A smelting method for recycling waste copper alloy

Abstract

The present invention provides a smelting method for recycling waste copper alloy, comprising the following steps: (a) sorting; (b) selecting; (c) sandblasting; (d) splitting; (e) primary cleaning; (f) secondary cleaning; (g) drying: drying the waste copper alloy mold; and further comprising the following steps: (h) primary smelting: placing the waste copper alloy mold in a medium frequency electric furnace, smelting to 1200-1250°C, adding a 3-5 cm thick covering agent to the surface of the molten copper, and blowing in an inert gas for purification; (i) secondary smelting: detecting the composition of the molten copper ingot, adding new material according to the copper alloy composition range, and adding the trace element Ti, smelting to 1230-1280°C, adding a portion of flux, and removing scum; heating to 1280-1320°C, and casting to obtain a finished copper alloy mold. By coordinating the various process steps, especially the primary smelting and secondary smelting, the molten copper remains pure.

Description

Technical Field

[0001] The invention belongs to the technical field of glass mold material recycling and relates to a smelting method, in particular to a smelting method for recycling waste copper alloy. Background Art

[0002] Copper and copper alloys are metals that can be found everywhere in daily life and were developed and used by humans early on.

[0003] Due to its advantages such as high conductivity, ductility, corrosion resistance and thermal conductivity, copper is widely used in electrical and electronic fields (power transmission requires conductors and carriers, and copper has good conductivity and can be used as a conductor, contact, etc. in cables, switches and other fields), construction (copper and copper alloys have good corrosion resistance to various solutions and are used to manufacture various containers, pipes and other devices), machinery and metallurgy (in the machinery industry, it is used to manufacture various gears, nuts, bolts, etc.; in the metallurgical industry, various induction coils of electric arc furnaces or electric slag furnaces are made of copper tubes, or it is used as an important element to form metal alloys in the smelting of non-ferrous metals) and other industries.

[0004] While a wide variety of mold materials are available in the glass mold (i.e., glass forming mold) industry, copper alloys offer the best combination of antioxidant, fatigue resistance, and corrosion resistance. The most popular alloy is the aluminum-nickel-zinc-copper alloy. Copper production, from mining to production, requires multiple steps. Furthermore, domestic copper resources are scarce, and copper ore is a non-renewable resource, making copper recycling extremely urgent.

[0005] The recycling of copper alloy molds is a technological direction that effectively utilizes valuable resources and promotes sustainable development. Recycling scrap copper alloy molds is both energy-efficient and economical, saving 60-70% of raw materials compared to directly using electrolytic copper, thus possessing extremely high economic value. In the actual production process of mold manufacturers, many factors influence the use of recycled copper alloy molds: technical limitations, product development and design, and the manufacturer's level of attention. Research on the recycling of copper alloy glass molds is scarce in published patent literature. The core steps of copper alloy glass mold recycling are the rational design of the proportion of scrap copper alloy materials, recycling, and smelting. For example, during the smelting process, gas absorption and oxidation are prone to occur. Existing methods typically increase the number of smelting cycles, which inevitably introduces oxidizing components. Furthermore, the mold contains various holes and cavities, which can harbor oxides such as glass impurities that are difficult to remove. During the smelting process, these oxides dissolve in the copper liquid, oxidizing it and producing products such as cupric oxide and cuprous oxide. As the cuprous oxide and cupric oxide at the bottom rise, slag pores form, damaging the mold's mechanical properties. Furthermore, some relatively active trace elements, such as silicon and manganese, react with moisture in the furnace gas to displace hydrogen atoms. These atoms exist as dispersed bubbles in the copper liquid, unable to escape and, upon solidification, form pores in the mold. In summary, how to utilize recycled copper alloy molds for remelting and ensure product quality is a technical challenge in mold recycling.

[0006] Chinese invention patent application number 202210931578.3 discloses a vacuum melting process for purifying low-silver, low-sulfur, ultra-high-purity copper. The process specifically includes the following steps: S1. Treatment of scrap copper: Pre-removing surface rust from the scrap copper and cleaning it. The pre-treated scrap copper is then fed into a crusher, which crushes it to a diameter of ≤150mm. A screening machine is used to screen the crushed material. The under-screened material is kept ready for use, while the over-screened material is returned to the crusher for crushing until it passes the screening. S2. Material heat treatment: The material screened in step S1 is placed in a roaster for heat treatment. This low-silver, low-sulfur, ultra-high-purity copper requires the use of electrolytic nickel and vacuum melting process conditions, which is costly and demanding. Summary of the Invention

[0007] In order to solve the above technical problems, the object of the present invention is to provide a smelting method for recycling waste copper alloy.

[0008] In order to solve the above technical problems, the present invention provides a smelting method for recycling waste copper alloy, comprising the following steps:

[0009] (a) Sorting: sorting various molds and selecting scrap copper alloy molds;

[0010] (b) selection: performing composition testing on the waste copper alloy molds to select waste copper alloy molds having a composition close to or within a desired copper alloy composition range;

[0011] (c) Sandblasting: Sandblasting the scrap copper alloy mold to remove the surface oxide layer, rust and adhered glass frit;

[0012] (d) Disassembly: disassembly of other material components assembled on the scrap copper alloy mold;

[0013] (e) Primary cleaning: hot-dip cleaning of the scrap copper alloy mold to remove dirt and grease from its surface;

[0014] (f) Secondary cleaning: rinsing the scrap copper alloy mold to remove the surface cleaning agent;

[0015] (g) Drying: Drying the scrap copper alloy mold;

[0016] The following steps are also included:

[0017] (h) Primary smelting: adding the waste copper alloy mold to a medium frequency electric furnace and smelting to 1200-1250°C, adding a 3-5 cm thick covering agent to the surface of the molten copper and blowing in an inert gas for purification; adding a slag remover to remove the slag, then adding a refining agent of 0.5-1.0% by mass of the copper liquid, and after refining, removing the slag again, raising the temperature to 1300-1350°C, and casting to obtain a molten copper ingot;

[0018] (i) Secondary smelting: The composition of the first molten copper ingot is tested, new material is added according to the desired copper alloy composition range, and the trace element Ti is added, and the ingot is smelted to 1230-1280°C, and some flux is added, and scum is removed; the desired copper alloy chemical composition range is tested, and the temperature is raised to 1280-1320°C. The remaining flux is added in advance during subcontracting, and the finished copper alloy mold is cast;

[0019] The mass content range of the required copper alloy chemical composition is Al: 7.5-10.5%, Ni: 13-16%, Zn: 6.5-9.5%, Ti < 0.6%, undesirable impurity elements < 1.0%, and the rest is copper.

[0020] Optimally, in step (h), a graphite tube with a diameter of 20 to 30 mm is used to blow an inert gas into the bottom of the molten copper solution, and then a slag remover is added to remove slag floating on the surface; the inert gas blown in is high-purity argon, and the blowing rate of the high-purity argon is 10 to 30 L / min and the blowing time is 20 to 30 min.

[0021] Optimally, in step (i), the flux is zinc chloride, the amount of which is 0.5-0.8% of the mass of the molten copper, 1 / 2 of which is added after smelting to 1230-1280°C, and another 1 / 2 is added during the transfer process.

[0022] Furthermore, in step (h), the mass percentages of the components of the covering agent are: 40-60% graphite crucible fragments, 15-25% magnesium boride, and 20-35% calcium carbide.

[0023] Optimally, in step (b), a portable spectrometer is used to detect the composition of the copper alloy mold, and the aluminum-nickel-zinc-copper alloy mold is selected as the copper alloy mold material that needs to be further smelted.

[0024] Optimally, in step (c), the sandblasting process is dry blasting, the abrasive is 2.0-3.5 mm quartz sand, the compressed air pressure is 0.2-0.5 MPa, and the sandblasting time is 30-45 min.

[0025] Optimally, in step (e), the first cleaning is ultrasonic hot immersion cleaning, the ultrasonic frequency is 20-40 kHz, the heating temperature is 100-150° C., a cleaning agent is added at a concentration of 15-25% of the clean water content, and the cleaning time is 35 minutes to 1 hour; the mass percentage of the components of the cleaning agent is: 60-80% petroleum solvent cleaning fluid, 5-10% rust preventive oil, and 10-35% trichloroethylene.

[0026] Furthermore, in step (f), the secondary cleaning process is ultrasonic rinsing with clean water, the frequency of the ultrasonic wave is 10-20 KHz, and the cleaning time is 20-45 minutes.

[0027] Optimally, in step (h), the weight percentages of the components of the refining agent are: 15-30% sodium carbonate, 5-10% borax, 15-25% sodium chloride and 50-65% calcium fluoride, and the refining agent is dried before use.

[0028] Furthermore, in step (h), the refining temperature is 1220-1380° C., and the refining time is 1-2 hours.

[0029] The present invention provides a smelting method for recycling waste copper alloys. By coordinating various process steps, especially the primary smelting and the secondary smelting, the copper liquid is kept pure. By continuously blowing in an inert gas, bubbles continuously float and tumble to disturb the copper liquid. Hydrogen, copper oxide, cuprous oxide and other products dissolved at the bottom of the copper liquid float up to the liquid surface and are continuously absorbed by carbon atoms in a covering agent to form solids, ultimately forming scum, which is removed by a slag remover. Furthermore, insoluble oxidation products are removed by refining. Although burnout of the smelted copper alloy material is unavoidable, the copper ingot undergoes secondary smelting and some new material is added to stabilize its composition. At the same time, a trace amount of Ti is added. Ti and other alloying elements can form fine and dense compounds, making the microstructure uniformly dispersed. Ti also serves as a nucleation point for the copper alloy, refines the microstructure grains, and improves the mechanical properties of the microstructure, such as stability, toughness, and yield strength. Therefore, the above method can maximize the utilization of waste copper alloy glass molds and maintain stable quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A flow chart of the smelting method used to regenerate scrap copper alloys according to the present invention;

[0031] Figure 2 A local metallographic diagram of a product having pores obtained by the smelting method used in the present invention to regenerate waste copper alloy (Comparative Example 1). DETAILED DESCRIPTION

[0032] The invention discloses a smelting method for recycling waste copper alloy, comprising the following steps: (a) sorting: sorting various molds to select waste copper alloy molds; (b) selecting: performing composition detection on the waste copper alloy molds to select waste copper alloy molds close to or within the required copper alloy composition range; (c) sandblasting: sandblasting the waste copper alloy molds to remove the oxide layer, rust and adhered glass material on the surface; (d) disassembling: disassembling other material components assembled on the waste copper alloy molds; (e) primary cleaning: hot-dip washing the waste copper alloy molds to remove dirt and grease on the surface; (f) secondary cleaning: rinsing the waste copper alloy molds to remove the surface cleaning agent; (g) drying: drying the waste copper alloy molds; (h) primary smelting: adding the waste copper alloy molds to a medium frequency electric furnace, smelting to 1200-1250° C., and then A 3-5 cm thick covering agent is added to the surface of the molten copper and an inert gas is blown into the molten copper for purification; a slag remover is added for slag removal, and then a refining agent is added in an amount of 0.5-1.0% by mass of the molten copper. After refining, the slag is removed again, the temperature is raised to 1300-1350° C., and a molten copper ingot is cast; (i) secondary smelting: the composition of the molten copper ingot is detected, new material is added according to the desired copper alloy composition range, and trace element Ti is added, the molten copper ingot is smelted to 1230-1280° C., a portion of flux is added, and scum is removed; the desired copper alloy chemical composition range is detected, the temperature is raised to 1280-1320° C., the remaining flux is added in advance in the subcontractor, and a finished copper alloy mold is cast; the mass content range of the desired copper alloy chemical composition is Al: 7.5-10.5%, Ni: 13-16%, Zn: 6.5-9.5%, Ti <0.6%, undesirable impurity elements <1.0%, and the remainder is copper. Through the coordination of various process steps, especially the coordination of primary smelting and secondary smelting, the copper liquid is kept pure. By continuously blowing in inert gas, bubbles continuously float and roll to disturb the copper liquid, and products such as hydrogen, copper oxide, and cuprous oxide dissolved at the bottom of the copper liquid float up to the liquid surface, where they are continuously absorbed by carbon atoms in the covering agent to form solid matter, eventually forming slag, which is removed by a slag remover. Then, through refining, insoluble oxidation products are removed. Although burnout of smelted copper alloy materials is inevitable, the copper ingot undergoes secondary smelting and some new materials are added to stabilize its composition. At the same time, a trace amount of Ti is added. Ti and other alloying elements can form fine and dense compounds, making the microstructure uniformly dispersed. Ti also acts as a nucleation point for the copper alloy, refining the microstructure grains and improving its mechanical properties such as stability, toughness, and yield strength. Therefore, the above method can maximize the utilization of waste copper alloy glass molds with stable quality.

[0033] In step (h), a graphite tube with a diameter of 20-30 mm is used to blow an inert gas into the bottom of the molten copper, and a slag remover is added to remove scum floating on the surface. The inert gas blown in is high-purity argon, and the blowing rate is 10-30 L / min for 20-30 minutes. The inert gas generates bubbles during the rising process, which stir the molten copper and carry suspended inclusions to the surface, thereby further purifying the copper. In step (i), the flux is zinc chloride, which is used in an amount of 0.5-0.8% of the mass of the copper. Half of the flux is added after smelting to 1230-1280°C, and another half is added in the transfer bag. At this time, the active metals such as aluminum and zinc in the copper are oxidized, producing products such as aluminum oxide, which are suspended on the copper surface. The zinc chloride can degas and adsorb the aluminum oxide suspended on the surface. In step (h), the mass percentages of the covering agent components are: 40-60% graphite crucible fragments, 15-25% magnesium boride, and 20-35% calcium carbide. The optimally formulated covering agent isolates the copper alloy from the furnace gases, providing insulation and preventing burnout and oxidation of alloying elements. This creates surface scum that is easily removed. In step (b), a portable spectrometer is used to analyze the composition of the copper alloy mold, and an aluminum-nickel-zinc-copper alloy mold is selected as the copper alloy mold material for further smelting. In step (c), the sandblasting process is dry blasting, using 2.0-3.5 mm quartz sand as the abrasive, a compressed air pressure of 0.2-0.5 MPa, and a blasting time of 30-45 minutes. This sandblasting process fully removes oxidized impurities from the surface of the scrap copper alloy. In step (e), the primary cleaning step is ultrasonic hot immersion cleaning, with an ultrasonic frequency of 20-40 kHz and a heating temperature of 100-150°C. A cleaning agent is added at a concentration of 15-25% clean water, and the cleaning time is 35 minutes to 1 hour. The weight percentage of the cleaning agent components is: 60-80% petroleum solvent cleaning fluid, 5-10% rust preventive oil, and 10-35% trichloroethylene. This rapidly removes oil, rust, and other contaminants from the scrap copper alloy without causing new rust. In step (f), the secondary cleaning step is ultrasonic rinsing with clean water, with an ultrasonic frequency of 10-20 kHz and a cleaning time of 20-45 minutes, to completely rinse the cleaning agent from the copper alloy surface. In step (h), the refining agent comprises the following components by weight: 15-30% sodium carbonate, 5-10% borax, 15-25% sodium chloride, and 50-65% calcium fluoride. The refining agent is dried before use. This allows the calcium fluoride to remove Al2O3 inclusions from the copper melt. Al2O3 + CaF = 3CaO + 2AlF3↑, effectively adsorbing Al2O3 and achieving improved refining results. In step (h), the refining temperature is 1220-1380°C for 1-2 hours, completely removing oxides from the copper melt.

[0034] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings. Example 1

[0035] like Figure 1 As shown, this embodiment provides a smelting method for recycling waste copper alloy, comprising the following steps:

[0036] (a) Sorting: sorting various molds and selecting scrap copper alloy molds. Since recycled scrap copper alloy molds may be mixed with molds of other materials, resulting in large differences in material composition, it is necessary to first sort the copper alloy molds to remove cast iron molds, stainless steel molds, etc. mixed in the scrap copper alloy molds.

[0037] (b) Selection: Detecting the composition of the waste copper alloy molds and selecting waste copper alloy molds that are close to or within the required copper alloy composition range; specifically, determining the composition range of the copper alloy material to be smelted (in the glass mold industry, the mainstream copper alloy material is the aluminum-nickel-zinc series copper alloy, so the aluminum-nickel-zinc series copper alloy can be selected), detecting the composition of the sorted waste copper alloy molds (detection is carried out using a portable spectrometer, which is more intuitive for material composition detection), and selecting copper alloy molds with a composition range within the aluminum-nickel-zinc series as the material for the copper alloy molds to be further smelted;

[0038] (c) Sandblasting: The selected scrap copper alloy molds are sandblasted using dry sandblasting, with 2.0 mm quartz sand as the abrasive, compressed air pressure of 0.2 MPa, and sandblasting time of 35 min to remove surface oxide layers, rust, adhered glass materials, etc., and also to clean impurities on the surface of the scrap copper alloy molds;

[0039] (d) Disassembly: Since the glass mold needs to be assembled with the bottle making machine before the bottle can be made, the corresponding parts on the glass mold body will be assembled with accessories of different materials. Therefore, the mold needs to be further disassembled after sandblasting to remove parts such as hanging nails and joints;

[0040] (e) Primary cleaning: The disassembled scrap copper alloy mold is subjected to ultrasonic hot dip cleaning at an ultrasonic frequency of 20 kHz and a heating temperature of 100°C. A cleaning agent (the mass percentages of the cleaning agent components are: 64% petroleum solvent cleaning fluid, 6% rust-proof oil, and 30% trichloroethylene) accounting for 15% (by mass) of the clean water content is added. The cleaning time is 35 minutes. The scrap copper alloy mold is stripped of dirt and grease on its surface under the combined effects of ultrasonic vibration and radiation and the cleaning agent.

[0041] (f) Secondary cleaning: The scrap copper alloy mold after the above-mentioned primary cleaning is subjected to a second ultrasonic rinse. The medium for this cleaning is clean water, the ultrasonic frequency is 10KHz, and the cleaning time is 25 minutes to wash away the surface cleaning agent, etc.;

[0042] (g) Drying: Drying the cleaned waste copper alloy mold by using propane baking at a temperature of 200°C and a baking time of 25 minutes;

[0043] (h) Primary smelting: The above waste copper alloy molds are placed in a medium frequency electric furnace for smelting, and a composite purification process (specifically, a covering agent combined with an inert gas) is adopted. The smelting temperature is 1200°C, and a covering agent with a thickness of 3 cm is evenly added to the surface of the molten copper (the mass percentage of the covering agent is: 55% graphite crucible fragments, 25% magnesium boride and 20% calcium carbide); after the covering agent is added, an inert gas (commercially available high-purity argon, 99.999%) is blown into the molten copper through a graphite tube with a diameter of 25 mm for purification (the blowing of high-purity argon is carried out). The slag produced in the copper liquid was floated, and then a slag remover (Ishikawa F2) was added to remove the slag. Then, a refining agent (0.5% of the mass of the molten copper water, the mass percentages of the raw materials in the refining agent being: 20% sodium carbonate, 5% borax, 25% sodium chloride and 50% calcium fluoride; dried before use) was added to enhance the purification effect. The refining temperature was 1225°C and the refining time was 1 hour. Then, the slag was removed again, the temperature was raised to 1310°C, and a molten copper ingot was cast.

[0044] (i) Secondary smelting: Based on the above-mentioned copper ingot to be used (i.e., the first-melt copper ingot), its composition is tested and the burn-out rate of various elements is calculated: Specifically, the copper ingot is melted to a molten state, and new material is added according to the percentage of material to be smelted. When adding the new material, the new material is pressed into the copper liquid below the liquid surface in order according to the burn-out susceptibility of each metal element and stirred evenly. The trace element Ti is added, and the copper is melted to 1230°C. 1 / 2 of the flux zinc chloride (ZnCl2; the flux is pre-melted before use, and the total added amount accounts for 0.5% of the copper liquid) is added. The scum is removed, and the chemical composition required for the final corresponding copper alloy mold is tested. The temperature is raised to 1280°C, and another 1 / 2 of the flux is added in advance in the subcontractor. The finished copper alloy mold is obtained by subcontractor casting. The final composition (by mass content) of the copper alloy mold is: Al: 7.8%, Ni: 13.4%, Zn: 6.8%, Ti: 0.14%, undesirable impurity elements are <0.5%, and the remainder is copper. Example 2

[0045] This embodiment provides a smelting method for recycling waste copper alloy. It is basically the same as that in Example 1, except that the process parameters in each step are different, as follows:

[0046] In step (c), the sandblasting parameters are: 3.5 mm quartz sand as abrasive, 0.5 MPa of compressed air pressure, and 45 min of sandblasting time to remove surface oxide layers, rust, adhered glass frit, etc., and to clean impurities on the surface of the scrap copper alloy mold;

[0047] In step (e), the ultrasonic frequency is 40 kHz, the heating temperature is 150°C, and a cleaning agent (the mass percentage of the cleaning agent is: 70% petroleum solvent cleaning fluid, 10% rust preventive oil and 20% trichloroethylene) accounting for 25% of the clean water content is added, and the cleaning time is 1 hour;

[0048] In step (f), the frequency of the ultrasonic wave is 20 kHz, and the cleaning time is 45 minutes to remove the surface cleaning agent, etc.;

[0049] In step (g), the cleaned waste copper alloy mold is dried by propane baking at a temperature of 350° C. for 35 minutes;

[0050] In step (h), a single smelting process is performed: a composite purification process is used, the process is a covering agent + inert gas, the smelting is performed to 1250 ° C, a covering agent with a uniform thickness of 5 cm is added to the surface of the molten copper (the mass percentage of the covering agent is: 60% graphite crucible fragments, 20% magnesium boride, 20% calcium carbide), and a graphite tube with a diameter of φ25 mm is passed through under the condition of adding the covering agent, and high-purity argon gas is blown into the inert gas for purification (the blowing rate of high-purity argon gas is 30 L / min, and the blowing time is 20 min). The slag in the copper liquid is floated, and then a slag remover (Ishikawa F2) is added for slag removal. Then, a refining agent (1.0% of the mass of the molten copper water, the mass percentage of the refining agent is: 15% sodium carbonate, 10% borax, 15% sodium chloride, 60% calcium fluoride) is added, and dried before use to enhance the purification effect. The refining temperature is 1375°C and the refining time is 2h. Then, the slag is removed again, the temperature is raised to 1350°C, and the copper ingot to be used is cast;

[0051] In step (i), secondary smelting: when adding new material, press it into the copper liquid below the liquid surface according to the degree of burnability of each metal element and stir it evenly, add the trace element Ti, smelt it to 1280°C, add 1 / 2 flux zinc chloride (ZnCl2), the flux is pre-melted before use, and the total added amount accounts for 0.8% of the copper liquid, remove the scum, detect and obtain the chemical composition required for the final corresponding copper alloy mold, heat it to 1320°C, add another 1 / 2 flux in the subcontractor in advance, and obtain the finished copper alloy mold by subcontracting casting. The final composition (mass content) of the copper alloy mold is: Al: 10.3%, Ni: 15.8%, Zn: 9.4%, Ti: 0.14%, undesirable impurity elements are <0.3%, and the rest is copper. Example 3

[0052] This embodiment provides a smelting method for recycling waste copper alloy. It is basically the same as that in Example 1, except that the process parameters in each step are different, as follows:

[0053] In step (c), the sandblasting parameters are: 3.0 mm quartz sand as abrasive, 0.4 MPa of compressed air pressure, and 40 min of sandblasting time to remove surface oxide layers, rust, adhered glass frit, etc., and to clean impurities on the surface of the scrap copper alloy mold;

[0054] In step (e), the ultrasonic frequency is 30 kHz, the heating temperature is 120°C, and a cleaning agent (the mass percentage of the cleaning agent is: 62% petroleum solvent cleaning fluid, 8% rust preventive oil and 30% trichloroethylene) accounting for 20% of the clean water content is added, and the cleaning time is 55 minutes;

[0055] In step (f), the frequency of the ultrasonic wave is 15 kHz, and the cleaning time is 40 minutes to remove the surface cleaning agent, etc.;

[0056] In step (g), the cleaned waste copper alloy mold is dried by propane baking at a temperature of 310° C. for 30 minutes;

[0057] In step (h), a smelting is performed once: a composite purification process is adopted, the process is covering agent + inert gas, smelting to 1230 ° C, adding a covering agent with a uniform thickness of 4 cm on the surface of the molten copper (the mass percentage of the covering agent is: 55% graphite crucible fragments, 20% magnesium boride, 25% calcium carbide), and passing through a graphite tube with a diameter of φ25 mm under the condition of adding the covering agent, and blowing in inert gas high-purity argon for purification (the blowing rate of high-purity argon is 20 L / min, and the blowing time is 20 min). The slag in the copper liquid was floated for 25 minutes, and then a slag remover (Ishikawa F2) was added for slag removal. Then, a refining agent (0.8% of the mass of the molten copper water, the mass percentage of the refining agent being: 21% sodium carbonate, 9% borax, 15% sodium chloride, 55% calcium fluoride) was added and dried before use to enhance the purification effect. The refining temperature was 1310°C and the refining time was 1.5 hours. Then, the slag was removed again, the temperature was raised to 1330°C, and the copper ingot to be used was cast.

[0058] In step (i), secondary smelting: when adding new material, press it into the copper liquid below the liquid surface according to the degree of burnability of each metal element and stir it evenly, add the trace element Ti, smelt it to 1250°C, add 1 / 2 flux zinc chloride (ZnCl2), the flux is pre-melted before use, and the total added amount accounts for 0.7% of the copper liquid, remove the scum, detect and obtain the chemical composition required for the final corresponding copper alloy mold, heat it to 1300°C, add another 1 / 2 flux in the subcontractor in advance, and obtain the finished copper alloy mold by subcontracting casting. The final composition (mass content) of the copper alloy mold is: Al: 9.1%, Ni: 14.3%, Zn: 8.7%, Ti: 0.14%, undesirable impurity elements <0.5%, and the rest is copper. Example 4

[0059] This embodiment provides a smelting method for recycling scrap copper alloy. It is basically the same as that in Example 1, except that the process parameters in each step are different, as follows:

[0060] In step (c), the sandblasting parameters are: 2.5 mm quartz sand as abrasive, 0.25 MPa of compressed air pressure, and 40 min of sandblasting time to remove surface oxide layers, rust, adhered glass frit, etc., and to clean impurities on the surface of the scrap copper alloy mold;

[0061] In step (e), the ultrasonic frequency is 25 kHz, the heating temperature is 120°C, and a cleaning agent (the mass percentage of the cleaning agent is: 68% petroleum solvent cleaning fluid, 10% rust preventive oil and 22% trichloroethylene) accounting for 15% of the clean water content is added, and the cleaning time is 55 minutes;

[0062] In step (f), the frequency of the ultrasonic wave is 15 kHz, and the cleaning time is 40 minutes to remove the surface cleaning agent, etc.;

[0063] In step (g), the cleaned waste copper alloy mold is dried by propane baking at a temperature of 320° C. for 25 minutes;

[0064] In step (h), a smelting is performed once: a composite purification process is adopted, the process is covering agent + inert gas, smelting to 1220 ° C, adding a covering agent with a uniform thickness of 4 cm on the surface of the molten copper (the mass percentage of the covering agent is: 60% graphite crucible fragments, 20% magnesium boride, 20% calcium carbide), and passing through a graphite tube with a diameter of φ25 mm under the condition of adding the covering agent, and blowing in inert gas high-purity argon for purification (the blowing rate of high-purity argon is 25 L / min, and the blowing time is 20 min). The slag in the copper liquid was floated for 25 minutes, and then a slag remover (Ishikawa F2) was added for slag removal. Then, a refining agent (0.8% of the mass of the molten copper water, the mass percentage of the refining agent being: 25% sodium carbonate, 5% borax, 10% sodium chloride, 60% calcium fluoride) was added and dried before use to enhance the purification effect. The refining temperature was 1310°C and the refining time was 1.5 hours. Then, the slag was removed again, the temperature was raised to 1330°C, and the copper ingot to be used was cast.

[0065] In step (i), secondary smelting: when adding new material, press it into the copper liquid below the liquid surface according to the degree of burnability of each metal element and stir it evenly, add the trace element Ti, smelt it to 1255°C, add 1 / 2 flux zinc chloride (ZnCl2), the flux is pre-melted before use, and the total added amount accounts for 0.7% of the copper liquid, remove the scum, detect and obtain the chemical composition required for the final corresponding copper alloy mold, heat it to 1305°C, add another 1 / 2 flux in the subcontractor in advance, and cast it by subcontractor to obtain the finished copper alloy mold. The final composition (mass content) of the copper alloy mold is: Al: 9.8%, Ni: 15.1%, Zn: 7.3%, Ti: 0.11%, undesirable impurity elements are <0.3%, and the rest is copper. Example 5

[0066] This embodiment provides a smelting method for recycling scrap copper alloy. It is basically the same as that in Example 1, except that the process parameters in each step are different, as follows:

[0067] In step (c), the sandblasting parameters are: 3.0 mm quartz sand as abrasive, 0.4 MPa of compressed air pressure, and 40 min of sandblasting time to remove surface oxide layers, rust, adhered glass frit, etc., and to clean impurities on the surface of the scrap copper alloy mold;

[0068] In step (e), the ultrasonic frequency is 35 kHz, the heating temperature is 120°C, and a cleaning agent (the mass percentage of the cleaning agent is: 70% petroleum solvent cleaning fluid, 10% rust preventive oil and 20% trichloroethylene) accounting for 18% of the clean water content is added, and the cleaning time is 40 minutes;

[0069] In step (f), the frequency of the ultrasonic wave is 20 kHz, and the cleaning time is 40 minutes to remove the surface cleaning agent, etc.;

[0070] In step (g), the cleaned waste copper alloy mold is dried by propane baking at a temperature of 310° C. for 30 minutes;

[0071] In step (h), a single smelting process is performed: a composite purification process is used, the process is covering agent + inert gas, smelting to 1235 ° C, adding a covering agent with a uniform thickness of 5 cm on the surface of the molten copper (the mass percentage of the covering agent is: 50% graphite crucible fragments, 20% magnesium boride, 30% calcium carbide), and passing through a graphite tube with a diameter of φ25 mm under the condition of adding the covering agent, and blowing in inert gas high-purity argon gas for purification (the blowing rate of high-purity argon gas is 30 L / min, and the blowing time is 20 min). The slag in the copper liquid was floated for 25 minutes, and then a slag remover (Ishikawa F2) was added for slag removal. Then, a refining agent (1.0% of the mass of the molten copper water, the mass percentage of the refining agent being: 25% sodium carbonate, 5% borax, 15% sodium chloride, 55% calcium fluoride) was added and dried before use to enhance the purification effect. The refining temperature was 1335°C and the refining time was 1.0h. Then, the slag was removed again, the temperature was raised to 1345°C, and the copper ingot to be used was cast.

[0072] In step (i), secondary smelting: when adding new material, press it into the copper liquid below the liquid surface according to the degree of burnability of each metal element and stir it evenly, add the trace element Ti, smelt it to 1270°C, add 1 / 2 flux zinc chloride (ZnCl2), the flux is pre-melted before use, and the total added amount accounts for 0.6% of the copper liquid, remove the scum, detect and obtain the chemical composition required for the final corresponding copper alloy mold, heat it to 1315°C, add another 1 / 2 flux in the subcontractor in advance, and obtain the finished copper alloy mold by subcontracting casting. The final composition (mass content) of the copper alloy mold is: Al: 10.1%, Ni: 14.8%, Zn: 8.3%, Ti: 0.11%, undesirable impurity elements <0.5%, undesirable impurity elements <0.5%, and the rest is copper. Example 6

[0073] This embodiment provides a smelting method for recycling scrap copper alloy. The method is basically the same as that in Example 1, except that the mass percentages of the raw materials in the refining agent are: 15% sodium carbonate, 5% borax, 15% sodium chloride, and 65% calcium fluoride. Example 7

[0074] This embodiment provides a smelting method for recycling scrap copper alloy. The method is basically the same as that in Example 1, except that the mass percentages of the raw materials in the refining agent are: 24% sodium carbonate, 8% borax, 18% sodium chloride, and 50% calcium fluoride.

[0075] Comparative Example 1

[0076] This example provides a smelting method for recycling waste copper alloy, which is basically the same as that in Example 1, except that argon gas is not introduced.

[0077] Comparative Example 2

[0078] This example provides a smelting method for recycling waste copper alloy, which is basically the same as that in Example 1, except that the trace element Ti is not added.

[0079] Comparative Example 3

[0080] This example provides a smelting method for recycling scrap copper alloy. It is basically the same as that in Example 1, except that a covering agent with a uniform thickness of 2 cm is added to the surface of the molten copper (the covering agent thickness is insufficient at this time).

[0081] Comparative Example 4

[0082] This example provides a smelting method for recycling scrap copper alloy. It is basically the same as that in Example 1, except that a covering agent with a uniform thickness of 6 cm is added to the surface of the molten copper (the thickness of the covering agent is too large in this case).

[0083] Comparative Example 5

[0084] This example provides a smelting method for recycling waste copper alloy, which is basically the same as that in Example 1, except that no refining agent is added in step (h).

[0085] Comparative Example 6

[0086] This example provides a smelting method for recycling waste copper alloy, which is basically the same as that in Example 1, except that in step (i), the flux zinc chloride is not added.

[0087] The products of Examples 1-7 and Comparative Examples 1-6 were subjected to performance tests, tensile tests were performed in accordance with GB / T 12225-2005 "Technical Conditions for Copper Alloy Castings for General Valves" and surface quality inspections were performed in accordance with GB / T 15117-1994 Copper Alloy Die Castings Standard. The results are shown in Table 1 (the surface condition of Comparative Example 1 is shown in Table 1). Figure 2 ).

[0088] Table 1 Mechanical properties data of each embodiment,

[0089]

[0090] The above examples and comparative examples demonstrate that by appropriately adjusting the chemical composition of the copper alloy and adding a trace amount of Ti, a fine, dense compound is formed with other alloying elements, which is uniformly dispersed and serves as nucleation points for the copper alloy, refining the grain size and improving mechanical properties such as structural stability, toughness, and casting performance. Consequently, the copper alloy exhibits excellent yield strength and elongation. Two cleanings and sandblasting can thoroughly remove oil and oxides from the surface of the waste copper mold. Then, after two smelting cycles, the appropriately proportioned refining agents and additives remove oxidizing substances from the solution, resulting in a finished mold free of pores and blisters.

[0091] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A smelting method for recycling waste copper alloy, comprising the following steps: (a) Sorting: sorting various molds and selecting scrap copper alloy molds; (b) selection: performing composition testing on the waste copper alloy molds to select waste copper alloy molds having a composition close to or within a desired copper alloy composition range; (c) Sandblasting: Sandblasting the scrap copper alloy mold to remove the surface oxide layer, rust and adhered glass frit; (d) Disassembly: disassembly of other material components assembled on the scrap copper alloy mold; (e) Primary cleaning: hot-dip cleaning of the scrap copper alloy mold to remove dirt and grease from its surface; (f) Secondary cleaning: rinsing the scrap copper alloy mold to remove the surface cleaning agent; (g) Drying: Drying the scrap copper alloy mold; It is characterized in that it also includes the following steps: (h) Primary smelting: adding the waste copper alloy mold to a medium frequency electric furnace and smelting to 1200-1250°C, adding a 3-5 cm thick covering agent to the surface of the molten copper and blowing in an inert gas for purification; adding a slag remover to remove the slag, then adding a refining agent of 0.5-1.0% by mass of the copper liquid, and after refining, removing the slag again, raising the temperature to 1300-1350°C, and casting to obtain a molten copper ingot; (i) Secondary smelting: The composition of the first molten copper ingot is tested, new material is added according to the desired copper alloy composition range, and the trace element Ti is added, the smelting temperature is set at 1230-1280°C, 1 / 2 flux is added, and scum is removed; the desired copper alloy chemical composition range is determined by testing, the temperature is raised to 1280-1320°C, the remaining 1 / 2 flux is added in advance during subcontracting, and the finished copper alloy mold is cast; the flux is zinc chloride, and the amount used is 0.5-0.8% of the mass of the molten copper; The mass content range of the required copper alloy chemical composition is Al: 7.5-10.5%, Ni: 13-16%, Zn: 6.5-9.5%, Ti < 0.6%, undesirable impurity elements < 1.0%, and the rest is copper.

2. The smelting method for recycling waste copper alloy according to claim 1, characterized in that: In step (h), an inert gas is blown into the bottom of the molten copper using a graphite tube with a diameter of 20 to 30 mm, and a slag remover is added to remove slag floating on the surface. The inert gas blown in is high-purity argon gas at a rate of 10 to 30 L / min for a time of 20 to 30 minutes.

3. The smelting method for recycling waste copper alloy according to claim 2, characterized in that: In step (h), the mass percentages of the components of the covering agent are: 40-60% graphite crucible fragments, 15-25% magnesium boride, and 20-35% calcium carbide.

4. The smelting method for recycling waste copper alloy according to claim 1, characterized in that: In step (b), a portable spectrometer is used to detect the composition of the copper alloy mold, and the aluminum-nickel-zinc-copper alloy mold is selected as the copper alloy mold material that needs to be further smelted.

5. The smelting method for recycling waste copper alloy according to claim 1, characterized in that: In step (c), the sandblasting process is dry blasting, the abrasive is 2.0-3.5 mm quartz sand, the compressed air pressure is 0.2-0.5 MPa, and the sandblasting time is 30-45 min.

6. The smelting method for recycling waste copper alloy according to claim 1, characterized in that: In step (e), the first cleaning is ultrasonic hot immersion cleaning, the ultrasonic frequency is 20-40 kHz, the heating temperature is 100-150°C, a cleaning agent is added with a content of 15-25% of clean water, and the cleaning time is 35 minutes to 1 hour; the weight percentage of each component of the cleaning agent is: 60-80% petroleum solvent cleaning liquid, 5-10% rust preventive oil and 10-35% trichloroethylene.

7. The smelting method for recycling waste copper alloy according to claim 1 or 6, characterized in that: In step (f), the secondary cleaning process is ultrasonic rinsing with clean water, the frequency of the ultrasonic wave is 10-20KHz, and the cleaning time is 20-45 minutes.

8. The smelting method for recycling waste copper alloy according to claim 1, characterized in that: In step (h), the weight percentage of each component of the refining agent is: 15-30% sodium carbonate, 5-10% borax, 15-25% sodium chloride and 50-65% calcium fluoride, and the refining agent is dried before use.

9. The smelting method for recycling waste copper alloy according to claim 1 or 8, characterized in that: In step (h), the refining temperature is 1220-1380° C., and the refining time is 1-2 hours.

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