JPH038830B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an apparatus including a vertical mill for producing powder such as cement.

BACKGROUND ART FIG. 4 is a cross-sectional view of a powder manufacturing apparatus 2 comprising a typical prior art vertical mill 1. In the vertical mill 1, a table 4 having a rotation axis extending vertically is provided in a casing 3 having a roughly right cylindrical shape, and a plurality of rollers 5 are arranged on the table 4 at equal intervals in the circumferential direction. Ru. The roller 5 is pressed against the table 4 by a reduction device 6, and crushes the raw material supplied into the vertical mill 1 through the supply duct 7.

A cone 8 approximately in the shape of an inverted truncated cone is provided within the casing 3 and above the table 4. A large number of classification blades 9 are arranged at the upper end of the cone 8 in the circumferential direction. Each classification blade 9 forms an equal angle with the radial direction of the cone 8, and is provided so that the airflow that has moved radially inward via the classification blade 9 swirls in a fixed direction within the cone 8.
Further radially inward of the classification blade 9, the support member 1
A large number of rotary blades 11 are arranged on the rotor 0 in the circumferential direction.
The support member 10 is rotationally driven via a rotating shaft 13 connected to a drive device 12 .

In the ceiling plate 14 of the casing 3, a discharge duct 15 is formed in a radially inner portion of each rotor blade 11. In addition, gases from the pulverized materials that have reached the space 16 in the casing 3 directly below the ceiling plate 14 and radially outward of the classification blades 9 are discharged from the casing 3 via the air bleed duct 22 and the damper 17. It is extracted, mixed with the fine powder extracted from the discharge duct 15, and taken out as a product.

Further, an air blowing port 18 is provided below the table 4 of the casing 3, and gas is sent into the casing 3 through a blowing means 19 provided along the outer periphery of the table 4 to blow the crushed material into the casing 3. It blows upwards. Further, the table 4 is driven by a drive device 20.
Rotationally driven by.

In the powder manufacturing apparatus 2 having such a configuration,
The raw material supplied onto the table 4 from the supply duct 7 is transferred to the table 4 as the table 4 rotates.
and the roller 5 and are crushed. The pulverized material obtained by pulverization is blown upward within the casing 3 by the gas flow from the blowing means 19.

A portion of the pulverized material that has reached the space 16 is extracted to the outside of the casing 3 via the damper 17. The remaining crushed material enters the cone 8 via the classification blade 9 and swirls, and due to the centrifugal force generated at that time, the coarse powder swirls along the inner wall of the cone 8 and falls downward, and is returned to the table. 4 Returned to the top. That is, classification is performed.

On the other hand, the remaining crushed material heads toward the rotor blade 11, collides with the rotor blade 11, and is also classified. The fine powder obtained by classification reaches the inside of the rotary blade 11 in the radial direction and is taken out through the discharge duct 15. The fine powder thus taken out and the pulverized material extracted from the space 16 are mixed and taken out as a product.

Such a conventional powder manufacturing apparatus 2, which is used as a mill for grinding cement, etc., in which the particle size distribution has an important effect on product properties, has had problems with regard to the strength of the manufactured cement.
That is, there is a problem in that the so-called ultra-coarse powder, which is unnecessarily large in particle size and is contained in the pulverized material extracted from the space 16, is not removed.

In order to solve these problems, the applicant of the present invention proposed a powder manufacturing apparatus 2a as shown in FIG. The configuration of this powder manufacturing apparatus 2a will be explained. Parts corresponding to the powder manufacturing apparatus 2 in FIG. 4 are given the same reference numerals. The feature of this proposal is that the powder extracted from the space 16 in the vertical mill 1 is guided to the second classifier 21, and the coarse powder obtained by classification is returned to the vertical mill through the supply duct 7. 1, the fine powder is mixed with the fine powder from the discharge duct 15 and made into fine powder.

Since the powder manufacturing apparatus 2a has such a configuration, the problem with the prior art powder manufacturing apparatus 2 described with reference to FIG. 4, that is, the problem of ultra-coarse powder being included in the product, is solved. However, when manufacturing cement, for example, the product obtained by this powder manufacturing apparatus 2a has a particle size composition ratio of so-called intermediate particles of 10 to 30 μm that affects its strength, etc., compared to the desired ratio. was found to decrease.

Problems to be Solved by the Invention The purpose of the present invention is to solve the above-mentioned technical problems,
An object of the present invention is to provide a powder manufacturing apparatus equipped with a vertical mill capable of manufacturing powder having a desired particle size structure.

Means for Solving the Problems The present invention provides a vertical mill that has a first classifier in a casing that classifies the pulverized raw material, and an intermediate position of the first classifier with respect to the passing direction of the pulverized material and a first classifier that classifies the pulverized raw material. and a second classifier to which pulverized materials extracted from the downstream side of the container and mixed with each other are supplied, and the fine powder from the first classifier and the fine powder from the second classifier are mixed. This is a powder manufacturing apparatus equipped with a vertical mill, characterized in that the coarse powder from the second classifier is returned to the vertical mill.

Function The powder manufacturing apparatus according to the present invention includes a vertical mill. This vertical mill is equipped with a first classifier that classifies the pulverized material crushed within the vertical mill. In addition, in the vertical mill, pulverized materials are extracted from an intermediate position of the first classifier and a downstream position of the first classifier in terms of the passing direction of the pulverized materials, mixed with each other, and supplied to the second classifier. be done. The fine powder from the first classifier and the fine powder from the second classifier were mixed to form a product, while the coarse powder from the second classifier was returned to the vertical mill.

That is, the second classifier is supplied with fine powder extracted from the vicinity of the downstream side of the first classifier and crushed material extracted from an intermediate position of the first classifier and classified. Therefore, it is possible to prevent so-called ultra-coarse powder from being mixed into the resulting product. On the other hand, since the fine powder extracted from the downstream position of the first classifier is mixed in advance with the relatively coarse crushed material extracted from the middle position of the first classifier and supplied to the second classifier, The mixed powder contains more intermediate particles than fine powder, and also contains relatively coarse pulverized particles. Therefore, the width of the powder size distribution will also be widened. Therefore, regarding the particle size composition of the fine powder taken out from the second classifier, the width of the particle size distribution can be widened to a desired degree without reducing the proportion of intermediate particles.

Embodiment FIG. 1 is a sectional view of a powder manufacturing apparatus 26 equipped with a vertical mill 25 according to an embodiment of the present invention. The configuration of the powder manufacturing apparatus 26 will be explained with reference to FIG.
Roughly right cylindrical casing 2 of vertical mill 25
A table 28 having a vertical axis of rotation is disposed within the table 7 and is rotationally driven by a driving means 29 . Further, an air outlet 30 is provided near the casing 27 directly below the table 28.
The gas supplied from the table 28 flows through a ventilation means 31, such as a duct, which is provided below the table 28 and surrounding the table 28.
The air is blown up all around the area from below.

A plurality of rotatable rollers 32 are arranged on the table 28 at equal intervals in the circumferential direction. The roller 32 is elastically pressed by the pressure means 33 and is brought into pressure contact with the table 28 . A raw material supply gutter 34 extending from the outside of the casing 27 into the casing 27 is provided above the table 28 . An end of the supply duct 34 inside the casing 27 is arranged above the center of the table 28 .

Further above the table 28, a hollow cone 35, generally in the shape of an inverted truncated cone, is arranged coaxially with the vertical axis of rotation of the table 28. A lower end 36 of the cone 35 faces above the center of the table 28.

At the upper end of the cone 35, a large number of classification blades 37 are arranged at intervals in the circumferential direction. Each classification blade 37 is arranged at the same angle intersecting the radial direction of the cone 35, and the gas entering from the radial outside to the radial inside of the classification blade 37 is rectified by the classification blade 37, It is arranged to be pivoted within the cone 35. Further, rotary blades 38 having a rotational axis coaxial with the cone 35 are provided radially inward of the classification blade 37 at intervals in the circumferential direction of the support member 39. The support member 39 is rotationally driven by a drive device 40. In the ceiling plate 41 of the casing 27 , a discharge duct 42 is formed in a radially inner portion of the rotor blade 38 .

A plurality of air bleed ducts 44 are arranged at intervals in the circumferential direction on the ceiling plate 41 so as to bleed the crushed material from the space 43 directly below the ceiling plate 41 between the classification blade 37 and the rotary blade 38. . Each bleed air duct 44
A damper 45 is provided at each, and the two are connected to a second classifier 46 .

The second classifier 46 has a casing 47 having an axis extending in the vertical direction and having a generally inverted truncated cone shape;
The vertical mill 2 is connected to the lower end of the casing 47.
The discharge chute 4 communicates with the supply duct 34 of 5.
8, and the second classifier 46 is provided with a cylindrical supply duct 50 having an inlet 49 corresponding to the bleed air duct 44. Supply duct 50
is coaxial with the casing 47, for example, and the end opposite to the inlet 49 projects into the casing 47. This protrusion 51 can prevent the coarse powder that descends while rotating along the inner circumferential surface of the casing 47 from falling into the supply duct 50 .

Near the upper end of the casing 47 is a support member 54 that is coaxial with the casing 47 and fixed to a rotating shaft 53 that is rotationally driven by a drive device 52.
is placed. Swirling vanes 55 and 56 are fixed to the upper surface of the support member 54 at intervals in the circumferential direction. The swirling vanes 55 have a rectangular plate shape extending in the radial direction, and the swirling vanes 56 also have a rectangular plate shape extending in the axial direction of the casing 47. These swirl vanes 55 and 56 are arranged alternately in the circumferential direction of the support member 54.

The pulverized material supplied into the casing 47 from the inlet 49 is sent to the rotating blades 55, 5 which are rotationally driven.
6 and taken out from the casing 47 through the discharge duct 57. The fine powder taken out from the second classifier 46 is conveyed via the damper 58 and mixed with a portion of the fine powder conveyed from the discharge duct 42 of the vertical mill 25 via the damper 59 to form a product. It is said that

The remaining part of the fine powder taken out from the discharge duct 42 of the vertical mill 25 is supplied to the pulverized material extracted from the bleed air duct 44 and directed to the second classifier 46 via the damper 60, and mixed with The thus mixed pulverized material is supplied to the second classifier 46. Here, classification wing 3
7 and the rotary blade 38 constitute a first classifier.

The operation of the powder manufacturing apparatus 26 having such a configuration will be explained. The raw material to be crushed is supplied into the vertical mill 25 via a supply duct 34 and falls near the center of the table 28 . The fallen raw material is caught between the rotating table 28 and the rollers 32 and is crushed. The pulverized material is further moved radially outward by the centrifugal force accompanying the rotational drive of the table 28, and is transported upward within the casing 27 by the airflow through the air outlet 30 and the air blowing means 31. .

The airflow containing such pulverized material passes between the classification blades 37 having the above-described configuration and enters the cone 35. At this time, the air flow and the crushed material are
The liquid collides with the classification blade 37, is rectified, and rotates in a fixed direction within the cone 35. Due to the centrifugal force accompanying this rotation, the coarse powder in the pulverized material reaches the vicinity of the inner peripheral surface of the cone 35, descends while rotating, and returns to the table 35.
8 and crushed. In this way, the classification wing 3
Classification according to 7 is performed.

On the other hand, a portion of the remaining crushed material in the cone 35 follows the airflow discharged from the discharge duct 42,
It moves in the direction of the rotor blade 38. At this time, the relatively large part of the particles in the pulverized material is swirled within the cone 35 by collision with the rotor blade 38 or swirling airflow accompanying the rotational drive of the rotor blade 38, and is classified as described above. and returned to the table 28 again. The crushed material that does not descend within the cone 35 reaches the radially inner portion of the rotor blade 38 and is taken out from the discharge duct 42.

The pulverized material thus reaches the space 43 inside the cone 35 and radially outward of the rotor blade 38 and is extracted from the bleed air duct 44 via the damper 45, and is taken out from the discharge duct 42. It is mixed with fine powder and supplied to the second classifier 46. Inside the second classifier 46, swirling vanes 55 and 56 are rotationally driven, and it is possible to realize the same classification operation as the aforementioned rotary blade 38. Therefore, the coarse powder that has been classified and descends while swirling inside the casing 47 is returned to the vertical mill 25 via the discharge chute 48 and the supply duct 34 of the vertical mill 25, and is pulverized again. The remaining pulverized material that is not returned to the vertical mill 25 is transferred to the discharge duct 5.
7 and taken out from the second classifier 46.

FIG. 2 is a graph illustrating the effects achieved by the powder manufacturing apparatus 26 shown in the first diagram. This graph is a Rosin-Ramula diagram, and Figures 1 and 4
The pulverizing effect of each of the vertical mills 26, 1 in FIG. 5 and FIG. 5 is shown. With reference to FIG. 1, FIG. 2, FIG. 4, and FIG. 5, lines l0, l1, and l3 in FIG.
4 shows the particle size distribution of the pulverized material passing through measurement points A1, A2, and A3 in the powder manufacturing apparatus 2 shown in FIG. 4, respectively. Since the pulverized material that has just been pulverized and has not been subjected to the classification action passes through measurement point A2, its particle size distribution becomes almost linear in the Rosin-Ramula diagram, as shown by line 11 in Figure 2. As a whole, many pulverized materials with large particle sizes are included.

On the other hand, since the fine powder classified by the classification blade 9 and the rotor blade 11 passes from the measurement point A3,
As shown by line 13 in FIG. 2, it is understood that the particles contain many small-diameter pulverized particles and the width of the particle size distribution is narrow. Therefore, at the measuring point A1, through which the mixture of the pulverized material extracted from the bleed air duct 22 and the fine powder taken out from the discharge duct 15 passes, a wide particle size distribution is observed, as shown by line 10 in FIG. can get. However, line l0
^The particle size distribution shown by The result is that it also contains coarse powder.

In the powder manufacturing apparatus 2a shown in FIG.
Measurement points corresponding to measurement points A1 to A3 in the figure are given the same reference numerals. The particle size structure of the pulverized material at measurement points A2 and A3 in FIG. 5 is shown by lines l1 and l3 in FIG. 2, respectively, as in the case of FIG. 4. On the other hand, the particle size structure of the fine powder taken out from the second classifier 21 at the measurement point A4a is shown by line 12 in FIG. line l2
In the particle size configuration shown in , the width of the particle size distribution is relatively narrow because relatively coarse particles are removed by the second classifier 21 in line l1. In addition, the particle size composition at the measurement point A1a of the fine powder obtained by mixing the fine powder taken out from the second classifier 21 and the fine powder taken out from the discharge duct 15 is constant between line 12 and line 13 in FIG. It is shown by a line l4 synthesized at a ratio of . This line l4 has a gentler slope and a broader particle size distribution than line l3, which is slightly improved, but as mentioned above, for example, in the case of cement grinding, intermediate particles of 10 μm to 30 μm are It was found that the percentage was decreasing relative to the desired percentage.

Therefore, in the powder manufacturing apparatus 26 of this embodiment as described above, the particle size structure of the pulverized material in each step of classification will be explained below. Measurement points corresponding to those shown in FIGS. 4 and 5 are designated by the same reference numerals. Casing 27 of vertical mill 25
The particle size structure of the pulverized material at the measurement point A2 in the interior and the measurement point A3 regarding the fine powder taken out from the discharge duct 42 is shown by lines 11 and 13 in FIG. 2, respectively. On the other hand, the particle size composition at measurement point A4 regarding the pulverized material from the bleed air duct 44 is as follows:
This is indicated by line l2 in FIG. Furthermore, the particle size composition at the measurement point A5 after the pulverized material extracted from the bleed air duct 44 and the fine powder taken out from the discharge duct 42 are mixed is almost similar to the particle size composition at the measurement point A4a in FIG. Therefore, the second
A line 15 is obtained by combining line 12 and line 13 in the figure at a constant ratio. That is, compared to the particle size structure shown by line 12, the composition ratio of intermediate particles and below has increased, and the particle size structure has become wider because it contains pulverized particles with relatively large particle sizes.

The particle size composition at measurement point A6 regarding the fine powder taken out from the second classifier 46 is the line l in FIG.
6. This particle size configuration is line l5
Compared to the particle size composition shown in , relatively coarse particles are removed by the second classifier 46, so
The grain size structure is such that the coarse grain side is reduced. The fine powder taken out from the second classifier 46 and the discharge duct 42
The particle size structure at the measuring point A7 of the product mixed with the fine powder taken out from the sample is shown by line 17, which is a composite of line 13 and line 16 in FIG. 2 at a constant ratio. In this particle size structure, the proportion of intermediate particles has increased compared to the case where the specific surface area (the Blaine value; cm ² /g) is the same as line 14 showing the particle size structure of the product in FIG. The composition has also become broader.

In this embodiment, since the pulverized material to be mixed into the discharge duct 42 is taken out from the intermediate position 43 of the first classifier, so-called ultra-coarse powder can be removed, and the quality, such as the strength, of the manufactured cement can be significantly improved. can be improved. Also, the second classifier 46
The pulverized material is a mixture of the pulverized material extracted from the bleed air duct 44 and the fine powder taken out from the discharge duct 42. Therefore, the composition ratio of particles that do not contain so-called ultra-coarse powder and have an intermediate particle size in the particle size distribution is relatively high, and therefore the fine powder taken out from the second classifier 46 is also The composition ratio of pulverized materials with medium particle size is relatively high.

The fine powder taken out from the second classifier 46 and the fine powder taken out from the discharge duct 42 were mixed to form a product. Therefore, the particle size distribution of this product can also be configured such that there are relatively many pulverized particles having an intermediate particle size among all the pulverized particles. The angle formed with the radial direction of the classification blade 37 in the vertical mill 25, the rotational speed of the rotary blade 38, the rotational speed of the swirling blades 55, 56 in the second classifier 46, the opening degree of the dampers 45, 58, 59, 60, etc. By adjusting the particle size structure of the obtained product, it is possible to easily adjust the particle size structure of the obtained product.

In the above embodiment, the second classifier 46 was of a so-called dynamic type using swirl vanes 55 and 56, but it may be of a so-called static type as shown in FIG. Referring to FIG. 3, the static type second classifier 4
6a will be explained. Regarding this static type second classifier 46a, parts corresponding to the configuration of the second classifier 46 shown in the first figure are given the same reference numerals. The second classifier 46a includes a cylindrical outer cylinder 61 having a vertical axis, and an outer cylinder 6 connected to the lower part of the outer cylinder 61.
1 and a hollow inverted conical part 62 coaxial with the ceiling plate 63
These constitute the casing 47. In addition, a right cylindrical inner cylinder 64 coaxial with the outer cylinder 61
is provided to protrude inward from the ceiling plate 63 into the casing 47.

The outer cylinder 61 is located outside the inner cylinder 64 in the radial direction.
Classifying blades 65 are arranged radially inwardly at intervals in the circumferential direction. A hollow inverted conical truncated cone section 66 for collecting coarse particles is provided below the classification blade 65. The ultra-coarse powder from the inverted truncated cone section 66 is discharged from the discharge chute 48.

The classification blade 65 has a large number of classification blades 65a, 65b, ... 65n (65 is a general reference numeral) arranged in the circumferential direction between the classification blade 65 and the ceiling plate 63 in contact with the upper end of the inverted truncated conical part 66. will be placed. The classification blades 65 are rectangular plate-shaped and have a similar configuration to the classification blades 37 of the vertical mill 25. Each classification blade 65 is fixed to a drive shaft 67 and can be angularly displaced. The mode of classification can be changed. Such a so-called static type second classifier 46a
Even by using the above, it is possible to obtain the same effects as those described in the above-mentioned embodiments.

Effects According to the present invention as described above, regarding the vertical mill having the first classifier in the casing, the intermediate position of the first classifier and the first
The pulverized material is extracted from the downstream position of the classifier. The extracted pulverized products are mixed with each other and supplied to the second classifier. The fine powder from the first classifier and the fine powder from the second classifier were mixed to form a product, and the coarse powder from the second classifier was returned to the vertical mill.

Therefore, the pulverized product after pulverization in the vertical mill passes through the first classifier or the second classifier to become a product, so that it is possible to prevent so-called ultra-coarse powder from being mixed in. In addition, the fine powder from the first classifier is mixed with the fine powder from the second classifier to produce the final product, because the mixed pulverized material supplied to the second classifier has a relatively intermediate particle size composition. Most of the crushed material has a similar particle size, so the fine material from the second classifier also has a similar particle size distribution. Therefore, the product obtained contains a large amount of pulverized particles having a relatively intermediate particle size as described above, so that the quality of the product obtained can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 shows a powder manufacturing apparatus 26 according to an embodiment of the present invention.
2 is a graph explaining the classification operation of the powder manufacturing device 26, FIG. 3 is a front view showing a partial cross section of a second classifier 46a according to another embodiment of the present invention, and FIG. 5 is a front view showing the configuration of a powder manufacturing apparatus 2 of the prior art, and FIG. 5 is a sectional view of a powder manufacturing apparatus 2a proposed by the applicant in contrast to the prior art of FIG. 25... Vertical mill, 26... Powder manufacturing device, 37...
Classifying blade, 38... Rotating blade, 42... Discharge duct, 44
... Bleeding duct, 45, 58, 59, 60... Damper, 46, 46a... Second classifier, 48... Discharge chute, 50... Supply duct, 55, 56... Swivel vane, 57... Discharge duct.

Claims (1)

[Scope of Claims] 1. A vertical mill having a first classifier in a casing that classifies the pulverized raw material, and an intermediate position of the first classifier and a downstream position of the first classifier with respect to the passing direction of the pulverized material. and a second pulverized material extracted from and mixed with each other is supplied.
a classifier, the fine powder from the first classifier and the fine powder from the second classifier are mixed to form a product, and the coarse powder from the second classifier is returned to the vertical mill. A powder manufacturing device equipped with a vertical mill characterized by: