Crushing apparatus and crushing method for mineral raw materials

Abstract

This method suppresses the adhesion of ore raw materials to the chute, enabling stable crushing, stabilizing the quality of the crushed raw materials, and reducing labor in cleaning and other related tasks. [Solution] The system comprises a hopper into which mineral raw materials are fed, a crusher for crushing the mineral raw materials, a chute for dropping the mineral raw materials extracted from the bottom of the hopper into the crusher, a first watering device for spraying water into the crusher, a second watering device for spraying water into the chute, and a control device for controlling the amount of water sprayed by the first and second watering devices.

Description

Technical Field

[0001] The present invention relates to a pulverizing apparatus and a pulverizing method for mineral raw materials such as cement raw materials.

Background Art

[0002] Conventionally, among the cement raw materials used in cement manufacturing facilities, mineral raw materials such as limestone are calcined after being pulverized by a pulverizing apparatus. In this pulverizing apparatus, it may contain water sprayed for dust prevention during storage and transportation or rainwater. When there is a large amount of moisture, it easily adheres to the contact surfaces of processing equipment such as belt conveyors, chutes, and hoppers, and further adheres firmly, which may cause blockages in pipes and the like.

[0003] In addition, in a vertical pulverizer, when finely pulverizing raw materials, the pulverizing roller instantaneously slides over the raw materials on the rotating table and becomes non-driven, resulting in a phenomenon where the rotation speed of the pulverizing roller does not become constant. This may lead to the occurrence of abnormal vibrations, and measures such as spraying water inside the mill are taken.

[0004] For example, Patent Document 1 discloses a method for modifying a mineral raw material that continuously measures the moisture content of the conveyed mineral raw material and adds a modifier according to the moisture content to prevent adhesion to processing equipment and clogging in the processing equipment.

[0005] Patent Document 2 discloses a control method and apparatus for a vertical mill that pulverizes cement raw materials and granular materials such as quicklime, in which the pulverized material supply amount, the amount of water sprayed inside the mill, and the pressing hydraulic pressure of the pulverizing roller are subjected to fuzzy control according to fluctuations in the pulverizing roller or mill vibration value.

[0006] Patent Document 3 discloses an operating method for a vertical grinder that effectively prevents abnormal vibrations by suppressing the occurrence of stick-slip phenomena, which involves optimizing the feeding speed of the raw material in the grinding rollers, taking into account the grinding characteristics of the raw material and the particle size after grinding. It also describes that when grinding raw materials into fine particles, a phenomenon occurs where the rotational speed of the grinding rollers becomes inconsistent as the grinding rollers momentarily slip and cease to move over the raw material on the rotating table. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2021-167442 [Patent Document 2] Japanese Patent Application Publication No. 2-122848 [Patent Document 3] Japanese Patent Publication No. 2007-7594 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, depending on the intended use, mineral raw materials such as limestone may be adversely affected by the modifier. Furthermore, while watering is a simple solution if the modifier adheres to chutes, hoppers, etc., fluctuations in the amount of moisture entering the crusher may affect the operational stability of the crushing equipment and the quality of the crushed material.

[0009] This invention has been made in view of these circumstances, and aims to suppress the adhesion of ore raw materials to the chute, thereby enabling stable pulverization, stabilizing the quality of the pulverized raw materials, and reducing labor in cleaning and other operations. [Means for solving the problem]

[0010] The mineral raw material crushing apparatus of the present invention comprises a hopper into which mineral raw materials are fed; a crushing machine for crushing the mineral raw materials; a chute for dropping the mineral raw materials extracted from the bottom of the hopper into the crushing machine; a first watering device for spraying water into the crushing machine; a second watering device for spraying water into the chute; and a control device for controlling the amount of water sprayed by the first watering device and the second watering device.

[0011] During normal operation, this crushing apparatus crushes mineral raw materials while spraying water as needed using a first water spraying device to adjust the frictional properties of the mineral raw materials. In this crushing apparatus, if mineral raw materials adhere to the inner surface of the chute, water can be sprayed onto the chute from a second water spraying device to wash away the adhered mineral raw materials with water, which then pass through the chute and fall into the crushing machine. Therefore, clogging of the chute can be prevented. Furthermore, if the amount of water supplied to the pulverizer increases due to water being sprayed into this chute, the amount of water sprayed by the first watering device can be adjusted accordingly to ensure proper pulverization.

[0012] In the mineral raw material crushing apparatus of the present invention, a static pressure measuring device is provided to measure the static pressure in the chute, and the control device controls the amount of water sprayed by the first watering device and the second watering device based on the measurement value of the static pressure measuring device.

[0013] Since the static pressure inside the chute fluctuates depending on the degree of internal blockage, blockages can be prevented by measuring the static pressure inside the chute with a static pressure meter and controlling the watering system based on that measurement.

[0014] In the mineral raw material crushing apparatus of the present invention, a moisture content measuring device is provided for measuring the moisture content of the mineral raw material extracted from the bottom of the hopper, and the control device controls the amount of water sprayed by the first watering device and the second watering device based on the measurement value of the moisture content measuring device.

[0015] When the moisture content of mineral raw materials becomes sufficiently high, they tend to adhere to the inner surface of the chute, causing it to clog. Therefore, by measuring the moisture content of the mineral raw materials before they enter the chute and controlling the watering system based on that measurement, clogging inside the chute can be prevented.

[0016] In the mineral raw material crushing apparatus of the present invention, if both the static pressure measuring instrument and the moisture content measuring instrument are provided, the control device controls the amount of water sprayed by the first watering device and the second watering device based on the static pressure measurement value from the static pressure measuring instrument and the moisture content measurement value from the moisture content measuring instrument.

[0017] By controlling the watering device while measuring both the static pressure inside the chute and the moisture content of the mineral raw material, more appropriate control can be achieved. For example, when the static pressure inside the chute exceeds a predetermined value, the measured moisture content can be used to determine whether it is due to mineral raw material with high moisture content that easily adheres to the inner surface of the chute. If the moisture content exceeds the predetermined value, it can be determined that the rise in static pressure is due to clogging inside the chute caused by mineral raw material with high moisture content, and the clogging can be cleared by spraying water with a second watering device.

[0018] On the other hand, if the measured static pressure exceeds a predetermined value, but the measured moisture content is within the normal range, it becomes possible to consider factors other than clogging in the chute and take countermeasures, thereby maintaining the grinding equipment in good working order.

[0019] The present invention relates to a method for grinding mineral raw materials, which involves grinding mineral raw materials using a grinding apparatus having a static pressure measuring device, wherein water spraying from the second watering device is started when the static pressure measurement value from the static pressure measuring device exceeds -90 mmAq, and water spraying from the second watering device is stopped when the static pressure measurement value falls below -90 mmAq.

[0020] The method for pulverizing a mineral raw material of the present invention is a method for pulverizing a mineral raw material using a pulverizing device having the moisture rate measuring device, wherein when the moisture rate measurement value by the moisture rate measuring device becomes 3% or more, watering from the second watering device is started, and when the moisture rate measurement value becomes less than 3%, watering from the second watering device is stopped.

[0021] Further, the method for pulverizing a mineral raw material of the present invention is a method for pulverizing a mineral raw material using a pulverizing device for a mineral raw material having the static pressure measuring device and the moisture rate measuring device, wherein when the static pressure measurement value by the static pressure measuring device exceeds -90 mmAq and the moisture rate measurement value by the moisture rate measuring device becomes 3% or more, watering from the second watering device is started, and when the static pressure measurement value becomes -90 mmAq or less, watering from the second watering device is stopped.

[0022] In the method for pulverizing a mineral raw material of the present invention, the mineral raw material can be limestone. It can be used for pulverizing limestone used as a cement raw material in cement production equipment.

Effects of the Invention

[0023] According to the present invention, adhesion of the ore raw material to the chute can be suppressed, stable pulverization can be performed, the quality of the pulverized raw material can be stabilized, and labor saving such as cleaning work can be achieved.

Brief Description of the Drawings

[0024] [Figure 1] It is a schematic diagram showing an embodiment of the pulverizing device of the present invention.

Embodiments for Carrying Out the Invention

[0025] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0026] FIG. 1 shows an embodiment of the pulverizing device for a mineral raw material of the present invention. This crushing apparatus 1 comprises a hopper 2 into which mineral raw materials are fed, a conveyor 3 for transporting the mineral raw materials extracted from the bottom of the hopper 2, a chute 4 connected to the end of the conveyor 3, a crusher 5 for crushing the mineral raw materials supplied from the chute, a first watering device 7 for spraying water onto a table 6 inside the crusher 5, a second watering device 8 for spraying water into the chute 4, a static pressure meter 9 for measuring the static pressure inside the chute 4, a moisture content meter 10 for measuring the moisture content of the mineral raw materials transported by the conveyor 3, and a control device 11 that controls the amount of water sprayed by the first watering device 7 and the second watering device 8 based on the measurement results of the static pressure meter 9 and the moisture content meter 10.

[0027] The hopper 2 has a cylindrical upper section and an inverted cone-shaped lower section. Mineral raw materials are fed into the hopper body 21 through the upper opening 22 and discharged through the lower opening 23 by a lower feeder (not shown). A conveyor 3 is horizontally positioned below the lower opening 23, and the mineral raw materials discharged from the hopper 2 are transported horizontally by the conveyor 3.

[0028] A moisture content measuring device 10 is installed at an intermediate position along the conveyor 3 to measure the moisture content of the mineral raw materials being transported by the conveyor 3 from above. The moisture content measuring device 10 measures the moisture content of the mineral raw materials non-contact using infrared rays, microwaves, etc., and is positioned at a predetermined height on the conveyor 3. Mineral raw materials tend to adhere to the inner surface of chute 4 if they contain a high amount of moisture (e.g., 3% or more).

[0029] The chute 4 has an upper end 24 positioned vertically, but its lower portion is formed as an inclined section 25. The upper end 24 is positioned below the end of the conveyor 3, receiving the mineral raw material falling from the end of the conveyor 3 and supplying it to the crusher 5 while sliding along the inclined section 25. The tip of this inclined section 25 is inserted into the crusher 5 and positioned above the table 6 inside the crusher 5, supplying the mineral raw material onto the table 6.

[0030] The crusher 5 crushes the mineral raw material supplied onto the table 6 by crushing it with crushing rollers (not shown) while rotating the internal table 6. The lower end of the aforementioned chute 4 is positioned directly above the center of the table 6, and the mineral raw material is supplied to the center of the table 6. Hot air flows in from the outer circumference of the table 6, and the crushed mineral raw material is blown upward to a separator 26 located above the table 6 inside the crusher 5, and sent out to the outside through the crushed raw material discharge port 27. In addition, the first watering device 7 has the tip of a watering nozzle 28 located above the table 6, and water is sprayed as needed to adjust the frictional properties of the mineral raw material.

[0031] In this type of crushing apparatus 1, the chute 4 is equipped with a static pressure measuring device 9 for measuring the internal pressure, and a second watering device 8 for spraying water into the chute 4. Thus, the watering device that sprays water onto the table 6 of the crusher 5 is designated as the first watering device 7. The static pressure measuring device 9 detects negative pressure because the pressure inside the chute 4 is affected by the negative pressure inside the crusher 5. Pressure gauges 31 and 32 are installed at the inlet and outlet of the crusher 5, respectively, and are controlled to keep the differential pressure (static pressure) constant. Normally, the static pressure measuring device 9 in the chute 4 also detects a constant value (for example, -180 mmAq).

[0032] Meanwhile, the second watering device 8 has a nozzle 33 at its tip that is positioned along the slope at the upper end of the inclined section 25 of the chute 4, and is designed to spray water from the top of the inclined section 25, causing water to flow into the inclined section 25. This water falls onto the table 6 of the crusher 5 along with the mineral raw materials. Furthermore, the first sprinkler system 7 and the second sprinkler system 8 are connected to water supply systems 34 and 35, respectively, and the flow paths are opened and closed by control valves 36 and 37.

[0033] Furthermore, the moisture content meter 10 installed on the conveyor 3 of the hopper 2, the static pressure meter 9 on the chute 4, and the inlet pressure gauge 31 and outlet pressure gauge 32 in the crusher 5 are electrically connected to the control device 11, and the control device 11 controls the first watering device 7 and the second watering device 8 based on these measured values. The control device 11 is composed of a computer equipped with a processing unit, memory, etc.

[0034] For example, a static pressure of approximately -180 mmAq in chute 4 is considered normal, and -90 mmAq is set as the threshold for starting control. Furthermore, the moisture content of the mineral raw material measured by the moisture content meter 10 is set, for example, to 3% as the threshold for starting control. Based on the measurement results from the static pressure meter 9 and the moisture content meter 10, control is performed such as spraying water into chute 4 from the second watering device 8 and limiting the watering from the first watering device 7.

[0035] Next, we will describe the case in which mineral raw material (for example, limestone) is crushed using the mineral raw material crushing apparatus 1 configured in this way. The mineral raw material stored in the hopper 2 is drawn out from the lower opening 23 by a feeder and transported on the conveyor 3. During this transport, the moisture content meter 10 sequentially measures the moisture content of the mineral raw material on the conveyor 3. Then, the mineral raw material is dropped from the end of the conveyor 3 to the upper end 24 of the chute 4 and supplied to the table 6 of the crusher 5 as it slides down the inclined section 25 of the chute 4. Inside the crusher 5, the mineral raw material is crushed by crushing rollers (not shown) while the table 6 rotates, and the crushed mineral raw material is sent out from the crushed raw material discharge port 27 at the top. At this time, the pressure readings from the inlet pressure gauge 31 and outlet pressure gauge 32 of the crusher 5 are monitored, and the differential pressure between the inlet and outlet is controlled to a predetermined value (approximately -180 mmAq). Additionally, water is sprayed onto the table 6 from the first watering device 7 as needed to crush the mineral raw material.

[0036] In this mineral raw material crushing process, the pressure inside the crusher 5 is measured by an inlet pressure gauge 31 and an outlet pressure gauge 32, and the differential pressure between them is controlled to stay within a certain range. At the same time, the mineral raw material is crushed while water is appropriately sprayed from the first watering device 7. In addition, measurement data from the inlet pressure gauge 31 and the outlet pressure gauge 32 are sent to the control device 11, and the static pressure inside the chute 4 is measured by the static pressure measuring instrument 9, and this measurement data is also sent to the control device 11. Furthermore, measurement data (moisture content measurement value) from the moisture content measuring instrument 10 on the conveyor 3 is also sent to the control device 11. Based on the data from the pressure gauges 31, 32, the static pressure measuring device 9, and the moisture content measuring device 10, the control device 11 controls the first watering device 7 of the crusher 5 and the second watering device 8 of the chute 4.

[0037] As mineral raw materials adhere to and accumulate on the inner surface of chute 4, the measurement value of the static pressure measuring instrument 9 increases. As mentioned above, the normal static pressure value is around -180 mmAq, but when mineral raw materials accumulate on the inner surface of chute 4 and the static pressure measuring instrument 9 detects a static pressure exceeding the threshold of -90 mmAq, the control device 11 checks whether the measurement data from the moisture content measuring instrument 10 indicates that the moisture content of the mineral raw materials is 3% or higher. If it is determined to be 3% or higher, the control valve 37 of the water supply system 35 of the second watering device 8 is opened and water is sprayed into chute 4.

[0038] When water is sprayed into the chute 4, the water flows down along the inclined section 25, washing away any mineral raw materials that have accumulated on the inner surface of the chute 4. The washed-away mineral raw materials slide down the chute 4 with the water and fall onto the table 6 of the crusher 5, where they are crushed. As a result, the static pressure inside the chute 4 decreases, and when it falls below -90 mmAq, the water spraying from the second watering device 8 is stopped, and normal operation resumes.

[0039] Furthermore, since the total amount of water supplied to the table 6 of the pulverizer 5 increases due to the water being sprayed from the second watering device 8, the amount of water sprayed from the first watering device 7 is limited in accordance with the amount of water sprayed from the second watering device 8. As a result, an appropriate amount of water for pulverization is always supplied to the table 6 of the pulverizer 5, enabling stable pulverization.

[0040] Furthermore, if the static pressure meter 9 detects that the static pressure inside chute 4 exceeds -90 mmAq, and the moisture content meter 10 shows a reading of less than 3%, it is possible that the cause of the static pressure increase is something other than the adhesion of mineral raw materials to the inner surface of chute 4. In such cases, inspection work will be carried out, including inspection of chute 4 and crusher 5, and confirmation of the differential pressure of crusher 5, and necessary countermeasures will be taken. If the static pressure value falls below -90 mmAq as a result of these countermeasures, operation will continue. If the inspection work suggests that the cause is a blockage in chute 4, water will be sprayed from the second watering device 8, and the water spraying from the first watering device 7 will be limited accordingly.

[0041] On the other hand, if the moisture content measurement data from the moisture content meter 10 is 3% or higher, and the static pressure measurement value from the static pressure meter 9 exceeds -90 mmAq, water will be sprayed from the second watering device 8. However, if the static pressure measurement value does not exceed -90 mmAq, operation will continue without spraying water from the second watering device 8. If the moisture content of the mineral raw material exceeds 3%, it indicates that the mineral raw material is likely to adhere to the inner surface of the chute 4. Unless the static pressure meter 9 detects that the mineral raw material has actually adhered to the inside of the chute 4, operation will continue without spraying water.

[0042] As described above, this crushing device 1 measures the moisture content of the mineral raw material using a moisture content meter 10, detects the adhesion of the mineral raw material in the chute 4 using a static pressure meter 9, and based on these detection results, can control the process by spraying water into the chute 4 from the second water spraying device 8 to remove the adhesion. Therefore, stable crushing can be maintained, improving the quality of the crushed raw material, and labor can be saved by reducing the number of times the chute 4 needs to be cleaned.

[0043] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, in the above embodiment, the water spraying from the second watering device 8 was controlled based on the measurement results of both the static pressure measuring device 9 on the chute 4 and the moisture content measuring device 10 on the conveyor 3. However, the water spraying from the second watering device 8 may be controlled based only on the measurement result of the static pressure measuring device 9 on the chute 4. In either case, the amount of water sprayed from the second watering device 8 may be set to continuously spray a constant amount until the measurement result of the static pressure measuring device 9 falls below a threshold, or a predetermined amount of water may be sprayed for a predetermined time.

[0044] Furthermore, in the above embodiment, the moisture content meter 10 was used as an auxiliary device to the static pressure meter 9, but it is also possible to spray water from the second watering device 8 based solely on the measurement results of the moisture content meter 10. For example, if the moisture content measurement value of the mineral raw material exceeds 3%, water is sprayed from the second watering device 8, and when it falls below 3%, water spraying from the second watering device 8 is stopped. Alternatively, as with the case of the static pressure meter 9 described above, it is also possible to control the system so that when the moisture content measurement value exceeds a predetermined threshold, a predetermined amount of water is sprayed from the second watering device 8 for a predetermined time.

[0045] The aforementioned threshold values ​​for measurement, such as -90 mmAq or -180 mmAq for static pressure and 3% for moisture content, can be appropriately changed depending on the type of mineral raw material to be ground, the capacity of the grinding equipment, and the type of grinding.

[0046] Furthermore, water may be periodically supplied from the second sprinkler system 8 regardless of whether chute 4 becomes clogged. In that case, the amount of water supplied from the first sprinkler system 7 should be controlled according to the amount of water supplied from the second sprinkler system 8. Alternatively, while water is being supplied periodically, the amount of water supplied from the second sprinkler system 8 can be increased if the reading on the static pressure meter 9 rises. Furthermore, while limestone, used as a cement raw material, was given as an example of a mineral raw material, the present invention can be used to crush other cement raw materials such as silica, or other general mineral raw materials. [Explanation of Symbols]

[0047] 1. Grinding device 2 Hoppers 3 Conveyor 4 shots 5. Crusher 6 tables 7. First sprinkler system 8. Second sprinkler system 9. Static pressure measuring instrument 10 Moisture content meter 11 Control device 21 Hopper body 22 Upper opening 23 Lower opening 24 Upper end 25 Slope 26 Separators 27 Discharge port for crushed raw materials 28 Sprinkler nozzles 31 Inlet pressure gauge 32 Outlet pressure gauge 33 nozzles 34,35 Water supply system 36,37 Control valves

Claims

1. A mineral raw material crushing apparatus comprising: a hopper into which mineral raw materials are fed; a crusher for crushing the mineral raw materials; a chute for dropping the mineral raw materials extracted from the bottom of the hopper into the crusher; a first watering device for spraying water into the crusher; a second watering device for spraying water into the chute; and a control device for controlling the amount of water sprayed by the first watering device and the second watering device.

2. The crushing apparatus for mineral raw materials according to claim 1, further comprising a static pressure measuring device for measuring the static pressure in the chute, wherein the control device controls the amount of water sprayed by the first watering device and the second watering device based on the measurement value of the static pressure measuring device.

3. The crushing apparatus for mineral raw materials according to claim 1, further comprising a moisture content measuring instrument for measuring the moisture content of the mineral raw material extracted from the lower part of the hopper, wherein the control device controls the amount of water sprayed by the first watering device and the second watering device based on the measurement value of the moisture content measuring instrument.

4. The device further comprises a moisture content measuring instrument for measuring the moisture content of the mineral raw material extracted from the lower part of the hopper. The mineral raw material crushing apparatus according to claim 2, characterized in that the control device controls the amount of water sprayed by the first watering device and the second watering device based on the static pressure measurement value obtained by the static pressure measuring device and the moisture content measurement value obtained by the moisture content measuring device.

5. A method for crushing mineral raw materials using the mineral raw material crushing apparatus described in claim 2, A method for crushing mineral raw materials, characterized in that water spraying from the second water spraying device is started when the static pressure measurement value obtained by the static pressure measuring device exceeds -90 mmAq, and water spraying from the second water spraying device is stopped when the static pressure measurement value falls below -90 mmAq.

6. A method for crushing mineral raw materials using the mineral raw material crushing apparatus described in claim 3, A method for crushing mineral raw materials, characterized in that water spraying from the second watering device is started when the moisture content measurement value obtained by the moisture content meter becomes 3% or more, and water spraying from the second watering device is stopped when the moisture content measurement value becomes less than 3%.

7. A method for crushing mineral raw materials using the mineral raw material crushing apparatus described in claim 4, A method for crushing mineral raw materials, characterized in that when the static pressure measurement value obtained by the static pressure measuring instrument exceeds -90 mmAq and the moisture content measurement value obtained by the moisture content measuring instrument is 3% or more, water spraying from the second watering device is started, and when the static pressure measurement value falls to -90 mmAq or less, water spraying from the second watering device is stopped.

8. The method for crushing a mineral raw material according to any one of claims 4 to 7, characterized in that the mineral raw material is limestone.

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