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CN-122013289-A - Green plate and strip dephosphorization process using pulse current

CN122013289ACN 122013289 ACN122013289 ACN 122013289ACN-122013289-A

Abstract

The invention relates to the technical field of plate and strip dephosphorization, in particular to a plate and strip green dephosphorization process using pulse current; A green dephosphorization process for a plate strip by using pulse current is to realize the efficient stripping and resource utilization of the oxide skin on the surface of the plate strip through strip steel uncoiling pretreatment, ultrasonic cavitation presplitting, aerosol seed crystal activation, pulse current electrolysis, flushing separation and drying recovery; the invention provides a green plate-strip dephosphorization process using pulse current, which greatly reduces electrolytic load through the synergistic effect of ultrasonic cavitation pre-cracking and aerosol seed crystal activation, peels off oxide skin by using pulse current in a conducting period, induces iron and phosphorus in-situ precipitation in a turn-off period, synchronously realizes efficient dephosphorization and recycling of iron phosphate byproducts, systematically solves the industrial problems of high energy consumption, quick accumulation of electrolyte iron ions and low byproduct value of the traditional electrolytic dephosphorization process, and provides a new green dephosphorization strategy with low energy consumption, near zero emission and high benefit for steel surface treatment.

Inventors

  • YU ZHU
  • ZHANG MENG
  • WEI LICHUAN

Assignees

  • 北京众联鑫旺科技有限公司

Dates

Publication Date
20260512
Application Date
20260305

Claims (9)

  1. 1. A green plate strip dephosphorization process using pulse current is characterized in that high-efficiency stripping and recycling of oxide skin on the surface of a plate strip are realized through strip steel uncoiling pretreatment, ultrasonic cavitation presplitting, aerosol seed crystal activation, pulse current electrolysis, flushing separation and drying recovery.
  2. 2. A green dephosphorization process for a plate strip using a pulse current according to claim 1, comprising the steps of: The method comprises the steps of S1, strip steel uncoiling pretreatment, namely, installing a strip steel coil on an uncoiler, uncoiling the strip steel coil by the uncoiler, feeding the strip steel coil into a straightener, setting the straightening speed to be 10-20m/min, setting the number of straightening rollers to be 6-9, setting the diameter of the straightening rollers to be 50-80mm, flattening the strip steel, enabling the straightened strip steel to enter an alkaline washing tank to stay for 30-45min, setting the temperature of the alkaline washing tank to be 55-60 ℃, filling 10% sodium carbonate solution into the alkaline washing tank, enabling the filling amount to be 70% of the volume of the alkaline washing tank, enabling the strip steel to enter a pre-flushing tank after the strip steel stays, and adopting normal-temperature clean water with the pressure of 5MPa to perform three-stage countercurrent flushing to clear residual sodium carbonate solution, thus obtaining clean strip steel; S2, ultrasonic cavitation presplitting, namely feeding clean strip steel into a closed ultrasonic cavitation cavity, filling an aqueous medium in the cavity, starting a multi-frequency composite ultrasonic generator, setting the composite frequency of ultrasonic frequency to 20kHz, 40kHz and 80kHz, wherein the ultrasonic power density is 4-5W/cm 2 , the presplitting treatment time is the running time of the strip steel passing through the cavity, the running speed of the strip steel is 0.2-0.5m/S, the pretreatment time is controlled to be 8-12S by adjusting the speed of the strip steel, and the presplitting strip steel is obtained after the treatment is completed; S3, aerosol seed crystal activation, namely feeding the presplitting strip steel into a closed aerosol spray chamber, uniformly spraying aerosol activation liquid on the surface of the strip steel by adopting an atomization nozzle in a form of mist droplets with the diameter of 20um to form an extremely thin activation liquid film, wherein the spraying flow is 100ml/m 2 , the running speed of the strip steel is 20m/min, and the activation strip steel is obtained after the spraying is completed; S4, pulse current electrolysis, namely continuously passing activated strip steel through two electrolytic tanks which are connected in series, wherein a cathode plate and an anode plate are arranged in the electrolytic tanks, the anode plate is made of titanium coated lead dioxide, the cathode plate is made of stainless steel, the distance between the electrode plates is set to be 50-100mm, electrolyte is arranged in the electrolytic tanks, then a pulse power supply is started, pulse current parameters are set to be current density of 30-40A/dm 2 , pulse frequency of 600-800Hz, duty ratio of 25-40%, positive and negative pulses are adjustable, single-tank electrolysis time is 12-15S, total electrolysis time is 24-30S, strip steel running speed is 20-30m/min, the length of a single electrolytic tank is 8m, and dephosphorization strip steel and electrolyte containing sediment are obtained after electrolysis is completed; S5, flushing and separating, namely conveying the dephosphorization strip steel into a high-pressure water flushing device, flushing with high-pressure water of 15MPa, thoroughly removing oxide skin fragments and residual sediments falling off the surface of the strip steel, flushing to obtain clean dephosphorization strip steel, combining and collecting wastewater generated by the high-pressure water flushing and electrolyte containing sediments, conveying the wastewater and the electrolyte containing sediments to a hydrocyclone, carrying out solid-liquid separation, setting the separation granularity of the hydrocyclone to be 8um, and separating to obtain supernatant and an iron-phosphorus precipitation filter cake; S6, drying and recycling, namely feeding the clean dephosphorization strip steel into a hot air dryer, setting the drying temperature to be 80-120 ℃, setting the air speed to be 10-15m/S, drying to remove water on the surface of the strip steel, rolling the dried strip steel by a coiling machine, wherein the coiling speed is 10-60m/min, the maximum coiling diameter is 1800-2200mm, obtaining a finished product of the phosphorus-free strip steel, supplementing sodium sulfate into the obtained supernatant to adjust the concentration of sodium sulfate to be 10%, then refluxing the supernatant to an electrolytic tank for recycling as electrolyte, settling and separating the obtained iron-phosphorus precipitate filter cakes, collecting the obtained iron phosphate powder, the iron phosphate hydroxide powder and the iron oxide powder, and packaging the obtained iron phosphate powder and the iron oxide powder respectively for later use.
  3. 3. The green dephosphorization process for plate strip using pulse current according to claim 2, wherein the sedimentation separation and collection in step S6 comprises the steps of: A1, transferring the obtained iron-phosphorus precipitate filter cake into a spray drying tower, setting a drying temperature to be 150-200 ℃, drying for 30min, transferring into a grinder after finishing drying, grinding for 15min, transferring into an air classifier after finishing grinding, setting the rotating speed of a classifying wheel to be 1000rpm, and air source pressure to be 0.5MPa, separating and collecting iron phosphate by utilizing particle size difference, packaging by using a vacuum packaging machine and a moisture-proof aluminum foil bag, and warehousing to obtain iron phosphate and residual coarse powder materials; A2, transferring the residual coarse powder materials to a gravity separator, wherein the gravity separator is set to have a vibration frequency of 30Hz and a wind speed of 2.5m/s, and separating out the iron hydroxyphosphate by utilizing the density difference to obtain the iron hydroxyphosphate and residual heavy materials; A3, transferring the residual heavy materials to a wet electromagnetic separator, setting the magnetic field strength to be 1.5 Mo Gaosi and the pulp flow rate to be 0.5m 3 /h, separating by utilizing magnetic difference to obtain ferric oxide powder, and packaging by using a vacuum packaging machine and a woven bag and warehousing.
  4. 4. The green dephosphorization process for a plate strip using a pulse current according to claim 2, wherein the preparation method of the aerosol activation liquid in the step S3 comprises the following steps: b1, accurately weighing citric acid, placing the citric acid in a stainless steel batching tank, adding deionized water, starting a batching tank stirrer, setting the rotating speed to 300rpm, and continuously stirring for 15min at room temperature to obtain an organic acid base solution; adding iron hydroxy phosphate powder into a grinder, setting the grinding particle size to be 2um, grinding for 15min to obtain seed crystal powder, adding the seed crystal powder into the organic acid base solution, starting a batching tank stirrer, adjusting the rotating speed to 400rpm, and continuously stirring and dispersing for 30min at room temperature to uniformly suspend the seed crystal powder in the organic acid base solution to obtain seed crystal suspension; And B3, filtering the seed crystal suspension through a 100-mesh filter screen, removing agglomerated particles, transferring the seed crystal suspension into a liquid storage tank of an aerosol generating device, sealing and preserving for standby, and maintaining a low-speed stirring device of the liquid storage tank at a speed of 100rpm to prevent the seed crystal from settling in a standing process and maintain the concentration of the suspension to be uniform and stable, thereby obtaining the aerosol activated liquid.
  5. 5. The green dephosphorization process for a plate strip using a pulse current according to claim 2, wherein the preparation method of the electrolyte in the step S4 comprises the following steps: Accurately weighing sodium sulfate, placing the sodium sulfate into an anti-corrosion liquid preparation tank, adding deionized water, starting a liquid preparation tank stirrer, setting the rotating speed to 300rpm, and continuously stirring for 20 minutes at room temperature until the sodium sulfate is completely dissolved, and obtaining a sodium sulfate solution; Slowly adding sodium dihydrogen phosphate into the sodium sulfate solution, starting a stirrer, keeping the rotating speed at 300rpm, and continuously stirring for 10min to completely dissolve the sodium dihydrogen phosphate and fully mixing the sodium dihydrogen phosphate with the sodium sulfate solution to obtain electrolyte base solution; And C3, filtering the electrolyte base solution through a 5um precision filter, taking out impurity particles, then conveying the filtered clarified electrolyte to a liquid storage tank of an electrolytic tank circulating system, mixing with the electrolyte circulating in the system, continuously supplying the electrolyte to an electrolytic tank for use through a circulating pump, and in the process of recycling the electrolyte, water is lost due to electrolysis and evaporation, and deionized water and sodium sulfate and sodium dihydrogen phosphate are required to be supplemented every day to keep the composition and concentration of the electrolyte stable.
  6. 6. The green phosphorus removal process for a green sheet using a pulse current according to claim 4, wherein the mass ratio of citric acid to deionized water in the step B1 is 1:50.
  7. 7. The green phosphorus removal process for a green sheet using a pulse current according to claim 4, wherein the mass ratio of the seed powder to the organic acid based liquid in the step B2 is 1:50.
  8. 8. The green phosphorus removal process for a plate strip using a pulsed current of claim 5, wherein the mass ratio of sodium sulfate to deionized water in step C1 is 1:10.
  9. 9. The green phosphorus removal process for a green sheet using a pulse current according to claim 5, wherein the mass ratio of the potassium dihydrogen phosphate to the sodium sulfate solution in the step C2 is 1:200.

Description

Green plate and strip dephosphorization process using pulse current Technical Field The invention relates to the technical field of plate and strip dephosphorization, in particular to a green plate and strip dephosphorization process using pulse current. Background In the contemporary ferrous metallurgy and processing industry, efficient removal of dense oxide skin on the surface of hot rolled strip is evolving as a key bottleneck restricting the green transformation of high quality steel surface treatment. The traditional chemical pickling dephosphorization process relies on the chemical dissolution of strong acid to the oxide skin, and the single etching mode based on the strong corrosive medium has inherent defects, so that acid pickling not only generates a large amount of acid-containing waste liquid and dangerous waste sludge to cause serious environmental pollution and high treatment cost, but also seriously influences the surface quality of the product due to the over-corrosion and hydrogen embrittlement risks of the steel matrix by the acid liquor, and the iron resources in the oxide skin are completely converted into low-value solid wastes, so that the comprehensive production cost is high. Even more troublesome, as environmental policies become more stringent, the survival space of pickling processes is being drastically compressed, so that this traditional process is excluded from sustainable manufacturing schemes. In recent years, researchers have attempted to introduce electrolytic dephosphorylation techniques into the field of surface treatment of sheet strips in an effort to achieve acid-free clean production. However, the prior art scheme is still limited to using direct current electrolysis as a single driving force, and electrolyte is only used as a conductive medium, so that the pretreatment load-reducing design of an oxide scale structure and a resource utilization way of dissolved iron ions are lacked, and core defects of high energy consumption, low efficiency, frequent discharge caused by rapid accumulation of the electrolyte iron ions and the like exist under the conditions of thick oxide scale and high-speed production line. Therefore, how to construct a multi-field cooperative pretreatment-electrolysis coupling system, and realize in-situ precipitation and recycling recovery of iron ions while efficiently peeling oxide skin, has become a core technical bottleneck to be broken through in the green dephosphorization field of the steel industry. The present invention provides a solution to the above problems. Disclosure of Invention The invention aims to provide a green dephosphorization process for a plate belt by using pulse current, which can effectively strip oxide skin on the surface of the plate belt. The green plate strip dephosphorization process using pulse current realizes efficient stripping and resource utilization of the surface oxide skin of the plate strip by strip steel uncoiling pretreatment, ultrasonic cavitation presplitting, aerosol seed crystal activation, pulse current electrolysis, flushing separation and drying recovery. The green plate strip dephosphorization process using pulse current comprises the following steps: The method comprises the steps of S1, strip steel uncoiling pretreatment, namely, installing a strip steel coil on an uncoiler, uncoiling the strip steel coil by the uncoiler, feeding the strip steel coil into a straightener, setting the straightening speed to be 10-20m/min, setting the number of straightening rollers to be 6-9, setting the diameter of the straightening rollers to be 50-80mm, flattening the strip steel, enabling the straightened strip steel to enter an alkaline washing tank to stay for 30-45min, setting the temperature of the alkaline washing tank to be 55-60 ℃, filling 10% sodium carbonate solution into the alkaline washing tank, enabling the filling amount to be 70% of the volume of the alkaline washing tank, enabling the strip steel to enter a pre-flushing tank after the strip steel stays, and adopting normal-temperature clean water with the pressure of 5MPa to perform three-stage countercurrent flushing to clear residual sodium carbonate solution, thus obtaining clean strip steel; S2, ultrasonic cavitation presplitting, namely feeding clean strip steel into a closed ultrasonic cavitation cavity, filling an aqueous medium in the cavity, starting a multi-frequency composite ultrasonic generator, setting the composite frequency of ultrasonic frequency to 20kHz, 40kHz and 80kHz, wherein the ultrasonic power density is 4-5W/cm 2, the presplitting treatment time is the running time of the strip steel passing through the cavity, the running speed of the strip steel is 0.2-0.5m/S, the pretreatment time is controlled to be 8-12S by adjusting the speed of the strip steel, and the presplitting strip steel is obtained after the treatment is completed; S3, aerosol seed crystal activation, namely feeding the presplitting strip steel into a