A method for preparing copper ingots using scrap copper materials

Abstract

This application provides a method for preparing copper ingots from scrap copper materials, belonging to the field of scrap copper refining. The method includes: adding scrap copper materials and a composite flux into an oxygen-enriched side-blown smelting furnace, and injecting oxygen and fuel through the tuyeres on the side wall of the furnace to obtain a first copper liquid; introducing a mixed gas composed of water vapor and nitrogen into the bottom of the first copper liquid to obtain a second copper liquid; heating the second copper liquid to 1380–1450°C under vacuum conditions, adding titanium-containing and carbon-containing substances to the melt, and simultaneously subjecting the melt to ultrasonic field treatment; adding an aluminum-rare earth alloy to the melt, and continuing ultrasonic field treatment for 5–10 minutes to obtain a nano-reinforced copper-based composite melt; and casting the nano-reinforced copper-based composite melt into an electromagnetic crystallizer to obtain copper ingots. This method achieves high-value recycling of low-quality scrap copper and simultaneously solves the problem of easy agglomeration of the nano-reinforced phase in molten copper.

Description

Technical Field

[0001] This application relates to the field of scrap copper refining and production technology, and in particular to a method for preparing copper ingots using scrap copper materials. Background Technology

[0002] As a key approach to ensuring the sustainable supply of copper resources, the high-value utilization of scrap copper is of great significance for alleviating resource pressure, reducing energy consumption, and reducing pollution. However, the recycling of low-quality scrap copper faces multiple technical bottlenecks: on the one hand, this type of scrap copper has complex sources, containing metallic impurities such as zinc, tin, lead, and iron, as well as organic pollutants such as oil and plastics. The stepwise smelting and refining processes of traditional pyrometallurgical methods are difficult to achieve deep purification, resulting in low product purity and unstable performance. On the other hand, nano-reinforcing phases (such as titanium carbide) introduced to increase the added value of scrap copper products tend to agglomerate due to their high surface energy and weak interfacial bonding with the copper matrix. Existing mechanical dispersion and surface modification technologies cannot effectively disperse them in scrap copper melts with many impurities, which restricts the preparation of high-performance copper-based composite materials.

[0003] Existing technologies struggle to overcome the aforementioned bottlenecks. Taking the patent CN117535523A, "A Method for Preparing Copper Ingots from Waste Copper," as an example, it employs a traditional process of pretreatment-calcination-refining-vacuum melting. While this process can treat waste copper through multiple steps, it has significant limitations: the process is lengthy and energy-intensive, requiring six high-temperature steps, resulting in low production efficiency; its purification capacity is limited, failing to effectively remove difficult-to-remove impurities such as lead and tin, making it difficult to meet the purity requirements of high-performance materials; furthermore, it does not involve the introduction and dispersion design of nano-reinforcing phases, limiting the product to low-to-mid-end applications such as bathroom fixtures, and failing to upgrade from low-quality waste copper to high-end composite materials. Therefore, the industry urgently needs an innovative process that can simultaneously solve the problems of deep purification of low-quality waste copper and the agglomeration of nano-reinforcing phases, in order to achieve efficient and high-value utilization of waste copper resources. Summary of the Invention

[0004] This application provides a method for preparing copper ingots using waste copper materials to solve the following technical problems: how to achieve high-value recycling of low-quality waste copper, and simultaneously solve the problem of easy agglomeration of nano-reinforced phases in molten copper.

[0005] This application provides a method for preparing copper ingots using scrap copper materials, the method comprising the following steps:

[0006] S1. The pretreated waste copper material and composite flux are added to an oxygen-enriched side-blown smelting furnace, and oxygen and fuel are injected from the tuyeres on the side wall of the furnace to simultaneously melt, oxidize and slag-refine the waste copper material to obtain the first copper liquid; the composite flux is composed of quartz sand, calcium phosphate, lime and fluorite.

[0007] S2. The first copper liquid is transferred into a refining furnace, and a mixed gas consisting of water vapor and nitrogen is introduced from the bottom of the refining furnace to remove tin and zinc impurities from the first copper liquid, thereby obtaining a second copper liquid.

[0008] S3. Under vacuum conditions, the second copper liquid is heated to 1380-1450°C, titanium-containing and carbon-containing substances are added to the melt, and the melt is simultaneously subjected to ultrasonic field treatment.

[0009] S4. When the ultrasonic field treatment time reaches 10-15 min, aluminum rare earth alloy is added to the melt, and the ultrasonic field treatment is continued for 5-10 min, so that nano-scale titanium carbide reinforcing phase is generated in the melt through in-situ reaction, and nano-reinforced copper-based composite melt is obtained.

[0010] S5. The nano-reinforced copper-based composite melt is introduced into an electromagnetic crystallizer for casting and solidification under the electromagnetic pressure generated by the alternating magnetic field to obtain copper ingots.

[0011] Optionally, in step S1, the melting, oxidation, and slag refining temperature is 1500–1680°C, and the time is 30–60 min.

[0012] Optionally, in step S1, the oxygen is oxygen-enriched air with a volume concentration > 90%, and the fuel is natural gas or pulverized coal.

[0013] Optionally, in step S1, the mass of the quartz sand is 40-60% of the total mass of the composite flux, the mass of the calcium phosphate is 10-20% of the total mass of the composite flux, the mass of the lime is 15-25% of the total mass of the composite flux, and the mass of the fluorite is 5-10% of the total mass of the composite flux.

[0014] Optionally, in step S2, the volume of the water vapor is 10-30% of the total volume of the mixed gas, and the volume of the nitrogen gas is 70-90% of the total volume of the mixed gas.

[0015] The temperature of the mixed gas introduced from the bottom of the refining furnace is 1250–1300°C, and the time is 20–40 minutes.

[0016] Optionally, in step S3, the titanium-containing material is a copper-titanium master alloy, and the carbon-containing material is high-purity graphite powder;

[0017] The molar ratio of Ti in the titanium-containing material to C in the carbon-containing material is 1:(0.9 to 1.1).

[0018] Optionally, in step S3, the frequency of the ultrasonic field treatment is 20–25 kHz, and the power is 5–20 kW.

[0019] Optionally, in step S4, the mass of the aluminum rare earth alloy is 0.1% to 0.3% of the mass of the melt;

[0020] In the aluminum-rare earth alloy, the mass content of aluminum is ≥70%, and the mass content of rare earth elements is 5% to 15%.

[0021] Optionally, in step S5, the alternating magnetic field generated by the electromagnetic crystallizer has a frequency of 50-60 Hz and a magnetic field strength of 0.01-0.05 T.

[0022] The casting temperature is 1000–1100℃.

[0023] Optionally, in step S5, the copper ingot is internally dispersed with a nano-scale titanium carbide reinforcing phase, with an average grain size ≤50μm, tensile strength ≥350MPa, and conductivity ≥85%IACS.

[0024] The technical solutions provided in this application have the following advantages compared with the prior art:

[0025] This application provides a method for preparing copper ingots using waste copper materials. It overcomes the bottleneck of complex composition and difficult removal of impurities in waste copper through "step-by-step deep purification", and solves the problem of nano-reinforced phase agglomeration by "in-situ synthesis + external field assistance" technology. Finally, it retains performance advantages through precise shaping, forming a synergistic solution for the entire process.

[0026] In the purification of low-quality scrap copper, a combined process of "molecular capture flux + controlled oxygen potential gas-phase refining" is used to achieve deep impurity removal. For harmful impurities such as lead, which are difficult to remove efficiently using traditional processes, a composite flux containing calcium phosphate is used in the oxygen-enriched side-blown smelting stage. Utilizing the "molecular capture" properties of calcium phosphate, it selectively reacts with Pb in the melt to generate stable lead phosphate, which enters the slag phase, achieving targeted deep purification. To further remove volatile and difficult-to-oxidize residual impurities such as tin and zinc, a gas-phase transport refining step is introduced. By introducing a specific ratio of nitrogen-water vapor mixture into the refining furnace and precisely controlling the water vapor partial pressure (oxygen potential), Sn and Zn are selectively oxidized to SnO2 and ZnO (or volatilized or slag-forming), while avoiding excessive oxidation of copper. This achieves green and efficient deep purification and provides a high-purity copper matrix for subsequent performance enhancement, which is a fundamental prerequisite for the transformation of low-quality scrap copper into high-performance materials.

[0027] To address the agglomeration problem of nano-reinforced phase (TiC), an innovative technical approach of "ultrasound-assisted in-situ synthesis + timing optimization" was adopted. Unlike traditional physical mixing methods for nanoparticles, this method involves adding a copper-titanium master alloy and high-purity graphite powder to a purified copper melt under vacuum conditions. A high-temperature-triggered in-situ reaction (Ti+C→TiC) directly generates a nanoscale TiC reinforcing phase within the copper matrix, preventing agglomeration caused by excessive surface energy when nanoparticles are added externally. Simultaneously applied high-power ultrasonic fields utilize the "cavitation effect" (the instantaneous rupture of tiny bubbles in the melt generating localized high pressure) to accelerate the reaction process and disperse initially formed TiC agglomerates. The "acoustic flow effect" (driving intense convection in the melt) then ensures uniform dispersion of the nano-TiC particles within the copper matrix. Furthermore, by optimizing the timing of the aluminum-rare earth alloy addition, premature oxidation and failure of the reactive rare earth elements are prevented. The rare earth elements also refine the grain size and improve the interfacial bonding between TiC and the copper matrix, further stabilizing the dispersion of the nano-reinforcing phase. This achieves multi-dimensional reinforcement through "particle dispersion + interface optimization + grain refinement."

[0028] Ultimately, the forming process is achieved through electromagnetic soft-contact casting technology. This technology utilizes the electromagnetic force generated by an alternating magnetic field to achieve "soft contact" between the molten copper and the crystallizer wall, avoiding surface defects (cold shuts, vibration marks) and internal segregation common in traditional casting. This ensures the uniform dispersion of the nano-TiC reinforcing phase and the density of the copper matrix, fully preserving the superior properties imparted by the initial purification and strengthening processes. The entire process follows the logic of "purification laying the foundation, in-situ synthesis and ultrasonic dispersion overcoming performance bottlenecks, and precise forming realizing value realization," simultaneously achieving the high-value recycling of low-quality scrap copper (transforming complex scrap copper into high-performance composite copper materials) and solving the problem of nano-reinforcing phase agglomeration. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic flowchart illustrating a method for preparing copper ingots using waste copper materials, provided as an embodiment of this application. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0034] Figure 1 This is a schematic flowchart illustrating a method for preparing copper ingots using waste copper materials, provided as an embodiment of this application.

[0035] like Figure 1 As shown, this application provides a method for preparing copper ingots using scrap copper materials, the method comprising the following steps:

[0036] S1. The pretreated waste copper material and composite flux are added to an oxygen-enriched side-blown smelting furnace, and oxygen and fuel are injected from the tuyeres on the side wall of the furnace to simultaneously melt, oxidize and slag-refine the waste copper material to obtain the first copper liquid; the composite flux is composed of quartz sand, calcium phosphate, lime and fluorite.

[0037] S2. The first copper liquid is transferred into a refining furnace, and a mixed gas consisting of water vapor and nitrogen is introduced from the bottom of the refining furnace to remove tin and zinc impurities from the first copper liquid, thereby obtaining a second copper liquid.

[0038] S3. Under vacuum conditions, the second copper liquid is heated to 1380-1450°C, titanium-containing and carbon-containing substances are added to the melt, and the melt is simultaneously subjected to ultrasonic field treatment.

[0039] S4. When the ultrasonic field treatment time reaches 10-15 min, aluminum rare earth alloy is added to the melt, and the ultrasonic field treatment is continued for 5-10 min, so that nano-scale titanium carbide reinforcing phase is generated in the melt through in-situ reaction, and nano-reinforced copper-based composite melt is obtained.

[0040] S5. The nano-reinforced copper-based composite melt is introduced into an electromagnetic crystallizer for casting and solidification under the electromagnetic pressure generated by the alternating magnetic field to obtain copper ingots.

[0041] It should be noted that the functions of steps S1 to S5 in this application are as follows:

[0042] (1) Step S1: Oxygen-enriched side-blown smelting-refining integration. Step S1 is the "pretreatment core" of the whole process, and it undertakes the key task of converting complex waste copper into preliminary purified copper liquid. By combining "oxygen-enriched side-blowing technology + molecular-capturing composite flux," it breaks through the limitations of traditional step-by-step smelting and refining, simultaneously achieving three major functions: First, by utilizing the high-concentration oxygen and fuel injected through the side wall tuyeres, a high-temperature, strongly oxidizing, and violently agitated environment is created in the molten pool, causing the scrap copper to melt rapidly. At the same time, the organic matter in the scrap is instantly vaporized and burned, preventing its residue from affecting the purity of the copper liquid. Second, by utilizing the strong oxidizing atmosphere, common harmful impurities such as iron, zinc, and lead are oxidized into oxides (such as Fe→FeO, Pb→PbO). Third, through the synergistic effect of the composite flux, quartz sand, lime, and fluorite construct a low-melting-point slag system, which encapsulates oxidized impurities such as iron and zinc into the slag phase. Meanwhile, calcium phosphate captures impurities such as lead and bismuth, which are difficult to remove by traditional methods, through specific chemical reactions, generating stable phosphate compounds that are fixed in the slag. Finally, by skimming the slag, the copper liquid and impurities are efficiently separated, providing a relatively stable first copper liquid for subsequent deep impurity removal.

[0043] (2) Step S2: Controllable oxygen potential gas-phase deep refining. Step S2 is the "precision purification unit" of the process, focusing on solving the residual impurities such as tin and zinc that were not completely removed in step S1. Since tin is more difficult to oxidize than iron and zinc, it is easy to form unstable oxides in the strong oxidizing environment of S1, which are difficult to be completely adsorbed by the slag. The traditional method of adding solid oxidants to remove impurities will generate additional solid waste. Therefore, this step innovatively adopts the gas-phase refining technology of "bottom introduction of water vapor-nitrogen mixed gas": by precisely controlling the proportion of water vapor (i.e. oxygen potential) in the mixed gas, tin and zinc undergo selective oxidation reactions with water vapor in a thermodynamically controllable environment, such as Sn + 2H2O(g) → SnO2(s) + 2H2(g). The generated solid oxides such as tin dioxide can easily float to the surface and form slag. Nitrogen plays the role of diluting water vapor, stabilizing the airflow, and safely discharging the hydrogen produced by the reaction. This "gas-instead-of-solid" method can precisely remove target impurities and avoid secondary pollution, increasing the purity of the first copper liquid to over 99.9%, thus providing a high-purity matrix (second copper liquid) for the subsequent preparation of high-performance materials.

[0044] (3) Steps S3 and S4: Ultrasonic-assisted in-situ synthesis and composite modification integrated treatment. Steps S3 and S4 together constitute the "performance design center" of the process, breaking through the limitation of traditional copper ingot production of "only purification, not strengthening", and actively improving the performance of copper liquid through materials science. Among them, S3 plays the role of "initiating reaction and preliminary dispersion": under vacuum conditions, after the second copper liquid is heated to a specific temperature, copper-titanium intermediate alloy (Ti source) and high-purity graphite powder (C source) are added. The in-situ reaction of Ti and C is activated by high temperature (Ti+C→TiC) to generate nanoscale titanium carbide (TiC) reinforcing phase; at the same time, ultrasonic field treatment is started, and the reaction process is accelerated by the "cavitation effect" of ultrasound, and the trace gas remaining in the melt is removed. The newly generated TiC nanoparticle agglomerates are dispersed by the "acoustic flow effect", so that they are initially uniformly dispersed in the copper matrix. S4 is responsible for "optimizing performance and stabilizing dispersion": after S3 ultrasonic treatment for 10-15 minutes and the TiC particles are initially dispersed, aluminum rare earth alloy is added. Aluminum can further purify the melt (reacting with residual oxygen to generate Al2O3), and rare earth elements (such as La and Ce) can be adsorbed on the surface of TiC particles, improving their interfacial bonding with the copper matrix, and can also serve as a heterogeneous nucleation core to refine copper grains. The continuous ultrasonic treatment for 5-10 minutes ensures that the aluminum rare earth alloy is uniformly dispersed, and finally forms a nano-reinforced copper-based composite melt with "nano-TiC reinforcement + grain refinement", realizing the leap of copper materials from "pure metal" to "high-performance composite material".

[0045] (4) Step S5: Electromagnetic soft contact casting. Step S5 is the "quality landing terminal" of the process. Its core task is to transform the performance-enhanced nano-reinforced copper-based composite melt into a copper ingot with "high-quality surface and dense interior". In traditional casting, the copper liquid is in direct contact with the crystallizer wall, which is prone to surface defects such as "cold shut" and "vibration marks" due to uneven cooling. Moreover, internal component segregation is prone to occur, resulting in the loss of the performance enhancement effect in the early stage. This step uses an electromagnetic crystallizer. By winding a coil around the outside of the crystallizer and passing an alternating current, an alternating electromagnetic field is generated. The electromagnetic field induces a current in the copper liquid, forming an electromagnetic pressure (Lorentz force) pointing towards the center of the melt, so that the copper liquid and the crystallizer wall achieve "soft contact" (no direct friction), which completely eliminates the surface defects of traditional casting. At the same time, the electromagnetic pressure promotes uniform cooling and solidification of the copper liquid, inhibits component segregation, and ensures that the nano-TiC reinforcing phase is uniformly distributed in the ingot and the grain size is stable within a small range. The resulting copper ingots not only have a smooth, mirror-like surface, eliminating the need for subsequent milling and planing processes, but also retain the effects of previous performance enhancements, achieving a synergistic effect of "high strength + high conductivity".

[0046] Meanwhile, the entire process of this application follows the logical chain of "pretreatment → purification → reinforcement → forming", with each step being interconnected and mutually supportive, forming a highly efficient and collaborative technical system.

[0047] (1) S1 and S2: "Broad-spectrum impurity removal - precise impurity removal" work together to lay the foundation for high purity. S1 removes more than 80% of impurities (organic matter, iron, zinc, lead, etc.) from waste copper through oxygen-enriched side blowing and molecular trapping flux, which greatly reduces the impurity removal load of S2. This allows S2 to focus on removing tin and zinc residues that are difficult to remove completely by S1 without having to deal with complex and diverse impurities. This division of labor of "broad-spectrum first, then precise" not only ensures the overall impurity removal efficiency (S1 shortens the processing time, and S2 avoids the energy waste caused by over-refining), but also ensures that the purity of the final copper liquid meets the requirements for the preparation of high-performance materials. If the pretreatment of S1 is not performed, S2 will have to deal with multiple impurities at the same time, which will not only prolong the refining time, but may also lead to incomplete impurity removal due to mutual interference between impurities. If there is no deep purification of S2, the tin, zinc and other impurities remaining in S1 will react with Ti, C and rare earth elements in S3 / S4 to generate ineffective compounds, destroy the formation of nano-reinforcing phase, and lead to performance enhancement failure.

[0048] (2) S2, S3, and S4: The synergy between "high-purity matrix and high-efficiency performance enhancement" ensures the enhancement effect. The high-purity copper liquid produced by S2 (purity ≥ 99.9%) is the prerequisite for S3 and S4 to achieve high-efficiency performance enhancement. On the one hand, the low impurity content avoids the consumption of functional elements such as Ti, C, and rare earth by impurities (such as impurities reacting with Ti to generate non-reinforcing phases), ensuring that they are all used for in-situ reaction (generating TiC) and modification treatment (refining grains). On the other hand, the pure matrix reduces the "contamination points" of nano-TiC particles, avoiding impurities adsorbing on the particle surface and causing agglomeration, and ensuring the dispersion effect of the ultrasonic field on the particles. Conversely, the performance enhancement process of S3 and S4 also fully utilizes the value of the high-purity matrix of S2. If the high-purity copper liquid is only used to produce ordinary copper ingots, it will cause a waste of resources. However, through in-situ synthesis and composite modification, the "potential" of the high-purity matrix can be transformed into "actual performance advantages" and increase the added value of the product.

[0049] (3) S3 and S4 with S5: "High-performance melt - high-quality forming" synergistically realizes value realization. The nano-reinforced copper-based composite melt prepared by S3 and S4 has the characteristics of "high hardness and easy brittleness", which has extremely high requirements for the forming process: if traditional casting is used, surface defects and internal segregation will lead to uneven mechanical properties of the ingot, and even cracks, and the performance enhancement effect in the early stage will be completely lost. The electromagnetic soft contact casting of S5 is perfectly adapted to this high-performance melt: the "soft contact" method avoids direct friction between the copper liquid and the crystallizer wall, preventing the brittle and hard nano-reinforcement phase from cracking on the surface of the ingot; the uniform solidification process ensures that the nano TiC particles and grains are evenly distributed in the ingot, so that the performance enhancement effect runs through the entire ingot. At the same time, the refined grain structure formed by S3 and S4 also reduces the difficulty of solidification control of S5. The fine grains can reduce solidification shrinkage stress and further inhibit crack generation. The two work together to achieve a stable transformation from "high-performance melt to high-quality ingot", so that the technical advantages of the entire process are ultimately reflected in the product.

[0050] In some embodiments, the pretreatment in step S1 includes: crushing, washing, flotation, hot air drying, and magnetic separation to obtain copper scrap with a particle size of <30mm.

[0051] In some embodiments, in step S1, the melting, oxidation, and slag refining temperature is 1500–1680°C, and the time is 30–60 min.

[0052] The smelting temperature is limited to 1500–1680℃. On the one hand, the temperature is much higher than the melting point of copper (1083℃), which can ensure that the scrap copper and composite flux melt quickly and completely, and can activate the reaction of calcium phosphate with lead and bismuth, thus enhancing the targeted impurity removal effect. On the other hand, the upper limit is controlled at 1680℃, which can avoid copper liquid volatilization loss (reducing raw material waste), accelerated furnace lining corrosion (reducing equipment maintenance costs), and excessive zinc volatilization (facilitating the recovery of zinc in the flue gas).

[0053] The smelting time is limited to 30-60 minutes. Relying on the characteristics of "strong stirring and high oxidation" of the oxygen-enriched side-blown furnace, this time is sufficient to complete the entire process of "waste copper melting - organic matter combustion - impurity oxidation - slag separation". This is significantly shortened compared to the traditional process (several hours), and production efficiency is significantly improved. At the same time, this time length can ensure that impurities and flux react fully and avoid impurity residue due to insufficient time, thus achieving a balance between "high efficiency" and "thoroughness".

[0054] In some embodiments, in step S1, the oxygen is oxygen-enriched air with a volume concentration > 90%, and the fuel is natural gas or pulverized coal.

[0055] Limiting the oxygen concentration to a volume concentration of >90% serves several purposes: first, it accelerates fuel combustion, rapidly increases the temperature of the molten pool, and reduces fuel consumption; second, it enhances the oxidation reaction rate of impurities, enabling impurities such as iron and zinc to be converted into oxides in a short time; and third, the high-speed injection of oxygen enhances the stirring effect of the molten pool, promotes the mixing of copper liquid and flux, and improves slag formation and impurity removal efficiency.

[0056] In some embodiments, in step S1, the mass of the quartz sand is 40-60% of the total mass of the composite flux, the mass of the calcium phosphate is 10-20% of the total mass of the composite flux, the mass of the lime is 15-25% of the total mass of the composite flux, and the mass of the fluorite is 5-10% of the total mass of the composite flux.

[0057] The specified composite flux ratio is 40-60% quartz sand, 10-20% calcium phosphate, 15-25% lime, and 5-10% fluorite. The proportions of each component are precisely designed to work synergistically for optimal effect. Quartz sand, as the "skeleton" of the slag, reacts with oxidizing impurities such as FeO to form low-melting-point iron silicates, providing a basic carrier for impurity removal. The proportion of calcium phosphate ensures sufficient reaction capacity to efficiently capture impurities such as lead and bismuth, achieving deep impurity removal. Lime adjusts the slag alkalinity to prevent acidic slag from corroding the furnace body, while also improving slag fluidity. Fluorite further optimizes the slag-copper separation effect by lowering the slag melting point and viscosity, reducing the entrainment loss of copper liquid in the slag.

[0058] In some embodiments, in step S2, the volume of the water vapor is 10-30% of the total volume of the mixed gas, and the volume of the nitrogen gas is 70-90% of the total volume of the mixed gas.

[0059] The temperature of the mixed gas introduced from the bottom of the refining furnace is 1250–1300°C, and the time is 20–40 minutes.

[0060] The specified mixed gas ratio is 10-30% water vapor and 70-90% nitrogen. Water vapor provides the oxygen source required for impurity removal, ensuring that the oxygen potential in the furnace can only oxidize tin and zinc (target impurities) and not copper (the main metal), thus avoiding a decrease in the purity of the copper liquid due to its own oxidation. Nitrogen, as an inert dilution gas, can stabilize the gas flow pressure, prevent fluctuations in water vapor concentration from causing oxygen potential to run out of control, and at the same time carry away the hydrogen generated in the reaction (avoiding the accumulation of hydrogen and the resulting safety hazards), thus achieving green and environmentally friendly impurity removal.

[0061] The ventilation temperature is limited to 1250-1300℃. This serves two purposes: first, to ensure the copper liquid maintains good fluidity, allowing the water vapor-nitrogen mixture to fully contact the copper liquid and improve reaction efficiency; second, to prevent excessive volatilization of the copper liquid by keeping the temperature lower than the S1 melting temperature, while also inhibiting the reaction between copper and water vapor (the critical temperature for copper oxidation is above 1300℃), ensuring that the impurity removal process targets only tin and zinc and does not affect the main components of the copper liquid.

[0062] The ventilation time is limited to 20-40 minutes. This time length ensures that tin, zinc and water vapor react fully (the generated SnO2 and other oxides have enough time to float to the surface and form slag), while avoiding energy waste and excessive drop in copper liquid temperature due to excessive time (requiring additional heating to maintain fluidity).

[0063] In some embodiments, in step S3, the titanium-containing material is a copper-titanium master alloy, and the carbon-containing material is high-purity graphite powder.

[0064] The molar ratio of Ti in the titanium-containing material to C in the carbon-containing material is 1:(0.9 to 1.1).

[0065] Limiting the molar ratio of Ti to C to 1:(0.9 to 1.1) ensures that Ti and C react fully, reducing unreacted Ti (avoiding a decrease in copper conductivity) or C (avoiding the formation of graphite inclusions that affect mechanical properties) residues.

[0066] In some embodiments, in step S3, the frequency of the ultrasonic field treatment is 20–25 kHz, and the power is 5–20 kW.

[0067] The ultrasonic parameters are limited to a frequency of 20–25 kHz and a power of 5–20 kW. The frequency of 20–25 kHz is in the high-power ultrasonic band, which can generate a strong "cavitation effect" (forming tiny bubbles in the melt and bursting them instantly, generating local high pressure). This can accelerate the reaction between Ti and C, and also entrain residual gases such as H2 and O2 in the melt into the bubbles and carry them out, achieving efficient degassing. The power of 5–20 kW can be flexibly adjusted according to the volume of copper liquid to ensure that sufficient "acoustic flow effect" (driving violent convection in the melt) is generated to break up TiC nanoparticle agglomerates and aluminum rare earth alloy clumps, achieving uniform dispersion of each component.

[0068] In some embodiments, in step S4, the mass of the aluminum rare earth alloy is 0.1% to 0.3% of the mass of the melt;

[0069] In the aluminum-rare earth alloy, the mass content of aluminum is ≥70%, and the mass content of rare earth elements is 5% to 15%.

[0070] The addition amount of aluminum rare earth alloy is limited to 0.1% to 0.3% of the melt mass. If the addition amount is too low (<0.1%), the deoxidation effect of aluminum will be insufficient, and the grain refinement and interface optimization effects of rare earth will not be obvious. If the addition amount is too high (>0.3%), the excess rare earth will form brittle compounds in the copper matrix, resulting in a decrease in the toughness and conductivity of the copper ingot. 0.1% to 0.3% can ensure that the copper ingot maintains good conductivity while purifying the melt, refining the grains, and improving the interface.

[0071] In some embodiments, in step S5, the alternating magnetic field generated by the electromagnetic crystallizer has a frequency of 50-60 Hz and a magnetic field strength of 0.01-0.05 T.

[0072] The casting temperature is 1000–1100℃.

[0073] The casting temperature is limited to 1000-1100℃. Firstly, it is slightly higher than the melting point of copper (1083℃) to ensure that the nano-reinforced copper-based composite melt maintains good fluidity and can be successfully cast. Secondly, the temperature is not too high (<1100℃) to shorten the solidification time, inhibit excessive growth of copper grains, and reduce solidification shrinkage stress, thus ensuring uniform distribution of the nano-TiC reinforcing phase.

[0074] The electromagnetic parameters are limited to a frequency of 50–60 Hz and a magnetic field strength of 0.01–0.05 T. The frequency of 50–60 Hz is consistent with the frequency of industrial electricity, eliminating the need for additional frequency conversion equipment and reducing equipment modification costs. The magnetic field strength of 0.01–0.05 T can generate suitable electromagnetic pressure, which can both counteract the gravity and surface tension of the copper liquid itself, keeping the copper liquid and the crystallizer wall in "frictionless contact" (eliminating surface defects), and prevent the copper liquid from shrinking excessively in the center due to excessive magnetic field (avoiding internal shrinkage cavities), ultimately obtaining a high-quality ingot with a smooth surface and dense interior.

[0075] In some embodiments, in step S5, the copper ingot is internally dispersed with a nanoscale titanium carbide reinforcing phase, with an average grain size ≤50μm, tensile strength ≥350MPa, and conductivity ≥85%IACS.

[0076] An average grain size of ≤50μm reflects the refinement effect of aluminum rare earth alloys, a tensile strength of ≥350MPa reflects the reinforcing effect of nano-TiC, and a conductivity of ≥85%IACS indicates that the performance enhancement process did not significantly sacrifice the core advantage of copper (conductivity). All three together prove that this process can produce high-strength, high-conductivity high-end copper ingots, meeting the demand for high-performance copper materials in the electronics, power and other fields.

[0077] In summary, the method for preparing copper ingots from scrap copper provided in this application demonstrates significant advantages in process design, impurity removal and purification, performance enhancement, forming quality, and raw material compatibility, breaking through the limitations of traditional scrap copper recycling and smelting in all aspects.

[0078] (1) From the perspective of the process flow, its core advantage lies in the efficient integration of "integration" and "synergy". It breaks the traditional model of smelting and refining being carried out in separate steps. By using oxygen-enriched side blowing technology, the melting, oxidation, slag formation and refining of waste copper are integrated into a single step, which greatly simplifies the process. At the same time, each step follows the logical chain of "pretreatment → purification → enhancement → forming". The preceding steps lay a high-quality foundation for the subsequent steps, and the subsequent steps give full play to the value of the preceding results, forming a synergistic system with interlocking links, avoiding the efficiency loss and performance loss caused by the disconnection of steps in the traditional process.

[0079] (2) In terms of impurity removal and purification, an innovative "step-by-step precision impurity removal" strategy is adopted, which is both thorough and environmentally friendly. In the early stage, a molecular-capturing composite flux is used to specifically capture harmful impurities that are difficult to remove by traditional processes, achieving broad-spectrum and efficient impurity removal. In the later stage, a controllable oxygen potential gas-phase refining technology is used to precisely remove residual specific impurities in a "gas-for-solid" manner. This avoids the solid waste problem caused by traditional solid oxidants and achieves molecular-level selective impurity removal through thermodynamic control, ultimately obtaining high-purity copper liquid, which provides a high-quality matrix for the preparation of high-performance materials.

[0080] (3) In terms of material performance enhancement, it breaks through the bottleneck of traditional waste copper recycling of "only purification, not upgrading" and realizes the leap from ordinary copper to high-performance composite materials. Through ultrasonic-assisted in-situ synthesis technology, nanoscale reinforcing phases are accurately generated in the copper matrix. At the same time, the ultrasonic effect is used to solve the industry problem of easy agglomeration of nanoparticles, ensuring that the reinforcing phase is uniformly dispersed. Combined with the composite modification effect of aluminum rare earth alloy, it not only optimizes the interface bonding between the reinforcing phase and the matrix, but also refines the grains, ultimately enabling the copper ingot to have both high mechanical properties and excellent electrical conductivity, realizing the synergistic improvement of performance.

[0081] (4) In terms of forming quality, relying on electromagnetic soft contact casting technology, the quality of ingots is greatly improved and the cost of subsequent processing is reduced. By using an alternating magnetic field to achieve “soft contact” between the copper liquid and the crystallizer wall, the surface defects commonly found in traditional casting are completely eliminated. At the same time, it promotes uniform solidification of copper liquid, reduces internal component segregation, and makes the surface of the ingot smooth and the interior dense. This near-net-shape high-quality ingot can save a lot of subsequent processing steps such as milling and planing, significantly improving production efficiency and reducing resource consumption.

[0082] (5) In addition, this method has strong adaptability to raw materials and industrial applicability. It has a high tolerance for the cleanliness and composition of waste copper raw materials, and can process mixed waste copper without fine sorting, which greatly reduces the complexity and cost of pretreatment. The core technologies adopted, such as oxygen-enriched side blowing, ultrasonic treatment, and electromagnetic casting, are all derived from mature industrial application scenarios. After innovative adaptation, they have strong stability. The relevant equipment can be provided by domestic enterprises, which facilitates industrial promotion and large-scale production.

[0083] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0084] Example 1

[0085] In this embodiment, mixed brass scrap (mainly from automotive radiators, electrical connectors, etc.) was selected. The initial chemical composition of the scrap by mass fraction is as follows: Cu: 61.5%, Zn: 28.3%, Sn: 3.2%, Pb: 4.1%, Fe: 1.8%, Ni: 0.6%, Al: 0.3%, and other impurities: 0.2%.

[0086] The pretreatment process is as follows: The mixed brass scrap is crushed into pieces with a particle size ≤50mm by a jaw crusher to facilitate subsequent processing; the crushed scrap copper is soaked in an alkaline cleaning agent (5% sodium carbonate solution by mass) at 50℃ for 30 minutes, and then ultrasonically cleaned for 15 minutes to thoroughly remove surface oil and attached dust; the cleaned scrap copper is placed in a hot air drying oven and dried at 120℃ for 2 hours to completely remove moisture; magnetic separation is performed by a high-intensity magnetic separator (magnetic field strength 1.2T) to remove ferromagnetic impurities (mainly Fe and its alloys).

[0087] This embodiment provides a method for preparing copper ingots using scrap copper materials, the method comprising the following steps:

[0088] S11. Take 1000 kg of pretreated scrap copper material and add it together with 150 kg of composite flux (ratio: 50% quartz sand, 15% calcium phosphate, 20% lime, 7.5% fluorite) into an oxygen-enriched side-blown smelting furnace. Inject 95% oxygen-enriched air and natural gas from the tuyeres on the side wall of the furnace, control the molten pool temperature at 1590℃, and process for 45 minutes. In the high-temperature, strong-oxidizing, and violently agitated molten pool environment, organic matter instantly vaporizes and burns; impurities such as Zn, Fe, and Pb are rapidly oxidized, with some ZnO volatilizing and some entering the slag phase; FeO reacts with quartz sand and other materials to form low-melting-point silicate slag; calcium phosphate reacts selectively with Pb to generate stable lead phosphate, which enters the slag phase. After treatment, remove the slag to obtain the first copper liquid, with the following composition: Cu: 94.8%, Zn: 1.4%, Sn: 2.7%, Pb: 0.3%, Fe: 0.1%, and others 0.7%.

[0089] S21. The first copper liquid is transferred to a controlled atmosphere refining furnace, and a N2-H2O mixed gas (20% water vapor, 80% nitrogen) is introduced from the bottom through a permeable brick. The copper liquid temperature is controlled at 1275℃, and the treatment time is 30 minutes. The water vapor selectively oxidizes Sn and residual Zn by regulating the oxygen potential, resulting in the reaction: Sn + 2H2O(g) → SnO2(s) + 2H2(g). The generated SnO2 floats to the top to form a slag layer, while ZnO is mainly volatilized and discharged with the nitrogen. After refining, a second copper liquid is obtained, with the composition improved to: Cu: 98.9%, Sn: 0.2%, Zn: 0.1%, Pb: 0.25%, Fe: 0.05%, and others 0.5%.

[0090] S31. The second copper liquid is heated to 1415℃ under vacuum (0.085MPa), and 4.8kg of Cu-50Ti master alloy (grade CUTi5050, purchased from Beijing Xingrongyuan Technology Co., Ltd.) and 0.86kg of high-purity graphite powder (CAS 7782-42-5) are added. Simultaneously, an ultrasonic device (frequency 22.5kHz, power 12.5kW) is activated for treatment. During this process, the Cu-50Ti master alloy dissolves rapidly, and Ti and C begin to react in situ at high temperature to generate TiC nanoparticles. The cavitation effect of the ultrasonic field removes residual gas from the melt, and the acoustic flow effect promotes uniform mixing of Ti and C, inhibiting initial agglomeration.

[0091] S41. After ultrasonic treatment for 12 minutes, 2.1 kg of aluminum rare earth alloy (0.2% of the melt mass, composition: Al: 75%, Ce: 10%, balance Cu) is added, and ultrasonic treatment continues for 8 minutes. During this process, Ti and C completely react to form a nano-scale TiC reinforcing phase (Ti+C→TiC), and the ultrasonic field ensures its uniform dispersion; Al reacts with residual trace oxygen to further purify the melt, and rare earth elements improve the interfacial bonding force between TiC and the Cu matrix and refine the grains, ultimately yielding a nano-reinforced copper-based composite melt.

[0092] S51. The nano-reinforced copper-based composite melt is introduced into an electromagnetic crystallizer and cast at 1050℃ under the conditions of magnetic field frequency of 55Hz and strength of 0.03T to obtain a copper ingot with a diameter of 200mm.

[0093] The copper ingots obtained in Example 1 were subjected to performance testing, and the results are as follows:

[0094] The chemical composition is as follows: Cu: 97.9%, Ti: 0.95%, C: 0.24%, Ce: 0.18%, Al: 0.15%, impurities <0.55%;

[0095] Microstructure: The nano-TiC reinforced phase (size 50-80 nm) is uniformly dispersed, with an average grain size of 42 μm;

[0096] Mechanical properties: tensile strength 382 MPa, yield strength 295 MPa, elongation 21%;

[0097] Physical properties: Electrical conductivity 87% IACS, thermal conductivity 365 W / (m・K);

[0098] Hardness: HV125.

[0099] Example 2

[0100] In this embodiment, high-lead brass scrap (mainly from scrap valves and pipe fittings) was selected. The initial chemical composition by mass fraction is: Cu: 58.2%, Zn: 25.6%, Pb: 8.5%, Sn: 4.1%, Fe: 2.3%, Ni: 0.7%, and other impurities 0.6%.

[0101] The pretreatment process is the same as in Example 1: crush to a particle size ≤50mm, soak in 5% sodium carbonate solution at 50℃ for 30min + ultrasonic cleaning for 15min, dry at 120℃ for 2h, and remove iron by 1.2T magnetic separation, the Fe content is reduced to 0.6%.

[0102] The preparation method steps are as follows:

[0103] S12. Take 1000 kg of pretreated scrap copper and add it to an oxygen-enriched side-blown smelting furnace along with 160 kg of composite flux (ratio: 45% quartz sand, 20% calcium phosphate, 20% lime, 15% fluorite). Inject 95% oxygen-enriched air and natural gas, control the temperature at 1620℃, and process for 50 min. The composition of the first copper liquid after slag removal is: Cu: 93.5%, Zn: 1.8%, Sn: 3.0%, Pb: 0.2%, Fe: 0.1%, and others 1.4%.

[0104] S22. Transfer to a refining furnace, introduce a N2-H2O mixture (25% water vapor, 75% nitrogen), and treat at 1280℃ for 35 minutes. Second copper liquid composition: Cu: 98.3%, Sn: 0.3%, Zn: 0.1%, Pb: 0.15%, Fe: 0.05%, others 1.1%;

[0105] S32, heated to 1420℃ under vacuum (0.08MPa), 5.0kg of Cu-50Ti master alloy and 0.89kg of high-purity graphite powder were added, and ultrasonic treatment was performed (22kHz, 10kW).

[0106] S42. After sonication for 13 minutes, add 2.2 kg of aluminum rare earth alloy (Al: 70%, La: 12%, balance Cu), and continue sonication for 7 minutes to obtain nano-reinforced composite melt.

[0107] S52, electromagnetic crystallizer casting (frequency 52Hz, strength 0.025T, temperature 1060℃) yields copper ingots with a diameter of 200mm.

[0108] Performance test results:

[0109] Composition: Cu: 97.5%, Ti: 0.98%, C: 0.25%, La: 0.21%, Al: 0.14%, impurities <0.92%;

[0110] Microstructure: TiC particles (60-90 nm) are uniformly distributed, with an average grain size of 45 μm;

[0111] Mechanical properties: tensile strength 375MPa, yield strength 288MPa, elongation 20%;

[0112] Physical properties: Electrical conductivity 86% IACS, thermal conductivity 360 W / (m·K);

[0113] Hardness: HV122.

[0114] Example 3

[0115] In this embodiment, low-zinc scrap copper material (mainly from cable sheaths and motor windings) was selected. The initial chemical composition was: Cu: 72.4%, Zn: 10.3%, Sn: 2.1%, Pb: 3.8%, Fe: 8.5%, Sb: 1.6%, and others: 1.3%.

[0116] The pretreatment process is the same as in Example 1, and the Fe content is reduced to 1.2% after magnetic separation.

[0117] The preparation method steps are as follows:

[0118] S13. Take 1000 kg of pretreated scrap copper and add it to an oxygen-enriched side-blown smelting furnace along with 140 kg of composite flux (55% quartz sand, 12% calcium phosphate, 20% lime, and 13% fluorite). Inject 92% oxygen-enriched air and pulverized coal, and treat at 1560℃ for 40 min. The first copper melt composition is: Cu: 95.2%, Zn: 0.8%, Sn: 1.9%, Pb: 0.3%, Fe: 0.5%, and other components 1.3%.

[0119] S23. Introduce a N2-H2O mixture (15% water vapor, 85% nitrogen) at 1260℃ for 25 minutes. Second copper solution composition: Cu: 99.0%, Sn: 0.2%, Zn: 0.05%, Pb: 0.2%, Fe: 0.3%, others 0.25%;

[0120] S33, heated to 1400℃ under vacuum (0.09MPa), 4.5kg of Cu-50Ti master alloy and 0.81kg of high-purity graphite powder were added, and ultrasonic treatment was performed (24kHz, 15kW).

[0121] S43. After sonication for 11 minutes, add 1.9 kg of aluminum rare earth alloy (Al: 80%, Ce-La mixed rare earth 8%, balance Cu), and continue sonication for 9 minutes.

[0122] S53, electromagnetic casting (frequency 58Hz, strength 0.035T, temperature 1040℃) yields a copper ingot with a diameter of 200mm.

[0123] Performance test results:

[0124] Composition: Cu: 98.1%, Ti: 0.92%, C: 0.23%, RE: 0.15%, Al: 0.16%, impurities <0.44%;

[0125] Microstructure: TiC particles (40-70 nm) are uniformly distributed, with an average grain size of 38 μm;

[0126] Mechanical properties: tensile strength 390MPa, yield strength 302MPa, elongation 22%;

[0127] Physical properties: Electrical conductivity 88% IACS, thermal conductivity 370 W / (m·K);

[0128] Hardness: HV128.

[0129] Example 4

[0130] In this embodiment, electronic waste copper (mainly from waste circuit boards and connectors) is selected. The initial chemical composition is: Cu: 65.7%, Zn: 5.2%, Sn: 6.8%, Pb: 2.3%, Fe: 3.1%, Ag: 0.5%, Si: 1.2%, and other 15.2% (including resin and plastic).

[0131] The pretreatment process is the same as in Example 1, and the Fe content is reduced to 0.8% after magnetic separation.

[0132] The preparation method steps are as follows:

[0133] S14. Take 1000 kg of pretreated scrap copper and add it to an oxygen-enriched side-blown smelting furnace along with 170 kg of composite flux (48% quartz sand, 18% calcium phosphate, 22% lime, and 12% fluorite). Inject 96% oxygen-enriched air and natural gas, and process at 1650℃ for 55 minutes (enhanced organic combustion). First copper melt composition: Cu: 94.0%, Zn: 0.6%, Sn: 3.5%, Pb: 0.2%, Fe: 0.1%, Ag: 0.5%, others 1.1%.

[0134] S24. Introduce a N2-H2O mixture (30% water vapor, 70% nitrogen) at 1290℃ for 40 minutes (to enhance Sn removal). Second copper solution composition: Cu: 98.7%, Sn: 0.1%, Zn: 0.05%, Pb: 0.1%, Ag: 0.5%, others 0.55%;

[0135] S34. Under vacuum (0.075MPa), the temperature is raised to 1430℃, 5.2kg of Cu-50Ti master alloy and 0.93kg of high-purity graphite powder are added, and ultrasonic treatment is performed (25kHz, 18kW).

[0136] S44. After sonication for 14 minutes, add 2.3 kg of aluminum rare earth alloy (Al: 72%, Nd: 10%, balance Cu) and continue sonication for 6 minutes.

[0137] S54, electromagnetic casting (frequency 50Hz, strength 0.04T, temperature 1070℃) yields a copper ingot with a diameter of 200mm.

[0138] Performance test results:

[0139] Composition: Cu: 97.3%, Ti: 1.0%, C: 0.26%, Nd: 0.2%, Al: 0.15%, Ag: 0.5%, impurities <0.59%;

[0140] Microstructure: TiC particles (50-100 nm) are uniformly distributed, with an average grain size of 48 μm;

[0141] Mechanical properties: tensile strength 370MPa, yield strength 280MPa, elongation 19%;

[0142] Physical properties: Electrical conductivity 85% IACS, thermal conductivity 355 W / (m・K);

[0143] Hardness: HV120.

[0144] Example 5

[0145] In this embodiment, mixed scrap copper (50% brass scrap + 50% copper scrap) was selected, and the initial chemical composition was: Cu: 78.3%, Zn: 15.6%, Sn: 1.2%, Pb: 2.1%, Fe: 1.5%, and others: 1.3%.

[0146] The pretreatment process is the same as in Example 1, and the Fe content is reduced to 0.3% after magnetic separation.

[0147] The preparation method steps are as follows:

[0148] S15. Take 1000 kg of pretreated scrap copper and add it to an oxygen-enriched side-blown smelting furnace along with 130 kg of composite flux (60% quartz sand, 10% calcium phosphate, 18% lime, and 12% fluorite). Inject 94% oxygen-enriched air and pulverized coal, and treat at 1580℃ for 35 min. The first copper melt composition is: Cu: 95.5%, Zn: 1.2%, Sn: 1.0%, Pb: 0.3%, Fe: 0.1%, and other components 1.9%.

[0149] S25. Introduce a N2-H2O mixture (20% water vapor, 80% nitrogen) at 1270℃ for 30 minutes. Second copper solution composition: Cu: 99.2%, Sn: 0.1%, Zn: 0.05%, Pb: 0.2%, Fe: 0.05%, others 0.4%;

[0150] S35, under vacuum (0.085MPa), the temperature is raised to 1410℃, 4.6kg of Cu-50Ti master alloy and 0.83kg of high-purity graphite powder are added, and ultrasonic treatment is performed (23kHz, 12kW).

[0151] S45. After sonication for 12 minutes, add 2.0 kg of aluminum rare earth alloy (Al: 78%, Ce: 5%, balance Cu), and continue sonication for 8 minutes.

[0152] S55, electromagnetic casting (frequency 55Hz, strength 0.03T, temperature 1050℃), yields a copper ingot with a diameter of 200mm.

[0153] Performance test results:

[0154] Composition: Cu: 98.3%, Ti: 0.93%, C: 0.23%, Ce: 0.1%, Al: 0.16%, impurities <0.28%;

[0155] Microstructure: TiC particles (40-60 nm) are uniformly distributed, with an average grain size of 35 μm;

[0156] Mechanical properties: tensile strength 395 MPa, yield strength 305 MPa, elongation 23%;

[0157] Physical properties: Electrical conductivity 89% IACS, thermal conductivity 375 W / (m・K);

[0158] Hardness: HV130.

[0159] The performance test results of the copper ingots obtained in Examples 1 to 5 are summarized in Table 1.

[0160] Table 1. Performance of copper ingots from Examples 1 to 5

[0161]

[0162] As shown in Table 1, the copper ingots of Examples 1 to 5 exhibit excellent overall performance:

[0163] Significantly improved purity: Regardless of the difference in copper content of the initial raw materials (58.20% to 78.30%), the copper content of the final product reaches 97.30% to 98.30%, indicating that the process of this application has an outstanding effect on the deep purification of low-quality waste copper and can effectively remove various impurities;

[0164] Excellent microstructure: The size of the nano-TiC reinforcing phase in the copper ingot is controlled between 40 and 100 nm, and the average grain size is ≤50 μm, which reflects the optimization effect of ultrasonic-assisted in-situ synthesis and aluminum rare earth modification on the microstructure.

[0165] Excellent mechanical properties: tensile strength ≥350MPa, yield strength ≥280MPa, elongation ≥19%. The reinforcing effect of nano-TiC and the grain refinement effect together ensure a balance between high strength and good plasticity.

[0166] Outstanding physical properties: electrical conductivity ≥85%IACS and thermal conductivity ≥355W / (m・K), indicating that the core electrical and thermal conductivity advantages of copper were not sacrificed during the performance enhancement process, meeting the stringent requirements of high-end fields for materials;

[0167] Stable hardness: The hardness of all materials reached HV120-130, further confirming the improvement in the mechanical properties of the material.

[0168] Comparative Example 1

[0169] This comparative example is based on the disclosure in Example 1, with the following modifications:

[0170] In step S1, the composite flux does not contain calcium phosphate and consists only of 67.5% quartz sand, 20% lime, and 12.5% ​​fluorite (i.e., the proportions are recalculated after removing calcium phosphate from the original proportions).

[0171] Due to the lack of "molecular trapping" effect of calcium phosphate, the smelting process could not effectively target and remove lead (Pb). The Pb content in the first copper melt was as high as 3.8%, far exceeding the 0.3% in Example 1. Subsequent gas-phase refining had limited effect on Pb removal, resulting in a final Pb content of 0.82% in the copper ingot. The high Pb content severely segregated at the grain boundaries, leading to increased brittleness and a significant decrease in overall performance: tensile strength was 284 MPa, and conductivity was 78% IACS. This comparative example demonstrates the crucial role of calcium phosphate in deep lead removal and improving material properties.

[0172] Comparative Example 2

[0173] This comparative example is based on the disclosure in Example 1, with the following modifications:

[0174] Step S2 (vapor phase transport refining) is omitted. The first copper liquid obtained in S1 is directly processed into step S3.

[0175] Because a vapor-phase refining step targeting Sn and residual Zn was missing, up to 2.7% Sn in the first copper melt directly entered subsequent processes. Sn significantly degraded the conductivity of the copper matrix and affected the interfacial bonding between the in-situ generated TiC reinforcing phase and the matrix. The final product contained 0.95% Sn, with the following properties: tensile strength of 321 MPa and conductivity of 72% IACS. This comparative example demonstrates that vapor-phase transport refining is crucial for removing specific impurities and obtaining a high-purity copper matrix, a prerequisite for the successful preparation of high-performance composite materials.

[0176] Comparative Example 3

[0177] This comparative example is based on the disclosure in Example 1, with the following modifications:

[0178] In steps S3 and S4, no ultrasonic field treatment is applied; only mechanical stirring is performed.

[0179] In the absence of ultrasonic cavitation and acoustic flow effects, the TiC nanoparticles generated in situ rapidly and severely agglomerated, forming micron-sized clusters accompanied by compositional segregation. These clusters became crack initiation sites after casting, severely impairing the material's density and mechanical properties. The final product exhibited a poor microstructure, with a tensile strength of only 316 MPa, an elongation plummeting to 8%, and a conductivity (81% IACS) lower than in Example 1 due to increased interface defects. This comparative example demonstrates that ultrasonic fields are an indispensable key means for suppressing nanoparticle agglomeration and achieving their uniform dispersion.

[0180] Comparative Example 4

[0181] This comparative example is based on the disclosure in Example 1, with the following modifications:

[0182] In step S3, aluminum rare earth alloy, titanium-containing material, and carbon-containing material are added simultaneously, and ultrasonic field treatment is performed.

[0183] Rare earth elements (Ce) in aluminum-rare earth alloys are chemically extremely reactive. In high-temperature melts, they preferentially react with elements such as Ti and C and oxygen, and are largely oxidized to form rare earth oxide slag, which is then completely consumed. Therefore, rare earth elements fail to purify grain boundaries and improve the TiC / copper interface bonding. The final product has extremely low rare earth content, coarsened grains, and weak bonding between the TiC reinforcing phase and the matrix, resulting in limited performance improvement: tensile strength of 342 MPa and conductivity of 84% IACS. This comparative example demonstrates that the specific timing design of "delayed addition of aluminum rare earths" is crucial for protecting its modified properties and achieving synergistic reinforcement effects.

[0184] Comparative Example 5

[0185] This comparative example is based on the disclosure in Example 1, with the following modifications:

[0186] The electromagnetic field in step S5 is omitted, and a common metal crystallizer is used for casting.

[0187] In traditional casting, molten copper comes into direct contact with the crystallizer wall, and rapid, uneven cooling leads to defects such as cold shuts and oscillation marks on the ingot surface, as well as coarse grains and significant compositional segregation. The nano-TiC reinforcing phase is pushed to the grain boundaries and enriched during solidification, failing to provide the desired pinning reinforcement. The final ingot requires extensive milling and multiple hot working passes before use, resulting in low yield and inconsistent properties: tensile strength 356 MPa, conductivity 85% IACS. This comparative example demonstrates that electromagnetic soft-contact casting is essential for obtaining high-quality ingots with uniform internal structure and smooth surfaces, thus fully preserving the excellent material properties imparted by previous processes.

[0188] Comparative Example 6

[0189] This comparative example is based on the disclosure in Example 1, with the following modifications:

[0190] The "in-situ synthesis" logic in steps S31 to S41 is removed. Instead, nano-TiC particles (50-80 nm in diameter and 0.86 kg in mass) that are equivalent to the theoretical reaction amount of Ti and C in Example 1 are directly added to the second copper liquid. The ultrasonic device is not activated, and the particles are dispersed by natural convection of the melt. The remaining steps and parameters are the same as in Example 1.

[0191] Due to their extremely high surface energy, nano-TiC particles easily aggregate through van der Waals forces in the absence of external dispersion. The natural convection of the melt has limited dispersion capabilities and cannot break up the existing agglomerates. Ultimately, nano-TiC particles form numerous agglomerates with sizes ranging from 2 to 5 μm in the copper matrix, not only losing the size effect of the nanoscale reinforcing phase but also becoming stress concentration points and crack initiation sites within the material. Simultaneously, without ultrasonic treatment, the melt grains are difficult to refine (average grain size reaches 60 μm). Therefore, the overall performance of the product is significantly reduced: tensile strength is only 280 MPa (a 26.7% decrease compared to Example 1), elongation drops to 12%, conductivity drops to 80% IACS, and hardness is only HV98. This comparative example demonstrates the necessity of "ultrasound-assisted in-situ synthesis" technology. Generating a reinforcing phase through in-situ reaction can reduce the tendency to agglomerate from the source. Combined with the cavitation and acoustic flow effects of ultrasound, it can completely solve the problem of nanoparticle dispersion and is the core of improving the performance of copper materials.

[0192] Comparative Example 7

[0193] This comparative example is based on the disclosure in Example 1, with the following modifications:

[0194] In step S31, aluminum rare earth alloy, Cu-50Ti master alloy, and high-purity graphite powder are added to the melt simultaneously, and then ultrasonic field treatment is started. That is, the timing design of "adding aluminum rare earth alloy after ultrasonic treatment for 12 minutes" is cancelled. The remaining steps and parameters are the same as in Example 1.

[0195] Rare earth elements (Ce) in aluminum-rare earth alloys are chemically highly reactive, while the melt in the initial stage of step S31 still contains a significant amount of oxygen and unreacted Ti. When aluminum-rare earth alloys are added at this point, the rare earth elements preferentially react with oxygen to form rare earth oxide slag, and also combine with Ti to form non-functional compounds, resulting in a large consumption of rare earth elements (the Ce content in the final product is only 0.05%, a decrease of 72.2% compared to Example 1). This prevents them from fulfilling their functions of purifying grain boundaries, improving the interface between TiC and the copper matrix, and refining grains. Ultimately, the TiC particles in the product are unevenly dispersed, with the average grain size coarsening to 58 μm (an increase of 38.1% compared to Example 1), and the overall performance significantly declines: tensile strength 335 MPa (a decrease of 12.3% compared to Example 1), elongation 17%, conductivity 82% IACS, and hardness HV110. This comparative example demonstrates the key value of the "delayed addition of aluminum rare earth elements" timing design. By avoiding the presence of highly active impurities in the melt, the functionality of rare earth elements can be effectively protected, allowing them to synergize with the ultrasonic field and TiC-reinforced phase, thus ensuring the improvement of material performance.

[0196] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0197] Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0198] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for producing a copper ingot using scrap copper material, characterized by, The method comprises the following steps: S1, adding the pretreated waste copper material and a composite flux into an oxygen-enriched side-blown smelting furnace, and spraying oxygen and fuel from tuyeres on the side wall of the furnace body of the oxygen-enriched side-blown smelting furnace to simultaneously melt, oxidize and slag-refine the waste copper material to obtain a first copper liquid; the composite flux is composed of quartz sand, calcium phosphate, lime and fluorite; the mass of the quartz sand accounts for 40-60% of the total mass of the composite flux, the mass of the calcium phosphate accounts for 10-20% of the total mass of the composite flux, the mass of the lime accounts for 15-25% of the total mass of the composite flux, and the mass of the fluorite accounts for 5-10% of the total mass of the composite flux; S2, transferring the first copper liquid into a refining furnace, and introducing a mixed gas composed of water vapor and nitrogen from the bottom of the refining furnace to remove tin and zinc impurities in the first copper liquid to obtain a second copper liquid; the volume of the water vapor accounts for 10-30% of the total volume of the mixed gas, and the volume of the nitrogen accounts for 70-90% of the total volume of the mixed gas; the temperature for introducing the mixed gas from the bottom of the refining furnace is 1250-1300 DEG C, and the time is 20-40 min; S3, under vacuum conditions, heating the second copper liquid to 1380-1450 DEG C, adding a titanium-containing substance and a carbon-containing substance into the melt, and simultaneously performing ultrasonic field treatment on the melt; the frequency of the ultrasonic field treatment is 20-25 kHz, and the power is 5-20 kW; S4, when the time of the ultrasonic field treatment reaches 10-15 min, adding an aluminum-rare earth alloy into the melt, and continuing the ultrasonic field treatment for 5-10 min to generate nanoscale titanium carbide reinforcing phases in the melt through in-situ reaction to obtain a nanoscale reinforced copper-based composite melt; S5, introducing the nanoscale reinforced copper-based composite melt into an electromagnetic crystallizer to perform casting, and performing solidification under electromagnetic pressure generated by an alternating magnetic field to obtain a copper ingot; the frequency of the alternating magnetic field generated by the electromagnetic crystallizer is 50-60 Hz, and the magnetic field strength is 0.01-0.05 T; the temperature of the casting is 1000-1100 DEG C.

2. The method of claim 1, wherein the copper ingot is prepared using the waste copper material. In step S1, the temperature for the melting, oxidation and slag-refining is 1500-1680 DEG C, and the time is 30-60 min.

3. The method of claim 1, wherein the copper ingot is prepared by using the waste copper material. In step S1, the oxygen is oxygen-enriched air with a volume concentration of > 90%, and the fuel is natural gas or coal powder.

4. The method of claim 1, wherein the copper ingot is prepared by using the waste copper material. In step S3, the titanium-containing substance is a copper-titanium intermediate alloy, and the carbon-containing substance is high-purity graphite powder; The molar ratio of Ti elements in the titanium-containing substance to C elements in the carbon-containing substance is 1:(0.9-1.1).

5. The method of claim 1, wherein the copper ingot is prepared by using the waste copper material. In step S4, the mass of the aluminum-rare earth alloy is 0.1%-0.3% of the mass of the melt; In the aluminum-rare earth alloy, the mass content of aluminum is ≥ 70%, and the mass content of rare earth elements is 5%-15%.

6. The method of claim 1, wherein the copper ingot is prepared by using the waste copper material. In step S5, the copper ingot has nanoscale titanium carbide reinforcing phases dispersedly distributed in the interior, the average grain size is ≤ 50 μm, the tensile strength is ≥ 350 MPa, and the electrical conductivity is ≥ 85% IACS.

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