JPH0757326B2 - Pulverizer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a swirl flow type jet mill for crushing solid matter with compressed air energy, and in particular, a fine crushing apparatus capable of improving energy consumption in crushing and crushed particle size distribution. Regarding

2. Description of the Related Art A conventional swirl flow type jet mill (hereinafter, simply referred to as a jet mill) having a swirl crushing chamber jets compressed air from a crushing nozzle, and the energy of its high-speed air flow causes particles to collide with each other, resulting in solid matter. The particles were pulverized, and the particles were centrifugally classified by a swirling flow generated by a high-speed air flow to obtain particles having a desired pulverized particle size.

The advantage of the jet mill is that since it uses the injection of compressed air, a temperature drop occurs due to the adiabatic expansion action, and it is also possible to crush solids that dislike heat, and further, collision of particles, that is, surface crushing The main advantage is that it is suitable for fine pulverization rather than being main. On the other hand, the disadvantage is that a large amount of compressed air is used, so a large compressor is required, and the energy consumption for pulverization is 2 to 5 times larger than that of a mechanical mill, and moreover, the collision of particles is the main. Therefore, ultrafine powder is likely to be generated, and particles having a small number of collisions are discharged as coarse powder, so that the pulverized particle size distribution is widened.

Problems to be Solved by the Invention Among the above-mentioned disadvantages, an improvement for broadening the pulverized particle size distribution is to combine with a coarse powder classifier, pulverize to a size larger than the intended pulverized particle size with a pulverizer, and classify with a coarse powder classifier. Then
By returning the coarse powder to the crusher again and adopting the closed circuit crushing method to obtain the desired crushed particle size, crushing with a fairly narrow particle size distribution became possible. However, the energy consumption for grinding has not been improved yet.

The crushers described in Japanese Utility Model Publication Nos. 51-100374, 51-100375, 56-64754, and JP-A-58-143853 are of a single crushing nozzle-single collision plate type. Since the pulverizer alone has a drawback that the pulverized particle size distribution is wider than that of the jet mill, it is essential to combine it with the coarse powder classifier. Further, since it has a single nozzle, it has a drawback that it cannot be scaled up to a large-scale machine because the efficiency is lowered. The crusher described in JP-A-57-84756,
Since there is a communication tube, if the number of grinding nozzles is large,
The structure is complicated and not practical.

The present invention has been made for the purpose of ameliorating the above-mentioned drawbacks of the prior art.

That is, the object of the present invention is to install a collision member in front of the jetting direction of the crushing nozzle, effectively utilize two forces of collision between particles and collision of the particles with the collision member, and high crushing energy efficiency, Further, the present invention provides a fine pulverizing device for producing a pulverized product having a narrow pulverized particle size distribution.

Means for Solving the Problems The present invention, in a fine pulverizing device composed of a swirling flow jet mill for injecting compressed air from a plurality of pulverizing nozzles in a pulverizing chamber to pulverize a solid matter, in the injection direction forward of each pulverizing nozzle. , A collision member having a shape selected from a spherical shape, an oval shape, a cylindrical shape, and a conical shape is provided so that the injection air may collide, and the area of a plane or a cross section perpendicular to the central direction of the injection air in the collision member. Is 50 times or less than the cross-sectional area of the minimum inner diameter portion of the crushing nozzle.

The fine crushing device of the present invention will be described with reference to the drawings corresponding to the embodiments. The fine crushing device of the present invention is a swirling device in which compressed air is jetted from a plurality of crushing nozzles 3 in a swirling crushing chamber 6 to crush solid matter. Flow jet mill, and
The collision member 2 is provided in front of each crushing nozzle 3 in the ejection direction, and the air blown from the crushing nozzles collides with the collision member 2.

In the present invention, the installation position of the collision member is such that the center of the collision surface of the collision member is in a conical range having an apex angle within 20 ° when the direction of the center of the air blown from the crushing nozzle is 0 °. 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 not more than 5 times the potential core zone.

The collision member has a shape selected from a spherical shape, an oval shape, a cylindrical shape, and a conical shape, and includes an alloy, a surface-treated metal,
Alternatively, a ceramic material can be used. Further, as the size of the collision member, it is necessary that the area of a plane or a cross section perpendicular to the center direction of the blast air is 50 times or less than the cross sectional area of the minimum inner diameter portion of the crushing nozzle.

Action In the fine pulverization device of the present invention, the compressed air injected from the plurality of pulverization nozzles collides with the collision member provided in the front in the compressed air injection direction, so that the compressed air energy that is not used and is consumed effectively It can be used for crushing.

Embodiment An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view of the fine crushing apparatus of the present invention, and FIG. 2 is a sectional view taken along the line AA ′ of FIG. In the figure, 1 is the main body of the fine crushing device, 2 is a collision member, 3 is a crushing nozzle, 4 is a compressed air chamber, 5 is a discharge pipe, 6 is a swirling crushing chamber, and 7 is a collision member supporting component.

In the fine crushing apparatus of the present invention, the collision member 2 is provided in the swirling crushing chamber 6 of the swirling type jet mill main body 1 in front of the crushing nozzle 3 in the injection direction, corresponding to each injection nozzle, and is not used. The compressed air energy consumed in the process can be effectively utilized for grinding.

Regarding the installation position of the collision member, assuming that the direction of the center of the air blown from the crushing nozzle is 0 °, the center of the collision surface of the collision member is in the conical range having an apex angle within 20 °, and The direction of the center of the compressed air is 0 °. When the angle exceeds 20 °, the collision surface of the collision member is more likely to deviate from the flow of the compressed air injected, and the effect of the collision member is lost. Regarding the distance, when compressed air is jetted from a nozzle, a zone where the jetted compressed air has effective energy is called a potential core zone (usually 5 times the inner diameter of the nozzle). It is desirable that the distance from the tip of the crushing nozzle is within 5 times, preferably 2 to 3 times the potential core zone. If the distance exceeds 5 times, the air blown from other nozzles may be disturbed, or the swirling flow having a particle classification effect may be disturbed, which may cause a reduction in the crushing effect.

Next, examples of the shape of the collision member include a spherical shape, a cylindrical shape, an oval shape and a conical shape, and the spherical shape is preferable. Further, the size of the collision member is, in the same manner as the reason for the installation distance, a size in a range that does not disturb the compressed air injected from other nozzles or disturb the swirling flow, and specifically, The area of a plane or a cross section perpendicular to the central direction of the blast air is 50 times or less than the cross sectional area of the minimum inner diameter portion of the crushing nozzle.

The material of the collision member can be used without any problem as long as it is wear resistant. In particular, wear resistant alloys, wear resistant surface treated metals, ceramics and the like are desirable. As examples of the material of the collision member, alloys such as cemented carbide, cobalt-based stellite alloy, nickel-based Deloro alloy, iron-based delchrome alloy, tristil alloy, and triballoy intermetallic compound, ceramics Examples thereof include oxides such as alumina, titania and zirconia, carbides such as silicon carbide and chromium carbide, nitrides such as silicon nitride and titanium nitride, borides such as chromium boride and titanium boride, and the like.

A specific example of fine pulverization using the fine pulverizer of the present invention will be shown below.

The fine pulverizer shown in FIGS. 1 and 2 was used. This fine pulverizer had a diameter of 420 mmφ in the swirling crushing chamber, a height of 50 mm in the circumference of the swirling crushing chamber, and a height of 100 mm in the center, and had a discharge pipe having an inner diameter of 138 mmφ and a height of 74 mm at the center bottom of the swirling crushing chamber. The crushing nozzles in the circumference of the swirling crushing chamber are installed with four Laval nozzles with an inner diameter of 5.2 mmφ offset by 35 degrees from the center direction, and the raw material is supplied from the lid of the swirling crushing chamber by the action of an air injection nozzle. I did it. The fine crushing device consisting of the above jet mill and a micron separator (manufactured by Hosokawa Micron Co., Ltd.) were combined to form a closed circuit crushing system, and crushing was performed under the following conditions.

Example 1 Number of collision members 4 pieces Installation distance 22m Shaped cylinder Shaped cylinder 16mmφ × 35mm Material SUS304 Grinding condition Grinding pressure 7.6kg / cm ² G Supply pressure 6.0kg / cm ² G Exhaust air flow 11-12m ³ / min Secondary air air volume 1.2~1.5m ³ / min hammer mill crushed electrophotographic toner material (= 300 to 500 [mu] m weight average particle diameter D ₅₀₎ as a starting material, the weight average particle diameter D ₅₀
(Hereinafter simply referred to as D ₅₀ ) is pulverized under the above conditions so as to be 11 μm, and the particle size distribution is measured by Coulter Counter TA-II.
(Manufactured by Coulter Electronics).

The results are shown in Table 1.

Comparative Example 1 Crushing was performed under the same conditions as in Example 1 except that the collision member was not provided in the crushing chamber so that D ₅₀ = 11 μm.

The results are shown in Table 1.

Example 2 D ₅₀ = 1 under the same conditions as in Example 1 except that the center of the collision surface of the collision member was accurately set in the injection center direction of the crushing nozzle.
Crushing was performed so that the size became 1 μm.

Example 3 The crushing was performed under the same conditions as in Example 1 except that the center of the collision surface of the collision member was horizontally displaced from the injection center direction of the crushing nozzle by 15 ° in the outer peripheral direction of the crushing chamber so that D ₅₀ = 11 μm. went.

Example 4 Grinding was performed under the same conditions as in Example 2 except that the installation distance of the collision member (distance between the collision surface tip of the collision member and the crushing nozzle tip) was 80 mm, so that D ₅₀ = 11 μm.

Example 5 Pulverization was performed under the same conditions as in Example 2 except that the collision member was installed at a distance of 140 mm so that D ₅₀ = 11 μm.

Example 6 Grinding was performed under the same conditions as in Example 4 except that the shape of the collision member was spherical (16 mmφ), so that D ₅₀ = 11 μm.

Comparative Example 2 D ₅₀ = 11 μm under the same conditions as in Example 4, except that the shape of the collision member was a quadrangular prism (16 mm × 16 mm × 30 mm), and the flat portion of the quadrangular prism faced the crushing nozzle. Was crushed in the same manner.

Example 7 Grinding was performed under the same conditions as in Example 4 except that the shape of the collision member was spherical (20 mmφ), so that D ₅₀ = 11 μm.

Example 8 Crushing was performed under the same conditions as in Example 4 except that the shape of the collision member was spherical (37 mmφ), so that D ₅₀ = 11 μm.

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

As is clear from the comparison between the example and the comparative example, it can be seen that by installing the collision member in the swirling crushing chamber of the jet mill, crushing energy consumption can be reduced and a crushed product having 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 collision surface center of the collision member from the crushing nozzle injection center direction)
The energy consumption for pulverization can be further reduced by optimizing the above. Grinding nozzle (Laval tube)
Judging from the diffusion state of compressed air and the result of Example 3,
The range of the installation position of the collision member is within ± 10 ° from 0 ° in the central direction of the nozzle (that is, within 20 ° in the central direction of the blast air from the crushing nozzle from the center of the collision surface of the collision member. Within the conical range), the energy of compressed air can be effectively utilized, and it is preferably 0 °.

From the comparison of Examples 2, 4, and 5, it was confirmed that the grinding energy consumption can be further reduced by optimizing the installation distance of the collision member. The range of installation distance varies depending on the powder used, but the potential core zone where the energy of the compressed air jetted from the pulverizing nozzle is maximum, as well as the entrainment of particles, the accelerating zone and other pulverizing nozzles Considering the interference to the compressed air flow and the interference to the swirl dispersion zone, the potential core zone is 26 mm (5 × 5.2 mm: nozzle inner diameter), and the range of 5 times or less is 0 to 130 mm, It is preferably within this range.

From the comparison between Examples 4 and 6 and Comparative Example 2, it was confirmed that the energy consumption for grinding can 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 flow of compressed air ejected from the crushing nozzle, and is spherical, oval, cylindrical, conical,
It can be seen that the spherical shape is particularly effective.

Further, from the comparison between Examples 7 and 8, it was confirmed that the energy consumption for grinding can be further reduced by optimizing the size of the collision member. It is understood that the range of the size of the collision member is preferably 50 times or less of the cross-sectional area of the minimum inner diameter portion of the crushing nozzle from the spread of the compressed air injected from the crushing nozzle and the installation range of the collision member. In addition, in the case of Examples 7 and 8, 50 times the sectional view of the minimum inner diameter portion of the crushing nozzle is 1061 mm ² (= 1/4 × (5.2) ² × 3.14 × 50)
, And the Example 7 314 mm ^2, Example 8 is 1075 mm ^2.

Example 9 Using the milling equipment used in Examples 1-8,
Cemented carbide (material WH40, manufactured by Hitachi Metals, Ltd.), powder high-speed tool steel (HAP40, manufactured by Hitachi Metals, Ltd.), sialon (HCN)
10, Hitachi Metals Co., Ltd. and SUS304, under the same conditions as in Example 2, hammermill pulverized product (30) of magnetic powder-containing resin
(0 to 500 μm) as a raw material, the raw material supply rate was 20 kg / H, and pulverization was performed for 4 hours, and the change in wear weight of the collision member (wear degree) was measured. In order to eliminate the difference between the crushing nozzles, the position of the collision member was exchanged every hour and the measurement was performed. The results are shown in Table 2.

As is clear from the results above, carbide is 96.6% of SUS304.
2 times, HAP40 was 71.2 times, Sialon was 55.4 times, and good wear resistance was obtained in all cases.

EFFECTS OF THE INVENTION As is apparent from the above results, since the fine pulverization device of the present invention is provided with the collision member having the predetermined shape and size in the injection direction of each pulverization nozzle, the energy consumption is reduced, and the pulverization particle size is reduced. It enables crushing with a sharp distribution. Further, the wear-resistant material enables pulverization of powder having strong wear resistance.

[Brief description of drawings]

FIG. 1 is a plan view of an example of a pulverizing apparatus of the present invention,
FIG. 2 is a sectional view taken along the line AA ′ of FIG. 1 ... Main body of fine pulverizer, 2 ... Collision member, 3 ... Grinding nozzle, 4 ... Compressed air chamber, 5 ... Discharge pipe, 6 ... Swirl grinding chamber, 7 ... Collision member supporting parts.

Claims (4)

[Claims] 1. In a fine pulverizing apparatus comprising a swirling flow type jet mill for blasting compressed air from a plurality of pulverizing nozzles in a pulverizing chamber, the blast air collides in front of each pulverizing nozzle in the jet direction. As described above, a collision member having a shape selected from a spherical shape, an oval shape, a cylindrical shape, and a conical shape is provided, and the area of a plane or a cross section perpendicular to the center direction of the blast air in the collision member is the minimum of the grinding nozzle. A fine crushing device characterized by having a cross-sectional area of 50 times or less of the inner diameter portion. 2. The direction of the center of the air blown from the crushing nozzle is 0.
The fine crushing apparatus according to claim 1, wherein the center of the collision surface of the collision member is set in a cone-shaped range having an apex angle within 20 ° when the angle is defined as °. 3. The fine pulverizing device according to claim 2, wherein 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 of the potential core zone. 4. The fine crushing apparatus according to claim 1, wherein the material of the collision surface of the collision member is selected from alloys, surface-treated metals, and ceramics.