Method for preparing copper-based friction material from copper-containing electronic scrap

Abstract

This invention relates to a method for preparing copper-based friction materials from copper-containing electronic waste, belonging to the field of electronic waste resource utilization technology. The invention involves uniformly mixing copper-containing electronic waste with copper-containing solid waste to obtain a mixture. This mixture is added to a smelting pool and heated to melt. Oxygen-enriched gas is introduced for oxidative smelting to obtain an oxidized melt. A reducing agent is added to the oxidized melt, and a protective gas is introduced for stirring and heat preservation for reduction smelting. Copper-rich alloy and slag are separated by sedimentation. The copper-rich alloy is powdered to obtain copper alloy powder. The copper alloy powder and friction components are uniformly mixed and pressed into a billet. The billet is sintered to obtain the copper-based friction material. The coefficient of friction of the copper-based friction material is 0.25~0.60, and the wear rate is ≤2.5×10⁻⁶. ‑ 7 cm 3 / J, with a hardness of 40~80HB. This invention achieves the synergistic treatment of copper-containing electronic waste and copper-containing solid waste through high-temperature smelting, efficiently recovering valuable metals, and directly preparing copper-based friction materials from the copper-rich alloy produced by smelting.

Description

Technical Field

[0001] This invention relates to a method for preparing copper-based friction materials from copper-containing electronic waste, belonging to the field of electronic waste resource utilization technology. Background Technology

[0002] Electronic waste has a complex composition, typically consisting of 40% metals, 30% ceramics, and 30% organic polymers and fibers. It is rich in metals such as copper, iron, tin, nickel, lead, and zinc, and also contains rare and precious metals like silver, gold, and platinum. Copper-based powder metallurgy materials are widely used in high-speed trains and engineering machinery due to their stable coefficient of friction, excellent wear and heat resistance, good environmental adaptability, and minimal damage to brake discs. Traditionally, copper-based powder metallurgy materials are made by mixing, pressing, and sintering pure metal powders (such as electrolytic copper powder, atomized tin powder, and reduced iron powder), resulting in high raw material costs. If the metal components (copper, tin, lead, zinc, iron, etc.) in copper-containing electronic waste can be smelted to obtain copper-rich alloys, and then appropriately adjusted in composition before being directly used as powder metallurgy raw materials, the recycling of metal resources from electronic waste can be achieved, resulting in significant economic benefits.

[0003] In the prior art, patent CN110453076A discloses a method for recovering and preparing recycled copper alloys from waste circuit board metal-rich aggregates, which uses mechanical processing technology (crushing, sorting, etc.) to recover the metal-rich aggregates. However, this method can only process a small range of waste circuit boards, has significant limitations, a lengthy process, and cannot solve the problem of disposing of large amounts of non-metallic resin powder after metal recovery. Furthermore, patent CN110551897B discloses a mechanical-physical process for processing waste circuit boards to prepare pure copper powder, which obtains pure copper powder through more than ten steps including crushing, air separation, magnetic separation, ball milling, sieving, shaking, and acid leaching, and explicitly states that "no metallurgical process is required." This process pursues high-purity copper powder, removing elements such as tin and iron as impurities, resulting in a complex process, high acid consumption, and secondary pollution from waste acid. In addition to waste circuit boards, copper-containing sludge, copper smelting slag, and copper blowing slag are also important copper-containing secondary resources. These materials contain valuable metals such as copper, nickel, zinc, and iron, but existing technologies mostly process them separately or simply mix and smelt them, failing to fully leverage the advantages of co-processing copper-containing solid waste from multiple sources, and even less directly guiding their smelting products towards the preparation of high-value-added copper-based friction materials.

[0004] Therefore, developing a method that is short in process, low in cost, free from secondary pollution, and capable of co-processing copper-containing solid waste from multiple sources and directly converting valuable metals into high-value-added copper-based friction materials is of great practical significance and has broad application prospects. Summary of the Invention

[0005] To address the shortcomings and defects of existing technologies, such as long process, need for physical sorting and pretreatment, need for acid leaching to remove impurities, the product being only pure copper powder that cannot be directly used for friction material preparation, and inability to co-process copper-containing solid waste from multiple sources, this invention proposes a method for preparing copper-based friction materials from copper-containing electronic waste. This method achieves co-processing of copper-containing electronic waste and copper-containing solid waste through high-temperature smelting, efficiently recovering valuable metals, and directly preparing copper-based friction materials from the copper-rich alloy produced by smelting.

[0006] A method for preparing copper-based friction materials from copper-containing electronic waste, the specific steps of which are as follows: (1) Mix copper-containing electronic waste and copper-containing solid waste evenly to obtain a mixture. Add the mixture to a smelting pool and heat to melt. Introduce oxygen-enriched gas for oxidative smelting to obtain an oxidative smelting melt. The copper-containing solid waste is one or more of copper smelting slag, copper blowing slag, and copper-containing sludge. It serves as both a slag-forming agent to adjust the composition of the smelting system and a secondary copper resource to provide valuable metals. (2) Add a reducing agent to the oxidative smelting melt, introduce a protective gas for stirring and heat preservation smelting, and separate copper-rich alloys and slag by sedimentation. (3) The copper-rich alloy is pulverized to obtain copper alloy powder. The copper alloy powder and friction components are mixed evenly and pressed into a blank. The blank is sintered to obtain copper-based friction material. The friction components are one or more of graphite, silicon dioxide, silicon carbide and barium sulfate. The copper-rich alloy is not subjected to additional impurity removal treatment before pulverization and does not need to be added separately with tin powder and iron powder.

[0007] By mass percentage, the copper-containing electronic waste contains Cu 10-30%, Sn 2-10%, Pb 1-2%, Ni 1-5%, Ca 5-12%, Al 2-6%, Si 12-20%, and Br 1-5%.

[0008] Preferably, in step (1), the oxygen concentration in the oxygen-enriched gas is 30~60 vol.%, and the oxygen flow rate in the oxygen-enriched gas is 0.5~2 L / min.

[0009] Preferably, the oxidation smelting temperature in step (1) is 1200~1400℃ and the smelting time is 1~2h; the mass ratio of Fe to SiO2 during the oxidation smelting process is 1.0~1.4:1.

[0010] Preferably, the reducing agent in step (2) is one or more of anthracite, biochar, and biomass oil; the amount of reducing agent added is 2.5 to 10% of the mass of the copper-rich alloy.

[0011] Preferably, the temperature of the heat preservation reduction smelting in step (2) is 1200~1400℃, and the smelting time is 1~2h.

[0012] The copper-rich alloy in step (2) contains 70-90% Cu, 5-10% Sn, 1-5% Fe, 1-3% Pb, and 0.5-2% Zn by mass percentage.

[0013] Preferably, in step (3), the particle size of the copper alloy powder is 10~60μm, and the mass ratio of the copper alloy powder to the friction component is 6~10:1.

[0014] Preferably, the pressure for pressing the blank in step (3) is 200~600MPa, and the holding time is 15~30s.

[0015] Preferably, the sintering method in step (3) is vacuum hot pressing sintering or discharge plasma sintering, the sintering temperature is 700~900℃, the holding time is 30~120min, and the sintering pressure is 10~50MPa.

[0016] Preferably, the coefficient of friction of the copper-based friction material is 0.25~0.60, and the wear rate is ≤2.5×10⁻⁶. -7 cm 3 / J, hardness is 40~80HB.

[0017] The mechanism of preparing copper-based friction materials from copper-containing electronic waste in this invention: This invention utilizes the complementary composition and thermochemical synergy between copper-containing electronic waste (waste circuit boards) and multi-source copper-containing solid waste (copper sludge, copper smelting slag, copper blowing slag, etc.) to achieve in-situ alloying of valuable metals and directional separation of impurities through a two-stage oxidation-reduction smelting process, ultimately directly obtaining alloy powder suitable for copper-based friction materials.

[0018] Unlike the traditional physical mixing route of "pure copper powder + added Sn and Fe powder", this invention adopts a chemical metallurgical route: the metal elements are uniformly mixed in the melt at the atomic scale to form a thermodynamically stable solid solution or compound phase, rather than a simple mechanical mixture. This atomic-level uniformity is the microscopic basis for the stable friction coefficient of copper-based friction materials.

[0019] (1) Synergistic mechanism of raw material components In copper-containing electronic waste, Cu serves as the base metal source, Sn is used to form Cu-Sn solid solutions for solid solution strengthening, Fe comes from component leads and solder joints, acting as a dispersion strengthening element to form an iron-rich granular phase, and Al comes from electrolytic capacitors and heat sinks, serving both as a heat-generating component and forming Cu-Al intermetallic compounds. Epoxy resin and other organic materials act as fuels, providing smelting heat. HBr released from copper-containing electronic waste reacts with CaO and FeO / Fe3O4, entering the slag phase. Waste circuit boards simultaneously provide a metal source, a heat source, and a reducing agent precursor.

[0020] In the multi-source copper-containing solid waste, copper-containing sludge replenishes the copper source and provides CaO as a bromine-fixing agent. The FeO·SiO2 system of copper smelting slag is a natural slag-forming agent. Copper blowing slag has a high copper content and a high FeO content, which can be used to adjust the Fe / SiO2 ratio. These solid wastes are not simply waste, but mineral raw materials with controllable composition. Among them, FeO combines with SiO2 to form low-melting-point fir olivine, which adjusts the slag viscosity and melting point. CaO and FeO / Fe3O4 convert HBr released from copper-containing electronic waste into stable CaBr2 and FeBr2, which enter the slag phase and prevent dioxin formation. The exothermic oxidation of sulfides in copper slag and copper-containing sludge replenishes the smelting heat.

[0021] The core logic behind this synergistic approach is that waste circuit boards have a high organic content and require a large amount of oxygen, while the oxidation of sulfides in multi-source copper-containing solid waste requires relatively less oxygen. Mixing the two achieves a balance between elemental supply and demand, as well as thermochemical coupling. Specifically, the combination of FeO and SiO2 in the multi-source solid waste to form fir olivine increases the Fe / SiO2 ratio to an ideal range, significantly reducing slag viscosity and metal loss. Valuable metals such as Ni and Zn in copper-containing sludge and copper slag are simultaneously enriched. Ni and Cu are infinitely miscible, forming a (Cu,Ni) solid solution, while Zn partially enters the alloy phase, forming a Cu-Zn solid solution. The synergistic exothermic processes of organic combustion, Al oxidation, and sulfide oxidation in the waste circuit boards achieve self-heating or quasi-self-heating smelting, avoiding furnace temperature runaway or thermal shock.

[0022] (2) Mechanism analysis of process steps ① Oxidation smelting stage The core chemical reactions in the oxidation smelting stage include: combustion of organic matter, which provides approximately 30-50% of the smelting heat; ; The oxidation of sulfides releases heat and generates SO2, which enters the flue gas. ; ; ; The oxidation of metallic aluminum is a violently exothermic process, making it an important auxiliary heat source. ; Iron oxides combine with SiO2 to form a low-melting-point, low-viscosity fir olivine slag phase; ; Bromine fixation: HBr reacts with CaO in the furnace gas to form stable CaBr2, which is fixed in the slag phase, effectively inhibiting the formation of dioxin precursors.

[0023] ; ; After this stage, organic matter, sulfides, and Al are basically completely oxidized. Cu mainly exists in the melt as CuO / Cu2O, with some existing as metallic copper. Sn and Fe are partially oxidized into the slag phase and partially retained in the metallic phase. The slag is a low-viscosity, low-melting-point fir olivine slag with good fluidity, which is beneficial for subsequent slag-metal separation.

[0024] ② Reduction smelting stage A carbonaceous reducing agent is added to the oxidizing melt, and a protective gas is introduced while stirring. The core chemical reactions include: (i) Reduction of metal oxides: ; ; ; ; CuO / Cu2O is preferentially reduced to metallic Cu, and some Fe is reduced into the alloy phase. (ii) Reduction and alloying of tin and lead: ; ; ; ; After Sn and Ni are reduced, they form (Cu,Sn) and (Cu,Ni) solid solutions with Cu. After lead is reduced, it further volatilizes or dissolves into the alloy. ZnO is reduced by C to generate Zn vapor (boiling point 907℃), some of which escapes into the flue gas and some dissolves in Cu to form Cu-Zn solid solutions.

[0025] ③ In-situ alloying mechanism Traditional copper-based friction material preparation processes employ a physical mixing → pressing → sintering route involving "pure copper powder + added Sn powder + added Fe powder," which suffers from inherent defects such as uneven composition, Sn low-melting-point segregation, and Fe agglomeration. The in-situ alloying mechanism employed in this invention is as follows: (i) Uniform mixing at the atomic scale: At the melting temperature, Cu, Sn, and Fe are completely miscible. Sn and Fe are uniformly distributed in the Cu melt as individual atoms, forming a truly homogeneous solution, which determines the compositional consistency of the alloy powder from the source. (ii) Phase formation during solidification: During the cooling and solidification process, the copper-rich alloy melt undergoes the following phase transformations in sequence: First, the ε(Cu3Sn) phase precipitates along the grain boundaries, forming a submicroscopic Sn-rich phase uniformly distributed at the grain boundaries. Subsequently, the α-Cu solid solution grows in a dendritic morphology, and Sn and Fe atoms enter the Cu lattice to form a substitutional solid solution. The remaining liquid phase undergoes a eutectoid transformation, making the microstructure more homogeneous. At the same time, as the temperature decreases, the solubility of Fe in Cu decreases, and it precipitates uniformly in the α-Cu matrix as nano-sized particles. Finally, a three-phase homogeneous composite structure is obtained, consisting of an α-Cu solid solution matrix, ultrafine ε(Cu3Sn) phase distributed at the grain boundaries, and nano-Fe particles dispersed within the grains. (iii) Structure retention after direct powdering: The powder obtained by atomizing a uniform alloy ingot maintains the same uniform structure for each particle, which is fundamentally different from the heterogeneous structure of physically mixed powder.

[0026] ④ Mechanism of subsequent forming stages Copper-rich alloy ingots are rapidly solidified through atomization powdering, preserving and refining the uniformly distributed structure in the smelted microstructure and suppressing macroscopic segregation of Sn. Copper alloy powder is physically mixed with friction components (graphite, SiO2, SiC, etc.) and pressed into billets, which are then sintered under a protective atmosphere. During sintering, sintering necks form between Cu alloy particles, connecting them to form a continuous matrix. The uniformly distributed ε-phase and Fe phase do not undergo significant coarsening at the sintering temperature, and the friction components are encapsulated or embedded within the Cu matrix to form a friction layer. The final product achieves an ideal microstructure consisting of a continuous Cu alloy matrix, uniformly distributed fine ε-phase, nano-Fe dispersed particles, and friction component particles.

[0027] The beneficial effects of this invention are: (1) This invention utilizes Sn and Fe from waste circuit boards as alloy strengthening components, and the Sn and Fe in the copper-rich alloy obtained by smelting are in an in-situ alloyed state. Compared with the existing technology that uses pure copper powder with Sn and Fe powder, the alloy elements of this invention are more uniformly distributed, the microstructure is more consistent, and the friction coefficient is more stable. At the same time, this invention does not require physical sorting and acid leaching to remove impurities, avoiding the loss of fine metal particles, lengthy process and waste acid pollution problems, significantly improving the recovery rate of valuable metals and simplifying the process. (2) This invention co-melts copper-containing solid wastes from multiple sources, such as copper sludge, copper smelting slag, and copper blowing slag, with waste circuit boards. The multi-source copper-containing solid wastes not only act as slag-forming agents to adjust the Fe / SiO2 ratio and slag viscosity of the smelting system, but also enrich the valuable metals (copper, nickel, zinc, etc.) in the copper-rich alloy during the smelting process, realizing the synergistic resource utilization of multi-source copper-containing solid wastes, broadening the source of raw materials, and improving the processing capacity. (3) By adjusting the ratio of copper-containing electronic waste and copper-containing solid waste from multiple sources and the smelting conditions, the present invention can make the content of Cu, Sn and Fe in copper-rich alloys adjustable within a wide range, so that the alloy composition can be adjusted according to different requirements. (4) In the smelting process, the organic components in the copper-containing electronic waste are fully burned, which can provide some energy for the furnace; the oxidation of metallic aluminum in electronic waste and sulfides in multi-source copper-containing solid waste can release a large amount of heat, realizing low-carbon self-heating smelting and reducing external fuel consumption; at the same time, the copper-rich alloy produced by the smelting is directly used to prepare copper-based friction materials, saving the purchase cost of pure metal powder in the traditional process, reducing the overall cost by 30%-50%, and has good prospects for industrial application. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of the present invention; Figure 2 The bar chart shows the average friction coefficient and wear rate of the copper-based friction materials in Examples 1 and 2. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0030] Example 1: By mass percentage, the copper-containing electronic waste in this example contains Cu 20%, Sn 5%, Pb 2%, Ni 2%, Ca 7%, Al 4%, Si 15%, and Br 2%. A method for preparing copper-based friction materials from copper-containing electronic waste, the specific steps of which are as follows: (1) Mix copper-containing electronic waste and copper-containing solid waste (copper smelting slag) evenly to obtain a mixture. Add the mixture to a smelting pool and heat to melt. Introduce oxygen-enriched gas with an oxygen concentration of 40% (oxygen flow rate of 1.0 L / min) and oxidize and smelt at 1300℃ for 1.5 h to obtain an oxidized smelting melt. During the oxidized smelting process, control the mass ratio of Fe to SiO2 in the melt to be 1.2:1. The copper-containing solid waste (copper smelting slag) serves both as a slag-forming agent to adjust the composition of the smelting system and as a secondary copper resource to provide valuable metals. (2) A reducing agent (biochar) is added to the oxidative smelting melt, a protective gas (nitrogen) is introduced and stirred, and the smelting is carried out at a temperature of 1300℃ for 1.5h. The copper-rich alloy and slag are separated by sedimentation. By mass percentage, the copper-rich alloy in this embodiment contains 70% Cu, 5% Sn, 1% Fe, 1% Pb, and 1% Zn. (3) Copper-rich alloy is atomized to obtain copper alloy powder with a particle size of less than 200 mesh. The copper alloy powder and friction components (graphite, SiO2 and SiC) are mixed evenly and pressed into a blank at a pressure of 400 MPa for 20 s. The blank is heated to the discharge plasma sintering temperature of 750℃, 800℃, 850℃ and 900℃ respectively and sintered by discharge plasma at a pressure of 20 MPa for 60 min. It is then cooled to room temperature in the furnace to obtain copper-based friction material. The copper-based friction material samples with sintering temperatures of 750℃, 800℃, 850℃ and 900℃ are respectively recorded as samples A1, A2, A3 and A4. The mass ratio of copper alloy powder, graphite, SiO2 and SiC is 45:2:2:1. In this embodiment, the average kinetic friction coefficients of the copper-based friction materials A1, A2, A3, and A4 are 0.34, 0.46, 0.54, and 0.41, respectively, and their wear rates are 1.92 × 10⁻⁶. -7 cm 3 / J, 1.66×10 -7 cm 3 / J, 1.27×10 -7 cm 3 / J, 1.89×10 -7 cm 3 / J (see Figure 2 The hardnesses are 40HB, 65HB, 72HB, and 55HB, respectively, and the compressive strengths are 170MPa, 230MPa, 290MPa, and 200MPa, respectively.

[0031] Example 2: By mass percentage, the copper-containing electronic waste in this example contains 30% Cu, 10% Sn, 5% Pb, 5% Ni, 12% Ca, 5% Al, 20% Si, and 5% Br; A method for preparing copper-based friction materials from copper-containing electronic waste, the specific steps of which are as follows: (1) Mix copper-containing electronic waste and copper-containing solid waste (copper smelting slag) evenly to obtain a mixture. Add the mixture to a smelting pool and heat to melt. Introduce oxygen-enriched gas with an oxygen concentration of 60% (oxygen flow rate of 2.0 L / min) and oxidize and smelt at 1400℃ for 1 hour to obtain an oxidized smelting melt. During the oxidized smelting process, control the mass ratio of Fe to SiO2 in the melt to be 1.4:1. The copper-containing solid waste (copper smelting slag) serves both as a slag-forming agent to adjust the composition of the smelting system and as a secondary copper resource to provide valuable metals. (2) A reducing agent (biomass oil) is added to the oxidative smelting melt, a protective gas (nitrogen) is introduced for stirring, and the melt is kept at 1400℃ for 2 hours for reduction smelting. The copper-rich alloy and slag are separated by sedimentation. By mass percentage, the copper-rich alloy in this embodiment contains 88% Cu, 10% Sn, 1% Fe, 0.5% Pb, and 0.5% Zn. (3) Copper-rich alloy is atomized to obtain copper alloy powder with a particle size of less than 200 mesh. The copper alloy powder and friction components (graphite, SiO2 and SiC) are mixed evenly and pressed into a blank at a pressure of 500 MPa for 30 s. The blank is heated to the vacuum hot pressing sintering temperature of 750℃, 800℃, 850℃ and 900℃ respectively and sintered under vacuum hot pressing at a pressure of 40 MPa for 120 min. It is then cooled to room temperature in the furnace to obtain copper-based friction material. The copper-based friction material samples with sintering temperatures of 750℃, 800℃, 850℃ and 900℃ are recorded as samples B1, B2, B3 and B4 respectively. The mass ratio of copper alloy powder, graphite, SiO2 and SiC is 91:3:3:3. In this embodiment, the average kinetic friction coefficients of copper-based friction materials B1, B2, B3, and B4 are 0.37, 0.43, 0.59, and 0.43, respectively, and their wear rates are 1.86 × 10⁻⁶. -7 cm 3 / J, 1.55×10 -7 cm 3 / J、1.16×10 -7 cm 3 / J, 1.91×10 -7 cm 3 / J (see Figure 2 The hardnesses are 50HB, 66HB, 78HB, and 60HB, respectively, and the compressive strengths are 200MPa, 260MPa, 310MPa, and 220MPa, respectively.

[0032] Example 3: By mass percentage, the copper-containing electronic waste in this example contains 10% Cu, 2% Sn, 1% Pb, 1% Ni, 5% Ca, 2% Al, 12% Si, and 1% Br. A method for preparing copper-based friction materials from copper-containing electronic waste, the specific steps of which are as follows: (1) Mix copper-containing electronic waste and copper-containing solid waste (copper-containing sludge) evenly to obtain a mixture. Add the mixture to a smelting pool and heat to melt. Introduce oxygen-enriched gas with an oxygen concentration of 30% (oxygen flow rate of 0.5 L / min) and oxidize and smelt at 1250℃ for 2 hours to obtain an oxidized smelted melt. During the oxidized smelting process, control the mass ratio of Fe to SiO2 in the melt to be 1.0:1. The copper-containing solid waste (copper-containing sludge) serves both as a slag-forming agent to adjust the composition of the smelting system and as a secondary copper resource to provide valuable metals. (2) A reducing agent (anthracite) is added to the oxidative smelting melt, a protective gas (argon) is introduced for stirring, and the melt is kept at 1250℃ for 1 hour for reduction smelting. The copper-rich alloy and slag are separated by sedimentation. By mass percentage, the copper-rich alloy in this embodiment contains 70% Cu, 5% Sn, 1% Fe, 1% Pb, and 1% Zn. (3) Copper-rich alloy is atomized to obtain copper alloy powder with a particle size of less than 200 mesh. The copper alloy powder and friction components (graphite, silicon carbide, barium sulfate) are mixed evenly and pressed into a blank at a pressure of 200 MPa for 15 s. The blank is heated to the vacuum hot pressing sintering temperature of 750℃, 800℃, 850℃, and 900℃ respectively and sintered under vacuum hot pressing at a pressure of 10 MPa for 30 min. It is then cooled to room temperature in the furnace to obtain copper-based friction material. The copper-based friction material samples with sintering temperatures of 750℃, 800℃, 850℃, and 900℃ are respectively recorded as samples C1, C2, C3, and C4. The mass ratio of copper alloy powder, graphite, silicon carbide and barium sulfate is 85:5:5:5. In this embodiment, the average kinetic friction coefficients of the copper-based friction materials C1, C2, C3, and C4 are 0.28, 0.37, 0.46, and 0.41, respectively, and the wear rates are 2.01 × 10⁻⁶. -7 cm 3 / J, 1.77×10 -7 cm 3 / J, 1.35×10 -7 cm 3 / J、2.10×10 -7 cm 3 The hardness values ​​were 45HB, 58HB, 68HB, and 50HB, respectively, and the compressive strengths were 140MPa, 185MPa, 240MPa, and 160MPa, respectively.

[0033] Comparative Example 1: A copper-based friction material was prepared using commercially available pure metal powder as raw material through a traditional powder metallurgy method. The specific steps included: (1) Weigh the raw material powders by mass percentage: 78% electrolytic copper powder (purity ≥99.5%), 8% tin powder (purity ≥99%), 2% iron powder (purity ≥98%), 2% lead powder, 1% zinc powder, and 9% friction components (graphite, SiO2, SiC in a mass ratio of 3:3:3); (2) Mix the raw material powder evenly, press it into a blank at a pressure of 400 MPa for 20 s, and heat the blank to the vacuum hot pressing sintering temperature of 750℃, 800℃, 850℃ and 900℃ respectively, and sinter it under vacuum hot pressing at a pressure of 20 MPa for 30 min. Cool it to room temperature with the furnace to obtain copper-based friction material; the copper-based friction material samples with sintering temperatures of 750℃, 800℃, 850℃ and 900℃ are recorded as samples D1, D2, D3 and D4 respectively. The average kinetic friction coefficients of the copper-based friction materials D1, D2, D3, and D4 in this comparative example are 0.33, 0.37, 0.41, and 0.35, respectively, and their wear rates are 2.33 × 10⁻⁶. -7 cm 3 / J、2.02×10 -7 cm 3 / J, 1.87×10 -7 cm 3 / J, 2.24×10 -7 cm 3 The hardness values ​​were 41HB, 48HB, 55HB, and 42HB, respectively, and the compressive strengths were 130MPa, 170MPa, 220MPa, and 150MPa, respectively.

[0034] Comparative Example 2: The copper-containing electronic waste from Example 2 was subjected to coarse crushing, fine crushing, air separation, magnetic separation, ball milling, sieving, shaking table gravity separation, ball milling for impurity removal, acid leaching for impurity removal (dilute sulfuric acid, solid-liquid ratio 1:5, temperature 60℃, leaching for 2 hours), ball milling for finer processing, and drying to obtain pure copper powder (purity 99.2%). Copper-based friction materials were prepared using traditional powder metallurgy methods, with the following specific steps: (1) Weigh the raw material powders by mass percentage: 78% pure copper powder (99.2% purity), 8% tin powder (≥99% purity), 2% iron powder (≥98% purity), 2% lead powder, 1% zinc powder, and 9% friction components (graphite, SiO2, SiC in a mass ratio of 3:3:3). (2) Mix the raw material powder evenly, press it into a blank at a pressure of 400 MPa for 20 s, and heat the blank to the vacuum hot pressing sintering temperature of 750℃, 800℃, 850℃ and 900℃ respectively, and sinter it under vacuum hot pressing at a pressure of 20 MPa for 30 min. Cool it to room temperature with the furnace to obtain copper-based friction material; the copper-based friction material samples with sintering temperatures of 750℃, 800℃, 850℃ and 900℃ are recorded as samples E1, E2, E3 and E4 respectively. The average kinetic friction coefficients of the copper-based friction materials E1, E2, E3, and E4 in this comparative example are 0.32, 0.36, 0.40, and 0.38, respectively, and their wear rates are 2.36 × 10⁻⁶. -7 cm 3 / J、2.19×10 -7 cm 3 / J, 1.96×10 -7 cm 3 / J、2.14×10 -7 cm 3 The hardness values ​​were 41HB, 50HB, 58HB, and 45HB, respectively, and the compressive strength values ​​were 140MPa, 180MPa, 200MPa, and 160MPa, respectively.

[0035] The copper-based friction materials prepared in Examples 1-3 all meet or exceed the key indicators such as hardness, compressive strength, wear rate, and coefficient of friction of materials prepared by the traditional pure metal powder method (Comparative Example 1). The embodiments of the present invention directly utilize the copper-rich alloy obtained by smelting waste circuit boards, eliminating the cost of purchasing high-cost raw materials such as electrolytic copper powder, tin powder, and iron powder, and avoiding the complex physical sorting and acid leaching impurity removal steps in the copper powder recycling process, thus reducing the overall cost by about 30-50%. Compared with Comparative Example 2, the present invention eliminates multiple crushing, sorting, ball milling, acid leaching and other processes, shortening the process by more than 50%, and there is no waste acid discharge, making it environmentally friendly. Examples 1-3 obtained copper-rich alloys (Sn 5%-10%, Fe 1%-2%) with different Sn and Fe contents by adjusting the ratio of waste circuit boards and slag-forming agents and smelting conditions. The corresponding friction material properties can cover a wide range from low to high friction coefficients and can be flexibly adjusted according to downstream needs. Therefore, the method for preparing copper-based friction materials from copper-containing electronic waste provided by this invention not only realizes the efficient resource utilization of electronic waste, but also produces products with excellent performance and low cost, and has good prospects for industrial application.

[0036] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing copper-based friction materials from copper-containing electronic waste, characterized in that, The specific steps are as follows: (1) Mix copper-containing electronic waste and copper-containing solid waste evenly to obtain a mixture, add the mixture to a smelting pool and heat to melt, and introduce oxygen-enriched gas for oxidative smelting to obtain an oxidative smelting melt; the copper-containing solid waste is one or more of copper smelting slag, copper blowing slag, and copper-containing sludge. (2) Add a reducing agent to the oxidative smelting melt, introduce a protective gas for stirring and heat preservation smelting, and separate copper-rich alloys and slag by sedimentation. (3) The copper-rich alloy is pulverized to obtain copper alloy powder, the copper alloy powder and the friction component are mixed evenly, pressed into a blank, and the blank is sintered to obtain copper-based friction material; the friction component is one or more of graphite, silicon dioxide, silicon carbide and barium sulfate.

2. The method for preparing copper-based friction materials from copper-containing electronic waste according to claim 1, characterized in that: By mass percentage, copper-containing electronic waste contains 10-30% Cu, 2-10% Sn, 1-2% Pb, 1-5% Ni, 5-12% Ca, 2-6% Al, 12-20% Si, and 1-5% Br.

3. The method for preparing copper-based friction materials from copper-containing electronic waste according to claim 1, characterized in that: Step (1) The oxygen concentration in the oxygen-enriched gas is 30~60 vol.%, and the oxygen flow rate in the oxygen-enriched gas is 0.5~2 L / min.

4. The method for preparing copper-based friction materials from copper-containing electronic waste according to claim 1, characterized in that: Step (1) The oxidation smelting temperature is 1200~1400℃ and the smelting time is 1~2h; the mass ratio of Fe to SiO2 during the oxidation smelting process is 1.0~1.4:

1.

5. The method for preparing copper-based friction materials from copper-containing electronic waste according to claim 1, characterized in that: Step (2) The reducing agent is one or more of anthracite, biochar, and biomass oil; the amount of reducing agent added is 2.5 to 10% of the mass of the copper-rich alloy.

6. The method for preparing copper-based friction materials from copper-containing electronic waste according to claim 1, characterized in that: Step (2) The temperature for heat preservation reduction smelting is 1200~1400℃, and the smelting time is 1~2h.

7. The method for preparing copper-based friction materials from copper-containing electronic waste according to claim 1, characterized in that: By mass percentage, the copper-rich alloy in step (2) contains 70-90% Cu, 5-10% Sn, 1-5% Fe, 1-3% Pb, and 0.5-2% Zn.

8. The method for preparing copper-based friction materials from copper-containing electronic waste according to claim 1, characterized in that: Step (3) The particle size of the copper alloy powder is 10~60μm, and the mass ratio of the copper alloy powder to the friction component is 6~10:

1.

9. The method for preparing copper-based friction materials from copper-containing electronic waste according to claim 1, characterized in that: Step (3) The sintering method is vacuum hot pressing sintering or discharge plasma sintering, the sintering temperature is 700~900℃, the holding time is 30~120min, and the sintering pressure is 10~50MPa.

10. The method for preparing copper-based friction materials from copper-containing electronic waste according to claim 1, characterized in that: The copper-based friction material has a coefficient of friction of 0.25~0.60 and a wear rate of ≤2.5×10⁻⁶. -7 cm 3 / J, hardness is 40~80HB.

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