KR870002126B1 - Pulverization method - Google Patents

Abstract

A grinding process comprises; (a) crushing and breaking a solid material on a round rotating table; (b) coveying the resulting fine powder by means of an upwardly blown gs stream, to an air classifier at a speed sufficient to entrain the fine particles while allowing the coarse particles to fall from the round table; (c) guiding the fine particles of predetermined fineness to the outside through the air classifier; and (d) recycling the coarse particles to the round table. The gas flow speed is controlled so that the ratio of the amt. of solids which fall from the table to the amt. of entrained solids is 0.4-2.0.

Description

Grinding method of solid material

1 is a partial cutaway front view of a pulverization apparatus embodying the method of the present invention.

2 is a sectional view taken along the line A-A of FIG.

3 is a diagram showing the relationship between CF / P, W ratio, and P ratio.

4 is a diagram showing the relationship between the interval gas ejection rate, the P ratio, and CF / P.

* Explanation of symbols for main parts of the drawings

1: driving device 2: round table

3: grinding drying room 4: supply chute

5: roller 6: casing

8: opening part (round table space) 11: rotor blade

12: outlet 14: conveyor

15: bucket elevator

The present invention relates to a method of grinding a solid material.

Conventionally, by the gas which crushes and pulverizes the solid substance supplied to the rotating round table by roller or fire and blows it upwards below the space around the round table, the fine powder produced is conveyed to the air classifier installed above the round table, and the required delivery is carried out. There has been proposed a method of pulverizing the solid material which is to take out the fraction of the figure out of the system and convey the solid substance falling from the space around the round table to the round table as a suitable transporter.

Using such a conventional method, the cement raw material is supplied to the rotating round table, and is moved around the round table as centrifugal force with the rotation of the round table, during which part of the cement raw material is moved to the roller or the ball under pressure. By crushing and crushing. This pulverized cement raw material is scattered by the rising hot air fractionation when it reaches above the space around the round table.

At this time, relatively fine particles (particularly fine powder) are returned to the air classifier which is installed at the top of the round table by gas. Here, these particles are classified by an air classifier.

By this classification, only the fine powder of the desired powder degree is taken out of the system, and the remaining coarse powder is returned to a round table, and is crushed again.

In addition, relatively coarse particles (particularly, granulated matter) are returned to the center of the round table and are ground together with the coarse powder.

Therefore, as a characteristic of this kind of method, when crushing and crushing a round table cement raw material as a roller or a ball, the required round table rotational power is remarkably less than that of a tub mill, and is generally less than half, but the round table The amount and pressure loss of the hot air blown out through the surrounding space is increased, and the driving power of the fan sucking the hot air is also larger than the power required of the round table rotation. Therefore, the required power of the whole system is slightly smaller than that of the tube mill.

As another conventional method as described above, there is also a method in which the solid material at the above interval is dropped and returned to the center of the round table as a bucket elevator or the like. However, according to such a conventional method, it becomes difficult to crush or pulverize, so that the cement raw material stays for a long time in the apparatus employing this method. As a result, the rollers, balls, and the round table are worn out remarkably.

In addition, this conventional method is effective in reducing the maintenance cost burden of the apparatus and improving the operation rate even when handling cement raw materials that are not allowed to continue operation due to accumulation, but actively drop solid materials. It is not a technical idea.

Therefore, in the apparatus employing such a conventional method, the fall prevention of this solid substance, which moves at intervals around the round table, the conveyance of the fine powder to the air classifier, and the coarse particles to the round table center portion of the uncrushed material For example, the amount of gas, wind speed, etc. are greatly increased, and this power is hardly changed from the above apparatus.

Here, the inventors have investigated the influence of the fall amount / mass amount (= CF / P) of the solid material around the round table, and as a result, when the CF / P exceeds a certain value, the processing capacity suddenly decreases. I found out to increase.

Here, the inventors of the present invention have an important requirement for drying a solid substance containing a constant amount / gas weight (P / G) of water, but for the pulverization, only the CF / P is used to provide the best range of the pulverization treatment capacity and the required power. The inventors have found out what constitutes a prescribed condition, and the present invention has been devised.

원탁 주위에서의 고형물질의 (CF/P)

2.0으로된 구성을 가진 것이다.That is, this invention crushes and crushes the solid substance supplied to the rotating round table as a roller or a ball, and conveys the produced fine powder to the air classifier installed above the round table by the gas which ejects from below the said round table periphery. In the grinding | pulverization method which takes out the powdery powder powder out of the system, and conveys the solid substance which falls from the periphery of a round table to the said round table with a suitable transport machine, 0.4

Of solids around the round table (CF / P)

It has a configuration of 2.0.

As a result, only relatively fine particles are scattered upward by the gas in the crushed material which is moved by the centrifugal force due to the rotation of the round table. Among them, the coarse powder is scattered to the circumferential wall and is returned to the round table. Here, the fine powder passing through the air classifier is discharged from the gas outlet to the outside of the pulverization apparatus. Therefore, according to this invention, pressure loss and fan power can be reduced, and reduction of maintenance cost, equipment cost, etc. can be aimed at.

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described based on drawing.

In FIG. 1 and FIG. 2, reference numeral 1 is a driving device, whereby the round table 2 is rotated into the horizontal plane. Moreover, the grinding drying chamber 3 is arrange | positioned above this drive device 1. In this drying chamber 3, the chute 4 which supplies a granular material is fixed through the casing 6. Reference numeral 5 denotes several rollers rotating about the side 7 passing through the casing 6. This roller 5 is made to rotate with friction with the rotation of the round table 2.

In particular, this roller 5 presses and grind | pulverizes the granular material layer supplied to the said round table 2 in the inside of the drying chamber 3.

In addition, an annular opening 8 is formed around the round table 2 to facilitate ventilation and drop of coarse particles between the casing 6, and a discharge passage 9 is provided directly below the opening 8. A hot air chamber 10 for supplying gas to the opening 8 is provided. Further, above the pulverization drying chamber 3, there is provided a rotor blade 11 which is rotated by a motor concentrically with the round table 2 and an air classifier 13 having a fine powder-containing gas outlet 12 upward. Further, reference numeral 14 denotes a mechanical conveyor linked to the discharge path 9, and 15 denotes a bucket elevator for transporting the coarse particles discharged as the conveyor 14 to the chute 4.

Next, the operation of the embodiment configured as described above will be described.

The exhaust gas of the suspension-free heater (not shown) of the calcination apparatus is blown into the pulverization drying chamber 3 through the hot air chamber 10 and the opening 8 by a suction fan (not shown), and is rotated by the round table 2. Due to the generated centrifugal force, only relatively fine particles are scattered upward from the crushed matter that is moved to and reached the opening 8.

The scattered particles are led to the air classifier 13 to form a swirl flow by the rotor blades 11 of the classifier 13 so that the coarse powder is separated and discharged from the upper center fine powder-containing gas outlet 12 to the outside of the grinder. do.

On the other hand, the granular material supplied from the granular material supply chute 4 to the center portion of the round table 2 is diffused around by the centrifugal force generated by the rotation of the round table 2. In the meantime, the granulated material caught between the round table 2 and the roller 5 by the force of the roller pressing downward is crushed.

In addition, the hot air is about the amount necessary for drying, and relatively fine particles among the crushed matters which are moved and reached by opening of the openings 8 by blowing at an upward wind speed of 10-25 m / s at the openings 8 are described above by the gas ejection. As one scattered, part of it is led to the air classifier 13 and the rest is returned to the round table 2.

At this time, the relatively coarse particles which are not scattered in the opening 8 fall from the opening 8 and fall onto the conveyor 14 through the discharge path 9 and are transferred to the supply chute 4 by the basket elevator 15. . In addition, the powder guided to the air classifier 13 is hit by the rotor blade 11, whereby the coarse powder having a centrifugal force is scattered to the circumferential wall, falls softly on the circumferential wall and is transported onto the round table (2). do. On the other hand, the fine powder which passed the rotary blade 11 is discharged | emitted from the upper fine powder containing gas discharger 12, and it collects as a fine powder in the collector which is not shown in figure.

원탁 주위에서의 고형물질의 CF/P

2.0의 조건으로 분쇄하는 것이, 장치비, 보수비, 운전비등을 종합적으로 감안하여도 가장 좋은 것이다.Further, in the above embodiment, 0.4

CF / P of solids around the round table

Grinding under the condition of 2.0 is the best even considering the equipment cost, maintenance cost, and operation cost as a whole.

Hereinafter, the reason will be described in detail.

If CF / P <0.4 is maintained, the placenta of the solid material moved around the round table will be scattered and returned to the center of the round table, or the placenta of the solid material will need to be gas returned to an air classifier installed above the round table. Therefore, it is necessary to increase the gas velocity of a large amount of gas and the space around the round table, and the pressure loss and the fan driving power are increased in the same manner as the conventionally known device of this kind.

However, when the CF / P becomes 2.0 or more, the pulverization treatment capacity is rather lowered, and the main driving power and the falling object transporting power of the pulverizing device are increased to increase the overall power unit (including the fan driving power in addition to the above).

This is evident in Figure 3.

Here, P in FIG. 3 is a constant quantity and W is a comprehensive power source.

This is believed to be due to the reduced amount of fines conveyed to the air classifier, whereby the fines are circulated for a long time in the main body of the pulverizer, the dropping material transporter, and the thickness of the round-table solid material layer is increased to decrease the pulverizing ability.

Next, the gas ejection speed will be described in the intervals.

The gas blowing rate is one of the main factors affecting CF / P. When the gas blowing speed is lowered, as shown by the curve A in FIG. 4, there is almost no falling object at 40 m / s or more, but below this, the falling amount CF gradually increases. In addition, as shown by the curve B of FIG. 4 at 25 m / s or more, the amount of P is almost unchanged, but decreases below it and becomes 10 m / s or less. Decreases rapidly to <0.5). In this case, this fall amount CF rapidly increases (curve A in FIG. 4).

2d에서는 오히려 증가한다(제3도).The integrated power unit W decreases in CF / P <2, but CF / P

In 2d it is rather increased (Figure 3).

In P / G, there is an appropriate value for conveying and classifying to an air classifier. In addition, when drying the solids, it is necessary to adjust the P / G by hot air temperature. Therefore, it is preferable to determine P / G in consideration of these conditions.

In this case, it is necessary to reduce the air volume as much as possible to reduce the power and increase the P / G.

Claims (1)

The solid material supplied to the rotating round table is crushed as a roller or a ball, and the fine powder generated by the gas ejected upward from the space around the round table is conveyed to the air classifier installed above the round table, whereby the required powder degree is refined. In the grinding method wherein the solid material which is taken out of the system and which falls around the round table is returned to the round table with a suitable transporter, 0.4.

Falling amount / quantity of solid substance around round table

Grinding method of a solid material, characterized in that 2.0.

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