Method of operating grinding system, and grinding system

Abstract

To easily convey a raw material crushed by a vertical crusher.SOLUTION: A method for operating a pulverizing system 200 including a vertical pulverizer 100 that pulverizes a raw material, and a circulation path 23 connected to the vertical pulverizer and configured to circulate and supply gas discharged from the vertical pulverizer to the vertical pulverizer, the method including a step of measuring a temperature or a relative humidity of the gas discharged from the vertical pulverizer, and a step of replacing a part or all of the gas circulating in the circulation path with outside air based on a measurement result of the step of measuring.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for operating a grinding system and to a grinding system. [Background technology]

[0002] A vertical mill equipped with a milling table and milling rollers inside a housing has been known as a type of vertical mill that finely mills materials to produce powder. To facilitate transport of the powder milled by the vertical mill, it is necessary to maintain the amount of moisture adhering to the powder and its moisture content at an appropriate level.

[0003] Patent Document 1 discloses a technique for detecting the moisture content of the material to be pulverized inside the vertical pulverizer and adjusting the heating temperature of the supply air based on the detected moisture content in order to maintain the pulverization performance of the vertical pulverizer. Patent Document 2 discloses a technique for preventing the powder discharged from the vertical mill from becoming too dry by controlling the flow rate and temperature of the hot gas supplied to the vertical mill according to the amount of moisture attached to the powder discharged from the vertical mill and the moisture content and the temperature of the exhaust gas discharged from the vertical mill. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-80285 [Patent Document 2] Japanese Patent Application Publication No. 1-111458 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventionally, it is necessary to adjust the heating temperature of the supply air and control the flow rate and temperature of the hot gas, which makes adjustment and control difficult.

[0006] The purpose of the method for operating a grinding system and the grinding system described in this specification is to make the moisture content of the raw material ground in the vertical grinding device appropriate and to make it easier to transport. [Means for solving the problem]

[0007] The method for operating a grinding system described in this specification is a method for operating a grinding system including a vertical grinding device that grinds raw materials and a circulation path that is connected to the vertical grinding device and circulates gas discharged from the vertical grinding device and supplies the gas to the vertical grinding device, and includes the steps of measuring the temperature or relative humidity of the gas discharged from the vertical grinding device and replacing some or all of the gas circulating through the circulation path with outside air based on the measurement results of the measuring step.

[0008] The grinding system described in this specification includes a vertical grinding device that grinds raw materials, a circulation path that is connected to the vertical grinding device and circulates gas discharged from the vertical grinding device and supplies it to the vertical grinding device, a measuring device that measures the temperature or relative humidity of the gas discharged from the vertical grinding device, an exchanging device that replaces part or all of the gas circulating through the circulation path with outside air, and a control device that controls the exchanging device based on the measurement results of the measuring device. [Effects of the Invention]

[0009] The method of operating a grinding system and the grinding system described in this specification have the effect of making it possible to adjust the moisture content of the raw material ground in the vertical grinding device to an appropriate level, making it easier to transport. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram schematically showing the configuration of a crushing system according to the first embodiment. [Figure 2] FIG. 2 is a diagram schematically showing the configuration of a vertical crushing device according to the first embodiment. [Figure 3]FIG. 3(a) is a block diagram showing a control system of the grinding system, and FIG. 3(b) is a diagram showing a schematic hardware configuration of the control device of FIG. 3(a). [Figure 4] FIG. 4 is a graph showing the relationship between the bag filter outlet humidity (%) and the powder moisture content (%). [Figure 5] Figure 5(a) is a graph (literature values) showing the relationship between temperature and saturated water vapor pressure, and Figure 5(b) is a table summarizing the saturated water vapor pressure (literature values) at temperatures between 30°C and 50°C from Figure 5(a). [Figure 6] Figure 6 is a table showing the "saturated water vapor pressure," "relative humidity," and "evaporation rate / constant" for each temperature when the water vapor pressure is constant, as well as the evaporation rate ratio ("evaporation rate ratio") for each temperature when the evaporation rate for a temperature of 45°C is set to 1.0. [Figure 7] Figure 7(a) is a table showing the evaporation rate / constant when the temperature is fixed at 45°C and the relative humidity is set to 50, 60, 70, and 80% (%), and the evaporation rate ratio (evaporation rate ratio) corresponding to each relative humidity when the evaporation rate corresponding to a relative humidity of 80% is set to 1.0. Figure 7(b) is a table showing the evaporation rate ratio when the temperature is 40°C and the relative humidity is 80% and when the temperature is 37°C and the relative humidity is 70%. [Figure 8] FIG. 8 is a flowchart showing the flow of processing by the control device. [Figure 9] FIG. 9 is a graph showing the relationship between the bag filter inlet temperature (bag filter inlet temperature) and the powder moisture content. [Figure 10] FIG. 10 is a diagram schematically showing the configuration of a crushing system according to the second embodiment. [Figure 11] FIG. 11 is a diagram showing the flow of work performed by a worker. DETAILED DESCRIPTION OF THE INVENTION

[0011] First Embodiment The grinding system 200 according to the first embodiment will be described in detail below with reference to the drawings.

[0012] FIG. 1 is a diagram showing a schematic configuration of a pulverization system 200. As shown in FIG. 1, the pulverization system 200 includes a vertical pulverizer (vertical roller mill) 100, a raw material supply unit 11, and a gas circulation and powder recovery unit 22. In this embodiment, the vertical pulverizer 100 is used to pulverize scrap electrical and electronic components as raw materials. The scrap electrical and electronic components may be incinerated at least in part or in whole to remove at least some of the organic matter, such as resin, and reduce the volume. In this embodiment, the scrap electrical and electronic components are assumed to have a large amount of moisture attached thereto.

[0013] 2 is a diagram schematically illustrating the configuration of the vertical crushing device 100 according to this embodiment. As shown in FIG. 2, the vertical crushing device 100 includes a housing 10, a feed chute 104, a crushing table 20, crushing rollers 30, and a separator 40.

[0014] The feed chute 104 feeds (supplies) the electrical and electronic component waste, which is the material to be crushed, into the center of the crushing table 20, which rotates horizontally.

[0015] The crushing table 20 has a convex central portion and a concave outer edge portion. The crushing table 20 is driven by a table drive device 110 to rotate at a constant rate around a vertically extending rotation axis. This rotation causes electrical and electronic component scraps placed in the center of the crushing table 20 to move toward the outer periphery of the crushing table 20. The value of the current supplied to the table drive device 110 is measured by an ammeter (not shown). In addition, the crushing roller 30 applies a constant force toward the crushing table 20 by a hydraulic cylinder 106. Therefore, if a difficult-to-crush object (such as a bolt or nut) enters between the crushing table 20 and the crushing roller 30, a force that hinders rotation is applied, and the value of the current supplied to the table drive device 110 increases.

[0016] A plurality of (for example, three) crushing rollers 30 are provided at positions facing the upper surface of the crushing table 20. The crushing rollers 30 apply a constant force to the crushing table 20 by means of a hydraulic cylinder 106, and crush the electric / electronic component waste that has moved to the outer edge of the crushing table 20 between the crushing rollers 30 and the crushing table 20.

[0017] In this embodiment, a gap S exists between the outer peripheral surface of the rotary table 20 and the inner wall of the housing 10. An adjustment mechanism 60 for adjusting the width of the gap S is provided in at least a part of this gap S.

[0018] In the vertical crushing apparatus 100 configured as described above, gas (air) supplied from the gas circulation and powder recovery section 22 to the lower part of the housing 10 is blown out through the gap S, creating an ascending air current within the housing 10. Therefore, the electrical and electronic component waste, which has been crushed into fine powder by the crushing table 20 and crushing rollers 30, moves further toward the periphery of the crushing table 20 and is then blown upward by the ascending air current within the housing 10. The electrical and electronic component waste is then classified (airflow classification) and transported to the separator 40 located above, where it is further classified and separated into fine powder and coarse powder. The fine powder is then collected, and the coarse powder is returned to the crushing table 20.

[0019] In this embodiment, the adjustment mechanism 60 adjusts the air speed by controlling the size of the gap S, and electrical and electronic component scraps can be separated according to size and specific gravity in accordance with Stokes' law. That is, since metal components with a high specific gravity cannot be carried upward by the air current unless they are finely crushed, this effect is used to carry only crushed electrical and electronic component scraps of a predetermined size and specific gravity or less upward by the air current, and other items that are larger in size and have a higher specific gravity (uncrushed material) fall into the gap S and can be separated (air current classification).

[0020] The fine powder (electrical and electronic component scraps) that has been transported into the separator 40 and collected is sent to the gas circulation and powder collection section 22 together with the gas discharged from the housing 10 .

[0021] On the other hand, uncrushed material that has not been crushed to fine powder by the crushing table 20 and crushing rollers 30 falls from the outer edge of the crushing table 20 into the gap S, is discharged to the outside of the vertical crushing device 100, and is transported to a storage yard by the belt conveyor 16 shown in Fig. 1. The uncrushed material that has been discharged to the outside of the housing 10 and transported to the storage yard is processed in a copper converter.

[0022] Returning to FIG. 1, the raw material supply unit 11 includes a raw material hopper 12 and a belt conveyor 14 serving as an adjustment device. The raw material hopper 12 supplies electrical and electronic component scraps onto the belt conveyor 14. The belt conveyor 14 transports the electrical and electronic component scraps toward a feed chute 104 of the vertical crusher 100. The transport speed (feed speed) of the electrical and electronic component scraps by the belt conveyor 14 can be controlled by the control device 80 shown in FIG. 3(a).

[0023] The gas circulation and powder recovery section 22 has a circulation path 23, a bag filter 24 as a recovery device, a hygrometer 32 as a measuring device, a fan 28, a circulation volume adjustment butterfly valve 34, an outside air introduction butterfly valve 36, and a heat exchanger 38.

[0024] The bag filter 24 collects fine powder (powder of crushed electrical and electronic component scraps) from the gas discharged from the vertical crusher 100 and sends the gas to the circulation path 23. The fine powder collected in the bag filter 24 is sent to the conveying device 26 via a screw conveyor or the like. The conveying device 26 includes a weighing bin, a screw conveyor, a powder and granular material conveyor (eployator), a belt conveyor, or the like, and sends the powder collected in the bag filter 24 to a copper smelting furnace. The powder is processed in the copper smelting furnace.

[0025] The hygrometer 32 is provided near the outlet of the bag filter 24, measures the relative humidity of the gas discharged from the bag filter 24 (bag filter outlet humidity), and transmits the measurement result to the control device 80 of FIG. 3(a).

[0026] The circulation amount adjustment butterfly valve 34 has a circulation damper, and the opening of the valve is adjusted by controlling the circulation damper by the control device 80 of Fig. 3(a). When the valve is opened by the circulation damper, a portion of the gas flowing through the circulation path 23 is discharged to the outside of the circulation path 23. In this embodiment, for example, when the opening of the valve by the circulation damper is 70% and 0%, the amount discharged to the outside from the circulation path 23 is smaller when the opening is 70%, and larger when the opening is 0%.

[0027] The outside air introduction butterfly valve 36 has an outside air introduction damper, and the opening of the valve is adjusted by controlling the outside air introduction damper by the control device 80 shown in Fig. 3(a). When the valve is opened by the outside air introduction damper, dry outside air is introduced into the gas flowing through the circulation path 23. Note that, for example, when the valve opening of the outside air introduction damper is 10% and 100%, the amount of dry outside air introduced into the circulation path 23 is smaller at 10% and larger at 100%.

[0028] The heat exchanger 38 has the function of raising the temperature of the gas flowing through the circulation path 23 and supplied to the vertical crusher 100 to a predetermined temperature. By raising the temperature of the gas supplied to the vertical crusher 100, the raw material electrical and electronic component scraps can be dried and made suitable for crushing by the crushing roller 30. In addition, in this embodiment, by reducing the opening of the circulation damper, the warm gas from the bag filter 24 can be circulated to the heat exchanger 38. Therefore, the waste heat of the gas from the bag filter 24 can be utilized, and the energy required to raise the temperature of the gas in the heat exchanger 38 can be reduced.

[0029] Fig. 3(a) is a block diagram showing the control system of the pulverization system 200. Note that Fig. 3(a) does not show the configuration related to the control of the vertical pulverization device 100. As shown in Fig. 3(a), the pulverization system 200 has a control device 80, which acquires the measurement results of the hygrometer 32 and controls the circulation amount adjustment butterfly valve 34, the outside air introduction butterfly valve 36, and the belt conveyor 14 based on the measurement results.

[0030] 3(b) is a diagram schematically illustrating the hardware configuration of the control device 80. The control device 80 includes a CPU 90, a ROM 92, a RAM 94, a storage (such as an SSD or HDD) 96, a communication unit 97, and a portable storage medium drive 99. These components of the control device 80 are connected to a bus 98.

[0031] Here, as described above, the control device 80 of this embodiment controls the butterfly valves 34, 36 and the belt conveyor 14 based on the relative humidity of the gas measured using the hygrometer 32 provided near the outlet of the bag filter 24. The reason for this will be explained below.

[0032] FIG. 4 is a graph showing the relationship between the relative humidity (bag filter outlet humidity (%)) measured by the hygrometer 32 at the outlet of the bag filter 24 and the moisture content of the powder collected by the bag filter 24 (powder moisture content (%)). As shown in FIG. 4, there is a proportional relationship between the bag filter outlet humidity (%) and the powder moisture content (%) as shown by an approximate formula. In other words, if the bag filter outlet humidity (%) is high, the powder moisture content (%) is high, and conversely, if the bag filter outlet humidity (%) is low, the powder moisture content (%) is low.

[0033] In order to reduce the powder moisture content, it is necessary to increase the rate at which moisture evaporates from the powder (evaporation rate). That is, in this embodiment, when the humidity at the bag filter outlet is high, it is necessary to take measures to increase the evaporation rate.

[0034] Evaporation rate J(ms -1 ), the diffusion constant of water molecules in air is D g , the volume per water molecule is v1, the radius of a water droplet in the air is R, and the vapor pressure of water in the room (n room ) and saturated water vapor pressure (n sat ) and the ratio (relative humidity) is H(=n room / n sat), it is known that it can be expressed by the following equation (1) (see, for example, 'Doi, Masao. Physics of evaporation and drying: Liquid movement and structure formation due to evaporation. Journal of the Physical Society of Japan = Butsuri. 73(8)=835:2018.8, pp.551-557. https: / / ndlsearch.ndl.go.jp / books / R000000004-I029139001'). J=D g ×v1×(n sat / R) × (1-H) … (1)

[0035] In the above equation, D g , v1, and R are constants, so the evaporation rate J is J=constant×n sat ×(1-H) …(1)' It can be expressed as:

[0036] From the above equation (1)', it can be seen that in order to increase the evaporation rate J, it is necessary to either decrease the relative humidity H or increase the saturated water vapor pressure n sat It is clear that it is necessary to increase

[0037] A more detailed explanation will be given below based on Figures 5(a) to 7(b). Figure 5(a) shows a graph of the relationship between temperature and saturated water vapor pressure. Figure 5(b) shows a table summarizing the saturated water vapor pressure at temperatures between 30°C and 50°C in Figure 5(a). The values ​​in Figures 5(a) and 5(b) are literature values.

[0038] The table in Figure 6 shows the saturated water vapor pressure n at each temperature (41°C to 50°C) when the water vapor pressure is constant (76.8 hPa). sat (hPa), relative humidity H (water vapor pressure / saturated water vapor pressure), and the evaporation rate / constant (= n sat× (1-H)". Figure 6 also shows the evaporation rate ratio (evaporation rate ratio) for each temperature, assuming that the evaporation rate at an air temperature of 45°C is 1.0. Note that the "saturated water vapor pressure" corresponding to each temperature in Figure 6 is a literature value, as in Figure 5(b), while the "relative humidity" is a value calculated from the saturated water vapor pressure and water vapor pressure, the "evaporation rate / constant" is a value calculated by substituting the saturated water vapor pressure and relative humidity values ​​into equation (1)' above, and the "evaporation rate ratio" is a value calculated from the "evaporation rate / constant" value corresponding to each temperature.

[0039] Furthermore, Figure 7(a) shows the evaporation rate / constant ratio (evaporation rate ratio) for a fixed temperature of 45°C and relative humidity of 50, 60, 70, and 80%, as well as the evaporation rate ratio for each relative humidity when the evaporation rate corresponding to 80% is set to 1.0. Note that the "saturated water vapor pressure" corresponding to the temperature (45°C) in Figure 7(a) is a literature value, as in Figures 5(b) and 6. The "evaporation rate / constant" is calculated by substituting the saturated water vapor pressure and relative humidity values ​​into Equation (1)' above. The "evaporation rate ratio" is calculated from the "evaporation rate / constant" value corresponding to each relative humidity. As shown in Figure 7(a), when the temperature is fixed at 45°C, the saturated water vapor pressure remains constant. Therefore, lowering the relative humidity at a fixed temperature means lowering the indoor water vapor pressure.

[0040] Figures 6 and 7(a) demonstrate that the evaporation rate can be increased by increasing the saturated water vapor pressure by raising the air temperature or by lowering the water vapor pressure in the room to lower the relative humidity. In contrast, in this embodiment, the temperature of the gas supplied from the heat exchanger 38 to the vertical pulverizer 100 remains nearly constant regardless of the temperature of the gas supplied to the heat exchanger 38. Therefore, lowering the water vapor pressure in the vertical pulverizer 100 is an efficient way to lower the relative humidity so as to increase the evaporation rate in the vertical pulverizer 100. Figure 7(b) shows the measured values ​​of air temperature and relative humidity obtained in an actual test. The air temperature was measured using a thermometer installed near the inlet of the bag filter 24, and the relative humidity was measured using a hygrometer 32 installed near the outlet of the bag filter 24. When the valve of the outside air intake damper was opened, dry outside air was introduced into the gas flowing through the circulation path 23, lowering the air temperature from 40°C to 37°C and the relative humidity from 80% to 70%. Assume that the evaporation rate ratio is 1.0 when the temperature inside the vertical pulverizer 100 (the inlet temperature of the bag filter 24) is 40°C (saturated vapor pressure of 74 hPa) and the relative humidity is 80%. As shown in Figure 7(b), even if the temperature drops by 3°C to 37°C (saturated vapor pressure of 63 hPa), the relative humidity can be reduced by lowering the vapor pressure of the water inside the vertical pulverizer 100. Therefore, if the relative humidity is reduced to 70%, the evaporation rate ratio can be set to 1.28. Thus, even if the temperature drops due to the introduction of outside air, the evaporation rate can be sufficiently increased by lowering the relative humidity. In Figure 7(b), the "saturated vapor pressure" corresponding to each temperature is a literature value, the "evaporation rate / constant" is a value calculated by substituting the saturated vapor pressure and relative humidity values ​​into Equation (1)' above, and the "evaporation rate ratio" is a value calculated from the "evaporation rate / constant" value corresponding to each temperature. Therefore, when the humidity at the bag filter outlet is high (i.e., when the powder moisture content is high), the control device 80 of this embodiment controls each part so that the vapor pressure of water in the vertical mill 100 decreases, thereby lowering the relative humidity in the vertical mill 100. Specific processing by the control device 80 will be described below.

[0041] (Regarding control by the control device 80) FIG. 8 is a flowchart showing the flow of processing by the control device 80.

[0042] When the process of FIG. 8 starts, first, in step S10, the control device 80 measures the relative humidity of the gas discharged from the bag filter 24 using the hygrometer 32 and acquires the measurement result.

[0043] Next, in step S12, the control device 80 determines whether the relative humidity measured by the hygrometer 32 is equal to or lower than a first threshold value (e.g., 50%). Note that the first threshold value may be a value other than 50% and may be appropriately selected, for example, within a range of 45 to 55% (e.g., a range in which the powder moisture content is approximately 2.5% to 3% in FIG. 4). If the determination in step S12 is affirmative, the process proceeds to step S14, where the control device 80 controls the circulation damper of the circulation amount adjustment butterfly valve 34 to set the valve opening to a first opening value (e.g., 70%) and controls the outside air introduction damper of the outside air introduction butterfly valve 36 to set the valve opening to a second opening value (e.g., 10%). Note that if the opening values ​​of the butterfly valves 34 and 36 have already reached the first and second opening values ​​when proceeding to step S14, no special control is performed in step S14, and the current state is maintained. After step S14, the process returns to step S10.

[0044] On the other hand, if the determination in step S12 is negative, the process proceeds to step S16, where the control device 80 determines whether the relative humidity measured by the hygrometer 32 is higher than a first threshold value (e.g., 50%) and lower than a second threshold value (e.g., 75%). The second threshold value may be a value other than 75%, and can be appropriately selected, for example, within the range of 70 to 80% (for example, a range in which the powder moisture value is around 4% to 5% in FIG. 4).

[0045] If the determination in step S16 is affirmative, the process proceeds to step S18, where the control device 80 controls the circulation damper of the circulation rate adjusting butterfly valve 34 to set the valve opening to a third opening (e.g., 0%) smaller than the first opening, and controls the outside air introduction damper of the outside air introduction butterfly valve 36 to set the valve opening to a fourth opening (e.g., 100%) larger than the second opening. Note that by performing the control in step S18, more gas discharged from the vertical mill 100 is discharged to the outside from the circulation rate adjusting butterfly valve 34 than in step S14, and more dry outside air is introduced into the circulation path 23 from the outside air introduction butterfly valve 36. In other words, by performing the process of step S18, the control device 80 can reduce the relative humidity of the gas supplied to the vertical mill 100. If the opening degrees of the butterfly valves 34, 36 have already reached the third and fourth opening degrees described above when proceeding to step S18, no particular control is performed in step S18, and the current state is maintained. After step S18, the process returns to step S10.

[0046] On the other hand, if the determination in step S16 is negative, i.e., if the relative humidity is equal to or greater than the second threshold (e.g., 75%), the process proceeds to step S20. In step S20, the control device 80 controls the circulation damper of the circulation amount adjustment butterfly valve 34 to set the valve opening to a third opening (e.g., 0%), and controls the outside air introduction damper of the outside air introduction butterfly valve 36 to set the valve opening to a fourth opening (e.g., 100%). (Note that if the process proceeds to step S20 after step S18, the openings of the butterfly valves are maintained.) The control device 80 also controls the belt conveyor 14 to reduce the feeding speed to a predetermined speed. Because the raw material, electrical and electronic component scraps, contains a large amount of moisture, reducing the feeding speed can reduce the amount of moisture in the vertical crusher 100. After step S20, the process returns to step S10.

[0047] After returning to step S10, the above-mentioned process is repeated. For example, step S10 (relative humidity measurement) is repeated at predetermined time intervals, and the relative humidity and feeding rate of the gas supplied to the vertical milling device 100 are controlled according to the relative humidity, so that the powder moisture content is adjusted to an appropriate value.

[0048] As can be seen from the above explanation, in this embodiment, the circulation amount adjustment butterfly valve 34 and the outside air introduction butterfly valve 36 function as an exchange device that exchanges part or all of the gas circulating through the circulation path 23 with outside air. Note that in this embodiment, "greater than" and "less than" may be appropriately changed to "greater than" and "smaller than (less than)", and "greater than" and "smaller than (less than)" may be appropriately changed to "greater than" and "less than".

[0049] As described above in detail, according to the first embodiment, the pulverization system 200 includes the vertical pulverizer 100 for pulverizing the raw material, which is scrap electrical and electronic components; the circulation path 23 for circulating the gas discharged from the vertical pulverizer 100 and supplying it to the vertical pulverizer 100; the hygrometer 32 for measuring the relative humidity of the gas discharged from the vertical pulverizer 100; the circulation rate adjustment butterfly valve 34 and the outside air introduction butterfly valve 36 for replacing part or all of the gas circulating through the circulation path 23 with outside air; and the control device 80 for controlling the circulation rate adjustment butterfly valve 34 and the outside air introduction butterfly valve 36 based on the measurement result of the hygrometer 32. In this way, by adjusting the vapor pressure of water in the vertical mill 100 by replacing part or all of the circulating gas with outside air based on the relative humidity of the gas discharged from the vertical mill 100, and thereby adjusting the relative humidity of the gas in the vertical mill 100, it is possible to adjust the powder moisture content of the powder discharged from the vertical mill 100 to an appropriate value. By adjusting the powder moisture content to an appropriate value in this way, when the powder recovered by the bag filter 24 is transported by a screw conveyor or the like, it is possible to prevent poor delivery on the screw conveyor, blockage of the transport path, and the like.

[0050] In the first embodiment, the opening of the circulation damper is reduced to circulate the warm gas from the bag filter 24 through the heat exchanger 38, thereby reducing the energy required to raise the gas temperature in the heat exchanger 38. Meanwhile, the gas from the bag filter 24 contains moisture due to drying the electrical and electronic component scraps in the vertical mill 100. If the moisture-containing gas is circulated and supplied to the vertical mill 100, the raw material electrical and electronic component scraps cannot be sufficiently dried in the vertical mill 100, resulting in a high powder moisture content discharged from the vertical mill 100. In this embodiment, when the powder moisture content is low, the gas from the bag filter 24 is circulated through the heat exchanger 38 to utilize waste heat. When the powder moisture content is high, some or all of the circulating gas is replaced with outside air to lower the powder moisture content. This allows for both powder moisture content control and effective energy utilization.

[0051] In the first embodiment, the pulverization system 200 includes a belt conveyor 14 that adjusts the supply speed (feeding speed) of the raw material to the vertical pulverizer 100, and the control device 80 controls the belt conveyor 14 based on the measurement results of the hygrometer 32 (S20). For example, when the relative humidity of the gas discharged from the vertical pulverizer 100 is high, the powder moisture content can be adjusted to an appropriate value by slowing down the feeding speed of the raw material (containing moisture).

[0052] In the first embodiment, when the measurement result of the hygrometer 32 is less than the second threshold, the control device 80 controls the circulation amount adjusting butterfly valve 34 and the outside air introducing butterfly valve 36 (S18), and when the measurement result of the hygrometer 32 is equal to or greater than the second threshold even after such control, the control device 80 controls the belt conveyor 14 to reduce the feeding speed to a predetermined speed. This makes it possible to adjust the powder moisture content to an appropriate value without reducing the throughput of the vertical mill 100 as much as possible.

[0053] In the first embodiment, the control device 80 controls the circulation rate adjustment butterfly valve 34, the outside air introduction butterfly valve 36, and the belt conveyor 14 according to the flowchart shown in Fig. 8, but the present invention is not limited to this. For example, when the relative humidity measured by the hygrometer 32 reaches a predetermined level or higher (e.g., 75% or higher), the control device 80 may adjust the circulation rate adjustment butterfly valve 34 and the outside air introduction butterfly valve 36 to a predetermined opening (e.g., circulation damper = 0%, outside air introduction damper = 100%), and after the adjustment, if the relative humidity does not fall below the predetermined level (e.g., below 75%) even after a predetermined time has elapsed, control the belt conveyor 14 so that the ore feeding speed becomes a predetermined speed.

[0054] In the first embodiment, the relative humidity of the gas supplied to the vertical mill 100 is adjusted by controlling the circulation amount adjusting butterfly valve 34 and the outside air introducing butterfly valve 36, but the present invention is not limited to this. That is, other mechanisms or devices capable of adjusting the relative humidity of the gas supplied to the vertical mill 100 may be provided in the circulation path 23, and the mechanisms or devices may be controlled.

[0055] In the first embodiment, the circulation rate adjustment butterfly valve 34, the outside air introduction butterfly valve 36, and the belt conveyor 14 are controlled based on the bag filter outlet humidity. However, this is not limiting. The hygrometer 32 may be installed near the bag filter inlet. In this case, the circulation rate adjustment butterfly valve 34, the outside air introduction butterfly valve 36, and the belt conveyor 14 are controlled based on the relative humidity (bag filter inlet humidity) measured by the hygrometer 32. In this case, however, it is preferable to apply a coating to the surface of the hygrometer to prevent damage by powder. For example, there is a relationship between the inlet temperature of the bag filter 24 (bag filter inlet temperature) and the powder moisture content, as shown in FIG. 9. Therefore, the circulation rate adjustment butterfly valve 34, the outside air introduction butterfly valve 36, and the belt conveyor 14 may be controlled based on the bag filter inlet temperature, as in FIG. 8. If a thermometer is installed near the inlet of the bag filter 24, it is preferable to apply a coating to the surface of the thermometer to prevent damage by powder. The thermometer may be provided on the outlet side of the bag filter.

[0056] Second Embodiment Next, a second embodiment will be described in detail with reference to Fig. 10. In the first embodiment, the circulation rate adjusting butterfly valve 34, the outside air introducing butterfly valve 36, and the belt conveyor 14 of the grinding system 200 are controlled by the control device 80. However, in the second embodiment, the opening of the circulation rate adjusting butterfly valve 34 and the outside air introducing butterfly valve 36, and the speed of the belt conveyor 14 are adjusted by an operator.

[0057] FIG. 10 is a diagram schematically illustrating the configuration of a grinding system 300 according to a second embodiment. Unlike the grinding system 200 (FIG. 1) according to the first embodiment, the grinding system 300 of FIG. 10 includes a display device 72 connected to the hygrometer 32 and a controller 74 connected to the belt conveyor 14. The display device 72 is a monitor or the like that displays the measurement results from the hygrometer 32. The display device 72 may be integrated with the hygrometer 32. The controller 74 has buttons, switches, or the like that can be operated by an operator, and adjusts the speed (conveying speed) of the belt conveyor 14 in response to the operator's operation. The controller 74 is also provided with a display that displays the speed of the belt conveyor 14. Like the grinding system 200, the grinding system 300 includes a circulation rate adjustment butterfly valve 34 and an outside air introduction butterfly valve 36. However, in the second embodiment, the operator can manually adjust the opening degrees of the circulation rate adjustment butterfly valve 34 and the outside air introduction butterfly valve 36. Here, "an operator manually adjusting the opening of the circulation volume adjustment butterfly valve 34 and the outside air introduction butterfly valve 36" means that an operator adjusts the opening of the circulation volume adjustment butterfly valve 34 and the outside air introduction butterfly valve 36, and does not mean that an operator manually opens and closes the circulation volume adjustment butterfly valve 34 and the outside air introduction butterfly valve 36. For example, the circulation volume adjustment butterfly valve 34 and the outside air introduction butterfly valve 36 may be configured as automatic valves, and the operator may open and close them by pressing an opening adjustment button on the automatic valve.

[0058] In the second embodiment, the processing that was performed by the control device 80 in the first embodiment is performed by an operator. Specifically, the operator performs the work following the flow of FIG.

[0059] First, the operator refers to the display device 72 and checks the measurement result of the hygrometer 32 (relative humidity of the gas discharged from the bag filter 24) displayed on the display device 72 (step S110).

[0060] Next, the operator checks whether the relative humidity displayed on the display device 72 is equal to or lower than a first threshold value (e.g., 50%) (step S112). If the relative humidity is equal to or lower than the first threshold value, the operator manually adjusts the circulation damper of the circulation amount adjustment butterfly valve 34 to set the valve opening to a first opening degree (e.g., 70%), and manually adjusts the outside air introduction damper of the outside air introduction butterfly valve 36 to set the valve opening degree to a second opening degree (e.g., 10%) (step S114). Note that if the opening degrees of the butterfly valves 34 and 36 are already set to the first and second opening degrees at the time of adjustment in step S114, no particular adjustment is made and the current state is maintained.

[0061] On the other hand, if the relative humidity is not equal to or lower than the first threshold (e.g., 50%), the operator checks whether the relative humidity is higher than the first threshold (e.g., 50%) and lower than the second threshold (e.g., 75%) (step S116). If the relative humidity is higher than the first threshold and lower than the second threshold (step S116: Yes), the operator adjusts the circulation damper of the circulation rate adjusting butterfly valve 34 to set the valve opening to a third opening (e.g., 0%) that is smaller than the first opening, and adjusts the outside air introduction damper of the outside air introduction butterfly valve 36 to set the valve opening to a fourth opening (e.g., 100%) that is larger than the second opening (step S118). With this adjustment, compared to the state in step S114, the circulation rate adjusting butterfly valve 34 will discharge more gas discharged from the vertical mill 100 to the outside, and the outside air introduction butterfly valve 36 will introduce more dry outside air into the circulation path 23. This reduces the relative humidity of the gas supplied to the vertical crushing apparatus 100. If the opening degrees of the butterfly valves 34 and 36 are already at the third and fourth opening degrees at the stage of adjustment in step S118, no particular adjustment is made and the current state is maintained.

[0062] On the other hand, if the relative humidity displayed on the display device 72 is equal to or greater than the second threshold (e.g., 75%) (step S116: No), the operator adjusts the circulation damper of the circulation rate adjusting butterfly valve 34 to set the valve opening to a third opening (e.g., 0%) and adjusts the outside air intake damper of the outside air intake butterfly valve 36 to set the valve opening to a fourth opening (e.g., 100%). The operator also operates the buttons and switches of the controller 74 while checking the display on the controller 74 to slow the feed speed of the belt conveyor 14 to a predetermined speed (step S120). Because the raw material, electrical and electronic component scrap, contains a large amount of moisture, slowing the feed speed can reduce the amount of moisture in the vertical crusher 100.

[0063] The worker checks the display device 72 (S110) at predetermined intervals (or at predetermined timings), and repeatedly performs the above-mentioned operations (steps S114, S118, or S120) based on the relative humidity value displayed on the display device 72.

[0064] In this embodiment, "greater than" and "less than" may be appropriately changed to "greater than" and "smaller than (less than)", and "greater than" and "smaller than (less than)" may be appropriately changed to "greater than" and "less than".

[0065] As described above, according to the second embodiment, the pulverization system 300 includes the vertical pulverizer 100 for pulverizing the raw material, electrical and electronic component scraps, and the circulation path 23 for circulating the gas discharged from the vertical pulverizer 100 and supplying it to the vertical pulverizer 100. The operator replaces some or all of the gas circulating through the circulation path 23 with outside air based on the measurement results of the relative humidity of the gas discharged from the vertical pulverizer 100. In this way, by replacing some or all of the circulating gas with outside air based on the relative humidity of the gas discharged from the vertical pulverizer 100, the vapor pressure of the water in the vertical pulverizer 100 is adjusted, and by adjusting the relative humidity of the gas in the vertical pulverizer 100, the powder moisture content of the powder discharged from the vertical pulverizer 100 can be adjusted to an appropriate value. In this way, by adjusting the powder moisture content to an appropriate value, when the powder collected in the bag filter 24 is transported by a screw conveyor or the like, it is possible to prevent poor delivery in the screw conveyor, blockage of the transport path, etc. Furthermore, it can be said that the second embodiment also achieves the other effects described in the first embodiment.

[0066] The modifications described in the first embodiment can also be applied to the second embodiment as appropriate.

[0067] In the second embodiment, the case where the worker determines what work to perform based on the relative humidity value displayed on the display device 72 has been described, but the present invention is not limited to this. For example, the control device may determine what work the worker should perform based on the relative humidity using logic similar to that shown in Figures 8 and 11, and display the determination result on the display device 72. In this case, the worker simply checks the display on the display device 72 (information on the work to be performed) and performs the work as displayed.

[0068] In addition, the control device 80 may adjust some of the opening degree of the circulation amount adjustment butterfly valve 34, the opening degree of the outside air introduction butterfly valve 36, and the speed of the belt conveyor 14, and the operator may adjust the rest.

[0069] According to one embodiment of the present disclosure, when the powder moisture value is low, the gas from the bag filter 24 is circulated through the heat exchanger 38 to utilize waste heat, and when the powder moisture value is high, some or all of the circulating gas is replaced with outside air to lower the powder moisture value. Therefore, one embodiment of the present disclosure can achieve both control of the powder moisture value and effective energy use. Therefore, one embodiment of the present disclosure has the potential to contribute to Goal 12 of the United Nations-led Sustainable Development Goals (SDGs), "Ensure sustainable consumption and production patterns."

[0070] The above-described embodiment is a preferred example of the present invention, but the present invention is not limited to this and can be modified in various ways without departing from the spirit of the present invention. [Explanation of symbols]

[0071] 14 Belt conveyor (adjustment device) 23 Circulation Route 24 Bag filter (recovery device) 32 Hygrometer (measuring device) 34 Circulation volume adjustment butterfly valve (part of the switching device) 36. Butterfly valve for fresh air intake (part of the switching device) 80 Control device 100 Vertical crusher 200 Grinding System 300 Grinding System

Claims

1. A method for operating a grinding system comprising: a vertical grinding device for grinding raw materials; and a circulation path connected to the vertical grinding device for circulating gas discharged from the vertical grinding device and supplying the gas to the vertical grinding device, the method comprising: measuring the temperature or relative humidity of the gas discharged from the vertical mill; a step of replacing a part or all of the gas circulating through the circulation path with outside air based on the measurement result of the measuring step; A method for operating a grinding system comprising:

2. 2. A method for operating a grinding system as described in claim 1, characterized in that the amount of gas circulating through the circulation path replaced with outside air is increased when the measurement result is greater than the first value and less than the second value compared to when the measurement result is less than or equal to the first value.

3. 3. The method for operating a grinding system according to claim 2, further comprising the step of adjusting a feed rate of the raw material to the vertical grinding device based on the measurement results.

4. 4. The method for operating a grinding system according to claim 3, further comprising the steps of: adjusting an amount of the gas circulating through the circulation path being replaced with outside air when the measurement result is smaller than the second value; and reducing the supply rate of the raw material to a predetermined rate when the measurement result is equal to or greater than the second value even after adjusting the amount of replacement.

5. The method for operating a grinding system according to any one of claims 1 to 4, characterized in that a recovery device is provided in the circulation path to recover the raw material that has been ground by the vertical grinding device and is transported by the gas discharged from the vertical grinding device.

6. 5. The method for operating a grinding system according to claim 1, wherein a heat exchanger for adjusting the temperature of the gas supplied to the vertical grinding device is provided in the circulation path.

7. a vertical grinding device for grinding raw materials; a circulation path connected to the vertical pulverizer, for circulating the gas discharged from the vertical pulverizer and supplying the gas to the vertical pulverizer; a measuring device for measuring the temperature or relative humidity of the gas discharged from the vertical pulverizer; an exchange device that exchanges part or all of the gas circulating through the circulation path with outside air; A control device that controls the replacing device based on the measurement results of the measuring device.

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