A method for zinc plating in a zinc pot of an aluminum-zinc plating production line

Abstract

The present application provides a method for zincing in a zinc pot on an galvanized production line, relating to the cold rolling field of the metallurgical industry. The composition of the alloy ingot used for zincing differs from that of conventional alloy ingots. The first batch of zinc-aluminum alloy ingots added contains 10% aluminum and 90% zinc. The melting point of the zinc-aluminum alloy ingot is 443°C, only 23°C higher than that of pure zinc ingots. Due to the relatively low melting point, when zinc is poured into the throat of an induction heater, the temperature difference between the throat and the zinc liquid is small, which prevents the poured zinc liquid from instantly solidifying and causing the induction heater to fail to melt. Based on the size of the zinc pot, alloy ingots of different compositions are used and added in four batches, with the first three batches containing the same alloy ingot composition. The present invention uses a new zinc-aluminum alloy ingot for zincing in the galvanized zinc pot. The aluminum content of the alloy ingot ensures that the melting point of the alloy ingot is low and that the final zinc liquid composition meets the standard, thereby reducing the risk and cost of zinc pot production, improving efficiency, and shortening the construction period.

Description

Technical Field

[0001] The present application relates to the field of cold rolling technology in the metallurgical industry, and in particular to a method for zinc plating in a zinc pot of an aluminum-zinc plating production line. Background Art

[0002] Compared to conventional galvanized products, galvanized products offer a superior surface gloss and superior atmospheric corrosion resistance, 3 to 6 times greater than that of ordinary galvanized sheet. They also offer high-temperature resistance, with no discoloration at temperatures up to 300°C. They are widely used in industries such as construction, home appliances, and the automotive industry. Furthermore, galvanized products offer low production costs. The galvanized coating is composed of 55% aluminum, 43.5% zinc, and 1.5% silicon, while the galvanized coating is 99% pure zinc. The price of aluminum is generally 3,500 yuan per ton lower than zinc, saving nearly 35% in alloy ingots alone. Furthermore, galvanized products consume less alloy ingots, and a typical 150g / m² zinc coating offers corrosion resistance comparable to the 275g / m² zinc coating of conventional galvanized products. However, galvanized products are more challenging to produce. Taking zinc pot zinc plating as an example, there are two traditional zinc plating methods. The first method is to directly stack alloy ingots of 55% Al, 43.5% Zn and 1.5% Si. However, the melting point of the alloy ingot is around 600°C. When the induction heater starts to melt at the critical link, there is a large temperature difference between the throat temperature of the preheated burner and the injected zinc liquid. This will cause the zinc liquid to solidify instantly, causing the induction heater to fail to melt, resulting in the scrapping of the induction heater and incurring expensive costs.

[0003] The second option uses pure zinc ingots and pure aluminum ingots to be added in batches for zinc plating. Since pure zinc has a relatively low melting point of 420°C, pure zinc ingots are used in the initial zinc plating process. After the induction heater is successfully melted, pure aluminum ingots are added to adjust the composition ratio. However, based on the common zinc pot size calculations in the industry (the induction heater is usually located in the lower middle part of the zinc pot), even if the induction heater is melted and all the pure aluminum ingots are added to the full liquid level, the aluminum content of the final zinc liquid will be lower than the process requirement of 55%. The zinc liquid needs to be pumped out and the pure aluminum ingots added again. This method is time-consuming and wastes a lot of zinc ingots. In addition, this method involves zinc extraction, which is costly and dangerous. However, this method has a low risk of failure and is generally adopted by the industry.

[0004] In order to improve the efficiency of zinc plating, reduce costs and risks, a new aluminum zinc plating melting method is needed, which can ensure that the temperature difference between the inside of the induction heater melting throat and the zinc liquid is small, and the chemical composition of the zinc liquid meets the final process requirements. Summary of the Invention

[0005] The object of the present invention is to provide a method for zinc plating in a zinc pot of an galvanizing production line, which has the beneficial effects of reducing the risk and cost of zinc plating in the zinc pot, improving efficiency and shortening construction period, so as to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for zinc plating in a zinc pot of an galvanizing production line. The composition of the alloy ingots used for zinc plating is different from that of conventional alloy ingots. The first batch of zinc-aluminum alloy ingots contains 10% aluminum and 90% zinc. The melting point of the zinc-aluminum alloy ingot is 443°C, which is only 23°C higher than that of pure zinc ingots. Due to the relatively low melting point, when zinc is poured into the throat of an induction heater, the temperature difference between the throat and the zinc liquid is small, which prevents the poured zinc liquid from solidifying instantly and causing the induction heater to fail to melt.

[0008] As a further solution of the present invention, alloy ingots of different compositions are used according to the size of the zinc pot and are placed in four batches. The first three batches contain alloy ingots of the same composition; the fourth batch contains alloy ingots of different compositions.

[0009] As a further solution of the present invention: the zinc liquid composition used in the galvanizing process is: aluminum content 55%±3%, zinc content 43.5%±3% and silicon content 1.5%±0.5%.

[0010] As a further solution of the present invention, by designing different components, the final zinc liquid composition meets production requirements, and there is no need for component transition, thus saving production costs.

[0011] As a further solution of the present invention: after the first batch of alloy ingots are melted, the liquid level is 3 cm away from the lower edge of the throat. This distance can not only prevent the zinc liquid level from fluctuating and causing the zinc liquid to accidentally pour into the throat from the lower edge of the throat and solidify, causing the induction heater to fail to melt; but also ensure that after the second batch of alloy ingots, 2 to 3 pieces, are added, they can be quickly connected with the zinc liquid poured into the throat, ensuring that the zinc liquid in the throat does not solidify and the induction heater will not be damaged.

[0012] As a further solution of the present invention: after the third batch of alloy ingots are added, the zinc liquid level is 10 cm higher than the lower edge of the throat, and the induction heater has been running at low power for 24 hours, the high power mode can be turned on.

[0013] As a further solution of the present invention: the pure aluminum ingot is allowed to be added only after the induction heater is turned on in high power mode.

[0014] As a further solution of the present invention: the induction heater is turned on in high power mode, and pure aluminum ingots and aluminum silicon ingots are added to the zinc liquid to adjust the composition. The addition of ingots is stopped when the distance from the zinc pot liquid level is 10 to 15 cm. At this time, the composition of the aluminum-zinc liquid in the pot is calculated to be 55% Al content, 43.5% Zn content and 1.5% Si content, which meets production requirements.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention uses a novel zinc-aluminum alloy ingot for aluminum-zinc plating and zinc pot zinc plating. The aluminum content of the alloy ingot can ensure that the melting point of the alloy ingot is low and the final zinc liquid composition meets the standard, thereby reducing the risk and cost of zinc pot production and zinc plating, and improving efficiency and shortening the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] To more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0018] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings. In the following description, the same reference numerals represent the same parts.

[0019] Figure 1 A schematic diagram of a zinc pot zinc plating method for an aluminum zinc plating production line provided in an embodiment of the present application.

[0020] Markings in the figure:

[0021] 1. Throat; 2. Induction heater. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0023] Please refer to the attached Figure 1The embodiment of the present application provides a method for zincing in a zinc pot of an galvanizing production line. The composition of the alloy ingot used for zincing is different from that of the previous alloy ingots. The first batch of zinc-aluminum alloy ingots added contains 10% aluminum and 90% zinc (marked A10). The melting point of the zinc-aluminum alloy ingot is 443°C, which is only slightly higher than that of pure zinc ingot (pure zinc melting point is 420°C) by 23°C. Due to the relatively low melting point, when zinc is poured into the throat 1 of the induction heater 2, the temperature difference between the throat 1 and the zinc liquid is not large, which will cause the poured zinc liquid to solidify instantly and the induction heater 2 to fail to melt. Furthermore, the zinc liquid used in the galvanizing process has the following composition: aluminum content 55%±3%, zinc content 43.5%±3% and silicon content 1.5%±0.5%. The present invention uses a novel zinc-aluminum alloy ingot for aluminum-zinc plating and zinc pot zinc plating. The aluminum content of the alloy ingot can ensure that the melting point of the alloy ingot is low and the final zinc liquid composition meets the standard, thereby reducing the risk and cost of zinc pot production and zinc plating, and improving efficiency and shortening the construction period.

[0024] In a preferred embodiment of the present invention, alloy ingots of different compositions are used according to the size of the zinc pot and are placed in four batches. The first three batches contain alloy ingots of the same composition; the fourth batch contains alloy ingots of different compositions. Furthermore, through the design of different compositions, the final zinc liquid composition meets production requirements, and there is no need for composition transition, thereby saving production costs.

[0025] In a preferred embodiment of the present invention, after the first batch of alloy ingots are melted, the liquid level is 3 cm away from the lower edge of the throat 1. This distance can not only prevent the zinc liquid from fluctuating and causing the zinc liquid to accidentally pour into the throat 1 from the lower edge of the throat 1 and solidify, causing the induction heater 2 to fail to melt; it can also ensure that after 2 to 3 pieces of the second batch of alloy ingots are added, they can be quickly connected with the zinc liquid poured into the throat 1, ensuring that the zinc liquid in the throat 1 does not solidify and the induction heater 2 is not damaged; further, after the third batch of alloy ingots are added, the zinc liquid level is higher than the lower edge of the throat 1 by 10 cm, and the induction heater 2 has been running at low power for 24 hours, the high power mode can be turned on; further, pure aluminum ingots are allowed to be added only after the induction heater 2 is turned on in high power mode.

[0026] In a preferred embodiment of the present invention, the induction heater 2 is turned on in high power mode, and pure aluminum ingots and aluminum silicon ingots are added to the zinc liquid to adjust the composition. The addition of ingots is stopped when the zinc pot liquid level is 10 to 15 cm. At this time, the composition of the aluminum-zinc liquid in the pot is calculated to be 55% Al content, 43.5% Zn content and 1.5% Si content, which meets production requirements.

[0027] The present invention provides a method for zinc plating in a zinc pot of an galvanizing production line, the method comprising the following steps:

[0028] Step 1: Calculate the weight of the first batch of zinc-aluminum alloy ingots with an aluminum content of 10%, according to Figure 1As shown, considering that the liquid level is required to be 3 cm below the bottom edge of the throat 1 after the first zincization, the required volume V1 is 12.46 m 3 ; Based on the density of A10 alloy ingot 6.135g / cm 3 It is calculated that the total weight of the first batch of A10 alloy ingots laid is about 76.44 tons.

[0029] Step 2: After the first batch of A10 alloy ingots are laid, the natural gas pipeline is set up as required and ignition and heating are started. The zinc pot must be baked as a whole according to the heating curve (thermocouples are laid in the zinc pot in advance). After the baking is completed, the natural gas is kept burning to start melting the A10 alloy ingots.

[0030] The third step is to heat the molten zinc liquid to 460-480℃ after the A10 alloy ingot is completely melted and the liquid level should reach about 3cm below the throat 1.

[0031] The fourth step is to turn on the induction heater 2 of the throat 1 and put it in a low-power state after the zinc liquid temperature reaches 480°C. Then, use the nitrogen pipe to blow the molten zinc liquid into the throat 1 immediately. At this time, the induction heater 2 has started working, but has not yet connected to the zinc liquid in the pot. It is necessary to quickly add 2 to 3 A10 alloy ingots into the zinc liquid to make the zinc liquid in the induction heater 2 contact with the zinc liquid in the pot (the faster the better, while ensuring that the temperature drop does not exceed 10°C). Then continue to add A10 alloy ingots. When the zinc liquid level submerges the position about 10 cm above the lower edge of the throat, the liquid in the pot and the liquid in the throat are connected. At this time, the induction heater 2 is still controlled in a low-power state. The induction heater 2 starts to melt successfully. At this time, the zinc pot contains about 90 tons of A10 alloy ingots.

[0032] Step 5: After 24 hours of induction heater 2 melting, it can be turned on normally at high power mode, and pure aluminum ingots and aluminum silicon ingots are added to adjust the composition. According to calculations, when the zinc liquid level reaches 10cm from the upper edge of the zinc pot, the zinc liquid composition meets production requirements and the zinc pot zincing work is completed.

[0033] The present invention uses a novel zinc-aluminum alloy ingot for aluminum-zinc plating and zinc pot zinc plating. The aluminum content of the alloy ingot can ensure that the melting point of the alloy ingot is low and the final zinc liquid composition meets the standard, thereby reducing the risk and cost of zinc pot production and zinc plating, and improving efficiency and shortening the construction period.

[0034] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0035] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more features.

[0036] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for technical personnel in this field, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on this application.

Claims

1. A method for zincating in a zinc pot of an aluminum zinc plating production line, characterized in that: The composition of the alloy ingots used for zinc plating is different from that of previous alloy ingots. The first batch of zinc-aluminum alloy ingots contains 10% aluminum and 90% zinc. The melting point of the zinc-aluminum alloy ingot is 443°C, which is only 23°C higher than that of pure zinc ingot. Due to its relatively low melting point, when zinc is poured into the throat of the induction heater, the temperature difference between the throat and the zinc liquid is small, which will not cause the poured zinc liquid to solidify instantly and fail to melt the induction heater. The zinc solution used in the galvanizing process has the following composition: aluminum content 55% ± 3%, zinc content 43.5% ± 3% and silicon content 1.5% ± 0.5%; According to the size of the zinc pot, alloy ingots of different compositions are used and placed in four batches. The first three batches contain alloy ingots of the same composition; the fourth batch contains alloy ingots of different compositions. After the first batch of alloy ingots melted, the liquid level was 3 cm away from the bottom edge of the throat. This distance can prevent the zinc liquid from fluctuating and causing the zinc liquid to accidentally pour into the throat from the bottom edge of the throat and solidify, causing the induction heater to fail to melt; it can also ensure that after the second batch of alloy ingots are added, 2 to 3 pieces can be quickly connected with the zinc liquid poured into the throat, ensuring that the zinc liquid in the throat does not solidify and the induction heater will not be damaged.

2. The method for zincification in a zinc pot of an galvanizing production line according to claim 1, wherein: After the third batch of alloy ingots is added, the high power mode can be turned on only after the zinc liquid level is 10 cm higher than the lower edge of the throat and the induction heater has been running at low power for 24 hours.

3. The method for zincification in a zinc pot of an galvanizing production line according to claim 2, wherein: Pure aluminum ingots are allowed to be added only after the induction heater is turned on in high power mode.

4. The method for zincification in a zinc pot of an galvanizing production line according to claim 3, wherein: The induction heater is turned on in high power mode, and pure aluminum ingots and aluminum silicon ingots are added to the zinc liquid to adjust the composition. The addition of ingots is stopped when the distance from the zinc pot liquid level is 10 to 15 cm. At this time, the composition of the aluminum-zinc liquid in the pot is calculated to be 55% Al, 43.5% Zn and 1.5% Si, which meets the production requirements.

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