JPH03213161A - Pulverizing apparatus - Google Patents

Abstract

PURPOSE:To enhance grinding energy efficiency and to prepare a ground product having narrow grinding particle size distribution by providing impact members corresponding to respective grinding nozzles in front of the grinding direction of the respective grinding nozzles so that jet air collides with the impact members. CONSTITUTION:A rotary classifier 8 is mounted to the upper part of a grinding chamber 6 and compressed air is injected from a plurality of grinding nozzles 3 within the grinding chamber 6 to grind the solid introduced into the grinding chamber 6 by a screw conveyor A. Impact members 2 are provided in front of the jet direction of the respective grinding nozzles 3 corresponding to the grinding nozzles 3 so that jet air collides with the impact members 3. As a result, two forces due to the collision between particles and the collision of particles with the impact members are effectively utilized and grinding energy efficiency becomes high and a ground product having narrow grinding particle size distribution can be prepared.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of a fluidized bed jet mill equipped with a rotary classifier, and in particular to a pulverization device that improves the energy consumption during pulverization and the pulverized particle size distribution. .

(Prior art) Generally, a fluidized bed jet mill equipped with a rotary classifier (
(hereinafter simply referred to as a fluidized bed jet mill), compressed air is injected from a crushing nozzle, and the energy of the high-speed air flow causes particles to collide with each other, crushing solids, and then centrifuging the particles using a rotary classifier. The particles are classified to obtain particles having the desired pulverized particle size.

The advantage of a fluidized bed jet mill is that it uses compressed air injection, which lowers the temperature due to adiabatic expansion.
It is also possible to crush heat-sensitive solids, and by having an internal classifier, the number of equipment can be reduced compared to the normal closed circuit system (system with an external classifier), and product changeability is improved. It has the advantage of being excellent in cleanability, leading to cost reduction, and being suitable for fine pulverization because particles collide with each other, that is, surface pulverization is mainly performed.

(Problems to be Solved by the Invention) By the way, in the fluidized bed jet mill as described above, a large compressor is required because a large amount of compressed air is used, and the energy consumption for grinding is 2 to 2 times lower than that of a mechanical mill. Because it is extremely large (5 times as large) and mainly collides with each other, it is easy to generate ultra-fine powder, and particles that have fewer collisions are discharged as coarse powder, resulting in a wider pulverized particle size distribution. There was a problem.

In addition, in order to increase the crushing effect, a fluidized bed jet mill has been proposed in which a center core is provided as a collision member at the center of three crushing nozzles (see 63-21672).
In this fluidized bed jet mill, the three jet airs cross-collided and interfered with each other, making it impossible to expect a significant improvement in grinding efficiency.

The present invention has been made in view of the above-mentioned circumstances, with the purpose of improving the above-mentioned drawbacks in the conventional technology.

That is, an object of the present invention is to install a collision member in front of a crushing nozzle in the jetting direction, effectively utilize the two forces of collision between particles and collision of particles with the collision member, and achieve high crushing energy efficiency. Another object of the present invention is to provide a pulverizing device that produces a pulverized product having a narrow pulverized particle size distribution.

(Means for Solving the Problems) The present invention comprises a fluidized bed jet mill that is equipped with a rotary classifier above the grinding chamber and injects compressed air from a plurality of grinding nozzles in the grinding chamber to grind solid matter. The pulverizing device is characterized in that a collision member is provided in front of each pulverizing nozzle in the injection direction so as to correspond to each pulverizing nozzle so that the injected air collides with the pulverizing nozzle.

The pulverizing apparatus of the present invention will be described with reference to drawings corresponding to embodiments. It consists of a type jet mill, a disk-shaped classification rotor 8 on top of the jet mill, and a rotation drive device 9 for rotating the classification rotor. A collision member 2 is provided in front of each crushing nozzle 3 in the injection direction, so that the air jetted from the crushing nozzle collides with the collision member 2.

In the present invention, the installation position of the collision member is such that when the center direction of the jet air from the crushing nozzle is O'', the center of the collision surface of the collision member is within a conical range having an apex angle of 20'' or less. It is preferable that the distance between the tip of the collision surface of the collision member and the tip of the crushing nozzle is 5 times or less than the potential core zone.

The impingement member may be made of alloy, surface-treated metal, or ceramic and may have a spherical, oval, cylindrical, or dome shape, and may be sized to accommodate the center of the jet of air. The area of the plane or cross section perpendicular to the direction is 50% of the cross-sectional area of the minimum inner diameter of the crushing nozzle.
It is preferable that the amount is less than twice that.

(Function) In the pulverizing device of the present invention, the compressed air injected from the plurality of pulverizing nozzles collides with the collision member provided forward in the compressed air injection direction, so that the compressed air energy that is not used and is consumed is saved. It can be effectively used for crushing. Further, the collision between the particles and the collision member increases the volumetric pulverization effect, and a pulverized product with a small amount of fine powder and a sharp particle size distribution can be obtained.

(Example) Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of the pulverizing device of the present invention, and FIG. 2 is a longitudinal sectional view of the pulverizing device of the present invention.

In the figure, 1 is the main body of a fluidized bed jet mill, 2 is a collision member,
3 is a crushing nozzle, 4 is a compressed air chamber, 5 is a discharge pipe, B is a crushing chamber, 7 is a collision member support part, 8 is a classification rotor, 9 is a rotary drive device, 0 is a coarse powder intrusion prevention ring, 11 is a This is a raw material supply device.

In the above-mentioned pulverizing apparatus, the pulverized raw material is introduced into the lower part of the pulverizing chamber 6 from the raw material supply device 11 by a screw conveyor or the like, and compressed air is injected from the pulverizing nozzle 3 to finely pulverize the pulverized raw material. The pulverized material is classified by a classification rotor 8 of a rotary classifier provided in the upper part of the pulverization chamber, and the pulverized material having a predetermined particle size range is discharged from the discharge pipe 5.

In the pulverizing apparatus of the present invention, the collision member 2 is placed in the rotating pulverizing chamber 6 of the fluidized bed type jet mill main body l, and the collision member 2 is connected to the pulverizing nozzle 3.
The compressed air energy is provided in front of the injection nozzle in correspondence with each injection nozzle, thereby making it possible to effectively utilize the compressed air energy that is not used and consumed for pulverization.

Regarding the installation position of the collision member, it is preferable that the center of the collision surface of the collision member be in a conical range having an apex angle of 20 degrees or less, assuming that the center direction of the jet air from the crushing nozzle is 0°. The direction is the center direction of the compressed air, that is, 0°. If the angle exceeds 20 degrees, the impact surface of the impact member will deviate from the flow of the injected compressed air at a greater rate, making the impact member ineffective. Regarding the distance, when compressed air is injected from a nozzle, the zone where the injected compressed air has effective energy is called the potential core zone (usually 5 times the inner diameter of the nozzle), but the tip of the collision surface of the collision member It is desirable that the distance to the tip of the pulverizing nozzle be within 5 times, preferably 2 to 3 times, the potential core zone. If the above-mentioned distance exceeds five times, the speed of the particles decreases and the collision energy decreases, or the air ejected from other nozzles is disturbed, conversely causing a decrease in the pulverizing effect.

Next, the shape of the collision member includes a spherical shape, a cylindrical shape, an oval shape, a dome shape, etc., but a spherical shape is preferable. Furthermore, the size of the collision member should be within a range that does not disturb the compressed air injected from other nozzles or the swirling flow, as explained above regarding the installation distance. It is desirable that the area of a plane or cross section perpendicular to the center direction is 50 times or less the cross-sectional area of the minimum inner diameter portion of the crushing nozzle.

Any wear-resistant material can be used for the collision member without any problem. In particular, wear-resistant alloys, wear-resistant surface-treated metals, ceramics, etc. are desirable.

Examples of collision member materials include alloys such as carbide, cobalt-based Stellite alloy, nickel-based Deloro alloy, iron-based Delchrome alloy, TriStyl alloy, and Tribaloy intermetallic compound, and ceramics. Examples include oxides such as alumina, titania, and zirconia, carbides such as silicon carbide and chromium carbide, nitrides such as silicon nitride and titanium nitride, and borides such as chromium boride and titanium boride.

A specific example of pulverization using the pulverizer of the present invention is shown below.

A pulverizer shown in FIGS. 1 and 2 was used. This fine grinding device has a grinding chamber diameter of 350 m+*φ, a grinding chamber cylindrical part height of 700 am, a center height of 1100 mm, a discharge pipe with an inner diameter of 100 IllIlφ in the center of the grinding chamber, and 72 blades with a diameter of 1481 mm. It had a classification rotor.

In addition, the grinding nozzles on the circumference of the grinding chamber are four Laval nozzles with an inner diameter of 5.2 mm and installed in the direction of the center of the grinding chamber, that is, so that the four jet airs intersect at the center of the grinding chamber, and the raw material is transported to the bottom of the grinding chamber. Grinding was carried out under the following conditions.

Example 1 Collision member Number: 4 Installation distance: 80mm Shape: Cylinder size: l 6. myiφX35mm material
5LIS304 Grinding conditions Grinding pressure 7.6 kg/cdG Exhaust air volume 11-12 m3/min Hammer mill crushed product of toner material for electrophotography (weight average particle diameter D, .-300
~500ρ) as a raw material, and the weight average particle size Dso (hereinafter referred to as
The particle size distribution was measured using a Coulter Counter TA-n (
(manufactured by Coulter Electronics). The results are shown in Table 1.

Comparative Example 1 The conditions were the same as in Example 1, except that no collision member was provided in the crushing chamber. -1lInR was ground. The results are shown in Table 1.

Example 2 The conditions were the same as in Example 1, except that the center of the collision surface of the collision member was placed precisely in the direction of the jet center of the crushing nozzle.

It was pulverized to -11a+.

Example 3 D 50. under the same conditions as Example 1 except that the center of the collision surface of the collision member was shifted horizontally by [5°] from the injection center direction of the crushing nozzle toward the outer peripheral direction of the crushing chamber. It was ground to -11ET+.

Example 4 Pulverization was carried out under the same conditions as Example 2 to obtain D50-11, except that the installation distance of the collision member (distance between the tip of the collision surface of the collision member and the tip of the crushing nozzle) was set to 60III11.

Example 5 The conditions were the same as in Example 2, except that the installation distance of the collision member was 140 mrs. Grinding was carried out to give -11 addition.

Example 6 The conditions were the same as in Example 4 except that the shape of the collision member was spherical (16 mm diameter), and pulverization was carried out to give o-11JI.

Example 7 The shape of the collision member was a square prism (16 mm x 16 mm x
D under the same conditions as Example 4, except that the flat part of the square prism was installed so as to face the crushing nozzle.
It was pulverized to so-11/Jl.

Example 8 Except that the shape of the collision member was spherical (3 (1 mmφ)),
The same conditions as in Example 4 were used. It was crushed to a length of -11 m.

Example 9 Except that the shape of the collision member was spherical (37a+mφ),
Under the same conditions as in Example 4, pulverization was carried out so that o=Ll.

The results of the above Examples and Comparative Examples are shown in Table 1.

As is clear from the comparison of the margin examples and comparative examples below, by installing a collision member in the crushing chamber of a fluidized bed jet mill,
It can be seen that the energy consumption for pulverization can be reduced and a pulverized product with a sharp particle size distribution can be obtained.

From the comparison of Examples 1 to 3, the installation position of the collision member (deviation of the center of the collision surface of the collision member from the direction of the crushing nozzle jet center)
By optimizing the pulverization energy consumption, it is possible to further reduce the energy consumption.

Judging from the diffusion state of compressed air in the crushing nozzle (Laval tube) and the results of Example 3, the range of the installation position of the collision member is within ±10@ from the center direction O@ of the nozzle (i.e.,
(a conical range having an apex angle within 20° from the center of the collision surface of the collision member in the direction of the center of the jet air from the crushing nozzle)
If so, the energy of compressed air can be used effectively, and preferably 0@.

From the comparison of Examples 2.4.5, it was confirmed that the crushing energy consumption could be further reduced by optimizing the installation distance of the collision member. The optimum installation distance range varies depending on the powder used, but it can be used not only in the potential core zone, where the energy of the compressed air injected from the crushing nozzle is maximum, but also in the particle entrainment, acceleration zone, and injected from other crushing nozzles. Considering the interference with the compressed air flow, the potential core zone is 26 m.
11 (5×5.2 mm: nozzle inner diameter), and the range of 5 times or less is 0 to 130 mm, and it is preferable to fall within this range.

From the comparison with Examples 4.6.7, it was confirmed that the crushing energy consumption could be further reduced by optimizing the shape of the collision member. The shape of the collision member is preferably a shape that does not disturb the compressed air flow injected from the crushing nozzle, and it is found that spherical, oval, cylindrical, dome, and particularly spherical shapes are effective.

Furthermore, from a comparison of Examples 8 and 9, it was confirmed that by optimizing the size of the collision member, the energy consumption for crushing could be further reduced.

The size range of the collision member depends on the spread of compressed air injected from the crushing nozzle and the installation range of the collision member.
It can be seen that the cross-sectional area of the minimum inner diameter portion of the crushing nozzle is preferably 50 times or less. In the case of Examples 8 and 9, 50 times the area of the minimum inner diameter of the crushing nozzle is 1061 mm2 (-
1/4 x (5,2) 2x 3.14x50), Example 8 is 707 ++ ua2, Example 9 is 1075
This is number 2.

Example 10 Using the pulverizer used in Examples 1 to 9,
As collision members facing the four crushing nozzles, carbide (material WII40, manufactured by Hitachi Metals ■), powder high-speed tool steel (llAP40, manufactured by Hitachi Metals ■), Sialon (HCNIO, manufactured by Hitachi Metals ■), and Using 5US304 and under the same conditions as in Example 2, a hammer mill pulverized product of magnetic powder-containing resin (800-50 (IET+) was used as a raw material, and pulverization was performed at a raw material supply rate of 20 kg/hr for 4 hours, and the abrasion weight of the collision member was measured. Changes (wear degree) were measured.In order to eliminate the difference between each crushing nozzle, the position of the collision member was replaced every hour.
Measurements were taken. The results are shown in Table 2.

Table 2 Note) Wear degree: (W+-+ -W+) /W, -,
xlOO (1-1, 2, 3, 4) [V is collision member 1nf
fi (g), ■ is sampling time (hr))
As is clear from the above results (this carbide is 5US30
4, II A P 40 was 71.2 times, and Sialon was 55.4 times, and good wear resistance was obtained in all cases.

Effects of the Invention Since the pulverizing device of the present invention is provided with the collision member in front of each pulverizing nozzle in the injection direction as described above, energy consumption is reduced and pulverization with a sharp pulverized particle size distribution is possible. Furthermore, the use of wear-resistant materials makes it possible to crush highly abrasive powders.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an example of the pulverizing device of the present invention, and FIG. 2 is a longitudinal sectional view of an example of the pulverizing device of the present invention. ■... Fluidized bed jet mill body, 2... Collision member, 3... Grinding nozzle, 4... Compressed air chamber, 5...
Discharge pipe, 6...Crushing chamber, 7...Collision member support part, 8
... Classifying rotor, 9... Rotation drive device, 10... Coarse powder flying prevention ring, 11... Raw material supply device.

Claims (1)

[Claims] (1) In a pulverizing device consisting of a fluidized bed jet mill that is equipped with a rotary classifier above the pulverizing chamber and injects compressed air from a plurality of pulverizing nozzles inside the pulverizing chamber to pulverize solid materials,
A pulverizer characterized in that a collision member is provided in front of each pulverizing nozzle in a jetting direction so as to correspond to each pulverizing nozzle so that injected air collides with the pulverizing nozzle.