JP2013039508A - Medium stirring type crusher - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medium stirring type crusher capable of performing stable crushing treatment to obtain slurry with nano-sized particles dispersed therein without causing the flocculation of solid particles.SOLUTION: The medium stirring type crusher includes a crushing rotor 40 rotated around the axis of a container 20 to stir a treated material and a medium 70; a separating rotor 50 rotated around the axis to centrifugally separate the medium from the treated material; and a hollow rotating shaft 30 rotating the separating rotor 50 and forming a discharge passage 31 of the treated material after separated. The crushing rotor 40 includes a cylindrical part 42 with a plurality of blades arranged in cylindrical shape around the axis, and the total of the cross-sectional areas of the blades is not more than 50% of the area of a ring-like locus drawn by the rotation of the blades in a cross section orthogonal to the axis.

Description

  The present invention relates to a media agitation type pulverizer, and more particularly, to a media agitation type pulverizer that can obtain a slurry in which nano-sized fine particles are dispersed by continuously supplying a slurry-like processed product and agitation with the medium.

  The pulverization treatment for obtaining a dispersion liquid composed of nano-sized fine particles is performed in a very wide field such as inks, paints, toners, color resists, ceramics, metal oxides, metals and pharmaceuticals. The nano-sized fine particles have a property that the particles are aggregated and become larger, and the primary particles may aggregate to form secondary particles, and the secondary particles may aggregate to form tertiary particles. Therefore, the pulverization process for obtaining nano-sized fine particles includes a process of crushing secondary particles to primary particles and a process of crushing tertiary particles to secondary particles.

  One of the pulverizers used for these treatments is a wet media stirring pulverizer. In this pulverizer, a slurry-like processed product is agitated with a medium, whereby solid particles are pulverized by a shearing force or an impact force between the media and dispersed in the processed product. Patent Document 1 describes a media agitation type pulverizer that can use a medium having a particle diameter of 0.1 mm or less and thereby can obtain a dispersion having an average particle diameter of 100 nm or less. . The structure of this pulverizer is shown in FIGS.

  This media agitation type pulverizer 110 includes a processing product supply port 121 provided on one side wall 126 of a cylindrical container 120 containing a medium 170, and a discharge passage 131 provided on a hollow rotating shaft 130. The slurry-like processed product can be continuously processed in the internal pulverization chamber. In the container 120, a crushing rotor 140 for stirring the processed material and the medium 170 and a separation rotor 150 for separating the processed material and the medium 170 are attached to the rotating shaft 130. As the rotating shaft 130 rotates, the grinding rotor 140 and the separation rotor 150 rotate.

  The crushing rotor 140 includes a disc-shaped holding portion 141 fixed to the rotating shaft 130 and a cylindrical portion 142 in which a plurality of blades 145 are arranged in a cylindrical shape around the axis. The processed material and the medium 170 are agitated by the rotation of the blade 145, and at this time, the solid particles in the processed material can be pulverized by the shearing force or the impact force generated between the media 170.

  The separation rotor 150 includes a disk-shaped holding portion 151 that is positioned inside the grinding rotor 140 and is fixed to the rotating shaft 130, and a plurality of blades 155 that are arranged in a cylindrical shape around the axis. The plurality of blades 155 are closed on one side by the holding portion 141 of the grinding rotor 140 and closed on the other side by the holding portion 151.

  The processed material introduced into the pulverization chamber from the supply port 121 is subjected to the pulverization process, passes through the openings 156 between the blades 155, and is discharged from the discharge path 131 of the rotary shaft 130 to the outside. At this time, due to the rotation of the blade 155, a centrifugal force acts on the solid particles and the medium 170 in the processed material. And since the particle size of the media 170 is larger than the particle size of the solid particles in the processed material, a large centrifugal force will work and it will not flow toward the center and will be separated from the processed material. become.

  In this way, the processed product and the medium 170 can be separated by the rotation of the separation rotor 150, and at the same time, the solid particles in the processed product can be sorted and classified. In this example, the rotating shaft 130 is formed to rotate the separation rotor 150 and the grinding rotor 140. However, the separation rotor 150 and the crushing rotor 140 can also be rotated by different rotating shafts, and Patent Literature 2 describes a media agitation type crusher having two rotating shafts.

  The media agitation type pulverizer 110 can continuously pulverize the slurry-like processed product. And since it is possible to use the medium 170 with a particle diameter of 0.1 mm or less, a slurry in which fine particles of 100 nm or less are dispersed can be obtained. Here, the separation rotor 150 has an excellent separation performance by centrifugation, and can discharge only the processed material without mixing the medium 170 into the processed material.

  However, in the pulverization process using the media agitation pulverizer 110, the slurry-like processed product may generate an abnormally large amount of heat. Further, scratches (chipping) may occur on the surface of the solid particles due to the pulverization treatment. Furthermore, the solid particles may aggregate and the average particle size may increase.

JP 2006-247557 A JP 2006-212488 A

  An object of the present invention relates to a media agitation type pulverizer capable of obtaining a slurry composed of nano-sized fine particles by continuously stirring a slurry-like processed product together with a medium, and to obtain a target fine particle slurry. Another object is to provide a media stirring type pulverizer capable of performing a soft pulverization process. In addition, the slurry-like processed product does not cause abnormal heat generation, can be stably pulverized, does not cause scratches (chipping) on the surface of the solid particles, and the solid particles may agglomerate. There is no media stirring type crusher.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that, in the conventional media agitation type pulverizer, partial deviation or stagnation occurs in the flow of the media. As a result, it was found that the shearing force becomes abnormally strong and the above problem occurs. As a result of repeated trials and errors to improve the grinding rotor, we succeeded in forming a uniform and stable media circulation flow by eliminating media bias and stagnation as much as possible. The invention has been completed.

  A media agitation type pulverizer according to claim 1 of the present invention continuously supplies a slurry-like processed product into a cylindrical container containing a pulverizing medium, and agitates the processed product together with the media. A medium agitation type pulverizer for pulverizing solid particles in the processed product, wherein the pulverizing rotor rotates about the axis of the container and agitates the processed product and the media; and inside the pulverizing rotor And a separation rotor that rotates about the axis and centrifuges the processed material and the medium, and a rotating shaft that rotates the separation rotor forms a hollow shape so that the processed material after separation A discharge path is formed, and the grinding rotor includes a disk-shaped holding portion and a cylindrical portion in which a plurality of blades are arranged in a cylindrical shape, and has a cross-sectional area of the blade in a cross section perpendicular to the axis. The sum is It employs the means is 50% or less of the area of the ring-shaped locus drawn by the rotation of the serial blades.

  A media agitation type pulverizer according to claim 2 of the present invention is the media agitation type pulverizer according to claim 1, wherein the outer periphery of the blade is the same as the outer periphery of the ring-shaped locus in the cross section. It is provided with a curvature, and a means is adopted in which the total outer peripheral length of the blade is 50% or less of the outer peripheral length of the ring-shaped locus. Further, a media agitation type pulverizer according to claim 3 of the present invention is the media agitation type pulverizer according to claim 1, wherein the blade has a circular cross section in the cross section. . A media agitation type pulverizer according to claim 4 of the present invention is the media agitation type pulverizer according to any one of claims 1 to 3, wherein the pulverization rotor is one of the cylindrical portions. The side of the blade is closed by the holding portion and the other side is opened, and the end of the other side employs means in which the end of each blade is connected by an end ring. Furthermore, the media agitation type pulverizer according to claim 5 of the present invention is the media agitation type pulverizer according to any one of claims 1 to 4, wherein the hollow rotating shaft is the separation rotor. And means for rotating the grinding rotor.

  The media agitation type pulverizer of the present invention can be made into a slurry in which target nano-sized fine particles are dispersed by performing a soft and stable pulverization treatment. The slurry-like processed product does not cause abnormal heat generation, and stable pulverization is possible. The surface of the solid particles is not scratched (chipped), and the solid particles are aggregated during the processing. There is no waking.

It is a schematic sectional drawing which shows the media stirring type crusher concerning the Example of this invention. It is a schematic sectional drawing by the AA arrow of FIG. The grinding | pulverization rotor of the media stirring type grinder shown in FIG. 1 is shown, (a) is a schematic perspective view, (b) is a schematic sectional drawing by the BB arrow of (a). The example of another grinding | pulverization rotor is shown, (a) is a schematic perspective view, (b) is a schematic sectional drawing by CC arrow of (a). It is a flowchart which shows the processing apparatus used for the test. It is a graph which shows a test result and represents the average particle diameter with respect to processing time. It is a graph which shows a test result and represents the zeta potential with respect to an average particle diameter. It is a schematic sectional drawing which shows the conventional media stirring type grinder. It is a schematic sectional drawing by DD arrow of FIG. FIG. 9 shows a crushing rotor of the media agitating crusher shown in FIG. 8, (a) is a schematic perspective view, and (b) is a schematic cross-sectional view taken along line EE in (a).

Hereinafter, embodiments of the present invention shown in the drawings will be described.
FIG. 1 is a schematic cross-sectional view of the media stirring type pulverizer of the present invention, and FIG. 2 is a schematic cross-sectional view taken along the line AA in FIG. FIG. 3 shows the grinding rotor, (a) is a schematic perspective view, and (b) is a schematic cross-sectional view orthogonal to the axis in the direction of arrows BB in (a). The media agitation type pulverizer 10 includes a container 20, a rotating shaft 30, a pulverizing rotor 40, a separation rotor 50, and the like.

  The container 20 has a cylindrical shape and forms a crushing chamber therein. The pulverization chamber preferably has the slurry-like processed product flowing in a completely mixed state, and is formed with rounded corners in order to improve the fluidity of the processed product. The axial length (L) is smaller than the inner diameter (D), that is, L / D is smaller than 1. The processed product is introduced into the pulverization chamber from a supply port 21 provided on one side wall 26 of the container 20. And it discharges | emits from the discharge path 31 formed in the rotating shaft 30 provided by penetrating the same side wall 26. FIG.

  In addition, the container 20 is divided into two parts by a plane perpendicular to the axis, and is integrally assembled by flanges 23 and 24. In addition, the container 20 includes a jacket 60 on the outside and a water supply port 61 and a drain port 62 so that cooling water or the like can be supplied to the inside. In general, since the pulverization process generates heat, the processed product often needs to be cooled. In FIG. 1, the container 20 is described as a vertical container having a vertical axis. However, in the present invention, a horizontal container having a horizontal axis can also be used.

  The rotating shaft 30 has a hollow shape, and has the same axis as the container 20, and is rotatably provided through one side wall 26 of the container 20. A shaft seal 34 is interposed between the rotary shaft 30 and the side wall 26 in a portion where the rotary shaft 30 is inserted, so that the inside of the container 20 can be sealed. The crushing rotor 40 and the separation rotor 50 fixed to the rotating shaft 30 rotate integrally with the rotating shaft 30 around the axis of the container 20. The crushing rotor 40 and the separation rotor 50 do not necessarily have to be fixed to the same rotating shaft 30, and can be made to be separate rotating shafts and rotate at different rotational speeds.

  The crushing rotor 40 includes a disc-shaped holding portion 41 fixed to the rotary shaft 30 and a cylindrical portion 42 in which a plurality of blades 45 are arranged in a cylindrical shape around the axis. The cylindrical portion 42 is formed such that a plurality of openings 46 are cut out from a cylindrical material at regular intervals in the circumferential direction, and a blade 45 is formed between the two openings 46. One side of the cylindrical part 42 is closed by the holding part 41, and the other side is open. The open end of the other side preferably has a structure in which the end of each blade 45 is connected by an end ring 43.

  When the crushing rotor 40 rotates in the crushing chamber, the processed material and the medium 70 rotate in the rotation direction of the crushing rotor 40. Then, due to the centrifugal force generated by the rotation, the processed material and the medium 70 flow through the openings 46 from the inside toward the outside. As a result, the processed material and the medium 70 form a circulation flow x that circulates inside and outside the grinding rotor 40 as indicated by arrows in FIG. That is, it flows from the inside to the outside in the opening 46, flows from one side wall 26 to the other side wall 27 outside the cylindrical portion 42, and flows from the outside to the inside near the side wall 27. Inside the portion 42, the fluid flows from the other side wall 27 toward the holding portion 41. When the cylindrical part 42 is provided with the end ring 43 at the open end, a circulation flow x is formed around the end ring 43, and a very good flow state is formed. be able to.

  By forming a circulation flow x that circulates inside and outside the grinding rotor 40, the grinding chamber becomes completely mixed, and the grinding process is performed in the completely mixed state. Then, the medium 70 and the slurry-like processed product stably flow, so that a uniform shearing force or impact force can be generated between the media 70 and the pulverization process can be performed in a soft state. In addition, this invention is provided with the characteristic in the grinding | pulverization rotor 40, and a detailed structure and a function are mentioned later.

  The separation rotor 50 includes a disk-shaped holding portion 51 that is positioned inside the grinding rotor 40 and is fixed to the rotary shaft 30, and a plurality of blades 55 that are arranged in a cylindrical shape around the axis. The plurality of blades 55 have a plate shape and are sandwiched between the holding portion 41 of the grinding rotor 40 and the holding portion 51 of the separation rotor 50. That is, one side of the separation rotor 50 is closed by the holding portion 41, and the other side is closed by the holding portion 51. An opening 56 is formed between the blades 55.

  A gap is formed between the inner peripheral surface of the blade 45 of the grinding rotor 40 and the outer peripheral surface of the blade 55 of the separation rotor 50, and this space 47 forms a part of the flow path of the circulation flow x described above. Yes. Further, a gap is also formed between the inner peripheral surface of the blade 55 of the separation rotor 50 and the outer peripheral surface of the rotary shaft 30, and a space 57 is formed. That is, the space 47 outside the separation rotor 50 and the space 57 inside the separation rotor 50 communicate with each other through the opening 56 between the blades 55.

  The space 57 inside the separation rotor 50 communicates with the discharge path 31 formed in the hollow portion of the rotation shaft 30 through the opening 32 provided in the rotation shaft 30. As a result, the processed material introduced into the pulverization chamber from the supply port 21 is stirred together with the medium 70 to form a circulation flow x, and after being subjected to the pulverization process, the opening 56 between the blades 55 and the space inside the blade 55. 57, and discharged from the discharge path 31 to the outside through the opening 32.

  Naturally, such a path of the processed material also becomes a flow path for the medium 70, but both are separated by the centrifugal separation function of the separation rotor 50. That is, the processed material and medium 70 to be flowed are subjected to centrifugal force due to the rotation of the separation rotor 50 at the openings 56 between the blades 55. As a result, the solid particles having a small particle diameter can flow toward the space 57, but the solid particles having a large particle diameter and the medium 70 are returned to the space 47 by centrifugal force.

  In this way, the separation rotor 50 can separate the solid particles in the processed material from the medium 70. In addition, small solid particles and large solid particles can be classified. As a result, only the slurry-like processed product in which small solid particles are dispersed is discharged from the discharge path 31.

  The features of the grinding rotor 40 of the present invention will be described with reference to FIG. The grinding rotor 40 of the present invention includes a cylindrical portion 42 in which a plurality of blades 45 are arranged in a cylindrical shape around an axis. Here, as shown in FIG. 3B, the total sum of the cross-sectional areas (shaded portions) of the blade 45 is considered when viewed in a cross section orthogonal to the axis. Further, considering the locus drawn by the blade 45 when the blade 45 rotates, as shown in FIG. 3B, it is a ring-like locus formed by the outer circle m and the inner circle n. I understand that.

  The present invention is characterized in that the total cross-sectional area of the blade 45 is 50% or less of the area of the ring-shaped locus. More specifically, by setting the total cross-sectional area of the blade 45 to 20% to 40% of the area of the ring-shaped locus, a good flow state can be obtained.

  Further, the grinding rotor 40 is formed so that the outer periphery of the blade 45 overlaps the outer peripheral circle of the ring-shaped locus. That is, the curve on the outer periphery of the blade 45 has the same curvature as the outer periphery of the ring-shaped locus. Here, the sum of the lengths of the curves on the outer periphery of the blade 45 is compared with the length of the outer periphery of the ring-shaped locus.

  In the present invention, when the outer periphery of the blade 45 has the same curvature as the outer periphery of the ring-shaped locus, the total length of the outer periphery of the blade 45 is 50% or less of the length of the outer periphery of the ring-shaped locus. It is characterized by that. More specifically, an even better flow state can be obtained by setting the total length of the outer circumference of the blade 45 to 20% to 40% of the length of the outer circumference of the ring-shaped locus.

  FIG. 4 shows another example of a grinding rotor used in the present invention. That is, the grinding rotor 40a is similar to the grinding rotor 40 of FIG. 3, but the blade 45 has a circular cross section. The grinding rotor 40a satisfies the condition that the sum of the cross-sectional areas of the blades 45 is 50% or less of the area of the ring-shaped locus. However, the outer periphery of the blade 45 has a different curvature from the outer periphery of the ring-shaped locus.

  Next, for the conventional grinding rotor 140 shown in FIG. 10, the above conditions are compared with the present invention. The grinding rotor 140 includes a cylindrical portion 142 in which a plurality of blades 145 are arranged in a cylindrical shape around an axis. Here, as shown in FIG. 10B, the total sum of the cross-sectional areas (shaded portions) of the blade 145 is considered when viewed in a cross section orthogonal to the axis. Further, considering the trajectory drawn by the blade 145 when the blade 145 rotates, as shown in FIG. 10B, it is a ring-shaped trajectory formed by the outer circle m and the inner circle n. I understand that.

  In the grinding rotor 140, the sum of the cross-sectional areas of the blades 145 exceeds 50% of the area of the ring-shaped locus. Therefore, the media agitation type pulverizer 110 is not included in the present invention.

  Further, the grinding rotor 140 is formed such that the outer periphery of the blade 145 overlaps the outer peripheral circle of the ring-shaped locus. That is, the curve on the outer periphery of the blade 145 has the same curvature as the outer periphery of the ring-shaped locus. However, the total length of the curved lines on the outer periphery of the blade 145 exceeds 50% of the outer peripheral length of the ring-shaped locus. Therefore, also in this point, the media agitation type pulverizer 110 is different from the present invention.

  As described above, the media agitation type pulverizer 10 of the present invention is characterized by the structure of the pulverization rotor 40, and has a smaller cross-sectional area of the blade 45 than the conventional pulverization rotor 140, and the opening 46. The area is increased. In addition, when the curve of the outer periphery of the blade 45 has the same curvature as the outer periphery of the ring-shaped locus, the length of the curve of the outer periphery of the blade 45 is shortened compared to the conventional grinding rotor 140, The area of the outer peripheral surface of the blade 45 is reduced.

  Next, the grinding rotor 40 of the present invention and the conventional grinding rotor 140 will be compared in terms of functions and effects. In the conventional grinding rotor 140, since the area of the outer peripheral surface is increased, it can be considered that the shearing force generated between the outer peripheral surface and the peripheral wall 125 of the container 120 is very large. And it was thought that increasing the shearing force would increase the efficiency of the grinding treatment.

  And even when the above problems occurred, these problems were not considered to be due to a large shear force. In particular, as a result of increasing the pulverization efficiency, solid particles agglomerate in the pulverization process, and as a result, increasing the average particle diameter of the processed product is a problem that is difficult to understand. Accordingly, trial manufactures were made of variously-structured grinding rotors, and the grinding treatment test was repeated by trial and error.

  As a result, in the conventional media agitation type pulverizer 110, it was found that the shearing force between the outer peripheral surface of the pulverization rotor 140 and the peripheral wall 125 was too strong depending on the processed material. Further, in the grinding rotor 140, since the area of the opening 146 is narrower than the area of the outer peripheral surface of the blade 145, the circulation flow does not become a smooth flow, and media bias and stagnation occur. As a result, it was found that the shear force partially increased. In order to solve the above problems, it has become clear that it is effective to reduce the outer peripheral area of the blade 145 and increase the area of the opening 146. As a result, a smooth circulating flow is formed, the shearing force is reduced, and a uniform and stable circulating flow can be obtained. Therefore, the occurrence of media bias and stagnation is eliminated, and the problem that a partly abnormally strong shearing force is generated can be solved.

  As described above in detail, in the media agitation type pulverizer 10 of the present invention, the structure of the pulverization rotor 40 is determined by the relationship between the cross-sectional area of the blade 45 and the area of the ring-shaped locus drawn by the rotation of the blade 45. Therefore, it is possible to eliminate the unevenness and stagnation of the media and to obtain a uniform and stable circulation flow. A uniform and stable circulating flow generates a uniform and stable shearing force, and a soft grinding process can be performed by the moderated shearing force.

  As a result, the media agitation type pulverizer 10 of the present invention has a problem that the conventional media agitation type pulverizer 110 has a problem. It can be performed. Further, the surface of the solid particles is not scratched (chipped) by the pulverization process, and the solid particles are not aggregated.

  Using the pulverization processing system shown in FIG. 5, the pulverization performance of the media agitation pulverizer 110 using the conventional pulverization rotor 140 and the media agitation pulverizer 10 using the pulverization rotor 40 of the present invention are compared. A test was conducted. Here, the difference between the two is only the grinding rotor, and all other configurations are the same. This pulverization processing system includes a media agitation pulverizer 10 (110), a processing product holding tank 81, a circulation pump 82, and a circulation line 83 connecting them.

  The slurry-like processed material put into the holding tank 81 is supplied to the media agitation type pulverizer 10 (110) by the circulation pump 82, and after being subjected to the pulverization process, returns to the holding tank 81 again. Yes. Therefore, the processed product is repeatedly subjected to a pulverization process by the media agitating pulverizer 10 (110). And the grinding | pulverization process advances about the whole processed material in a system, and refinement | miniaturization of a solid particle progresses gradually.

  The treated product was obtained by mixing organic pigment powder (quinacridone-based magenta pigment) and a solvent (toluene) into a slurry, and the pigment concentration was 10% by mass. The media agitation type pulverizer 10 of the present invention and the conventional media agitation type pulverizer 110 were replaced and tested. However, other processing items, processing systems, and operating conditions of the media agitation type pulverizer (rotation speed, circulation flow rate, etc.) The amount charged to the holding tank 81 was all the same.

  FIG. 6 shows the change in the particle diameter of the pigment with respect to the processing time. Here, the particle size is indicated by a cumulative 50% (d50) in the particle size distribution. When the conventional pulverizing rotor 140 is used, the particle diameter becomes small immediately after the start of the treatment, but after 15 minutes, the particle diameter becomes large, indicating that the pigment particles are aggregated. On the other hand, when the grinding rotor 40 of the present invention is used, it shows that stable grinding processing was performed without causing aggregation.

  FIG. 7 shows the relationship between the pigment particle diameter and the zeta potential. The curve of the graph is a curve calculated from measured values by the least square method. The zeta potential indicates that the dispersion stability of the solid particles is higher as the absolute value is larger when the slurry having the same average particle diameter is compared. When dispersed by excessive force, the primary particles are easily damaged, and thus the dispersed state becomes unstable and the absolute value of the zeta potential becomes small. On the other hand, when dispersed by a soft and uniform force, the primary particles are not easily damaged, the dispersion state is stabilized, and the absolute value of the zeta potential is increased. The graph in FIG. 7 indicates that the particle size is smaller as it is located on the left side, and the stability is higher as it is located on the upper side. Therefore, the closer to the upper left, the smaller the average particle size and the more stable the dispersion.

  FIG. 7 shows that the treatment with the media agitation pulverizer 10 of the present invention is superior in dispersion stability than the treatment with the conventional media agitation pulverizer 110, and a preferable dispersion can be obtained. Is shown.

  The crushing rotor 40 and the separation rotor 50 do not necessarily have to be fixed to the same rotating shaft 30, and can be made to be separate rotating shafts and rotate at different rotational speeds. In this case, if attention is paid to the structure in which the blade 55 of the separation rotor 50 is sandwiched between the pair of holding portions 51, it can be easily implemented with reference to the cited document 2 and the like.

DESCRIPTION OF SYMBOLS 10 Media stirring type grinder 20 Container 30 Rotating shaft 31 Discharge path 40 Grinding rotor 41 Holding part 42 Cylindrical part 43 End ring 45 Blade 50 Separation rotor 70 Media

Claims (5)

Media stirring type pulverization in which a slurry-like processed product is continuously supplied into a cylindrical container containing a pulverizing medium, and the processed product is stirred together with the media to pulverize solid particles in the processed product. Machine,
A crushing rotor that rotates about the axis of the vessel and stirs the processed material and the media;
A separation rotor that is located inside the grinding rotor and rotates about the axis to centrifuge the processed material and the media;
A rotating shaft for rotating the separation rotor has a hollow shape, and forms a discharge path for the processed material after separation,
The crushing rotor includes a disk-shaped holding portion and a cylindrical portion in which a plurality of blades are arranged in a cylindrical shape, and a total cross-sectional area of the blades in a cross section perpendicular to the axis is A media agitation type pulverizer characterized in that it is 50% or less of the area of a ring-shaped locus drawn by rotation.   The outer periphery of the blade has the same curvature as the outer periphery of the ring-shaped locus in the cross section, and the total length of the outer periphery of the blade is 50% or less of the length of the outer periphery of the ring-shaped locus. The media agitation type pulverizer according to claim 1.   The media stirring type pulverizer according to claim 1, wherein a cross section of the blade in the cross section is circular.   The grinding rotor has a structure in which one side of the cylindrical part is closed by the holding part and the other side is opened, and the end part of the other side is connected to the end part of each blade by an end part ring. The media agitation type pulverizer according to any one of claims 1 to 3, wherein the media agitation type pulverizer is used. The media stirring type pulverizer according to any one of claims 1 to 4, wherein the hollow rotating shaft rotates the separation rotor and the pulverization rotor.