JPH04243583A - 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 component by preliminarily classifying and recovering the fine powder contained in a ground raw material before grinding the raw material. CONSTITUTION:The drive shaft composed of the hollow pipe 3 supported at the center of a classifying chamber in a rotatable manner and a plurality of the classifying blades 12 integrally rotating along with the drive shaft are provided to the classifying apparatus 2 arranged to the upper part of a grinder 1 and a fine powder discharge pipe 17 is connected to the hollow pipe 3. A plurality of guide vanes 13 freely rotatable around vertical shafts 13a are arranged to the outer peripheries of the classifying blades 12 in a concentric circular state and a guide cone 14 having an inverted conical shape and having two or more slits provided to the conical surface thereof is provided under the guide vanes 13. A 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.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a classification device attached to a pulverizer for pulverizing chemicals used in the ceramics industry and filler industry, and is a classification device that separates classified raw materials into fine powder and coarse powder by air flow. It is related to.

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 5 and the centrifugal fluid crusher shown in Figure 6. 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, since the 0.1 μm pass was 1.1%, exceeding 1%, there were cases where the product was defective.

[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. These conditions could not be achieved with the conventional crusher, which caused 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 by a 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 A plurality of guide vanes rotatable around a vertical axis for giving swirl to the classification air are disposed on the outer periphery of the blade concentrically with the hollow tube, and a plurality of guide vanes are provided on the lower part of the guide vane. A classifying device equipped with a guide cone in the shape of a substantially inverted truncated cone connected to the hollow tube, wherein a horizontal disc-shaped dispersion plate covering the classification blade and the guide vane is fixed to the hollow tube, and , a plurality of circumferential scrapers extending perpendicularly and radially in the radial direction are fixed on the distribution plate, and a supply pipe for the pulverized raw material is arranged in the casing of the classification device directly above the distribution plate and the scraper, The inverted truncated conical surface of the guide cone is provided with a plurality of slits around its circumference for passing upward airflow.

[0007]

[Operation] In the classification apparatus of the present invention, the raw material is supplied to the classification chamber via the supply pipe and falls onto the rotating distribution plate. The raw material on the distribution plate spirals outward due to the centrifugal force and the scraping action of the scraper provided on the distribution plate, overflows from the outer periphery of the distribution plate almost evenly around the circumference, and falls downward. At this time, most of the coarse particles of the raw material fall downward along the inner surface of the casing due to the action of gravity, but the fine powder contained in the falling raw material is caught in the upward airflow from the crusher located below the classification device. The liquid then rotates and passes through the guide vane to the classification vane. 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.
It slides down the wall of the lower guide cone in a spiral pattern or falls along the inner surface of the outermost casing and heads toward the crusher. At this time, the fine powder contained in the coarse powder that spirally slides and falls along the wall of the guide cone crosses the slits provided several times around the circumference on the slope of the guide cone several times. The airflow that rises from the slit is accompanied again by the airflow and is again subjected to the classification action toward the classification blade. The fine powder below the classification point that has been classified by the classification blade passes through the classification blade, passes through the hollow tube, and is discharged outside the machine from the fine powder discharge pipe. In the crusher, the aforementioned coarse particles of New Feed and the coarse powder after classification are both subjected to the crushing action, and only the powder with a relatively fine particle size rides on the upward airflow and heads toward the guide vane, where it is transported upward. It is classified using a classification blade in the same way as described above.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be explained below based on the drawings. 1 to 4 show embodiments of the present invention, in which FIG. 1 is a longitudinal 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. Plan view, Figure 4
FIG. 3 is a perspective view showing another embodiment of the guide cone. 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 plurality of guide vanes 13 are arranged on the outer periphery of the classification blade 12 and can be rotated around a rotating shaft 13a fixed to the upper end flange of a guide cone 14 fixed to the casing 2a via a support 14a. The inclination is set in a direction that makes the airflow flowing in synchronization with the rotation direction of the classification blade 12 into a swirling flow.

In the embodiment shown in FIG. 1, the conical surface of the guide cone 14 is provided with slits 14b extending downward along the slope at equal intervals around the circumference, and the airflow from below is guided through the slits 14b. Invades the inside of the cone 14. Further, as another example of the slits, as shown in FIG. 4, it is conceivable that the slits are arranged in a staggered manner in multiple stages horizontally on the conical surface. In either case, the fine part of the coarse powder that spirally slides down the conical slope of the guide cone 14 is carried by the upward air current entering the guide cone 14 from the slit 14b to the classification blade 12 again. The main role of the slit 14b is to collect the particles after they have been subjected to the classification action.

Further, directly above the classification vane 12 and the fixed guide vane 13, there is a disc-shaped dispersion plate 15 having a size that covers both, and a radial dispersion plate 15 arranged in a radial direction orthogonal to the dispersion plate 15. A plurality of scrapers 15a extending from the center are arranged equally on the circumference and are rotated together with the hollow tube 3. A supply pipe 16 for 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 3a is provided at the bottom of the hollow tube 3 to prevent short paths of airflow.

Next, the operation of the classification device 2 constructed as described above will be explained. When the raw material is introduced into 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 15a.
The centrifugal force acting on the dispersion plate 15 causes the particles to be equally distributed almost all around the circumference, overflowing the dispersion plate 15, and as shown in FIG. 1, most of the large lumps fall downward as indicated by arrow A. but,
The fine powder contained in the raw material is accompanied by an air current rising toward the guide vane 13 by the suction force of a suction fan (not shown), and is then directed toward the classification blade as shown by arrow B, where it is classified. 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. However, in the classification device of the present invention, since the guide cone 14 is provided with the slit 14b, a portion of the rising air from the crusher 1 enters the guide cone 14 through the slit 14b and slides down the conical slope in a spiral shape. The fine powder contained in the coarse powder is stirred up and entrained, and then passes through the guide vanes 13 to the classification blades 12 where it is again subjected to the classification action, thereby preventing the fine powder from going to the crusher 1. In this way, the large lump of raw material indicated by the arrow A mentioned above and the coarse powder that fell down the slope of the guide cone 14 are crushed by the crusher, and the crushed powder passes through the guide vanes 13 and the guide cone 14. Riding on the passing air current, it heads toward the classification blade 12 and receives a classification action. The behavior after classification is as described above. The adjustment of the classification point is mainly done by controlling the rotation speed of the classification blade 12.
As an auxiliary means, changing the inclination angle of the guide vane 13 is possible, but this operation requires interrupting operation and changing manually, which is complicated and 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, the inclination angle of the guide vane 13 is often changed automatically.
In place of the bearing 13b that supports the rotating shaft 13a of No. 3, a micromotor is used and the change is made by remote control.

As described above, in the classification device of the present invention, after the fine powder contained in the raw material is removed in advance in the form of preliminary classification by the classification device, the coarse powder after classification is once again passed through the slit of the guide cone. The fine powder contained in the coarse powder is collected on the updraft, and only the remaining granules and coarse powder are fed to the crusher, which is ideal for preventing over-grinding. As shown by curve Y, it is possible to obtain a product having a desired particle size structure with a relatively small average particle size, a narrow and sharp particle size distribution with little contamination of fine powder.

[0014]

[Effects of the Invention] In the classification device of the present invention, the fine powder contained in the raw material is reliably collected and used for pulverization before being pulverized, so over-pulverization is prevented and sharp particles with a narrow particle size distribution are produced. Fine powder is obtained as fine 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 perspective view showing another embodiment of the guide cone of the classification device of the present invention.

FIG. 5 is a longitudinal cross-sectional view of a conventional vertical crusher.

FIG. 6 is a longitudinal sectional view of a conventional centrifugal flow device.

FIG. 7 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 14b Slit 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. It has a plurality of classification blades around the circumference, a fine powder discharge pipe is provided above the hollow tube, and a guide rotatable around a vertical axis is provided on the outer periphery of the classification blade for giving swirl to the air for classification. A classification device comprising a plurality of vanes disposed concentrically around the hollow tube, and a guide cone in the shape of a substantially inverted truncated cone connected to the guide vane at the lower part of the guide vane. ，
A horizontal disc-shaped dispersion plate covering the classification blades and guide vanes is fixed to the hollow tube, and a plurality of circumferential scrapers extending vertically and radially on the dispersion plate are fixed. At the same time, a supply pipe for the pulverized raw material is arranged in the casing of the classification device directly above the dispersion plate and the scraper, and a plurality of slits are provided on the circumference of the inverted truncated conical surface of the guide cone for passing upward airflow. Device.