A superfine powder classifier for multi-stage separation of calcium hydroxide and its use method

Abstract

The invention discloses an ultrafine powder classifier for multi-stage separation of calcium hydroxide and a method for using the same. The ultrafine powder classifier comprises a plurality of classifying mechanisms arranged from bottom to top, the classifying mechanism comprising a cylindrical casing (40), a turbine casing (41) provided on the top of the casing (40), a classifying impeller (42) provided in the turbine casing (41), an air outlet (43) provided on the side wall of the turbine casing (41), and an air inlet (44) provided at the bottom of the turbine casing (41); between adjacent classifying mechanisms, the air outlet (43) of the lower separation mechanism is communicated with the inner cavity of the casing (40) of the upper separation mechanism; when viewed from bottom to top, the inner diameters of the plurality of casings (40) gradually decrease; a motor (45) is provided on the turbine casing (41) located at the top, and the motor (45) drives all the classifying impellers (42) to rotate synchronously. The invention has the advantage of high screening efficiency.

Description

Technical Field

[0001] The invention belongs to the field of calcium hydroxide production equipment, and in particular relates to an ultrafine powder classifier for multi-stage separation of calcium hydroxide and a use method thereof. Background Art

[0002] After calcium hydroxide is ground into powder, in order to meet customer requirements, it still needs to be further screened out in a classifier to obtain ultrafine powder (400 mesh to 3000 mesh).

[0003] The structure of the existing classifier includes a cylindrical body shell, a lower-level material inlet is provided at the bottom of the body shell, a turbine shell is provided at the top of the body shell, a classifying impeller is provided in the turbine shell, a classifying impeller is provided in the turbine shell, an upper-level material inlet is provided at the bottom of the turbine shell and is connected to the body shell, and a material outlet is provided on the side wall of the turbine shell.

[0004] The working principle of the existing classifier is that the airflow generated by the high-speed rotation of the classifying impeller draws the calcium hydroxide powder into the machine shell. The inertial energy of the coarse powder gradually disappears during the movement, and the lift provided by the airflow alone cannot continue to rise and will fall, while the fine powder continues to move with the airflow and is discharged from the material outlet to achieve powder classification. By controlling the speed of the classifying impeller and changing the airflow size, the classification range can be controlled.

[0005] With the development of science and technology, some industries have increasingly stringent requirements for the fineness of ultrafine powders, requiring a strict control of the fineness range above 1200 mesh. However, to screen finer ultrafine powders, the speed of the classifying impeller must be controlled at a lower speed, resulting in low classifier screening efficiency. Furthermore, the finer the ultrafine powder, the smaller the particles and the greater the surface energy, and the particles tend to aggregate automatically. When multiple ultrafine powders that meet the specifications are aggregated, they form pseudo-coarse powder. This pseudo-coarse powder, like the real coarse powder, has a higher weight, but the wind-exposed area is small, making it difficult to obtain sufficient lift and causing it to fall, further leading to low classifier screening efficiency.

[0006] Therefore, when the existing classifier is used to screen the ultrafine calcium hydroxide powder with a mesh size of more than 1200, there is a defect of low screening efficiency. Summary of the Invention

[0007] The object of the present invention is to provide an ultrafine powder classifier for multi-stage separation of calcium hydroxide and a method for using the same. The present invention has the advantage of high screening efficiency.

[0008] The technical solution of the present invention is: a superfine powder classifier for multi-stage separation of calcium hydroxide, comprising a plurality of grading mechanisms arranged from bottom to top, the grading mechanism comprising a cylindrical casing, a turbine casing provided on the top of the casing, a grading impeller provided in the turbine casing, an air outlet provided on the side wall of the turbine casing, and an air inlet provided at the bottom of the turbine casing;

[0009] Between adjacent grading mechanisms, the air outlet of the lower separation mechanism is connected to the inner cavity of the casing of the upper separation mechanism;

[0010] Looking upward from bottom to top, the inner diameters of the multiple casings gradually decrease;

[0011] An electric motor is provided on the turbine housing at the top, and the electric motor drives all the grading impellers to rotate synchronously.

[0012] In the aforementioned ultrafine powder classifier for multi-stage separation of calcium hydroxide, the motor is fixed to the turbine housing through an insulating bracket, the output end of the motor is connected to the drive shaft through an insulating coupling, the drive shaft extends downward and connects all the grading impellers, and a fixed joint is provided on one of the housings.

[0013] In the aforementioned ultrafine powder classifier for multi-stage separation of calcium hydroxide, the air outlet of the lower separation mechanism is connected to the inner cavity of the casing of the upper separation mechanism through a pipeline.

[0014] In the aforementioned ultrafine powder classifier for multi-stage separation of calcium hydroxide, there are three grading mechanisms, and conical flying discs are provided in the top and middle casings. The flying discs are fixed to the drive shaft, and a gap is left between the flying discs and the casing. A collection trough with an L-shaped cross-section is provided under the flying disc. The bottom plate of the collection trough is spiral, and the side plates of the collection trough are close to the outer edge of the flying disc. The collection trough is fixed to the inner wall of the casing, and a discharge pipe is provided at the lower end of the bottom plate, and the lower end of the discharge pipe extends into the casing at the bottom.

[0015] In the aforementioned ultrafine powder classifier for multi-stage separation of calcium hydroxide, the spiral angle of the bottom plate exceeds 360°.

[0016] In the aforementioned ultrafine powder classifier for multi-stage separation of calcium hydroxide, the material of the flying disc is titanium metal.

[0017] The aforementioned method of using the ultrafine powder classifier is to change the fineness of the screened ultrafine powder by changing the rotation speed of the motor; by connecting an electrostatic generator to one of the casings, the calcium hydroxide powder is charged with static electricity when passing through each grading mechanism, thereby increasing the repulsive force between the particles and improving the screening efficiency of the ultrafine powder classifier.

[0018] In the aforementioned method of using the ultrafine powder classifier, the ultrafine powder classifier is used in conjunction with a pendulum mill, which includes a base, an air inlet is provided on the base, a grinding ring is provided on the base, a cylinder fixed to the base is provided on the outer side of the grinding ring, a feed inlet is provided on the upper part of the cylinder, the top of the cylinder is connected to the bottom casing, a main shaft is provided in the cylinder, a plum blossom frame is provided on the top of the main shaft, a plurality of rotating shafts are distributed circumferentially on the plum blossom frame, the upper end of the rotating shaft is hinged to the plum blossom frame, a grinding roller is provided at the lower end of the rotating shaft, a friction pair is formed between the grinding roller and the grinding ring, the lower end of the main shaft passes through the base and is connected to the driving mechanism, a plurality of scrapers are provided circumferentially on the main shaft, the scrapers are in contact with the top surface of the base, and the friction surface between the grinding ring and the grinding roller is a conical surface.

[0019] In the aforementioned method of using the ultrafine powder classifier, the upper part of the conical surface is provided with a plurality of circumferentially distributed tooth grooves, the upper part of the grinding roller is provided with a plurality of circumferentially distributed teeth, the teeth cooperate with the tooth grooves, and the lower part of the grinding roller fits with the lower part of the conical surface; a spiral feeding trough is provided above the plum blossom frame, the cross-section of the feeding trough is L-shaped, the horizontal wall of the feeding trough is fixed to the cylinder, the upper end of the feeding trough is located at the feed port, the vertical arm of the feeding trough gradually decreases in height from top to bottom until it is zero, and an extension plate is provided at the lower end of the feeding trough, the upper end of the extension plate smoothly transitions to the horizontal wall of the feeding trough, the outer wall of the extension plate is fixed to the cylinder, and the lower end of the extension plate gradually shrinks toward the side of the cylinder during the downward extension process until the width is zero.

[0020] In the aforementioned method of using the ultrafine powder classifier, the spiral angle of the feed chute exceeds 360°;

[0021] A screw conveyor is provided on the outside of the cylinder, and the screw conveyor includes a feeding pipe fixed to the cylinder, one end of the feeding pipe is connected to the feeding port, and the other end of the feeding pipe is closed. A feeding hopper is provided on the side wall of the feeding pipe, and a screw is provided in the feeding pipe. A first motor connected to the screw is provided on the outside of the feeding pipe; the driving mechanism includes a second motor fixed to the base, and a driving wheel is provided at the output end of the second motor. The driving wheel is connected to the driven wheel through a belt, and the driven wheel is fixed to the lower end of the main shaft.

[0022] The air inlet is provided with a fan;

[0023] A conical plate is provided on the top of the grinding ring, the upper end of the conical plate is fixed to the inner wall of the barrel, and the lower end of the conical plate is connected to the upper end of the cone surface;

[0024] The upper end of the grinding roller is provided with a blind hole, the rotating shaft is inserted into the blind hole, the rotating shaft is connected to the grinding roller through a bearing, the lower end of the grinding roller is provided with a connecting rod, and the lower end of the connecting rod is provided with multiple circumferentially distributed blades.

[0025] Compared with the prior art, the present invention has multiple grading mechanisms, each of which is equivalent to an existing classifier. When the airflow passes through the housings of the multiple grading mechanisms, the inner diameter of the housings gradually decreases, and the flow rate of the airflow gradually increases when passing through each housing, thereby achieving multi-stage separation. For example, the fineness of the powder screened out in the first stage is 400 mesh, the second stage is 800 mesh, and the third stage is 1200 mesh. Unlike the existing classifiers that reduce the speed of the grading impeller, that is, reduce the amount of airflow per unit time to screen out finer ultrafine powders, the present invention screens out finer ultrafine powders by gradually increasing the airflow speed. The amount of airflow per unit time does not decrease, and the screening efficiency is higher. During the screening process, the housing is charged by an electrostatic generator, and the powder is charged with static electricity of the same charge, which increases the repulsive force between the powder particles, prevents the fine powder from automatically aggregating to form a pseudo-coarse powder, and prevents it from falling, further improving the screening efficiency. Through structural improvements, the present invention also enables the coarse powder formed in each grading mechanism to be quickly discharged from the corresponding casing, avoiding the accumulation of powder in the casing, so that the casing always maintains a sufficient screening height, retains sufficient screening space, and also improves the screening efficiency.

[0026] In addition, the ultrafine powder classifier on the existing production line is a separate device. After calcium hydroxide is ground in the grinding equipment, it needs to be unloaded, packaged, and transferred before it can be fed into the classifier for screening and grading. The preparatory work during this period is large and the time is long. It is not a continuous production process. This has also caused the low screening efficiency of the classifier to a certain extent. The present invention is used in conjunction with a pendulum mill (also known as a Raymond mill, or simply a mill) to achieve continuous production, without the need for preparatory work, and to improve the screening efficiency of the classifier. The pendulum mill was developed by the applicant and was originally used for the grinding of calcium oxide. However, it was found in the prototype debugging stage that it is also suitable for the grinding of calcium hydroxide, and is particularly effective when used in conjunction with the classifier in the present invention. The pendulum mill in the present invention is improved on the basis of the existing mill, has the advantage of high production efficiency, and can achieve rapid feeding of the classifier, thereby further improving the screening efficiency of the classifier.

[0027] In summary, the present invention has the advantage of high screening efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a front view of the present invention.

[0029] Figure 2 It is a top view of the turbine housing of the present invention.

[0030] Figure 3 It is a front view schematic diagram of a pendulum grinding mill.

[0031] Figure 4 It is a structural diagram of the grinding ring.

[0032] Figure 5 It is a structural diagram of the grinding roller.

[0033] Figure 6 is a top view of the extension plate.

[0034] Figure 7 This is the left side view of the extension plate.

[0035] The symbols in the accompanying drawings are: 40- housing, 41- turbine housing, 42- classifying impeller, 43- air outlet, 44- air inlet, 45- motor, 46- insulating bracket, 47- insulating coupling, 48- driving shaft, 49- fixed joint, 50- pipe, 51- flying disc, 52- collecting trough, 53- bottom plate, 54- side plate, 55- discharge pipe, 56- insulating flange; 1- base, 2- air inlet, 3- grinding ring, 4- cylinder, 5- feed port, 6- classifier, 7-spindle, 8-plum blossom frame, 9-rotating shaft, 10-grinding roller, 11-scraper, 12-conical surface, 13-tooth groove, 14-tooth, 15-feed trough, 16-extension plate, 17-feed pipe, 18-feed hopper, 19-screw, 20-first motor, 21-second motor, 22-driving wheel, 23-belt, 24-passive wheel, 25-fan, 26-bearing, 27-connecting rod, 28-blade, 29-support foot, 30-scraper frame, 31-conical plate. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the accompanying drawings and examples, but they are not intended to limit the present invention.

[0037] Example 1. A superfine powder classifier for multi-stage separation of calcium hydroxide, such as Figure 1 and Figure 2 As shown, the grading mechanism includes three grading mechanisms arranged from bottom to top. The grading mechanism includes a cylindrical casing 40. A turbine casing 41 is provided on the top of the casing 40. A grading impeller 42 is provided inside the turbine casing 41. An air outlet 43 is provided on the side wall of the turbine casing 41. An air inlet 44 is provided at the bottom of the turbine casing 41.

[0038] Between adjacent grading mechanisms, the air outlet 43 of the lower separation mechanism is connected to the inner cavity of the housing 40 of the upper separation mechanism;

[0039] Looking upward from bottom to top, the inner diameters of the multiple housings 40 gradually decrease;

[0040] An electric motor 45 is mounted on the turbine housing 41 at the top, and the electric motor 45 drives all the classifying impellers 42 to rotate synchronously. Having the same electric motor 45 drive all the classifying impellers 42 reduces the number of electric motors and equipment costs. Furthermore, the only electric motor 45 is located outside the equipment, making it easy to disassemble and assemble for maintenance.

[0041] The motor 45 is secured to the turbine housing 41 via an insulating bracket 46. The output end of the motor 45 is connected to a drive shaft 48 via an insulating coupling 47. The drive shaft 48 extends downward and connects to all of the classifying impellers 42. A fixed joint 49 is provided on one of the housings 40. When the fixed joint 49 is connected to the static electricity generator, static electricity is prevented from migrating to the motor 45, reducing the risk of equipment failure.

[0042] The air outlet 43 of the lower separation mechanism is connected to the inner cavity of the casing 40 of the upper separation mechanism through a pipe 50. There should be no hard bends on the pipe 50 to reduce the air flow resistance and reduce the power consumption of the equipment.

[0043] A conical flying disc 51 is provided in the casing 40 at the top and the middle. The flying disc 51 is fixed to the drive shaft 48. The thickness of the flying disc 51 is adjusted according to the diameter, and it is required to resonate when rotating with the drive shaft 48. The thickness value can be obtained by a simple experiment. There is a gap between the flying disc 51 and the casing 40. A collection trough 52 with an L-shaped cross-section is provided below the flying disc 51. The bottom plate 53 of the collection trough 52 is spiral. The side plate 54 of the collection trough 52 is close to the outer edge of the flying disc 51. The collection trough 52 is fixed to the inner wall of the casing 40. The lower end of the bottom plate 53 is provided with a discharge pipe 55, and the lower end of the discharge pipe 55 extends into the casing 40 at the bottom.

[0044] The helical angle of the bottom plate 53 exceeds 360°.

[0045] The flying disc 51 is made of titanium. Titanium, compared to materials like steel and copper, has a longer vibration attenuation time, which improves the resonance effect of the flying disc 51. Titanium is also the material used to make tuning forks, vibration elements of medical ultrasonic pulverizers, and diaphragms in high-end audio speakers.

[0046] The casing 40 , turbine casing 41 , classifying impeller 42 , drive shaft 48 , fixed joint 49 and pipeline 50 are all made of conductive materials, such as stainless steel.

[0047] The method of using the above-mentioned ultrafine powder classifier is to change the fineness of the screened ultrafine powder by changing the rotation speed of the motor 45; by connecting the emission rod of the electrostatic generator to the fixed joint 49, the calcium hydroxide powder is charged with static electricity of the same charge when passing through each grading mechanism, forming a repulsive force between each other, increasing the repulsive force between particles, preventing the particles from automatically aggregating to form pseudo coarse powder, and increasing the screening efficiency of the ultrafine powder classifier.

[0048] The working principle of the ultrafine powder classifier: The motor 45 rotates the drive shaft 48 through the insulating coupling 47. The drive shaft 48 drives the three classifying impellers 42 to rotate synchronously, generating an airflow. The airflow enters from the lower end of the bottom casing 40 and is discharged from the air outlet 43 of the top turbine casing 41. The calcium hydroxide powder flows with the airflow. Each time the powder passes through a casing 40, it gains a lift. The coarse powder with insufficient lift falls, while the fine powder with sufficient lift continues to rise, completing a screening process. As the diameters of the three casings 40 decrease from bottom to top, the air flow rate increases as it passes through the three casings 40. The fineness of the screened fine powder decreases until it is discharged from the air outlet 43 of the last turbine casing 41, where the discharged fine powder is an ultrafine powder that meets the fineness requirements. Among them, the powder with insufficient lifting force screened out by the bottom casing 40 falls out directly from the lower end of the bottom casing 40, and the powder with insufficient lifting force screened out by the other two casings 40 first falls onto the flying disc 51, passes through the gap between the flying disc 51 and the casing 40, falls into the collecting trough 52, spirally descends, enters the bottom casing 40 from the discharge pipe 55, and falls out.

[0049] As disc 51 rotates with drive shaft 48 and is acted upon by the external airflow, resonance occurs. The more externally assisted the vibration, the greater the amplitude. Powder falling onto disc 51 experiences this vibration, allowing some fine powder trapped within the coarse powder to escape and continue rising with the airflow, improving screening efficiency. Furthermore, the conical structure of disc 51 accelerates the outward movement of coarse powder into trough 52, preventing accumulation and maintaining the powder screening height within housing 40, thereby ensuring a consistent screening efficiency.

[0050] The above-mentioned ultrafine powder classifier is used in conjunction with a pendulum mill, which includes a base 1, an air inlet 2 is provided on the base 1, a grinding ring 3 is provided on the base 1, a cylinder 4 fixed to the base 1 is provided on the outside of the grinding ring 3, a feed port 5 is provided on the upper part of the cylinder 4, the top of the cylinder 4 is connected to the casing 40 at the bottom, and the cylinder 4 is connected to the casing 40 through an insulating flange 56, a main shaft 7 is provided in the cylinder 4, a plum blossom frame 8 is provided on the top of the main shaft 7, a plurality of rotating shafts 9 are distributed circumferentially on the plum blossom frame 8, the upper end of the rotating shaft 9 is hinged to the plum blossom frame 8, and a grinding roller 10 is provided at the lower end of the rotating shaft 9, and a friction pair is formed between the grinding roller 10 and the grinding ring 3, the lower end of the main shaft 7 passes through the base 1 and is connected to the driving mechanism, a plurality of scrapers 11 are provided circumferentially on the main shaft 7, and the scraper 11 is in contact with the top surface of the base 1, and the friction surface between the grinding ring 3 and the grinding roller 10 is a conical surface 12.

[0051] The upper part of the conical surface 12 is provided with a plurality of circumferentially distributed tooth grooves 13, and the upper part of the grinding roller 10 is provided with a plurality of circumferentially distributed teeth 14, the teeth 14 cooperate with the tooth grooves 13, and the lower part of the grinding roller 10 fits with the lower part of the conical surface 12; a spiral feeding trough 15 is provided above the plum blossom frame 8, and the cross-section of the feeding trough 15 is L-shaped. The horizontal wall of the feeding trough 15 is fixed to the cylinder 4, and the upper end of the feeding trough 15 is located at the feed port 5. The vertical arm of the feeding trough 15 gradually decreases in height from top to bottom until it is zero, and an extension plate 16 is provided at the lower end of the feeding trough 15. The upper end of the extension plate 16 smoothly transitions to the horizontal wall of the feeding trough 15, and the outer wall of the extension plate 16 is fixed to the cylinder 4. The lower end of the extension plate 16 gradually shrinks toward the side of the cylinder 4 during the downward extension process until the width is zero.

[0052] The spiral angle of the feeding trough 15 exceeds 360°;

[0053] A screw conveyor is provided on the outside of the cylinder 4, and the screw conveyor includes a feeding pipe 17 fixed to the cylinder 4, one end of the feeding pipe 17 is connected to the feed port 5, and the other end of the feeding pipe 17 is closed. A feeding hopper 18 is provided on the side wall of the feeding pipe 17, and a screw 19 is provided in the feeding pipe 17. A first motor 20 connected to the screw 19 is provided on the outside of the feeding pipe 17; the driving mechanism includes a second motor 21 fixed to the base 1, and a driving wheel 22 is provided at the output end of the second motor 21. The driving wheel 22 is connected to the driven wheel 24 through a belt 23, and the driven wheel 24 is fixed to the lower end of the main shaft 7.

[0054] The air inlet 2 is provided with a fan 25;

[0055] A conical plate 31 is provided on the top of the grinding ring 3. The upper end of the conical plate 31 is fixed to the inner wall of the barrel, and the lower end of the conical plate 31 is connected to the upper end of the conical surface 12.

[0056] The upper end of the grinding roller 10 is provided with a blind hole, the rotating shaft 9 is inserted into the blind hole, the rotating shaft 9 is connected to the grinding roller 10 through a bearing 26, the lower end of the grinding roller 10 is provided with a connecting rod 27, and the lower end of the connecting rod 27 is provided with multiple circumferentially distributed blades 28.

[0057] Instructions for using a pendulum mill: Calcium hydroxide material enters the barrel 4 through the feed hopper 18. A first motor drives the screw 19 to rotate, which delivers the material at a uniform speed. The material enters the barrel 4 through the feed port 5 and falls into the feed chute 15. Under the action of gravity, it spirals down along the feed chute 15. As the vertical arms of the feed chute 15 gradually decrease in height from top to bottom until they reach zero, the material falls out of the upper ends of the vertical arms of the feed chute 15 at a uniform speed during its descent, forming a waterfall ring. The remaining material enters the extension plate 16. As the lower end of the extension plate 16 gradually contracts toward the barrel 4 as it extends downward until its width reaches zero, the remaining material falls out of the inner edge of the extension plate 16 at a uniform speed as it continues to descend. The fallen material passes through the conical plate 31 and enters the conical surface 12 of the grinding ring 3. This structure ensures uniform downward feeding of the material into the grinding ring 3 in the annular direction.

[0058] The second motor 21 drives the driving wheel 22 to rotate, the driving wheel 22 drives the driven wheel 24 to rotate through the belt 23, the driven wheel 24 drives the main shaft 7 to rotate, and the main shaft 7 drives the scraper 11 through the scraper frame 30 to scoop up the material that has fallen onto the base 1 and feed it to the grinding ring 3 from bottom to top.

[0059] The main shaft 7 drives the rotating shaft 9 to rotate about the main shaft 7 through the plum blossom frame 8. The grinding roller 10 rolls on the conical surface 12 and, under the action of centrifugal force and its own gravity, exerts tremendous pressure on the conical surface 12, grinding the material on the conical surface 12 into powder. The grinding roller 10 drives the blade 28 to rotate through the connecting rod 27. The speed of the blade 28 can reach dozens of times the speed of the main shaft 7. At this high speed, it can effectively cut the material, especially the large particles, so that the large particles can be ground into powder more quickly.

[0060] The fan 25 supplies air to the cylinder 4, and the powder enters the casing 40 at the bottom under the action of the airflow and enters the ultrafine powder classifier. The powder that does not meet the requirements falls again and is re-ground.

[0061] Example 2. Unlike Example 1, the ultrafine powder classifier in Example 1 is used in conjunction with an existing pendulum mill. The structure of the existing pendulum mill includes a base, an air inlet is provided on the base, a grinding ring is provided on the top surface of the base, a cylinder is provided on the outside of the grinding ring, a feed inlet is provided on the upper part of the cylinder, the top of the cylinder is connected to the discharge port of the bottom casing of the classifier, a main shaft is provided in the cylinder, a plum blossom frame is provided on the top of the main shaft, a plurality of rotating shafts are distributed circumferentially on the plum blossom frame, the upper end of the rotating shaft is hinged to the plum blossom frame, a grinding roller is provided at the lower end of the rotating shaft, a friction pair is formed between the grinding roller and the grinding ring, the lower end of the main shaft passes through the base and is connected to the drive mechanism, a plurality of scrapers are provided on the main shaft, and the scrapers are in contact with the top surface of the base.

[0062] The working principle of existing grinding mills is that material enters the cylinder through the feed port and falls onto the base. The drive mechanism drives the main shaft, which in turn drives the blades and grinding rollers. The blades toss the material upward, and the material enters between the grinding rollers and the grinding ring. The grinding rollers, under the action of centrifugal force, generate outward pressure, grinding the material into powder. The air inlet is connected to a blower, creating airflow, which enters the cylinder through the air inlet. The powder is then transported to the classifier for classification.

[0063] The main difference between Example 1 and Example 2 lies in the difference in the grinding mill. The existing grinding mill in Example 2 has the following problems: first, the material thrown up by the shovel is difficult to stay on the inner wall of the grinding ring 3 for a long time, that is, the amount of material entering between the grinding ring 3 and the grinding roller is small, and the amount of material ground at one time is small, resulting in low production efficiency of the grinding mill. Second, the material particle size is uneven, with both small particles and large particles. The contact angle between small particles and the grinding roller is small, the thrust is small, the friction is large, and they will not slip, so they can be run over by the grinding roller to form powder; however, the approach angle formed by large particles on the grinding roller is large, the thrust is large, and the friction is small. Under the push of the grinding roller, they slip instead of entering between the grinding roller and the grinding ring 3, making it difficult to be smoothly ground into powder, which also leads to low production efficiency of the grinding mill.

[0064] The grinding mill in Example 1 is improved on the basis of the existing grinding mill in Example 2, and the main improvements include the following:

[0065] (1) A conical surface 12 is provided on the grinding ring 3 to match the grinding roller 10. The distance of the material falling on the conical surface 12 is increased and the speed is reduced, which increases the residence time. The amount of material entering between the grinding ring 3 and the grinding roller 10 is increased, and the amount of material ground at one time is larger, thereby increasing the production efficiency of the grinding mill.

[0066] (2) Tooth grooves 13 are provided on the conical surface 12, and teeth 14 cooperating with the tooth grooves 13 are provided on the grinding roller 10, which increases the roughness of the friction pair, making it difficult for large particles to slip and can be smoothly ground by the grinding roller 10 to form powder, or at least to form small particles. In the process of continuing to fall, they will not slide along the lower part of the smooth conical surface 12 and be ground into powder, thereby improving the production efficiency of the grinding mill.

[0067] (3) Unlike the prior art in which materials are concentrated in one place after falling from the feed port and enter the grinding ring 3, the present invention provides a screw conveyor at the feed port to transport the feed into the cylinder 4, and provides a spiral feed trough 15 above the grinding ring 3. The vertical arm of the feed trough 15 gradually decreases in height from top to bottom until it reaches zero, so that the materials sliding along the feed trough 15 can fall evenly upward and downward in the ring to form a waterfall ring, realizing uniform downward feeding. The feeding area is large, and the materials entering the grinding ring 3 can be ground into powder more quickly, thereby improving production efficiency. Moreover, the area of ​​the waterfall ring is large, and the powder in the material that originally meets the fineness specifications can be separated smoothly by the airflow and directly enter the classifier without being ground, thereby avoiding ineffective repeated grinding, which also improves production efficiency.

[0068] (4) Since the grinding principle of the grinding mill is mainly to utilize the centrifugal force generated at high speed to form a huge pressure between the grinding roller 10 and the grinding ring 3, thereby grinding the material, the speed of the grinding roller 10 rotating around the main shaft 7 is relatively high, and the grinding roller 10 moves along the grinding ring 3. Under the action of friction, the grinding roller 10 also rotates around its own axis. The speed of the grinding roller 10 rotating around its own axis can reach dozens of times the speed of the rotation around the main shaft 7. The speed of the grinding roller 10 itself is very high. The present invention sets a blade 28 under the grinding roller 10, and utilizes the high speed of the grinding roller 10 to fully cut or break up the material, which can effectively convert large particles into small particles, further increase the grinding speed, and increase the production efficiency of the grinding mill.

Claims

1. A superfine powder classifier for multi-stage separation of calcium hydroxide, characterized by: The grading mechanism comprises a plurality of grading mechanisms arranged from bottom to top, wherein the grading mechanism comprises a cylindrical casing (40), a turbine casing (41) is provided on the top of the casing (40), a grading impeller (42) is provided in the turbine casing (41), an air outlet (43) is provided on the side wall of the turbine casing (41), and an air inlet (44) is provided at the bottom of the turbine casing (41); Between adjacent grading mechanisms, the air outlet (43) of the lower separation mechanism is communicated with the inner cavity of the casing (40) of the upper separation mechanism; When viewed from bottom to top, the inner diameters of the multiple housings (40) gradually decrease; An electric motor (45) is provided on the turbine housing (41) at the top, and the electric motor (45) drives all the grading impellers (42) to rotate synchronously; The motor (45) is fixed to the turbine housing (41) via an insulating bracket (46), and the output end of the motor (45) is connected to a drive shaft (48) via an insulating coupling (47). The drive shaft (48) extends downward and connects all the grading impellers (42). A fixed joint (49) is provided on one of the housings (40); The grading mechanism has three parts, and a conical flying disc (51) is provided in the housing (40) at the top and the middle. The flying disc (51) is fixed to the drive shaft (48). A gap is left between the flying disc (51) and the housing (40). A collecting trough (52) with an L-shaped cross section is provided below the flying disc (51). The bottom plate (53) of the collecting trough (52) is spiral-shaped. The side plate (54) of the collecting trough (52) is close to the outer edge of the flying disc (51). The collecting trough (52) is fixed to the inner wall of the housing (40). A discharge pipe (55) is provided at the lower end of the bottom plate (53). The lower end of the discharge pipe (55) extends into the housing (40) at the bottom. The material of the flying disc (51) is titanium; The fixed joint (49) is connected to an electrostatic generator, and a launch rod of the electrostatic generator is connected to the fixed joint (49).

2. The ultrafine powder classifier for multi-stage separation of calcium hydroxide according to claim 1, wherein: The air outlet (43) of the lower separation mechanism is connected to the inner cavity of the casing (40) of the upper separation mechanism via a pipe (50).

3. The ultrafine powder classifier for multi-stage separation of calcium hydroxide according to claim 1, wherein: The helical angle of the bottom plate (53) exceeds 360°.

4. The method for using the ultrafine powder classifier according to any one of claims 1 to 3, characterized in that: By changing the rotation speed of the motor (45), the fineness of the screened ultrafine powder is changed; by connecting the electrostatic generator to one of the housings (40), the calcium hydroxide powder is charged with static electricity when passing through each grading mechanism, thereby increasing the repulsive force between the particles and improving the screening efficiency of the ultrafine powder classifier.

5. The method for using the ultrafine powder classifier according to claim 4, characterized in that: The ultrafine powder classifier is used in conjunction with a pendulum mill, and the pendulum mill comprises a base (1), an air inlet (2) is provided on the base (1), a grinding ring (3) is provided on the base (1), a cylinder (4) fixed to the base (1) is provided on the outside of the grinding ring (3), a feed inlet (5) is provided on the upper part of the cylinder (4), the top of the cylinder (4) is communicated with the casing (40) at the bottom, a main shaft (7) is provided in the cylinder (4), a plum blossom frame (8) is provided on the top of the main shaft (7), and the plum blossom frame A plurality of rotating shafts (9) are distributed circumferentially on (8), the upper end of the rotating shaft (9) is hinged to the plum blossom frame (8), the lower end of the rotating shaft (9) is provided with a grinding roller (10), and a friction pair is formed between the grinding roller (10) and the grinding ring (3). The lower end of the main shaft (7) passes through the base (1) and is connected to the driving mechanism. A plurality of scrapers (11) are provided circumferentially on the main shaft (7), and the scrapers (11) are in contact with the top surface of the base (1). The friction surface between the grinding ring (3) and the grinding roller (10) is a conical surface (12).

6. The method for using the ultrafine powder classifier according to claim 5, characterized in that: The upper portion of the conical surface (12) is provided with a plurality of circumferentially distributed tooth grooves (13), the upper portion of the grinding roller (10) is provided with a plurality of circumferentially distributed teeth (14), the teeth (14) cooperate with the tooth grooves (13), and the lower portion of the grinding roller (10) is in contact with the lower portion of the conical surface (12); a spiral feed trough (15) is provided above the plum blossom frame (8), the cross section of the feed trough (15) is L-shaped, and the horizontal wall of the feed trough (15) is fixed to the cylinder (4). The upper end of the feeding trough (15) is located at the feeding port (5), and the height of the vertical arm of the feeding trough (15) gradually decreases from top to bottom until it reaches zero. The lower end of the feeding trough (15) is provided with an extension plate (16), and the upper end of the extension plate (16) smoothly transitions with the horizontal wall of the feeding trough (15). The outer side wall of the extension plate (16) is fixed to the cylinder (4), and the lower end of the extension plate (16) gradually shrinks toward the side of the cylinder (4) until the width reaches zero during the process of extending downward.

7. The method for using the ultrafine powder classifier according to claim 6, characterized in that: The spiral angle of the feeding trough (15) exceeds 360°; A screw conveyor is provided on the outside of the cylinder (4), and the screw conveyor includes a feed pipe (17) fixed to the cylinder (4), one end of the feed pipe (17) is connected to the feed port (5), the other end of the feed pipe (17) is closed, a feed hopper (18) is provided on the side wall of the feed pipe (17), a screw (19) is provided in the feed pipe (17), and a first motor (20) connected to the screw (19) is provided on the outside of the feed pipe (17); the driving mechanism includes a second motor (21) fixed to the base (1), an output end of the second motor (21) is provided with a driving wheel (22), the driving wheel (22) is connected to a driven wheel (24) via a belt (23), and the driven wheel (24) is fixed to the lower end of the main shaft (7); The air inlet (2) is provided with a fan (25); A conical plate (31) is provided on the top of the grinding ring (3), the upper end of the conical plate (31) is fixed to the inner wall of the barrel, and the lower end of the conical plate (31) is connected to the upper end of the conical surface (12); The upper end of the grinding roller (10) is provided with a blind hole, the rotating shaft (9) is inserted into the blind hole, the rotating shaft (9) is connected to the grinding roller (10) via a bearing (26), the lower end of the grinding roller (10) is provided with a connecting rod (27), and the lower end of the connecting rod (27) is provided with a plurality of circumferentially distributed blades (28).

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