Recovery smelting method of zirconium alloy defective materials and application of recovery smelting method

Abstract

The invention belongs to the technical field of zirconium alloy material preparation, and relates to a recovery smelting method and application of zirconium alloy defective materials, the recovery smelting method comprises the following steps: taking nuclear-grade zirconium alloy defective materials as raw materials, adopting the processes of screening the defective materials, preparing electrodes, carrying out electron beam smelting and carrying out vacuum self-consuming electric arc smelting, and controlling different smelting process parameters to obtain the zirconium alloy defective materials. The problem that high-content Sn, Fe and Cr elements in the zirconium alloy are converted into low-content Sn, Fe and Cr elements is perfectly solved, the recovery range and flexibility of the zirconium alloy defective materials are improved, and the method has the advantages of being low in investment, easy to operate and easy to achieve industrial production. The prepared titanium alloy defective ingot is sampled and analyzed, the chemical components of the zirconium alloy meet the technical condition requirements, and the prepared product is stable in quality and good in economical efficiency and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of zirconium alloy material preparation, and particularly relates to a zirconium alloy residual material recycling and smelting method and application thereof. BACKGROUND

[0002] Since the 21st century, China's nuclear power industry has entered a rapid development stage, and the demand for nuclear-grade zirconium alloys, as key structural materials for nuclear reactor cores, has increased significantly. The localization process of nuclear-grade zirconium alloys is also gradually advancing. Currently, various grades of zirconium alloys have been developed at home and abroad, such as Zr-4 alloy, HANA alloy, E635 alloy, Zirlo alloy, M5 alloy, and domestic N36 alloy, N18 alloy, etc. These zirconium alloys are widely used in key components such as nuclear reactor cladding.

[0003] The nominal chemical composition of the above-mentioned different grades of nuclear-grade zirconium alloys differs significantly, as shown in the following table. In commercial nuclear power zirconium materials, the use of Zirlo, Zr-4, M5, N36, etc. accounts for more than 90%, but these alloys differ significantly in the content of key elements such as Sn, Fe, and Cr. For example, Cr is a major element in Zr-4 and N18 alloys, with a content of about 0.1%, while in Zirlo and N36 alloys, Cr is an impurity element, with a content of less than 0.005%. The Fe element content in N18 and E635 alloys is about 0.35%, while in Zirlo and N36 alloys, it is between 0.1% and 0.3%. The Sn element content in different grades of zirconium alloys also differs significantly.

[0004] Common nuclear-grade zirconium alloy grades and nominal composition Currently, a large amount of residual material is generated during the production and processing of zirconium alloys, but the existing recycling of zirconium alloy residual material has obvious limitations: only the same grade or similar chemical composition of zirconium alloy residual material can be recycled, and high-alloy-element-content zirconium alloy residual material cannot be converted into low-alloy-element-content zirconium alloy, resulting in narrow recycling range and low efficiency. A large amount of zirconium alloy residual material cannot be effectively utilized, not only causing resource waste, but also increasing production cost, which is not conducive to the green and sustainable development of the nuclear-grade zirconium alloy industry. Therefore, it is urgent to develop a residual material treatment method that can convert high-content Sn, Fe, and Cr elements in zirconium alloy to low-content Sn, Fe, and Cr elements, to broaden the recycling range and improve resource utilization.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for recycling and smelting zirconium alloy scrap and its application, so as to solve the problem of transforming high content Sn, Fe, and Cr elements in zirconium alloys into low content Sn, Fe, and Cr elements.

[0007] The objective of this invention is achieved through the following technical solution: On the one hand, the present invention provides a method for recycling and smelting zirconium alloy scrap. Using nuclear-grade zirconium alloy scrap as raw material, the method adopts the process of "screening scrap → preparing electrodes → electron beam melting → vacuum consumable arc melting". By controlling different melting process parameters, partial removal of Sn, Fe and Cr elements is achieved to obtain nuclear-grade zirconium alloy scrap ingots that meet the requirements.

[0008] Specifically, see Figure 1 As shown, the above-mentioned recycling and smelting method specifically includes the following steps: Step 1: Screening and pre-treatment of residual materials: Screening for nuclear-grade zirconium alloy residual materials with high Sn, Fe, and Cr content, and cleaning the surface of the screened nuclear-grade zirconium alloy residual materials; Step 2, Electrode preparation: A consumable electrode is prepared using the nuclear-grade zirconium alloy residue; Step 3, Electron beam melting: The consumable electrode is melted at least twice in an electron beam furnace to obtain an intermediate ingot; Step 4: Vacuum consumable arc melting: The intermediate ingot is melted in a vacuum consumable arc furnace no more than twice to obtain a nuclear-grade zirconium alloy residue ingot with qualified and uniform composition.

[0009] The nuclear-grade zirconium alloy scrap includes chip-like scrap and / or block-like scrap; If the nuclear-grade zirconium alloy scraps are all in the form of shavings, the shavings are first pressed to obtain an electrode block, and then the electrode block is welded to obtain a consumable electrode. If the nuclear-grade zirconium alloy scraps are all in block form, then the block scraps are directly welded to obtain consumable electrodes. If the nuclear-grade zirconium alloy residue is a mixture of chip residue and block residue, then consumable electrodes are prepared separately.

[0010] Specifically, the nuclear-grade zirconium alloy residue contains: Sn content of 0.7wt%~1.4wt%, Fe content of 0.5wt%~1.0wt%, and Cr content of 0.1wt%~0.5wt%.

[0011] The nuclear-grade zirconium alloy scrap ingots obtained using the above-mentioned recycling and smelting method contain: Sn content of 0.1wt%~0.5wt%, Fe content of 0.1wt%~0.5wt%, and Cr content of 0.1wt%~0.5wt%.

[0012] Specifically, in step 3, the process parameters for each electron beam melting are set as follows: vacuum degree before melting ≤ 0.05 Pa, pressure rise rate before melting ≤ 0.1 Pa / min, crystallizer diameter Φ200 mm~Φ300 mm, melting speed 1.2 kg / min~1.5 kg / min, and melting power 120 kW~170 kW.

[0013] Specifically, in step 4, the process parameters for each vacuum self-consuming arc melting are set as follows: vacuum degree before melting ≤ 0.3 Pa, pressure rise rate before melting ≤ 0.1 Pa / min, crystallizer diameter Φ300 mm ~ Φ650 mm, melting speed 16 kg / min ~ 22 kg / min, melting voltage 34 V ~ 36 V, melting current 17 kA ~ 23 kA, and melting stirring magnetic field strength 8 Gs ~ 16 Gs, and it is bidirectional stirring.

[0014] Furthermore, the nuclear-grade zirconium alloy scrap ingot is cooled and removed from the furnace under an inert gas atmosphere. During cooling, the inlet temperature of the cooling water in the crystallizer is 30℃~38℃, and the outlet temperature is 39℃~45℃.

[0015] On the other hand, the present invention also provides the application of the above-described method for recycling and smelting some or all of the zirconium alloy scrap in the recycling of nuclear-grade zirconium alloy scrap.

[0016] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: 1) The technical solution provided by this invention perfectly solves the technical problem of transforming high-content Sn, Fe, and Cr elements in zirconium alloys into low-content Sn, Fe, and Cr elements; at least two electron beam melting processes are added before the existing vacuum arc melting, and the melting speed is reduced (1.2 kg / min~1.5 kg / min) and the vacuum degree requirement is increased (vacuum degree ≤0.05 Pa) during electron beam melting to enhance the purification effect; in addition, since there will be a large difference in composition inside the ingot after electron beam melting, it is necessary to perform no more than two vacuum arc melting processes, and the stirring magnetic field strength is reduced (8 Gs~16 Gs) during vacuum arc melting to make the molten pool rotate in both directions, reduce the cooling intensity during melting, and make the molten pool flattened to promote the full diffusion of alloying elements and increase the cooling intensity, further reducing the macroscopic segregation caused by solidification.

[0017] 2) The technical solution provided by this invention solves the problem that existing nuclear-grade zirconium alloy scraps can only be recycled from zirconium alloys of the same grade or with similar chemical composition, resulting in a low recycling rate. Through at least two electron beam melting processes, the Sn, Fe, and Cr elements in the zirconium alloy are significantly reduced. Simultaneously, after vacuum consumable arc melting, the uniformity of the chemical composition of the zirconium alloy scrap ingot is significantly improved. Furthermore, chemical analysis of samples shows that its chemical composition meets the technical requirements. The finished ingots prepared using this zirconium alloy scrap ingot have stable quality and good economic efficiency.

[0018] 3) The zirconium alloy scrap ingot prepared by this invention has a good chemical composition, which fully meets the requirements of subsequent production, improves the scope and flexibility of zirconium alloy scrap recycling, and has the characteristics of low investment, easy operation, broad application prospects and easy industrial production. Attached Figure Description

[0019] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A flowchart of the method for recycling and smelting zirconium alloy scrap provided by the present invention. Detailed Implementation

[0022] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0023] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] Example 1 This embodiment provides a method for recycling and smelting zirconium alloy scrap, specifically including the following steps: Step 1: Screen the residue and clean the surface of the screened residue: Nuclear-grade zirconium alloy scrap with Sn content of 1.0 wt%, Fe content of 1.0 wt%, and Cr content of 0.5 wt% was screened. The surface of the scrap was cleaned by pre-cleaning, pickling and ultrapure water cleaning to remove impurities and oxide layer, thereby improving the purity and corrosion resistance of the zirconium alloy scrap. Pre-cleaning of shavings involves placing the zirconium material in a clean solvent and stirring it with tools such as ultrasound to remove surface dust and oil. Commonly used solvents include alcohol and deionized water. Pre-cleaning of blocky residues includes surface blasting, shot blasting, etc., to remove the surface oxide layer, followed by acid pickling. Commonly used acid pickling solutions include concentrated nitric acid and hydrofluoric acid. Ultrapure water cleaning can be done by spraying, immersion, or ultrasound to ensure the cleanliness of the zirconium material surface.

[0025] Step 2, Electrode Preparation: First, the shavings of residual material are pressed to obtain an electrode block, and then the electrode block is welded to obtain a consumable electrode. This specifically includes the following steps: Step 2.1, pressing of the scrap electrode blocks: The weighed sponge zirconium and the above scrap are pressed together to form a single electrode block weighing 60kg, with a specification of Φ200mm×400mm, and a pressing force of 2800t. A total of 30 electrode blocks are pressed. Step 2.2 Electrode welding: The shavings of the electrode block obtained in step 2.1 are welded into two consumable electrodes in a vacuum plasma welding box (one consumable electrode consists of 15 electrode blocks). The electrode specifications are Φ200mm×6000mm, each electrode weighs 1200kg, the welding current is 460A, and the cooling time after welding is 1h. Step 3, Electron Beam Melting: Step 3.1, Primary Refining and Melting: The two consumable electrodes obtained in Step 2.2 are melted in an electron beam furnace to obtain two primary ingots. The vacuum degree before melting is ≤0.05Pa, the pressure rise rate before melting is ≤0.1Pa / min, the crystallizer diameter is Φ200mm, and the specifications of the primary ingots after melting are Φ200mm×5800mm. The melting speed is set to 1.2kg / min and the melting power is 120kW. Step 3.2, Secondary Purification and Smelting: The two primary ingots obtained in Step 3.1 are smelted again in an electron beam furnace to obtain two intermediate ingots (Ingot 1 and Ingot 2). The vacuum degree before smelting is ≤0.05Pa, the pressure rise rate before melting is ≤0.1Pa / min, the crystallizer diameter is Φ200mm, and the specifications of the intermediate ingots after smelting are Φ200mm×5800mm. The smelting speed is set to 1.3kg / min and the smelting power is 130kW. Step 3.3: Samples were taken from the intermediate ingots obtained after two purification and smelting processes, and the content of Sn, Fe and Cr elements was analyzed. The results are shown in Table 1.

[0026] Table 1 Chemical composition of intermediate ingots after electron beam purification and smelting Step 4, Vacuum consumable arc melting: The two intermediate ingots prepared in Step 3 are melted in a vacuum consumable arc furnace to form one ingot. The melting process includes the following steps: Step 4.1: The two intermediate ingots obtained in Step 3 are melted once in a 3t vacuum consumable arc furnace to obtain one ingot. The vacuum degree before melting is ≤0.3Pa, the pressure rise rate before melting is ≤0.1Pa / min, the crystallizer diameter is Φ550mm, and the ingot size after melting is Φ550mm×1550mm. The melting speed is set to 16kg / min, the melting voltage is 34V, the melting current is 17kA, the stirring magnetic field strength is 8Gs, and the stirring is bidirectional. The cooling time after melting is 7h. The inlet and outlet water temperatures of the crucible cooling water are 35℃ and 40℃, respectively. Step 4.2: The nuclear-grade zirconium alloy scrap ingot obtained in Step 4.2 was sampled and analyzed. The results are shown in Table 2 below.

[0027] Table 2 Chemical composition of nuclear-grade zirconium alloy scrap ingots As can be seen from the above embodiments, the technical solution provided in this embodiment perfectly solves the problem of transforming high-content Sn, Fe, and Cr elements in zirconium alloys into low-content Sn, Fe, and Cr elements; and by adding two electron beam melting processes before the existing vacuum consumable melting, and by appropriately reducing the melting speed and increasing the vacuum requirement during electron beam melting, the purification effect is enhanced.

[0028] Example 2 Based on Example 1, the difference is that the residue screened in step 1 also includes Nb element. The Nb content is typically between 0.5 wt% and 2.5 wt%, preferably 1.0 wt%. To further verify the versatility of the recycling and smelting method provided by this invention, the same experiment as in Example 1 was conducted: In the intermediate ingot obtained after electron beam purification and smelting, the contents of Sn, Fe, and Cr elements were the same as in Example 1. The Nb content at different sampling locations was as follows: Ingot #1: 1.00 wt% (top), 1.02 wt% (middle), 1.03 wt% (bottom); Ingot #2: 1.00 wt% (top), 1.01 wt% (middle), 1.00 wt% (bottom). In the nuclear-grade zirconium alloy residue ingot obtained after vacuum arc melting, the contents of Sn, Fe, and Cr elements were the same as in Example 1, and the Nb content at different sampling locations did not decrease.

[0029] Example 3 This embodiment provides a method for recycling and smelting zirconium alloy scrap, specifically including the following steps: Step 1: Screen the residue and clean the surface of the screened residue: Nuclear-grade zirconium alloy block scrap with Sn content of 0.7wt%, Fe content of 0.7wt%, and Cr content of 0.3wt% was screened. The surface of the scrap was cleaned by pre-cleaning, pickling, and ultrapure water cleaning to remove impurities and oxide layers from the surface of the scrap, thereby improving the purity and corrosion resistance of the zirconium alloy scrap. The specific cleaning process is the same as in Example 1. Step 2, Electrode preparation: The blocky residue is directly welded to obtain a consumable electrode. The specific process is as follows: The blocky residue is welded into two consumable electrodes in a vacuum plasma welding box. Each electrode weighs 1200 kg, the welding current is 460 A, and the cooling time after welding is 1 h. Step 3, Electron Beam Melting: Step 3.1, Two-stage purification and smelting: The two consumable electrodes obtained in Step 2 are smelted twice in an electron beam furnace to obtain two secondary ingots. The dimensions of the secondary ingots after smelting are Φ260mm×4000mm. The process parameters for each electron beam smelting are set as follows: vacuum degree before smelting ≤0.05Pa, pressure rise rate before smelting ≤0.1Pa / min, crystallizer diameter is Φ260mm, smelting speed is set to 1.5kg / min, and smelting power is set to 130kW. Step 3.2, Third Refining and Smelting: The two primary ingots obtained in Step 3.1 are smelted again in an electron beam furnace to obtain two intermediate ingots (Ingot 1 and Ingot 2). The vacuum degree before smelting is ≤0.05Pa, the pressure rise rate before melting is ≤0.1Pa / min, the crystallizer diameter is Φ260mm, and the specifications of the intermediate ingots after smelting are Φ260mm×3000mm. The smelting speed is set to 1.5kg / min and the smelting power is 170kW. Step 3.3: Samples were taken from the intermediate ingots obtained after three purification and smelting processes, and the content of Sn, Fe and Cr elements was analyzed. The results are shown in Table 3.

[0030] Table 3 Chemical composition of intermediate ingots after electron beam purification and smelting Step 4, Vacuum consumable arc melting: The two intermediate ingots prepared in Step 3 are melted twice in a vacuum consumable arc furnace to form one ingot. The melting process includes the following steps: Step 4.1, First Melting: The two intermediate ingots obtained in Step 3 are first melted in a 3t vacuum consumable arc furnace to obtain one ingot. The vacuum degree before melting is ≤0.3Pa, the pressure rise rate before melting is ≤0.1Pa / min, the crystallizer diameter is Φ550mm, and the ingot size after melting is Φ550mm×1550mm. The melting speed is set to 18kg / min, the melting current is 19kA, the melting voltage is 35V, the stirring magnetic field strength is 10Gs, and bidirectional stirring is used. The cooling time after melting is 7h. The inlet and outlet water temperatures of the crucible cooling water are 30℃ and 39℃, respectively. Step 4.2, Second Melting: The ingot obtained in Step 4.1 was subjected to a second melting in a 3t vacuum consumable arc furnace, resulting in one nuclear-grade zirconium alloy scrap ingot. The vacuum degree before melting was ≤0.3Pa, the pressure rise rate before melting was ≤0.1Pa / min, the crystallizer diameter was Φ650mm, and the specifications of the nuclear-grade zirconium alloy scrap ingot after melting were Φ650mm×1200mm. The melting rate was set to 22kg / min, the melting current was 23kA, the melting voltage was 36V, the stirring magnetic field strength was 16Gs, and bidirectional stirring was used. The cooling time after melting was 8h. The inlet and outlet water temperatures of the crucible cooling water were 38℃ and 45℃, respectively. Step 4.3: Sample and analyze the nuclear-grade zirconium alloy scrap ingot obtained in Step 4.2. The results are shown in Table 4 below.

[0031] Table 4 Chemical composition of nuclear-grade zirconium alloy scrap ingots As can be seen from the above embodiments, the technical solution provided in this embodiment perfectly solves the problem of transforming high-content Sn, Fe, and Cr elements in zirconium alloys into low-content Sn, Fe, and Cr elements; and by adding three electron beam melting processes before the existing vacuum consumable melting, and by appropriately reducing the melting speed and increasing the vacuum requirement during electron beam melting, the purification effect is enhanced.

[0032] Example 4 This embodiment provides a method for recycling and smelting zirconium alloy scrap, specifically including the following steps: Step 1: Screen the residue and clean the surface of the screened residue: Nuclear-grade zirconium alloy scrap and block scrap with Sn content of 1.4wt%, Fe content of 0.22wt%, and Cr content of 0.13wt% were selected. The surface of the scrap was cleaned using the same cleaning method as in Example 1. Step 2, Electrode Preparation: Consumable electrodes are prepared using the nuclear-grade zirconium alloy scrap and block scrap, respectively, specifically including the following steps: Step 2.1, Electrode pressing of scrap material: The weighed sponge zirconium and the above scrap material are pressed together to form an electrode block weighing 60kg each, with a size of Φ200mm×400mm, a pressing force of 2800t, and a total of 20 electrode blocks are pressed. Step 2.2, Electrode Welding: The shavings of electrode blocks obtained in Step 2.1 are welded into one electrode in a vacuum plasma welding box, consisting of 20 electrode blocks (the entire electrode has a size of Φ200mm×8000mm). The welding current is 460A, and the cooling time after welding is 1 hour. It should be noted that in actual pressing, the density of the electrode blocks obtained by pressing the shavings is 70%~80% of the density of the electrode blocks obtained by pressing the blocky residue, so the length of the electrode here is relatively long. The blocky residue is then welded into an electrode with a size of Φ200mm×4000mm using an argon arc welding machine, weighing 1200kg. Step 3, Electron Beam Melting: Step 3.1, First purification and smelting: The two electrodes obtained in step 2.2 are smelted twice in an electron beam furnace to obtain two primary ingots. The vacuum degree before smelting is ≤0.05Pa, the pressure rise rate before smelting is ≤0.1Pa / min, the crystallizer diameter is Φ260mm, and the size after smelting is Φ260mm×3400mm. The smelting speed is set to 1.5kg / min and the smelting power is 150kW. Step 3.2, Second Purification and Melting: The two primary ingots obtained in Step 3.1 are melted again in an electron beam furnace to obtain two intermediate ingots (Ingot 1 and Ingot 2). The vacuum degree before melting is ≤0.05Pa, the pressure rise rate before melting is ≤0.1Pa / min, the crystallizer diameter is Φ300mm, and the specifications of the intermediate ingots after melting are Φ300mm×2600mm. The melting speed is set to 1.5kg / min and the melting power is 170kW. Step 3.3: Samples were taken from the intermediate ingots obtained after two purification and smelting processes, and the content of Sn, Fe and Cr elements was analyzed. The results are shown in Table 5.

[0033] Table 5 Chemical composition of intermediate ingots after electron beam purification Step 4, Vacuum consumable arc melting: The two intermediate ingots prepared in Step 3 are melted twice in a vacuum consumable arc furnace to produce one ingot. The melting process includes the following steps: Step 4.1, First Melting: The two intermediate ingots obtained in Step 3 are first melted in a 3t vacuum consumable arc furnace to obtain one primary ingot. The vacuum degree before melting is ≤0.3Pa, the pressure rise rate before melting is ≤0.1Pa / min, the crystallizer diameter is Φ550mm, and the specifications of the ingot after melting are Φ550mm×1550mm. The melting rate is set to 18kg / min, the melting current is 19kA, the melting voltage is 35V, the stirring magnetic field strength is 10Gs, and bidirectional stirring is used. The cooling time after melting is 7h. The inlet and outlet water temperatures of the crucible cooling water are 33℃ and 43℃, respectively. Step 4.2, Second Melting: The one primary ingot obtained in Step 4.1 is subjected to a second melting in a 3t vacuum consumable arc furnace to obtain one ingot. The vacuum degree before melting is ≤0.3Pa, the pressure rise rate before melting is ≤0.1Pa / min, the crystallizer diameter is Φ650mm, and the specifications of the ingot after melting are Φ650mm×1200mm. The melting rate is set to 22kg / min, the melting current is 23kA, the melting voltage is 36V, the stirring magnetic field strength is 16Gs, and bidirectional stirring is used. The cooling time after melting is 8h. The inlet and outlet water temperatures of the crucible cooling water are 35℃ and 45℃, respectively. Step 4.3: Take samples of the ingots obtained in Step 4.2 and analyze their chemical composition. The results are shown in Table 6 below.

[0034] Table 6 Chemical composition of nuclear-grade zirconium alloy scrap ingots Example 5 This embodiment provides a method for recycling and smelting zirconium alloy scrap, specifically including the following steps: Step 1: Screen the residue and clean the surface of the screened residue: Nuclear-grade zirconium alloy scrap and block scrap with Sn content of 1.4 wt%, Fe content of 0.22 wt%, and Cr content of 0.13 wt% were screened. It should be noted that the scrap also contains Nb element with a content of 0.3 wt%. The surface of the scrap was cleaned using the same cleaning method as in Example 1. Step 2, Electrode Preparation: The nuclear-grade zirconium alloy scrap and block scrap are respectively prepared into consumable electrodes, specifically including the following steps: Step 2.1, Electrode pressing of scrap material: The weighed sponge zirconium and the above scrap material are pressed together to form an electrode block weighing 60kg each, with a size of Φ200mm×400mm, a pressing force of 2800t, and a total of 20 electrode blocks are pressed. Step 2.2, Electrode Welding: The shavings of electrode scrap obtained in Step 2.1 are welded into one electrode in a vacuum plasma welding box, consisting of 20 electrode blocks (the entire electrode has a size of Φ200mm×8000mm). The welding current is 460A, and the cooling time after welding is 1 hour. The shavings are then welded into an electrode with a size of Φ200mm×4000mm using an argon arc welding machine, weighing 1200kg. Step 3, Electron Beam Melting: Step 3.1, First purification and smelting: The two electrodes obtained in step 2.2 are smelted twice in an electron beam furnace to obtain two primary ingots. The vacuum degree before smelting is ≤0.05Pa, the pressure rise rate before smelting is ≤0.1Pa / min, the crystallizer diameter is Φ260mm, and the size after smelting is Φ260mm×3400mm. The smelting speed is set to 1.4kg / min and the smelting power is 150kW. Step 3.2, Second Purification and Melting: The two primary ingots obtained in Step 3.1 are melted again in an electron beam furnace to obtain two intermediate ingots (Ingot 1 and Ingot 2). The vacuum degree before melting is ≤0.05Pa, the pressure rise rate before melting is ≤0.1Pa / min, the crystallizer diameter is Φ300mm, and the specifications of the intermediate ingots after melting are Φ300mm×2600mm. The melting rate is set to 1.5kg / min and the melting power is 170kW. Step 3.3: Samples were taken from the intermediate ingots obtained after two purification and smelting processes, and the content of Sn, Fe and Cr elements was analyzed. The results are shown in Table 7.

[0035] Table 7 Chemical composition of ingots after electron beam purification Step 4, Vacuum consumable arc melting: The two intermediate ingots prepared in Step 3 are melted twice in a vacuum consumable arc furnace to produce one ingot. The melting process includes the following steps: Step 4.1, First Melting: The two intermediate ingots obtained in Step 3 are melted for the first time in a 3t vacuum consumable arc furnace to obtain one primary ingot. The vacuum degree before melting is ≤0.3Pa, the pressure rise rate before melting is ≤0.1Pa / min, the crystallizer diameter is Φ550mm, and the specifications of the ingot after melting are Φ550mm×1550mm. The melting speed is set to 18kg / min, the melting current is 19kA, the melting voltage is 35V, the stirring magnetic field strength is 10Gs, and bidirectional stirring is used. The cooling time after melting is 7h. The inlet and outlet water temperatures of the crucible cooling water are 33℃ and 43℃, respectively. Step 4.2, Second Melting: The one primary ingot obtained in Step 4.1 is subjected to a second melting in a 3t vacuum consumable arc furnace to obtain one ingot. The vacuum degree before melting is ≤0.3Pa, the pressure rise rate before melting is ≤0.1Pa / min, the crystallizer diameter is Φ650mm, and the specifications of the ingot after melting are Φ650mm×1200mm. The melting rate is set to 22kg / min, the melting current is 23kA, the melting voltage is 36V, the stirring magnetic field strength is 16Gs, and bidirectional stirring is used. The cooling time after melting is 8h. The inlet and outlet water temperatures of the crucible cooling water are 35℃ and 45℃, respectively. Step 4.3: Take samples of the ingots obtained in Step 4.2 and analyze their chemical composition. The results are shown in Table 8 below.

[0036] Table 8 Chemical composition of nuclear-grade zirconium alloy scrap ingots It should be noted that by adding 0.7% Nb, 0.5% Sn, and 0.07% Fe to the above-mentioned residual ingot, and then performing two vacuum arc melting processes, a finished zirconium alloy ingot with 1.0% Nb, 0.8% Sn, and 0.3% Fe can be prepared, which can meet industrial requirements.

[0037] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0038] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for recycling smelting of zirconium alloy scrap, characterized by, The application discloses a recycling smelting method of nuclear-grade zirconium alloy scrap, which comprises the following steps: screening the nuclear-grade zirconium alloy scrap, preparing electrodes, electron beam smelting, and vacuum self-consumption arc smelting.

2. The method of recycling a zirconium alloy scrap according to claim 1, wherein Specifically, the method comprises the following steps: Step 1: screening the nuclear-grade zirconium alloy scrap and pretreating the nuclear-grade zirconium alloy scrap; Step 2: preparing electrodes by using the nuclear-grade zirconium alloy scrap; Step 3: electron beam smelting the electrodes; Step 4: vacuum self-consumption arc smelting the intermediate ingots. The nuclear-grade zirconium alloy scrap comprises scrap and / or block scrap.

4. The recycling smelting method of the zirconium alloy scrap according to claim 3, wherein if the nuclear-grade zirconium alloy scrap is all scrap, the scrap is pressed to obtain electrode blocks, and the electrode blocks are welded to obtain the self-consumption electrodes; if the nuclear-grade zirconium alloy scrap is all block scrap, the block scrap is directly welded to obtain the self-consumption electrodes; and if the nuclear-grade zirconium alloy scrap is a mixture of scrap and block scrap, the self-consumption electrodes are prepared respectively. In step 1, the nuclear-grade zirconium alloy scrap contains 0.7wt%-1.4wt% of Sn, 0.5wt%-1.0wt% of Fe and 0.1wt%-0.5wt% of Cr.

3. The method of recycling a zirconium alloy scrap according to claim 2, wherein In step 4, the nuclear-grade zirconium alloy scrap ingot contains 0.1wt%-0.5wt% of Sn, 0.1wt%-0.5wt% of Fe and 0.1wt%-0.5wt% of Cr. In step 3, the process parameters of each electron beam smelting are set as follows: the vacuum degree before smelting is less than or equal to 0.05 Pa, the pressure rising rate before smelting is less than or equal to 0.1 Pa / min, the diameter of the crystallizer is 200mm-300mm, the smelting speed is 1.2kg / min-1.5kg / min, and the smelting power is 120kW-170kW. In step 4, the process parameters of each vacuum self-consumption arc smelting are set as follows: the vacuum degree before smelting is less than or equal to 0.3 Pa, the pressure rising rate before smelting is less than or equal to 0.1 Pa / min, the diameter of the crystallizer is 300mm-650mm, the smelting speed is 16kg / min-22kg / min, the smelting voltage is 34V-36V, the smelting current is 17kA-23kA, the smelting stirring magnetic field intensity is 8Gs-16Gs, and the smelting is bidirectional stirring. The nuclear-grade zirconium alloy scrap ingot is cooled out of the furnace in an inert gas state, and when the ingot is cooled, the inlet water temperature of the crystallizer cooling water is 30℃-38℃, and the outlet water temperature is 39℃-45℃.

10. Application of the recycling smelting method of the zirconium alloy scrap according to any one of claims 1-9 in recycling of nuclear-grade zirconium alloy scrap.

5. The method of recycling a zirconium alloy scrap according to claim 2, wherein ​ 6. The method of recycling a zirconium alloy scrap according to claim 5, wherein ​ 7. The method of claim 2, wherein the zirconium alloy scrap is melted in a vacuum induction furnace. ​ ​ 8. The method of recycling a zirconium alloy scrap according to claim 2, wherein ​ ​ 9. The method of recycling a zirconium alloy scrap according to claim 8, wherein ​ ​

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