JPH0143577B2 - - 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 airflow is circulated from the blower 6 to the crusher 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,
Emissions are uneven.

The present inventors have conducted extensive research to improve this drawback, and have developed a pulverizer that can discharge powder extremely stably by improving the bottom extraction type pulverizer shown in Figure 2. It came to this.

Conventional bottom-drawing tower type crushers with horizontal outlet have an unsteady air flow, and once the powder stays at the outlet for more than a certain amount or for a certain period of time, , no powder comes out at all, and the grinder becomes clogged. In other words, not only is it impossible to control the amount of powder to be extracted, but this also impedes stable operation.

The present invention aims to provide a tower-type crusher that can smoothly and uniformly take out powder by cleverly eliminating this drawback.

The gist of the present invention for achieving the above object is to provide a tower type crusher comprising a closed circular column, a shaft rotating at the center of the closed column, and a screw attached to the shaft. This tower-type crusher is characterized by the addition of a mechanism for fluidizing it inside the tower.

Next, the present invention will be explained with reference to the drawings.

FIG. 3 is a partially sectional side view schematically showing an embodiment of the present invention.

Inside the closed circular tower 1, there is a screw 3 which generates a propulsive force upward, and is rotationally driven by a geared motor 4. The feed ore is fed in a fixed amount through a rotary valve 5. Depending on the type of feed ore, pulverization may be performed between feed ores, and if necessary, a grinding medium such as steel balls is filled in the circular column. The bottom of the closed circular column 1 is equipped with an air diffuser 10 through which fluidizing air passes.
The lower part thereof forms a pressure chamber 11, into which air for fluidization is sent from the blower 6.

The product pulverized by the air introduced from the aeration device 10, that is, the powder, is in a fluidized state in the upper part of the aeration device (this is called the grinding chamber 8). A feature of the present invention is that a fluidization mechanism consisting of a blower 6, a pressure chamber 11, and an air diffuser 10 is provided. The fluidized powder is discharged together with air to the outside of the pulverizer through a slit 9 which is a carryover outlet provided on the side of the closed cylinder.

Next, specific effects of the present invention will be explained by giving examples. The embodiment shown in FIG. 3 in which a fluidization device is added to the tower-type crusher is as follows.

Specifications of tower type crusher Geared motor: 95KW Tower diameter: 1170mm Tower height: 3500mm Screw diameter: 900mm Slit size: 20mm Grinding media: 17mmφ steel balls, 6t Type of material to be crushed: Blast furnace granulated slag Feed amount: 1.7t /h Specific surface area of product (Blaine method): 4041cm ² /g Air pressure in pressure chamber of fluidization mechanism: 0.4Kg/cm ² Air volume: 4m ² /min Required power: 4KW Aeration device: Perforated plate holes 2mmφ x 1100 pieces In the above embodiment, the air diffuser 10 is 2 mm.
A perforated plate with 1100 φ holes was used. The diameter of the holes in the perforated plate should be such that the powder does not fall into the pressure chamber 11 on the lower surface of the perforated plate, and the size on the upper surface of the perforated plate should be such that the grinding media (steel balls) can move easily, that is, do not get stuck in the holes. .

The air velocity in the pulverizing chamber 8 is 7 cm/sec, and the powder in the pulverizing chamber is fluidized and may be said to form a fluidized bed. From the crusher, slit 9
The powder passed through and discharged was transported to a classifier using transportation equipment (not shown) and classified, the product was recovered, and the coarse powder was returned to the pulverizer.

Note that the fourth example is a simple example of collecting powder.
The embodiment shown in the figure may also be used. FIG. 4 shows fluidized air being introduced to fluidize the powder in the grinding chamber 8, which is then passed through the slit 9 together with the powder into the chute 14.
A filter bag 13 is attached to the hopper 12 to allow air to escape from the filter bag.
The powder can be collected into the hopper 12 with simple equipment, and the collected powder can be sent to the classification equipment.

If the powder in the pulverizer is fluidized as described above, the powder will be discharged from the pulverizer in a steady manner, and the pulverizer will not be clogged at all, allowing stable discharge. In the conventional discharge method, that is, the method of drawing powder through a slit and drawing it out by suction ventilation (Fig. 2), when the grinder is operated with a raised level of material to be crushed in order to improve the crushing efficiency of the crusher, the ventilation is significantly hindered. This causes an obstruction to the flow of the material to be crushed. Therefore, the mill had to be operated at a lower level of the material to be ground, resulting in low grinding efficiency. Moreover, once the discharge amount becomes small, clogging of the material to be crushed occurs in the crusher. In addition, even if the level of the material to be crushed is lowered, drafts mainly occur near the crusher screw drive shaft, and it is difficult for the material to be crushed to reach positions far from the shaft. This results in a greater reduction in pulverization efficiency.

By fluidizing the powder in the grinding chamber, the present invention can stably discharge the powder from the grinder in a fluidized state, in other words, in a pulverizing state. It is possible to uniformly discharge the objects to be crushed that have fallen and are distributed over the entire cross section.

The present invention, configured as described above, brings about the following effects.

(1) By fluidizing the powder, the amount of powder discharged from the crusher can be made constant. That is, if the ore supply to the crusher is kept constant, powder can be discharged stably in accordance with the amount of ore supply without requiring any other means.

(2) Improved grinding efficiency and stable operation of the grinder can be achieved.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory diagrams of a dry tower type crusher;
FIG. 3 is a schematic cross-sectional side view of an embodiment of the present invention, and FIG. 4 is a side view showing an example of a discharged powder recovery device. 1...Closed circular tower, 2...Cyclone, 3...Screw, 4...Geared motor, 5...Rotary valve, 6...Blower, 7...Bag filter, 8...Crushing chamber, 9...Slit, 10...Diffuser, 11...Pressure air Chamber, 12...Powder hopper, 13...Filter bag, 14...Chute.

Claims (1)

[Claims] 1. In a tower-type crusher consisting of a closed cylinder, a shaft that rotates at the center, and a screw attached to the shaft, an aeration device that passes fluidizing air to the bottom of the closed cylinder to fluidize the powder in the tower. A pressurized air chamber is formed below the air diffuser, a blower is provided to supply fluidizing air to the pressurized air chamber, and an outlet through which the fluidized powder carries over is provided on the side of the closed cylinder. A tower-type crusher with the following features: