Preparation method of long-life magnetic lining plate based on composite magnetic circuit optimization

Abstract

The invention discloses a preparation method of a long-life magnetic lining plate based on composite magnetic circuit optimization, which comprises the following steps of: firstly, manufacturing a magnet unit of a composite magnetic circuit optimization structure: adopting an asymmetric Halbach array and multi-stage magnetic pole coupling technology, and forming an axial-radial composite magnetizing mode by N52-stage neodymium iron boron, ferrite and samarium cobalt; the main magnet is formed by stacking N52-grade neodymium iron boron and ferrite; samarium cobalt is arranged on the edge of the lining plate to form an auxiliary magnetic pole to compensate the magnetic field edge effect; embedding the magnet unit into the alloy shell, and injecting the composite adhesive for curing to form a sealing structure; in the initial assembling stage, multiple stages of broken steel balls are pre-filled, and an initial protection layer is formed through magnetic field adsorption; and in the ore grinding process, the protective layer has a self-repairing mechanism. The indexes such as the thickness stability, the magnetic field attenuation rate, the shell compressive strength and the service life of the protective layer are greatly improved, and the method is suitable for efficient ore grinding operation of magnetic minerals and non-magnetic minerals.

Description

Technical Field

[0001] The present invention relates to a technology of mine beneficiation equipment, and particularly to a preparation method of a long-life magnetic liner based on composite magnetic circuit optimization. Background Art

[0002] At present, the magnetic liners of ball mills have the following problems:

[0003] 1. Defects of traditional liners:

[0004] During the grinding process, manganese steel liners directly contact the grinding medium and ore, resulting in a high wear rate (the service life is usually 6 - 12 months). Frequent replacement leads to downtime losses.

[0005] Non-magnetic liners cannot form a protective layer, and the impact energy loss between the steel balls and the liners is large. The power consumption accounts for 30 - 40% of the total energy consumption of the concentrator.

[0006] 2. Limitations of early magnetic liners:

[0007] The single magnet structure leads to uneven magnetic field distribution, fluctuating thickness of the protective layer (10 - 25 mm), and poor adaptability to weakly magnetic ores.

[0008] In high-temperature (>80°C) or strong acid-base environments, permanent magnetic materials are prone to demagnetization, and the magnetic induction attenuation rate > 20% / year.

[0009] The compressive strength of the housing material is insufficient (<1000 MPa), and structural fractures are likely to occur in large-scale mills (Φ > 4 m).

[0010] In view of this, the present invention is specifically proposed. Summary of the Invention

[0011] The purpose of the present invention is to provide a preparation method of a long-life magnetic liner based on composite magnetic circuit optimization to solve the above technical problems existing in the prior art.

[0012] The purpose of the present invention is achieved by the following technical solutions:

[0013] The preparation method of the long-life magnetic liner based on composite magnetic circuit optimization of the present invention includes the steps:

[0014] A. Fabricating a magnet unit with a composite magnetic circuit optimization structure:

[0015] Adopting an asymmetric Halbach array and a multi-stage magnetic pole coupling technology, an axial-radial composite magnetization mode is formed by NdFeB of grade N52, ferrite, and samarium cobalt in a volume ratio of 1 to 4:4 to 8:0.5 to 1;

[0016] The main magnet is laminated by NdFeB of grade N52 and ferrite according to the above volume ratio;

[0017] Set samarium cobalt at the edge of the liner according to the above volume ratio to form an auxiliary magnetic pole and compensate for the edge effect of the magnetic field;

[0018] B. Fabricate a corrosion-resistant alloy housing:

[0019] The matrix is made of Y35BH-MoV steel with the composition: C 0.30 - 0.38%, Cr 1.00 - 2.30%, Mo 0.20 - 0.50%, V 0.10 - 0.20%, adding 1 - 2 wt% of TiC nanoparticles with a particle size of 50 - 100 nm and 0.5 - 1.0 wt% of graphene;

[0020] After ball milling and mixing under argon protection, perform hot isostatic pressing and then post-treatment;

[0021] C. Fabricate a high-temperature resistant adhesive:

[0022] Made of bisphenol A epoxy resin, nano-boehmite, and silicon carbide whiskers to form an epoxy-silicoaluminate composite adhesive (EP-SA);

[0023] D. Conduct magnet encapsulation:

[0024] Embed the magnet unit into the alloy housing, inject the composite adhesive for curing to form a sealed structure;

[0025] Successively perform magnet pre-magnetization, magnetic field curing, gradient curing, and magnetic field aging;

[0026] E. Form a gradient magnetic conduction layer structure:

[0027] Dynamic protective layer generation:

[0028] Initial installation stage: Pre-fill multi-stage crushed steel balls and use the magnetic field to adsorb to form an initial protective layer;

[0029] Operation stage: During the grinding process, make the protective layer have a self-healing mechanism.

[0030] Compared with the prior art, the preparation method of the long-life magnetic liner based on composite magnetic circuit optimization provided by the present invention realizes the following goals through technologies such as composite magnetic circuit optimization design, gradient magnetic conduction layer structure, corrosion-resistant alloy housing, and magnetic field-assisted encapsulation:

[0031] The thickness stability of the protective layer is improved to ±2 mm, adapting to magnetic / non-magnetic mixed ores;

[0032] The magnetic field attenuation rate ≤ 5% / year (working temperature ≤ 120 °C);

[0033] The compressive strength of the housing ≥ 1500 MPa, and the service life is extended to 6 - 8 times that of the traditional liner.

[0034] Applicable to the efficient grinding operation of magnetic minerals and non-magnetic minerals. Detailed implementation manners

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments, which do not constitute a limitation to the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] First, the following explanations are given for the terms that may be used in this article:

[0037] Descriptions with semantic meanings such as "including", "comprising", "containing", "having" or other similar ones should be interpreted as non-exclusive inclusion. For example, including a certain technical feature element (such as raw material, component, ingredient, carrier, dosage form, material, size, part, component, mechanism, device, step, process, method, reaction condition, processing condition, parameter, algorithm, signal, data, product or article, etc.) should be interpreted as not only including the clearly listed certain technical feature element, but also including other technical feature elements well-known in the art that are not clearly listed.

[0038] The term "consisting of..." means excluding any technical feature element that is not clearly listed. If this term is used in a claim, this term will make the claim a closed type, so that it does not include technical feature elements other than the clearly listed ones, except for the related conventional impurities. If this term only appears in a sub-clause of a claim, then it only limits the elements clearly listed in that sub-clause, and the elements recorded in other sub-clauses are not excluded from the overall claim.

[0039] The content not described in detail in the embodiments of the present invention belongs to the prior art well-known to those of ordinary skill in the art. For those conditions not specified in the embodiments of the present invention, they are carried out according to the conventional conditions in the art or the conditions recommended by the manufacturer. For the reagents or instruments not specified for the manufacturer in the embodiments of the present invention, they are all conventional products that can be obtained through commercial purchase.

[0040] The preparation method of the long-life magnetic liner based on the optimized composite magnetic circuit of the present invention includes the steps of:

[0041] A. Fabricating a magnet unit with an optimized composite magnetic circuit structure:

[0042] Adopting the asymmetric Halbach array and multi-stage magnetic pole coupling technology, and forming an axial-radial composite magnetization mode with N52 grade neodymium iron boron, ferrite and samarium cobalt in a volume ratio of 1 to 4: 4 to 8: 0.5 to 1.

[0043] The main magnet is laminated by N52 grade neodymium iron boron and ferrite according to the above volume ratio;

[0044] Samarium cobalt is arranged at the edge of the liner according to the above volume ratio to form an auxiliary magnetic pole to compensate for the edge effect of the magnetic field;

[0045] B. Fabricate a corrosion-resistant alloy housing:

[0046] The matrix uses Y35BH-MoV steel, with the composition: C 0.30 - 0.38%, Cr 1.00 - 2.30%, Mo 0.20 - 0.50%, V 0.10 - 0.20%, adding 1 - 2 wt% of TiC nanoparticles with a particle size of 50 - 100 nm and 0.5 - 1.0 wt% of graphene;

[0047] After ball milling and mixing under argon protection, hot isostatic pressing forming is carried out, and then post-treatment is carried out;

[0048] C. Fabricate a high-temperature resistant adhesive:

[0049] It is made of bisphenol A epoxy resin, nano-boehmite, and silicon carbide whiskers to form an epoxy-silicoaluminate composite adhesive (EP-SA).

[0050] D. Carry out magnet encapsulation:

[0051] Embed the magnet unit into the alloy housing, inject the composite adhesive for curing to form a sealed structure;

[0052] Successively carry out magnet pre-magnetization, magnetic field curing, gradient curing, and magnetic field aging;

[0053] E. Form a gradient magnetic conduction layer structure:

[0054] Dynamic protective layer generation:

[0055] Initial installation stage: Pre-fill multi-stage broken steel balls and use the magnetic field to adsorb to form an initial protective layer;

[0056] Operation stage: During the grinding process, make the protective layer have a self-repair mechanism.

[0057] In the said step A:

[0058] Magnetic field intensity gradient:

[0059] The surface magnetic induction intensity decreases according to a quadratic function from the center to the edge: the central area ≥ 900 mT, the edge ≥ 600 mT; [[ID=5)]

[0060] The CV value of the magnetic field uniformity ≤ 8%;

[0061] Temperature compensation:

[0062] Embed a negative temperature coefficient (NTC) ferrite sheet with a Curie point of 250 °C in the samarium cobalt magnet layer. When the temperature > 80 °C, the edge magnetic field is automatically enhanced by 5 - 8%, compensating for the high-temperature demagnetization effect.

[0063] In step B, after ball milling and mixing at 300 r / min for 8 h under argon protection, hot isostatic pressing is carried out at 1200 °C × 100 MPa × 2 h;

[0064] Post-treatment: cryogenic treatment at -196 °C for 6 h, pulsed magnetic field annealing at 5 T × 10 Hz × 30 min.

[0065] The performance indicators of the housing produced in step B include:

[0066] Compressive strength: 1820 MPa;

[0067] Fracture toughness: 135 MPa·m 1 / 2 ;

[0068] Corrosion resistance: weight loss rate < 0.01 mg / cm in H2SO4 solution with pH = 1 2 ·h.

[0069] The key properties of the high-temperature adhesive produced in step C:

[0070] Operating temperature: -50 °C to 180 °C;

[0071] Shear strength: 45 MPa (ASTM D1002);

[0072] Moisture and heat resistance: strength retention rate > 90% after 1000 h in an 85 °C / 85% RH environment.

[0073] In step D:

[0074] Magnet pre-magnetization: directional magnetization is carried out in a 3 T pulsed magnetic field.

[0075] Magnetic field curing: inject the composite adhesive in a 0.5 T uniform magnetic field, and use the magneto-orientation effect to align the SiC whiskers along the magnetic field lines;

[0076] Gradient curing: the temperature is raised stepwise from 80 °C to 150 °C, with each stage held for 1 h;

[0077] Magnetic field aging: aging treatment is carried out in a 50 Hz, 0.5 T alternating magnetic field for 24 h to eliminate internal stress and improve magnetic stability.

[0078] After step D, on-line inspection is carried out:

[0079] An industrial endoscope is used to inspect the encapsulation integrity piece by piece, achieving the effect: the porosity of the encapsulation < 1%.

[0080] In the step E:

[0081] Initial loading stage: pre-fill with multi-grade crushed steel balls, with a particle size gradient of: 2-5mm accounting for 30-50%, 5-8mm accounting for 20-40%, 8-12mm accounting for 20-40%, and use magnetic field adsorption to form an initial protective layer;

[0082] Operational phase: Enable the protection layer to have a self-repair mechanism, using one or both of the following methods:

[0083] (1) By absorbing the broken steel balls and tiny grinding media in the grinding process, the protective layer consumed in the grinding process is replenished in real time, so that it is always in a saturated state;

[0084] (2) When the mill cannot provide enough medium, the machine vision module is used to monitor the protective layer coverage in real time through a 1000fps high-speed camera. When the coverage is less than 95%, the material replenishment is triggered. For non-ferrous metal ores, small steel balls are added according to the steel ball wear rate of 0.1-0.3kg / t; an intelligent medium delivery medium library is installed at the feed end of the mill to store Φ5-8mm GCr15 steel balls.

[0085] In summary, the method for preparing a long-life magnetic liner based on composite magnetic circuit optimization in the embodiment of the present invention proposes four core innovations: "composite magnetic circuit optimization design," "gradient magnetic conductive layer structure," "corrosion-resistant alloy shell," and "magnetic field-assisted packaging technology," achieving the following goals:

[0086] The stability of the protective layer thickness is improved to ±2mm, suitable for magnetic / non-magnetic mixed ores;

[0087] Magnetic field attenuation rate ≤5% / year (operating temperature ≤120℃);

[0088] The shell compressive strength is ≥1500MPa, and its service life is extended to 6-8 times that of traditional linings.

[0089] In order to more clearly demonstrate the technical solutions and technical effects provided by the present invention, the embodiments of the present invention are described in detail below with reference to specific embodiments.

[0090] Specific technical solutions:

[0091] 1. Composite magnetic circuit optimization design

[0092] Magnet arrangement: Using asymmetric Halbach array and multi-level magnetic pole coupling technology, the main magnet unit is composed of neodymium iron boron (N52 grade), ferrite (SrFe 12 O 19 ) and samarium cobalt (Sm2Co 17 ) are composed in a certain volume ratio to form an axial-radial composite magnetization mode.

[0093] Main magnet unit: Neodymium iron boron (NdFeB N52 grade) and ferrite (SrFe 12 O 19 ) are laminated in a certain volume ratio, and the surface magnetic induction intensity ≥ 800 mT (measured value).

[0094] Auxiliary magnetic pole: Set SmCo magnet at the edge of the liner to compensate for the edge effect of the magnetic field and make the magnetic field uniformity (CV value) ≤ 8%.

[0095] Magnetic field intensity gradient: The surface magnetic induction intensity decreases according to a quadratic function from the center to the edge (center area ≥ 900 mT, edge ≥ 600 mT), solving the problem of peeling off of the edge protection layer in traditional designs.

[0096] Temperature compensation: Embed a negative temperature coefficient (NTC) ferrite sheet (Curie point 250 °C) in the SmCo magnet layer. When the temperature > 80 °C, the edge magnetic field is automatically enhanced by 5 - 8% to compensate for the high-temperature demagnetization effect.

[0097] 2. Corrosion-resistant alloy housing

[0098] (1) Nano-composite housing material

[0099] Formulation design:

[0100] The matrix uses Y35BH-MoV steel (composition: C 0.30 - 0.38%, Cr 1.00 - 2.30%, Mo 0.20 - 0.50%, V 0.10 - 0.20%), adding 1 - 2 wt% of TiC nanoparticles with a particle size of 50 - 100 nm and 0.5 - 1.0 wt% of graphene.

[0101] The preparation process includes:

[0102] Powder metallurgy: Ball milling and mixing under argon protection (300 r / min × 8 h), hot isostatic pressing (1200 °C × 100 MPa × 2 h).

[0103] Post-treatment: Deep cooling (-196 °C × 6 h) + pulsed magnetic field annealing (5 T × 10 Hz × 30 min).

[0104] Performance indicators include:

[0105] Compressive strength: 1820 MPa (15% increase)

[0106] Fracture toughness: 135 MPa·m 1 / 2 (12% increase)

[0107] Corrosion resistance: Weight loss rate < 0.01 mg / cm in H2SO4 solution with pH = 1 2 ·h (ASTM G31).

[0108] (2) High-temperature resistant adhesive

[0109] Technical solution:

[0110] Develop an epoxy-silicoaluminate composite adhesive (EP-SA), which consists of bisphenol A epoxy resin, nano-boehmite, and silicon carbide whiskers.

[0111] Key performance:

[0112] Operating temperature: -50°C to 180°C (conventional epoxy resin ≤ 120°C)

[0113] Shear strength: 45 MPa (ASTM D1002), 80% higher than conventional products

[0114] Moisture and heat resistance: Strength retention rate > 90% after 1000 h in an environment of 85°C / 85% RH

[0115] 3. Magnetic field assisted encapsulation technology

[0116] Process flow:

[0117] (1) Magnet encapsulation:

[0118] Embed the magnet unit into a prefabricated Y35BH-MoV steel alloy frame, inject EP-SA adhesive and cure it to form a sealed structure.

[0119] Magnet pre-magnetization: Orientally magnetize the NdFeB / SmCo composite magnet in a 3T pulsed magnetic field.

[0120] Magnetic field curing: Inject EP-SA adhesive in a 0.5T uniform magnetic field, and use the magneto-orientation effect to align the SiC whiskers along the magnetic field lines.

[0121] Gradient curing: Gradually increase the temperature from 80°C to 150°C in steps, and keep the temperature for 1 h at each stage.

[0122] Magnetic field aging: Age for 24 h in an alternating magnetic field (50 Hz, 0.5T) to eliminate internal stress and improve magnetic stability.

[0123] (2) In-line inspection:

[0124] Use an industrial endoscope to inspect the encapsulation integrity piece by piece.

[0125] Effect: Porosity of the encapsulation body < 1%.

[0126] 4. Gradient magnetic conductive layer structure

[0127] Dynamic protective layer generation:

[0128] Initial installation stage: Pre-fill with "multi-stage broken steel balls" (particle size gradient: 2-5mm accounts for 30-50%, 5-8mm accounts for 20-40%, 8-12mm accounts for 20-40%), and use magnetic adsorption to form an initial protective layer.

[0129] Operation stage: Enable the protective layer to have a self-repair mechanism, and there are two methods:

[0130] (1) By adsorbing broken steel balls and tiny grinding media during the grinding process, replenish the protective layer consumed during the grinding process in real time to keep it always in a saturated state.

[0131] (2) When there is not enough medium in the mill, use the machine vision module: Monitor the coverage rate of the protective layer in real time through a high-speed camera (1000fps). When the coverage rate < 95%, trigger feeding. Especially for some non-ferrous metal ores, small steel balls can be supplemented according to the steel ball wear rate of 0.1-0.3kg / t. Install an intelligent medium feeding device at the feed end of the mill, that is: Medium library: Store steel balls with a diameter of Φ5-8mm (material GCr15).

[0132] Summary of technical effects:

[0133] Through "synergistic innovation of magnetic circuit - structure - material - encapsulation", this invention achieves:

[0134] Lifetime improvement: In the application scenario of iron ore, the lining life of the secondary ball mill ≥ 10 years, and for non-ferrous metal ores ≥ 5 years;

[0135] Energy consumption reduction: The power consumption per ton of ore is reduced by 15-20%, and the steel ball consumption is reduced by 10-15%;

[0136] Enhanced universality: It can be adapted to magnetic / non-magnetic ores, dry / wet grinding, and mill specifications of Φ1.5-8m.

[0137] Example 1: Application of magnetite secondary mill (Φ3.6×6m)

[0138] Operating parameters:

[0139] Ore type: Iron ore, the specific magnetic susceptibility of the ore χ = 4.2×10 -5 m 3 / kg

[0140] Mill specification: Secondary Φ3.6×6m overflow ball mill

[0141] Steel ball size: Φ50mm (initial charge 28t)

[0142] Mill speed: 18r / min (75% of the critical speed)

[0143] Operating effect:

[0144] Protective layer thickness: 25 ± 1 mm (after 1 year of operation)

[0145] Liner wear rate: 0.05 mm per thousand hours (the traditional liner is 0.8 mm per thousand hours)

[0146] Power saving effect: The power consumption per ton of ore is reduced from 8.7 kWh to 7.2 kWh (a decrease of 17%)

[0147] Ball saving effect: The ball consumption per ton of ore is reduced from 0.85 kg / t to 0.72 kg / t (a decrease of 15%)

[0148] Example 2: Application in the first-stage mill of lead-zinc ore (Φ3.2 × 3.6 m)

[0149] Operating parameters:

[0150] Ore type: Lead-zinc ore

[0151] Mill specifications: First-stage Φ3.2 × 3.6 m grate ball mill

[0152] Steel ball specifications: Φ80 mm

[0153] Pre-filled medium: Add Φ5 mm steel balls (filling amount 1.2 t) and Φ8 mm steel balls (filling amount 0.8 t)

[0154] Magnetic field adjustment: Change the magnetic system configuration to increase the surface magnetic induction intensity from 800 mT to 950 mT

[0155] Operating effect:

[0156] The liner replacement time is shortened from 36 hours to 10 hours

[0157] Liner life: 2 years (the traditional manganese steel liner is 0.5 years)

[0158] Power saving effect: The power consumption per ton of ore is reduced from 12.9 kWh to 11.4 kWh (a decrease of 12%)

[0159] The above is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims. The information disclosed in the background art part of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of suggestion that this information constitutes the prior art known to those skilled in the art.

Claims

1. A preparation method of a long-life magnetic liner based on composite magnetic circuit optimization, characterized in that, Including the steps: A. Fabricate a magnet unit with an optimized composite magnetic circuit structure: Adopt the asymmetric Halbach array and multi-stage magnetic pole coupling technology, and form an axial-radial composite magnetization mode with N52 grade neodymium iron boron, ferrite, and samarium cobalt in a volume ratio of 1-4:4-8:0.5-1; The main magnet is laminated with N52 grade neodymium iron boron and ferrite according to the above volume ratio; Set samarium cobalt at the edge of the lining plate according to the above volume ratio to form an auxiliary magnetic pole to compensate for the magnetic field edge effect; B. Fabricate a corrosion-resistant alloy shell: The matrix uses Y35BH-MoV steel, with the composition: C 0.30-0.38%, Cr 1.00-2.30%, Mo 0.20-0.50%, V 0.10-0.20%, adding 1-2 wt% of TiC nanoparticles with a particle size of 50-100 nm and 0.5-1.0 wt% of graphene; After ball milling and mixing under argon protection, perform hot isostatic pressing forming, and then perform post-treatment; C. Fabricate a high-temperature resistant adhesive: Made of bisphenol A epoxy resin, nano-boehmite, and silicon carbide whiskers to form an epoxy-silicoaluminate composite adhesive EP-SA; D. Perform magnet encapsulation: Embed the magnet unit into the alloy shell, inject the composite adhesive for curing to form a sealed structure; Perform magnet pre-magnetization, magnetic field curing, gradient curing, and magnetic field aging in sequence; E. Form a gradient magnetic conduction layer structure: Dynamic protective layer generation: Initial installation stage: Pre-fill multi-stage broken steel balls and use the magnetic field to adsorb to form an initial protective layer; Operation stage: During the grinding process, make the protective layer have a self-repair mechanism.

2. The preparation method of the long-life magnetic liner based on composite magnetic circuit optimization according to claim 1, characterized in that In the said step A: Magnetic field intensity gradient: The surface magnetic induction intensity decreases according to a quadratic function from the center to the edge: the central area ≥ 900 mT, the edge ≥ 600 mT; The CV value of magnetic field uniformity ≤ 8%; Temperature compensation: Embed a negative temperature coefficient NTC ferrite sheet in the samarium cobalt magnet layer, with a Curie point of 250 °C. When the temperature > 80 °C, automatically enhance the edge magnetic field by 5-8% to compensate for the high-temperature demagnetization effect.

3. The preparation method of the long-life magnetic liner based on the optimization of the composite magnetic circuit according to claim 1, wherein, In the said step B, after ball milling and mixing at 300 r / min × 8 h under argon protection, perform hot isostatic pressing forming at 1200 °C × 100 MPa × 2 h; Post-treatment: Cryogenic treatment at -196 °C × 6 h, pulsed magnetic field annealing at 5 T × 10 Hz × 30 min.

4. The preparation method of the long-life magnetic liner based on the optimization of the composite magnetic circuit according to claim 3, characterized in that, The performance indicators of the shell fabricated in the said step B include: Compressive strength: 1820 MPa; Fracture toughness: 135 MPa·m 1 / 2 ; Corrosion resistance: The weight loss rate is <0.01 mg / cm 2 ·h in the H2SO4 solution with pH = 1.

5. The preparation method of the long-life magnetic liner based on the optimization of the composite magnetic circuit according to claim 1, characterized in that, The key performance of the high-temperature resistant adhesive fabricated in the said step C: Working temperature: -50 °C to 180 °C; Shear strength: 45 MPa according to ASTM D1002 standard; Moisture and heat resistance: The strength retention rate > 90% after 1000 h in an 85 °C / 85% RH environment.

6. The preparation method of the long-life magnetic liner based on composite magnetic circuit optimization according to claim 1, characterized in that In the said step D: Magnet pre-magnetization: Perform directional magnetization in a 3 T pulsed magnetic field; Magnetic field curing: Inject the composite adhesive in a 0.5 T uniform magnetic field, and use the magneto-orientation effect to make the SiC whiskers align along the magnetic force lines; Gradient curing: The temperature is increased stepwise from 80 °C to 150 °C, and each stage is kept warm for 1 h; Magnetic field aging: Aging treatment in a 50 Hz, 0.5 T alternating magnetic field for 24 h to eliminate internal stress and improve magnetic stability.

7. The preparation method of the long-life magnetic liner based on compound magnetic circuit optimization according to claim 6, characterized in that Perform on-line detection after the said step D: Industrial endoscopes are used to inspect the encapsulation integrity piece by piece, achieving the effect that the porosity of the encapsulation body is <1%.

8. The preparation method of the long-life magnetic liner based on the optimization of the composite magnetic circuit according to claim 1, characterized in that In step E described above: Initial installation stage: Pre-fill multi-stage crushed steel balls with a particle size gradient of 2 - 5 mm accounting for 30 - 50%, 5 - 8 mm accounting for 20 - 40%, and 8 - 12 mm accounting for 20 - 40%. Use magnetic adsorption to form an initial protective layer; Operation stage: Enable the protective layer to have a self-healing mechanism, and adopt any one or two of the following methods: (1) By adsorbing the crushed steel balls and tiny grinding media during the grinding process, replenish the protective layer consumed during the grinding process in real time to keep it always in a saturated state; (2) When there is not enough medium in the mill, use the machine vision module to monitor the coverage rate of the protective layer in real time through a high-speed camera with 1000 fps. When the coverage rate <95%, trigger feeding. For non-ferrous metal ores, replenish small steel balls according to the steel ball wear rate of 0.1 - 0.3 kg / t. Install an intelligent medium feeding medium library at the feed end of the mill: store steel balls made of GCr15 material with a diameter of Φ5 - 8 mm.