JPH04243581A - Classifying apparatus - Google Patents

Abstract

PURPOSE:To obtain a product having a small mean particle size and particle size distribution reduced in the mixing ratio of a fine powder by preliminarily classifying and recovering the fine powder contained in a ground raw material before grinding said raw material. CONSTITUTION:The drive shaft composed of the hollow shaft 3 supported at the center of a classifying chamber in a rotatable manner and a plurality of the classifying blades 12 provided to said shaft so as to be integrally rotated along with the shaft are arranged to the classifying apparatus 2 arranged to the upper part of a grinder 1. Further, the fine powder discharge pipe 17 connected to the hollow pipe 3 is provided and a plurality of the guide vanes 13 freely revolvable around a vertical shaft 13a are arranged to the outer peripheries of the classifying blades 12 in a concentric circular state and an inverted cone-shaped guide cone 14 is provided under the guide vanes. The horizontal disc-shaped dispersing plate 15 covering the classifying blades 12 and the guide vanes 13 and a raw material scraper 15a are fixed to the hollow pipe 3 and a supply pipe 16 for charging a ground raw material is arranged to the casing 2a of the classifying apparatus 2 directly above the dispersing plate 15 and the scraper 15a.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention applies to materials to be crushed, such as chemicals (hereinafter referred to as classified raw materials), which are classified by a classification device attached to a crusher used in the ceramics industry and filler industry.
This relates to a classification device that separates powder into fine powder and coarse powder using airflow.

0002

[Prior Art] The purpose of a classification device is to use airflow to sort powder and granules crushed by a crusher into powders of a desired particle size to produce products.The classification principle is gravity classification, inertia force It is broadly divided into classification and centrifugal force classification. Of these, centrifugal force classification, which is suitable for large-volume classification of powder, includes a free-vortex type in which the airflow is swirled by making the shape of the classification chamber spiral, and There are two types: forced vortex type, in which the airflow is forcibly swirled by rotating blades installed in the air, and type that uses both free vortex and forced vortex, which is a combination of these two types.

[0003] In addition, there are two types of classification devices: those installed separately from the crusher to guide the powder and granules crushed by the crusher, and those installed separately from the crusher to guide the powder and granules crushed by the crusher, and those installed attached to the crusher to guide the powder and granules in the crushing chamber. There is an attached type that classifies particles by introducing them into a classification chamber by air conveyance, but the latter type has a wide range of applications, such as the vertical crusher shown in Figure 4 and the centrifugal fluid crusher shown in Figure 5. It is often used as an accessory.

[0004] Recently, along with the diversification of pulverized raw materials and the expansion of demand for ultrafine powder, the requirements for particle size distribution of products have become more sophisticated. There is an increasing demand for products that keep the amount of fine particles passing through within a certain ratio. To illustrate this case, for example, in the particle size distribution curve shown in FIG.
When a product is required that is pulverized and has a 0.1 μm pass of 1% or less (for example, curve Y), when the actually obtained product after pulverization becomes curve Z, the average particle size is satisfied. However, there were cases where the 0.1 μm pass was 1.1%, which exceeded 1%, resulting in a defective product.

[0005]

[Problems to be Solved by the Invention] As mentioned above, when a product is subjected to harsh pulverization conditions where the average particle size is fine to a certain extent and the proportion of fine powder mixed in is not very high, a regular classifier is attached. However, these conditions could not be achieved using a grinder using a conventional grinder, resulting in problems such as over-grinding.

[0006]

[Means for Solving the Problems] Therefore, in order to solve the above problems, the classification device of the present invention is arranged at the top of a vertical crusher or centrifugal fluid crusher, and is rotatable at the center of the classification chamber. It has a drive shaft made of a hollow tube that is pivotally supported on the drive shaft, and a plurality of circumferential classification blades that rotate integrally around the drive shaft.A fine powder discharge pipe is provided above the hollow tube, and the In order to give swirl to the air for classification, multiple guide vanes that can rotate around a vertical axis are arranged concentrically with the hollow tube, and an inverted cone-shaped guide cone is connected to the guide vanes. In the classification device equipped with the above-mentioned classification device, a horizontal disk-shaped dispersion plate covering the classification blades and guide vanes is fixed to a hollow tube, and a plurality of scrapers with a circumference perpendicular to the dispersion plate are fixed on the dispersion plate. In addition, the pulverized raw material supply pipe was installed in the casing of the classifier directly above the dispersion plate and scraper.

[0007]

[Operation] In the classification device of the present invention, the raw material is supplied to the classification chamber, falls onto the rotating dispersion plate, and overflows from the dispersion plate almost evenly around the circumference by the dispersion plate and scraper.
Most of the coarse particles fall downward. Then, the fine powder contained in the falling raw material swirls with the upward airflow from the crusher located below the classification device, passes through the guide vanes, and heads toward the classification blades. Here, the rotating classification blade receives a classification action, and the coarse powder in the fine powder is knocked off by the classification blade and cannot pass through the classification blade, but instead falls along the wall surface of the guide cone below and the inner surface of the casing. It is crushed in a crusher. Only the fine powder that has been subjected to the classification action and passed through the classification blades is discharged outside the machine from the fine powder discharge pipe via the hollow tube. In the crusher, both the coarse particles of New Feed and the coarse powder after classification are crushed, and only the powder with a relatively fine particle size is carried along with the upward airflow toward the guide vanes and classified by the classification blades in the same way as above. .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be explained below based on the drawings. 1 to 3 show embodiments of the present invention, FIG. 1 is a longitudinal cross-sectional view of a classification device, FIG. 2 is a plan view taken from II-II in FIG. 1, and FIG. 3 is a plan view taken from III-III in FIG. 1. FIG. The solid arrows in the figure indicate the flow of raw materials, and the dotted arrows indicate the flow of airflow.

In the figure, the classification device 2 is a vertical crusher 1a.
A hollow tube 3 is installed directly above a crusher 1 such as a centrifugal fluid crusher 1b, and a hollow tube 3 is connected to a pair of upper and lower bearings 4 concentrically with the crusher 1.
, 5 and is rotatably disposed. The bearings 4 and 5 are mounted on a pedestal 6 erected at the upper center of the casing 2a of the classifier 2.
A chain wheel 7 is attached to the upper end of the hollow tube 3, and a variable speed electric motor 9 is connected via a roller chain 8.
It is rotationally driven by a chain wheel 10 attached to the output shaft of. On the other hand, the lower part of the hollow tube 3 hangs down into the classification chamber, and as shown in FIG. A support 14a is provided on the outer periphery of the classification blade 12.
A guide cone 14 fixed to the casing 2a via
A plurality of guide vanes 13 that can be rotated and adjusted around a rotation shaft 13a fixed to the upper end flange are arranged, and the inclination of the guide vanes 13 is set in such a direction that the airflow that flows in synchronization with the rotational direction of the classification vanes 12 becomes a swirling flow. Ru. Note that the classification blades 12 may also be tilted in the same direction as the guide vanes 13 to form a spiral shape. Further, directly above the classification blade 12 and the fixed guide vane 13, there is a disk-shaped dispersion plate 15 having a size that covers both, and a dispersion plate 15 that extends radially in a radial direction orthogonal to the dispersion plate 15. A plurality of scrapers 15a are arranged equally on the circumference and rotated together with the hollow tube 3. A supply pipe 16 for supplying the pulverized raw material is provided at one point in the casing 2a directly above the distribution plate 15 and the scraper 15a. Furthermore, an air and fine powder discharge pipe 17 is provided above the upper end of the hollow tube 3 and connected to the pedestal 3 and the protective cover 7a of the chain foil 7, and is connected to a suction fan (not shown). Note that a truncated conical lid 3 is provided at the bottom of the hollow tube 3.
a to prevent short paths of airflow.

Next, the operation of the classifier 2 constructed as described above will be explained. When the raw material is introduced into the classification chamber (the area near the guide vanes and classification blades is called the classification chamber) through the supply pipe 16, the raw material that falls onto the dispersion plate 15, which is rotationally driven by the variable speed electric motor 9, is scraped by the scraper 1.
5a and the dispersion plate 15, the particles are distributed equally over almost the entire circumference, overflowing the dispersion plate 15, and as shown in Fig. 1, most of the large lumps fall downward in the direction of arrow A. . However, the fine powder contained in the raw material is accompanied by the airflow rising toward the guide vane 13 due to the suction force of a suction fan (not shown), and is classified toward the classification blade as shown by arrow B. As a result of classification, fine powder below the classification point passes through the inside of the hollow tube 3 and is discharged from the fine powder discharge pipe 17 (arrow D), but coarse powder above the classification point is rejected by the classification blade 12 as shown by arrow C. It slides down inside the guide cone 14 and heads toward the crusher 1. Similarly, the powder after pulverization is carried by the airflow passing through the guide vanes 13 and guide cones 14 toward the classification blades 12, where it is subjected to a classification action. The behavior after classification is as described above. Adjustment of the classification point is mainly done by controlling the rotation speed of the classification vane 12, and the inclination angle of the guide vane 13 is changed as a supplementary means, but this work is complicated as it has to be changed manually by interrupting operation. Therefore, it cannot be used frequently. In an actual machine where it is often desired to change the inclination angle of the guide vane 13 automatically during operation, a micromotor is used instead of the bearing 13b that supports the rotating shaft 13a of the guide vane 13 to remotely change the inclination angle of the guide vane 13. Change by operation.

As described above, in the classifier of the present invention, only the remaining granules and coarse powder after the fine powder contained in the raw material has been preliminarily removed by the classifier are supplied to the pulverizer. , prevents over-grinding, and has a relatively fine average particle size, as shown in curve Y shown in Figure 6, for example.
It is possible to obtain a product having a desired particle size structure with a narrow particle size distribution and less contamination with fine powder.

0012

[Effects of the Invention] The classification device of the present invention prevents over-grinding and obtains sharp fine powder with a narrow particle size distribution as refined powder. Furthermore, as over-grinding is prevented, the crushing efficiency is improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a classification device showing an embodiment of the present invention.

FIG. 2 is a plan view taken along line II-II in FIG. 1;

FIG. 3 is a plan view taken along III-III in FIG. 1;

FIG. 4 is a longitudinal cross-sectional view of a conventional vertical crusher.

FIG. 5 is a longitudinal cross-sectional view of a conventional centrifugal flow device.

FIG. 6 is a particle size distribution curve diagram showing an example after pulverization.

[Explanation of symbols]

1　Crusher 1a Vertical crusher 1b Centrifugal fluid milling device 2 Classification device 2a Casing 3 Hollow tube 4 Bearing 5 Bearing 6 Mount 7 Chain foil 8 Roller chain 9 Variable speed electric motor 10 Chain foil 11 Disk 12 Classifying blade 13 Guide vane 13a Rotation axis 13b Bearing or micro motor 14 Guide cone 14a Support 15 Dispersion plate 15a Scraper 16 Supply pipe 17 Discharge pipe

Claims (1)

[Claims] [Claim 1] A drive shaft consisting of a hollow tube arranged at the top of a vertical crusher or a centrifugal fluid crusher and rotatably supported in the center of a classification chamber, and a circle that rotates integrally around the drive shaft. A guide vane is provided on the outer periphery of the classification vane and is rotatable around a vertical axis for giving swirl to the classification air. In a classification device having a plurality of circumferences arranged concentrically with the hollow tube and an inverted cone-shaped guide cone connected to the guide vane, a horizontal disk covering the classification vanes and the guide vane. A shaped dispersion plate is fixedly attached to the hollow tube, and
A plurality of scrapers are fixedly disposed on the dispersion plate so as to be orthogonal to the dispersion plate, and a supply pipe for the pulverized raw material is disposed in the casing of the classification device directly above the dispersion plate and the scraper. Classifying device.