A method for removing glass powder from the surface of a high-temperature extruded tail scrap alloy

Abstract

This invention discloses a method for removing glass powder from the surface of alloy residue after high-temperature extrusion, comprising several steps including "residue" collection, preparation, acid pickling and soaking, washing, and surface cleaning. This invention utilizes a controlled ratio of hydrofluoric acid and nitric acid to effectively separate and dissolve the glass powder adhering to the "residue" surface, a first in the industry. Steam heating is used to accelerate the crushing, separation, and corrosion dissolution of the glass powder by leveraging the difference in thermal expansion coefficients between the metal and the glass powder, reducing the soaking time in the acid solution. The chemical removal method reduces the labor intensity of manual glass powder removal and minimizes the safety and environmental hazards of glass powder splashing. By fully utilizing the corrosive properties of hydrofluoric acid on silica, and selecting the acid composition, heating stability, and soaking time based on the steel grade, the method is rationally designed to achieve continuous, stable, and highly efficient removal of glass powder adhering to the "residue" surface, ensuring safety, reliability, environmental friendliness, and practicality.

Description

Technical Field

[0001] This invention relates to the field of residual material disposal in the high-temperature hot extrusion production of seamless steel pipes in industries such as metallurgy and machinery, and specifically to a method for removing glass powder from the alloy surface of the residual material after high-temperature extrusion. Background Technology

[0002] Seamless steel pipes are common metallurgical and steel products, requiring multiple processes from metal smelting and rolling to finished product delivery. The high-temperature hot extrusion method for producing seamless steel pipes (hot extrusion) has become the main method for producing high-end seamless steel pipes both domestically and internationally due to its advantages such as large deformation, ease of one-time forming, high production precision, ease of organizing continuous production, high capacity, and suitability for processing high alloy elements.

[0003] Currently, the commonly used hot extrusion process for seamless steel pipes mainly includes billet preparation (lathe, saw, etc.), billet heating (ring furnace, induction furnace, etc.), billet piercing / expansion, billet descaling, billet reheating, (high-temperature) extrusion, and finished product cooling (cooling bed). High-temperature extrusion involves hydraulically driving a heated high-temperature billet (round steel) through a circular die (extrusion cylinder) to form the pipe. Therefore, the high-temperature extrusion process is the key step in the entire hot extrusion production of seamless steel pipes, directly determining the output and quality of the extruded pipes.

[0004] "Residue" is a metallurgical term published in 2019. The second edition of *Metallurgical Terminology* defines "residue" as "metal remaining in the extrusion cylinder after extrusion." The "residue" produced during the high-temperature extrusion of seamless steel pipes is all alloy material, with a concentric cylindrical structure of unequal diameters (see appendix). Figure 1 The large-diameter section is the tail residue of the tube blank (round steel), and the small-diameter section is the end of the high-temperature extrusion and the tail end after being cut by a hot saw.

[0005] The function of "residue" is as follows: During high-temperature extrusion pipe production, the heated seamless steel pipe blank (round steel) is horizontally driven by the hydraulic cylinder of the extrusion press in the extrusion cylinder. Under the dual constraints of the inner circumferential surface of the outer extrusion cylinder and the outer circumferential surface of the inner extrusion rod, synchronous deformation of diameter change and stretching is achieved. In order to obtain the ideal extrusion effect, a very small portion of the pipe blank (i.e., the tail metal of the pipe blank) is left at the very front of the extrusion cylinder, and this left portion of metal is called "residue".

[0006] Without "pressure residue," the high-temperature extrusion process of seamless steel pipes will result in "tail shrinkage," leading to quality defects in the extruded billet. "Tail shrinkage" refers to a unique funnel-shaped defect that appears at the tail of the extruded product. It occurs in the later stages of the extrusion process, disrupting the density and continuity of the metal and severely affecting the material's properties.

[0007] Therefore, "residue" during the extrusion process is an unavoidable phenomenon. Thus, in the final stage of the extrusion process, a hot saw is used to separate the residue from the extruded seamless steel pipe (extruded rough pipe). The separated residue needs to be recycled and processed as scrap steel in a furnace. However, before recycling the residue, the glass powder coating (film) adhering to its surface needs to be removed.

[0008] Glass powder is composed of powdered silicon dioxide (SiO2), aluminum oxide (Al2O3), titanium dioxide (TiO2), silicates, borates, alkali metal oxides, etc., with silicon dioxide being the main component, typically accounting for over 50%. Silicates improve the chemical stability and high-temperature resistance of glass, borates lower the melting point and increase its fluidity, while alkali metal oxides act as fluxes, lowering the melting point and promoting melting and flow. The molten glass powder not only provides lubrication under high-temperature conditions but also enhances material strength, scratch resistance, and wear resistance. It is usually produced through processes such as high-temperature melting, cooling, and ball milling, and features chemical stability, acid and alkali resistance, and a low coefficient of expansion, meeting the instantaneous melting requirements of seamless steel pipes during high-temperature extrusion.

[0009] Because the tube blanks used in extrusion presses are heated to high temperatures, typically above 1000℃, the combined effect of this heating with the high temperatures generated during metal deformation during extrusion, along with the stringent operating conditions and the requirements for lubrication fluidity at high temperatures, means that ordinary lubricating materials cannot meet the needs of seamless steel tube extrusion deformation. The lubrication condition directly affects the quality and efficiency of hot extrusion of seamless steel tubes. Glass powder, due to its high-temperature lubrication stability and fluidity, is currently widely used in the hot extrusion deformation processing of seamless steel tubes.

[0010] In the production of seamless steel pipes by high-temperature extrusion, the role of glass powder is irreplaceable. Without the lubrication of glass powder, the tube blank is prone to stalling during the extrusion process, and it will also damage the extrusion die, especially causing defects such as tearing, cracking, and end shrinkage on the internal and external surfaces of the tube blank.

[0011] Because fine glass powder cannot be placed directly into the extrusion cylinder, it must be shaped into glass pads for use in the hot extrusion of seamless steel pipes. Different shapes and specifications of glass pads are required depending on the specifications and steel grades needed for production. Each seamless steel pipe extruded requires one glass pad. The glass pad is shattered during extrusion and, under high temperature, sits between the inner wall of the extrusion die and the circumference of the billet, as well as between the extrusion rod and the inner hole of the billet, thus providing lubrication at high temperatures. In other words, a layer of silica coating (film) is applied to the outer circumferential surface of the high-temperature billet. This silica coating (film) must be completely removed before the "extrusion residue" is returned to the furnace; otherwise, it will lead to elemental abnormalities during the smelting process.

[0012] Traditionally, the removal of glass powder adhering to the surface of "residue" is achieved through a physical method, namely, a hammering method. First, the "residue" is fixed in place, then a metal hammer is used to strike the outer surface, removing the adhering glass powder piece by piece. This method can largely remove the glass powder adhering to the "residue," but it still has certain shortcomings, namely:

[0013] 1) High labor intensity: Usually, the "residual glass" is collected after it has cooled naturally. After a certain amount is collected, the outer surface of the "residual glass" is struck with a hammer to break and remove the glass powder one by one. The continuous hammering consumes a lot of physical energy, especially the fatigue in the elbow. The labor intensity of striking in batches is high. Even with multiple people taking turns, the labor intensity cannot be reduced.

[0014] 2) Low work efficiency: The manual hammering operation involves hammering the "residual" surface one by one. The entire operation is done by manpower, which results in low work efficiency. In addition, the outer surface of the "residual" is arc-shaped, making it even more difficult to hammer (the hammer is easy to slip).

[0015] 3) Safety hazards exist: manual hammering is easy to cause fatigue, and glass powder is easy to fly under the impact, posing a mechanical injury safety hazard. The repeated handling of "residual" glass also poses a risk of being hit by objects.

[0016] 4) Environmental hazards: The broken glass powder after being struck will fly randomly and easily adhere to the surface of surrounding objects. Once it adheres again, it is even more difficult to clean up, which poses environmental hazards and affects the work area environment and 6S management.

[0017] In summary, traditional physical removal methods have certain limitations in removing glass powder adhering to the surface of "press residue." However, "press residue" is an inevitable waste product generated during the high-temperature extrusion of seamless steel pipes, and the glass powder adhering to its surface must be removed before it can be recycled into the furnace. Therefore, it is necessary to conduct technical research to improve the traditional methods for removing glass powder from the surface of "press residue."

[0018] However, as a metallurgical production enterprise, the function of pickling is to clean stainless steel and alloy steel products, and it has never been used for the industrial treatment of separating and dissolving glass powder adhering to the metal surface.

[0019] In conclusion, from theory to practice, especially in achieving industrial-scale production capacity, chemical removal methods require targeted technical measures to meet the needs of efficient, environmentally friendly, clean, and safe removal of glass powder adhering to the surface of "pressure residue". Summary of the Invention

[0020] Therefore, the present invention provides a method for removing glass powder from the surface of alloy residue after high-temperature extrusion, so as to solve the technical problems of unsafety and low efficiency caused by traditional physical removal methods.

[0021] The technical solution of the present invention is a method for removing glass powder from the surface of alloy residue after high-temperature extrusion, comprising the following steps: "extrusion residue" collection → work preparation → acid pickling and soaking → cleaning → surface cleaning → inspection and warehousing.

[0022] 1) Collection of “Residual Material”: According to the technical requirements on the production process card, collect the “residual material” after the hot saw has been cut online and cooled to room temperature according to the production batch, and place it in a centralized manner according to steel type and specifications;

[0023] 2) Homework preparation:

[0024] (1) Preparation of “Residue”: Clean the glass powder on the surface of “residue”, remove the glass powder from the surface of “residue”, and transport it to the pickling area in batches;

[0025] (2) Determine pickling parameters

[0026] The acid solution is prepared by mixing hydrofluoric acid solution and nitric acid solution in a mass ratio of 1:2-2.5, and the ratio of the mixed acid of hydrofluoric acid and nitric acid to water is 1:3; in the hydrofluoric acid solution, the volume ratio of hydrofluoric acid to water is 1:2-4; in the nitric acid solution, the volume ratio of nitric acid to water is 1:2-4.

[0027] Determine the acid solution temperature: the acid solution temperature should be 50~70℃;

[0028] 3) Acid washing and soaking:

[0029] The mixed acid solution in the pickling tank is preheated to the set temperature and kept heated during the soaking process to ensure that the temperature of the mixed acid solution meets the set temperature.

[0030] The entire volume is immersed in the solution, with the top surface of the "pressure residue" at least 100 mm below the surface of the acid solution; the immersion time is 2.0 to 4.0 hours.

[0031] 4) Cleaning: After lifting the "residual" acid using a lifting device, the acid solution is fully drained, then sprayed for cleaning, and the water is drained. 5) Surface cleaning: Place each "residual" piece on the cleaning table with the larger diameter cylinder facing down, check the glass powder adhesion on its surface, and if there is adhesion, remove it by tapping.

[0032] The chemical removal method of this invention employs the principle of "pickling" to remove glass powder adhering to the surface of the "pressure residue". Pickling is a common production process in the metallurgical and machinery industries, and is a method of cleaning metal surfaces by using acid solutions to remove oxide scale and rust from steel surfaces. For stainless steel, alloy steel, and other steel products, commonly used pickling acids include hydrofluoric acid (HF), nitric acid (HNO3), and sulfuric acid (H3SO4), among which hydrofluoric acid is the most commonly used.

[0033] Hydrofluoric acid is an aqueous solution of hydrogen fluoride gas. It is a weak acid, a clear, colorless, fuming, corrosive liquid with a strong, pungent odor. It is extremely corrosive, capable of corroding metals, glass, and silicon-containing materials, and is particularly destructive to glass. Hydrofluoric acid can dissolve glass (mainly composed of silicon dioxide), which many other acids cannot dissolve, to form gaseous silicon tetrafluoride. The reaction equation is as follows:

[0034] SiO2(s)+4HF(aq)=SiF4(g)↑+2H2O(l)

[0035] Hydrofluoric acid reacts with silicon and silicon compounds to produce gaseous silicon tetrafluoride, which corrodes glass but has no corrosive effect on plastics, paraffin wax, lead, gold, or platinum. Therefore, based on this principle, glass powder adhering to the surface of the "residue" can be separated by immersing it in a hydrofluoric acid solution.

[0036] Hydrofluoric acid is primarily used for etching in glass engraving, not for full-volume immersion; the two are fundamentally different. Furthermore, hydrofluoric acid is a weak acid, effective at corroding individual glass products, but its corrosive properties are insufficient for metal surfaces, especially alloy surfaces. Therefore, it needs to be mixed with a strong inorganic acid to achieve effective corrosion separation; a combination of hydrofluoric acid and nitric acid is commonly used. Nitric acid, with the chemical formula HNO3, is a strong oxidizing and corrosive monoprotic inorganic acid, and its combination with hydrofluoric acid is suitable for cleaning stainless steel and alloy steel surfaces.

[0037] In step 2), the ratio of hydrofluoric acid to nitric acid can be adjusted appropriately according to the different steel grades, with 1:(2.0~2.5) being appropriate. The acid solution consists of hydrofluoric acid, nitric acid, and water. The (steam) heating temperature is adjusted according to the steel grade, with 50~70℃ being appropriate. Higher alloy content requires a higher temperature, and lower alloy content requires a slightly lower temperature.

[0038] In step 3), a full-volume immersion method is adopted (the temperature of the mixed acid solution has reached the set temperature). Specifically, the "residual steel" is connected by polymer slings (or ropes) according to the steel type and specifications, and then lifted and submerged in the pickling tank using a crane. The ends of the slings (ropes) are fixed to the side rails of the pickling tank. The "residual steel" is then placed flat at the bottom of the pickling tank, with its top surface at least 100mm below the acid solution surface. Depending on the steel type and specifications, the immersion time should be 2.0~4.0 hours. The heating method in step 3) can be steam heating or electric heating. Steam heating requires a heat source, such as a boiler or boiler, which involves a large investment. If the company has waste heat recovery from industrial furnaces, steam heating is an energy-saving and environmentally friendly option. Electric heating has a simple structure, low investment, and is easily adopted by most companies.

[0039] In step 4), a crane is used to vertically lift the "residue" connected by polymer slings (or ropes) as a whole. The crane is suspended for no less than 10 minutes (to drain the acid). The crane then transports the "residue" as a whole to the cleaning platform. The "residue" is then cleaned using factory-made high-pressure water jets for no less than 10 minutes. The water jets are sprayed from the inner holes first, followed by the outer holes, and then back and forth for at least 3 times. After cleaning, the "residue" is lifted by the crane to the cleaning platform and left to stand for no less than 20 minutes to drain the water.

[0040] In step 5), manually remove the polymer slings (or ropes) → place each "pressure residue" on the cleaning table with one end of the large-diameter cylinder facing down → while placing the "pressure residue", check the removal status of the glass powder adhering to its surface → use a wooden hammer to knock away the residual glass powder that has not been corroded and separated and is still attached to the surface of the "pressure residue".

[0041] According to a method for removing glass powder from the surface of alloy residue after high-temperature extrusion, preferably, in step 2), the residue is cleaned manually with a hand hammer.

[0042] Manual hammers are categorized into three types based on the material of the hammerhead: steel, copper, and non-metallic (including wood, polymer plastics, etc.). Steel hammerheads are resistant to deformation and wear, and have a wide range of applications, but they produce sparks when striking other metal objects. Copper hammerheads do not produce sparks and are suitable for explosion-proof environments. Non-metallic hammerheads are lightweight, will not damage the surface of the object being struck, and do not produce sparks.

[0043] Even better, a wooden hammer is used for manual hammering. Wooden hammers are lightweight, making them easy for workers to hammer for extended periods, and the wooden hammerhead, being in contact with the glass powder, offers better safety by preventing splashing compared to a metal hammerhead.

[0044] More preferably, the hand hammer cleaning in step 2) should be performed at a rate of 30 to 60 times per minute.

[0045] According to a method for removing glass powder from the surface of alloy residue after high-temperature extrusion, as per the present invention, preferably, in step 3) pickling immersion, the number of "residues" connected by a single suspension rope does not exceed 30. Pickling immersion quantity: Based on the length of the pickling tank and the length of the polymer suspension strap (rope), it is preferable that the number of "residues" connected by a single suspension strap (rope) does not exceed 30.

[0046] According to a method for removing glass powder from the surface of alloy residue after high-temperature extrusion, as per the present invention, preferably, in the cleaning step 4), the lifting device is a crane; the spray cleaning involves first spraying the inner holes, then spraying the outer surface, and then spraying back and forth for at least three times. The inner holes are prone to accumulating and adsorbing residue, and due to their small diameter, they are difficult to clean; therefore, they are sprayed first. The outer surface is less prone to accumulating and adsorbing residue and is easy to clean; therefore, it is sprayed after the inner holes have been cleaned.

[0047] According to a method for removing glass powder from the surface of alloy residue after high-temperature extrusion, as per the present invention, preferably, the knocking removal in step 5) is performed manually using a hand hammer. More preferably, the knocking removal in step 5) is performed manually using a hand hammer, with a hammering rate of 30-60 times per minute.

[0048] More preferably, the hand hammer in step 5) is a wooden hammer.

[0049] According to a method for removing glass powder from the surface of alloy residue after high-temperature extrusion, preferably, after step 5), the cleaned "extrusion residue" surface is inspected to ensure that there is no glass powder residue before being inspected and stored. The "extrusion residue" confirmed to be free of glass powder residue is placed one by one into a bulk bag (separate bags according to steel type) → the cleaned "extrusion residue" is transported by overhead crane to the machine-side warehouse → information is registered, recorded, and nameplates are affixed.

[0050] According to a method for removing glass powder from the surface of alloy residue after high-temperature extrusion, preferably, in step (2), the acid immersion temperature is at least 40°C higher than the ambient temperature. Taking full account of the ambient temperature, the immersion temperature should preferably be at least 40°C higher than the ambient temperature of the day.

[0051] According to the above process (step) model, the glass powder adhering to the surface of the alloy "extrusion residue" generated in the high-temperature extrusion pipe production of seamless steel pipe can be removed and processed into qualified return steel material, which can meet the process technology requirements of "extrusion residue" remelting.

[0052] This invention provides a method for removing glass powder from the surface of alloy residue after high-temperature extrusion. It is an improvement on the traditional method for removing glass powder adhering to the surface of "compression residue" produced by high-temperature extrusion of seamless steel pipes. Based on the principle of SiO2(s) + 4HF(aq) = SiF4(g)↑ + 2H2O(l), the method consists of six steps: "compression residue" collection → work preparation → acid washing and soaking → cleaning → surface cleaning → inspection and warehousing. The method utilizes a controlled ratio of hydrofluoric acid and nitric acid to effectively separate and dissolve the glass powder adhering to the "compression residue" surface, a first in the industry. Steam heating is used to accelerate the crushing, separation, and corrosion dissolution of the glass powder by utilizing the difference in thermal expansion coefficients between the metal and the glass powder, reducing the soaking time in the acid solution. The chemical removal method reduces the labor intensity of manual hammering to remove glass powder from the source, reduces the safety and environmental hazards of glass powder splashing, and can basically completely replace manual hammering (in case of improper handling during inspection, manual hammering can be used to compensate). This method fully utilizes the corrosive properties of hydrofluoric acid on glass (silicon dioxide). Based on the steel grade, the acid composition, heating stability, and immersion time are selected, resulting in a rationally designed process that effectively removes glass powder adhering to the surface of "pressure residue." It is continuous, stable, highly efficient, safe, reliable, environmentally friendly, practical, and highly effective. Operation is convenient, effectively mitigating occupational health risks. The excellent glass powder removal ensures quality for remelting. It utilizes existing pickling production line equipment, requiring no additional equipment investment, resulting in low cost and easy on-site implementation. Its strong versatility provides valuable reference and application for the removal of glass powder adhering to the surface of "pressure residue" generated during the high-temperature extrusion of seamless steel pipes in the industry.

[0053] Beneficial effects:

[0054] 1. Fully utilizing the corrosive properties of hydrofluoric acid on glass (silicon dioxide), the acid composition, heating stability, and immersion time are selected according to the steel type. The design is reasonable, and the removal of glass powder adhering to the "pressure residue" surface is continuous, stable, efficient, safe, reliable, environmentally friendly, practical and efficient.

[0055] 2. The orderly ratio of hydrofluoric acid and nitric acid effectively separates and dissolves the glass powder adhering to the surface of the "pressure residue," a first in the industry;

[0056] 3. By heating with steam, the difference in thermal expansion coefficients between metal and glass powder is utilized to accelerate the crushing and separation of glass powder and improve corrosion and dissolution efficiency, thereby reducing the soaking time in acid solution and lowering energy consumption;

[0057] 4. By adopting a chemical removal method, the labor intensity of manually removing glass dust is reduced from the source, and the safety and environmental hazards of glass dust splashing are reduced.

[0058] 5. Easy to operate, effectively improves occupational health risks, has a good glass powder removal effect, and provides quality assurance for remelting.

[0059] 6. Fully utilize the corrosive properties of hydrofluoric acid on glass (silicon dioxide), and leverage the company's existing pickling production line equipment. This approach requires no additional investment in equipment and facilities, resulting in low cost, minimal expenses, convenient operation, and easy on-site implementation.

[0060] 7. Removing the "residue" of glass powder can meet the requirements of electric furnace smelting of stainless steel and alloy steel, avoid abnormalities in the production of harmful elements caused by the adhering glass powder, and make it a high-quality raw material for electric furnace smelting. This can increase the selling price of recycled steel and create certain economic benefits.

[0061] 8. It has strong versatility and is of certain reference and application value for the removal of glass powder adhering to the surface of the "pressure residue" generated in the high-temperature extrusion pipe production of seamless steel pipes in the industry.

[0062] This invention is particularly suitable for the green and environmentally friendly disposal of residues after high-temperature hot extrusion of seamless steel pipes. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the "compression residue" structure in extrusion tube manufacturing.

[0064] Figure 2 This is a process flow diagram for removing glass powder adhering to the surface of the "residue" by chemical methods. Detailed Implementation

[0065] A steel pipe plant of a steel company in Shanghai implemented a method for removing glass powder from the alloy surface of tail material after high-temperature extrusion, which is an improvement on the traditional method for removing glass powder adhering to the surface of "extrusion residue" generated during the high-temperature extrusion of seamless steel pipes. Based on the principle of SiO2(s) + 4HF(aq) = SiF4(g)↑ + 2H2O(l), the method consists of six processes: "extrusion residue" collection → work preparation → acid pickling and soaking → cleaning → surface cleaning → inspection and warehousing.

[0066] 1) Collection of “Residual Material”: According to the technical requirements on the production process card, collect the “residual material” after the hot saw has been cut online and cooled to room temperature according to the production batch, and place it in the warehouse next to the machine according to the steel type and specifications.

[0067] 2) Homework preparation:

[0068] (1) Preparation of “Residual” materials: Take “residual” materials of the corresponding steel type and specifications from the machine side warehouse according to the production plan → Clean the glass powder on the surface of “residual” materials one by one with a wooden hammer → Remove the loosened glass powder from the surface of “residual” materials → Transport the “residual” materials after preliminary cleaning to the pickling area in batches.

[0069] (2) Determine pickling (soaking) parameters

[0070] A. Determine the composition (concentration and ratio) of the acid solution: The acid solution is made of hydrofluoric acid and nitric acid in a 1:2 ratio. The ratio of the mixed acid of hydrofluoric acid and nitric acid to water is 1:3. The ratio of hydrofluoric acid to nitric acid can be adjusted appropriately according to the steel grade, with 1: (2.0~2.5) being appropriate.

[0071] B. Determine the acid solution temperature: The acid solution is composed of hydrofluoric acid, nitric acid, and water. The (steam) heating temperature is adjusted according to the steel grade, preferably between 50 and 70°C. The higher the alloy content, the higher the temperature, and the lower the alloy content, the slightly lower the temperature. The ambient temperature should also be taken into full consideration, and the immersion temperature should be at least 40°C higher than the ambient temperature of the day.

[0072] 3) Acid washing and soaking:

[0073] (1) Determine the soaking time: Depending on the type and specifications of steel, the soaking time should be 2.0 to 4.0 hours.

[0074] (2) Soaking preparation: The mixed acid solution in the pickling tank is preheated to the set temperature, and steam heating is maintained during the soaking process to ensure that the temperature of the mixed acid solution meets the set temperature.

[0075] (3) Immersion method: Full volume immersion method is adopted (the temperature of the mixed acid solution has reached the set temperature), that is, the "pressure residue" is connected by polymer slings (or ropes) according to the steel type and specifications → the whole is lifted and immersed in the pickling tank by a crane (crane), and the two ends of the slings (ropes) are fixed on the railings on both sides of the pickling tank → the "pressure residue" is placed flat at the bottom of the pickling tank, and the top surface should be at least 100mm away from the acid solution surface.

[0076] (4) Number of pickling soaks: Based on the length of the pickling tank and the length of the polymer sling (rope), the number of "residual" slings connected by a single sling (rope) should not exceed 30.

[0077] 4) Cleaning: Use a crane to vertically lift the "residue" connected by polymer slings (or ropes) as a whole → The crane hovers for no less than 10 minutes (to drain the acid) → The crane lifts the "residue" as a whole to the cleaning platform → Clean with factory-made high-pressure water jet for no less than 10 minutes, using concentrated spraying of the inner hole, followed by spraying the outside, and then back and forth spraying and sweeping for no less than 3 times → After cleaning, the "residue" is lifted by the crane to the cleaning platform and left to stand for no less than 20 minutes to drain the water.

[0078] 5) Surface cleaning: Manually remove the polymer slings (or ropes) → Place each "residue" on the cleaning table with the large-diameter cylinder facing down → While placing the "residue", check the removal status of the glass powder adhering to its surface → Use a wooden hammer to knock away the residual glass powder that has not been corroded and separated and is still attached to the surface of the "residue".

[0079] 6) Inspection and warehousing: Inspect the surface of the cleaned "residue" to ensure that there is no glass powder residue → Place the "residue" that is confirmed to be free of glass powder residue into a barn bag (separate bags according to steel type) → Hoist the cleaned "residue" into the machine-side warehouse → Register the information, enter it into the account, and hang the nameplate.

[0080] According to the above process (step) model, the glass powder adhering to the surface of the alloy "extrusion residue" generated in the high-temperature extrusion pipe production of seamless steel pipe can be removed and processed to become qualified return steel material, which can meet the process technology requirements of "extrusion residue" smelting and processing, and can be used as high-quality raw material for electric furnace smelting production of related stainless steel and alloy steel.

[0081] A method for removing glass powder from the surface of alloy residue after high-temperature extrusion is an improvement on traditional methods for removing glass powder adhering to the "extrusion residue" surface produced during the high-temperature extrusion of seamless steel pipes. It fully utilizes the corrosive properties of hydrofluoric acid on glass (silicon dioxide), and the acid composition, heating stability, and immersion time are selected based on the steel grade. The method is rationally designed to ensure continuous, stable, and highly efficient removal of glass powder adhering to the "extrusion residue" surface, while being safe, reliable, environmentally friendly, practical, and highly efficient. The method employs an ordered ratio of hydrofluoric acid and nitric acid to effectively separate and dissolve the glass powder adhering to the "extrusion residue" surface, a first in the industry. Steam heating utilizes the difference in thermal expansion coefficients between metal and glass powder to accelerate the crushing, separation, and corrosion dissolution of the glass powder, reducing immersion time and energy consumption in the acid solution. The chemical removal method reduces the labor intensity of manual glass powder removal from the source, minimizing the safety and environmental hazards of glass powder splashing. The method is convenient to operate, effectively reducing labor intensity, and provides excellent glass powder removal, ensuring quality for remelting. It also effectively mitigates occupational health risks and provides excellent glass powder removal, ensuring quality for remelting. Utilizing existing pickling production line equipment, this method requires no additional investment in equipment and facilities, resulting in low cost, minimal expenses, and ease of on-site implementation. Removing glass powder residue from the surface meets the requirements of electric arc furnace smelting for stainless steel and alloy steel, preventing abnormalities in harmful elements during smelting production caused by adhering glass powder. This provides high-quality raw materials for electric arc furnace smelting, increases the selling price of recycled steel, and can generate economic benefits exceeding 300,000 yuan annually. It is highly versatile and has significant reference and application value for the removal of glass powder adhering to the surface of residue generated during the high-temperature extrusion of seamless steel pipes in the industry.

[0082] Example 1

[0083] Taking 60 pieces of alloy "residue" generated during the high-chromium, high-molybdenum, copper-containing nickel-based ultra-low carbon austenitic alloy UNS N08028 (also known as Alloy 28) high-temperature extrusion tube production with a specification of φ250*21mm as an example, the process for removing glass powder is as follows: The operation takes place in spring (average temperature 15~20℃).

[0084] 1) Collection of “Residual Steel”: According to the technical requirements on the production process card, collect the “residual steel” of UNS N08028 with specifications of φ250*21mm after the hot saw has been cut online and cooled to room temperature, according to the production batch, and place it in the warehouse next to the machine according to the steel type and specifications.

[0085] 2) Homework preparation:

[0086] (1) Preparation of “Excess”: According to the production plan, take 60 pieces of “excess” with extrusion specification φ250*21mm and grade (steel type) UNS N08028 from the machine side warehouse. → Clean the glass powder on the surface of the “excess” one by one with a wooden hammer. → Remove the loosened glass powder from the surface of the “excess”. → Transport the 60 pieces of “excess” after preliminary cleaning to the pickling area in two batches.

[0087] (2) Determine pickling (soaking) parameters

[0088] A. Determine the composition (concentration, ratio) of the acid solution: The acid solution for UNS N08028 steel grade is made of hydrofluoric acid and nitric acid in a ratio of 1:2.4. The ratio of the mixed acid of hydrofluoric acid and nitric acid to water is preferably 1:3.

[0089] B. Determine the acid solution temperature: The acid solution is composed of hydrofluoric acid, nitric acid and water. The (steam) heating temperature is adjusted according to the UNS N08028 steel grade, preferably 60~75℃, especially 65~70℃, and this temperature is not less than 40℃ higher than the ambient temperature of the day.

[0090] 3) Acid washing and soaking:

[0091] (1) Determine the soaking time: Based on the specifications φ250*21mm and steel grade UNS N08028, the soaking time should be 2.5~4.0 hours, especially 3.0~3.5 hours.

[0092] (2) Immersion method: The full volume immersion method is adopted, that is, the "pressure residue" is based on the specification φ250*21mm, steel grade UNSN08028, 30 pieces of "pressure residue" are connected by polymer slings, and 60 pieces of "pressure residue" are connected by 2 polymer slings respectively. → The whole piece is lifted and immersed in the pickling tank by a crane (overhead crane), and the two ends of the slings are fixed on the railings on both sides of the pickling tank. → The "pressure residue" is placed flat at the bottom of the pickling tank, and the top surface is at least 110mm away from the acid liquid surface.

[0093] 4) Cleaning: Using a crane, 60 pieces of "pressure residue" connected by two polymer slings are vertically lifted (lifted) → The crane is suspended for 12 minutes (to drain the acid) → The crane lifts the "pressure residue" as a whole to the cleaning platform → High-pressure water jet cleaning is carried out using the factory's high-pressure water jet. The high-pressure water jet spraying time is not less than 12 minutes. The internal holes are sprayed in a concentrated manner, followed by the external holes, and then back and forth is sprayed and swept 4 times → After cleaning, the "pressure residue" is lifted by the crane to the cleaning platform and left to stand for 25 minutes to drain the water.

[0094] 5) Surface cleaning: Manually remove the polymer slings → Place 60 “residual pressure” pieces one by one on the cleaning table with the large diameter cylinder facing down → While placing the “residual pressure” pieces, check the removal status of the glass powder adhering to their surface → Use a wooden hammer to knock away the residual glass powder that has not been corroded and separated and is still attached to the surface of the “residual pressure” pieces.

[0095] 6) Inspection and warehousing: Inspect the surface of the cleaned "residue" to ensure that there is no glass powder residue → Place the "residue" of specification φ250*21mm and steel grade UNS N08028 that has been confirmed to be free of glass powder residue into a barn bag one by one → Hoist the cleaned "residue" into the machine-side warehouse → Register the information, enter it into the account, and hang the nameplate.

[0096] Example 2

[0097] Taking 120 pieces of alloy "residue" generated during the high-temperature extrusion tube production of GB2205 (022Cr23Ni5Mo3N), a duplex corrosion-resistant stainless steel containing chromium, nickel, molybdenum, etc., with an extrusion specification of φ76*7mm, as an example, the process for removing glass powder is as follows: (The text abruptly ends here, so the translation stops as well.)

[0098] 1) Collection of “Residual Steel”: According to the technical requirements on the production process card, collect the “residual steel” of GB2205 with a specification of φ76*7mm after the hot saw has been cut online and cooled to room temperature, according to the production batch, and place it in the warehouse next to the machine according to the steel type and specification.

[0099] 2) Homework preparation:

[0100] (1) Preparation of “Excess”: In accordance with the production plan, 120 pieces of “excess” with extrusion specification φ76*7mm and grade (steel type) GB2205 were taken from the machine side warehouse. → The glass powder on the surface of the “excess” was cleaned one by one with a wooden hammer. → The loosened glass powder was removed from the surface of the “excess”. → The 120 pieces of “excess” after preliminary cleaning were transported to the pickling area in 4 batches.

[0101] (2) Determine pickling (soaking) parameters

[0102] A. Determine the composition (concentration, ratio) of the acid solution: The acid solution for GB2205 steel grade is made of hydrofluoric acid and nitric acid in a ratio of 1:2.0. The ratio of the mixed acid of hydrofluoric acid and nitric acid to water is preferably 1:3.

[0103] B. Determine the acid solution temperature: The acid solution is composed of hydrofluoric acid, nitric acid and water. The (steam) heating temperature is adjusted according to the UNS GB2205 steel grade, preferably 50~70℃, especially 60~70℃, and this temperature is not less than 40℃ higher than the ambient temperature of the day.

[0104] 3) Acid washing and soaking:

[0105] (1) Determine the soaking time: According to the specifications φ76*7mm and steel grade GB2205, the soaking time should be 2.0~3.0 hours, especially 2.0~2.5 hours.

[0106] (2) Immersion method: The full volume immersion method is adopted, that is, the "pressure residue" is based on the specification φ76*7mm, steel grade UNSGB2205, 30 pieces of "pressure residue" are connected by polymer slings, and 120 pieces of "pressure residue" are connected by 4 polymer slings respectively. → The whole piece is lifted and immersed in the pickling tank by a crane (overhead crane), and the two ends of the slings are fixed on the railings on both sides of the pickling tank. → The "pressure residue" is placed flat at the bottom of the pickling tank, and the top surface is at least 150mm away from the acid liquid surface.

[0107] 4) Cleaning: Using a crane, 120 pieces of "pressure residue" connected by 4 polymer slings are vertically lifted (lifted) → The crane is suspended for 10 minutes (to drain the acid) → The crane lifts the "pressure residue" as a whole to the cleaning platform → High-pressure water jet cleaning is carried out using the factory's high-pressure water jet. The high-pressure water jet spraying time is no less than 10 minutes. The internal holes are sprayed in a concentrated manner, followed by the external holes, and then back and forth is sprayed and swept 4 times → After cleaning, the "pressure residue" is lifted by the crane to the cleaning platform and left to stand for 20 minutes to drain the water.

[0108] 5) Surface cleaning: Manually remove the polymer slings → Place 120 “residual pressure” pieces one by one on the cleaning table with the large diameter cylinder facing down → While placing the “residual pressure” pieces, check the removal status of the glass powder adhering to their surface → Use a wooden hammer to knock away the residual glass powder that has not been corroded and separated and is still attached to the surface of the “residual pressure” pieces.

[0109] 6) Inspection and warehousing: Inspect the surface of the cleaned "residue" to ensure that there is no glass powder residue → Place the "residue" of specification φ76*7mm and steel grade GB2205 that has been confirmed to be free of glass powder residue into a barn bag one by one → Hoist the cleaned "residue" into the machine-side warehouse → Register the information, enter it into the account, and hang the nameplate.

[0110] Example 3

[0111] Taking 90 pieces of alloy "residue" generated during the high-temperature extrusion tube production of S32750 (25Cr-7Ni-3.7Mo-0.3N) super duplex stainless steel with an extrusion specification of φ135*16mm as an example, the process for removing glass powder during winter (average temperature 0~10℃) is as follows:

[0112] 1) Collection of “Residual Steel”: According to the technical requirements on the production process card, collect the “residual steel” of S32750 steel with a specification of φ135*16mm after online cutting by hot saw and cooling to room temperature, according to the production batch, and place it in the warehouse next to the machine according to the steel type and specification.

[0113] 2) Homework preparation:

[0114] (1) Preparation of “Excess”: According to the production plan, take 90 pieces of “excess” with extrusion specification φ135*16mm and grade (steel type) S32750 from the machine side warehouse. → Clean the glass powder on the surface of the “excess” one by one with a wooden hammer. → Remove the loosened glass powder from the surface of the “excess”. → Transport the 90 pieces of “excess” after preliminary cleaning to the pickling area in 3 batches.

[0115] (2) Determine pickling (soaking) parameters

[0116] A. Determine the composition (concentration, ratio) of the acid solution: The acid solution for S32750 steel is made of hydrofluoric acid and nitric acid in a ratio of 1:2.2. The ratio of the mixed acid of hydrofluoric acid and nitric acid to water is preferably 1:3.

[0117] B. Determine the acid solution temperature: The acid solution is composed of hydrofluoric acid, nitric acid and water. The (steam) heating temperature is adjusted according to the UNS N08028 steel grade, preferably 60~75℃, especially 65~70℃, and this temperature is not less than 40℃ higher than the ambient temperature of the day.

[0118] 3) Acid washing and soaking:

[0119] (1) Determine the soaking time: Based on the specifications φ136*16mm and steel grade S32750, the soaking time should be 2.5~4.0 hours, especially 3.0~3.5 hours.

[0120] (2) Immersion method: The full volume immersion method is adopted, that is, the "pressure residue" is based on the specifications φ135*16mm, steel grade S32750, 90 pieces of "pressure residue" are connected by polymer slings, and the 90 pieces of "pressure residue" are connected by 3 polymer slings respectively. The whole piece is lifted and immersed in the pickling tank by a crane (overhead crane), and the two ends of the slings are fixed on the railings on both sides of the pickling tank. The "pressure residue" sinks to the bottom and is placed flat at the bottom of the pickling tank, with the top surface at least 120mm away from the surface of the acid liquid.

[0121] 4) Cleaning: Using a crane, 90 pieces of "pressure residue" connected by 3 polymer slings are vertically lifted (lifted) → The crane is suspended for 15 minutes (to drain the acid) → The crane lifts the "pressure residue" as a whole to the cleaning platform → High-pressure water jet cleaning is carried out using the factory's high-pressure water jet spray for no less than 15 minutes. The spray is concentrated on the inner hole, then the outside is sprayed, and then back and forth is sprayed and swept 4 times → After cleaning, the "pressure residue" is lifted by the crane to the cleaning platform and left to stand for 25 minutes to drain the water.

[0122] 5) Surface cleaning: Manually remove the polymer slings → Place each of the 90 “residual pressure” pieces on the cleaning table with the large-diameter cylinder facing down → While placing the “residual pressure” pieces, check the removal status of the glass powder adhering to their surface → Use a wooden hammer to knock away the residual glass powder that has not been corroded and separated and is still attached to the surface of the “residual pressure” pieces.

[0123] 6) Inspection and warehousing: Inspect the surface of the cleaned "residue" to ensure that there is no glass powder residue → Place the "residue" of specification φ135*16mm and steel grade S32750 that has been confirmed to be free of glass powder residue into a barn bag one by one → Hoist the cleaned "residue" into the machine-side warehouse → Register the information, enter it into the account, and hang the nameplate.

Claims

1. A method for removing glass powder from the surface of alloy residue after high-temperature extrusion, characterized in that: The process includes: "residual" collection → work preparation → pickling and soaking → cleaning → surface cleaning. 1) Collection of "Residual Material": According to the technical requirements on the production process card, collect the "residual material" after the hot saw has been cut online and cooled to room temperature according to the production batch, and place it in a centralized manner according to steel type and specifications; 2) Homework preparation: (1) Preparation of "Residue": Clean the glass powder on the surface of "Residue", remove the glass powder from the surface of "Residue", and transport it to the pickling area in batches; (2) Determine pickling parameters The acid solution is prepared by mixing hydrofluoric acid solution and nitric acid solution in a mass ratio of 1:2-2.5, and the ratio of the mixed acid of hydrofluoric acid and nitric acid to water is 1:3; in the hydrofluoric acid solution, the volume ratio of hydrofluoric acid to water is 1:2-4; in the nitric acid solution, the volume ratio of nitric acid to water is 1:2-4. Determine the acid solution temperature: the acid solution temperature should be 50~70℃; 3) Acid washing and soaking: The mixed acid solution in the pickling tank is preheated to the set temperature and kept heated during the soaking process to ensure that the temperature of the mixed acid solution meets the set temperature. The full-volume immersion method is adopted, and the top surface of the "pressure residue" is at least 100mm away from the surface of the acid solution. Soaking time is 2.0~4.0 hours; 4) Cleaning: After lifting the "residual" acid using a lifting device, the acid solution is fully drained, then sprayed for cleaning, and the water is drained. 5) Surface cleaning: Place each "pressure residue" on the cleaning table with the large-diameter cylinder facing down, check the glass powder adhesion on its surface, and if there is adhesion, remove it by tapping.

2. The method for removing glass powder from the surface of alloy residue after high-temperature extrusion according to claim 1, characterized in that: In step 2), during the preparation of the operation, the residual pressure is removed manually with a hand hammer.

3. The method for removing glass powder from the surface of alloy residue after high-temperature extrusion according to claim 1, characterized in that: Step 3) During pickling and soaking, the number of "residues" connected by a single suspension rope shall not exceed 30.

4. The method for removing glass powder from the surface of alloy residue after high-temperature extrusion according to claim 1, characterized in that: In step 4), the lifting device is a crane; the spray cleaning involves first spraying the inner hole, then spraying the outside, and then spraying back and forth for no less than 3 times.

5. The method for removing glass powder from the surface of alloy residue after high-temperature extrusion according to claim 1, characterized in that: Step 5) The knocking removal is done manually with a hammer.

6. A method for removing glass powder from the surface of alloy residue after high-temperature extrusion, as described in claim 2 or 5, characterized in that: Step 2) The manual hammer cleaning should be done at a rate of 30-60 times per minute; Step 5) The knocking removal should be done manually with a hammer at a rate of 30-60 times per minute.

7. A method for removing glass powder from the surface of alloy residue after high-temperature extrusion, as described in claim 6, characterized in that: In step 2), a wooden hammer is used for manual hammering; in step 5), a wooden hammer is used for manual hammering.

8. The method for removing glass powder from the surface of alloy residue after high-temperature extrusion according to claim 1, characterized in that: After step 5), inspect the cleaned "residue" surface to ensure that there is no glass powder residue before inspecting and storing it.

9. A method for removing glass powder from the surface of alloy residue after high-temperature extrusion, as described in claim 1, characterized in that: In step (2), the acid immersion temperature is 40°C or higher than the air temperature.

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