JPH0418938A - Operating method for vertical type roller mill - Google Patents

Abstract

PURPOSE:To minimize deterioration of grinding capacity by adding water to ejected stone at the specified rate to perform humidity conditioning while ejected stone is discharged from a mill and joined to a freshly supplied raw material and properly controlling the circulating amount of ejected stone in accordance with the change in grindability of a raw material to be ground. CONSTITUTION:In the vertical type roller mills 4, 5 having an external circulation system of ejected stone, while ejected stone 7 is discharged from the mills and joined to a freshly supplied raw material 1, this ejected stone 7 is measured by a weighing equipment 15. Thereafter water is added to ejected stone in an amount of 1-5% by weight based on ejected stone 7 with a water adding device 17 and humidity conditioning is performed. As a result, the circulating amount of ejected stone is properly controlled in accordance with the change in grindability of the raw material and deterioration of grinding capacity of the mills. Thereby deterioration of grinding capacity can be minimized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention employs an external rock circulation system for pulverizing cement raw materials, blast furnace slag, coal chemicals, etc. through cooperation between a rotating pulverizing table and pulverizing rollers. The present invention relates to a method of operating a vertical roller mill.

[Prior Art] Figure 3 is a schematic diagram of a conventional vertical roller mill that employs an external rock circulation system and is equipped with a crushing table 4 and crushing rollers 5, and is widely used as a mill for crushing raw materials for cement and coal. It is being

Raw material supplied to the mill? ! The material to be crushed 41 is fed through the supply pipe 2 to the center of a disk-shaped crushing table 4 that is rotated by a drive motor 3 with a reducer installed at the bottom of a cylindrical or truncated conical mill casing. A crushing table 4 and a plurality of crushing rollers that are pressed into contact with a hydraulic or spring-type crushing roller pressure device (not shown) and driven to rotate at positions that equally divide the outer circumference of the upper surface of the crushing table 4 in the circumferential direction. 5 and is crushed. The pulverized material is dried and classified by a hot gas flow 6 blown into the mill from below the outer periphery of the pulverizing table 4, and is separated into coarse particles with a coarse particle size and relatively fine particles. The coarse particles fall while drying against the hot gas flow 6 and are discharged from the mill as waste stones 7. After that, they are transported by a transport device 14, and together with the feed material 1, they are placed on the grinding table 4 again as a material to be ground. will be put into the

On the other hand, relatively fine particles are removed from the grinding table 4 along with the gas flow.
It is transported to a sorting machine 8 located above and rotating around a vertical axis, where it undergoes a second sorting action. The fine particles that have passed through the classifier 8 are processed into a bag filter 9 installed downstream to produce a product.
Particles that are collected as O and separated without passing through the classifier 8 fall to the lower part of the mill and are guided onto the grinding table 4 again to be crushed.

Here, I would like to add a little bit about the external stone circulation system, which is that instead of returning the pulverized materials that fall from around the pulverizing table 4 onto the pulverizing table 4 again using the hot gas flow 6 blown up from around the table, , after being discharged outside the mill, it is transported to the upper part of the mill by a mechanical transport device 14 and placed on the grinding table 4 again, thereby reducing the amount of gas passing through the mill and reducing the power of the exhaust fan 24. This is what I am trying to do.

[Problems to be Solved by the Invention] Vertical roller mills that employ the conventional external rock circulation system have the following problems.

In other words, in the case of a vertical roller mill with external rock circulation system,
The grindability of the raw material supplied to the mill may deteriorate, or the grinding lap 4 or the grinding roller 5 may become damaged due to long-term operation of the mill.
As wear progresses and the crushing capacity decreases, it becomes difficult to crush the material to be crushed, and the amount of circulating waste stones 7 increases, making it difficult to operate the mill.

In addition, when the amount of dry powdery waste stone increases, the vertical roller mill may generate large vibrations that may make the mill unable to operate.

In this case, operational adjustments will be made to reduce the amount of raw material supplied, but such an operating method will result in time losses such as longer time required to obtain the required amount of product, as well as power losses. This causes an increase in the cost of invitation.

The purpose of the present invention is to provide a method for appropriately controlling the circulation amount of waste stone and suppressing the decrease in the crushing capacity as much as possible in response to changes in the pulverizability of raw materials and decreases in the crushing capacity of the mill. be.

[Measures for solving the problem 1'U] In order to solve the above-mentioned problems, while the waste rock circulates outside the mill through the transport device, the weight of the waste rock that is weighed is Water is humidified and adjusted to a range of 1% to 5%, and mixed during transportation.

It is placed on the grinding table as a material to be ground together with new raw materials.

As mentioned above, the waste rock contains hard-to-pulverize materials that cannot be taken out of the mill system as a product, although they have already been subjected to the crushing action at least once by the crushing table and the crushing rollers. In addition, since the size is smaller, if the rice is fed into the mill again, it may not fall onto the grinding table and may get carried away by the hot gas flow, so it is difficult to prevent it from falling between the grinding table and the grinding rollers again. It is in a state where it is difficult to get caught.

Therefore, by adding moisture to the waste stones, even if they are fed onto the grinding table again, they will be reliably caught between the grinding table and the grinding rollers, and this has led to the use of vertical roller mills for a long time. Efficient operation is possible without changing the crushing capacity of the machine.

Furthermore, the amount of water added to the waste rock varies from 1 to 5%.
If the amount of water is less than 1%, it is difficult for the waste stones to be caught between the crushing table and the crushing rollers, and the effect of the present invention will be reduced, and if it exceeds 5%, the drying cost will increase. This range was created to make it easier to control the power required for the mill and the degree of dryness of the product by changing the amount of water depending on the properties of the raw materials supplied to the mill and the properties of the waste rock, which can increase costs. .

[Example] FIG. 1 is a schematic diagram showing an embodiment of the present invention.

The raw material 1 to be supplied to the mill is passed through a material supply chamber 2 to the center of a disk-shaped grinding table 4 which is rotated by a drive motor 3 with a speed reducer installed at the bottom of a cylindrical or truncated conical mill casing. It is pressed against the grinding table 4 by centrifugal force and a hydraulic or spring-type grinding roller pressing device (not shown) that equally divides the outer periphery of the top surface of this grinding table 4 in the circumferential direction, resulting in driven rotation. It is caught between the plurality of crushing rollers 5 and crushed.

The pulverized material is dried and classified by a hot gas flow 6 blown into the mill from below the outer periphery of the pulverizing table 4, and is separated into coarse particles with a coarse particle size and relatively fine particles. The fine particles are carried along with the gas flow to a classifier 8 located above the crushing table 4 and rotating around a vertical axis, where they are subjected to a second classification action. The fine particles that have passed through the classifier 8 are collected as products 10 by the bag filter 9, which is sucked into the exhaust fan 24 installed downstream, and the particles that cannot pass through the classifier 8 and are separated fall to the bottom of the mill. , and is guided onto the grinding table 4 again to be ground.

On the other hand, the coarse particles fall while drying against the hot gas flow 6 and are discharged from the mill as waste stones 7, and are transferred to a weighing device 15 for waste stones.
After being metered in, a predetermined amount of water is added by a water addition device 17 and sent to the feedstock 1 via a waste rock transport device 14.
It is also placed on the crushing table.

In this case, the positional relationship between the waste rock measuring device 15 and the water addition device 17 may be different, but the position of the water addition device 17 is such that the waste rock is almost homogeneous before the waste rock is combined with the feed material. It is desirable to set it in a position where it can get wet.

In addition, the amount of water added should be in the range of 1 to 5% based on the critical condition of the waste rock, taking into consideration the amount of raw materials supplied, the amount of waste rock, the power required for the mill, and the drying condition of the product. Desirable 5.

FIG. 2 is a schematic diagram showing another embodiment of the invention.

The operation etc. are the same as those shown in Fig. 1, so the explanation is omitted, but in order to further enhance the effect when carrying out the present invention, this system is designed to automatically set the amount of water added. .

A raw material measuring device 13 is installed in the raw material supply device 12, and a water addition amount control device 18 is installed in the water addition device 17.

The supply amount signal from the raw material measuring device 13 passes through a filter 19, unnecessary frequency components are removed, and the signal is sent to the controller 23.
sent to.

Similarly, the signal of the amount of waste rock from the waste rock measuring device 15, the power signal of the drive motor wattmeter 16, and the signal of the amount of water added from the water addition amount control device 18 also pass through filters 20 to 22, and are sent to the controller 23. sent to.

Based on these signals, the amount of water added is calculated using a predetermined calculation formula, and the water addition amount control device 18 automatically controls water addition I according to this calculated value.

[Effects of the Invention] As described above, the present invention has the following remarkable effects in a vertical roller mill that employs the external rock circulation system.

(1) Even if the raw material supplied into the mill is very hard and difficult to crush, it can be crushed without increasing the amount of waste stone circulating.

(2) Even if the grinding table and grinding rollers are worn out due to long-term operation of the mill and the grinding capacity is reduced, the amount of waste stone circulation is appropriately controlled to minimize the decline in the grinding capacity. becomes possible.

[Brief explanation of drawings]

1 and 2 are schematic diagrams showing an embodiment of the present invention, and FIG. 3 is a schematic diagram of a vertical roller mill employing a conventional external rock circulation system. 1. Supply thick phase, 2. Materials to be crushed supply pipe, 3.
...Drive motor, 4.Crushing table, 5.Crushing roller, 6.Hot gas flow, 7.Discharge stone,
8... Classifier, 9. Bag filter, lO...
・Product, 11...Water, 12...Raw material supply device, 13...Original inclination meter 1 device, 14...Exhaust rock transport device, 15...Exhaust rock weighing device, 16...Drive motor Power meter, 17...Water addition device, 18...Water addition amount control device, 19-22...Filter, 23...
・Controller, 24...Exhaust fan. Patent applicant Ube Industries Co., Ltd.

Claims (1)

[Claims] In a vertical roller mill that has an external stone circulation system, between the time the waste stone leaves the mill and is combined with newly supplied raw materials, the weight ratio of the waste stone to the waste stone is 1% or more and 5% or less. A method of operating a vertical roller mill characterized by adding water to control humidity.