CN87107400A

CN87107400A - Ball mill automatic ball feeding device

Info

Publication number: CN87107400A
Application number: CN87107400.1A
Authority: CN
Inventors: 穴田信二
Original assignee: JGC Corp
Current assignee: JGC Corp
Priority date: 1986-12-13
Filing date: 1987-12-12
Publication date: 1988-06-29
Also published as: CN1011763B; JPS63151364A; JPH0645012B2

Abstract

An automatic ball supply equipment for a ball mill, which has a mechanical device that supplies balls to the ball mill at any frequency according to an electrical signal command, and accumulates the power consumption of the motor that drives the ball mill within a unit time and distributes the latest cumulative power consumption with the previous cumulative power consumption per unit time Comparing, thereby giving the operation and instruction device for adjusting the frequency of supplementary ball realized by the above-mentioned mechanical device so that the latest accumulated value does not exceed the specified deviation range. The automatic ball feeding equipment can keep the number of balls in the ball mill at a certain level, and make the particle size distribution of the pulverized material meet the required proper particle size distribution by making the ball diameter distribution of the ball mill meet a certain requirement.

Description

Automatic ball supply device of ball mill

The invention relates to an automatic ball supply device (device) for a ball mill, in particular to an automatic ball supply device suitable for a ball mill for crushing coal when preparing a coal-water mixture (CWM) or a coal-oil mixture (COM).

The balls in the mill wear with the passage of time and, in order to obtain a product of a given particle size, it is necessary to supplement the balls in the mill by the amount of wear.

In the mine sector, the replenishment of balls is also related to the type of mineral to be ground and the grinding capacity of the mill, and for example, when 1 to 2 balls are thrown into the mill every week using a crane, it is preferable to frequently replenish balls in order to obtain a product having a stable particle size because the particle size of the product varies before and after replenishment.

In particular, in the preparation of a coal-water mixture (CWM) or a coal-oil mixture (COM), not only is it sufficient to pulverize coal into fine powder having a particle size of not more than a certain size, but it is also desirable to make the particle size distribution thereof as satisfactory as possible, and therefore, a device (means) capable of constantly supplying balls to a mill is indispensable.

In addition, in the production of high-quality ceramics, the particle size of the raw material must be strictly controlled.

The power consumption of the motor for driving the ball mill is an index for judging the loading state of the ball mill. However, during operation of the ball mill, the size and the supply state of the pulverized material, the discharge state of the pulverized material, the rotation state of the balls and the pulverized material, and the like are not always constant, and the magnitude of the power consumption of the motor for driving the ball mill is often changed due to such occasional variation factors. If the balls are replenished by using the instantaneous value of the power consumption as an index, the result is that the amount of replenishing the balls is sometimes excessive and sometimes insufficient, and it is difficult to adjust the balls in the mill to a level at which the amount is always constant.

Therefore, the first problem to be solved is to set an index and a ball-replenishing device that can always maintain a certain number of balls in the mill for frequent ball replenishment.

Next, as described above, in order to obtain a stable coal-water mixture (CWM), it is necessary to experimentally determine an appropriate value of the particle size distribution of finely pulverized coals of different types, and in order to obtain such an appropriate particle size distribution of the coals, it is necessary to experimentally determine a specific spherical diameter distribution to be provided to the balls in the mill depending on the types of the coals.

When only the balls having the largest diameter used in the mill are supplied to the mill, the balls gradually wear after a long period of operation, and balls having various diameters are present in the mill from the newly supplied balls having the largest diameter to the balls having a very small diameter to be discharged. However, such a naturally occurring distribution of the spherical diameters is not necessarily the most suitable spherical diameter distribution required for obtaining a proper particle size distribution of the coal, and it is sometimes necessary to add the spheres having the largest diameters and to separately supply some spheres having medium diameters. The same is true for high-quality ceramic raw materials.

The second problem to be solved is therefore to set the index and the feeding means for the medium-diameter balls that are frequently fed, in order to obtain the most suitable ball size distribution required to obtain a suitable particle size distribution of the coal or high-quality ceramic raw material.

The present invention has an object to provide an automatic ball supply apparatus for a ball mill capable of solving the above problems.

The automatic ball supply device of the ball mill of the invention is provided with the following devices: the ball supply device comprises a mechanical device for supplying balls into the mill at an arbitrary frequency (frequency) according to an electric signal command, and an arithmetic-command device for calculating the power consumption of a motor for driving the ball mill in a unit time in an accumulated manner, comparing the latest accumulated power consumption with the distribution of the accumulated power consumption of the motor for driving the ball mill in the previous unit time, and giving an electric signal command for adjusting the ball supply frequency realized by the mechanical device so that the latest accumulated value does not exceed a predetermined deviation range.

The invention has the following effects:

(1) the number of balls in the mill can be kept at a certain level.

(2) The particle size distribution of the pulverized material can be adjusted to a desired suitable particle size distribution by adjusting the ball diameter distribution in the mill to the desired ball diameter distribution.

(3) It is particularly effective for producing fine coal powder for producing a coal-water mixture (CWM) or a coal-oil mixture (COM) and for producing fine powder of a high-quality ceramic raw material.

Fig. 1 is a schematic view illustrating an embodiment of the present invention, fig. 2 is a schematic view illustrating another embodiment, and fig. 3 and 4 are schematic views illustrating an example of a mechanical apparatus capable of feeding two or more balls having different sizes at arbitrary frequencies, respectively.

In the figure, 1: 21A, 21B: funnel, 22A, 22B: rotary feeder, 23A, 23B: 24A, 24B: stepping motor, 31: a motor for driving the ball mill, 32: operation-instruction device, 41: automatic particle size distribution measuring apparatus 42: operation-instruction device, 5: ball, 6: a collecting discharge pipe, 7:

rotary drum

71A, 71B, 71C: pits, 8A, 8B, 8C, funnels, 81A (81B, 81C):

baffle

82A, 82B: a separator, 9: a common discharge pipe.

The details will be described below. Fig. 1 shows an example of a mechanical apparatus capable of supplying balls into a mill at an arbitrary frequency in response to an electric signal command, in which a hopper 21A, a rotary feeder 22A, and a discharge pipe 23A are provided in a ball mill 1. The balls are loaded into the hopper 21A, and the balls are discharged from the rotary feeder 22A at a frequency in accordance with an electric signal command given to the stepping motor 24A every time the rotary feeder 22A is rotated by one unit by the stepping motor 24A, and supplied to the ball mill 1 through the discharge pipe 23A.

In addition, an arithmetic and command device 32 is connected to the motor 31 for driving the ball mill, which can cumulatively calculate the power consumption value of the motor for driving the ball mill in unit time, and then compare the latest cumulative power consumption value with the previous cumulative power consumption value distribution of the motor for driving the ball mill in unit time, and give an electric signal command for adjusting the ball compensation frequency realized by the mechanical device so that the latest cumulative value does not exceed the specified deviation range. The aforementioned mechanical devices act in accordance with the electrical signal commands issued thereby.

The length of unit time of the power consumption value of the motor for driving the ball mill is calculated in an accumulated manner becauseThe factors that occasionally vary the power consumption, i.e., the average time of change due to the supply state of the material to be pulverized, the discharge state of the material to be pulverized, the rotation state of the ball and the material to be pulverized, and the like during operation of the ball mill, and the size and type of the material to be pulverized, are different from each other and are in the range of about 1 to 10 minutes (1 to 10 minutes)Wei), can be determined through experiments.

In this way, the accumulated power consumption value per unit time after the influence of the accidental variation factor is eliminated can be measured by using the microcomputer, and the latest accumulated value is compared with the accumulated power consumption value distribution of the motor driving the ball mill per unit time in the front, and the accumulated power consumption value distribution is used as an operation and command device for giving an electric signal command for adjusting the ball supply frequency realized by the mechanical device so that the latest accumulated value is limited within the specified deviation range.

When only one series of mechanical devices is provided which can replenish the balls into the mill at any frequency, the size of the replenished balls must be the largest ball diameter used in the mill. By using the provided equipment, the number of balls in the mill is always maintained at a certain level, but the distribution of the ball diameter size is naturally formed as the balls wear.

As described above, since the naturally occurring ball diameter distribution is not necessarily the optimum ball diameter distribution for obtaining the optimum particle size distribution of the coal, when the ball diameter distribution needs to be adjusted more finely, the hopper 21B, the rotary feeder 22B, and the discharge pipe 23B shown in fig. 2 should be added to the apparatus shown in fig. 1 as a second mechanical device capable of supplying balls smaller than the balls having the largest diameter used in the ball mill into the mill at an arbitrary frequency in accordance with a second electric signal command. Thus, the balls having a smaller diameter than the maximum diameter can be supplied into the mill through the collecting/discharging pipe 6 together with the balls having the maximum diameter fed by the first mechanism (the hopper 21A, the rotary feeder 22A, and the discharging pipe 23A).

The apparatus further comprises an automatic online particle size distribution measuring device 41 for measuring the particle size distribution of the pulverized material pulverized by the ball mill, and a second arithmetic/command device 42 for comparing the particle size distribution of the pulverized material of the ball mill measured by the automatic online particle size distribution measuring device with a desired particle size distribution and giving a second electric signal command for adjusting the ball-compensating frequency of the second mechanical device in accordance with the deviation from the desired particle size distribution, whereby the second mechanical device can be operated in accordance with the second electric signal command given therefrom.

The second arithmetic and instruction unit 42 will be described in further detail below. The present state of the ball diameter distribution in the mill is estimated from the particle size distribution of the pulverized material of the ball mill measured by an on-line automatic particle size distribution measuring device, and the deviation between the ball diameter distribution and the optimum ball diameter distribution which gives the required appropriate particle size distribution of the pulverized material is calculated, and a second electric signal command which can adjust the replenishment frequency of a ball having a diameter smaller than that of the largest ball by a second mechanical device is given based on the deviation value.

If necessary, a third or fourth mechanical device capable of supplying balls having different diameters into the mill at an arbitrary frequency may be further provided, and these mechanical devices may be operated in accordance with an electric signal command given by the second arithmetic/command device.

In order to supply balls of different sizes, fig. 2 shows a case where two series of a first mechanical device including the hopper 21A, the rotary feeder 22A, and the discharge pipe 23A and a second mechanical device including the hopper 21B, the rotary feeder 22B, and the discharge pipe 23B are provided, respectively.

An example of such a structure is described below with reference to fig. 3 and 4. Fig. 3 shows the situation from above, and fig. 4 shows a cross-sectional view along the line X-X. A plurality of rows of pockets (71A, 71B, and 71C depending on the size of the balls) having a size allowing the balls to enter are formed in the rotary drum 70 (i.e., a structure in which the rotary parts of a plurality of conventional rotary feeders are combined) in the axial direction, and the

pockets

8A, 8B, and 8C for the balls having various sizes are formed in the same circumference, and a common discharge pipe 9 is provided below the drum.

The balls 5 stored in the hoppers, as the drum rotates, drop one by one into the corresponding pits, and then, as the drum rotates, fall into a common discharge duct 9 connected to the ball mill and feed into the ball mill.

To supply balls of different sizes to the mill at an arbitrary frequency, a shutter 81A (81B, 81C) is provided at the outlet of each hopper, and each shutter can be opened and closed according to an electric signal command.

Further, by making the size of the dimples on the rotary drum equal to the size of the largest balls, and moving the positions of the

partitions

82A and 82B between the

hoppers

8A, 8B, and 8C, the replenishment ratio of the balls of various sizes can be changed, and the total replenishment amount can be changed by controlling the rotation speed of the drum.

The function of the apparatus of the present invention has been clarified by the foregoing description of the specific construction. That is, the present apparatus may cumulatively calculate the power consumption value of the motor for driving the ball mill per unit time, compare the latest cumulative power consumption value with the previous cumulative power consumption value distribution of the motor for driving the ball mill per unit time, and regulate the ball-replenishing frequency to limit the latest cumulative value within a predetermined deviation range, thereby performing ball-replenishing so as to maintain the number of balls in the mill at a certain level without being affected by the occasional load change in the mill.

Further, the present apparatus can measure the particle size distribution of the pulverized material pulverized by the ball mill, compare it with the desired particle size distribution, and make the distribution of the spherical diameters in the mill coincide with the desired distribution of the spherical diameters by replenishing balls smaller than the ball having the largest diameter used in the ball mill into the mill based on the deviation from the desired particle size distribution, thereby making the particle size distribution of the pulverized material a desired appropriate value.

Claims

1. Automatic ball feeding equipment for a ball mill, comprising a mechanical device capable of feeding balls into the mill at any frequency in accordance with electrical signal instructions, and a computing and commanding device capable of accumulating and calculating the power consumption value of the motor driving the ball mill per unit time, and comparing the latest accumulated power consumption value with the distribution of the accumulated power consumption values of the motor driving the ball mill per previous unit time, thereby providing an electrical signal instruction for adjusting the frequency of ball feeding achieved by the mechanical device so that the latest accumulated value does not exceed a specified deviation range.

2. The automatic ball supply device for a ball mill according to claim 1, wherein the balls supplied are the balls with the largest diameter used in the ball mill.

3. The automatic ball feeding device for a ball mill as described in claim 2 comprises a second mechanical device capable of feeding balls smaller than the largest diameter balls used in the ball mill into the mill at an arbitrary frequency according to a second electrical signal instruction, an on-line automatic particle size distribution measuring device for measuring the particle size distribution of the pulverized material pulverized by the ball mill, and a second operation and instruction device for comparing the particle size distribution of the ball mill pulverized material measured by the on-line automatic particle size distribution measuring device with the required particle size distribution and providing a second electrical signal instruction for adjusting the ball feeding frequency implemented by the second mechanical device according to the deviation from the required particle size distribution.

4. The automatic ball feeding device for a ball mill as claimed in claim 3 has a mechanical device capable of replenishing balls into the mill at any frequency according to an electrical signal instruction, and is a rotary feeder having a plurality of rows of rotating drums arranged axially, each row having recesses of a size sufficient to allow balls to enter on the same circumference.