Pulverization processing device

Abstract

To provide a pulverization processing device which can easily pulverize various materials with a simple structure.SOLUTION: A pulverization processing device 1 includes a pulverizing part 10 which pulverizes a material by rubbing a first rubbing member 11 and a second rubbing member 12, in each of which a plurality of projections 13 extending in a radial direction are formed on at least a part of a facing surface, with each other. For example, the pulverizing part 10 is configured so that at least one of the first rubbing member 11 and the second rubbing member 12 is rotated to cause the facing surfaces to rub with each other. A material supply port 14 is provided at a center part of the first rubbing member 11 or a center part of the second rubbing member 12. Further, the pulverizing part 10 can be cooled by cooling means.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a fine grinding device for finely grinding a material. [Background technology]

[0002] In recent years, the importance of advanced material recycling has been increasing in order to build a resource-circulating society. However, at recycling sites, it is rare to handle waste plastics that are completely free of impurities, and it is usually necessary to mix multiple plastic materials that do not mix, inorganic minerals, additives, etc. "Pseudo-compatibility" is a measure of "whether or not they are mixed," and the degree of dispersion (size of dispersed particles) in a polymer mixture system is a guide to judging pseudo-compatibility. For plastic raw materials, processing them into a finer state will increase pseudo-compatibility and enable high-quality recycling, so there is a demand for the development of equipment that enables fine pulverization.

[0003] For example, Patent Document 1 shows equipment that uses the rotation of a rotary blade to further finely crush flake-like waste plastics. Also, for example, Non-Patent Document 1 shows a method called freeze crushing, in which raw materials are immersed in liquid nitrogen at -196°C to embrittle them, thereby crushing rubber and resins that are difficult to crush at room temperature. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5459888 [Non-patent literature]

[0005] [Non-Patent Document 1] Seishin Enterprise Co., Ltd. Frozen Grinding Brochure (https: / / www.betterseishin.co.jp / wp-ontent / uploads / 2018 / 11 / resin_powder_processing.pdf) Summary of the Invention [Problem to be solved by the invention]

[0006] However, while the method described in Patent Document 1 is capable of finely pulverizing plastics with high melting points, such as flake-like polyethylene terephthalate (PET) resin, there is a problem in that it is difficult to use with resins with low melting points and elasticity, such as polyethylene (PE) and polypropylene (PP), as they become kneaded inside the crusher.

[0007] In addition, the method described in Reference 2 can produce fine powder of elastic resins with low melting points such as PE and PP, but it is necessary to freeze the raw materials in advance by immersing them in liquid nitrogen, and the equipment itself needs to be made of metal and designed to withstand conditions in which it will come into contact with liquid nitrogen when operating, which poses the problem of high labor, equipment, and run costs making it unprofitable.

[0008] The present invention has been made in view of the above problems, and has an object to provide a fine pulverizing apparatus capable of easily pulverizing various materials with a simple configuration. [Means for solving the problem]

[0009] The fine grinding processing device of the present invention finely grinds waste material containing resin, and is equipped with a crushing section that crushes the material by grinding a first grinding member and a second grinding member, each of which has a plurality of protrusions extending radially from at least a portion of the opposing surfaces, a material supplying means that supplies the material to the crushing section, a recovery means that recovers the crushed material crushed in the crushing section, and a cooling means that cools the crushing section. Effect of the Invention

[0010] According to the present invention, the material is crushed by grinding the first and second grinding members, which are formed with a plurality of protrusions extending in the radial direction. As the material passes quickly between the protrusions of the first and second grinding members while being crushed, the temperature rise of the material can be suppressed, and the occurrence of kneading can be suppressed. In addition, the crushing section is cooled by a cooling means, so that the temperature rise of the material can be further suppressed. Therefore, even resins with low melting points can be finely ground, and various materials can be easily finely ground with a simple configuration.

[0011] In particular, by rotating at least one of the first and second grinding members to cause their opposing surfaces to rub against each other, and by providing a material supply port connected to a material supply means in the center of the first or second grinding member, centrifugal force can be utilized to more quickly pass the material between the protrusions and push it outward.

[0012] Furthermore, by making the spacing between each protrusion of the first and second sliding members within the range of 0.5 mm or more and 0.6 mm or less, the inner width of each protrusion within the range of 0.5 mm or more and 0.6 mm or less, the outer width of each protrusion within the range of 0.9 mm or more and 1.2 mm or less, and the height of each protrusion within the range of 0.8 mm or more and 0.9 mm or less, fine grinding can be easily achieved.

[0013] Furthermore, if the cooling means has a cooling device main body that cools and discharges compressed air, a nozzle attached to the cooling device main body, compressed air supply means that supplies compressed air to the cooling device main body, and piping that guides the compressed air from the compressed air supply means to the cooling device main body, the device can be simplified and effective cooling can be achieved.

[0014] In addition, if a spraying means is provided for spraying water onto the material to be supplied to the pulverizing section, the moisture content on the surface of the material can be increased, thereby further suppressing the temperature rise of the material during fine pulverization.

[0015] Furthermore, if the recovery means is provided with a sieve section and a re-supply pipe for returning the crushed material that did not pass through the sieve section to the crushing section, it is possible to maintain a large processing volume while suppressing the occurrence of kneading and achieving fine crushing. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram showing an overall configuration of a fine pulverization apparatus according to an embodiment of the present invention; [Diagram 2] 2 is a diagram illustrating a schematic configuration of a cross section taken along line II shown in FIG. [Diagram 3] 3 is a diagram illustrating a schematic configuration of a cross section taken along line II-II shown in FIG. 2. [Figure 4] 3 is a diagram illustrating a schematic configuration of a cross section taken along line III-III shown in FIG. 2. [Diagram 5] 4 is an enlarged view of a portion of a cross section taken along line IV-IV shown in FIG. 3. [Figure 6] 2 is a diagram illustrating a part of a cross section taken along line VV shown in FIG. [Figure 7] FIG. 13 is a diagram illustrating a configuration of a modified example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described in detail.

[0018] (One embodiment) FIG. 1 shows the overall configuration of a fine pulverizing apparatus 1 according to an embodiment of the present invention. FIG. 2 shows a schematic configuration of a cross section taken along line II shown in FIG. 1. FIG. 3 shows a schematic configuration of a cross section taken along line II-II shown in FIG. 2. FIG. 4 shows a schematic configuration of a cross section taken along line III-III shown in FIG. 2. FIG. 5 shows an enlarged view of a portion of the cross section taken along line IV-IV shown in FIG. 3. FIG. 6 shows a portion of the cross section taken along line VV shown in FIG. 1.

[0019] This fine pulverizing device 1 is for pulverizing materials, for example, for further pulverizing materials pulverized into flakes. For example, waste materials containing resins are preferable. For example, waste materials containing polyolefin resins such as PE and PP are representative. In addition to polyolefins, materials containing polystyrene (PS) and polyvinyl chloride (PVC), which were difficult to pulverize with conventional pulverizers, can also be used. Furthermore, materials that are difficult to pulverize, such as polyamide (PA) and low-temperature elastomers, may be used in small amounts, for example, 10% by mass or less. In addition, materials containing polyethylene terephthalate (PET), ABS resin, thermosetting resin, engineering plastics, or super engineering plastics, which can be pulverized with conventional pulverizers, can also be used.

[0020] The waste may be made of one type of material or may contain two or more types of materials. For example, it may be a composite film in which at least an olefin-based resin film and another synthetic resin film are laminated together. It may also contain a resin and a material other than resin. Examples of materials other than resin include metal, glass, inorganic additives, ink, and coloring agents. For example, it may be a composite film having a resin film and a metal foil such as aluminum foil, a printed film using printing ink, a colored film using a coloring agent, a resin film to which metal or titanium oxide is added, an optical cable, a plastic product containing ink or a small amount of sand, or a home appliance containing metal. The waste may be used waste material, unused scraps generated in the production process, or unused products such as defective molded products, or a mixture of new material and waste material.

[0021] This fine grinding processing device 1 includes, for example, a grinding section 10 for grinding materials, a material supplying means 20 for supplying materials to the grinding section 10, a recovery means 30 for recovering the ground material ground in the grinding section 10, a cooling means 40 for cooling the grinding section 10, and a spraying means 50 for spraying water onto the materials supplied to the grinding section 10.

[0022] The crushing section 10 is configured to crush materials by grinding the first and second sliding members 11 and 12 together. The first and second sliding members 11 and 12 are made of, for example, cemented carbide or a metal material with a cemented carbide layer formed on the surface. The first and second sliding members 11 and 12 are disposed opposite each other, and a plurality of protrusions 13 extending in the radial direction are formed on at least a part of their opposing surfaces. This allows the material to be crushed while passing quickly between the protrusions 13 of the first and second sliding members 11 and 12. Note that in FIGS. 3 to 5, the configuration of the protrusions 13 is conceptually shown and does not correspond to the actual dimensions.

[0023] The crushing section 10 is preferably configured to rotate at least one of the first and second grinding members 11 and 12 along the opposing surfaces to grind the opposing surfaces together, and a material supply port 14 connected to the material supply means 20 is preferably provided at the center of the first grinding member 11 or the center of the second grinding member 12. This is because the material can be pushed outward by passing between the protrusions 13 more quickly using centrifugal force. In this embodiment, for example, a case will be described in which the first grinding member 11 is rotated, the second grinding member 12 is fixed, and the material supply port 14 is provided at the center of the second grinding member 12.

[0024] In the first mating member 11, a guide area 11A is provided in a region corresponding to the material supply port 14 to guide the material supplied to the material supply port 14 to the outside (i.e., the outer periphery), and a first mating area 11B is provided on the outside of the guide area 11A, in which a protrusion 13 is formed. In the guide area 11A, for example, a plurality of protruding blades 15 extending from the center side to the outside are provided. It is preferable that the blades 15 protrude toward the second mating member 12 side more than the protrusion 13. This is to scrape the material supplied to the material supply port 14 and guide it to the outside. The number of blades 15 is preferably, for example, 2 to 8. On the opposite side of the first mating member 11 to the second mating member 12, a rotating shaft 16 extends from the center, and a driving means 17 such as a motor is connected to the rotating shaft 16. The second mating member 12 is provided with a material supply port 14 in the center, and is provided with a second mating region 12A on the outside of the material supply port 14, where a protrusion 13 is formed in correspondence with the first mating region 11B.

[0025] Each protrusion 13 is preferably configured such that the cross-sectional shape of the surface side in the direction perpendicular to the extending direction is triangular. Specifically, each protrusion 13 is preferably configured such that, for example, one end side adjacent to another protrusion 13 protrudes toward the surface side more than the other end side, and the surface of each protrusion 13 is an inclined surface in which one end side protrudes more than the other end side. Also, each protrusion 13 of the first sliding member 11 and each protrusion 13 of the second sliding member 12 are preferably configured such that, when each protrusion 13 is individually arranged opposite to each other, one end side (i.e., the protruding side) and the other end side (i.e., the non-protruding side) face each other.

[0026] The interval T1 between each of the protrusions 13 is preferably within a range of, for example, 0.5 mm to 0.6 mm. The inner width W1 of each of the protrusions 13 in the radial direction is preferably within a range of, for example, 0.5 mm to 0.6 mm, and the outer width W2 of each of the protrusions 13 in the radial direction is preferably within a range of, for example, 0.9 mm to 1.2 mm. The height (height on the protruding side) H of each of the protrusions 13 is preferably within a range of, for example, 0.8 mm to 0.9 mm. The distance T2 between each of the protrusions 13 of the first sliding member 11 and each of the protrusions 13 of the second sliding member 12 is preferably within a range of, for example, 0.01 mm to 0.5 mm, more preferably within a range of 0.01 mm to 0.03 mm, and even more preferably within a range of 0.01 mm to 0.15 mm. The smaller the spacing T1, widths W1, W2, height H of the protrusions 13, and the distance T2 between each protrusion 13 of the first grinding member 11 and the second grinding member 12, the more finely the powder can be pulverized, but if they are made too small, the processing volume will be reduced and consideration will need to be given to thermal expansion during grinding, etc.

[0027] The first and second mating members 11 and 12 are housed, for example, inside a cover body 18, and the crushed material crushed by the friction between the first and second mating members 11 and 12 is pushed out from the outside into the inside of the cover body 18.

[0028] The material supplying means 20 is disposed, for example, above the material supplying port 14 and has a material constant volume feeder 21 that supplies a predetermined amount of material, and a material supplying pipe 22 that guides the material from the material constant volume feeder 21 to the material supplying port 14. In the material supplying pipe 22, the material moves to the material supplying port 14 by natural drop. The material supplied by the material supplying means 20 is preferably, for example, pulverized into flakes.

[0029] The recovery means 30 has, for example, a temporary storage section 31 for temporarily storing the pulverized material, a guide tube 32 for guiding the pulverized material from the inside of the cover body 18 to the temporary storage section 31, and suction means (not shown) for moving the pulverized material from the cover body 18 to the temporary storage section 31 by suction. The guide tube 32 has, for example, an upper guide tube 32A for guiding the pulverized material from the upper side of the cover body 18 to the temporary storage section 31, and a lower guide tube 32B for guiding the pulverized material from the lower side of the cover body 18 to the temporary storage section 31. The suction means is connected to the temporary storage section 31 via a suction tube 33.

[0030] The recovery means 30 also has, for example, a sieve section 34 for separating the crushed material by size, a crushed material constant-quantity feeder 35 for feeding a predetermined amount of crushed material from the temporary storage section 31 to the sieve section 34, a re-supply pipe 36 for guiding crushed material that does not pass through the sieve section 34 from the sieve section 34 to the material supply port 14 of the crushing section 10, and a discharge section 37 for discharging crushed material that has passed through the sieve section 33.

[0031] The sieve unit 34 is disposed, for example, below the temporary storage unit 31 and above the material supply port 14 of the crushing unit 10. The sieve unit 34 is preferably configured, for example, by a vibration sieve machine, and is preferably a two-stage type. The size of the sieve openings is preferably such that the size of the crushed material passing through the sieve unit 34 is 0.5 mm or less, and more preferably 0.2 mm or less. In the re-supply pipe 36, the crushed material moves to the material supply port 14 by natural fall.

[0032] The cooling means 40 is configured to cool at least one of the first and second mating members 11 and 12 with a cooling medium. In this embodiment, for example, the second mating member 12 is cooled with a cooling medium, and the first mating member 11 is also indirectly cooled, thereby suppressing the temperature rise of the material. Specifically, the cooling means 40 preferably has, for example, a cooling device main body 41 that cools compressed air and discharges the cooled air, a nozzle 42 attached to the cooling air outlet of the cooling device main body 41, a compressed air supplying means 43 such as a compressor that supplies compressed air to the cooling device main body 41, and a pipe 44 that guides the compressed air from the compressed air supplying means 43 to the cooling device main body 41. This is because the device can be simplified and cooling can be performed effectively. In order to make the configuration easier to understand, the cooling means 40 is omitted in Figs. 1 and 2.

[0033] Also, for example, the second mating member 12 and the cover body 18 are provided with a plurality of insertion holes 12B and through holes 18A into which the nozzles 42 of the cooling means 40 are inserted. The insertion holes 12B are, for example, non-through holes, and are preferably provided from the outside of the second mating member 12 to the vicinity of each protrusion 13. The through holes 18A are, for example, provided so as to penetrate the cover body 18 in correspondence with each insertion hole 12B. The insertion holes 12B are, for example, provided at intervals around the material supply port 14, and it is preferable to provide a plurality of types of insertion holes with different distances from the material supply port 14. Note that the drawings of this embodiment show a case in which two insertion holes 12B are arranged on the side of the material supply port 14 and two on the outer periphery side, alternately arranged along the circumferential direction of the material supply port 14. Note that, in order to make the configuration easier to understand, in FIG. 6, the nozzles 42 inserted into the insertion holes 12B on the side of the material supply port 14, and the cooling device main body 41 and piping 44 connected thereto are omitted.

[0034] It is preferable that the cooling means 40 is controlled by a control means (not shown) in response to, for example, the internal temperature of the cover body 18, the temperature of the first mating member 11, or the temperature of the second mating member 12.

[0035] The spraying means 50, for example, sprays water in a mist onto the material, increasing the moisture content on the surface of the material and suppressing the temperature rise of the material during fine grinding. The spraying means 50 is, for example, disposed on the material supply pipe 22. It is preferable to use the spraying means 50 as necessary depending on the type of material to be finely ground.

[0036] The fine pulverizing device 1 operates as follows to pulverize the material. First, for example, the material pulverized into flakes is fed into the material constant quantity feeder 21. The material constant quantity feeder 21 supplies a predetermined amount of material to the material supply port 14 of the pulverizing section 10 via the material supply pipe 22. At this time, if necessary depending on the type of material, water is sprayed onto the material by the spraying means 50. The material supplied to the material supply port 14 is pushed outward by, for example, the rotation of the first grinding member 11 and the rotation of the wing 15 formed in the guide area 11A, and reaches the opposing area of ​​the first grinding area 11B and the second grinding area 12A. In the opposing area of ​​the first grinding area 11B and the second grinding area 12A, the material is pushed outward while being pulverized by, for example, the centrifugal force caused by the rotation of the first grinding member 11 and the air flow caused by the suction means of the recovery means 30. At that time, if necessary depending on the type of material, the crushing section 10 is cooled by the cooling means 40.

[0037] The pulverized material pulverized by the first and second grinding members 11 and 12 is, for example, pushed from the outside thereof into the inside of the cover body 18, and is stored in the temporary storage section 31 via the upper guide tube 32A and the lower guide tube 32B by suction by the suction means of the recovery means 30. A predetermined amount of the pulverized material stored in the temporary storage section 31 is supplied to the sieve section 34 by the pulverized material constant volume feeder 35, and the pulverized material that passed through the sieve section 34 is discharged from the discharge section 37. The pulverized material that did not pass through the sieve section 34 is guided to the material supply port 14 of the pulverizing section 10 via the re-supply tube 36, and is pulverized again in the pulverizing section 10.

[0038] In this manner, according to the present embodiment, the material is crushed by rubbing the first and second sliding members 11 and 12, on which a plurality of projections 13 extending in the radial direction are formed, so that the material is crushed while passing quickly between the projections 13 of the first and second sliding members 11 and 12, thereby suppressing the temperature rise of the material and suppressing the occurrence of kneading. In addition, the crushing section 10 is cooled by the cooling means 40, so that the temperature rise of the material can be further suppressed. Therefore, even resins with a low melting point can be finely crushed, and various materials can be easily finely crushed with a simple configuration.

[0039] In particular, by rotating at least one of the first and second grinding members 11 and 12 so that their opposing surfaces are brought into friction with each other, and by providing a material supply port 14 connected to the material supply means 20 in the center of the first or second grinding member 11 or 12, the material can be made to pass between the protrusions more quickly by utilizing centrifugal force and pushed outward.

[0040] Furthermore, fine grinding can be easily achieved by setting the spacing T between each protrusion 13 of the first and second sliding members 11, 12 within the range of 0.5 mm or more and 0.6 mm or less, the inner width W1 of each protrusion 13 within the range of 0.5 mm or more and 0.6 mm or less, the outer width W2 of each protrusion 13 within the range of 0.9 mm or more and 1.2 mm or less, and the height H of each protrusion 13 within the range of 0.8 mm or more and 0.9 mm or less.

[0041] Furthermore, if the cooling means 40 has a cooling device main body 41 that cools and discharges compressed air, a nozzle 42 attached to the cooling device main body 41, a compressed air supply means 43 that supplies compressed air to the cooling device main body 41, and piping 44 that guides the compressed air from the compressed air supply means 43 to the cooling device main body 41, the device can be simplified and effective cooling can be achieved.

[0042] In addition, if a spraying means 50 for spraying water onto the material supplied to the pulverizing section 10 is provided, the moisture content on the surface of the material can be increased, thereby further suppressing the temperature rise of the material during fine pulverization.

[0043] Furthermore, if the recovery means 30 is provided with a sieve section 34 and a re-supply pipe 36 for returning the pulverized material that did not pass through the sieve section 34 to the pulverization section 10, it is possible to maintain a large processing volume while suppressing the occurrence of kneading and achieving fine pulverization.

[0044] Using the fine pulverizing device 1 described in this embodiment, a plastic container made of injection molding grade polypropylene was prepared as waste containing resin, and finely pulverized. The interval T1 between each protrusion 13 in the pulverizing section 10 was set to 0.5 mm or more and 0.6 mm or less, the inner width W1 of each protrusion 13 in the radial direction was set to 0.5 mm or more and 0.6 mm or less, the outer width W2 of each protrusion 13 in the radial direction was set to 0.9 mm or more and 1.2 mm or less, the height H of each protrusion 13 was set to 0.8 mm or more and 0.9 mm or less, and the distance T2 between each protrusion 13 of the first sliding member 11 and the second sliding member 12 was set to 0.01 mm or more and 0.5 mm or less. The waste containing resin was made into flakes and supplied to the material supplying means 20, and water was sprayed onto the material by the spraying means 50. Furthermore, the fine pulverization was performed while cooling the pulverizing section 10 by the cooling means 40.

[0045] As a result, no resin was found to be mixed in the fine pulverizing device 1, and pulverized material having a size of 0.5 mm or less was obtained.

[0046] (Modification) In the above embodiment, the cooling device main body 41 that cools compressed air and discharges cooled air is used as the cooling means 40, but as shown in Fig. 7, for example, a refrigerant flow passage 45 for circulating a cooling medium such as water may be provided inside at least one of the first and second sliding members 11 and 12, and the cooling medium may be cooled by a heat exchanger (not shown) and circulated. Fig. 7 shows a case where the refrigerant flow passage 45 is provided inside the second sliding member 12. Even with such a configuration, the same actions and effects as those of the above embodiment can be obtained.

[0047] Although the present invention has been described above with reference to the embodiment, the present invention is not limited to the above embodiment and can be modified in various ways. For example, in the above embodiment, each component is specifically described, but it is not necessary to include all the components, and other components may be included.

[0048] In the above embodiment, the first sliding member 11 is rotated and the second sliding member 12 is fixed, but both the first sliding member 11 and the second sliding member 12 may be rotated, or the first sliding member 11 may be fixed and the second sliding member 12 may be rotated. Furthermore, in the above embodiment, the material supply port 14 is provided in the center of the second sliding member 12, but the material supply port 14 may be provided in the center of the first sliding member 11.

[0049] In addition, in the above embodiment, the case has been described in which the second sliding member 12 is cooled by a cooling medium, thereby indirectly cooling the first sliding member 11, but it is also possible to cool the first sliding member 11 by a cooling medium, thereby indirectly cooling the second sliding member 12, or to cool both the first sliding member 11 and the second sliding member 12 by a cooling medium. [Explanation of symbols]

[0050] 1...fine grinding device, 10...grinding section, 11...first mating member, 11A...guide area, 11B...first mating area, 12...second mating member, 12A...second mating area, 12B...insertion hole, 13...projection, 14...material supply port, 15...wing, 16...rotating shaft, 17...driving means, 18...cover body, 18A...through hole, 20...material supply means, 21...material fixed quantity supply machine, 2 2...material supply pipe, 30...recovery means, 31...temporary storage section, 32...guide pipe, 32A...upper guide pipe, 32B...lower guide pipe, 33...suction pipe, 34...sieve section, 35...ground material fixed quantity supply machine, 36...resupply pipe, 37...discharge section, 40...cooling means, 41...cooling device main body, 42...nozzle, 43...compressed air supply means, 44...piping, 45...refrigerant flow passage, 50...spraying means

Claims

1. A fine pulverizing apparatus for pulverizing waste materials containing resin, a crushing section that crushes a material by grinding a first grinding member and a second grinding member, the first grinding member and the second grinding member having a plurality of projections formed on at least a part of an opposing surface of the first grinding member and the second grinding member, A material supplying means for supplying material to the crushing section; A recovery means for recovering the pulverized material pulverized in the pulverizing section; A cooling means for cooling the grinding section; A fine pulverizing apparatus comprising:

2. The crushing unit is configured to rotate at least one of the first and second grinding members to grind their opposing surfaces together, and a material supply port connected to the material supply means is provided in the center of the first or second grinding member.

2. The fine pulverizing apparatus according to claim 1.

3. The fine grinding apparatus according to claim 1, characterized in that the first and second grinding members have a spacing between each protrusion in the range of 0.5 mm or more and 0.6 mm or less, an inner width of each protrusion in the range of 0.5 mm or more and 0.6 mm or less, an outer width of each protrusion in the range of 0.9 mm or more and 1.2 mm or less, and a height of each protrusion in the range of 0.8 mm or more and 0.9 mm or less.

4. 2. The fine grinding apparatus according to claim 1, wherein the cooling means comprises a cooling device main body which cools and discharges compressed air, a nozzle attached to the cooling device main body, a compressed air supply means which supplies compressed air to the cooling device main body, and a pipe which guides the compressed air from the compressed air supply means to the cooling device main body.

5. 2. The fine grinding apparatus according to claim 1, wherein said cooling means includes a refrigerant passage for circulating a cooling medium inside at least one of the first and second grinding members.

6. 2. The fine pulverizing apparatus according to claim 1, further comprising a spraying means for spraying water onto the material to be supplied to the pulverizing section.

7. 2. The fine pulverizing apparatus according to claim 1, wherein said recovery means comprises a sieve section for separating the pulverized materials according to size, and a re-supply pipe for returning the pulverized materials which did not pass through said sieve section to said pulverizing section.

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