Strip steel continuous treatment process based on silicon carbide brush roll activation and high-speed pickling

Abstract

The invention discloses a continuous strip steel treatment process based on silicon carbide brush roller activation and high-speed pickling. The continuous strip steel treatment process comprises the following steps of strip steel surface treatment, gradient pickling solution spraying, strip steel vortex-micro-current treatment, waste liquid regeneration and metal recovery. Flexible contact and rigid removal of the strip steel surface oxide layer are achieved through brush wires of the silicon carbide brush roller, dynamic adjustment of the rotating speed and pressure of the silicon carbide brush roller is matched, the motion trail of the silicon carbide brush roller is in a sweeping-shearing composite mode, the strip steel treatment speed reaches 20 mpm, and the strip steel surface oxide layer removal efficiency is remarkably improved; and meanwhile, the service life of the silicon carbide brush roller is prolonged to 200 hours, the dissolution rate of Cr and Mo oxides in the pickling solution is increased through thiourea, HEDP and a wetting agent, Cr and Mo are conveniently recycled, bipolar membrane electrodialysis treatment is conducted on the pickling solution, HNO3 is recycled and directly reused in a pickling tank, zero waste liquid discharge is achieved, and the method is more environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of strip pickling technology, specifically a continuous strip processing technology based on silicon carbide brush roller activation and high-speed pickling. Background Technology

[0002] Super duplex stainless steel 2507 is a highly alloyed duplex stainless steel that combines the advantages of austenitic and ferritic stainless steels. It possesses extremely high resistance to pitting corrosion, crevice corrosion, and stress corrosion cracking, making it particularly suitable for chlorine-containing and acidic environments. Therefore, the processing technology for super duplex stainless steel 2507 is relatively complex, requiring specialized techniques and control.

[0003] Currently, continuous pickling of super duplex stainless steel 2507 strip (thickness 2.5~6.0mm) faces the following technical bottlenecks: Low efficiency: Traditional sandblasting / belt grinding pretreatment and traditional pickling are limited in speed (≤5mpm) due to the difficulty in removing oxide scale. If production is accelerated, it often leads to insufficient pickling; Surface damage: Abrasive belt grinding easily causes scratches on the substrate (depth >1μm), requiring an additional polishing process; High environmental costs: Due to the relatively dense oxide scale of super duplex stainless steel 2507 strip, high-concentration pickling solution is required, resulting in a high proportion of waste liquid treatment costs in the total cost.

[0004] In existing technologies, ceramic brush rollers are used for pretreatment, but problems such as rapid brush filament wear (lifetime < 100 hours) and uneven oxide layer removal (fluctuation ±15%) exist, which cannot meet the needs of high-speed continuous production. Summary of the Invention

[0005] The purpose of this invention is to provide a continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling, characterized by comprising the following steps:

[0007] Step 1: Strip surface treatment. The strip is re-grinded and pre-activated by silicon carbide brush rollers at a speed of 20 mpm. The brush filament length is monitored in real time by a laser rangefinder. When the brush filament wear is greater than 10%, the distance between the silicon carbide brush rollers and the strip is adjusted.

[0008] Step two involves gradient pickling solution spraying. The pickling solution comprises HF, HNO, HEDP, thiourea, polyether-modified siloxane wetting agent, and HO. The pickling solution is sprayed through a fan-shaped nozzle array at a pressure of 2-2.5 MPa, covering the entire strip width. The contact time between the pickling solution and the strip is ≤3 seconds.

[0009] Step 3: Eddy current-microcurrent treatment of the strip steel. The pickling interface temperature of the strip steel is maintained by a high-frequency induction coil. A square wave pulse current is applied to the strip steel by the titanium mesh anode. Nitrogen gas mixed with pickling solution at 0.4 MPa is sprayed onto the surface of the strip steel.

[0010] Step four, waste liquid regeneration and metal recovery, recovering metals and pickling solution from the waste liquid.

[0011] Furthermore, in step one, the contact pressure between the bristles of the silicon carbide brush roller and the strip steel is 0.05-0.15MPa, the bristle bending amount is ≤10%, the axial oscillation frequency of the silicon carbide brush roller rubbing against the strip steel is 5-8Hz, and the tangential force generated by the circumferential rotation of the brush roller is greater than 3 times the normal force.

[0012] Furthermore, in step one, the efficiency of the silicon carbide brush roller on the strip roller is maintained by the wear amount algorithm. The wear amount algorithm formula is L=L-Δd, W=Δd / t×V, N=N×(1+0.5×W), P=P / (1-0.3×Δd / L);

[0013] Where L is the real-time bristle length, L is the bristle reference length, Δd is the measured wear pit depth, W is the silicon carbide brush roller wear rate, t is the silicon carbide brush roller running time, V is the silicon carbide brush roller linear velocity, N is the compensated brush roller rotation speed, N is the initial rotation speed of the brush roller, P is the compensated brush roller pressure, and P is the initial pressure of the brush roller.

[0014] Furthermore, in step one, the silicon carbide brush roller is divided into 16 independent control zones along the axial direction. The wear amount of each zone is detected independently. If the wear amount of a single zone is greater than 15% of the average value of the adjacent zones, the zone is triggered to reduce its rotation speed by 5% and raise its height by 0.05mm.

[0015] Furthermore, in step one, the silicon carbide brush roller runs for 0-50 hours, the initial acute angle wear of the silicon carbide brush roller is -0.1 mm / h, and the rotational speed of the silicon carbide brush roller is +10%.

[0016] After 50–150 hours of operation, the silicon carbide brush roller exhibits a stable mid-term wear rate of -0.05 mm / h and a downward pressure of +25%.

[0017] After 150–200 hours of operation, the late-stage fatigue wear of the silicon carbide brush roller is -0.15 mm / h, with the brush roller speed increasing by 30% and the pressure increasing by 40%.

[0018] Furthermore, in step two, the pickling solution is prepared with 2.5% HF, 8.0% HNO, 1.5% HEDP, 0.1% thiourea, 0.02% polyether-modified siloxane, and 87.88% HO. The pickling solution is preheated to 55±2℃, and the strip steel is heated to 70-80℃.

[0019] Furthermore, in step three, the pickling interface temperature of the strip steel is 80-90℃, and a square wave pulse current with a peak value of 3A / dm is applied to the titanium mesh anode. 2 Duty cycle 30%, frequency 200Hz.

[0020] Furthermore, in step four, chromium is recovered from the waste liquid through BDD electrode electrolysis, and molybdenum is recovered through ionic liquid extraction; HNO is recovered from the bipolar membrane electrodialysis waste liquid.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] (1) The silicon carbide brush roller achieves flexible contact and rigid removal of the oxide layer on the surface of the strip steel. Combined with the dynamic adjustment of the rotation speed and pressure of the silicon carbide brush roller, and the sweeping-shearing composite mode of the silicon carbide brush roller motion trajectory, the strip steel processing speed reaches 20mpm, which significantly improves the removal efficiency of the oxide layer on the surface of the strip steel, and at the same time, the life of the silicon carbide brush roller is increased to 200 hours.

[0023] (2) The pickling method of strip steel is eddy current heating-pulse microcurrent coupling, which compresses the effective reaction time to 0.5 seconds, resulting in a high oxide layer removal rate and effectively reducing the residual oxide layer on the surface of the strip steel.

[0024] (3) Thiourea, HEDP and wetting agent accelerate the dissolution rate of Cr and Mo oxides in pickling solution, making it easier to recover Cr and Mo, reducing iron loss of strip steel substrate. Bipolar membrane electrodialysis treats pickling solution and recovers HNO to be directly reused in pickling tank, achieving zero waste liquid discharge and making it more environmentally friendly. Attached Figure Description

[0025] Figure 1 This is a process flow diagram of the present invention; Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] Please see Figure 1 The present invention provides a technical solution: a continuous strip steel processing process based on silicon carbide brush roller activation and high-speed pickling, for use in super duplex stainless steel 2507 strip steel or for duplex steel and its high Cr / MO / Ni ultra-corrosion resistant stainless steel.

[0029] Step 1: Re-grind and pre-activate the silicon carbide brush roller (hereinafter referred to as the brush roller), and process the super duplex stainless steel 2507 strip (hereinafter referred to as the strip) at a speed of 20mpm;

[0030] Equipment and parameters

[0031] Brush roller structure: silicon carbide bristles (diameter 0.15-0.2mm, density 120-150 bristles / cm²) 2 The brush roller diameter is 300-400mm, and the rotation speed is 800-1200rpm.

[0032] Contact pressure between brush bristles and strip steel: 0.05-0.15MPa (pressure closed-loop control), brush bristle bending amount ≤10%;

[0033] Dynamic compensation: The laser rangefinder monitors the brush filament length in real time, and automatically adjusts the distance between the brush roller and the strip when the wear is greater than 10%.

[0034] Silicon carbide bristles use a "sweeping-shearing" combined action to peel off the oxide layer, avoiding scratches on the steel strip substrate (surface roughness Ra 0.5-0.8μm);

[0035] The brush bristles are in flexible contact with the strip steel, and the pressure at a single point on the brush bristles is only 0.5-1.2MPa (lower than the yield strength of the strip steel matrix), thus avoiding plastic deformation of the strip steel matrix;

[0036] Pressure closed-loop control: The contact pressure between the brush bristles and the strip steel substrate is 0.05-0.15MPa, and the forced bending amount of the brush bristles is ≤10%, forming elastic contact (non-rigid scraping);

[0037] Sweeping: The brush roller oscillates axially (frequency 5-8Hz) to disperse the load at a single point;

[0038] Shearing: The circumferential rotation of the brush roller (800-1200 rpm) generates a tangential force that is 3 times greater than the normal force, causing the oxide layer on the surface of the strip steel substrate to be preferentially peeled off brittlely (without cutting the strip steel substrate).

[0039] Step 2: High-speed spraying of gradient pickling solution (contact time ≤ 3 seconds)

[0040] Pickling solution: HF 2.5% + HNO 8% + HEDP 1.5% + thiourea 0.1% + polyether modified siloxane wetting agent 0.02%;

[0041] The following are the matching examples:

[0042] 2.5% HF is used as the core etchant to selectively dissolve chromium / molybdenum oxides (CrO, MoO);

[0043] 8.0% HNO, an iron oxide rust solvent, promotes the loosening of the oxide layer and inhibits hydrogen embrittlement;

[0044] 1.5% HEDP (hydroxyethylidene diphosphonic acid), metal ion chelating agent (complexing Fe) 3+ / Cr 3+ This prevents the formation of a repassivation film.

[0045] Using 0.1% thiourea as a reducing agent, Cr is reduced at high temperature. 6+ Reduced to easily soluble Cr 3+ ;

[0046] 0.02% polyether-modified siloxane, an ultra-low surface tension wetting agent, ensures a wetting angle of <5°, achieving 100% coverage of the strip at a high speed of 20mpm;

[0047] 87.88% of HO was used as a solvent.

[0048] Formula effect

[0049] Improved dissolution selectivity: 0.1% thiourea accelerates the dissolution rate of Cr / Mo oxides, reducing iron loss in the strip matrix;

[0050] Thiourea accelerates the dissolution of CrO and rapidly penetrates the CrO layer before the steel strip substrate is exposed. In addition, it adsorbs and protects the steel strip substrate. Thiourea molecules adsorb on the surface of the steel strip substrate to form a (S=C-NH)-Fe protective film, which blocks the pickling solution from corroding the steel strip substrate.

[0051] Acid mist suppression

[0052] HEDP reduces the HF volatilization rate, ensuring that the HF concentration in the working environment is <1ppm (national standard limit 3ppm).

[0053] This formulation, through the combination of "low acid concentration + highly active additives," ensures the removal rate of the oxide layer while reducing the overall cost of acid washing.

[0054] 2.1 Injection system: Fan-shaped nozzle array (50mm spacing), pressure 2-2.5MPa, covering the entire strip width;

[0055] Temperature control: The pickling solution is preheated to 55±2℃, and the strip surface is eddy current heated to 70-80℃ to increase the reaction rate;

[0056] reaction mechanism

[0057] Thiourea selectively reduces Cr at high temperatures 6+ / Mo 6+ The oxide layer dissolution rate is improved, and the polyether-modified siloxane enables the acid solution to wet with an angle of less than 5° at a velocity of 20 mpm, achieving 100% surface coverage.

[0058] Step 3: Eddy current-microcurrent synergistic strengthening (strip residence time ≤ 0.5 seconds)

[0059] Multiphysics Coupling

[0060] Eddy current heating: A high-frequency induction coil (frequency 50kHz) maintains the pickling interface temperature at 80-90℃, suppressing Fe... 3 +Hydrolysis precipitation;

[0061] Pulsed microcurrent: A square wave pulsed current (peak value 3A / dm) is applied to the titanium mesh anode. 2 (Duty cycle 30%, frequency 200Hz) to promote nanocrystallization of passivation film (grain size <10nm);

[0062] Aerosol stripping: 0.4MPa nitrogen-acid washing solution mixed spray to impact residual oxides;

[0063] Step 4: Online Regeneration of Waste Liquid and Metal Recovery

[0064] Regeneration system

[0065] Electrochemical oxidation: The waste liquid is electrolyzed through a BDD electrode (boron-doped diamond) to remove Cr. 3 +Oxidation to Cr 6+ Post-selective adsorption;

[0066] Acidity regeneration: Bipolar membrane electrodialysis (40V) separation of H+ + With NO3 - H + Reuse rate ≥ 95%;

[0067] Mo recovery: MoO4 enrichment by ionic liquid extraction ([BMIM]PF) 2- Electrolytic reduction yields metallic molybdenum powder;

[0068] After treatment, the liquid discharge rate is ≤0.5%, and all components are converted into reusable raw materials or compliant solid waste.

[0069] Implementation

[0070] Acid regeneration (H + Recycling ≥95%

[0071] Bipolar membrane electrodialysis: Electrolytic separation of H from waste acid washing solution + / OH - →Regenerated HNO is directly reused in the pickling tank.

[0072] Metal resource recovery (Cr / Mo recycling)

[0073] Chromium: Chelating resin adsorbs Cr 3+ →Electrolytic reduction to metallic chromium ingots;

[0074] Molybdenum: Extracted from MoO4 using organic solvents 2- →Ammonia water is back-extracted to produce ammonium molybdate crystals;

[0075] Residue solidification

[0076] Calcium fluoride sludge → sintered into artificial fluorite (metallurgical auxiliary material);

[0077] Iron-containing sludge → magnetic separation into iron concentrate

[0078] Wastewater is evaporated and crystallized into industrial salt (NaCl);

[0079] The essence of recycling: molecular disassembly (electrochemical / chemical method) → targeted element recovery → high-temperature phase transformation of residues into commodities, achieving zero discharge of waste liquid and full conversion into resources.

[0080] Example 2

[0081] Experimental subject: Super duplex stainless steel 2507 strip (width 1500mm, thickness 2.5mm, oxide layer thickness 25μm), continuous processing speed 20mpm.

[0082] 1. Re-grinding: Brush roller (brush filament diameter 0.18mm, rotation speed 1000rpm, pressure 0.1MPa), oxide layer residue ≤3μm;

[0083] 2. Pickling solution: HF 2.5% + HNO 8% + composite additive (HEDP), spray pressure 2.2MPa, contact time 2.5 seconds;

[0084] 3. Multi-field coupling: Eddy current heating temperature 85℃, pulse current 3A / dm 2 ;

[0085] 4. Waste liquid regeneration: H + Reuse, Mo recovery, Cr recovery.

[0086] result:

[0087] Surface quality: Ra = 0.4 μm, no oxide scale residue, passivation film is uniform and dense (XPS detection Cr / Fe ratio > 2.5);

[0088] Efficiency comparison: Pickling speed 20mpm (traditional process 5mpm), unit capacity increased by 400%;

[0089] Brush roller life: The dynamic wear compensation technology of the brush roller allows for continuous operation for 200 hours with a bristle wear of <8%, eliminating the need for replacement, based on the process requirement of ≥98% iron oxide scale removal.

[0090] Dynamic wear compensation technology: When the brush roller brushes at high speed (20mpm), the wear of the brush bristles causes fluctuations in contact force (±30%). The lifespan of traditional brush rollers is <100 hours. This embodiment extends the lifespan of the brush bristles by real-time wear feedback and dual closed-loop control of pressure / speed.

[0091] 1. Laser-based online wear monitoring

[0092] Hardware configuration: High frame rate laser displacement sensors (1μm accuracy, 500Hz sampling rate) are deployed on both sides of the brush roller;

[0093] The laser displacement sensor scanning range covers the effective wear area of ​​the brush bristles (50-120mm from the base);

[0094] Wear calculation algorithm: Real-time bristle length L = reference length L - wear pit depth Δd measured by laser, wear rate W = (Δd / running time t) × linear velocity V.

[0095] 2. Bivariate Compensation Execution System

[0096] Bivariate compensation execution data table, Table 1

[0097]

[0098] Where N is the compensated brush roller speed, N is the initial brush roller speed, W is the brush roller wear rate, P is the compensated brush roller pressure, P is the initial brush roller pressure, Δd is the wear pit depth, and L is the brush bristle reference length.

[0099] 3. Wear leveling control (anti-uneven wear)

[0100] Partition compensation logic

[0101] The brush roller is divided into 16 independent control zones along the axial direction → the wear amount of each zone is detected independently;

[0102] If the wear in a single zone is greater than 15% of the average wear in adjacent zones, then the speed in that zone will be reduced by 5% and the speed will be increased by 0.05mm.

[0103] Path to achieving a 200-hour lifespan:

[0104] Wear-compensation correspondence table, Table 2

[0105]

[0106] End of life determination criteria

[0107] The residual length of the bristles in a single zone is less than 45mm (original 100mm);

[0108] The contact force fluctuation after compensation is > ±20%;

[0109] Abnormal surface quality (Ra value increases > 0.5 μm).

[0110] Comparative example (traditional belt abrasive grinding + acid washing):

[0111] 1. Belt grinding: P400 abrasive belt, linear speed 20m / s, pressure 0.3MPa, oxide layer residue 12μm;

[0112] 2. Pickling solution: HF 10% + HNO 25%, immersion treatment speed 5 mpm;

[0113] Results: Ra = 3.2 μm, microcracks at the edge of the strip (depth 5 μm), and waste liquid treatment cost was 4.8 times that of Example 2.

[0114] Comparison table of Example 2 and Comparative Example, Table 3

[0115]

[0116] The process for detecting microcracks at the edge of steel strip is as follows: The detection equipment is a laser profile scanner, which detects the crack depth online. The laser profile scanner is placed 2-3 meters behind the pickling section exit (to avoid droplet interference).

[0117] Crack depth calculation process

[0118] 1. Laser scan the flat surface → record the reference height H;

[0119] 2. Scan the cracked area → Measure the height H of the lowest point of the pit;

[0120] 3. Depth h = |HH|, (accuracy ±0.2μm, capable of identifying cracks ≥1μm).

[0121] The cost of waste liquid treatment is 4.8 times that of Example 2, calculated as follows:

[0122] (1) Increased amount of HF neutralizing reagent

[0123] Low concentration (2.5% HF) requires 1.8 tons of Ca(OH)2 → high concentration (10% HF) requires 7.2 tons of Ca(OH);

[0124] (2) Increased calcium fluoride sludge volume leads to higher treatment costs.

[0125] Low concentration: only 0.8 tons of sludge → High concentration: up to 4.1 tons of sludge;

[0126] (3) Increased the cost of nitrate denitrification

[0127] Low concentration: NO3 - Not exceeding the standard → High concentration: NO3 - 25000 mg / L (exceeds the national standard by 2.5 times, requiring denitrification treatment);

[0128] 4. Total Cost Accounting

[0129] The cost of the low-concentration process is $556, and the cost of the high-concentration process is $2569. The ratio of the high-concentration process cost of $2569 to the low-concentration process cost of $556 is 4.62. The ratio of 4.62 to the engineering margin is adjusted to 4.8.

[0130] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling, characterized in that, Includes the following steps: Step 1: Strip surface treatment. The strip is re-grinded and pre-activated by silicon carbide brush rollers at a speed of 20 mpm. The brush filament length is monitored in real time by a laser rangefinder. When the brush filament wear is greater than 10%, the distance between the silicon carbide brush rollers and the strip is adjusted. Step 2: Gradient pickling solution spraying. The pickling solution components include HF, HNO, HEDP, thiourea, polyether modified siloxane wetting agent, and HO. The pickling solution is sprayed through a fan-shaped nozzle array at a spraying pressure of 2-2.5 MPa, covering the entire strip surface. The contact time between the pickling solution and the strip is ≤3 seconds. Step 3: Eddy current-microcurrent treatment of the strip steel. The pickling interface temperature of the strip steel is maintained by a high-frequency induction coil. A square wave pulse current is applied to the strip steel by the titanium mesh anode. Nitrogen gas mixed with pickling solution at 0.4 MPa is sprayed onto the surface of the strip steel. Step four, waste liquid regeneration and metal recovery, recovering metals and pickling solution from the waste liquid.

2. The continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling according to claim 1, characterized in that: In step one, the contact pressure between the bristles of the silicon carbide brush roller and the strip steel is 0.05-0.15 MPa, and the bristle bending amount is ≤10%.

3. The continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling according to claim 1, characterized in that: In step one, the axial oscillation frequency of the silicon carbide brush roller when rubbing the strip is 5-8 Hz, and the tangential force generated by the circumferential rotation of the brush roller is more than 3 times the normal force.

4. The continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling according to claim 1, characterized in that: In step one, the efficiency of the silicon carbide brush roller on the strip roller is maintained by the wear amount algorithm. The wear amount algorithm formula is L=L-Δd, W=Δd / t×V, N=N×(1+0.5×W), P=P / (1-0.3×Δd / L); Where L is the real-time bristle length, L is the bristle reference length, Δd is the measured wear pit depth, W is the silicon carbide brush roller wear rate, t is the silicon carbide brush roller running time, V is the silicon carbide brush roller linear velocity, N is the compensated brush roller rotation speed, N is the initial rotation speed of the brush roller, P is the compensated brush roller pressure, and P is the initial pressure of the brush roller.

5. The continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling according to claim 1, characterized in that: In step one, the silicon carbide brush roller is divided into 16 independent control zones along the axial direction. The wear amount of each zone is detected independently. If the wear amount of a single zone is greater than 15% of the average value of the adjacent zones, the zone is triggered to reduce its rotation speed by 5% and raise its height by 0.05mm.

6. The continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling according to claim 1, characterized in that: In step one, the silicon carbide brush roller runs for 0-50 hours, the initial sharp angle wear of the silicon carbide brush roller is -0.1 mm / h, and the speed of the silicon carbide brush roller is +10%. After 50–150 hours of operation, the silicon carbide brush roller exhibits a stable mid-term wear rate of -0.05 mm / h and a downward pressure of +25%. After 150–200 hours of operation, the late-stage fatigue wear of the silicon carbide brush roller is -0.15 mm / h, with the brush roller speed increasing by 30% and the pressure increasing by 40%.

7. The continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling according to claim 1, characterized in that: In step two, the pickling solution is prepared with the following proportions: 2.5% HF, 8.0% HNO, 1.5% HEDP, 0.1% thiourea, 0.02% polyether-modified siloxane, and 87.88% HO.

8. The continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling according to claim 1, characterized in that: In step two, the pickling solution is preheated to 55±2℃, and the strip steel is heated to 70-80℃.

9. The continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling according to claim 1, characterized in that: In step three, the pickling interface temperature of the strip steel is 80-90℃, and a square wave pulse current with a peak value of 3A / dm is applied to the titanium mesh anode. 2 Duty cycle 30%, frequency 200Hz.

10. The continuous strip steel processing technology based on silicon carbide brush roller activation and high-speed pickling according to claim 1, characterized in that: In step four, chromium is recovered from the waste liquid by electrolysis using a BDD electrode, and molybdenum is recovered by extraction using an ionic liquid; HNO is recovered from the waste liquid obtained by bipolar membrane electrodialysis.

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