JPS6287257A - Annular gap type ball mill - Google Patents

Abstract

1. Annular gap-type ball mill for continuously pulverizing in particular hard mineral substances comprising a closed grinding container housing a rotor whose outer surface defines with the inner surface of the grinding container a grinding gap containing grinding pellets, the top portion and the lower portion of the rotor being tapered in opposite directions, characterized in that the grinding container (12) is supported rotatably and connected to a rotary drive.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to an annular gap type ball mill for continuously grinding particularly hard mineral materials, which comprises a sealed grinding container housing a rotor therein, The present invention relates to an annular gap type ball mill, wherein a grinding gap is formed between the outer surface of the rotor and the inner surface of the grinding container, and the upper and lower parts of the rotor are tapered in opposite directions.

<Prior Art> Hard mineral materials (Mohs hardness of 5 or more) such as corundum, zirconium oxide, alumina, and silicon carbide have conventionally been mainly crushed using iron balls in a ball mill. Grinding requires considerable IJ while the material is resident in the grinding chamber, and all components and iron balls that come into contact with the grinding material are subject to very severe wear.Furthermore, the grinding process is noisy and Another disadvantage of ball mills is that wear debris from the iron poles can get mixed into the milled material, which must be cleaned using complicated and expensive chemical methods.

This kind of annular gap type ball mill (West German Open Publication 9)
Although the ball mill (No. 172848479) is an improvement over the conventional ball mill, it is unsuitable for finely grinding hard mineral materials and is economical only for grinding very soft materials such as chalk. Only. This is mainly due to the behavior of the grinding balls and the grinding pellets within the grinding gap.

The pulverized pellets are injected into the pulverizing cap from below together with the pulverized material, and are first moved upward in the pulverizing gap by the pressure of the feed pump, which presses the suspended pulverized material into the annular gap type ball mill, and then by the rotational movement of the rotor. As a result, no grinding operation takes place above the grinding gap due to the reduction in pump pressure and the sinking due to gravity. This may be avoided by increasing the pump pressure or the flow rate of the crushed material, but there is a strong possibility that the crushed pellets will be discharged together with the crushed material, resulting in a decrease in the crushing output. In the grinding material flow ■, more or less only the lower half of the grinding gap is used for the grinding operation, and only half of the theoretically obtainable grinding output is realized. Due to the dense packing, severe wear occurs on the surfaces of the rotor and the grinding vessel.There is a risk that the rotor may even become clogged, especially if the rotor and feed pump are not in use for a short period of time. This risk can be alleviated by providing an impeller at the lower end of the rotor in an annular gap type ball mill. Features that highlight the shortcomings of gap-type ball mills,
This causes a decrease in the efficiency of crushing work. Moreover, the impeller is exposed to severe wear caused by crushed pellets and crushed material. Time? A screen is used to hold the crushed pellets in the grinding gap, but if this screen becomes clogged with crushed material or crushed pellets, the discharge of the crushed material is obstructed and eventually cannot be discharged.

In Ike's known annular gap ball mill (West German Publication No. 2811899), a conical and annular ground material container, which forms a grinding chamber on its inner surface, is provided with a rotatable displacement body that is also conical and annular. It is equipped. The annular plate that prevents the displacement body from moving is provided with a return path for the crushed pellets, which extends obliquely outward. In this case, the pulverized pellets exhibit the unfavorable behavior described above, and although the pulverized pellets circulate, the pulverization operation is not carried out over the entire height of both parts of the pulverization gap. The crushed pellets in the crushing gap for feeding downward into the interior are crushed in the discharge direction (
In order to flow along with the flow of the material rather than against it, the grinding work should be carried out in this non-separate grinding gap. It is less effective than the other parts. As another example of the striking force, it is possible to drive the crushing container rotatably around the central axis. However, this method not only does not contribute to optimizing the grinding degree, but on the contrary, the residence time in the grinding gap is short because the crushed pellets flow downwards inside the grinding gap and upwards outside the grinding gap. This results in a decrease in pulverization efficiency. Furthermore, this type of annular gap ball mill is only suitable for processing ground material in a wet state, and cannot process dry material.

<Object of the Invention> The object of the present invention is to improve the planar annular gap type ball mill, which can process even hard mineral materials in a dry state.
By increasing the crushing efficiency within the crushing gap,
It is economical and technically completely crushable.

<Structure, operation, and effect of the invention> The above-mentioned problems are solved by the present invention in that the crushing container is rotatably supported and coupled to a rotational drive device.

The annular gap type ball mill of the present invention is composed of two rotating bodies having upper and lower parts tapered in opposite directions, and can dry any hard mineral material such as corundum, zirconium oxide, alumina, silicon carbide It is possible to crush even in the state of pulverization. This is because the crushing operation of the crushed pellets is performed over the entire height and width direction of the crushing gap. This is because the rotor and rotating grinding container are tapered in opposite directions, and by counteracting the centrifugal force in a dry state or the gravity of the ground pellets, the ground pellets do not sink inside the grinding gear knob and are The dynamic state is maintained on the outside by the grinding vessel and on the inside by the rotor. As a result, the grinding gap is used in an appropriate R state during the grinding operation.

This is because the rotation of the rotor and the grinding container is slow, and the crushed pellets are present in the entire height and width direction, and the rotation increases between the two rotating elements, which increases the grinding efficiency. This will make a contribution. Since the crushing effect is determined by influencing the speed of the two rotating elements or the speed of the crushed pellets in the crushing gap, by controlling the speed, it is possible to prevent the crushed pellets from being ejected from the crushing gap. , crush (
It is possible to adjust the four charges. At the largest diameter part of the crushing container, a large centrifugal force is exerted, which effectively prevents the crushed pellets from being discharged together with the crushed material, which makes it possible to use a screen, etc. (The material will go to the discharge port through the grinding gap. The ground material moving upward to the discharge port through the grinding gap between the rotor and the top of the grinding container does not contain any ground pellets, and therefore does not contain any ground pellets. Grinding (There is no need to separate electrolyte from the material. In the annular gap type ball mill of the present invention, the circumferential speed of the rotor and grinding container is relatively slow, so the residence time is long to some extent. In this way, the pulverized material between the pulverized pellets is hyperactive upwards very slowly;
As a result, the width of the particle spectrum of the pulverized material is determined. By using ground pellets of various sizes, the annular gap ball mill of the invention can be operated very satisfactorily. That is, the coarse and heavy crushed pellets properly crush the coarse crushed material at the bottom of the crushing gap, while the fine and light crushed pellets properly crush the fine crushed material at the top of the crushing gap. This is because centrifugal force and the force that tries to lift it increase as you move upward. Due to the relatively long residence time of the ground material in the grinding gap, the hard material is quickly ground into fine particles of the desired particle size and discharged in a continuous stream. The higher the grinding gap is filled, the more
The energy supplied to the rotor and grinding vessel is used more effectively and the annular gap ball mill can be operated more economically.

In an advantageous embodiment of the invention, the rotor and the grinding vessel are driven in opposite directions. In the grinding gap, especially in the largest diameter section, the rotational forces of the ground pellets and ground material increase, so that with this method the output is almost twice that of an annular gap ball mill with a rotor and a stationary grinding vessel. It is possible to obtain.

An additional rotation of the external body consisting of the grinding container and the lid in the opposite direction partially reverses the movement of the pellets in the grinding gap. That is, the pulverized material, which had been rotating uniformly in the direction of rotation of the inner rotor, begins to rotate in the direction of rotation of the outer body at the lower part of the grinding gear hub. The direction of rotation of the grinding pellets at the top of the grinding gap remains unchanged. A rotation direction reversal region with a width of about 10 mm is formed between the upper and lower pellets, where the pellets have a low agglomeration density and are almost stationary. Therefore, the shear forces which play an important role in the grinding effect occur virtually on the wall of the inner rotor in the lower part of the grinding gap and on the wall of the outer body in the upper part. As the speed of the external body increases, the rotational direction reversal position moves upward.

At the discharge port provided above the internal rotor, the direction of rotation of the fluid is reversed and a swirling flow is formed.

The pulverized pellets entering this area are taken into this swirling flow.

If the direction of rotation of the external body is the same as the direction of rotation of the internal rotor, the behavior of the crushed pellets in the mill will change.

For example, if the inner body rotates at 2080 revolutions per minute, the crushed pellets will move to the discharge area. Rashimo now asks the external body to rotate in the same direction every minute at most! It is possible to remove the crushed pellets from the discharge area at a speed of 70 revolutions. As the speed of the outer body increases, there are fewer grinding gaps in the discharge gap.

Due to the centrifugal force acting on the fluid, the level of fluid in the discharge area increases.

Due to the slow rotation of the outer body, a centrifugal force is established in the discharge gap at an accelerating rate and acts on all the fluid in the gap without reducing to zero in certain areas of the outer wall. Therefore, all crushed pellets are subjected to an acceleration force greater than the acceleration of gravity, and this centrifuge-like acceleration force separates the feed into the separation gap into light and heavy parts, thus separating the crushed pellets. It becomes possible to separate efficiently.

The crushed pellets flowing along the outer wall have a gravitational acceleration of 3.8
It will be subjected to twice the acceleration, allowing speedy separation even during high-density cleaning. Furthermore, the separation process in the discharge gap is not hindered by the formation of swirling flows.

The internal rotor does not need to be operated, and even if it is not operated, the arresting horn created by the crushing container, which is effective as an external rotating body, can achieve the above effects even if the crushing operation is carried out in a dry state. It is enough to push it.

For varying the grinding gap width it is convenient to support the rotor and the grinding container in a movable manner. Preferably, the shaft and the grinding vessel are movable transversely to their central axis to reduce one side of the grinding gap, or coaxially moveable to reduce the top or bottom of the grinding gap. Let it happen. By allowing the pulverized material and pulverized pellets to accumulate within the pulverization gap, the pulverized pellets can fully demonstrate their performance within the pulverization gap. It is also effective to change the grinding gap when grinding hard mineral materials.

It is possible to change the eccentricity of both members and move them relative to each other during rotation of the rotor and/or the grinding vessel to further improve the performance of the grinding operation. By tilting the central axes of the rotor and the crushing container to each other or at an angle to the vertical axis, it is possible to separate the crushed material more efficiently than the crushed pellets at the outlet of the crushed material. .

This is because centrifugal force holds the ground pellets below the upper outlet of the ground material. Many variations are possible by combining the variation of the grinding gap width and the mutual position of the central axes of both parts.

As mentioned above, by tilting the rotor and the grinding container with respect to the vertical axis, and by employing automatic switching f194M as described later, both members can be rotated in the same direction or in opposite directions. The efficiency of the annular gap ball mill can be further improved by avoiding rotation in the lt direction or by changing the milling gap width by moving them relative to each other. It is possible to crush the material in any state.

The inner surface of the rotatable grinding vessel and the outer surface of the rotor exhibit a fine texture, which indicates that they are neither very smooth nor very rough. Such fine irregularities can be obtained by applying a suitable coating to the surface, which acts as a protective layer against corrosion and wear.

To prevent the heat generated from accumulating, the rotor may be internally ventilated and the grinding vessel may be provided with a cooling jacket for fluid cooling.

<Example> Embodiments of the present invention will be described below with reference to the drawings.

The annular gap type ball mill 45 roughly consists of a rotatably supported crushing container 12 and a rotor 13.
3 is arm 11, replaceable motor bearing Il
a. It is suspended from an arbitrary support member 10 via a motor 17 and a drive shaft 16. Grinding container 12 and rotor 1
The upper and lower parts of No. 3 are shaped like truncated cones in opposite directions, and the height of the upper part is lower than that of the lower part. The rotor 15 is removably provided as an upper element on the lower part of the grinding vessel 12 and is provided at a distance from the upper part I4 of the rotor 13. This lid is formed to correspond to the conical slope of the upper part 14 of the rotor 13. The upper end of the upper part 14 is connected to a drive shaft 16 that supports the rotor 13, and is configured to freely float within the crushing container 12 and transmit the driving force of the motor 17 to the rotor 13. The crushing container 12 is attached to a bearing 37 via a member 38.
The hollow shaft 39 is rotated in the opposite direction to the rotor 13 via a belt pulley 40 provided at the lower end thereof. Lid 1
All of the inner surfaces of the crushing container 12 including the grinding container 5 are provided with wear-resistant and corrosion-resistant linings 18 and 19, and fine irregularities are formed on the surfaces thereof. Although fine irregularities are formed on the outer surfaces of the rotors 13 and 14, the details thereof will be omitted for the sake of brevity.

A parallel annular grinding gap is formed between the outer surface of the space between the rotors 13 and the inner surface of the lower part of the grinding container 12, and through the horizontal space formed between the flat bottom of the grinding container 12 and the rotor 13, It communicates with the supply port for pulverized material provided in the lower middle. A discharge gap 23 is also provided in parallel between the rotor top 14 and the lid 15 or its lining 19.

This gap 23 is provided over the entire height of the rotor upper part 14, but its width is narrower than the width of the grinding gap 20. The lower end of the downwardly widening discharge gap 23 and the upper end of the upwardly widening grinding gap 20 communicate with an annular chamber 24 . of this annular chamber 24.
The two-part wall and the lower wall are flat and parallel, and their outer end faces 25 are convexly curved. The annular chamber 24 is
Located at the separation joint between the lid 15 and the grinding container 12, the flow 15
It is opened by removing the . This separation joint 2
The spacer 27 inserted at 6 can be replaced by another 1'2 spacer, thereby making it possible to change the width of the grinding gap 20 and to raise and lower the grinding container 12 relative to the rotor 13.

The annular chamber 24 is accessed through an opening 28 provided in the furanone. The rotor 13 and the crushing container 12 rotate,
If the hard mineral material to be ground is introduced into the grinding gap 20 from below via the feed opening 21, the grinding gap can be filled with ground pellets through the opening 28.

Drive shaft 16 extends through a discharge chamber 29 provided within member 30. The wall of said member 30 is provided with a discharge opening 31 for the crushed material which is forced out of the discharge gap 23 into the discharge chamber 29 .

Also provided at the upper end of the member 30 is a flexible seal 32,33. The ground material is introduced into the stationary annular chamber 34 adjacent to the member 30 via the sealing piece 35 and is discharged through the outlet pipe 36.

When the annular gap type ball mill 45 operates, the rotor 13 is first rotated by the motor 17, and the grinding container I2 is driven in the opposite direction. The grinding material is then introduced into the grinding gap via the feed [ ] 21 in the three hollow shafts, after which
It is preferable that the crushed pellets are filled through the opening 28, or that the pellets are made of the same material as the crushed material.In this way, even if the crushed pellets are worn out, the crushed material will not be contaminated and high purity can be obtained. You will be able to obtain a substance. Rotor 13
Since the crushing volume 2 and 12 have a conical shape with opposite directions, the maximum circumferential speed is achieved at the maximum diameter part, and the generated centrifugal force prevents the crushed pellets from sinking in the crushing gap 20. The surplus of ground pellets will be collected in the annular chamber 24, resulting in the formation of a barrier layer, preventing the ground pellets from flowing out through the grinding gap 20. Since the crushing gap 20 is filled with crushed pellets over its entire height, 100% of the crushing gap is utilized for the crushing operation, and while the crushed material remains in the crushing gap 20, the maximum pulverization of the crushed material is achieved. It will be affected. The crushed pellets, which have become fine enough to pass through the discharge gap 23 due to wear, are recirculated to the annular chamber by centrifugal force, so that the powder discharged from the discharge port 31 does not contain crushed pellets and remains after washing, sieving, etc. A desired final state is obtained that does not require any processing.

The crushed pellets do not settle in the crushing gap, eliminating the possibility of difficulty in starting the rotor or blockage. Also, wear of the component parts is reduced. High crushing output for hard mineral materials is possible even with low energy input, and the residence time of the crushed material within the crushing gap can be adjusted by appropriately selecting the circumferential speed of the rotor and crushing container and the crushing gap width. It is. The degree of grinding is influenced by the particle size of the ground pellets, which can be varied as desired to carry out stepwise grinding. Because the supported grinding pellets in the lower part of the annular gap type ball mill are suitable for grinding the supported particles, while the fine grinding pellets in the upper part are suitable for grinding finer particles.

In the embodiment of FIG. 2, parts that are substantially the same as those of the embodiment of FIG.

The annular gap type ball mill 45a shown in FIG. 2 is different from the ball mill 45a shown in FIG. substantially provided,
The point is that the heights of the upper part +3b and the lower part 13c are approximately equal. Furthermore, no annular chamber 24 is provided. This is because, if the speeds of the rotor 13a and the crushing container 12a are appropriately adjusted, the crushed pellets will be held at the maximum diameter part by centrifugal force, and as a result, the crushing effect will be increased. Further, the rotor 13a is eccentrically moved from the rotation axis of the grinding container +2a through the bearing lla in the tr (i direction, that is, to the left in FIG. 2, so one side of the grinding gap 20a is narrower than the other side. The crushing effect is further increased.The crushed material and crushed pellets are accumulated in the narrow gap, and as the crushed material constantly moves upward, the crushing effect increases towards the discharge direction.Crushing Depending on the hardness of the material and the circumferential speed of the rotor and crushing container, crushing may be carried out by the friction of the crushed materials against each other without the need to add crushed pellets. The crushing container 12a is attached to a member 38a and rotatably mounted on a bearing 37a provided around a hollow shaft 39a.
9a is a driving boo! Connected to J40a. hollow shaft 3
A supply line 2+a is arranged in 9a as far as the lower region of the grinding gap 20a. Rotor 13a and crushing container 1
The axis of rotation of 2a may be inclined with respect to the vertical axis.

An automatic switching mechanism may be provided so that the grinding container 12a and rotor 13a are initially rotated in the same direction. When the maximum speed is reached, the rotor 13a or the grinding vessel +2a is moved eccentrically to each other to form a 1 mm wide grinding gap 20a on one side, and at the same time the grinding vessel +2a or the rotor 13a is switched to operate in the opposite direction. Subsequently, the crushing container 12a or the rotor 13a is returned to its original position and rotated in the same direction, and the above operation is repeated.

This method is especially recommended for the grinding of only ground material, as it is possible to obtain a high density of energy in a reduced grinding gap.

It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made by those skilled in the art. It should be understood that such modifications are included within the scope of the present invention as long as they do not depart from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an annular gap type ball mill according to the present invention, and FIG. 2 is a longitudinal sectional view of another embodiment of the annular gap type ball mill according to the invention, in which the grinding gap is variable and the maximum diameter No annular chamber is formed in the part. 12.12a-Crushing container, ■3, I3a Rotor,
15...Lid, 2o, 2Qa...Crushing gap, 2
1.21a... Supply port, 23... Discharge gap,
24 ・Annular chamber, 31...Exhaust port.

Claims (10)

[Claims] (1) An annular gap-type ball mill for continuously grinding particularly hard mineral materials, which is composed of a sealed grinding container and a rotor built into the grinding container, and has an inner surface of the grinding container and a rotor built in the grinding container. A grinding gap is formed between the outer surfaces of the rotor to accommodate the grinding pellets, the upper and lower parts of the rotor are tapered in opposite directions, and the grinding container is rotatably supported and connected to a rotational drive. An annular gap type ball mill characterized by: (2) An annular gap type ball mill according to claim (1), wherein the rotor and the grinding container are driven to rotate in opposite directions. (3) In the annular gap type ball mill according to claim (1) or (2), the rotor or the grinding container is supported so as to be movable in order to change the width of the grinding gap. An annular gap type ball mill characterized by: (4) An annular gap type ball mill according to claim (3), wherein the movement is possible during rotation of the rotor and/or the grinding container. (5) In the annular gap type ball mill according to any one of claims (1) to (4),
An annular gap type ball mill characterized in that the central axes of the rotor and the grinding container are inclined to each other at a certain angle. (6) In the annular gap type ball mill according to any one of claims (1) to (5),
An annular gap type ball mill characterized in that the central axis of the rotor and/or the grinding container is inclined with respect to a vertical axis. (7) In the annular gap type ball mill according to any one of claims (1) to (6),
An automatic switching mechanism is provided, whereby the rotor and/or
Alternatively, an annular gap type ball mill characterized in that the rotating direction of the crushing container is changed to enable the rotor to move relative to the crushing container, and this operation is repeated. (8) In the annular gap type ball mill according to claim (7), the grinding container and the rotor are initially rotationally driven in the same direction by an automatic switching mechanism,
When maximum speed is reached, the rotors or the grinding vessels move relative to each other to form a grinding gap of 1 mm width on one side;
At the same time, the grinding container or the rotor is switched to operate in the opposite direction, and then the grinding container or the rotor returns to its original position and rotates in the same direction, repeating this operation. Annular gap type ball mill. (9) In the annular gap type ball mill according to claim (8), the rotor or the grinding container is provided with a central flow path that opens in the lower region of the grinding gap, and the flow path An annular gap type ball mill characterized by being coaxially provided with a hollow drive shaft connected to a material inlet. (10) In the annular gap type ball mill according to claim (1) and any one of claims (3) to (9), the rotor and the grinding container are arranged in the same direction. An annular gap type ball mill characterized by being driven.