Method for recycling waste gypsum board, method for manufacturing raw materials for resin processed products using waste gypsum board, method for manufacturing raw materials for cement using waste gypsum board, and type II anhydrous gypsum obtained from waste gypsum board

Abstract

To provide a recycling method for a waste gypsum board that enables efficient production of high-purity and fine gypsum from the waste gypsum board and expands a range of applications for gypsum obtained from the waste gypsum board.SOLUTION: A recycling method for a waste gypsum board executes: a first pulverization separation process (S1) of pulverizing a waste gypsum board containing a gypsum core material and paper attached to the gypsum core material, and separating intermediate gypsum powder obtained by pulverizing the gypsum core material from the paper; a heating process (S2) of heating the intermediate gypsum powder to form Type II anhydrous gypsum, and burning off residues including paper and / or plastic contained in the intermediate gypsum powder; and a second pulverization separation process (S3) of pulverizing the intermediate gypsum powder after the heating process into fine gypsum powder by an air-flow type crusher, and separating residues including sand contained in the intermediate gypsum powder from the fine gypsum powder at a classification part of the air-flow type crusher.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for recycling waste gypsum board, a method for producing a raw material for a resin processed product using waste gypsum board, a method for producing a raw material for cement using waste gypsum board, and type II anhydrous gypsum obtained from waste gypsum board. [Background technology]

[0002] Gypsum board is a very useful building material and is widely used in various buildings. However, the amount of waste gypsum board generated during, for example, the demolition of buildings is enormous and is expected to increase in the future.

[0003] Waste gypsum board is recyclable; specifically, the gypsum and paper extracted from waste gypsum board can be recycled as recyclable resources. Currently, for example, most of the gypsum extracted from waste gypsum board is used to remanufacture gypsum board or as a solidification material for sludge, etc. However, the amount of recycled waste gypsum board is very small compared to the total amount of waste gypsum board generated. In reality, most waste gypsum board is landfilled. In other words, it cannot be said that the improvement and widespread adoption of the recycling environment for waste gypsum board is progressing as desired.

[0004] Currently, waste gypsum board is disposed of in landfills at controlled industrial waste disposal sites. However, there are limitations to the land available for such disposal sites, and in order to reduce environmental impact and health hazards, it is desirable to avoid such operations as much as possible.

[0005] For these reasons, it is desirable to realize an environment in which as much waste gypsum board as possible can be recycled. In response to these circumstances, various technologies for processing waste gypsum board have been proposed, and are disclosed in, for example, Patent Documents 1 to 4. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-36207 [Patent Document 2] Japanese Patent Publication No. 2023-36205 [Patent Document 3] Japanese Patent Publication No. 2022-24689 [Patent Document 4] Patent No. 6088277 Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors believe that the reasons why the improvement and widespread adoption of the recycling environment for waste gypsum boards has not progressed as desired are the following (1) to (4). (1) The main uses of the gypsum extracted from waste gypsum board (remanufacturing gypsum board and as a hardening agent) are currently very limited. In other words, the market is limited, and not many companies are willing to enter the market. (2) The gypsum extracted from waste gypsum boards is generally required to be in the form of gypsum dihydrate and needle-like crystals. In other words, these characteristics and properties limit the uses for reuse and make it difficult to expand the market (uses). (3) The gypsum extracted from the current waste gypsum board still contains some foreign matter, such as sand and plastic, which can cause undesirable effects, for example, on the environment, limiting its uses. (4) Recycling waste gypsum board requires a lot of cost and effort, which acts as a barrier to entry.

[0008] The present inventors have conducted extensive research in light of the above circumstances and have found that by devising the properties of the gypsum extracted from waste gypsum board and the manufacturing process, its uses can be expanded.

[0009] Specifically, the inventors have discovered that by converting the gypsum extracted from waste gypsum board into fine anhydrous gypsum, particularly type II anhydrous gypsum, and properly removing impurities, and by simplifying the process to achieve this, the takt time and manufacturing costs can be reduced, thereby significantly expanding the uses of the gypsum extracted from waste gypsum board.

[0010] High-purity, fine type II anhydrous gypsum can be used, for example, as a raw material for environmentally friendly resin processed products with excellent processing precision. Such gypsum-containing raw materials for resin processed products have no or few impurities, so they are expected to be used in the consumer sector. Furthermore, high-purity, fine type II anhydrous gypsum can be used, for example, as a cement raw material for concrete, which produces a good finish, and increased opportunities for its use are expected. If high-purity, fine type II anhydrous gypsum can be produced from waste gypsum board in this way, the market for this gypsum will expand, leading to an improvement and spread of the recycling environment. Furthermore, if gypsum with a wide range of reuse applications can be easily obtained by innovating a process, barriers to entry will be removed, leading to an improvement and spread of the recycling environment.

[0011] In view of the above, an object of the present invention is to provide a method for recycling waste gypsum board that can efficiently produce high-purity, fine gypsum from waste gypsum board and expand the range of uses for the gypsum obtained from the waste gypsum board, a method for producing a raw material for a resin processed product using the waste gypsum board, and a method for producing a raw material for cement using the waste gypsum board. [Means for solving the problem]

[0012] The present invention relates to the following [1] to [4].

[0013] [1] A first crushing and separation process in which waste gypsum board including a gypsum core material and paper attached to the gypsum core material is crushed and the gypsum core material is crushed to separate an intermediate gypsum powder from the paper; A heating step of heating the intermediate gypsum powder to convert it into type II anhydrous gypsum and burning off residues containing paper and / or plastic contained in the intermediate gypsum powder; The method for recycling waste gypsum board includes a second crushing and separation process in which the intermediate gypsum powder obtained after the heating process is crushed into fine gypsum powder by an airflow crusher, and a residue material including sand contained in the intermediate gypsum powder is separated from the fine gypsum powder by a classification section of the airflow crusher.

[0014] [2] A first crushing and separation process in which waste gypsum board including a gypsum core material and paper attached to the gypsum core material is crushed and the gypsum core material is crushed to separate an intermediate gypsum powder from the paper; A heating step of heating the intermediate gypsum powder to convert it into type II anhydrous gypsum and burning off residues containing paper and / or plastic contained in the intermediate gypsum powder; A second crushing and separating step in which the intermediate gypsum powder after the heating step is crushed into fine gypsum powder by an airflow crusher, and a residue containing sand contained in the intermediate gypsum powder is separated from the fine gypsum powder by a classification unit of the airflow crusher. A method for producing a resin processed raw material using waste gypsum board, comprising: a raw material production step of producing a resin processed raw material by mixing the fine gypsum powder with a resin composition.

[0015] [3] A first crushing and separation process in which waste gypsum board including a gypsum core material and paper attached to the gypsum core material is crushed and the gypsum core material is crushed to separate an intermediate gypsum powder from the paper; A heating step of heating the intermediate gypsum powder to convert it into type II anhydrous gypsum and burning off residues containing paper and / or plastic contained in the intermediate gypsum powder; A second crushing and separating step in which the intermediate gypsum powder after the heating step is crushed into fine gypsum powder by an airflow crusher, and a residue containing sand contained in the intermediate gypsum powder is separated from the fine gypsum powder by a classification unit of the airflow crusher. A method for manufacturing a cement raw material using waste gypsum board, comprising: a raw material manufacturing step of manufacturing a cement raw material by mixing the fine gypsum powder with lime.

[0016] [4] Type II anhydrous gypsum obtained from waste gypsum board, in which the particle size distribution of 80% or more of the components is 50 μm or less, the components are non-needle crystals and non-plate crystals, and the Type II anhydrous gypsum component accounts for 90% by mass or more of the total. The mass% of the components is determined by wavelength dispersive X-ray fluorescence analysis, and the Type II anhydrous gypsum component is determined as the sum of the Ca component and the S component. [Effects of the Invention]

[0017] According to the present invention, high-purity, fine gypsum can be efficiently produced from waste gypsum boards, and the range of uses for the gypsum obtained from waste gypsum boards can be expanded. [Brief explanation of the drawings]

[0018] [Figure 1] 1 shows a schematic configuration of a recycling system according to one embodiment. [Figure 2] 2 is a flowchart showing the steps of a method for recycling waste gypsum boards using the recycling system shown in FIG. 1. [Figure 3] FIG. 2 is a diagram showing an SEM image of an example of fine gypsum powder produced by the recycling system shown in FIG. 1. [Figure 4] FIG. 2 is a graph showing an example of particle size distribution of fine gypsum powder produced by the recycling system shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the present invention will now be described.

[0020] 1 shows a schematic configuration of a recycling system S used in carrying out a method for recycling waste gypsum boards. The recycling system S includes a first crushing and separating device 1, a heating device 10, and a second crushing and separating device 20.

[0021] The first crushing and separating device 1 includes a hopper 2 that receives waste gypsum board, a crushing unit 3 that crushes the waste gypsum board received by the hopper 2, and a separation unit 4 that separates the crushed pieces crushed by the crushing unit 3. The waste gypsum board includes a gypsum core material and paper attached to the gypsum core material. The crushed pieces crushed by the crushing unit 3 include intermediate gypsum powder obtained by crushing the gypsum core material and paper pieces obtained by crushing or breaking the paper. The separation unit 4 separates the intermediate gypsum powder from the paper, for example, by vibrating a sieve.

[0022] The particle size of the intermediate gypsum powder pulverized in the first crushing and separating device 1 is not particularly limited, and the intermediate gypsum powder may be crushed in a relatively coarse state (with large variations in particle size). The particle size of the intermediate gypsum powder may be, for example, 15 mm or less, or may be about 5 mm or less. However, since the intermediate gypsum powder is crushed finely in the first crushing and separating device 1, the processing by the second crushing and separating device 20 in the subsequent stage can be performed smoothly and accurately, it is desirable that the particle size of the intermediate gypsum powder be about 5 mm or less.

[0023] A general gypsum board crushing device may be adopted as the first crushing and separating device 1. For example, a gypsum board processing system manufactured by Towa Kogyo Co., Ltd. or a gypsum board separator manufactured by Hosoda Kikaku Co., Ltd. may be adopted as the first crushing and separating device 1. However, the specific configuration of the first crushing and separating device 1 is not particularly limited.

[0024] The heating device 10 heats the intermediate gypsum powder pulverized in the first pulverizing and separating device 1. The heating device 10 heats the intermediate gypsum powder to convert it into type II anhydrous gypsum, and also performs heating to burn off residues including paper and / or plastic contained in the intermediate gypsum powder.

[0025] The intermediate gypsum powder pulverized in the first pulverizing and separating device 1 is so-called gypsum dihydrate (CaSO4·2H2O). In order to reliably convert the gypsum dihydrate into type II anhydrous gypsum and to reliably burn off the paper and plastic contained in the intermediate gypsum powder, heating at a high temperature is required. Therefore, it is preferable that the heating device 10 be capable of heating the intermediate gypsum powder to 700°C or higher, preferably 800°C or higher. However, the heating temperature is not particularly limited as long as the gypsum dihydrate can be reliably converted into type II anhydrous gypsum.

[0026] A kiln (rotary kiln) may be adopted as the heating device 10. However, the specific configuration of the heating device 10 is not particularly limited, and other furnaces or kilns may also be adopted.

[0027] The second crushing and separating device 20 is a device that receives and crushes the intermediate gypsum powder heated by the heating device 10. The second crushing and separating device 20 is composed of an airflow crusher having a classification function.

[0028] In detail, the second crushing and separating device 20 includes an inlet 21 for receiving intermediate gypsum powder, a fine crushing section 22 for crushing the intermediate gypsum powder received from the inlet 21 into fine gypsum powder, a classification section 23 for separating components having a larger particle size from the fine gypsum powder crushed by the fine crushing section 22, a collection section 24 for collecting the larger particle size components separated by the classification section 23, and an outlet 25 for removing the fine gypsum powder.

[0029] The fine pulverization unit 22 includes a rotor with blades, and the swirling flow of the rotating rotor breaks up the intermediate gypsum powder and causes the intermediate gypsum powder to collide with itself, thereby pulverizing the intermediate gypsum powder into a fine state. The classifier 23 separates the fine gypsum powder pulverized in the fine pulverization unit 22 from the residue, including sand, contained in the intermediate gypsum powder. In this embodiment, the classifier 23 has a structure that allows the fine gypsum powder pulverized in the fine pulverization unit 22 to pass downstream and forms a clearance that restricts the downstream passage of components with particle sizes larger than the fine gypsum powder. In this structure, components that are restricted from passing by the classifier 23 are either pulverized again by the fine pulverization unit 22 or drop out of the fine pulverization unit 22 and accumulate below the rotor of the fine pulverization unit 22. In particular, components that cannot be pulverized into fine gypsum powder gradually accumulate below the rotor. However, the classifying section 23 may also have a structure that uses, for example, air drag and centrifugal force to move residues radially outward and discharge fine gypsum powder in the rotor axial direction.

[0030] The present invention envisions obtaining fine gypsum powder from intermediate gypsum powder, in which 80% or more of the components in the particle size distribution have particle sizes of 50 μm or less, preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. To achieve this fine pulverization, the second pulverization / separation device 20 adjusts the rotation speed, classification clearance, raw material input amount (input amount of intermediate gypsum powder), air volume, and other parameters. When the above particle size distribution is achieved, the particle sizes of most of the components in the fine gypsum powder are 20 μm or less. Here, sand particle sizes are generally approximately 20 μm to 2 mm. When pulverization and classification are performed with the above particle size distribution in mind, the residue, including sand, can be accurately separated from the fine gypsum powder by the classifier 23. This can prevent residue from being mixed into the fine gypsum powder.

[0031] To obtain fine gypsum powder with the above particle size distribution, the classification clearance in the classification section 23 of the second crushing and separating device 20 in this embodiment is set to between 1.5 μm and 3.0 mm, preferably between 1.5 mm and 2.5 mm, more preferably between 1.75 mm and 2.25 mm, specifically 2 mm in this example. Such clearance is set to accurately separate residues containing sand. Specifically, the above particle size distribution is considered excessive in consideration of the applications of the fine gypsum powder described below (resin processing, cement, etc.). However, fine gypsum powder with a larger particle size can also be sufficiently practical, and the classification clearance may be larger than the above range. However, to efficiently perform both the fine particle size reduction and the removal of residues containing sand, it is desirable to set the classification clearance to between 1.5 μm and 3.0 mm, preferably between 1.5 mm and 2.5 mm, more preferably between 1.75 mm and 2.25 mm, specifically 2 mm in this example. However, the classification clearance value is not particularly limited.

[0032] Furthermore, the fine gypsum powder pulverized by the fine pulverizing section 22 of the second pulverizing / separating device 20, which is an airflow pulverizer, loses its needle-like or plate-like crystal form and tends to become fine granules.

[0033] In this embodiment, the residue separated in the classification unit 23 is not circulated as in a general airflow pulverizer, but is collected by the collection unit 24. This can prevent the residue from being mixed into the fine gypsum powder that is finally extracted from the extraction port 25. However, the residue collected in the collection unit 24 also contains gypsum components, which may be re-introduced into the inlet 21 for effective use. In this case, it is desirable to remove sand from the residue before re-introducing it into the inlet 21. Furthermore, when extracting the fine gypsum powder from the extraction port 25, applying vibration to the extraction port 25 makes it easier to extract the fine gypsum powder. Although not shown, a vibration generator is provided at the extraction port 25, and vibration is applied at a predetermined frequency.

[0034] As the second crushing and separating device 20, various airflow crushers can be adopted, but a collection section 24 is additionally provided. As the second crushing and separating device 20, for example, a Serenmirror MKCL8-20 (registered trademark) manufactured by Masuko Sangyo Co., Ltd. may be used.

[0035] 2 is a flowchart showing the steps of the method for recycling waste gypsum boards by the recycling system S. The steps of the method for recycling waste gypsum boards according to this embodiment will be described in detail below.

[0036] First, in step S1, a first crushing and separation process is performed in which waste gypsum board containing a gypsum core material and paper attached to the gypsum core material is crushed and the gypsum core material is crushed to separate intermediate gypsum powder from paper pieces. In this example, the first crushing and separation process is performed by crushing the intermediate gypsum powder so that 80% or more of the components of the intermediate gypsum powder have particle sizes of 5 mm or less. In this example, the first crushing and separation process is performed using a gypsum board separator manufactured by Hosoda Kikaku Co., Ltd. as the first crushing and separation device 1.

[0037] In step S2, the intermediate gypsum powder obtained in the first crushing and separation process is heated by the heating device 10 to convert it into type II anhydrous gypsum, and a heating process is performed in which residues including paper and / or plastic contained in the intermediate gypsum powder are burned off. In this example, the intermediate gypsum powder is heated at 800°C or higher for 3 hours or more. In this example, a kiln (rotary kiln) is used as the heating device 10 to perform the heating process.

[0038] In step S3, a second crushing and separation process is carried out in which the intermediate gypsum powder after the heating process is crushed and the residue is separated. Specifically, in the second crushing and separation process, the intermediate gypsum powder is crushed into fine gypsum powder by a second crushing and separation device 20, which is an airflow crusher, and the residue, including sand contained in the intermediate gypsum powder, is separated by a classifying unit 23, and further collected and separated from the fine gypsum powder.

[0039] In the second crushing and separation process, foreign matter (residue) is removed at the same time as the intermediate gypsum powder is crushed, so the desired high-purity fine gypsum powder can be extracted efficiently and easily, and the takt time can be significantly reduced compared to using a sieve, for example.

[0040] FIG. 3(A) shows an SEM image of an example of fine gypsum powder produced by the recycling system S (produced by step S3 above). It can be seen from FIG. 3 that the fine gypsum powder is a non-acicular, non-plate-like crystal, and is in the form of fine granules. Furthermore, as is clear from comparison with the scale in FIG. 3, the particle diameters of many components of the fine gypsum powder are 10 μm or less. Meanwhile, FIG. 3(B) is an SEM image of an example of gypsum powder after pulverization by the first crushing and separating device 1 and before heating. In the state of FIG. 3(B), many linear crystals remain in the gypsum powder, and the particle diameters are large, with many of them forming clumps.

[0041] Table 1 below shows the measurement results of the particle size distribution of the fine gypsum powder generated by the recycling system S. Table 1 below shows the measurement results when pulverization was performed using two different operation patterns, first and second. The difference between the first operation pattern and the second operation pattern is the amount of intermediate gypsum powder added, which was 2.00 kg in the former and 3.46 kg in the latter.

[0042] [Table 1]

[0043] On the other hand, the following Table 2 shows, as a comparative example, the particle size distribution of gypsum powder when the first pulverization and separation step and the second pulverization and separation step were performed without performing the heating step.

[0044] [Table 2]

[0045] As shown in Table 2, the gypsum powder according to the comparative example contains only about half of the components with particle sizes of 20 μm or less, and also contains components with significantly larger particle sizes. In the comparative example, heating was performed after the second crushing and separation process to convert the gypsum powder into type II anhydrous gypsum. However, the resulting type II anhydrous gypsum is expected to have large particle sizes and contain some that retain the morphology of needle-like or plate-like crystals. Therefore, the characteristics of type II anhydrous gypsum obtained according to the comparative example are expected to be significantly different from the characteristics of the fine gypsum powder obtained according to the present embodiment. In the comparative example, the absence of a heating process before the second crushing and separation process presumably caused plastic to adhere to the rotor of the fine crushing section 22, preventing the expected fine crushing.

[0046] FIG. 4(A) shows a graph representing the particle size distribution shown in Table 1, and FIG. 4(B) shows a graph representing the particle size distribution shown in Table 2. The line indicated by symbol A in FIG. 4(A) shows the particle size distribution of the fine gypsum powder pulverized using the first operation pattern, and the line indicated by symbol B shows the particle size distribution of the fine gypsum powder pulverized using the second operation pattern. The line indicated by symbol C in FIG. 4(B) shows the particle size distribution of the gypsum powder of the comparative example. As is clear from FIGS. 4(A) and (B), the pulverization process according to this embodiment can stably produce fine gypsum powder of 10 μm or less.

[0047] 2, the fine gypsum powder produced in step S3 may be mixed with a resin composition in step S10, for example. Thereafter, a resin processed material containing the fine gypsum powder and the resin composition may be produced in step S11. The resin processed material produced here may be a simple mixture of the fine gypsum powder and the resin composition, or may be produced as pellets obtained by mixing the fine gypsum powder in the resin composition and hardening it.

[0048] The resin composition of the resin processed material is not particularly limited, but a thermoplastic resin is preferable. For example, the resin composition may be any one of polyolefin resins such as polypropylene, high-density polyethylene, and low-density polyethylene, vinyl resins such as polyvinyl chloride, and polyester resins such as polyethylene terephthalate, or a mixture of two or more of these. The resin composition may also be a thermosetting resin, a photocurable resin, or the like.

[0049] The resin processed material as described above may be used as a molding material for a resin processed product in step S12. For example, the resin processed material can be formed into a resin processed product by being melted and then cured.

[0050] The fine gypsum powder produced in step S3 may be mixed with lime in step S20. Then, a cement raw material containing the fine gypsum powder and lime may be produced in step S21. The cement raw material may then be used as a raw material for concrete in step S22.

[0051] Furthermore, the fine gypsum powder generated in step S3 may be used in fields other than resin processed products and cement raw materials (for example, the medical field and the food field) (see FIG. 1). The fine gypsum powder obtained by this embodiment has high purity and therefore may be utilized in the medical and food fields.

[0052] In the recycling method for waste gypsum board according to the present embodiment described above, in the heating step (step S2), the intermediate gypsum powder is converted into type II anhydrous gypsum, and the residue, including paper and / or plastic, contained in the intermediate gypsum powder is burned. During this process, impurities are removed. Furthermore, in the subsequent second crushing and separation step (step S3), foreign matter (residue) is removed simultaneously with the crushing of the intermediate gypsum powder. Therefore, the desired high-purity fine gypsum powder is efficiently and easily extracted, and the takt time can be significantly reduced compared to, for example, using a sieve. Therefore, high-purity, fine gypsum powder can be easily obtained. Furthermore, in the second crushing and separation step (step S3), the intermediate gypsum powder from which the plastic has been burned in the heating step is crushed. This prevents plastic from adhering to the rotor of the fine crushing unit 22, etc., and therefore the crushing process is performed efficiently and in a desired state, further extending the life of the equipment and reducing the maintenance load.

[0053] Therefore, according to the method for recycling waste gypsum boards of this embodiment, high-purity, fine gypsum can be efficiently produced from waste gypsum boards, and the range of uses for the gypsum obtained from waste gypsum boards can be expanded.

[0054] The fine gypsum powder obtained by the method for recycling waste gypsum board according to this embodiment can be used, for example, as a raw material for resin processed products. In this case, the fine gypsum powder is type II anhydrous gypsum and does not change to gypsum hemihydrate, making it effective for long-term storage of the raw material for resin processed products. Furthermore, because it is fine (and is not a needle-like crystal or a plate-like crystal), it does not affect the shape of the finished product, for example, when molding the resin processed product by heating. This allows the production of high-quality resin processed products, expanding their applications.

[0055] Furthermore, the fine gypsum powder obtained by the method for recycling waste gypsum board according to this embodiment can be used, for example, as a cement raw material. In this case, the fine gypsum powder is type II anhydrous gypsum and does not change to gypsum hemihydrate, making it effective for long-term storage of cement raw materials. Furthermore, because it is fine (and because it is not a needle-shaped crystal or a plate-shaped crystal), when concrete is produced, it is possible to avoid the inclusion of air bubbles or voids in the concrete, and it is possible to provide concrete with a good finish.

[0056] The fine gypsum powder obtained by the method for recycling waste gypsum board according to this embodiment loses its needle-like or plate-like crystal form. In other words, the fine gypsum powder is neither needle-like nor plate-like, and becomes fine granules. This makes it easier to mix with the resin composition and lime, and it is noteworthy that this improves the quality of the final product. [Explanation of symbols]

[0057] 1...first crushing and separating device, 2...hopper, 3...crushing section, 4...separating section, 10...heating device, 20...second crushing and separating device, 21...feeding port, 22...fine crushing section, 23...classifying section, 24...collecting section

Claims

1. A first crushing and separating process of crushing waste gypsum board including a gypsum core material and paper attached to the gypsum core material, and separating the gypsum core material into intermediate gypsum powder and the paper; A heating step of heating the intermediate gypsum powder at 800°C or higher to convert it into type II anhydrous gypsum and burning off residues containing paper and / or plastic contained in the intermediate gypsum powder; A second crushing and separating step in which the intermediate gypsum powder after the heating step is crushed into fine gypsum powder by an airflow crusher, and a residue containing sand contained in the intermediate gypsum powder is separated from the fine gypsum powder by a classification unit of the airflow crusher. A raw material preparation step of preparing a resin processed raw material by mixing the fine gypsum powder with a resin composition, The fine gypsum powder after the second crushing and separation step has a particle size distribution in which 80% or more of the components have a particle size of 10 μm or less, and is a non-needle crystal and a non-plate crystal.

2. The method for recycling waste gypsum board according to claim 1, wherein the resin processed raw material is produced as pellets by containing the fine gypsum powder in the resin composition and hardening the resin composition.

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