added, and sodium hypochlorite is preferably used as the bleaching agent, and in the gypsum removing step (d), the cleaning time is preferably set within a range of 10 to 15 minutes.Furthermore, it is preferable to use screw shafts equipped with a group of spiral rotating blades as the three shafts of the kneading device, and to place the tip side of the second screw shaft on the delivery side of the first screw shaft, and to place the tip side of the third screw shaft on the rear end side of the second screw shaft. Effect of the Invention

[0008] As shown in claim 1, a) the release paper peeled off from the gypsum board is put into a mixing device and water is poured in to dissolve the release paper, and b) a solution of the liquefied release paper is sent to a three-axis kneading device and the solution is mixed with the mixture. was maintained in the range of 40℃~60℃.The present invention comprises a kneading process in which the gypsum board is kneaded in a state where it is in a kneading state; a foreign matter removal process in which the solution is sent to a sorting device and foreign matter in the solution is removed; a gypsum removal process in which the solution from which the foreign matter has been removed is sent to a foaming device and the gypsum component impregnated in the fiber is removed; a fiber recovery process in which the solution from which the gypsum component has been removed is sent to a concentrated washing device to wash the gypsum attached to the surface of the fiber and only the fiber is recovered; and a sheet formation process in which the recovered fiber is sent to a papermaking net device and formed into a sheet shape. By carrying out the above processes in sequence at least in the order described above, it becomes possible to regenerate pulp from gypsum board, which was previously impossible. This eliminates the need for incineration and disposal by burying it in the ground. Moreover, waste materials that were previously disposed of can be effectively utilized as resources as recycled pulp. Furthermore, since most of the conventional papermaking plants for used newspaper, etc. can be used, pulp regeneration can be carried out efficiently and inexpensively, and the method for producing recycled pulp is also environmentally friendly.

[0009] Claim 2 As shown in Fig. 2, by setting the kneading time in the kneading process in the range of 2 to 5 minutes, pulp regeneration can be carried out efficiently.

[0010] Claim 3 As shown in Fig. 2, by setting the fiber length after the kneading process to within the range of 0.01 mm to 0.15 mm, pulp regeneration can be carried out efficiently.

[0011] Claim 4 In the kneading process b), by adding a bleaching agent and using sodium hypochlorite as the bleaching agent, the fibers do not turn red as in the past, and a stronger bleaching effect can be expected, increasing the product value. Also, when bleaching boards, the fibers do not turn red as in the past, increasing the product value.

[0012] Claim 5 As described above, by setting the washing time in the gypsum removal step d) within the range of 10 to 15 minutes, the gypsum can be washed sufficiently, and therefore the gypsum can be removed almost completely.

[0013] Claim 6 As shown in FIG. 1, screw shafts equipped with a group of spiral swirling blades are used as the triple shafts of the kneading device, and the tip side of the second screw shaft is disposed on the delivery side of the first screw shaft, and the tip side of the third screw shaft is disposed on the rear end side of the second screw shaft. This lengthens the kneading path and the kneading time, thereby improving the degree of fiber dissociation. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram illustrating an embodiment of the present invention. [Diagram 2] FIG. 1 is a block diagram showing a conventional pulp regeneration method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The process of recycling pulp from gypsum board according to the present invention will be described with reference to FIG. 1. A raw material (release paper) is prepared by crushing paperboard peeled from a gypsum board. This release paper contains 10% gypsum components. weight% It is fixed in the fibers, including the front and back.

[0016] First, a) "liquefaction process of release paper" will be described. First, the release paper from which the paperboard has been crushed is placed in a high-dissociation agitator, and the release paper is dissolved by pouring in water and agitating. At this time, a slush pulper is used as the high-dissociation agitator. As the slush pulper, for example, the Slush Pulper 3000 model manufactured by Kyowa Iron Works Co., Ltd. can be used. Compared to conventional pulpers, the size of the clumps of sheared fiber pieces is about 1 / 100th of that size in this process, compared to the conventional pulpers, which are about 10 mm in size. Incidentally, dissociation is also called fiber defibration, and means breaking down fibers into pieces.

[0017] Next, b) "kneading process" will be explained. The liquefied release paper is sent to a kneading device, where the fibers are kneaded and the gypsum attached to the fibers is separated. Generally, a single-shaft kneading device is used for this process, but in this process, a three-shaft kneading device is used to enable more detailed kneading. An example of a three-shaft kneading device is the New Ta The Izen 70 model can be used. In this case, the three shafts of the kneading device are screw shafts equipped with a group of spiral swirling blades, and the tip of the second screw shaft is placed on the delivery side of the first screw shaft, and the tip of the third screw shaft is placed on the rear end side of the second screw shaft, so that the first screw shaft is connected to the third screw shaft. Compared to the conventional single-shaft kneader, the use of a three-shaft kneader makes the path for kneading the fibers longer, the degree of fiber dissociation increases, and more gypsum and fibers are separated. The fiber length at this time is in the range of 0.01mm to 0.15mm. If the fiber length is 0.15mm or more, there is a risk that it will be rejected by the sorting device used in the subsequent process and treated as waste. In addition, the fiber length cannot be processed to less than 0.01mm. Furthermore, by performing the kneading time for about 2 to 5 minutes, the gypsum adheres to the fibers, so the gypsum will collide with each other. This generates frictional heat, raising the solution temperature in the release paper to around 40°C, making it easier for water to penetrate the fibers and loosen them. At this time, a heater or other device is used to control the temperature so that the solution temperature rises. stomach, The temperature of the solution is in the range of 40°C to 60°C. Maintain If the temperature is below 40°C, the fibers may not be loosened efficiently, and if it is above 60°C, the efficiency of loosening the fibers increases but the cost increases. If the kneading time is below 2 minutes, poor dissociation is likely to occur, and if it is above 5 minutes, the cost increases. In the conventional process, the kneading process was carried out with a solution temperature of 20°C or less. There are also two-shaft kneaders, which are used to separate the pulp from the release paper. R Even if you try to regenerate the paste, the dissociation does not occur completely, and some parts remain as lumps that cannot be loosened.

[0018] In the kneading process of the present invention, sodium hypochlorite is added as a bleaching agent and caustic soda is added as a dissociation promoter. At this time, the solution is heated to about 40°C as described above, so the bleaching agent penetrates easily and the bleaching effect is improved. When used newspapers and other waste paper are bleached with hydrogen peroxide, and when board materials are bleached with this, they are tinged red and their commercial value is reduced. However, when sodium hypochlorite is used, the redness disappears.

[0019] After that, c) "foreign matter removal process" is carried out. This will be explained. First, the loosened fibers are sent to a screening device to remove foreign matter. This screening process involves two processes, a rough screening process and a refinement process. For the rough screening process, for example, IHI's P H A screen type 12 is used, and for the screening process, for example, an FN screen manufactured by Satomi Seisakusho Co., Ltd. can be used. At this time, foreign matter such as gypsum, metal, and vinyl pieces are removed by settling and centrifugal force. After this foreign matter removal process, the gypsum in the fibers is 5 weight% The process of removing foreign matter (c) is essentially the same as the conventional process.

[0020] Furthermore, d) "gypsum removal process" is carried out. This will be explained. When the gypsum adhering to the fibers is removed and sent to the foaming device, The fine gypsum particles adhering to the surface of the foam and the gypsum components in the liquid are caused to adhere to the surface of the foam and float to the liquid surface for removal. As a result, the gypsum components are almost completely removed from the fibers. As the foaming device, for example, a floater manufactured by San-ei Regulator Co., Ltd. can be used. The gypsum is washed for 10 to 15 minutes. If the washing time is less than 10 minutes, there is a risk that the gypsum will not be removed and will remain, and if it is more than 15 minutes, the cost will be high.

[0021] Then, the gypsum adhering to the surface of the fibers is washed off in a concentration washing device, and only the fibers are recovered without any gypsum components attached thereto. This is followed by a "fiber recovery process" (e), in which the recovered fibers are sent to a papermaking machine and formed into a sheet. This sheet is then dried to obtain recycled pulp. Examples of the concentration washing device include the gypsum-free pulp made by Daizen Co., Ltd. Ta An Izen type concentrated washing device can be used. As the papermaking mesh device, for example, a wire device manufactured by Kobayashi Seisakusho Co., Ltd. can be used. The washing time in the above-mentioned e) "fiber recovery process" is 10 to 15 minutes. If the washing time is less than 10 minutes, there is a risk that the gypsum will not be removed and will remain, and if it is more than 15 minutes, the cost will be high. The e) "fiber recovery process" and f) "sheet formation process" are the same as the conventional processes.

[0022] The present invention utilizes most of the conventional paper manufacturing plants, and by sequentially carrying out the above steps, pulp recycled paper can be efficiently obtained from the sheet-shaped release paper peeled off from the gypsum board, making it possible to effectively recover resources and providing a method for inexpensively producing pulp recycled paper.

Claims

1. a) a release paper liquefaction process in which the release paper peeled off from the gypsum board is placed in a mixing device and water is poured in to dissolve the release paper; b) a kneading step in which a liquefied release paper solution is sent to a three-axis kneading device and kneaded while the temperature of the solution is maintained in the range of 40°C to 60°C; c) a foreign matter removal step of sending the solution to a sorting device and removing foreign matter in the solution; d) A gypsum removal step in which the solution from which the foreign matter has been removed is sent to a foaming device to remove the gypsum component impregnated in the fibers; e) A fiber recovery process in which the solution from which the gypsum components have been removed is sent to a concentrated washing device, the gypsum adhering to the surface of the fibers is washed, and only the fibers are recovered; f) a sheet forming step of feeding the recovered fibers to a papermaking machine and forming the fibers into a sheet; A method for regenerating pulp from gypsum board, comprising the steps of:

2. The method for regenerating pulp from a gypsum board according to claim 1, wherein the kneading time in the kneading step b) is in the range of 2 to 5 minutes.

3. The method for regenerating pulp from gypsum board according to claim 1 or 2, wherein the fiber length after the b) kneading step is in the range of 0.01 mm to 0.15 mm.

4. 4. The method for regenerating pulp from gypsum board according to claim 1, 2 or 3, wherein a bleaching agent is added in the kneading step b), and sodium hypochlorite is used as the bleaching agent.

5. 2. The method for regenerating pulp from a gypsum board according to claim 1, wherein the washing time in the gypsum removal step (d) is in the range of 10 to 15 minutes.

6. 2. The method for regenerating pulp from gypsum board according to claim 1, wherein the three shafts of the kneading device are screw shafts equipped with a group of spiral rotating blades, the tip side of the second screw shaft is disposed on the delivery side of the first screw shaft, and the tip side of the third screw shaft is disposed on the rear end side of the second screw shaft.

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