Method for preparing Zr-3 cast ingot by using zirconium scrap-shaped residual material

Abstract

The invention discloses a method for preparing a Zr-3 cast ingot by using zirconium scrap-shaped residual materials. The method comprises the following steps: 1, collecting Zr-1 and Zr-3 scrap-shaped residual materials, and carrying out classified storage; 2, crushing to obtain flaky scraps; 3, sieving, magnetic separation and manual separation; 4, cleaning and airing to obtain zirconium scraps with pollution-free surfaces; 5, pressing the zirconium scraps into an electrode block, and welding to obtain a consumable electrode; and sixthly, the consumable electrode is smelted, and the finished Zr-3 cast ingot is obtained. According to the method, zirconium scrap-shaped residues of different marks generated in different machining processes are stored in a classified mode, matching is conducted according to different scrap-material oxygen content empirical values in different proportions, it is guaranteed that the oxygen content of Zr-3 cast ingots is controllable, the density and strength of consumable electrodes are guaranteed in combination with large-tonnage pressing, total recovery of the zirconium scrap-shaped residues is achieved, and the production cost is reduced. And the recycled Zr-3 cast ingot meeting the requirements of GB / T 26314-2010'zirconium and zirconium alloy grade and chemical composition 'is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous metal ingot recovery and smelting, and particularly relates to a method for preparing Zr-3 ingots by utilizing zirconium chip-like residues. Background Art

[0002] Zirconium grades Zr-1 and Zr-3, designated by the National Standard, correspond to grades R60700 and R60702, respectively, for general industrial use. Zirconium exhibits excellent corrosion resistance, exhibiting superior stability to various alkaline solutions compared to stainless steel and titanium, and boasts a hydrochloric acid corrosion resistance second only to tantalum and precious metals. Therefore, it is widely used in the manufacture of corrosion-resistant containers and equipment. Industrial production of zirconium primarily utilizes sponge zirconium and zirconium oxide powders via vacuum consumable arc melting. The use of scrap materials for remelting zirconium ingots is rare.

[0003] As the use of zirconium materials in industrial manufacturing increases, the amount of waste zirconium materials has also increased dramatically. Maximizing the utilization of these waste materials to reduce pressure on raw materials and the environment has become increasingly important. Currently, some companies are developing methods for recycling and remelting zirconium lump waste, or adding a small amount (generally no more than 15%) of waste chips to zirconium sponge for smelting. However, there is no industrial production example of 100% recycling and remelting of zirconium waste chips. The main difficulties are as follows:

[0004] (1) Traditional titanium chips are mainly recycled in EB furnaces. However, when zirconium chips are melted in EB furnaces, the electron beam will be deflected, so EB furnace melting is not suitable.

[0005] (2) Zirconium chips react violently in acid or alkali solutions, and because zirconium is highly flammable, it poses a safety hazard. Therefore, conventional acid and alkali washing methods cannot be used to treat the chips.

[0006] (3) Since the chips come from the surface of the billet, and the turning process is also prone to oxidation, and the degree of oxidation is difficult to judge, the oxygen content of the recovered ingot is difficult to control;

[0007] The electrode blocks pressed from pure chips have low density, and the consumable electrodes are not firm after welding. They are prone to falling off during smelting, and there is a risk of "egg falling" in severe cases. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to address the shortcomings of the above-mentioned prior art and provide a method for producing Zr-3 ingots using zirconium chip residues. This method classifies and stores zirconium chips generated by different grades and different processing processes, standardizes the processing steps before smelting the zirconium chip residues, and combines them with welding using a large-tonnage hydraulic press to facilitate chip proportioning, ensure controllable oxygen content in the Zr-3 ingot, and guarantee the density and strength of the consumable electrode. This method then produces and recycles Zr-3 ingots that meet service requirements through VAR smelting, resolving the difficulty of 100% recycling and remelting zirconium chips.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing Zr-3 ingots using zirconium chip-like residues, characterized in that the method comprises the following steps:

[0010] Step 1: Collect, classify and store the scraps generated during the production of Zr-1 and Zr-3;

[0011] Step 2: crushing the scraps classified and stored in step 1 by a crusher, so that the original agglomerated scraps are converted into flaky scraps;

[0012] Step 3: The flaky chips obtained in step 2 are screened and magnetically separated to remove foreign matter introduced during the processing, and the chips with severe oxidation such as blue or yellowing on the surface are manually sorted to remove them;

[0013] Step 4: Clean the flaky chips after screening, magnetic separation and manual sorting in step 3 with a metal cleaning agent to remove surface oil and foreign matter, and then air-dry them to obtain surface-uncontaminated zirconium chips;

[0014] Step 5: Press the zirconium chips obtained in step 4 into electrode blocks through a 5000T to 8000T hydraulic press, and weld the electrode blocks to obtain consumable electrodes required for VAR smelting;

[0015] Step 6: The consumable electrode obtained in step 5 is subjected to three VAR smelting processes to obtain a finished Zr-3 ingot, and samples are taken from the upper, middle and lower circumferences of the Zr-3 ingot for chemical composition testing.

[0016] Unlike the process in the prior art in which the shavings from titanium ingots are pre-treated by cleaning, screening, etc., and then pressed into electrode blocks for welding and smelting to prepare recycled ingots, the shavings generated during the production of the raw materials of the present invention, namely Zr-1 and Zr-3, not only have different metallic properties from the shavings from titanium ingots, but also have the characteristics of high hardness, high brittleness, and poor toughness. In particular, the forging shavings generated under high temperature (950°C to 1100°C) in the forging process of forging plates or forging bars are not only hard and brittle, but also have an extremely high oxygen content (oxygen mass content >0.3%), which easily causes the oxygen content in the recovered product to exceed the standard, so the recycling of zirconium shavings is extremely difficult. To this end, the present invention uses Zr-1 ingot peeling chips, Zr-1 forging chips, Zr-3 ingot peeling chips, and Zr-3 forging chips as raw materials according to the oxygen content in the target product Zr-3 ingot and mixes them uniformly in proportion. The type and mass ratio of the chips are adjusted to ensure that the composition of the mixed zirconium chips meets the oxygen element requirements of GB / T 26314-2010 "Zirconium and Zirconium Alloy Grades and Chemical Compositions". The chips are then pressed using a 5000T to 8000T hydraulic press to a density of up to 4.0g / cm 3 The electrode block generates high strength through high density, ensuring that the electrode block has a regular shape and does not slag, meeting the subsequent electrode block welding requirements.

[0017] The above-mentioned method for preparing Zr-3 ingots using zirconium chip-like residues is characterized in that in step 1, the chip-like residues generated in the production process of Zr-1 and Zr-3 are collected and stored in a classified manner according to Zr-1 ingot peeling chips, Zr-1 forging chips, Zr-3 ingot peeling chips, and Zr-3 forging chips, and isolation is ensured between different types of chip-like residues to prevent mixing.

[0018] The above-mentioned method for preparing Zr-3 ingots using zirconium chip-like residues is characterized in that the length of the flaky chips in step 2 is 50 mm to 100 mm.

[0019] The aforementioned method for preparing a Zr-3 ingot from zirconium chip residue is characterized in that the screening in step three uses an upper screen with an aperture of 80 mm to 100 mm and a lower screen with an aperture of 5 mm to 10 mm, and the magnetic separation uses a 0.1 T to 0.5 T strong magnet. By controlling the apertures of the upper and lower screens during screening, oversized or undersized flaky chips are removed, facilitating the subsequent electrode block pressing and smelting processes. The use of strong magnets removes magnetic foreign matter from the flaky chips, ensuring the purity of the Zr-3 ingot.

[0020] The above-mentioned method for preparing Zr-3 ingots using zirconium chip-like residues is characterized in that the cleaning agent in step 4 is prepared by mixing metal detergent: water = 5% to 10%: 90% to 95% by mass, and the metal cleaning agent is heated to 40°C to 60°C to clean the flaky chips for 20 minutes to 50 minutes, and then rinsed with clean water until the surface is silvery white and free of oil stains, and then dried in a dry, clean, foreign matter-free environment for 10 hours to 48 hours.

[0021] The above-mentioned method for preparing Zr-3 ingots using zirconium chip residues is characterized in that in step 5, zirconium chips are selected according to the oxygen content in the target product Zr-3 ingot and mixed and then pressed into electrode blocks, and the electrode block density is 3.6g / cm 3 ~4.2g / cm 3 Then, the electrode blocks are welded together using argon-shielded plasma welding. The diameter of the weld point is not less than 30 mm, and Zr-3 strips are used for reinforcement welding after welding.

[0022] The above-mentioned method for preparing Zr-3 ingots using zirconium chip-like residues is characterized in that the process parameters of the three VAR smeltings in step 6 are as follows: the current of the first smelting is 8.0kA~21.0kA, the voltage is 26.0V~36.0V, and the vacuum degree does not exceed 35Pa, and the ingot with an ingot diameter of Φ400mm~620mm is obtained; the current of the second smelting is 10.0kA~31.0kA, the voltage is 28.0V~38.0V, and the vacuum degree is not more than 35Pa. The pressure exceeds 20Pa, and a secondary ingot with an ingot diameter of Φ480mm to 720mm is obtained; the current of the tertiary smelting is 15.0kA to 33.0kA, the voltage is 28.0V to 40.0V, and the vacuum degree does not exceed 5Pa, and a tertiary ingot with an ingot diameter of Φ540mm to 820mm, namely, a finished Zr-3 ingot, is obtained; the chemical composition of the finished Zr-3 ingot meets the Zr-3 grade requirements in GB / T26314-2010 "Zirconium and Zirconium Alloy Grades and Chemical Compositions".

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The present invention classifies and stores zirconium chip residues of different brands and produced during different processing processes, so that different proportions of the chips can be mixed according to the empirical values of oxygen content when preparing electrode blocks, thereby ensuring that the oxygen content of the recycled remelted Zr-3 ingot is controllable, thereby achieving full recovery of the zirconium chip residues.

[0025] 2. The present invention ensures the density of the pressed electrode blocks by using a large-tonnage hydraulic press. Combined with limiting the size of the weld spots and using auxiliary strips for reinforced welding, the density and strength of the consumable electrode are further ensured, avoiding block dropout during smelting. Thus, after three vacuum consumable arc melting (VAR melting) processes, a recycled Zr-3 ingot that meets the requirements of GB / T 26314-2010 "Zirconium and Zirconium Alloy Grades and Chemical Compositions" is obtained.

[0026] 3. The present invention standardizes the processing steps of zirconium chip residues before smelting, including crushing, screening, cleaning, and airing, thereby ensuring that the treated zirconium chips are clean and free of foreign matter, and avoiding the safety hazards of acid and alkali washing of the chips.

[0027] The technical solution of the present invention is further described in detail below through examples. DETAILED DESCRIPTION

[0028] Example 1

[0029] This embodiment includes the following steps:

[0030] Step 1: Collect and classify the scraps generated during the production of Zr-1 and Zr-3 into Zr-1 ingot peeling scraps, Zr-1 forging scraps, Zr-3 ingot peeling scraps, and Zr-3 forging scraps, and separate the different types of scraps to prevent mixing.

[0031] Step 2: crushing the scraps classified and stored in step 1 by a crusher, so that the original agglomerated scraps are converted into flakes; the length of the flakes is 50 mm to 80 mm;

[0032] Step 3: The flaky chips obtained in step 2 are screened and magnetically separated, wherein the upper screen aperture used for screening is 80 mm and the lower screen aperture is Φ5 mm. The magnetic separation uses a strong magnetic magnet of 0.1T to 0.5T to remove magnetic foreign matter introduced during the processing, and manually sorting is performed to remove chips with severe oxidation such as blue or yellowing on the surface;

[0033] Step 4: The flaky chips after screening, magnetic separation and manual sorting in step 3 are cleaned with a metal cleaning agent. The cleaning agent is prepared by mixing metal detergent and water in a mass ratio of 10%:90%. The metal cleaning agent is heated to 40°C to clean the flaky chips for 50 minutes to remove surface oil and foreign matter. The flaky chips are then rinsed with clean water until the surface is silvery white and free of oil. The flaky chips are then aired in a dry, clean environment free of foreign matter for 10 hours to obtain surface-uncontaminated zirconium chips.

[0034] Step 5: According to the oxygen content of the target product Zr-3 ingot, the zirconium chips obtained in step 4 were mixed evenly in a mass ratio of Zr-1 ingot peeling chips: Zr-3 forging chips = 4:1, and pressed into electrode blocks using a 5000T hydraulic press. The electrode block density was 3.6g / cm 3 Then, the electrode blocks are welded together using argon-shielded plasma welding, with a weld spot diameter of 30 mm to 40 mm. After welding, Zr-3 strips are used for reinforcement welding to obtain the consumable electrodes required for VAR smelting.

[0035] Step 6: The consumable electrode obtained in step 5 was subjected to three VAR smelting processes with the process parameters shown in Table 1 below to obtain a finished Zr-3 ingot. Samples were taken from the upper, middle, and lower circumferences of the Zr-3 ingot for chemical composition testing. The test results are shown in Table 2 below.

[0036] Table 1

[0037] Process Ingot shape / mm Current / kA Voltage / V Vacuum degree / Pa One smelting Φ400 8.0～12.0 26.0～34.0 ≤35 Secondary smelting Φ480 10.0～16.0 28.0～34.0 ≤20 Three smelting Φ540 15.0～22.0 28.0～36.0 ≤5

[0038] Table 2

[0039]

[0040] As can be seen from Table 2, the contents of O and other impurity elements in the finished Zr-3 ingot prepared in this embodiment meet the Zr-3 grade requirements in GB / T26314-2010 "Zirconium and Zirconium Alloy Grades and Chemical Compositions", and the O element is evenly distributed.

[0041] Example 2

[0042] This embodiment includes the following steps:

[0043] Step 1: Collect and classify the scraps generated during the production of Zr-1 and Zr-3 into Zr-1 ingot peeling scraps, Zr-1 forging scraps, Zr-3 ingot peeling scraps, and Zr-3 forging scraps, and separate the different types of scraps to prevent mixing.

[0044] Step 2: crushing the scraps classified and stored in step 1 by a crusher, so that the original agglomerated scraps are converted into flakes; the length of the flakes is 80 mm to 100 mm;

[0045] Step 3: The flaky chips obtained in step 2 are screened and magnetically separated, wherein the upper screen aperture used for screening is 100 mm and the lower screen aperture is 10 mm. The magnetic separation uses a strong magnetic magnet of 0.1T to 0.5T to remove magnetic foreign matter introduced during the processing, and manually sorting is performed to remove chips with severe oxidation such as blue or yellowing on the surface;

[0046] Step 4: The flaky chips after screening, magnetic separation and manual sorting in step 3 are cleaned with a metal cleaning agent. The cleaning agent is prepared by mixing metal detergent and water in a ratio of 5%:95%. The metal cleaning agent is heated to 60°C to clean the flaky chips for 20 minutes to remove surface oil and foreign matter. The flaky chips are then rinsed with clean water until the surface is silvery white and free of oil. The flaky chips are then aired in a dry, clean environment free of foreign matter for 10 hours to obtain surface-free zirconium chips.

[0047] Step 5: According to the oxygen content of the target product Zr-3 ingot, the zirconium chips obtained in step 4 are mixed uniformly according to the mass ratio of Zr-1 ingot peeling chips: Zr-3 forging chips: Zr-3 forging chips = 1:1:1, and pressed into electrode blocks using an 8000T hydraulic press, and the electrode block density is 4.2g / cm 3 Then, the electrode blocks are welded together using argon-shielded plasma welding, with a weld spot diameter of 30 mm to 40 mm. After welding, Zr-3 strips are used for reinforcement welding to obtain the consumable electrodes required for VAR smelting.

[0048] Step 6: The consumable electrode obtained in step 5 was subjected to three VAR smelting processes with the process parameters shown in Table 3 below to obtain a finished Zr-3 ingot. Samples were taken from the upper, middle, and lower circumferences of the Zr-3 ingot for chemical composition testing. The test results are shown in Table 4 below.

[0049] Table 3

[0050] Process Ingot shape / mm Current / kA Voltage / V Vacuum degree / Pa One smelting Φ560 12.0～21.0 28.0～36.0 ≤35 Secondary smelting Φ640 16.0～26.0 30.0～36.0 ≤20 Three smelting Φ720 20.0～29.0 31.0～38.0 ≤5

[0051] Table 4

[0052]

[0053]

[0054] As can be seen from Table 4, the contents of O and other impurity elements in the finished Zr-3 ingot prepared in this embodiment meet the Zr-3 grade requirements in GB / T26314-2010 "Zirconium and Zirconium Alloy Grades and Chemical Compositions", and the O element is evenly distributed.

[0055] Example 3

[0056] This embodiment includes the following steps:

[0057] Step 1: Collect and classify the scraps generated during the production of Zr-1 and Zr-3 into Zr-1 ingot peeling scraps, Zr-1 forging scraps, Zr-3 ingot peeling scraps, and Zr-3 forging scraps, and separate the different types of scraps to prevent mixing.

[0058] Step 2: crushing the scraps classified and stored in step 1 by a crusher, so that the original agglomerated scraps are converted into flakes; the length of the flakes is 60 mm to 85 mm;

[0059] Step 3: The flaky chips obtained in step 2 are screened and magnetically separated, wherein the upper screen aperture used for screening is 90 mm and the lower screen aperture is 8 mm. The magnetic separation uses a strong magnetic magnet of 0.1T to 0.5T to remove magnetic foreign matter introduced during the processing, and manually sorting is performed to remove chips with severe oxidation such as blue or yellowing on the surface;

[0060] Step 4: The flaky chips after screening, magnetic separation and manual sorting in step 3 are cleaned with a metal cleaning agent. The cleaning agent is prepared by mixing metal detergent and water in a ratio of 8%:92%. The metal cleaning agent is heated to 50°C to clean the flaky chips for 35 minutes to remove surface oil and foreign matter. The flaky chips are then rinsed with clean water until the surface is silvery white and free of oil. The flaky chips are then aired in a dry, clean environment free of foreign matter for 48 hours to obtain surface-free zirconium chips.

[0061] Step 5: According to the oxygen content of the target product Zr-3 ingot, the zirconium chips obtained in step 4 were mixed evenly in a mass ratio of Zr-1 ingot peeling chips: Zr-1 forging chips: Zr-3 forging chips = 4:3:1, and pressed into electrode blocks using an 8000T hydraulic press. The electrode block density was 4.0g / cm 3 Then, the electrode blocks are welded together using argon-shielded plasma welding, with a weld spot diameter of 30 mm to 45 mm. After welding, Zr-3 strips are used for reinforcement welding to obtain the consumable electrodes required for VAR smelting.

[0062] Step 6: The consumable electrode obtained in step 5 was subjected to three VAR smelting processes with the process parameters shown in Table 5 below to obtain a finished Zr-3 ingot. Samples were taken from the upper, middle, and lower circumferences of the Zr-3 ingot for chemical composition testing. The test results are shown in Table 6 below.

[0063] Table 5

[0064] Process Ingot shape / mm Current / kA Voltage / V Vacuum degree / Pa One smelting Φ640 16.0～26.0 28.0～36.0 ≤35 Secondary smelting Φ720 20.0～31.0 30.0～38.0 ≤20 Three smelting Φ820 25.0～33.0 32.0～40.0 ≤5

[0065] Table 6

[0066]

[0067] As can be seen from Table 6, the contents of O and other impurity elements in the finished Zr-3 ingot prepared in this embodiment meet the Zr-3 grade requirements in GB / T26314-2010 "Zirconium and Zirconium Alloy Grades and Chemical Compositions", and the O element is evenly distributed.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing Zr-3 ingots using zirconium chip residues, characterized in that: The method comprises the following steps: Step 1: Collect, classify and store the scraps generated during the production of Zr-1 and Zr-3; Step 2: crushing the scraps classified and stored in step 1 by a crusher, so that the original agglomerated scraps are converted into flaky scraps; Step 3: The flaky chips obtained in step 2 are screened and magnetically separated to remove foreign matter introduced during the processing, and the chips with severe oxidation such as blue or yellowing on the surface are manually sorted to remove them; Step 4: Clean the flaky chips after screening, magnetic separation and manual sorting in step 3 with a metal cleaning agent to remove surface oil and foreign matter, and then air-dry them to obtain surface-uncontaminated zirconium chips; Step 5: Press the zirconium chips obtained in step 4 into electrode blocks through a 5000T to 8000T hydraulic press, and weld the electrode blocks to obtain consumable electrodes required for VAR smelting; Step 6: The consumable electrode obtained in step 5 is subjected to three VAR smelting processes to obtain a finished Zr-3 ingot, and samples are taken from the upper, middle and lower circumferences of the Zr-3 ingot for chemical composition testing.

2. The method for preparing Zr-3 ingots using zirconium chip residues according to claim 1, characterized in that: In step 1, the chip residues generated during the production of Zr-1 and Zr-3 are collected and stored in the form of Zr-1 ingot peeling chips, Zr-1 forging chips, Zr-3 ingot peeling chips, and Zr-3 forging chips, and the different types of chip residues are isolated to prevent mixing.

3. The method for preparing Zr-3 ingots using zirconium chip residues according to claim 1, characterized in that: The length of the flaky scraps in step 2 is 50 mm to 100 mm.

4. The method for preparing Zr-3 ingots using zirconium chip residues according to claim 1, wherein: The pore size of the upper sieve used in the screening in step 3 is 80mm-100mm, and the pore size of the lower sieve is 5mm-10mm. The magnetic separation uses a strong magnetic magnet of 0.1T-0.5T.

5. The method for preparing Zr-3 ingots using zirconium chip residues according to claim 1, characterized in that: The cleaning agent in step 4 is prepared by mixing metal detergent and water in a mass ratio of 5% to 10% and 90% to 95%. The metal cleaning agent is heated to 40°C to 60°C to clean the flaky scraps for 20 to 50 minutes, then rinsed with clean water until the surface is silvery white and free of oil stains, and then aired in a dry, clean environment free of foreign matter for 10 to 48 hours.

6. The method for preparing Zr-3 ingots using zirconium chip residues according to claim 1, characterized in that: In step 5, zirconium chips are selected according to the oxygen content in the target product Zr-3 ingot and then pressed into electrode blocks with a density of 3.6 g / cm 3 ~4.2g / cm 3 Then, the electrode blocks are welded together using argon-shielded plasma welding. The diameter of the weld point is not less than 30 mm, and Zr-3 strips are used for reinforcement welding after welding.

7. The method for preparing Zr-3 ingots using zirconium chip residues according to claim 1, characterized in that: The process parameters of the three VAR smeltings in step 6 are as follows: the current of the first smelting is 8.0kA~21.0kA, the voltage is 26.0V~36.0V, and the vacuum degree does not exceed 35Pa, so as to obtain a primary ingot with an ingot diameter of Φ400mm~620mm; the current of the second smelting is 10.0kA~31.0kA, the voltage is 28.0V~38.0V, and the vacuum degree does not exceed 20Pa, so as to obtain a secondary ingot with an ingot diameter of Φ480mm~720mm; the current of the third smelting is 15.0kA~33.0kA, the voltage is 28.0V~40.0V, and the vacuum degree does not exceed 5Pa, so as to obtain a tertiary ingot with an ingot diameter of Φ540mm~820mm, i.e., the finished Zr-3 ingot; the chemical composition of the finished Zr-3 ingot meets the Zr-3 grade requirements in GB / T 26314-2010 "Zirconium and Zirconium Alloy Grades and Chemical Compositions".

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