JP3087201B2 - Jet mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a horizontal swirling type jet mill, in which a powder is pulverized by a high speed air jet, and a pulverizing zone and a classification zone are formed by a swirling flow.

[0002]

2. Description of the Related Art A jet mill of this type is used in a variety of fields such as heat-sensitive powder or ceramic powder, such as agricultural chemicals and toner, and crushes raw materials using high-speed air jets. is there. As is known from Japanese Patent Application Laid-Open No. 63-319067, the raw material is supplied to the inner peripheral portion of the pulverizing chamber, and compressed air is injected from a plurality of pulverizing nozzles provided on the side walls. In the pulverizing zone formed on the peripheral wall side of the pulverizing chamber by the swirling flow, the supplied pulverized raw material is accelerated and pulverized. The pulverized material is classified in a classification zone formed in the center of the pulverizing chamber and discharged from a discharge pipe in the center of the lower part of the pulverizing chamber. You.

Various improvements have been proposed for jet mills in order to increase the pulverization efficiency. In connection with the present invention, JP-A-4-210252 and JP-A-57-210252 have been proposed.
There is a technique disclosed in JP-A-84756. The former is
In the crushing chamber, by providing a spherical or cylindrical collision member facing the injection nozzle of the grinding nozzle, in addition to the collision of the grinding raw materials, the collision with the collision member is obtained to improve the grinding efficiency. I have. In the latter, while providing the collision member, an opening is provided in the peripheral wall surface of the crushing chamber, and this opening and the crushing nozzle are connected by a communication pipe, so that coarse powder in the crushing chamber is taken out from the opening and directly from the crushing nozzle. To collide with the collision member.

[0004]

In both of the above-mentioned improved technologies, although the crushing efficiency is excellent due to the use of the colliding action of the colliding member, the swirling flow formed by the crushing nozzle due to the presence of the colliding member. The normal flow of is greatly disrupted. Such turbulence in the swirling flow increases the pressure loss, decreases the speed of the swirling flow, and lowers the pulverizing ability. In addition, there is a problem that the classifying performance is immediately affected by the centrifugal force and the classifying performance is reduced, and the particle size distribution as product accuracy cannot be narrowed. Further, in the latter, a part of the swirling flow is bypassed through the communication pipe, so that the device becomes complicated.

The inventors of the present invention have conducted various studies to solve the above problems, and as a result, by devising the relative shape and arrangement of the collision members, it was possible to obtain excellent pulverizing ability and also improve the classifying function. It turned out that it can be done and led to the present invention. An object of the present invention is to provide a device without complicating the device configuration.
An object of the present invention is to provide a jet mill which can obtain a collision action of a collision member while improving classification performance, and can be adjusted immediately according to the properties and type of a pulverized raw material.

[0006]

That is, the present invention comprises a ring-shaped grinding chamber as a main component, a raw material supply means provided at an upper part of the grinding chamber and for introducing a raw material to the periphery of the chamber, and a lower part of the grinding chamber. A discharge pipe provided at a central portion for discharging pulverized and classified products; a plurality of pulverization nozzles provided at a side wall of the pulverization chamber for injecting compressed air into the chamber to form a swirling flow; In a jet mill having a collision member provided to face an injection port of a nozzle, the collision member has a width along a swirling flow direction formed to be 3 to 15 times a nozzle diameter of a pulverizing nozzle, and has a swirl shape. The lower end and the upper end along the flow direction are flat, flat collision plates formed into a blade-like shape, and the collision surface is in the flow direction of the swirling flow and forms an angle α of 30 with the center line of the opposing grinding nozzle. Incline in the range of ~ 60 degrees Characterized by providing fixed at an angle adjustable mounting means. In the above-described apparatus configuration, it is more preferable that one or more flat straightening plates are fixedly provided in the pulverizing chamber between the collision plates by an angle-adjustable mounting means.

[0007]

In the above apparatus of the present invention, a swirling flow is generated in the pulverizing chamber due to the high-speed air flow injected from the pulverizing nozzle. A zone is formed. The pulverized raw material supplied into the pulverizing chamber is sucked into the high-speed air flow jetted from the pulverizing nozzle, is subjected to a collision action by the flat collision plate, and moves toward the next pulverizing nozzle together with the swirling flow.
In this case, since the collision plate is provided opposite to the crushing nozzle at a predetermined large angle and at a predetermined inclination angle, the flow after the collision is regulated or controlled in the direction of the next crushing nozzle. At the same time, the pulverized fine powder is efficiently carried to the classification zone along with the swirling flow toward the center of the grinding chamber through the gap between the impingement plates, the gap between the impingement plate and the straightening plate, or the gap between the straightening plates. Then, while the fine powder having the product particle size is discharged toward the center from the discharge pipe to the outside, the coarse powder is blown toward the pulverizing zone by centrifugal force.

[0008]

1 and 2 schematically show a cross section and a vertical section of a main portion of a jet mill according to an embodiment of the present invention.
The jet mill 1 mainly includes an annular crushing chamber 2,
Raw material supply means 4 including a hopper 3 and the like, a discharge pipe 5 for discharging a product, and four crushing nozzles 6 for forming a swirling flow
And four collision plates 8 provided in the crushing chamber 2 via the mounting means 7, and a rectifying plate 9 provided between the collision plates 8 via the mounting means 7.

The crushing chamber 2 is formed by arranging an annular side wall 12 between a top plate 10 and a bottom plate 11. A suction nozzle 13 is installed on the top plate 10 at a predetermined position and at an angle.
The raw material inside is supplied. The bottom plate 11 is provided with a discharge pipe 5 at the center thereof so as to protrude into the room. The side wall 12 is located at a position dividing the periphery into four equal parts, and the crushing nozzles 6 are provided at an angle of 35 degrees from the diameter direction. Note that other known means can be applied to the basic configuration of such a jet mill 1.
For example, as in the case of a jet mill described in JP-A-63-319067, the material supply means 4 may be provided with a rotor with dispersing blades in the upper part of the pulverizing chamber 2 and supply the pulverized material on the rotor. As the pulverizing nozzle 6, an air supply chamber is provided on the outer periphery of the pulverization chamber 2, and compressed air can be injected from each nozzle through the air supply chamber.

The essential point of the present invention is that in the jet mill 1 as described above, a collision plate 8 is provided facing the crushing nozzle 6, and preferably a rectifying plate 9 is provided between the collision plates 8. Hereinafter, the configuration of the main part will be described in detail. In this embodiment, the collision plate 8 and the rectifying plate 9 have the same shape as shown in FIG.
(A) and (b) can be arbitrarily combined.

From various tests, it is assumed that the impingement plate 8 and the rectifying plate 9 are flat, and in addition, the width L along the swirling flow direction is 3 to 15 times the nozzle diameter of the crushing nozzle 6.
It is essential that the lower end and the upper end along the swirling flow direction are formed to be thin like a blade and have low fluid resistance. This requirement varies depending on the inclined state with respect to the pulverizing nozzle 6, the injection pressure, and the like, but is generally an allowable range for obtaining a predetermined collision action and minimizing the disturbance of the swirling flow. The height of the collision plate 8 and the current plate 9 is determined based on the top plate 10 or the bottom plate 1.
1, and more preferably, the gap between the top and bottom plates 10 and 11 is made as small as possible. As a specific shape, the collision plate 8 shown in FIG.
(Or a straightening plate 9), one surface of which is a flat surface 8a and the other surface is a single convex surface type of a convex surface 8b, and a double convex surface type in which both surfaces are convex such as a collision plate 14 (or a straightening plate) of FIG. 4
(B) a flat plate type with edges on both sides like the collision plate 15;
A crescent-shaped type such as a collision plate 16 (or a flow straightening plate) in FIG. If the collision plate has a flat surface, it is preferable to arrange the flat surface as the collision surface. In the case of the collision plate 15, both ends in the width direction (corresponding to the lower end and the upper end along the swirling flow direction) 15
It is preferable that a and 15b are thinly processed into an edge shape or an edge shape in order to maintain a normal swirling flow. When the thickness of a flat plate such as the collision plate 15 becomes extremely thin,
Since both side edges in the width direction have a blade shape as they are, such a case is also included in the collision plate of the present invention. In addition, such a collision plate and a current plate are usually made of stainless steel or carbon steel, but are not particularly limited as long as they are wear-resistant materials, and can be made of other alloys or ceramics. It is.

As shown in FIG. 6, the collision plate 8 and the rectifying plate 9 are installed so that their centers are located substantially on concentric circles in the crushing zone A. The distance between the tip of the crushing nozzle 6 and the collision plate 8, that is, the distance from the tip of the crushing nozzle 6 to the contact point between the crushing nozzle center line and the collision plate 8 is preferably in a range of 5 to 20 times the nozzle diameter. Outside, the grinding efficiency is reduced. Further, the collision plate 8 has a flat surface 8a which is the collision surface in the flow direction of the swirling flow, and
Is inclined in the range of 30 to 60 degrees and supported by the angle-adjustable mounting means 7. The rectifying plate 9 is provided in the middle of the adjacent collision plates 8, and its mounting angle, that is, the angle β between the crushing chamber diameter and the plane 9 a in the figure is inclined in the range of 60 to 120 degrees, It is supported by adjustable mounting means 7. Angle α = 30-60
Although the setting condition of the degree is slightly different depending on the injection pressure and the like from various tests, after the high-speed air flow injected from the pulverizing nozzle 6 hits the collision surface (the flat surface 8a), it is applied to the peripheral wall 2a of the pulverization chamber 2. As it moves, it is sucked between the next pulverizing nozzle 6 and the collision plate 8 so that the collision effect can be obtained again, and the classifying zone B is expanded together with the rectification operation of the rectifying plate 9 so that the classification operation can be favorably maintained. Turned out to be a range. Note that the collision plate or the current plate is
4 (b) and FIG. 4 (b), the installation inclination angles (angles α, β) are set at both ends in the width direction (lower end and upper end along the swirling flow direction). 1)
This is performed with reference to a virtual plane including 4a, 14b or 16a, 16b. In the case where the collision surface of the collision plate is a curved surface, the angle α uses a tangent line at the collision portion as a reference for its inclination.

The mounting means 7 includes a bolt 19 penetrating through the bottom plate 11 as shown in an enlarged view in FIG.
It consists of a support rod 20 connected to the upper part, a nut 21 screwed into the outer protrusion of the bolt 19 and tightened. The collision plate 8 or the rectifying plate 9 is fixed to the support rod 20, and the nut 21 is loosened to adjust the angle. I do. It is sufficient that such a mounting means 7 can adjustably fix a flat plate-shaped member such as the collision plate 8 and the rectifying plate 9 at a predetermined inclination angle, and can finely adjust it more easily by using gears, screws, link mechanisms and the like. It is also possible to do so.

Next, using the above jet mill 1,
Tables 1 and 2 show examples of test results when the effects of the present invention were examined.

[0015]

[Table 1]

[0016]

[Table 2]

(1) Calcium carbonate (average particle size d50 = 115 μm) and electrophotographic toner (average particle size d50 = 250 μm) were used as grinding raw materials. (2) The main dimensions and operating conditions are as follows.・ Inner diameter of crushing chamber 2 = 300 mm, inner wall height of crushing chamber 2 =
70 mm-The same shape of the collision plate and the current plate was used. As an example of the present invention, a uniconvex surface type shown in FIG.
0 mm and a maximum thickness of 5 mm. 4) and a flat type with both edges (width L is 30 mm and thickness is 2 mm, hereinafter abbreviated as a flat plate). It should be noted that the one-sided convexity means only the case where the arrangement of the collision plate and the rectifying plate is the same as that in FIG. Comparative examples are a cylinder having a diameter of 25 mm as a collision member, a sphere having a diameter of 25 mm, and a case without a collision plate. -The mounting angle α of the collision plate was inclined at 45 degrees. The mounting angle β of the current plate is the inclination angle shown in parentheses next to the current plate in each table. The flow rate of the compressed air of the crushing nozzle 6 is 1.8 to 1.9 nm ³ / mi for the toner for electrophotography.
n In the case of calcium carbonate, 2.7 nm ³ / min. The pulverization pressure was 5.5 kg / cm ^{2 in} the case of the toner for electrophotography, and the pulverization test was performed under the condition of 6.3 kg / cm ² or more in the case of calcium carbonate. (3) The pulverization result is volume average particle size μm for each product.
(D ₅₀ ), and 90
Calculated for% pass diameter ÷ 10% pass diameter (d ₉₀ / d _10).

From Tables 1 and 2, the following becomes clear. First, in both cases of calcium carbonate and toner, the pulverizing ability is greatly influenced by the shape of the collision member as well as the presence or absence of the collision plate, and the structure of the present invention is the most excellent. Also, the pulverization results vary greatly depending on whether or not to provide a current plate in addition to the collision plate, for example,
In Table 2, at the value of d ₉₀ / d ₁₀ , NO2 is 4.5 for NO1 and 4.5 for NO3, and NO4 is 5.3 for NO3 and 5.3 for NO3. Better particle size distribution. Further, in the present invention, for example, as can be seen from the comparison between NO2 and NO4 in Table 2 or the comparison between NO1 and NO3 in Table 2, the one-side convex type is superior to the flat type with both side edges. The effect is obtained.

[0019]

As described above, in the jet mill according to the present invention, the shape, size and arrangement of the flat impingement plate are devised. , A high pulverization efficiency is achieved, and a pulverized product having a narrow particle size distribution can be obtained. Further, since the apparatus configuration is simple, it is excellent in cost. In addition, since the flat collision plate and the straightening plate are fixed by the angle-adjustable mounting means, for example,
It can be adjusted to the optimum condition depending on the properties of the raw material.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the configuration of a jet mill according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the jet mill configuration.

FIG. 3 is a perspective view showing an example of the shape of a collision plate or a flow straightening plate of the present invention.

FIG. 4 is a perspective view showing another example of the shape of a collision plate or a current plate in the present invention.

FIG. 5 is a cross-sectional view of a main part showing attachment means for the collision plate and the current plate.

FIG. 6 is a schematic diagram showing an arrangement state of a collision plate and a current plate.

[Explanation of symbols]

 1 is a jet mill. 2 is a grinding chamber. 4 is a raw material supply means. 5 is a discharge pipe. 6 is a pulverizing nozzle. Reference numeral 7 denotes a mounting means. 8 is a collision plate. 9 is a current plate. Reference numerals 14, 15, and 16 denote collision plates or flow regulating plates.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-80588 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B02C 19/00 B02C 19/06

Claims (2)

(57) [Claims] A material supply means mainly provided with an annular crushing chamber and provided at an upper portion of the crushing chamber for introducing a crushed material to a peripheral portion of the chamber, and a crushing and classification provided at a lower central portion of the crushing chamber. A discharge pipe for discharging the product, a plurality of pulverization nozzles provided on the side wall of the pulverization chamber and injecting compressed air into the chamber to form a swirling flow, and provided in opposition to the injection ports of the pulverization nozzles. The collision member has a width along the swirling flow direction formed to be 3 to 15 times the nozzle diameter of the pulverizing nozzle, and has a lower end and an upper side along the swirling flow direction. The end surface is a flat collision plate having a thin blade-like shape, and its collision surface is in the flow direction of the swirling flow, and the angle α that forms the center line of the opposed crushing nozzle is 30 to
A jet mill, wherein the jet mill is tilted in a range of 60 degrees and fixed by mounting means capable of adjusting an angle. 2. In the crushing chamber, one crushing plate is provided between each collision plate.
The jet mill according to claim 1, wherein at least one flat straightening plate is fixedly provided by an angle-adjustable mounting means.