CN114007751B - Method for operating pulverizing system and method for producing powder - Google Patents

Abstract

A method for operating a pulverizing system, the pulverizing system comprising: a vertical pulverizer for pulverizing a pulverized material, a pulverized material circulation path through which a pulverized material is fed to move from a discharge port of the pulverizer to a feed port, and a classifier provided in the pulverized material circulation path and dividing the pulverized material into fine powder as a product and coarse powder returned to the pulverizer; a collector for recovering fine powder; the air pumping channel is connected to the upper part of the pulverizer; an air extraction fan for extracting air from the pulverizer to the air extraction path by setting air extraction volume; and a dust collector for separating the fine powder from the air suction of the pulverizer and conveying the fine powder to the pulverized material circulation path, wherein a correlation between the air suction volume of the pulverizer and the powder degree of the fine powder to be recovered is obtained, the air suction volume of the fine powder to be recovered is estimated based on the correlation, and the air suction volume is used as a set air suction volume.

Description

Operation method of grinding system and manufacturing method of powder

Technical field

The present invention relates to a method for producing powder obtained by pulverizing a pulverized raw material using a vertical pulverizer, and an operating method of a pulverizing system used in the method.

Background technique

Conventionally, a vertical grinder has been known as a type of grinder that performs drying and grinding of pulverized raw materials. Examples of pulverized raw materials include cement raw materials, calcium carbonate, and the like. Patent Documents 1 and 2 disclose a grinding system including such a vertical grinder.

Patent Document 1 discloses a closed-circuit crushing type crushing system. This crushing system has a vertical crusher with a built-in classifier. When the pulverized raw material is pulverized by a pulverizer, a pulverized material containing coarse powder and fine powder is produced. After the coarse powder is temporarily discharged from the pulverizer, it is supplied to the pulverizer again and used for re-pulverization. The fine powder passes through the classifier together with the gas rising in the pulverizer, and is classified into fine powder and powder other than fine powder in the classifier. The fine powder is discharged from the pulverizer together with the gas, and is collected by the dust collector before being recycled as a product. The gas separated from the fine powder in the dust collector returns to the pulverizer.

The grinding system of Patent Document 2 includes a classifier independent of the vertical grinder. The fine powder in the ground material of the pulverizer is discharged from the pulverizer together with the gas extracted from the pulverizer, and is separated from the gas by a dust collector. The gas separated from the fine powder by the dust collector returns to the pulverizer, and the fine powder is transported to the classifier through the conveyor. The coarse powder in the pulverized material of the pulverizer is conveyed to the classifier through the conveyor. The ground material transported to the classifier is classified into fine powder and powder other than fine powder. The fine powder is recycled as a product through the dust collector of the subsequent stage, and the powder other than fine powder is returned to the pulverizer. In the grinding system of Patent Document 2, the circulation system of the ground material of the grinder is independent of the circulation system of the gas of the grinder. Therefore, the air extraction volume from the grinder and the classification air volume of the classifier can be independently adjusted.

Patent Document 1: Japanese Patent Application Laid-Open No. 9-117685

Patent Document 2: Japanese Patent Application Publication No. 2018-202347

Contents of the invention

The present invention is a further development of the invention described in Patent Document 2, and its object is to provide a technology for producing fine powder (powder) with an arbitrarily adjusted powder degree using a closed-circuit grinding system including a vertical grinder. .

A method of operating a pulverizing system according to one aspect of the present invention is a method of operating a pulverizing system. The above-mentioned pulverizing system includes:

Vertical crusher, which crushes the raw materials;

A crushed material circulation path, which allows the crushed material to move from the discharge port of the above-mentioned vertical crusher to the supply port;

A classifier, which is installed in the above-mentioned pulverized material circulation path and classifies the above-mentioned pulverized material into fine powder as a product and coarse powder returned to the above-mentioned vertical grinder;

A collector that recovers the above-mentioned fine powder;

An air extraction path is connected to the upper part of the above-mentioned vertical crusher;

An exhaust fan, which exhausts air from the above-mentioned vertical grinder to the above-mentioned exhaust path at a set exhaust air volume; and

A dust collector that separates fine powder from the exhaust air of the above-mentioned vertical pulverizer and transports it to the above-mentioned pulverized material circulation path,

The above operation method of the crushing system is characterized by:

The correlation between the exhaust air volume from the vertical pulverizer and the powder degree of the fine powder to be recovered is obtained. Based on this correlation, the exhaust air volume that can obtain the desired powder degree is inferred, and the exhaust air volume is calculated as The exhaust air volume is set above.

In addition, a method for producing powder according to one aspect of the present invention includes the steps of supplying a pulverized raw material to a vertical pulverizer for pulverization, and extracting air from the vertical pulverizer at a set exhaust air volume. The fine powder in the pulverized material is brought out by riding on the air flow. The fine powder is separated from the air flow and transported to the classifier through a conveyor. The remaining part of the pulverized material is transported to the classifier through the conveyor and passes through the classifier. The above-mentioned ground material is classified into fine powder and coarse powder according to the set particle size, the above-mentioned fine powder is air-transported from the above-mentioned classifier to the collector and recovered as a product through the above-mentioned collector, and the above-mentioned coarse powder is separated from the above-mentioned classification machine. The machine is sent back to the above-mentioned vertical crusher for re-crushing. Furthermore, the above-mentioned powder manufacturing method is characterized by determining a correlation between the exhaust air volume from the above-mentioned vertical grinder and the powder degree of the above-mentioned fine powder to be recovered, and inferring that a desired powder degree can be obtained based on the correlation. The exhaust air volume shall be used as the above set exhaust air volume.

According to the operation method of the grinding system and the method of producing powder, by changing the set exhaust air volume, fine powder (powder) of any powder degree can be obtained. In other words, the degree of powder to be obtained can be changed, and a powder product corresponding to the purpose of use can be obtained. As a result, the quality of powder products can be improved.

According to the present invention, it is possible to provide a technology that uses a closed-circuit grinding system including a vertical grinder to produce fine powder (powder) with an arbitrarily adjusted powder degree.

Description of drawings

FIG. 1 is a diagram showing the overall structure of a grinding system according to an embodiment of the present invention.

FIG. 2 is a diagram showing the structure of a second experimental device that simulates a conventional crushing system.

FIG. 3 is a graph showing the correlation between the exhaust air volume from the vertical grinder and the powder degree of the recovered fine powder.

FIG. 4 is a graph showing a characteristic curve of the unit power consumption of the vertical grinder with respect to the exhaust air volume from the vertical grinder.

Detailed ways

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the overall structure of a grinding system 1 according to an embodiment of the present invention.

The closed-circuit crushing system 1 shown in FIG. 1 includes a vertical crusher 2 (hereinafter simply referred to as "crusher 2"), a crushed material circulation system 3 connected to the crusher 2, and a gas circulation system connected to the crusher 2. 4.

〔Vertical crusher 2〕

The grinder 2 includes a casing 21 that forms a grinding chamber 20 for grinding raw materials. In the casing 21, a rotary table 22 rotating around a vertical rotation axis and a plurality of grinding rollers 23 are provided. The plurality of grinding rollers 23 are pressed against the rotary table 22 by a pressure mechanism (not shown) to perform driven rotation. . Below the casing 21, a mill motor 24 as a rotational drive source of the turntable 22 and a speed reduction mechanism 25 that transmits the rotational power of the mill motor 24 to the turntable 22 are provided. Pulverizer 2 does not have a built-in classifier.

A supply port 26 is provided in the upper part of the housing 21 . The pulverized raw material is introduced to the upper surface of the rotary table 22 through the supply port 26 . In addition, an air extraction port 27 is provided above the turntable 22 and in the upper portion of the housing 21 . Through the air extraction port 27, the fine powder generated by the grinding of the ground raw materials is discharged by riding on the blown air flow. A discharge port 28 is provided below the turntable 22 . The pulverized material overflowing from the outer peripheral edge of the rotary table 22 is discharged to the outside of the pulverizer 2 through the discharge port 28 . In addition, a hot air outlet 29 is provided around the outer periphery of the turntable 22 . Hot air is blown upward from the hot air outlet 29 into the grinding chamber 20 .

[Pulverized material circulation system 3]

The ground material circulation system 3 is configured to separate fine powder as a product from the ground material discharged from the discharge port 28 of the grinder 2 and to return the ground material from which the fine powder has been separated to the grinder 2 . The fine powder separated by the crushed material circulation system 3 is recovered as a product.

The ground material circulation system 3 has a ground material circulation path 30 in which the ground material discharged from the grinder 2 moves from the discharge port 28 of the grinder 2 to the supply port 26 . The classifier 7 is provided in the crushed material circulation path 30 . In addition, in the present embodiment, since the ground material inlet 71 of the classifier 7 is located above the discharge port 28 of the crusher 2, the conveyor 31 conveys the ground material upward from the discharge port 28 to the ground material inlet 71. It is provided in the crushed material circulation path 30. The conveyor 31 of this embodiment is a bucket elevator provided with a plurality of buckets (not shown).

The discharge port 28 of the crusher 2 is connected to the first inlet 31a of the conveyor 31 via the passage 30a. The conveyor 31 conveys the crushed material input through the first inlet 31a and the second inlet 31b described below upward, and discharges it from the outlet 31c. The outlet 31c of the conveyor 31 is connected to the crushed material inlet 71 of the classifier 7 via the passage 30b. In addition, a distribution damper (not shown) may be provided in the passage 30b connecting the conveyor 31 and the classifier 7 . Furthermore, the distribution damper may be used to transport part of the pulverized material directly to the supply port 26 of the pulverizer 2 without passing through the classifier 7 .

The classifier 7 classifies the supplied ground material into fine powder and coarse powder according to the set particle diameter. In addition, the set particle size of "fine powder" is determined based on the particle size of the product to be recovered. The "coarse powder" here means the pulverized material supplied to the classifier 7 which has a particle diameter larger than that of fine powder. In this embodiment, an air flow classifier is used as the classifier 7 . However, the classifier 7 is not limited to an air flow classifier as long as it can classify the pulverized material into fine powder and powder other than fine powder according to the particle size.

The ground material classified into coarse powder by the classifier 7 is discharged from the discharge port 72 . The discharge port 72 is connected to the supply port 26 of the grinder 2 via the passage 30c.

The ground material classified into fine powder by the classifier 7 rides on the air flow and is discharged from the exhaust port 73 . The exhaust port 73 is connected to the inlet of the collector 6 via the passage 64 . A classification fan 66 is provided in the exhaust passage 65 of the collector 6 . The exhaust air volume of the classification fan 66 is adjusted so that it becomes a predetermined classification air volume F2.

The collector 6 collects fine powder accompanying the gas discharged from the classifier 7 and separates the fine powder from the gas. In this embodiment, a bag filter is used as the collector 6 . However, it is sufficient that the collector 6 can capture fine powder accompanied by gas, and is not limited to a bag filter.

[Gas circulation system 4]

The gas circulation system 4 is configured to separate the fine powder from the exhaust gas of the pulverizer 2 and return the gas from which the fine powder is separated to the pulverizer 2 as hot air.

The gas circulation system 4 has a gas circulation path 40 that allows gas extracted from the grinder 2 to flow from the exhaust port 27 of the grinder 2 to the hot air inlet 29a. The gas circulation path 40 is provided with a dust collector 41 that separates fine powder from the exhaust air from the pulverizer 2 , an exhaust fan 42 , and a hot air supply source 43 that supplies hot air to the gas circulation path 40 . The exhaust air volume of the exhaust fan 42 is adjusted so that it becomes the exhaust air volume F1.

The air extraction port 27 of the pulverizer 2 is connected to the inlet of the dust collector 41 via the air extraction path 40a. The outlet of the dust collector 41 is connected to the hot air inlet 29a of the grinder 2 via the passage 40b. The hot air supply source 43 is connected to the passage 40b.

The dust collector 41 separates fine powder from the exhaust air from the pulverizer 2 (hereinafter referred to as "mill exhaust gas"). In this embodiment, a cyclone dust collector using the suction action of the exhaust fan 42 is used as the dust collector 41 . However, the dust collector 41 is not limited to a cyclone dust collector as long as it can separate fine powder from the mill exhaust gas.

The fine powder outlet of the dust collector 41 is connected to the second inlet 31b of the conveyor 31 via the fine powder conveyance path 88 . The fine powder separated from the mill exhaust gas by the dust collector 41 is conveyed to the conveyor 31 through the conveyance path 88 .

In the passage 40b connected to the outlet of the dust collector 41, a passage 84 for conveying the mill exhaust gas in the passage 40b to the classifier 7 is connected downstream of the exhaust fan 42 in the mill exhaust flow. This passage 84 is provided with a flow rate adjustment device 85 that adjusts the flow rate of the mill exhaust gas flowing to the classifier 7 . By changing the opening degree of the flow rate adjusting device 85 , the flow rate of the mill exhaust gas flowing to the classifier 7 can be adjusted. As a result, the flow rate of the mill exhaust gas returned to the pulverizer 2 can be adjusted. The flow rate adjustment device 85 may have any form as long as it is a mechanism that adjusts the flow rate of the mill exhaust gas flowing to the classifier 7 , and may be at least one of a damper, a flow rate adjustment valve, and a fan, for example.

The hot air supply source 43 may be, for example, a hot air generating furnace that generates hot air at a desired temperature. The hot air supplied from the hot air supply source 43 to the gas circulation path 40 is transported to the hot air inlet 29a of the grinder 2 through the passage 40b together with the mill exhaust gas. However, the hot air supply source 43 is not limited to the hot air generating furnace. For example, when there is a high-temperature gas generating source such as a baking furnace (cement baking furnace) around the crusher 2, the high-temperature gas generating source may also be used. It is the hot air supply source 43.

[Method for producing powder using grinding system 1]

Here, a method of operating the pulverizing system 1 configured as above and a method of producing powder using the pulverizing system 1 will be described. In the grinder 2 , the hot air blown out from the hot air outlet 29 preheats the inside of the grinding chamber 20 including the rotary table 22 and the grinding roller 23 . Furthermore, the turntable 22 is driven and rotated by the mill motor 24, and the peripheral surface is driven and rotated by the plurality of grinding rollers 23 pressed against the grinding surface (upper surface) of the turntable 22. The pulverized raw material is supplied to the rotary table 22 rotated in this way through the supply port 26 . The pulverized raw material is pulverized between the rotary table 22 and the pulverizing roller 23 . The coarse powder in the crushed material overflows from the periphery of the rotary table 22 and is discharged out of the machine through the discharge port 28 . In addition, the fine powder in the pulverized material is discharged from the air extraction port 27 by riding on the blown air flow.

The mill exhaust gas coming out of the air extraction port 27 of the pulverizer 2 flows into the dust collector 41 . In the dust collector 41, the fine powder accompanying the mill exhaust gas is separated from the mill exhaust gas. The separated fine powder is conveyed to the second inlet 31b of the conveyor 31 through the conveyor path 88, and merges with the flow of the ground material in the ground material circulation system 3.

On the other hand, the mill exhaust gas separated into fine powder by the dust collector 41 exits the dust collector 41 , is sucked in by the exhaust fan 42 , and is sent to the downstream passage 40 b of the gas circulation system 4 . Here, the opening degree of the flow rate adjusting device 85 is adjusted in order to balance the flow rate of the mill exhaust gas flowing into the passage 40 b by the suction action of the exhaust fan 42 and the flow rate of the mill exhaust gas returned to the pulverizer 2 . The hot air supplied from the hot air supply source 43 to the passage 40b flows into the grinder 2 together with the mill exhaust gas, and is blown out into the mill from the hot air outlet 29 .

The crushed material discharged from the discharge port 28 of the crusher 2 is conveyed upward by the conveyor 31 and flows into the classifier 7 . In the classifier 7, the pulverized material is classified, and fine powder is separated from the pulverized material. The ground material after the fine powder is separated by the classifier 7 is discharged from the classifier 7 and transported to the supply port 26 of the grinder 2 through the passage 30c, and is crushed again by the grinder 2. The fine powder separated from the ground material by the classifier 7 is discharged from the exhaust port 73 of the classifier 7 along with the gas, and is air-flow transported to the collector 6 through the passage 64 . In the collecting machine 6, the fine powder is collected. The fine powder is recycled as a product, for example bagged. On the other hand, the gas separated from the fine powder by the collector 6 flows out into the exhaust passage 65 and is released into the atmosphere.

[Powder degree adjustment]

The degree of powderiness (the fineness of particles) of the fine powder recovered as a product as described above is one of the important factors indicating the quality of the fine powder. In the grinding system 1 having the above structure, the degree of powderiness of the fine powder to be obtained can be changed by adjusting the exhaust air volume F1. In order to verify that the degree of fine powder can be adjusted by adjusting the exhaust air volume F1, the following verification experiment was performed.

In the verification experiment, the first experimental device 101 simulating the grinding system 1 of the present embodiment and the second experimental device 101 simulating the existing grinding system were used (see FIG. 2 ).

The first experimental device simulates the crushing system 1 shown in Fig. 1, and detailed explanation is omitted. The experiments of Examples 1 to 4 were conducted using the first experimental device. Table 1 shows the experimental conditions of Examples 1 to 4 and Comparative Example 1. In Examples 1 to 4, the classification air volume F2 was kept constant at 15 [m ³ /min]. In Example 1, the exhaust air volume F1 is set to 0 [m ³ /min]. In Example 2, the exhaust air volume F1 is set to 3 [m ³ /min]. In Example 3, the exhaust air volume F1 is set to 0 [m 3 /min]. Let it be 6 [m ³ /min]. In Example 4, the exhaust air volume F1 is set to 9 [m ³ /min]. In addition, the exhaust air volume F1 is the exhaust air volume of the exhaust fan 42 , and the grading air volume F2 is the exhaust air volume of the grading fan 66 .

FIG. 2 is a diagram showing the structure of the second experimental device 101. The second experimental device 101 includes a vertical grinder 102 , a collector 106 connected to the exhaust port 127 of the grinder 102 , and a classification fan 166 that sucks the exhaust of the grinder 102 into the collector 106 . The grinder 102 includes a casing 121 forming a grinding chamber 120, a rotary table 122 that rotates around a vertical rotation axis, and a plurality of grinding rollers 123 that are press-contacted with the rotary table 122 and driven to rotate by a pressurizing mechanism (not shown). , the mill motor 124 as the rotational driving source of the turntable 122 , the reduction mechanism 125 that transmits the rotational power of the mill motor 124 to the turntable 122 , and the classifier 107 provided above the grinding roller 123 in the casing 121 .

In the pulverizer 102 , the pulverized raw material supplied to the rotating rotary table 122 is pulverized between the rotary table 22 and the grinding roller 23 while being dried by hot air. The fine powder in the pulverized material is transported to the classifier 107 by riding on the air flow blown from below, and is classified by the classifier 107 into fine powder and powder other than fine powder. The fine powder rides on the air flow and is discharged from the exhaust port 127, and is recovered by the collector 106. The fine powder classified into fine powder other than fine powder by the classifier 107 and the coarse powder overflowing from the periphery of the rotary table 122 are temporarily discharged outside the machine, and are supplied to the pulverizer 102 again together with new pulverized raw materials.

The experiment of Comparative Example 1 was conducted using the second experimental device 101 having the above-mentioned structure. In Comparative Example 1, the classification air volume F2 was kept constant at 15 [m ³ /min]. In addition, the classified air volume F2 is the air volume of the classified fan 166 . In the second experimental device 101, since the exhaust air volume (exhaust air volume) from the pulverizer 102 is directly affected by the classified air volume F2, it is difficult to adjust only the exhaust air volume.

[Table 1]

<Experimental conditions>

Example 1 Example 2 Example 3 Example 4 Comparative example 1 experimental device First First First First second Exhaust air volume F1[m ³ /min] 0 3 6 9 Classified air volume F2 [m ³ /min] 15 15 15 15 15

In the experiments of Examples 1 to 4 and Comparative Example 1, the grinding raw materials were put into the mill of the experimental device and the fine powder was recovered. In order to determine the powderiness of the recovered fine powder samples, a specific surface area test and a mesh sieve test were conducted based on JIS R 5201 (Physical Test Methods for Cement). In the specific surface area test, the Blaine specific surface area [cm ² /g] of the sample is measured using a specific surface area tester (Bryan air permeability measuring device). In the sieve test, a test sieve with a mesh size of 45 μm is used to sieve the sample, and the residual amount on the sieve is weighed to calculate the residual amount [%] of the sample on the sieve (hereinafter, the particle size is 45 μm). The content of the above particles is called "45μR").

FIG. 3 is a graph showing the correlation between the exhaust air volume F1 from the pulverizer 2 and the powder degree of the recovered fine powder. The vertical axis of the graph represents the specific surface area [cm ² /g], the horizontal axis represents 45 μR [%], and the results of the powderiness test of the fine powders obtained in Examples 1 to 4 and Comparative Example 1 are indicated. Common to Examples 1 to 4 and Comparative Example 1, under constant exhaust air volume F1, the specific surface area decreases as the value of 45 μR increases. In addition, at a constant 45 μR, as the exhaust air volume F1 becomes larger, the specific surface area becomes smaller.

The value of the specific surface area is affected by the amount of fine powder in the fine powder. When 45 μR is a constant value, the specific surface area decreases as the exhaust air volume F1 increases. It can be seen that as the exhaust air volume F1 increases, the amount of fine powder decreases, resulting in a distinct powdery structure with a narrow distribution width. . In other words, it is found that the powderiness (specific surface area) of the fine powder can be adjusted by adjusting the exhaust air volume F1.

In addition, regarding Examples 1 to 4 and Comparative Example 1, the electric power consumption rate consumed in the production of fine powder was measured. As the unit power consumption, the unit power consumption of the grinder motors 24 and 124 was measured. The unit power consumption of the mill motors 24 and 124 accounts for most of the unit power consumption consumed in the production of fine powder.

4 is a graph showing a characteristic curve of the unit power consumption of the pulverizer 2 relative to the exhaust air volume F1 from the pulverizer 2 in the production of fine powder in Examples 1 to 4 and Comparative Example 1. The vertical axis of the graph represents the ratio of the unit power consumption [kWh/t (DB)] of Examples 1 to 4 when the unit power consumption [kWh/t (DB)] of Comparative Example 1 is set to 100%. The vertical axis represents the exhaust air volume F1 [m ³ /min].

The unit power consumption of Examples 1 to 4 are all lower than that of Comparative Example 1. In addition, if the extraction air volume F1 is less than about 4.5m ³ /min, the unit power consumption will ^gradually decrease as the extraction air volume F1 increases. As the air volume F1 increases, the unit power consumption gradually increases. Especially in the range of the extraction air volume F1 of about 2 to 6 m ³ /min, the unit power consumption is reduced by about 30% compared with the comparative example, and the power reduction effect is significant. It is presumed that this is because excessive grinding is suppressed by extracting the fine powder portion from the grinder 2 together with the air, and therefore the unit power consumption is reduced. From the viewpoint of such a reduction in unit power consumption, it is clear that there is a preferable range for the exhaust air volume F1.

Based on the results of the above verification experiment, it was verified that the powderiness (specific surface area) of the fine powder can be adjusted by adjusting the exhaust air volume F1 from the pulverizer 2 . In addition, it was verified that by adjusting the exhaust air volume F1 from the grinder 2, the unit power consumption of the grinder motor 24 can be reduced by preventing over-grinding.

In the operation method of the grinding system 1 of this embodiment, the powder degree of the fine powder is adjusted using the proven principle. That is, the operation method of the grinding system 1 of this embodiment is an operation method of the grinding system. The grinding system includes: a grinding machine 2 that grinds the grinding raw material; and a grinding material circulation path 30 that supplies the grinding material from the grinding machine 2 The discharge port 28 moves to the supply port 26; the classifier 7 is installed in the pulverized material circulation path 30, and divides the pulverized material into fine powder as a product and coarse powder returned to the pulverizer 2; a collector 6, which Recover fine powder; an air extraction path 40a, which is connected to the upper part of the pulverizer 2; an exhaust fan 42, which exhausts air from the pulverizer 2 to the air extraction path 40a with a set exhaust air volume; and a dust collector 41, which The fine powder is separated from the exhaust air of the pulverizer 2 and transported to the pulverized material circulation path 30. The correlation between the exhaust air volume from the pulverizer 2 and the powder degree of the recovered fine powder is obtained (see Fig. 3). Based on this The correlation is used to infer the exhaust air volume that can obtain the desired powder degree, and this exhaust air volume F1 is used as the set exhaust air volume.

In addition, the method for producing powder using the grinding system 1 of the present embodiment includes the following: grinding the grinding raw material with the grinding machine 2 and extracting air from the grinding machine 2 at a set exhaust air volume to grind the ground material into the powder. The fine powder is brought out by riding on the air flow. The fine powder is separated from the air extraction of the pulverizer 2 and transported to the classifier 7. The remaining part of the pulverized material is transported from the pulverizer 2 to the classifier 7, and the pulverized material is passed through the classifier 7. The fine powder is classified into fine powder and coarse powder according to the set particle size, the fine powder is recovered as a product, and the coarse powder is sent back from the classifier 7 to the pulverizer 2 for re-pulverization. Furthermore, the correlation between the exhaust air volume from the pulverizer 2 and the powder degree of the recovered fine powder is obtained (see FIG. 3), and based on this correlation, the exhaust air volume that can obtain the desired powder degree is estimated, and the exhaust air volume is calculated. The air volume is used as the set extraction air volume.

According to the above-described powder manufacturing method, fine powder (powder) of any powder degree can be obtained by changing the set exhaust air volume. In other words, the degree of powderiness of the obtained fine powder can be changed to obtain a powder product corresponding to the purpose of use. As a result, the quality of powder products can be improved.

In addition, in the operation method of the grinding system 1 and the manufacturing method of the powder according to the present embodiment, a characteristic curve (see FIG. 4 ) of the unit power consumption of the grinder 2 with respect to the exhaust air volume is obtained, and based on the characteristic curve, The exhaust air volume with the smallest unit power consumption among the exhaust air volumes that can obtain the desired powder degree is used as the set exhaust air volume.

Accordingly, in addition to improving the quality of the fine powder (powder), it is also possible to reduce the unit power consumption consumed in producing the fine powder (powder).

Hereinafter, application examples of the powder manufacturing method of this embodiment will be described.

When the pulverized raw material is a cement type containing a large amount of mixture such as limestone, limestone is softer than clinker, so fine powder is easily generated, and the specific surface area of the fine powder may be higher than the value specified as a cement raw material. trend. In such a case, by increasing the exhaust air volume F1, it is possible to reduce the specific surface area of the fine powder to a predetermined value while maintaining the 45 μR of the fine powder at a predetermined value. As a result, the quality of cement raw materials can be improved.

In addition, when the pulverized raw material is a cement material with a relatively small mixture (Portland cement, etc.) such as limestone, the specific surface area of the fine powder tends to be lower than the value specified as the cement raw material. In such a case, by reducing the exhaust air volume F1, it is possible to increase the value of the specific surface area of the fine powder within a predetermined value while maintaining the 45 μR of the fine powder at a predetermined value. As a result, the quality of cement raw materials can be improved.

In the above, there is a range for the exhaust air volume F1 within the range in which the value of the specific surface area of the fine powder is a predetermined value. Therefore, if the characteristic curve of the unit power consumption versus the extraction air volume F1 is used (see Figure 4), and the extraction air volume with the smallest unit power consumption among the extraction air volumes F1 that can obtain the desired powder degree is used, then In addition to improving the quality of cement raw materials, unit power consumption can also be reduced.

Explanation of reference signs

1...crushing system; 2...vertical crusher; 3...crushed material circulation system; 4...gas circulation system; 6...collector; 7...classifier; 20...pulverizing chamber; 21...casing; 22...rotating table ; 23...crushing roller; 24...mill motor; 25...reduction mechanism; 26...supply port; 27...exhaust port; 28...discharge port; 29...hot air blowing outlet; 29a...hot air inlet; 30...pulverized material circulation path ; 30a, 30b, 30c...passage; 31...conveyor; 31a...first entrance; 31b...second entrance; 31c...outlet; 40...gas circulation path; 40a...gas extraction path; 40b...passage; 41...dust collection machine; 42...exhaust fan; 43...hot air supply source; 64...passage; 65...exhaust path; 66...exhaust fan; 71...pulverized material inlet; 72...discharge outlet; 73...exhaust outlet; 84...passage; 85 ...flow adjustment device; 88...conveyor path; 101...second experimental device; 102...vertical crusher; 106...collector; 107...classifier; 120...crushing chamber; 121...casing; 122...rotating table; 123...crushing roller; 124...mill motor; 125...reduction mechanism; 127...exhaust port; 166...exhaust fan.

Claims (4)

1. An operation method of a crushing system, the crushing system having: Vertical crusher, which crushes the raw materials; A crushed material circulation path, which allows the crushed material to move from the discharge port of the vertical crusher to the supply port; A classifier, which is installed in the pulverized material circulation path and classifies the pulverized material into fine powder as a product and coarse powder returned to the vertical pulverizer; A collector that recovers the fine powder; An air extraction path is connected to the upper part of the vertical crusher; An exhaust fan, which exhausts air from the vertical grinder to the air exhaust path at a set exhaust air volume; and A dust collector that separates fine powder from the exhaust air of the vertical pulverizer and transports it to the pulverized material circulation path, The operating method of the crushing system is characterized by: The correlation between the specific surface area of the fine powder to be recovered and the residual amount of the sieve with a predetermined mesh when the exhaust air volume from the vertical pulverizer is changed is determined, and the above-mentioned fine powder is inferred based on the correlation. The exhaust air volume at which the residual amount of the sieve is maintained at a prescribed value and the specific surface area is within a prescribed range is used as the set exhaust air volume. 2. The operation method of the crushing system according to claim 1, characterized in that: A characteristic curve of the unit power consumption of the vertical crusher relative to the exhaust air volume is obtained, and based on the characteristic curve, the residual amount of the sieve is maintained at a prescribed value and the specific surface area is within a prescribed range. Among the exhaust air volumes, the exhaust air volume with the smallest unit power consumption is used as the set exhaust air volume. 3. A method for manufacturing powder, including the following steps: The pulverized raw materials are pulverized by a vertical pulverizer, and air is extracted from the vertical pulverizer at a set exhaust air volume to bring out the fine powder in the pulverized material by riding on the air flow, and the fine powder is removed from the vertical pulverizer. The air of the vertical pulverizer is separated and transported to the classifier. The remaining part of the pulverized material is transported from the vertical pulverizer to the classifier. The classifier classifies the pulverized material according to the set particle size. Classify into fine powder and coarse powder, recover the fine powder as a product, return the coarse powder from the classifier to the vertical crusher for re-crushing, The powder manufacturing method is characterized by: The correlation between the specific surface area of the fine powder to be recovered and the residual amount of the sieve with a predetermined mesh when the exhaust air volume from the vertical pulverizer is changed is determined, and the above-mentioned fine powder is inferred based on the correlation. The exhaust air volume at which the residual amount of the sieve is maintained at a prescribed value and the specific surface area is within a prescribed range is used as the set exhaust air volume. 4. The method for producing powder according to claim 3, characterized in that: A characteristic curve of the unit power consumption of the vertical crusher relative to the exhaust air volume is obtained, and based on the characteristic curve, the residual amount of the sieve is maintained at a prescribed value and the specific surface area is within a prescribed range. Among the exhaust air volumes, the exhaust air volume with the smallest unit power consumption is used as the set exhaust air volume.