A method for recycling waste zirconium-based amorphous alloy die castings

Abstract

The present invention relates to the technical field of die casting waste recycling methods, and in particular to a method for recycling zirconium-based amorphous alloy die casting waste, comprising the steps of pretreatment, shot blasting, crushing, magnetic separation, ultrasonic cleaning, drying, adding niobium oxide and yttrium elements to mix, vacuum suspension melting and the like. The application of the recycling method of the present invention can not only greatly reduce the carbon and oxygen content in the zirconium-based amorphous alloy recycled materials, but also avoid the alloy contamination caused by the burning of the crucible, so that the zirconium-based amorphous alloy waste reaches a purity that can be reused.

Description

Technical Field

[0001] The invention relates to the technical field of die casting waste recycling methods, and in particular to a zirconium-based amorphous alloy die casting waste recycling method. Background Art

[0002] Amorphous alloy, also known as liquid metal or metallic glass, refers to a substance that, when rapidly cooled from a liquid state, does not have time to crystallize and retains a condensed state of disordered arrangement of liquid atoms at room temperature or low temperature. Its atoms are no longer arranged in a long-range, periodic, and regular manner, but are in a disordered arrangement state. The internal atomic structure is extremely dense and has no weak links. Therefore, zirconium-based amorphous alloys are widely used in consumer electronics, sports equipment, smart wearables, medical devices, automobiles and other fields due to their special mechanical properties, such as extremely high strength, hardness, elasticity, and corrosion resistance, and have broad application prospects.

[0003] Suppressing the non-uniform nucleation of the melt is the core of the preparation of amorphous alloys. In order to prevent the formation of impurities inside the amorphous alloys and become potential non-uniform nucleation points and alloy oxides, the purity of the raw materials and the environmental atmosphere are very demanding. However, in the actual vacuum die-casting process, problems such as high leakage rate of the vacuum system of the die-casting machine and insufficient sealing of the mold will cause the introduction of oxygen elements, resulting in product performance that cannot meet customer needs and is scrapped. In addition, defective products will be produced during the product cutting, CNC machine adjustment, grinding and polishing, PVD, etc. of the die-casting parts, resulting in high production costs.

[0004] The existing recycling methods for zirconium-based amorphous alloy waste are mainly to reduce oxygen and inclusions in the zirconium-based amorphous alloy recycled materials through crushing, pickling, rust removal, oxide scale removal, alkali washing, water washing and drying, smelting with the addition of oxygen-affinity elements, blowing inert gas from the furnace bottom, and foam ceramic filtration, so as to achieve the purpose of recycling zirconium-based amorphous alloy waste.

[0005] Pickling is a traditional process for removing rust and oxide scale, but the main problems are: large acid mist, which causes corrosion of steel structures and equipment in the pickling workshop and surrounding plant buildings; large consumption of cleaning water; and pickling sediment polluting the environment. At the same time, the shrinkage cracks of refractory materials used in vacuum smelting are more serious than those in conventional smelting, because many refractory materials decompose according to components under vacuum conditions and react with molten metal, which not only causes damage to the refractory materials, but also pollutes the molten alloy. Summary of the invention

[0006] The technical problem to be solved by the present invention is: the present invention provides a method for recycling waste zirconium-based amorphous alloy die-castings, which can not only greatly reduce the oxygen content in the zirconium-based amorphous alloy, but also avoid the crucible from being corroded and contaminating the molten alloy during smelting, so that the zirconium-based amorphous alloy reaches a purity that can be reused.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A method for recycling waste zirconium-based amorphous alloy die castings comprises the following steps:

[0009] After pretreatment, the zirconium-based amorphous alloy die-casting waste is put into the shot blasting machine for shot blasting to remove the oxide scale and rust on the surface;

[0010] Crushing the die casting waste after shot blasting;

[0011] The crushed die casting waste is put into a magnetic separator for magnetic separation to separate the die casting waste from oxide scale and rust;

[0012] The die casting waste obtained by magnetic separation is ultrasonically cleaned and dried;

[0013] Adding niobium oxide and metal yttrium to the recycled material after washing and drying, mixing them evenly to obtain a mixed material;

[0014] The mixed material is put into a water-cooled copper crucible and subjected to suspension melting in an inert gas atmosphere;

[0015] After the molten melt is stabilized, it is poured into a mold and cooled in an inert gas atmosphere to form a mold.

[0016] Furthermore, in the above-mentioned zirconium-based amorphous alloy die-casting waste recycling method, the added amount of the metal yttrium is 0.25-0.5% of the mass of the zirconium-based amorphous alloy die-casting waste; the added amount of the niobium oxide is 0.2-0.3% of the mass of the zirconium-based amorphous alloy die-casting waste.

[0017] Furthermore, in the above-mentioned method for recycling waste zirconium-based amorphous alloy die-castings, the mass ratio of metal yttrium to niobium oxide in the mixture is 5:4.

[0018] Furthermore, in the above-mentioned zirconium-based amorphous alloy die-casting waste recycling method, the mass parts of the zirconium-based amorphous alloy die-casting waste are 20,000 parts, the mass parts of the metal yttrium are 40 parts, and the mass parts of the niobium oxide are 50 parts.

[0019] Furthermore, in the above-mentioned zirconium-based amorphous alloy die-casting waste recycling method, in the shot blasting process, the shot blasting medium is selected from stainless steel shots, ceramic beads or glass sand, the particle size of the shot blasting medium is 60-100 mesh, and the shot blasting time is 3-7 minutes.

[0020] Furthermore, in the above-mentioned method for recycling waste zirconium-based amorphous alloy die-castings, the magnetic field strength of the magnetic separation is 8000-12000 Gs.

[0021] Furthermore, in the above-mentioned method for recycling waste zirconium-based amorphous alloy die-castings, the inert gas in the water-cooled copper crucible is selected from one of argon, helium and neon.

[0022] Furthermore, in the above-mentioned zirconium-based amorphous alloy die-casting waste recycling method, the step of putting the mixed material into a water-cooled copper crucible and performing suspension smelting in an inert gas atmosphere is specifically as follows: putting the mixed material into a water-cooled copper crucible, evacuating the water-cooled copper crucible to below 0.5 Pa, filling it with inert gas, the smelting temperature is 220-350°C, and the smelting time is 10-30min.

[0023] Furthermore, in the above-mentioned method for recycling waste zirconium-based amorphous alloy die-casting parts, the pretreatment includes removing nuts from the waste zirconium-based amorphous alloy die-casting parts, removing glue and stripping the plating layer.

[0024] The beneficial effects of the present invention are as follows: the method for recycling zirconium-based amorphous alloy die-casting waste involved in the present invention includes the steps of pretreatment, shot blasting, crushing, magnetic separation, ultrasonic cleaning, drying, adding niobium oxide and yttrium elements to mix, vacuum suspension melting, etc. The application of the recycling method in the present invention can not only greatly reduce the carbon and oxygen content in the zirconium-based amorphous alloy recycled materials, but also avoid the contaminated alloy caused by the burning of the crucible, so that the zirconium-based amorphous alloy waste reaches a purity that can be reused. DETAILED DESCRIPTION

[0025] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes.

[0026] The present invention relates to a method for recovering a zirconium-based amorphous alloy, comprising the following steps:

[0027] (1) Pretreatment of recycled materials, including smelting process waste, die-casting waste, CNC waste, die-casting product cutting waste, grinding and polishing waste, PVD waste, and rubber-coated waste. Among the waste generated by grinding and polishing, the implanted nuts need to be removed first; the rubber-coated waste needs to be soaked in glue removal water, de-glueed and cleaned; the injection molding waste is hot-melted and then separated from the plastic with tools; PVD waste is uniformly stripped with sodium hydroxide to remove the surface coating of the product.

[0028] (2) Zirconium, the main element in zirconium-based amorphous alloys, easily reacts with oxygen to form oxides on the surface of the alloy. Since most of the recycled materials have not undergone subsequent processing, the surface is relatively rough. At the same time, due to the storage time, surface oxidation and rust often occur. The pre-treated zirconium-based amorphous alloy is shot blasted with a shot blasting machine. The centrifugal force of the shot blasting machine is used to project the surface zirconium-based amorphous alloy at high speed, especially the dead corners of the inner cavity of the defective products after crushing, so as to achieve the effect of rust and scale removal. Compared with steel shots and iron sand, ceramic beads have no iron elements and dust pollution to the recycled materials.

[0029] (3) After processing, the jaw crusher crushes the zirconium-based amorphous alloy recycling material into a size of 3-10 mm.

[0030] (4) The recycled materials after shot blasting and descaling contain fine oxides, rust, etc., which are magnetically separated and screened by a dry magnetic separator through its high gradient magnetic field.

[0031] (5) Ultrasonic cleaning is performed on the zirconium-based amorphous alloy recycled materials after magnetic separation and screening. The cavitation, acceleration and straight-forward flow of sound waves in the liquid directly and indirectly affect the dirt and grease on the liquid and recycled materials, so that the dirt layer is dispersed, emulsified and peeled off to achieve the purpose of decontamination and oil removal. The cleaning agent uses a solution with a low alkalinity for surface degreasing and cleaning. Too strong alkalinity will cause uneven erosion on the surface of the recycled materials. Alkaline degreasing and degreasing solutions generally meet the following requirements:

[0032] 1.PH value 9-11.

[0033] 2. It has stable performance and high emulsification ability, and can effectively dissolve and disperse oil and fat and form soluble saponification with it.

[0034] 3. It has the ability to disperse and condense, and can rely on the colloidal effect to disperse pollutant particles such as dust into the solution.

[0035] (6) The water used in ultrasonic cleaning can be tap water, deionized water, or distilled water.

[0036] (7) During the die-casting process of zirconium-based amorphous alloys, if the oxygen content in the melt is high, it will lead to low forming ability and increased brittleness of the resulting amorphous alloy structure. At the same time, alloy melts with high oxygen content are prone to form stable endogenous oxide inclusions. The presence of inclusions not only affects the macroscopic quality of die-cast products, such as appearance and strength, but also often becomes a heterogeneous core during the molding process, leading to the occurrence of crystallization, thereby affecting the formation of amorphous alloys. Therefore, an appropriate amount of metal yttrium and impurity remover niobium oxide are added to the recycled material after cleaning and drying according to the weight of the recycled material and put into the suspension melting furnace for melting.

[0037] (8) Currently, oxide ceramic crucibles are mostly used for the smelting of amorphous alloys. Since zirconium-based amorphous alloy melts are highly active at high temperatures, they are easy to corrode the crucible, causing some oxide ceramic particles that make up the crucible to enter the alloy melt. This method uses a water-cooled copper crucible for suspension smelting, which avoids direct contact between the melt and the crucible, and there are no impurities from the crucible. At the same time, the water-cooled copper crucible induction suspension smelting has a strong electromagnetic stirring effect, which can generate an alloy with uniform composition and structure. At the same time, any shape of amorphous recycled materials can be smelted, such as blocks, powders, flakes, chips, sponges, etc.

[0038] (9) Melting conditions: vacuum degree below 0.5 Pa, filled with inert protective gas, melting temperature 250-350°C above the melting point of the amorphous alloy.

[0039] (10) During the smelting process, as the temperature rises, niobium oxide reacts with impurity carbon continuously, and finally Nb and CO are reduced to achieve the effect of removing impurity carbon. The reaction formula is as follows:

[0040] Nb 2 O 5 +C=2NbO 2 +CO

[0041] 2NbO 2 +C=NbO+CO

[0042] NbO+C=Nb+CO

[0043] (11) The casting temperature can be 100-120°C lower than the melting temperature.

[0044] (12) The recycled material melt is poured from the furnace under vacuum or inert atmosphere and poured into a designed mold for cooling and molding.

[0045] Example 1

[0046] A method for recovering zirconium-based amorphous alloy comprises the following steps:

[0047] Step 1: Pre-treated Zr 70 Cu 12.5 Al 3.3 Ni 10 Nb 4 Y 0.2 (Oxygen content 800ppm, carbon content 800ppm, silicon content 2000ppm) Zirconium-based amorphous alloy die-casting material handle recovery material 20kg, shot blasting to remove rust, using 60 mesh zirconium oxide sand shot blasting time 5min;

[0048] Step 2: Crushing the surface treated recycled materials to a size of 3-7mm;

[0049] Step 3: Use ERIEZ dry vibration filter DVMF magnetic separator to separate the rust in the recycled material, with a magnetic field induction intensity of 10000Gs;

[0050] Step 4: After separating the rust, the recycled material is ultrasonically cleaned, then washed with water until there is no residue on the surface of the recycled material, and then dried. The formula of the alkaline melt in the cleaning solution is Na 2 CO 3 20g / L, NaHCO 3 35g / L, C 12 H 25 SO 4 A small amount of Na. The temperature can be between 35-45℃, and the ultrasonic cleaning time is 3min;

[0051] Step 5: Add 50g of metal yttrium and 40g of niobium oxide to the recycled material treated in step 4 and smelt them in an argon atmosphere. When the vacuum degree of the furnace body reaches the vacuum degree required by the process through a mechanical pump, a booster pump, and a Roots pump, close the main pumping valve and the rough pumping valve, open the argon valve and fill the furnace body with argon. Smelting can only be carried out when the digital vacuum degree (0.08) of the argon filling instrument is less than 20000Pa;

[0052] Step 6: Power the induction coil to make the power reach the smelting power, and the smelting temperature is controlled at 1200 degrees (250 degrees above the melting point);

[0053] Step 7: During the smelting process, pay attention to the inlet and outlet temperatures of the crucible cooling water. Set the alarm temperature of the crucible cooling water outlet temperature to 50°C, and the maximum cooling water temperature should not exceed 65°C (to prevent the cooling water in the high-temperature crucible from vaporizing and the crucible from melting through).

[0054] Step 8: After the melt temperature reaches 1000℃, slowly lower the temperature to 1000℃, then pour the melt into the designed mold. After cooling to the temperature required by the process, manually open the vent valve. After that, close the vent valve to obtain the amorphous alloy sheet.

[0055] Example 2

[0056] The treatment was carried out according to the method of Example 1, except that the selected recycled material was Zr 66.7 Cu 14 Al 4.8 Ni 10 Nb 2.2 Y 0.4 Ti 1.9 (Oxygen content 800ppm, carbon content 800ppm, silicon content 2000ppm) 20kg of recycled zirconium-based amorphous alloy die-casting handle.

[0057] The medium used for shot blasting is 80 mesh stainless steel shot, and the magnetic field induction intensity of ERIEZ dry vibrating filter DVMF magnetic separator is 12000Gs.

[0058] Example 3

[0059] The treatment was carried out according to the method of Example 1, except that the selected recycled material was Zr 50.9 Cu 42.3 Nb 2.8 Y 0.2 Ti 3.8 (Oxygen content 1000ppm, carbon content 800ppm, silicon content 2000ppm) 20kg of recycled zirconium-based amorphous alloy die-casting handle.

[0060] The medium used for shot blasting is 80 mesh glass sand.

[0061] Comparative Example 1

[0062] This comparative example is used to illustrate a method for recycling waste zirconium-based amorphous alloy die castings disclosed in the present invention.

[0063] Zr 70 Cu 12.5 Al 3.3 Ni 10 Nb 4 Y 0.2 (Oxygen content 1000ppm, carbon content 800ppm, silicon content 2000ppm) 20kg of recycled zirconium-based amorphous alloy die-casting handle.

[0064] After the shot blasting, crushing, magnetic separation, cleaning and drying of Example 1.

[0065] 50 g of yttrium, an oxygen-affinity element, was added to the treated recycled material, and conventional vacuum induction melting was performed in an argon protective atmosphere, and an amorphous alloy sheet was obtained by casting.

[0066] Ingredient testing

[0067] The carbon content, oxygen content and silicon content were tested using the CS995 carbon and sulfur analyzer of Wuxi Jiebo Instrument Technology Co., Ltd., the ON-3000 oxygen and nitrogen analyzer of Beijing Gangyan Nak Testing Technology Co., Ltd., and the ICP-MS 2000 of Jiangsu Tianrui Instrument Co., Ltd. The test results are shown in Table 1 below.

[0068] Table 1

[0069] sample Oxygen content / ppm Carbon content / ppm Silicon content / ppm Example 1 385 494 2520 Example 2 410 516 2480 Example 3 390 508 2579 Comparative Example 1 440 928 3280

[0070] From the test results of the above three embodiments and one comparative example, it can be seen that the method disclosed in the present invention can effectively reduce the oxygen and carbon contents in the amorphous alloy waste without introducing impurity elements other than the component components, and reduce the pollution of the crucible to the alloy during vacuum melting. The oxygen content and carbon content after treatment are both lower than 600ppm, which meets the basic requirements of amorphous alloy production.

[0071] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for recycling waste zirconium-based amorphous alloy die castings, It is characterized in that The following steps are involved: After pretreatment, the zirconium-based amorphous alloy die-casting waste is put into the shot blasting machine for shot blasting to remove the oxide scale and rust on the surface; Crushing the die casting waste after shot blasting; The crushed die casting waste is put into a magnetic separator for magnetic separation to separate the die casting waste from oxide scale and rust; The die casting waste obtained by magnetic separation is ultrasonically cleaned and dried; Adding niobium oxide and metal yttrium to the recycled material after washing and drying, mixing them evenly to obtain a mixed material; The mixed material is put into a water-cooled copper crucible and subjected to suspension melting in an inert gas atmosphere; After the molten melt is stabilized, it is poured into a mold and cooled in an inert gas atmosphere to form a mold.

2. The method for recycling waste zirconium-based amorphous alloy die castings according to claim 1, It is characterized in that The added amount of the metal yttrium is 0.25-0.5% of the mass of the zirconium-based amorphous alloy die-casting waste; the added amount of the niobium oxide is 0.2-0.3% of the mass of the zirconium-based amorphous alloy die-casting waste.

3. The method for recycling waste zirconium-based amorphous alloy die castings according to claim 1, It is characterized in that In the mixture, the mass ratio of metal yttrium to niobium oxide is 5:

4.

4. The method for recycling waste zirconium-based amorphous alloy die castings according to claim 1, It is characterized in that The mass parts of the zirconium-based amorphous alloy die-casting waste are 20,000 parts, the mass parts of the metal yttrium are 40 parts, and the mass parts of the niobium oxide are 50 parts.

5. The method for recycling waste zirconium-based amorphous alloy die castings according to claim 1, It is characterized in that In the shot blasting process, the shot blasting medium is selected from stainless steel shots, ceramic beads or glass sand, the particle size of the shot blasting medium is 60-100 meshes, and the shot blasting time is 3-7 minutes.

6. The method for recycling waste zirconium-based amorphous alloy die castings according to claim 1, It is characterized in that The magnetic field strength of the magnetic separation is 8000-12000Gs.

7. The method for recycling waste zirconium-based amorphous alloy die castings according to claim 1, It is characterized in that The inert gas in the water-cooled copper crucible is selected from one of argon, helium and neon.

8. The method for recycling waste zirconium-based amorphous alloy die castings according to claim 1, It is characterized in that The step of putting the mixed material into a water-cooled copper crucible and performing suspension smelting in an inert gas atmosphere is specifically as follows: putting the mixed material into a water-cooled copper crucible, evacuating the water-cooled copper crucible to below 0.5 Pa, filling it with inert gas, the smelting temperature is 220-350° C. above the melting point of the alloy, and the smelting time is 10-30 min.

9. The method for recycling waste zirconium-based amorphous alloy die castings according to claim 1, It is characterized in that The pretreatment includes taking out nuts from waste zirconium-based amorphous alloy die castings, removing glue and stripping the plating layer.