Recycling method for waste gypsum board, method for producing resin workpiece raw material using waste gypsum board, method for producing cement raw material 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 the waste gypsum board, a method for producing a raw material for a cement using the waste gypsum board, and type II anhydrite obtained from the 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 a building is enormous, and is expected to increase in the future.

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

[0004] Currently, waste gypsum boards are landfilled at controlled industrial waste disposal sites. However, there is a limit to the amount of land available for such 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. For these reasons, various techniques 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] JP 2023-36207 A [Patent Document 2] JP 2023-36205 A [Patent Document 3] JP 2022-24689 A [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 boards (remanufacturing gypsum boards and as a solidifying agent) are currently very limited. In other words, the market is limited, and many companies are reluctant 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-shaped crystals. In other words, these characteristics and properties place restrictions on the uses for recycling, making it difficult to expand the market (uses). (3) The gypsum extracted from the current waste gypsum board still contains a certain amount of foreign matter, such as sand and plastic, which can cause undesirable effects, for example, on the environmental front, 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 conducted intensive research in light of the above circumstances and discovered that by improving the properties of the gypsum extracted from waste gypsum boards and the manufacturing process, its uses could be expanded.

[0009] Specifically, the inventors have discovered that by converting the gypsum extracted from waste gypsum boards 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 dramatically expanding the uses of the gypsum extracted from waste gypsum boards.

[0010] High-purity, fine anhydrous gypsum type II can be used, for example, as a raw material for resin processed products that are environmentally friendly and have excellent processing accuracy. Such raw materials for resin processed products containing gypsum contain no or few impurities, so they can be expected to be used in the civilian field. In addition, high-purity, fine anhydrous gypsum type II can be used, for example, as a cement raw material for concrete that has a good finish, and the opportunities for its use are expected to increase. If high-purity, fine anhydrous gypsum type II is produced from waste gypsum board in this way, the market for the gypsum will expand, which will lead to the improvement and spread of the recycling environment. Furthermore, if gypsum that can be reused in a wider range of applications can be easily obtained by ingenuity in the process, the barrier to entry will be removed, leading to the 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 for 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 to convert it into type II anhydrous gypsum and burning off residues including paper and / or plastic contained in the intermediate gypsum powder; The method for recycling waste gypsum boards includes a second crushing and separation process in which the intermediate gypsum powder after the heating process is crushed into fine gypsum powder by an airflow crusher, and a residue 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 for 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 to convert it into type II anhydrous gypsum and burning off residues including 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 section 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 for 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 to convert it into type II anhydrous gypsum and burning off residues including 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 section of the airflow crusher; A method for producing a cement raw material using waste gypsum board, comprising: a raw material production process for producing 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 of 80% or more of the components in the particle size distribution is 50 μm or less, the particles are non-needle crystals and non-plate crystals, and the type II anhydrous gypsum component is 90% by mass or more of the total. The mass% of the components is a value determined by wavelength dispersive X-ray fluorescence analysis, and the type II anhydrous gypsum component is determined by the combined Ca component and S component. Effect 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 description of the drawings]

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

[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 / separating device 1, a heating device 10, and a second crushing / separating device 20.

[0021] The first crushing and separating device 1 includes a hopper 2 that receives waste gypsum boards, a crushing section 3 that crushes the waste gypsum boards received by the hopper 2, and a separation section 4 that separates the crushed pieces crushed by the crushing section 3. The waste gypsum boards include a gypsum core material and paper attached to the gypsum core material. The crushed pieces crushed by the crushing section 3 include intermediate gypsum powder obtained by crushing the gypsum core material, and paper pieces obtained by crushing or breaking the paper. The separation section 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 pulverized in a relatively coarse state (state in which the particle size varies widely). The particle size of the intermediate gypsum powder may be, for example, 15 mm or less, or about 5 mm or less. However, since the processing by the second crushing and separating device 20 in the subsequent stage can be performed smoothly and accurately if the intermediate gypsum powder is finely crushed in the first crushing and separating device 1, 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 / 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 / separating device 1. However, the specific configuration of the first crushing / separating device 1 is not particularly limited.

[0024] The heating device 10 heats the intermediate gypsum powder pulverized in the first crushing 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. For this reason, it is preferable that the heating device 10 is capable of heating the intermediate gypsum powder to 700°C or higher, and preferably 800°C or higher. However, as long as the gypsum dihydrate can be reliably converted into type II anhydrous gypsum, the heating temperature is not particularly limited.

[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 ovens may be adopted.

[0027] The second crushing and separating device 20 is a device that receives the intermediate gypsum powder heated by the heating device 10 and crushes it. The second crushing and separating device 20 is composed of an airflow type 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 in 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 pulverizing section 22 includes a rotor with blades, and the intermediate gypsum powder is pulverized into a fine state by dividing the intermediate gypsum powder with a swirling flow caused by the rotating rotor or by colliding the intermediate gypsum powder with itself. The classification section 23 separates the fine gypsum powder pulverized in the fine pulverizing section 22 from the residue containing sand contained in the intermediate gypsum powder. In this embodiment, the classification section 23 has a structure that allows the fine gypsum powder pulverized in the fine pulverizing section 22 to pass downstream and forms a clearance that restricts the passage of components with a particle size larger than that of the fine gypsum powder downstream. In this structure, the components whose passage is restricted by the classification section 23 are pulverized again by the fine pulverizing section 22 or drop out of the fine pulverizing section 22 and are accumulated below the rotor of the fine pulverizing section 22. In particular, components that cannot be pulverized into fine gypsum powder are sequentially accumulated below the rotor. However, the classifying section 23 may also have a structure in which, for example, air resistance and centrifugal force are applied to move the residue radially outward and discharge the fine gypsum powder in the rotor axial direction.

[0030] In the present invention, it is assumed that fine gypsum powder in which the particle diameter of 80% or more of the components in the particle diameter distribution is 50 μm or less, preferably 25 μm or less, more preferably 20 μm or less, and further preferably 10 μm or less is obtained from the intermediate gypsum powder. In order to enable such fine pulverization, the second pulverization and separation device 20 adjusts the rotation speed, classification clearance, raw material input amount (input amount of intermediate gypsum powder), air volume, etc. In the case of the above-mentioned particle diameter distribution, the particle diameter of many components in the fine gypsum powder is 20 μm or less. Here, the particle diameter of sand is generally about 20 μm to 2 mm, and when pulverization and classification are performed with the above-mentioned particle diameter distribution in mind, the residue containing sand can be accurately separated from the fine gypsum powder by the classification unit 23. This can suppress the state in which the residue is mixed into the fine gypsum powder.

[0031] When obtaining fine gypsum powder having the above-mentioned particle size distribution, in the classification section 23 of the second crushing and separating device 20 in this embodiment, the classification clearance is set 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 a clearance is set to accurately separate the residue containing sand. In detail, the above-mentioned particle size distribution has an aspect of over-specification in consideration of the later-described uses of the fine gypsum powder (resin processing, cement, etc.), and fine gypsum powder with a larger particle size can also be sufficiently practical, and the classification clearance may be larger than the above-mentioned range. However, in order to efficiently proceed with the refinement and the removal of the residue containing sand at the same time, it is desirable to set the classification clearance 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 by the classification unit 23 is not circulated as in a general airflow type pulverizer, but is collected by the collection unit 24. This can suppress the inclusion of residue in the fine gypsum powder finally taken out from the outlet 25. However, the residue collected by the collection unit 24 also contains gypsum components, which may be re-introduced into the inlet 21 in order to make effective use of them. In this case, it is preferable to remove sand from the residue and then re-introduce it into the inlet 21. In addition, when the fine gypsum powder is taken out from the outlet 25, applying vibration to the outlet 25 makes it easier to take out the fine gypsum powder. Although not shown, a vibration generator is provided at the outlet 25, and vibration is applied at a predetermined period.

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

[0035] 2 is a flow chart 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 intermediate gypsum powder obtained by crushing the gypsum core material is separated from paper pieces. In this example, in the first crushing and separation process, the intermediate gypsum powder is crushed so that 80% or more of the components of the intermediate gypsum powder are 5 mm or less in the particle size distribution of the intermediate gypsum powder. 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 to burn off residues including paper and / or plastic contained in the intermediate gypsum powder. 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 performed in which the intermediate gypsum powder after the heating process is crushed and the residue is separated. In the second crushing and separation process, more specifically, 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 classification 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 tact time can be significantly reduced compared to when 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). In FIG. 3, it can be seen that the fine gypsum powder is a non-acicular crystal and a non-plate-like crystal, and is in the form of fine granules. In addition, as is clear from comparison with the scale in FIG. 3, the particle diameter of many components of the fine gypsum powder is 10 μm or less. On the other hand, FIG. 3(B) is an SEM image of an example of gypsum powder after being crushed by the first crushing and separating device 1 and before being heated. In the state of FIG. 3(B), many linear crystals remain in the gypsum powder, the particle diameter of which is large, and many of them are in the form of clumps.

[0041] Table 1 below shows the measurement results of the particle size distribution of the fine gypsum powder generated by the recycle system S. Table 1 below shows the measurement results when grinding was performed using two different operation patterns, first and second. The difference between the first and second operation patterns is the amount of intermediate gypsum powder fed, 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 / separation step and the second pulverization / 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 a particle size of 20 μm or less, and also contains components with a fairly large particle size. In the comparative example, it was assumed that the gypsum powder was converted into type II anhydrous gypsum by heating after the second crushing and separation process, but it is assumed that the obtained type II anhydrous gypsum has a large particle size and contains those that maintain the shape of needle crystals or plate crystals. Therefore, it is assumed that the characteristics of type II anhydrous gypsum obtained based on the comparative example are significantly different from the characteristics of the fine gypsum powder obtained by the present embodiment. In the comparative example, it is presumed that the heating process was not performed before the second crushing and separation process, and therefore the plastic adhered to the rotor of the fine crushing unit 22, and the expected fine crushing was not performed due to such an event.

[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 the symbol A in FIG. 4(A) shows the particle size distribution of the fine gypsum powder pulverized by the first operation pattern, and the line indicated by the symbol B shows the particle size distribution of the fine gypsum powder pulverized by the second operation pattern. The line indicated by the 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 makes it possible to stably obtain 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. After that, a resin processed raw material containing the fine gypsum powder and the resin composition may be produced in step S11. The resin processed raw material produced here may be a simple mixture of the fine gypsum powder and the resin composition, or may be produced as pellets by incorporating the fine gypsum powder in the resin composition and hardening it.

[0048] The resin composition in the raw material of the resin processed product 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, 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 above-mentioned resin processed material raw material may be used as a molding raw material for a resin processed product in step S12. For example, the resin processed raw material can be melted and then cured to form a resin processed product.

[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] 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 in this embodiment has high purity and therefore may be utilized in the medical and food fields.

[0052] In the recycling method of 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 residues including paper and / or plastic contained in the intermediate gypsum powder are burned. At this time, impurities are removed. Furthermore, in the subsequent second crushing and separation step (step S3), foreign matter (residues) is removed at the same time as the intermediate gypsum powder is crushed, so that the desired fine gypsum powder of high purity is efficiently and easily extracted, and the tact time can be significantly reduced compared to the case of using a sieve, for example. Therefore, high-purity and fine fine gypsum powder can be easily obtained. In addition, 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, so that the adhesion of plastic to the rotor of the fine crushing section 22 and the like is suppressed, and the crushing process is performed efficiently and in a desired state, and further the life of the device is extended and the maintenance load is reduced.

[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 the waste gypsum boards can be expanded.

[0054] The fine gypsum powder obtained by the method for recycling waste gypsum board according to the present 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 hemihydrate gypsum, so it is effective for long-term storage of the raw material for resin processed products. In addition, since it is fine (and furthermore, since it is not a needle-like crystal or a plate-like crystal), it does not affect the shape of the finished product, for example, when the resin processed product is molded by heating. This allows the production of high-quality resin processed products, expanding the range of applications.

[0055] Furthermore, the fine gypsum powder obtained by the method for recycling waste gypsum board according to the present 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 hemihydrate gypsum, so it is effective for long-term storage of cement raw materials. In addition, because it is fine (and further because it is not needle-shaped or plate-shaped crystals), when concrete is produced, it is possible to avoid a situation in which air bubbles or voids are contained in the concrete, and it is possible to provide concrete with a good finish.

[0056] The fine gypsum powder obtained by the recycling method of waste gypsum board according to the present embodiment loses the form of needle-like crystals or plate-like crystals. In other words, the fine gypsum powder is non-needle-like crystals and non-plate-like crystals, and becomes fine granular material. This makes it easier to mix with the resin composition and lime, and it is noteworthy that the quality of the final product is improved. [Explanation of symbols]

[0057] Reference Signs List 1: first crushing and separating device, 2: hopper, 3: crushing section, 4: separating section, 10: heating device, 20: second crushing and separating device, 21: inlet, 22: fine crushing section, 23: classifying section, 24: collecting section

Claims

1. A first crushing and separation process of crushing a waste gypsum board including a gypsum core material and paper attached to the gypsum core material, and separating the gypsum core material into an intermediate gypsum powder and the paper; A heating step of heating the intermediate gypsum powder to convert it into type II anhydrous gypsum and burning off residues including 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 after the heating process 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 section of the airflow crusher.

2. A first crushing and separation process of crushing a waste gypsum board including a gypsum core material and paper attached to the gypsum core material, and separating the gypsum core material into an intermediate gypsum powder and the paper; A heating step of heating the intermediate gypsum powder to convert it into type II anhydrous gypsum and burning off residues including 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 section 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.

3. A first crushing and separation process of crushing a waste gypsum board including a gypsum core material and paper attached to the gypsum core material, and separating the gypsum core material into an intermediate gypsum powder and the paper; A heating step of heating the intermediate gypsum powder to convert it into type II anhydrous gypsum and burning off residues including 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 section of the airflow crusher; A method for producing a cement raw material using waste gypsum board, comprising: a raw material production process for producing a cement raw material by mixing the fine gypsum powder with lime.

4. A type II anhydrous gypsum obtained from waste gypsum board, in which 80% or more of the components in the particle size distribution have particle sizes of 50 μm or less, 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.

Images