JPS6190753A - Method of pulverizing raw material by ball mill - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a raw material pulverizing method using a ball mill used for pulverizing tarinka, limestone, coal, etc.

[Problems with Prior Art] FIGS. 3 and 4 show a conventionally used ball mill. The ball mill body 1 has a diameter of 4 to 5 m and a length of 12 to 16 m.
n+ shell and a hollow shaft serving as the raw material inlet and outlet4.
It consists of trunnions 3a and 3b having a diameter of 5, and is horizontally supported by plain metal (not shown) at the hollow shafts 4, 5, and is rotated at around 15 rpm by a drive device (not shown). . A cast steel liner 8 is screwed over the entire inner surface of the shell 2. An end liner 15 is attached to the inner surface of the inlet side trunnion via a retainer 13.

The input Rossi coat 6 that feeds the raw material into the ball mill main body 1 is
It is inserted into the hollow shaft 4 by one notch. Inside the shell 2, a first die A7 flutter 1111 with a screen opening is installed vertically at approximately 1/3 of the total length of the shell from the inlet side, and the ball mill body 1 is 1st on the entrance side
The chamber Δ is completely connected to the second chamber B on the exit [ ] side. At the exit side end of the seal 2, a second diaphragm having a screen opening is provided vertically to the right of the powder discharge means.

An outlet casing 7 is provided covering the outer end of the hollow shaft 5 to receive the powder discharged from the hollow shaft 5. The first constriction Δ and the second chamber B have steel balls 1 with several different diameters.
0 is the apparent volume, and it is charged from the crystal manhole 14.14 with a culmness of 30% of the internal mill volume. As shown in FIG. 5, the first chamber A contains several types of steel balls 10 with relatively large diameters (for example, diameters of 6On+a+, 70mm, 80mm, 90mm).
The second chamber contains several types of steel balls 10 with relatively small diameters (for example, diameter 201+1111.30111111.4+
1 llln, 501 nlll) is input and the grinding is carried out using the main grinder. FIG. 6 is a system diagram showing the ventilation means. The suction blower 18 is a bag filter 17
and communicates with the upper part of the exit casing via the grid separator 16.

Raw materials such as cement clinker and limestone are fed into the first chamber of the ball mill through chute 6. 10 steel balls in a ball mill
As shown in Fig. 4, the raw material is lifted up as the ball mill body rotates and falls down due to gravity. At that time the first
In the chamber, the raw material interposed therebetween is mainly crushed by the impact force caused by the collision of the steel balls 10 with each other and the steel balls 10 with the surface of the liner 8. Further, in the second chamber, grinding of the raw material interposed between the steel balls 10 phase q or the steel balls 10 and the surface of the liner 8 is mainly performed by rotational contact between the steel balls 10 and the surface of the liner 8. The liner 8 used in the second chamber has a slightly sloped upper surface as shown in Fig. 3, and is arranged so that the thicker part faces the outlet side, forming a so-called classification liner. ing. Therefore, in the second chamber, due to the rotation of the ball mill, the steel balls 10 are sorted as shown in FIG. 5, that is, the steel balls 10 are arranged such that the diameter decreases from the inlet side to the outlet side.

In the first chamber, since the diameter of the steel ball 10 is large and the effect of the classification liner is almost negligible, a normal line 8 with a slope of P41: (7) is used on the -C-+- plane.

The lumpy or granular raw material introduced into the first chamber Δ is crushed and transferred to the outlet side while becoming powder.
1 and is discharged to the second chamber side through the screen [1 hole], and is roughly ground and becomes a fine powder while moving to the outlet side, and due to the discharge function of the second diaphragm 12, it is discharged to the second chamber side. 5 is discharged to the outlet side casing 7. Furthermore, to explain the raw material discharge capacity of the second diaphragm (almost the same for the first diaphragm), 12a
12h is the boss of the middle chamber, 12h is the lifter spread out from the outer surface of the post 12a, 12C is the ring, 12d is the beam lid 12h
The powder that has passed through the screen plate 1211 is lifted diagonally to one side by the lifter 12d, slides down the lifter 12dl, and then continues along the slope of the boss 12a. and is discharged into the hollow shaft 5. □Then, suction is performed from the outlet side by the blower 18, and the inside of the ball mill body 1 is ventilated from the inlet to the outlet. This is to prevent the inside of the ball mill from becoming abnormally high temperature due to heat generated by frictional heat, and to prevent dust generated inside the ball mill from flowing outside.

The powder and granular raw materials contained in the air sucked from the outlet casing are filtered through the grid, separator 16, and bag filter 1.
7, and only the air containing no dust is discharged to the outside air by a suction blower. As mentioned above, the second room B
Then, the granular raw material flowing from the first chamber A h) is pulverized while moving toward the second chamber outlet side. In the second chamber, the fine powder region in which 40 to 60% of the fine powder with a particle size composition of 88 micron pass of the raw material to be crushed occupies is an area of 1/2 to 2/3 of the exit angle of the entire length of the second chamber. This corresponds to a region where the diameter of the classified steel ball is 25 mm or less.

Generally, when a raw material is pulverized, its surface area increases and its surface activity increases, making it easier for the fine powders to adhere to each other and form lumps. Furthermore, since the raw material inside the ball mill is in a slow fluid state, the situation is similar to that inside a granulator, and many relatively soft lumps are generated.
When phase n or steel balls are interposed between wheelies 8, the mass is tamped down [^1 i j demons, steel balls 10 or liner 9
On the surface (=t), a so-called cauding phenomenon occurs (11) [The above phenomenon is called agglomeration of fine powder.

In order to prevent such agglomeration inside the ball mill, physically it is possible to increase the amount of ventilation inside the ball mill to make fine powder (12 methods have been suggested to get it out of the ball mill quickly, and chemically Generally, a method is used in which a so-called grinding aid is added to the raw material to be ground to improve the dispersibility of the fine powder and improve the flow.

However, the amount of airflow inside the ball mill causes a large pressure loss due to the partitions (1st and 2nd dies\7-7 rams) in the ball mill, and increasing the amount of airflow requires increasing the force of the suction blower. Since the target power 16 is increased by 11'l, there are limitations from this point of view. On the other hand, it is difficult to find the right amount of grinding aids for the raw materials to be ground, and they are often octavalent and may affect product quality.
There are limitations from that aspect.

[Object of the Invention] The present invention was devised in view of the problems of the prior art, and mainly aims to prevent the agglomeration of the raw material to be ground in the fine powder area on the exit side of the second chamber where grinding is performed. The object of the present invention is to provide a method for pulverizing raw materials using a ball mill that can prevent a decrease in pulverization efficiency and also save energy.

[Means for Solving the Problems] In order to achieve the above object, the raw material grinding method using a ball mill of the present invention includes a first chamber having a raw material inlet, a second chamber having a raw material outlet, and a boundary between the two chambers. A whole mill having a first and second diaphragm is rotated before the first raw material is discharged, and the air in the second chamber is sucked from the raw material outlet.Thus, the raw material is stirred together with steel balls in the first chamber. The raw material is mainly crushed, and the crushed raw material that passes through the screen of the first diaphragm and flows into the second chamber is stirred together with smaller steel balls.
; In the raw material grinding method using a ball mill t for grinding in step 1, a large number of small holes are bored in the liner facing the fine powder area at the outlet of the second v circumferential wall, and compressed air is introduced into the room through these small holes. Squirt 1! It is characterized by the fact that

[Example] Figure 1 shows the compressed air of the present invention 1! 2 is a sectional view showing a state in which the device is attached to the ball mill main body, and FIG. In addition, in the present invention, compressed air is ejected from a large number of small holes bored in the circumferential wall of the fine powder area on the exit side of the second chamber. The main body of the ball mill and the ventilation means have already been explained at the top of the prior art section, so their explanation will be omitted.

Also, for the same month, the same symbols as in the conventional example will be used.

First, the configuration will be explained with reference to FIGS. 1 and 2. Second
A wind box 21 that surrounds and covers the shell 2 is provided outside the shell 2 in the fine powder area of the chamber. The wind box 21 passes through the hollow shaft 5 on the outlet side of the ball mill main body,
and a pipe 28 that penetrates the outlet casing and projects to the outside.
is connected. A rotary joint 27 is attached to the outer end of the pipe 28, and the rotary joint 27 is connected via a pipe to a compressor or mill (not shown).

On the other hand, the shell 2 surrounded by the wind box 21 has ventilation holes 2 leading to each liner 8 attached to the inner surface of the shell 2.
4 is drilled. The live 8 is in airtight contact with the inner surface of the shell 2 at the periphery of the lower surface, and a depression 25 serving as an air passage is provided on the lower surface except for the periphery. liner 8
A jet hole 26 for compressed air is bored in the hole 26 to communicate the recess 25 on the upper surface and the lower surface. It is. The size of the spout 26 and the aperture ratio in the area are, for example, 2 to 3 mm in diameter and 0.
It is preferably about 1 to 0.2%, but is not limited to this and the optimum value varies depending on the properties of the raw material to be crushed.

Next, IJ action will be explained.

The compressed air from the compressed air source with a force of 1-7 k++/c■2Q is sent to the wind box 21 via the 171-tally join (to 27, arrangement 28), and then to the ventilation hole 24.
The powder passes through the depression 25 and is ejected from the ejection hole 26 into the ball mill in the fine powder region of the second chamber. The compressed air ejected from the ejection port 26 disperses the fine powder, activates the original state, and prevents agglomeration. At the same time, the fine powder is blown onto the ventilation inside the ball mill and discharged to the outside of the ball mill.

[Variation example] FIG. 7 shows a modification.

In this example, instead of one quind box, a ring-shaped header pipe 31 surrounding the outlet end of the shell 2, a plurality of header pipes 32 communicating with the header pipe 31 and extending in the direction of the shell generatrix, Compressed air is sent into the second chamber B using the header pipe 32 and a branch pipe 33 connecting the ventilation holes 24 and the like.

[Effects of the present invention] As explained above, the raw material grinding method using a ball mill of the present invention physically causes agglomeration of fine powder by jetting compressed air from the circumferential wall of the ball mill main body in the fine powder area of the second chamber of the ball mill. Because the structure is such that the fine powder is blown away and discharged out of the ball mill through ventilation, (1) unlike the use of conventional grinding aids, it is not limited by the physical properties of the raw material to be ground.

Q) It is possible to reduce the cost of the product because the use of expensive grinding aids can be completely eliminated or greatly reduced.

(3) By adjusting the optimal amount of air, it is possible to reduce the possibility of over-pulverizing the already fine powder in the ball mill.
The contact probability between the steel balls and the unpulverized granular raw material can be improved, thereby improving the crushing efficiency and saving the crushing energy.

(4) Since the fine powder is forcibly blown out and placed on the ventilation, the amount of ventilation can be saved, and the energy required for this purpose can also be saved.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing the main parts of the present invention, and Fig. 2 is a cross-sectional view showing the main parts of the present invention.
3 is a sectional view showing the conventional ball mill, FIG. 4 is a sectional view taken along line IV-IV in FIG.
The figure is an explanatory diagram showing the arrangement of steel balls in the first and second chambers, and the sixth
The figure is a system diagram of the ventilation means for ventilating the inside of the ball mill body, and FIG. 7 is a sectional view showing a modification. 1...Ball mill body 2...Shell 3...Trunion 4...Inlet side hollow shaft 5...Outlet side hollow shaft 6...Inlet chute 7...Outlet casing 8...Liner 10 ... steel ball 11 ... first diaphragm 12 ... second die 17 flamm 21 ... wind box 24 ... vent hole 25 ... depression 26 ... spout hole

Claims (1)

[Claims] (1) A ball mill is equipped with a first chamber having a raw material inlet and a second chamber having a raw material outlet, and has first and second diaphragms at the boundary between the two chambers and in front of the raw material outlet, and 2 By sucking the air in the room,
In the first chamber, the raw material is stirred with steel balls to mainly crush the raw material, and the crushed raw material that passes through the screen of the first diaphragm and flows into the second chamber is stirred with smaller steel balls. In a raw material grinding method using a ball mill that mainly grinds raw materials, a large number of small holes are bored in the liner facing the fine powder area near the outlet of the circumferential wall of the second chamber, and compressed air is jetted into the chamber through these small holes. A method for pulverizing raw materials using a ball mill, which is characterized by: