Nano-catalysis acid-free rust removal circulating equipment and method for heat treatment of metal parts

Abstract

The invention provides nano-catalysis acid-free rust removal circulating equipment for heat treatment of metal parts, which comprises a nano-catalysis rust removal reaction unit, a heat treatment unit, a heat treatment unit and a heat treatment unit, and is characterized in that the nano-catalysis rust removal reaction unit comprises a reaction tank for containing a neutral nano-catalysis working solution; the working solution comprises a nano-catalyst serving as a catalytic activity center and an oxidizing agent or a complexing agent which has a synergistic effect with the nano-catalyst, a regulation and control mechanism for maintaining the reaction temperature and the uniform dispersion of the catalyst is arranged in the reaction tank; the circulating purification and regeneration unit is connected with the reaction tank through a pipeline to form a closed loop; the unit comprises a multi-stage filtration device for online removal of reaction byproducts, and a regeneration device for online maintenance or recovery of the activity of the nano-catalyst. The whole process chain is completed under a neutral condition, acid mist and strong acid wastewater are avoided, and real green manufacturing is realized.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, specifically to an environmentally friendly, efficient, and resource-recycling rust removal device and method for removing oxide scale from the surface of heat-treated metal workpieces (such as screws, springs, and other standard parts). Background Technology

[0002] After annealing heat treatment, standard metal parts such as screws will form a dense oxide scale (mainly Fe3O4 and Fe2O3) on their surface. Traditional mainstream processes use strong acids such as hydrochloric acid and sulfuric acid for pickling. This method causes significant environmental pollution, generating acid mist and wastewater containing heavy metals, posing a risk of corrosion to the workpiece substrate, and operating in a harsh environment.

[0003] Chinese patent application publication number CN109940503A discloses a method for degreasing and removing rust from steel structural components. The first step of this method involves immersing the steel structural components in a degreasing tank equipped with a turbulent flow device. The slurry in the degreasing tank consists of water and abrasive particles. The second step involves introducing the expired degreasing slurry into the rust removal tank, adding an acidic solution to maintain the pH value between 9 and 11, and stirring and soaking for 10-30 minutes to dissolve the rust in the slurry. Finally, the slurry with dissolved rust is subjected to solid-liquid separation using a centrifugal separator. The separated solid abrasive particles are then returned to the degreasing tank for reuse. This invention achieves the removal of most grease and rust from steel structural components using physical action, reducing the amount of acid and alkali used in the pretreatment process of hot-dip galvanizing, reducing water pollution, and reducing the pressure on subsequent wastewater treatment. However, this prior art has the following inherent drawbacks:

[0004] 1. Limitations of rust removal mechanism: Its core is physical mechanical scraping. It has a low removal efficiency for the dense and firm oxide layer formed after annealing, and is prone to uneven treatment or damage to the edges and corners of the workpiece.

[0005] 2. Not truly "acid-free": Its "abrasive regeneration" stage still requires the introduction of acidic solutions to dissolve rust, and it still relies on acid chemistry in essence, failing to get rid of the problem of acid use and subsequent treatment of acid-containing waste liquid.

[0006] 3. Limited media function: Its nanomaterials are only used as mechanical abrasives. After use, they will "fail" due to the adhesion of rust, requiring additional and complex offline acid washing and regeneration steps. The cycle process is long and the system is complex.

[0007] 4. Energy consumption: It mainly relies on turbulent kinetic energy, which has high energy consumption, and does not take into account the energy synergy with the heat treatment process.

[0008] Therefore, there is an urgent need for a truly green and intelligent rust removal technology and equipment that can completely eliminate acidic substances in principle, cause zero damage to workpieces, and enable the working medium to regenerate online efficiently. Summary of the Invention

[0009] The present invention aims to overcome the shortcomings of the prior art and provide an intelligent rust removal circulation device and method based on nanocatalytic chemical action, which is acid-free throughout the process and can realize in-situ regeneration of the catalytic medium.

[0010] A nano-catalytic acid-free rust removal circulating device for heat-treated metal parts includes:

[0011] The nanocatalytic rust removal reaction unit includes a reaction tank for holding a neutral nanocatalytic working fluid; the working fluid contains a nanocatalyst as the catalytic active center, and an oxidant or complexing agent that works synergistically with it; the reaction tank is equipped with a control mechanism for maintaining the reaction temperature and uniform dispersion of the catalyst;

[0012] The circulating purification and regeneration unit is connected to the reaction tank through pipelines to form a closed loop; the unit includes a multi-stage filtration device for online removal of reaction byproducts, and a regeneration device for online maintenance or restoration of the activity of the nanocatalyst.

[0013] The intelligent control unit is used to monitor the chemical state of the working fluid in real time and automatically adjust the operating parameters of the reaction unit and the regeneration unit to maintain the stability and efficiency of the rust removal process.

[0014] Furthermore, the nanocatalyst is a catalytically active nanoparticle, including but not limited to supported nano-titanium dioxide, nano-zero-valent iron, or their magnetic composites; the pH of the working solution is always maintained in the neutral range of 6-8, and the working temperature is 60-85℃.

[0015] Furthermore, in the circulating purification and regeneration unit, the regeneration device is a physical separator or a chemical regeneration device, used to separate the nanocatalyst from the working fluid and restore its surface activity. The physical separator is preferably a high-gradient magnetic separation separator designed for magnetic nanocatalysts.

[0016] Furthermore, the device also includes a heat recovery module for capturing the residual heat of the workpiece to be processed (such as screws that have just been annealed) to preheat the neutral nanocatalytic working fluid.

[0017] Furthermore, the intelligent control unit includes a pH sensor, a redox potential sensor, and a dosing system that automatically controls the addition of oxidants, pH adjusters, or dispersants based on sensor data.

[0018] The present invention also provides a rust removal method based on the above-mentioned equipment, comprising the following steps:

[0019] S1: The heat-treated metal workpiece is immersed in a neutral nano-catalytic working solution. Under the catalytic action, the oxide scale on the surface of the workpiece is chemically reduced or complexed and peeled off.

[0020] S2: The working fluid is continuously passed through the circulation purification and regeneration unit. Without introducing external acidic substances, solid strippings are filtered out and the nano-catalyst is regenerated online to restore the activity of the working fluid.

[0021] S3: Rinse and dry the rust-removed workpiece.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. The use of acid is eliminated at the source. The entire process chain (including the media regeneration process) is completed under neutral conditions (pH 6-8), with no acid mist or strong acid wastewater, achieving true green manufacturing.

[0024] 2. Based on the mild chemical conversion mechanism of nanocatalysis, it can efficiently dissolve dense oxide scale while hardly corroding the metal matrix, maintaining the dimensional accuracy and surface integrity of the workpiece, and overcoming the wear or deformation that may be caused by physical scratching.

[0025] 3. The core of this invention is the regeneration of "catalytic activity," rather than the simple recycling of "solid abrasive." Through online separation and regeneration (such as magnetic recovery and surface reduction), the nanocatalyst, as a "consumable," can be used repeatedly and for a long time, and the main body of the working fluid can be circulated for a long time, resulting in extremely low operating costs. This is simpler and more economical than the "abrasive-acid washing regeneration" process.

[0026] 4. Online monitoring and automatic control ensure that the catalytic reaction is always in optimal condition. In particular, the heat recovery module effectively utilizes the residual heat from workpiece annealing, significantly reducing system energy consumption compared to purely physical flushing or external heating methods.

[0027] This invention is particularly suitable for the continuous and automated production of large batches of small-sized heat-treated workpieces such as screws and springs. It is easy to integrate with upstream and downstream processes (annealing, passivation) to form a green production line. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the system structure of the present invention. Detailed Implementation

[0029] To further understand the features, technical means, and specific objectives and functions achieved by the present invention, the present invention will be described in further detail below with reference to specific embodiments and accompanying drawings.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] like Figure 1 As shown;

[0032] First implementation method:

[0033] Annealed screws (temperature approximately 200-300℃) are fed into the system via an automatic feeding mechanism. The residual heat they carry is recovered in the feeding section and used to preheat the system's working fluid. The screws then enter the corrosion-resistant reaction tank.

[0034] The tank is filled with a neutral nanocatalytic working solution. For example, a deionized water-based solution is used, with the addition of 1.0 g / L sodium citrate-modified magnetic nano-zero-valent iron as a catalyst and 1.5% hydrogen peroxide (H2O2). At 65-75℃ (maintained by a heating system with residual heat) and neutral pH, the nano-zero-valent iron and H2O2 form a Fenton-like catalytic system, which can gently convert the solid Fe3O4 oxide scale into soluble or loose iron ions / complexes without corroding the steel matrix of the screw.

[0035] The working fluid containing shed material and catalyst is pumped to the circulating purification and regeneration unit. First, large particles are removed by a primary filter (e.g., a 100-mesh sieve). Then, the working fluid flows through a high-gradient magnetic separator, where the powerful magnetic force captures and recovers almost all of the magnetic nanocatalyst Fe@C. The recovered catalyst can be easily regenerated by air oxidation and then directly returned to the reaction tank. This process requires no acidic solution whatsoever.

[0036] The clarified liquid, after magnetic separation, is then passed through a precision filter (e.g., 5μm) to remove non-magnetic fine particles. An online monitoring system continuously monitors the ORP (oxidation-reduction potential) and pH of the clarified liquid. When the ORP value decreases (indicating H2O2 depletion), H2O2 is automatically replenished; when the pH deviates, dilute alkali or a weak acid adjuster is automatically added to maintain neutrality. The purified clarified liquid is then returned to the reaction tank.

[0037] After rust removal, the screws are rinsed and dried before being shipped out. The entire process is fully automated and controlled by a PLC.

[0038] Example 2:

[0039] In another preferred embodiment, a non-magnetic but easily filterable supported nano-TiO2 catalyst is used. In this case, the regeneration device is replaced with a ceramic ultrafiltration membrane module to achieve precise sieving of the catalyst and reaction products. Simultaneously, a low-frequency ultrasonic transducer is integrated into the reaction tank to enhance mass transfer using the cavitation effect, making the catalytic reaction faster and more uniform, especially suitable for workpieces with thick oxide scale.

[0040] Example 3:

[0041] To achieve extreme energy savings, this equipment is directly and sealed to the discharge port of the continuous annealing furnace. High-temperature workpieces enter the reaction tank directly, and their sensible heat can meet most of the heating requirements of the working fluid. The heating and temperature control system only serves as an auxiliary heat preservation system, resulting in overall energy savings of over 60%.

[0042] The above-described embodiments are merely three examples of implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A nano-catalytic acid-free rust removal circulating device for heat-treated metal parts, characterized in that, include: A nanocatalytic reaction unit having a reaction tank for containing a neutral nanocatalytic working solution, the working solution comprising a nanocatalyst and an oxidant or complexing agent; A circulating purification and regeneration unit is connected to the reaction tank to form a working fluid circulation loop; the unit includes a filtration device for separating solid impurities from the used working fluid, and a regeneration device for separating and regenerating the nanocatalyst from the used working fluid. The intelligent control unit is used to monitor the chemical state of the working fluid in real time and automatically adjust the operating parameters of the reaction unit and the regeneration unit to maintain the stability and efficiency of the rust removal process. The nano-catalytic acid-free rust removal circulation equipment is configured to maintain the working fluid in a neutral environment of pH 6-8 throughout the entire rust removal and working fluid regeneration process.

2. The nano-catalytic acid-free rust removal circulating equipment for heat-treated metal parts according to claim 1, characterized in that: The nanocatalyst is a nanoparticle with catalytic oxidation or reduction activity.

3. The nano-catalytic acid-free rust removal circulating equipment for heat-treated metal parts according to claim 1, characterized in that: The nanocatalyst is a magnetic nanocatalyst; the regeneration device is a high-gradient magnetic separator.

4. The nano-catalytic acid-free rust removal circulating equipment for heat-treated metal parts according to claim 1, characterized in that: The circulating purification and regeneration unit also includes an online monitoring and automatic dosing system.

5. The nano-catalytic acid-free rust removal circulating equipment for heat-treated metal parts according to claim 1, characterized in that: The device also includes a heat recovery module, which is located on the feed path.

6. The nano-catalytic acid-free rust removal circulating equipment for heat-treated metal parts according to claim 1, characterized in that: The nanocatalytic reaction unit also includes an ultrasonic generator or a weak electrolysis device.

7. A method for acid-free rust removal of heat-treated metal parts using the nanocatalytic acid-free rust removal circulating equipment according to any one of claims 1-6, characterized in that, Includes the following steps: The metal parts with oxide scale after heat treatment are immersed in the neutral nano-catalytic working solution and a catalytic rust removal reaction is carried out at 60-85℃. The working fluid after the reaction is passed through the circulation purification and regeneration unit to remove solid reaction products and regenerate the nano-catalyst, while maintaining the pH of the working fluid at 6-8. The regenerated working fluid is returned to the reaction tank for recycling.

8. The acid-free rust removal method for heat-treated metal parts according to claim 7, characterized in that: The nanocatalyst is a magnetic nanocatalyst; The regeneration steps in the regeneration unit include: separating the magnetic nanocatalyst from the working fluid using a high-gradient magnetic separation separator, and performing surface regeneration treatment.

9. The acid-free rust removal method for heat-treated metal parts according to claim 7, characterized in that: Before the rust removal reaction, the process also includes a step of preheating the working fluid using the residual heat brought out from the heat treatment process of the metal parts.

10. A nano-catalytic rust removal working fluid, characterized in that, The acid-free rust removal method for heat-treated metal parts according to any one of claims 7-9 comprises deionized water or a neutral salt solution, 0.5-2.0 g / L of nano-catalyst, and 1-3% of hydrogen peroxide or an equivalent complexing agent.

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