A mill tooth plate and a pre-treatment method and use thereof

Abstract

The present application belongs to the field of mechanical processing equipment, and particularly relates to a mill tooth plate and a pretreatment method and application thereof. The tooth plate comprises a base body, a bolt hole is arranged at the center of the base body, the bolt hole penetrates the base body from top to bottom, both sides of the top end of the base body are composed of a plurality of inverted trapezoidal structures arranged in up and down directions, wear-resistant nails are vertically embedded on the surface of the base body, cavities are arranged around the bolt hole at the bottom of the base body, magnetic blocks are arranged in the cavities, the two sides of the bottom end of the base body are interlocking structures, the interlocking structures of the bottom ends of any two base bodies can be matched, the bottom surface of the base body is matched with the curvature of the inner wall of the roller, and the base body is fixed to the roller through the countersunk bolt matched with the bolt hole. The tooth plate is used in a one-stage mill, a two-stage mill and a three-stage mill in different grinding processes, different sizes of tooth plates are used in different stages of the mill, and the thickness of the tooth plate gradually decreases in the same stage of the mill. The tooth plate and the method can improve the grinding efficiency, prolong the service life of the tooth plate, and prevent the tooth plate from loosening and falling off.

Description

Technical Field

[0001] This invention belongs to the field of machining equipment, and particularly relates to a grinding mill gear plate and a pretreatment method and its application. Background Technology

[0002] After piercing, blasting, loading, transportation, crushing, and screening, the ore enters the grinding mill. Grinding is a crucial process in ore processing, and the mill is the key equipment in this process. In existing mills, the low height of the ball-carrying plates during production results in low grinding efficiency, leading to high and uneven loads on the classifier. Simultaneously, the significant impact of the material on the plates can cause cracking, affecting normal operation. Furthermore, during high-speed operation, the vibration of the plates can easily loosen or even detach, impacting production. Summary of the Invention

[0003] The purpose of this invention is to provide a mill toothed plate and a pretreatment method and its application, which solves the problems of low ball height, easy cracking and loosening of the toothed plate.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A grinding mill tooth plate includes a base with a bolt hole at its center, extending from top to bottom through the base. The bolt hole has cuboid ends and a frustum-shaped middle section. The angle between the inclined plane of the frustum and the vertical direction ranges from 15° to 25°. The top two sides of the base are composed of multiple inverted trapezoidal structures arranged vertically, with the side structures resembling serrations. Wear-resistant nails are vertically embedded in the upper surface of the base, and these nails are integrally fused with the base. Cavities are provided at the bottom of the base around the bolt hole. The device contains a magnetic block with reinforcing ribs around its perimeter. These ribs are integrally formed with the base and are used to fix and protect the magnetic block. The bottom of the base has interlocking toothed structures on both sides, allowing any two of the base's bottom ends to mesh. Multiple bases are connected in a wave-like pattern. The bottom surface of the base matches the curvature of the inner wall of the drum. The bottom of the base is fixed to the drum by countersunk bolts. The countersunk bolts are matched with the bolt holes and fit tightly to prevent the toothed plates from loosening or falling off, while also preventing ore leakage.

[0006] Preferably, the angle between the inclined surface of the truncated pyramid in the middle section of the bolt hole and the vertical direction is 20°.

[0007] Preferably, the wear-resistant nails are arranged in a regular row with a spacing of 40-60mm.

[0008] Preferably, the wear-resistant nail is conical in shape, with the wider end being flat and fused to the substrate, embedded in the substrate; the narrower end is hemispherical and extends vertically upward, extending beyond the surface of the substrate, with a radius of 8-9 mm. The conical wear-resistant nail has self-locking properties during the grinding process and will not fall off due to wear between the substrate and the wear-resistant nail, thereby improving grinding efficiency and smooth grinding.

[0009] Preferably, the meshing structure has a protrusion and a groove on one side and a groove and a protrusion on the other side, which interlock to prevent the tooth plate from loosening and falling off.

[0010] Preferably, the magnetic block is pasted inside the cavity. The magnetic block material is neodymium iron boron magnetic powder with a particle size of 0.3-3mm. It is mixed with ethylene resin and nitrile rubber in a 3:1 ratio to form a magnetic putty, which is then filled into the cavity at the bottom of the toothed plate to form the magnetic block. The filling depth is 0.5-1.5mm lower than the height of the rib plate. The magnetic field strength of the magnetic block is 2500-3500 Gauss, so that the magnetic field strength on the surface of the toothed plate reaches 2000-3000 Gauss. During the grinding of iron ore, fine iron ore powder is generated. Since the surface of the toothed plate is magnetic, it will attract the fine iron ore powder, reducing the impact and wear of iron ore on the surface of the toothed plate and extending the service life of the toothed plate.

[0011] Preferably, the matrix material is any one of ZGMn9Cr2+ rare earth, ZGMn11Cr2Mo+ rare earth, and ZGMn5CrMo+ rare earth.

[0012] To improve the lifespan and grinding efficiency of the internal toothed plates of the grinding drum, it is necessary to increase the hardness and toughness of the internal toothed plates. That is, the toothed plates should have a strong ability to resist the indentation of external hard objects into their surface. Secondly, when external hard objects forcibly penetrate the surface of the wear-resistant material, there should be no microscopic peeling around the intrusion point due to microscopic deformation. Pretreatment of the toothed plates is crucial.

[0013] A pretreatment method for mill tooth plates, the specific steps of which are as follows:

[0014] S1: Heat preservation treatment: Heat the toothed plate inside the normal temperature drum in the furnace to 175℃~275℃, keep it at 1.5~2.5 hours, raise the temperature to 625℃~695℃ at a speed of 25℃~35℃ / hour, keep it at 4~5 hours, and then continue to raise the temperature to 1025℃~1045℃ at a speed of 45℃~55℃ / hour.

[0015] S2: Water tempering treatment: Hold at 1025℃~1045℃ for 3.5~4.5 hours, remove the toothed plate from the furnace, and place it in water for water tempering treatment for 2.5~3.5 hours. The water temperature for water tempering treatment should be controlled at 35℃~45℃. The water immersion time after removing the water tempered toothed plate from the furnace should be controlled at 3~5 minutes.

[0016] S3: Tempering treatment: Remove the toothed plate from the water and place it in a tempering furnace. Heat it to 280-330°C at a rate of 25°C-35°C / hour, hold it for 6.5-8.5 hours, and cool it at a rate of 1.5-2.0 min / mm.

[0017] S4: Aging treatment: The time is 12 to 24 months, and the time is linearly related to the material and thickness of the toothed plate.

[0018] Step S1 heat preservation allows the carbides of the high manganese steel tooth plate to completely dissolve in the austenite, thereby obtaining higher strength and toughness.

[0019] The purpose of step S2, water toughening treatment, is to eliminate carbides in the as-cast structure and obtain a single austenitic structure. Since carbides in high-manganese steel tooth plates will reduce the strength of the tooth plates and make them brittle, they are prone to casting cracks.

[0020] Step S3, tempering, causes the strength and hardness to decrease continuously, while the plasticity and toughness gradually increase.

[0021] Step S4 involves using low or room temperature, prolonged heat preservation, or heating to eliminate casting stress, which can gradually improve the plasticity and toughness of the tooth plate, eliminate internal casting stress, and extend its service life.

[0022] Various mills are designed according to different grinding processes. The first-stage mill mainly grinds coarse ore, with grinding media of Φ80~Φ120mm steel balls, a feed particle size of 0~12mm, and a product particle size of 0.15~1mm after grinding. The second-stage mill mainly grinds middlings, with grinding media of baseballs (Φ40~Φ50)×50mm, and the feed particle size is the same as that of the first-stage mill, with a particle size of 0.15~1mm, and a product particle size of 0.10~0.15mm after grinding. The third-stage mill grinds fine ore, with grinding media of baseballs (Φ15~Φ25)×30mm, and the feed particle size is the same as that of the second-stage mill, with a particle size of 0.10~0.15mm, and a product particle size of 0.1~0.075mm after fine grinding.

[0023] The toothed plates are used in first-stage, second-stage, and third-stage grinding mills for different grinding processes.

[0024] The first section of the mill toothed plate has a length of 600–1000 mm, a width of 400–600 mm, an average thickness of 60–190 mm, and an installation gap of 20 mm; the second section of the mill toothed plate has a length of 500–700 mm, a width of 300–500 mm, an average thickness of 50–130 mm, and an installation gap of 15 mm; the third section of the mill toothed plate has a length of 400–600 mm, a width of 300–500 mm, an average thickness of 40–60 mm, and an installation gap of 10 mm.

[0025] Within the same mill section, the mill drum is divided into different grinding zones based on the different grinding parts from the feed section to the discharge section. The feed grinding zone uses coarser grinding media and has a finer grinding particle than the discharge zone, resulting in greater wear on the mill tooth plates. Therefore, tooth plates of different thicknesses should be designed for different parts of the mill. Ten rows of tooth plates are installed. Taking the tooth plate at the center of the mill drum along its length as a reference, from the feed end to the discharge end, the thickness of the first row of grinding tooth plates is increased by +15 to +25 mm; the second row by +10 to +20 mm; the third row by +5 to +15 mm; the fourth row by +0 to +10 mm; and the fifth and sixth rows by +0 to +10 mm. The grinding tooth plates are thickened by -5 to +5 mm, the seventh row of grinding tooth plates is thickened by -10 to +0 mm, the eighth row of grinding tooth plates is thickened by -15 to -5 mm, the ninth row of grinding tooth plates is thickened by -20 to -10 mm, and the tenth row of grinding tooth plates is thickened by -25 to -15 mm. This creates a stepped structure with an inverted trapezoidal wave-shaped grinding tooth plate inside the mill drum, increasing the height of the balls and the impact speed. The progressively decreasing thickness of the tooth plates facilitates the outflow of slurry after grinding, improves grinding efficiency, extends the life of the internal tooth plates of the drum, and enables synchronous replacement of the front and rear tooth plates of the mill drum. This avoids the phenomenon of the internal tooth plates of the feed section drum being worn through while the internal tooth plates of the discharge section drum are thicker.

[0026] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0027] (1) The base of the toothed plate adopts an inverted trapezoidal stacking design with an inclined surface transition, which increases the height of the ball and improves the grinding efficiency;

[0028] (2) By setting magnetic blocks at the bottom of the tooth plate, the magnetic field strength on the surface of the tooth plate is enhanced. During the grinding of iron ore, the mill produces fine iron ore powder. The surface of the tooth plate will adsorb the fine iron ore powder. The fine iron ore powder can protect the tooth plate, reduce the impact and wear of iron ore on the surface of the tooth plate, prevent the tooth plate from cracking, extend the service life of the tooth plate, and reduce failures.

[0029] (3) By setting the middle section of the bolt hole to a frustum-shaped square pyramid to fit the countersunk bolt, the resistance is increased, the bolts fixing the tooth plate are prevented from loosening, and ore leakage is avoided at the same time;

[0030] (4) The toothed plate meshing structure design prevents the toothed plate from loosening and falling off;

[0031] (5) Improve the service life and grinding efficiency of the tooth plate by vertically embedding wear-resistant nails on the upper surface of the tooth plate substrate;

[0032] (6) By pre-treating the toothed plate, the hardness and toughness of the toothed plate are improved and the service life of the toothed plate is extended by heat preservation, water quenching, tempering and aging treatment respectively.

[0033] (7) In the application of toothed plates, a stepped structure with progressively decreasing thickness is adopted, which is conducive to the outflow of slurry after grinding, improves grinding efficiency, increases the service life of the toothed plates inside the drum, and avoids the phenomenon of asynchronous toothed plate replacement caused by the toothed plates in the feed section being worn through and the toothed plates in the discharge section being thicker.

[0034] (8) Optimize from multiple aspects such as structure, shape, pretreatment method and application. Multiple technical features are related, coordinated and interact with each other, reduce the mill's circulating load and return rate, solve technical problems such as low grinding efficiency inside the mill drum, loose, falling off, brittle cracks, large circulating load, many equipment failures and short tooth plate life, and improve grinding efficiency. Attached Figure Description

[0035] Figure 1 This is a front sectional view of the structure of the present invention;

[0036] Figure 2 This is a cross-sectional view of the wear-resistant nail structure of the present invention.

[0037] Explanation of reference numerals in the attached drawings: 1. Base; 2. Bolt hole; 3. Wear-resistant nail; 4. Magnetic block; 5. Rib; 6. Protrusion; 7. Groove; 8. Roller. Detailed Implementation

[0038] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0039] Our mine uses 14 mills (7 Φ3.2×4.5, 2 Φ3.2×3.5, 1 Φ5.0×6.4, 2 Φ4.3×6.1, 1 Φ3.6×4.0 and 1 Φ3.6×4.5) for coarse, medium and fine grinding of iron ore, all of which use the toothed plates of this invention. Example 1

[0040] like Figure 1-2As shown, a mill toothed plate includes a base 1 with a bolt hole 2 at its center, extending from top to bottom through the base 1. The bolt hole 2 has cuboid shapes at both ends and a frustum-shaped square in the middle. The inclined plane of the frustum-shaped square is at a 20° angle to the vertical direction. The top two sides of the base 1 are composed of multiple inverted trapezoidal structures arranged vertically, with the side structures resembling serrations. Wear-resistant nails 3 are vertically embedded in the surface of the base 1, and are integrally fused with the base 1. The wear-resistant nails 3 are arranged in regular rows. The wear-resistant nail 3 is conical in shape, with the wider end flattened and integrated into the base, while the narrower end is hemispherical and extends vertically upward beyond the base surface. The base 1 has cavities around the bolt holes at its bottom, each containing a magnetic block 4. The magnetic blocks 4 are adhered to the cavities, and reinforcing plates 5 are integrally formed with the base 1 to secure and protect the magnetic blocks. The bottom of the base 1 has interlocking toothed structures on both sides, with one side having a convex... The base has a groove 6 and a recess 7 on one side, and a recess 7 and a protrusion 6 on the other side. The protrusion 6 and the groove 7 at the bottom of any two bases can fit together. Multiple bases fit together and are connected in a wave-like pattern. The bottom surface of the base 1 fits the arc of the inner wall surface of the roller 8. The bottom of the base 1 is fixed to the roller 8 by countersunk bolts. The countersunk bolts are adapted to the bolt holes 2 and fit tightly to prevent the countersunk bolts from loosening and to prevent ore leakage. The base adopts an inverted trapezoidal stacking design to increase the height of the ball and improve grinding efficiency. Specially shaped bolt holes are used to fix the base with adapted bolts, increasing resistance and preventing the tooth plate from loosening. The wear-resistant nails are conical in shape and have self-locking properties during the grinding process, making them less likely to fall off and improving grinding efficiency. The magnetic field strength on the surface of the tooth plate is enhanced by magnetic blocks. Fine iron ore powder is adsorbed on the surface of the tooth plate. The fine iron ore powder protects the tooth plate, reduces the impact and wear of iron ore on the surface of the tooth plate, prevents the tooth plate from cracking, and extends the service life of the tooth plate. Example 2

[0041] The No. 1 mill in our mine's primary grinding mill is Φ3.6×4.5, mainly used for grinding coarse iron ore. After the crushing process, the feed particle size is 0-12mm, and the product particle size after grinding reaches 0.15-1mm. The grinding media are Φ115mm steel balls. The mill drum speed is set according to the size of the grinding media and the fineness of the ground product. The internal structure of the primary mill drum uses toothed plates, with ten rows of toothed plates, each 850mm long and 550mm wide. The thicknesses of the first to tenth rows are 125mm, 120mm, 115mm, and 110mm respectively. The grinding head sizes are 105mm, 105mm, 100mm, 95mm, 90mm, and 85mm, with a 20mm installation gap, a beveled transition, and an inverted trapezoidal structure to increase the ball height and improve grinding efficiency. Field application shows good grinding effect and low power consumption. The spacing between wear-resistant nails is 50mm. The wear-resistant nail size is Φ16*60mm, the wear-resistant nail has an inverted taper of 1:16, the narrower end ball radius is SR8, and the height exposed above the tooth plate surface is 5mm, improving the grinding effect and smooth grinding. The wear-resistant nail material is made of tungsten carbide cemented carbide tungsten steel YG15C. The bottom of the tooth plate has a 40mm deep cavity, in which a magnetic block is pasted. The magnetic block is 1mm lower than the height of the rib plate, the surface magnetic field strength reaches 3000 Gauss, and the surface adsorbed iron ore powder thickness is 60mm. The tooth plate material is ZGMn9Cr2+ rare earth. Example 3

[0042] The No. 7 mill in our mine's second-stage grinding mill is a Φ3.2×4.5 mill, primarily used for grinding medium-sized iron ore particles. The grinding media is Φ50×50mm baseballs. The mill feed is the same as the feed from the first-stage mill, with a feed particle size of 0.15–1mm. The finished product particle size is 0.10–0.15mm. The internal rollers of the second-stage mill use toothed plates with dimensions of 700mm in length and 500mm in width, installed in ten rows. The thicknesses of the first to tenth rows are 105mm, 100mm, 95mm, and 90mm respectively. The mill diameters are 85mm, 85mm, 80mm, 75mm, 70mm, and 65mm, with an installation gap of 15mm. The inclined transition increases the ball height and improves grinding efficiency. The spacing between wear-resistant nails is 50mm. The wear-resistant nail size is Φ16*60mm, the inverted taper of the wear-resistant nail is 1:16, the ball radius of the narrower end is SR8, and the height exposed above the tooth plate surface is 4mm. The wear-resistant nail material is made of tungsten carbide hard alloy tungsten steel YG15C. The bottom of the tooth plate has a 40mm deep cavity, and a magnetic block is pasted in the cavity. The magnetic block is 1.5mm lower than the height of the rib plate. The magnetic field strength on the tooth plate surface reaches 2500 Gauss, and the thickness of the iron ore powder adsorbed is 55mm. The internal tooth plate material of the No. 7 mill roller in the second stage is ZGMn11Cr2Mo+rare earth. Example 4

[0043] Our mine's No. 9 three-stage grinding mill has a model size of Φ3.2×4.5 and is mainly used for grinding fine iron ore. The grinding media is baseballs with a diameter of Φ25×30mm. The mill feed is the same as the output of the two-stage mill, with a feed particle size of 0.10~0.15mm. After fine grinding, the product particle size is 0.1~0.075mm. The internal toothed plate of the three-stage mill roller is 600mm long and 400mm wide, with ten rows of toothed plates. The thicknesses of the first to tenth rows are 75mm, 70mm, 65mm, 60mm, 55mm, 55mm, 50mm, 45mm, 40mm, and 35mm, respectively, with an installation gap of 10mm. The inclined transition increases the ball height and improves grinding efficiency. The wear-resistant nails are spaced 50mm apart and are Φ16*60mm in size. The inverted taper of the wear-resistant nails is 1:16, and the ball radius at the narrower end is SR8, with 5mm protruding from the toothed plate surface. The wear-resistant nails are made of tungsten carbide hard alloy tungsten steel YG15C. The bottom of the toothed plate has a cavity with a depth of 35mm, and magnetic blocks are pasted and filled in the cavity. The magnetic blocks are 0.5mm lower than the height of the rib plate. The magnetic field strength on the surface of the toothed plate reaches 2500 Gauss, and the thickness of the iron ore powder adsorbed is 55mm. The internal toothed plate material of the three-stage mill roller is ZGMn5CrMo+rare earth.

[0044] Examples 2-4 show that using toothed plates of different sizes in different stages of the mill naturally forms an inverted trapezoidal wave toothed plate inside the mill drum, increasing the height of the balls and the impact speed. Furthermore, the use of a stepped structure with progressively decreasing thickness within the same stage of the mill facilitates the outflow of slurry after grinding, improves grinding efficiency, extends the life of the toothed plates inside the drum, and enables synchronous replacement of the toothed plates at the front and rear of the mill. This avoids the phenomenon of the toothed plates inside the feed section drum being worn through while the toothed plates inside the discharge section drum are thicker, reducing malfunctions and improving efficiency. Example 5

[0045] A pretreatment method for mill tooth plates, the specific steps of which are as follows:

[0046] S1: Heat preservation treatment: Heat the toothed plate inside the normal temperature drum to 225℃ in the furnace and keep it at that temperature for 2 hours. Then, increase the temperature to 660℃ at a speed of 30℃ / hour and keep it at that temperature for 4.5 hours. Then, continue to increase the temperature to 1035℃ at a speed of 50℃ / hour.

[0047] S2: Water toughening treatment: After holding at 1035℃ for 4 hours, remove the toothed plate from the furnace and place it in water for water toughening treatment for 3 hours; the water temperature for water toughening treatment is controlled at 40℃; the water immersion time for the water-toughened toothed plate after removing it from the furnace is controlled at 4 minutes.

[0048] S3: Tempering treatment: Remove the toothed plate from the water and place it in a tempering furnace. Heat it to 305°C at a rate of 30°C / hour, hold it for 7.5 hours, and then cool it at a rate of 1.7 min / mm.

[0049] S4: Aging treatment: After the toothed plate is machined and cast, the treatment time is 24 months. The time is linearly related to the material and thickness of the toothed plate.

[0050] Appropriate tempering temperature and holding time can eliminate casting stress and achieve precipitation strengthening effect, improve the hardness and toughness of the tooth plate, and prevent casting cracks.

[0051] It was used successively on mills 10#, 11#, 7#, 8#, 9# and 6#, and achieved good results, extending the life of the toothed plates and improving grinding efficiency.

[0052] In summary, optimizations were made in multiple aspects, including structure, shape, pretreatment methods, and applications. These multiple technical features are interconnected and synergistic, resulting in a reduction in mill cyclic load, a 16% decrease in return ore rate, an 11% increase in grinding efficiency, a 5% decrease in failure rate, and a 15% increase in grinding output.

Claims

1. A mill tooth plate, comprising a substrate (1), characterized in that, The base (1) has a bolt hole (2) at its center, which runs through the base (1) from top to bottom. The bolt hole (2) is rectangular at both ends and a frustum of a square pyramid in the middle. The angle between the inclined plane of the frustum of the square pyramid and the vertical direction is 20°. The top two sides of the base (1) are composed of multiple inverted trapezoidal structures arranged vertically. The structures on both sides are serrated. Wear-resistant nails (3) are vertically embedded on the surface of the base (1). The wear-resistant nails (3) are integrated with the base (1). The bottom of the base (1) and the area around the bolt hole (2) are provided with cavities. Magnetic blocks (4) are provided in the cavities. Ribs (5) are provided around the magnetic blocks (4). The ribs (5) are connected to the base. The body (1) is integrally formed. The two sides of the bottom end of the base (1) are interlocking structures. Any two interlocking structures at the bottom end of the base can fit together. The bottom surface of the base (1) fits the arc of the inner wall surface of the roller (8). The bottom of the base (1) is fixed to the roller (8) by countersunk bolts. The countersunk bolts are adapted to the bolt holes (2) and the countersunk bolts are tightly fitted to the bolt holes (2). The wear-resistant nails (3) are arranged in a regular row with a spacing of 40-60mm. The wear-resistant nails (3) are conical in shape. The wider end is set as a flat head that is integrated with the base (1) and embedded in the base. The narrower end is set as a hemispherical shape that is vertically upward and extends beyond the surface of the base (1). The radius of the sphere is 8-9mm.

2. A mill toothed plate according to claim 1, characterized in that, The meshing structure has a protrusion (6) and a groove (7) on one side, and a groove (7) and a protrusion (6) on the other side.

3. A mill toothed plate according to claim 2, characterized in that, The magnetic block (4) is pasted inside the cavity. The material of the magnetic block (4) is neodymium iron boron magnetic powder with a particle size of 0.5 to 1.5 mm. It is mixed with ethylene resin and nitrile rubber as adhesives in a 3:1 ratio, and then adjusted into a magnetic mud-like state. It is filled into the cavity at the bottom of the toothed plate to form a magnetic block. The filling depth is 0.5 to 1.5 mm lower than the height of the rib plate (5).

4. A mill toothed plate according to claim 3, characterized in that, The matrix material is any one of ZGMn9Cr2+ rare earth, ZGMn11Cr2Mo+ rare earth, and ZGMn5CrMo+ rare earth.

5. The application of the toothed plate according to any one of claims 1-4, characterized in that, A single-stage, two-stage, and three-stage mill is used for different grinding processes. The toothed plates of the single-stage mill have a length of 600–1000 mm, a width of 400–600 mm, an average thickness of 60–190 mm, and an installation gap of 20 mm. The toothed plates of the two-stage mill have a length of 500–700 mm, a width of 300–500 mm, an average thickness of 50–130 mm, and an installation gap of 15 mm. The toothed plates of the three-stage mill have a length of 400–600 mm, a width of 300–500 mm, an average thickness of 40–60 mm, and an installation gap of 10 mm. After pretreatment before use, the toothed plates have a longer service life.

6. The application of the toothed plate according to claim 5, characterized in that, Ten rows of grinding teeth are installed. Taking the center position of the grinding teeth along the length of the mill drum as a reference, from the feed end to the discharge end of the mill, the thickness of the grinding teeth is increased sequentially as follows: the first row of grinding teeth is increased by +15 to +25 mm; the second row of grinding teeth is increased by +10 to +20 mm; the third row of grinding teeth is increased by +5 to +15 mm; the fourth row of grinding teeth is increased by +0 to +10 mm; the fifth and sixth rows of grinding teeth are increased by -5 to +5 mm; the seventh row of grinding teeth is increased by -10 to +0 mm; the eighth row of grinding teeth is increased by -15 to -5 mm; the ninth row of grinding teeth is increased by -20 to -10 mm; and the tenth row of grinding teeth is increased by -25 to -15 mm.

7. The application of the toothed plate according to claim 5, characterized in that, The specific steps of preprocessing are as follows: S1: Heat preservation treatment: Heat the toothed plate inside the normal temperature drum in the furnace to 175℃~275℃, keep it at 1.5~2.5 hours, raise the temperature to 625℃~695℃ at a speed of 25℃~35℃ / hour, keep it at 4~5 hours, and then continue to raise the temperature to 1025℃~1045℃ at a speed of 45℃~55℃ / hour. S2: Water tempering treatment: Hold at 1025℃~1045℃ for 3.5~4.5 hours, remove the toothed plate from the furnace, and place it in water for water tempering treatment for 2.5~3.5 hours. The water temperature for water tempering treatment should be controlled at 35℃~45℃. The water immersion time after removing the water tempered toothed plate from the furnace should be controlled at 3~5 minutes. S3: Tempering treatment: Remove the toothed plate from the water and place it in a tempering furnace. Heat it to 280-330°C at a rate of 25°C-35°C / hour, hold it for 6.5-8.5 hours, and cool it at a rate of 1.5-2.0 min / mm. S4: Aging treatment: The time is 12 to 24 months, and the time is linearly related to the material and thickness of the toothed plate.

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