JPS6250187B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a dry tower mill.

The dry tower type crusher is, for example,
This is a known pulverizer also disclosed in No. ``Dry Tower Type Attrition Pulverizer''. As shown in Figures 1 and 2, this crusher has a shaft at the center of a closed circular column 1, a screw 3 is attached to this shaft, and a geared motor 4 moves the screw 3 to hold the contents. Rotate it in the upward direction. The feed ore is supplied in a constant quantity into the crusher by a rotary valve 5. Although pulverization is sometimes carried out using feed minerals, the pulverizer is usually filled with a pulverizing medium such as steel balls. The fed material to be crushed is lifted up by the screw 3 together with the grinding medium and falls along the wall, during which time it is pulverized by the grinding action of the grinding medium and the material to be crushed. Hereinafter, this pulverized product will be referred to as powder.

Powder is discharged outside the crusher, but in the crusher shown in FIG.
It is collected in The air flows from the air blower 6 to the crusher and is circulated again. In the pulverizer shown in FIG. 2, the powder is extracted from the bottom of the pulverizer through a slit (not shown) by an air flow from a blower 6, discharged outside the pulverizer, and collected by a bag filter 7.

In the conventional tower-type crusher described above, even if the feed amount of the material to be crushed is constant, the discharge amount is not constant, and the material to be crushed is crushed depending on the filling amount and packing density of the material to be crushed into the gaps between the crushing media. The ventilation resistance inside the aircraft fluctuates greatly,
There were drawbacks such as uneven discharge volume.

As a means of solving the above-mentioned drawbacks, the present inventors proposed that the bottom of the closed column of a tower-type crusher be partitioned with a perforated plate through which the powder passes, and that a powder retention chamber be provided below the perforated plate (particularly Gansho 58-45678).

In the above proposal, the powder discharge is good in any case, so the amount of powder extracted can be changed arbitrarily, and the level of the material to be crushed in the crusher can also be controlled to an appropriate level, making it easy to maintain the best crushing efficiency. It had a huge effect.

The present invention further focuses on the fact that the perforated plate is located at a position where the powder pressure inside the column and the pressure of the crushing medium (steel balls, etc.) are maximum, and devises the shape of the upper surface of the perforated plate. In particular, the purpose is to further increase the pulverizing efficiency of the tower-type pulverizer and to improve the abrasion resistance of the pulverizing media and the perforated plate.

In the crusher of the present invention, concentric multi-striped unevenness is carved on the upper surface of the perforated plate at the bottom of the closed circular column, and the pitch of the unevenness is larger than the diameter of the grinding medium, and the cross section of the concave part of the unevenness is larger than the diameter of the grinding medium. The curvature is approximately equal to the surface curvature of the grinding medium, and a large number of through holes are provided at least at the bottom of the recess for passage of objects to be ground.

The present invention will be explained below based on the drawings.

FIG. 3 shows a crushing device showing one embodiment of the present invention, which is equipped with a perforated plate 8 on the bottom surface. In FIG. 3, a is a vertical cross-sectional view, b is a cross-sectional view of a perforated plate, and c is a partially enlarged view of the X section in FIG. That is, on the upper surface of the perforated plate 8, grinding media 11 are continuously provided on the circumference around the central axis of the circular column.
Recesses (grooves) 8a having a curvature approximately equal to the surface curvature of a steel ball (such as a steel ball) are provided at equal intervals from the center to the outer periphery with a pitch larger than the diameter of the grinding medium 11. The concave portion is smoothly connected to the concave portion by a convex portion having an appropriate curvature, and the cross-sectional shape of the concave and convex portion is wavy. At least at the bottom of the recess 8a, preferably at the bottom of the recess and at the top of the projection, vertical through holes 12 through which the powder passes are bored at appropriate intervals over the entire surface of the bottom plate. Of course, the inner diameter of this through hole 12 is made smaller than the diameter of the grinding medium, but when the grinding medium 11 rotates along the recess,
It is necessary to have a size that does not cause falling resistance, and on the other hand, a size that does not cause clogging of the objects to be crushed.
The size, position, and number of the through holes 12 may be appropriately determined depending on the size of the grinding medium 11 used, the type of the object to be ground, the target particle size of the grinding, and the like.

The function of the perforated plate 8 of the crusher of the present invention is as follows. The in-column crushing media 11 grinds the material to be crushed at the maximum pressure at the bottom of the tower, but in a crusher equipped with a flat perforated plate at the bottom of the tower, the grinding effect in the portion of the maximum pressure is reduced.

In the present invention, the grinding medium 11 is provided on the upper surface of the perforated plate 8.
As shown in FIG. 3c, the crushing media 11 at the bottom of the tower is
is fitted into the recess 8a and driven and rotated by the screw, and performs an efficient grinding action between the grinding medium 11 and the perforated plate 8, and the ground powder is pushed out of the recess 8a by the grinding medium. It is discharged from the through hole 12 at the bottom. Therefore, the mill of the present invention has improved milling efficiency.

In addition, the grinder of the present invention has less wear on the grinding media and the perforated plate.

Next, to give a specific example, the inner diameter of the circular column is 1170 mm.
φ, (i.e., bottom plate diameter 1170 mmφ) using steel balls of 27 mmφ as the crushing media, blast furnace water slag with a particle size of 80% of 0.5 mm or more is crushed to produce slag powder (brain plate diameter). Value 4030cm ² /g)
I got it. The corrugation pitch on the upper surface of the perforated plate is 35 mm, the diameter of the holes is 7 mm, and the holes are bored at a pitch of 27 mm in the circumferential direction at the bottom of the concave part and the top of the convex part, and the total number of holes is approximately
I drove with 380 pieces. As a result of long-term operation, the pulverized powder did not clog the holes, and the powder flowed smoothly into the lower storage chamber. Overall, the movement of the pulverizing media and the flow of the material to be pulverized were improved, and the perforated plate Compared to when the top surface was flat, the crushing capacity was improved by about 3
%, and an improvement of approximately 2% in the amount of wear of the steel balls was observed. The causes of these improvements include the effect of the lowermost steel balls pulverizing while moving in the recesses on the upper surface of the perforated plate, and the effect of promoting powder extrusion.

As described above, the present invention improves the grinding function of the grinding medium on the top surface of the perforated plate compared to the conventional grinder using a smooth perforated plate, thereby increasing the grinding capacity and reducing the amount of wear and tear on the grinding medium. He made a considerable contribution.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of a dry tower type crusher;
FIG. 3 is a partially enlarged longitudinal cross-sectional view of part a, b a cross-sectional view of a perforated plate, and c a cross-sectional view of a perforated plate of an embodiment of the present invention. 1... Closed circular tower, 2... Cyclone, 3... Screw, 4... Geared motor, 5... Rotary valve, 6... Blower, 7... Bag filter, 8... Perforated plate, 8a... Recessed part, 9... Retention chamber, 10... Screw conveyor, 11... Grinding media, 12... Through hole.

Claims (1)

[Claims] 1 In a tower type crusher, a closed circular column is provided with a screw in the center, the bottom of the closed circular column is a perforated plate through which the material to be crushed passes, and a retention chamber for the material to be crushed is provided below this perforated plate. On the upper surface of the plate, multiple concave and convex grooves with a pitch larger than the diameter of the grinding medium are carved concentrically, and the curvature of the cross section of the groove is approximately equal to the surface curvature of the grinding medium, and at least the bottom of the groove is covered. A tower-type crusher characterized by having a large number of through holes for the passage of crushed materials.