A method for producing r60702 ingot by var melting using r60700 scrap

Abstract

The application discloses a method for preparing R60702 ingot material by VAR smelting using R60700 waste, which comprises the following steps: 1, collecting and storing R60700 block-shaped residual waste, and then performing sand blasting and pickling; 2, obtaining R60700 waste through element detection; 3, calculating the proportion of ingredients; 4, pressing the powder-shaped ZrO2 and sponge zirconium into electrode blocks; 5, welding the electrode blocks and placing them in the core, wrapping the outer side with strip-shaped R60700 waste, and welding and bundling with waistband-shaped R60700 waste; and 6, obtaining R60702 ingot material through VAR smelting. The application adopts a "heart-wrapped" material process, utilizes R60700 waste to wrap the electrode blocks in the core and welds the electrode blocks into consumable electrodes for smelting, realizes accurate control of the content of O element, obtains R60702 ingot material with components meeting the standard, realizes large recycling of R60700 waste, and can be popularized to the alloy waste recycling field.

Description

Technical Field

[0001] This invention belongs to the field of metal material processing technology, specifically relating to a method for preparing R60702 ingots using R60700 waste through VAR smelting. Background Technology

[0002] Zirconium and zirconium alloys possess excellent mechanical, thermal transfer, and corrosion resistance properties, making them superior corrosion-resistant structural materials in the petrochemical and nuclear energy fields. Industrial zirconium products are widely used in various corrosion-resistant process equipment, primarily including pressure vessels, heat exchangers, pipes, tanks, shafts, agitators, nuclear machinery, valves, pumps, sprayers, trays, demisters, and tower linings. Therefore, the strategic importance of zirconium and zirconium alloys is self-evident. Due to their wide range of applications, zirconium and zirconium alloys generate a large amount of waste during industrial production. The main types of waste are plate trimmings, ingot risers, bar ends, and other bulk waste. Given the resource and strategic importance of zirconium and zirconium alloys, the recycling and reuse of zirconium waste is of great significance.

[0003] The most widely used grades of zirconium and zirconium alloys are R60700, R60702, and R60705. The corresponding grades in the national standard GB / T26314-2010 are Zr-1, Zr-3, and Zr-5. In the market, the American standard ASME SB-551 / 551M is often used as the evaluation standard. In this standard, the oxygen content requirement for R60700 is O < 0.10 wt.%, and the oxygen content requirement for R60702 is 0.10 wt.% ≤ O < 0.16 wt.%. R60700 and R60702 have similar corrosion resistance. R60700, due to its lower oxygen content, has slightly lower strength and hardness, but better plasticity and ductility. It is mainly processed into products such as pipes, wires, and thin plates. These products explicitly prohibit the addition of residual or waste materials to prevent inclusions and oxygenation from affecting performance. In contrast, R60702 products have a wider range of applications and stronger market demand. Product types include medium and heavy plates, forgings, various specifications of bars, discs, and irregularly shaped parts. Some R60702 products explicitly allow the addition of a certain proportion of residual or waste materials, and some civilian products even allow 100% waste materials as raw materials, thus enabling the effective utilization of R60702 waste generated in daily life. A large amount of R60700 waste accumulated in the market cannot be utilized. Even if it is directly recycled and remelted into ingots, its O content is generally slightly higher than the R60700 standard requirements. Even if the composition requirements of R60700 ingots are met, it is still difficult to turn it into products for sale. Therefore, it is extremely important to effectively recycle and utilize R60700 waste.

[0004] Chemical composition analysis of R60700 waste revealed that its O content was <0.08 wt.%, while that of R60702 was 0.10–0.16 wt.%. If R60700 zirconium waste could be recycled into R60702 ingots meeting ASME SB-551 / 551M requirements, and then processed into medium-thick plates or bar forgings through forging or rolling, the R60700 waste could be effectively utilized. However, based on market research and extensive literature review, there are currently no readily available technical solutions in this field, either domestically or internationally, for recycling and smelting R60700 waste into R60702 ingots to achieve the A+B recycling process to grade C (A+B→C). Summary of the Invention

[0005] The technical problem this invention aims to solve is to address the shortcomings of the prior art by providing a method for preparing R60702 ingots using R60700 waste through VAR melting. This method employs a "core-wrapping" fabrication process. By precisely calculating the amount of ZrO2 added, ZrO2 is uniformly mixed with sponge zirconium and pressed into electrode blocks. Then, R60700 waste is used to wrap the electrode blocks around the core and welded to form consumable electrodes for VAR melting. This allows for precise control of the oxygen content, resulting in R60702 ingots with a composition that meets AME SB-551 / SB-551M standards. This solves the problem of the waste caused by the inability to recycle existing R60700 waste.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for preparing R60702 ingots using R60700 waste through VAR smelting, characterized in that the method includes the following steps:

[0007] Step 1: Strictly classify, collect, and store the blocky waste materials generated during the production of R60700 grade products, including plate edges, rod heads, and risers. Then, sandblast and pickle the classified and stored blocky waste materials until the surface is free of contamination and turns silvery-white.

[0008] Step 2: Use a PMI handheld spectrometer to perform elemental analysis on the blocky waste material processed in Step 1, and remove other grades of metallic foreign matter to obtain R60700 waste material;

[0009] Step 3: Based on the O mass content in the target product R60702 ingot, calculate the required proportions of R60700 waste, sponge zirconium, and ZrO2.

[0010] Step 4: According to the proportions calculated in Step 3, add powdered ZrO2 to the sponge zirconium for mixing and press it into an electrode block;

[0011] Step 5: After splicing and welding the electrode blocks pressed in Step 4, place them in the core, then wrap the outer side with the strip-shaped R60700 waste from Step 2, and use the belt-shaped R60700 waste from the R60700 waste to weld and bind them, thus obtaining the consumable electrode used for VAR melting.

[0012] Step 6: Perform a VAR melting process on the consumable electrode obtained in Step 5 to obtain a primary ingot. Then, weld the two primary ingots together in the furnace and perform a second VAR melting process and a third VAR melting process to obtain R60702 ingot material.

[0013] This invention uses R60700 waste, sponge zirconium, and ZrO2 as raw materials. First, based on the O mass content in the target product R60702 ingot, the required proportions of R60700 waste, sponge zirconium, and ZrO2 are calculated. Then, sponge zirconium and ZrO2 are mixed evenly and pressed into electrode blocks. Next, R60700 waste is used to wrap the electrode blocks around the core to weld consumable electrodes. Through an innovative "core-wrapped" fabric welding process, R60702 ingots with compositions meeting AME SB-551 / SB-551M standards are prepared through three VAR melting processes. This successfully transforms R60700 waste, which is difficult to use directly, into R60702 ingots with high demand, achieving technological innovation in the field of A+B recycling to become grade C (A+B→C).

[0014] To address the challenge of precisely controlling oxygen (O) content in materials prone to oxidation during waste recycling and smelting, this invention fixes powdered ZrO2 into the center of R60700 waste using sponge zirconium, precisely controlling the O content in the raw material and achieving accurate O enrichment during the recycling and smelting process. Furthermore, unlike conventional EB (Extractive Electrode) smelting and recycling processes where powdered and blocky raw materials are mixed or layered and then directly smelted without pressing and welding electrode blocks, this invention uses a "core-wrapped" material preparation method to prepare consumable electrodes for VAR (Vacuum-Acid Recycling) smelting. This enables the preparation of high-oxygen R60702 ingots from low-oxygen R60700 waste, and allows for precise control of O content by adjusting the process according to different product requirements.

[0015] The above-mentioned method for preparing R60702 ingots using R60700 waste through VAR smelting is characterized in that, in step three, according to the standard AME SB-551 / SB-551M, the O mass content in R60702 is specified as 0.10% to 0.16%, and the O mass content in the target product R60702 ingot is determined to be 0.125%, and the calculation formula is shown in the following formula (1):

[0016]

[0017] Where A is the O mass content in the target product R60702 ingot, w1 is the O mass content in ZrO2, w2 is the average O mass content in sponge zirconium, w3 is the average O mass content in R60700 waste, all in %; m1 is the weight of ZrO2 added, m2 is the weight of sponge zirconium added, and m3 is the weight of R60700 waste added.

[0018] The above-mentioned method for preparing R60702 ingots using R60700 waste through VAR smelting is characterized in that, in step six, samples are taken from the upper, middle and lower parts of the circumference of the R60702 ingot and chemical composition is tested, and the determination is made according to the AME SB-551 / SB-551M standard.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. This invention adopts a "core-wrapping" fabric process. By accurately calculating the amount of ZrO2 added, ZrO2 is mixed with sponge zirconium and pressed into an electrode block. Then, R60700 waste is used to wrap the electrode block in the core and weld it to form a consumable electrode for VAR melting. This achieves precise control of the O element content and obtains R60702 ingot material whose composition meets the AME SB-551 / SB-551M standard.

[0021] 2. This invention enables the large-scale recycling and utilization of R60700 waste (approximately 75% of the total amount), effectively saving resources, turning waste into treasure, solving the current situation where R60700 waste cannot be recycled and is wasted, realizing the full utilization of zirconium metal resources, which helps to alleviate the shortage of zirconium metal resources, save mineral energy consumption, and reduce environmental pollution.

[0022] 3. In the existing zirconium waste recycling field, it is common to recycle grade A to grade A (A→A). However, there is no technical solution to refer to for recycling A+B to grade C (A+B→C). The method of this invention completes the process of R60700 waste + sponge zirconium + ZrO2 → R60702, realizing the recycling of A+B to grade C (A+B→C), and completing the technological innovation in this field.

[0023] 4. The process route of this invention, which recycles A+B into grade C (A+B→C), can be extended to the recycling and remelting of various precious metal alloy wastes, laying a technical foundation for the subsequent development of (A+B+C+…→N) processes.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 This is a photograph of powdered ZrO2 added to sponge zirconium in Example 1 of the present invention.

[0026] Figure 2 This is a physical image of the electrode block in Embodiment 1 of the present invention.

[0027] Figure 3 This is a physical diagram of the process of preparing the consumable electrode in Embodiment 1 of the present invention.

[0028] Figure 4 The images show actual photos of the R60702 ingots prepared in Examples 1 and 2 of this invention. Detailed Implementation

[0029] Example 1

[0030] This embodiment includes the following steps:

[0031] Step 1: Strictly classify, collect, and store the blocky waste materials generated during the production of R60700 grade products, including plate edges, rod heads, and risers. Then, sandblast and pickle the classified and stored blocky waste materials until the surface is free of contamination and turns silvery-white.

[0032] Step 2: Use a PMI handheld spectrometer to perform elemental analysis on the blocky waste material processed in Step 1, and remove other grades of metallic foreign matter to obtain R60700 waste material;

[0033] Step 3: According to the standard AME SB-551 / SB-551M, the O content in R60702 is specified to be 0.10% to 0.16%. The target product R60702 ingot has an O content of 0.125%. The required proportions of R60700 waste, sponge zirconium, and ZrO2 are calculated. The calculation formula is shown in the following formula (1):

[0034]

[0035] Where A is the O mass content in the target product R60702 ingot (0.125%), w1 is the O mass content in ZrO2 (26%), w2 is the average O mass content in sponge zirconium (0.0505%), w3 is the average O mass content in R60700 waste (0.05%–0.08%), m1 is the added weight of ZrO2, m2 is the added weight of sponge zirconium, and m3 is the added weight of R60700 waste.

[0036] The calculated ingredient ratio includes 10 electrode blocks, each weighing 82.512 kg. The O element content in the electrode block is 0.217%, of which sponge zirconium weighs 82 kg and ZrO2 weighs 0.512 kg. The specific ingredients are shown in Table 1.

[0037] Table 1

[0038] Material type O mass content / % Single electrode block feed weight / kg <![CDATA[ZrO2]]> 26 0.512 sponge zirconium 0.0505 82 Ingredient Value 0.217 /

[0039] Step 4: Based on the proportions calculated in Step 3, add powdered ZrO2 to the sponge zirconium for mixing. During loading, add the powdered ZrO2 in three layers into the press mold and spread it evenly on the sponge zirconium. This avoids the loss of ZrO2 caused by conventional mixing methods, such as spillage, flying, or sticking to the walls, which could lead to low O content or uneven O distribution. Figure 1 As shown, it is pressed into an electrode block, as... Figure 2 As shown, a total of 10 electrode blocks with a diameter × height of Φ220mm × 350mm were obtained;

[0040] Step 5: After splicing and welding the 10 electrode blocks pressed in Step 4, place them in the core. Then wrap the outer side with the strip-shaped R60700 waste from Step 2, and use the M-state (annealed state) belt-shaped R60700 waste from R60700 to weld and bind it, thus obtaining the consumable electrode used for VAR melting.

[0041] Specifically, such as Figure 3 As shown, firstly, strip-shaped R60700 scrap is used to fill the area to a height h = 130mm. Then, 10 electrode blocks are spliced ​​together, welded, and placed in the core. The upper part is then filled with strip-shaped R60700 scrap again to a height h = 130mm, so that the outer side of the electrode blocks is wrapped with strip-shaped R60700 scrap. Viewed from the end face, the electrode blocks are positioned at the very "core" of the electrode. Then, external plasma welding is used, employing M-state waistband-shaped R60700 scrap for welding and binding. The weld points are selected from strip-shaped R6070... For the area where the 0-waste material and the M-state belt-shaped R60700 waste material are attached, avoid welding at the sharp corners. After welding, the severely oxidized areas such as blue or gray on the surface of the weld should be polished until the metal color is exposed. A total of 1080kg of strip-shaped R60700 waste material is wrapped around the outside of 10 electrode blocks with a diameter × height of Φ220mm × 350mm, resulting in a consumable electrode with a total weight of 1900kg ± 5kg, a length L = 3500mm, and a diameter Φ ≤ 430mm.

[0042] Step Six: Perform a single VAR melting process on the two consumable electrodes obtained in Step Five to obtain a primary ingot. Then, weld the two primary ingots in a furnace and perform a second and third VAR melting process sequentially to obtain R60702 ingot material. Figure 4 As shown, the crucible specifications used in each VAR melting process were Φ560mm, Φ640mm, and Φ720mm, respectively. The process parameters are shown in Table 2 below:

[0043] Table 2

[0044] Smelting parameters A VAR melting Secondary VAR melting Three VAR melting Pre-melting vacuum level / Pa <![CDATA[≤5×10 0 ]]> <![CDATA[≤5×10 0 ]]> <![CDATA[≤5×10 0 ]]> Pre-melting leakage rate / Pa / min ≤0.9 ≤0.9 ≤0.9 Stable arc stirring reversal frequency / second / time 15 20 25 Maximum vacuum level during steady-state phase / Pa ≤35 ≤35 ≤15 Furnace cooling time / min ≥400 ≥440 ≥500

[0045] Sampling was performed on the R60702 ingot prepared in this embodiment at three points around its circumference: top, middle, and bottom. This included both block and shaving samples. The chemical composition was analyzed and determined according to AME SB-551 / SB-551M standards. The results are shown in Table 3 below.

[0046] Table 3

[0047]

[0048]

[0049] As can be seen from Table 3, the mass content of O and other impurity elements in the R60702 ingot prepared in this embodiment meets the requirements of R60702 in the ASME SB-551 / 551M standard, and the O element is evenly distributed.

[0050] Example 2

[0051] This embodiment includes the following steps:

[0052] Step 1: Strictly classify, collect, and store the blocky waste materials generated during the production of R60700 grade products, including plate edges, rod heads, and risers. Then, sandblast and pickle the classified and stored blocky waste materials until the surface is free of pollution and turns silvery-white.

[0053] Step 2: Use a PMI handheld spectrometer to perform elemental analysis on the blocky waste material processed in Step 1, and remove other grades of metallic foreign matter to obtain R60700 waste material;

[0054] Step 3: According to the standard AME SB-551 / SB-551M, the O content in R60702 is specified to be 0.10% to 0.16%. The target product R60702 ingot has an O content of 0.125%. The required proportions of R60700 waste, sponge zirconium, and ZrO2 are calculated. The calculation formula is shown in the following formula (1):

[0055]

[0056] Where A is the O mass content in the target product R60702 ingot (0.125%), w1 is the O mass content in ZrO2 (26%), w2 is the average O mass content in sponge zirconium (0.0505%), w3 is the average O mass content in R60700 waste (0.05%–0.08%), m1 is the added weight of ZrO2, m2 is the added weight of sponge zirconium, and m3 is the added weight of R60700 waste.

[0057] The calculated ingredient ratio includes 10 electrode blocks, each weighing 65.685 kg. The O element content in the electrode block is 0.32%, of which sponge zirconium weighs 65 kg and ZrO2 weighs 0.685 kg. The specific ingredients are shown in Table 4.

[0058] Table 4

[0059]

[0060]

[0061] Step 4: According to the proportion of ingredients calculated in Step 3, add powdered ZrO2 to sponge zirconium for mixing. When feeding, add powdered ZrO2 to the press mold in 3 layers and spread it evenly on sponge zirconium. This avoids the loss of ZrO2 caused by conventional mixing methods, such as spillage, flying, and sticking to the wall, which would result in low O element or uneven O element distribution. Press it into electrode blocks and obtain a total of 10 electrode blocks with a diameter × height of Φ220mm × 350mm.

[0062] Step 5: After splicing and welding the 10 electrode blocks pressed in Step 4, place them in the core. Then wrap the outer side with the strip-shaped R60700 waste from Step 2, and use the M-state (annealed state) belt-shaped R60700 waste from R60700 to weld and bind it, thus obtaining the consumable electrode used for VAR melting.

[0063] Specifically, first, strip-shaped R60700 scrap is used to fill the area to a height h = 130mm. Then, 10 electrode blocks are spliced ​​together, welded, and placed in the core. The upper part is then filled with strip-shaped R60700 scrap to a height h = 130mm, so that the outer side of the electrode blocks is wrapped with strip-shaped R60700 scrap. Viewed from the end face, the electrode blocks are positioned at the very "core" of the electrode. Then, external plasma welding is used, employing M-state waistband-shaped R60700 scrap for welding and binding. The weld points are selected from strip-shaped R6070... For the area where the 0-waste material and the M-state belt-shaped R60700 waste material are attached, avoid welding at the sharp corners. After welding, the severely oxidized areas such as blue or gray on the surface of the weld should be polished until the metal color is exposed. A total of 2000 kg of strip-shaped R60700 waste material is wrapped around the outside of 10 electrode blocks with a diameter × height of Φ220 mm × 350 mm, resulting in a consumable electrode with a total weight of 2657 kg ± 5 kg, a length L = 3500 mm, and a diameter Φ ≤ 480 mm.

[0064] Step Six: Perform a single VAR melting process on the two consumable electrodes obtained in Step Five to obtain a primary ingot. Then, weld the two primary ingots in a furnace and perform a second and third VAR melting process sequentially to obtain R60702 ingot material. Figure 4As shown, the crucible specifications used in each VAR melting process were Φ560mm, Φ640mm, and Φ720mm, respectively. The process parameters are shown in Table 5 below:

[0065] Table 5

[0066] Smelting parameters A VAR melting Secondary VAR melting Three VAR melting Pre-melting vacuum level / Pa <![CDATA[≤5×10 0 ]]> <![CDATA[≤3×10 0 ]]> <![CDATA[≤3×10 0 ]]> Pre-melting leakage rate / Pa / min ≤0.9 ≤0.9 ≤0.9 Stable arc stirring reversal frequency / second / time 10 15 15 Maximum vacuum level during steady-state phase / Pa ≤35 ≤15 ≤15 Furnace cooling time / min ≥300 ≥360 ≥480

[0067] Sampling was performed on the R60702 ingot prepared in this embodiment at three points around its circumference: top, middle, and bottom. This included both block and shaving samples. The chemical composition was analyzed and determined according to AME SB-551 / SB-551M standards. The results are shown in Table 6 below.

[0068] Table 6

[0069]

[0070] As can be seen from Table 6, the mass content of O and other impurity elements in the R60702 ingot prepared in this embodiment meets the requirements of R60702 in the ASME SB-551 / 551M standard, and the O element is evenly distributed.

[0071] Comparing Example 1 and Example 2, it can be seen that Example 2 uses about twice as much R60700 waste as Example 1, but its composition still meets the requirements of R60702 in ASME SB-551 / 551M standard, indicating that the preparation method of the present invention can realize the recycling of large quantities of R60700 waste.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for producing R60702 ingot by VAR melting using R60700 scrap, characterized in that, The method comprises the following steps: Step one, the block-shaped scrap materials generated in the production process of R60700 brand products including plate edges, rod heads, and risers are strictly classified and collected and stored, and then the classified and stored block-shaped scrap materials are sandblasted and pickled until the surface is free of contamination and silver-white; Step two, the PMI handheld spectrometer is used to detect the elements of the block-shaped scrap materials treated in step one, and other brand metal foreign matters are picked out to obtain R60700 scrap materials; Step three, according to the O mass content in the target product R60702 ingot, the required R60700 scrap materials, sponge zirconium, and ZrO2 are calculated; According to the standard AME SB-551 / SB-551M, the O mass content in R60702 is 0.10%~0.16%, the O mass content in the target product R60702 ingot is determined to be 0.125%, and the calculation formula is shown in formula (1): A= ×100%（1） wherein A is the O mass content in the target product R60702 ingot, w 1 is the O mass content in ZrO2, w 2 is the average O mass content in sponge zirconium, w 3 is the average O mass content in R60700 scrap, all in %, m 1 is the ZrO2 addition weight, m 2 is the sponge zirconium addition weight, m 3 is the R60700 scrap addition weight; Step four, according to the calculated proportion in step three, the powdery ZrO2 is added to the sponge zirconium for mixing, and the electrode block is pressed; Step five, the electrode block pressed in step four is spliced and welded in the center, then the outer side is wrapped with the plate-shaped R60700 scrap materials in the R60700 scrap materials in step two, and the waist-shaped R60700 scrap materials in the R60700 scrap materials are welded and tied to obtain the consumable electrode for VAR smelting; Step six, the consumable electrode obtained in step five is subjected to primary VAR smelting to obtain primary ingots, then two primary ingots are welded in the furnace, and secondary VAR smelting and tertiary VAR smelting are sequentially performed to obtain R60702 ingot.

2. A process for the production of R60702 ingot by VAR melting using R60700 scrap as claimed in claim 1, wherein, The R60702 ingot in step six is sampled at three points on the circumference, middle, and lower parts and subjected to chemical composition detection, and is determined according to the AME SB-551 / SB-551M standard.

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