Method for deep dephosphorization of copper-iron non-ferrous metal solid waste and preparation of copper-iron alloy

Abstract

The application provides a method for deep depletion of copper-iron non-ferrous metal solid waste and preparation of copper-iron alloy, relates to the technical field of comprehensive recovery and utilization of non-ferrous metal solid waste, and solves the technical problems that the existing copper slag pyrometallurgical depletion recovery technology has low recovery and utilization rate of copper and iron, and the recovered magnetic iron has low content and is not easy to utilize.The application uses carbon-containing waste as a reducing agent, uses part of components of white clay as a slagging agent, simultaneously uses trace TiO2 and Na2O in the white clay, and strengthens the copper slag smelting process.In the deep depletion process, the copper and iron recovery rates reach more than 90%, the residual amounts of copper and iron in the slag are reduced to 0.1wt% and 4.0wt% or less, respectively, in the smelting process, the paper white clay and various carbon-containing waste are used, the comprehensive utilization of solid waste is realized, and the resource utilization efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of comprehensive recycling technology for non-ferrous metal solid waste, and more specifically, to a method for deep depletion of copper and iron non-ferrous metal solid waste and preparation of copper-iron alloys. Background Technology

[0002] Copper is an important non-ferrous metal with excellent electrical and thermal conductivity and corrosion resistance, making it widely used in electronics, electrical engineering, construction, and chemical industries. However, the increasing consumption of copper has led to the generation of large quantities of copper slag, causing negative environmental impacts. Furthermore, copper slag contains considerable amounts of copper and iron resources; without effective recycling, this would result in a significant waste of these strategic metals. Statistics show that the pyrometallurgical process produces approximately 2-3 tons of copper slag for every ton of copper produced. Based on this, my country produces over ten million tons of copper slag annually. If this slag is not treated promptly, heavy metals within it will leach into the soil and rivers through prolonged exposure to rain and wind, causing secondary environmental pollution. Therefore, the depletion and utilization of copper slag is of great importance.

[0003] Currently, the main methods for treating copper slag include slow-cooling flotation and pyrometallurgical depletion. Slow-cooling flotation is characterized by low energy consumption and high recovery rate. Due to the slow cooling process, the copper mineral particles in the resulting slag are relatively coarse. Short-term grinding can liberate some of these coarse copper mineral particles, and slow-cooling flotation is used to produce these coarse copper mineral particles that have met the flotation requirements. Pyrometallurgical depletion involves adding a reducing agent to the copper slag and smelting it at high temperatures to effectively separate the slag and copper, thus obtaining copper metal.

[0004] For example, patent CN113186404A proposes a hot vortex depletion method for copper slag. This method involves loading a stirrer into the copper slag layer to create a vortex, making the temperature field inside the furnace more uniform and shortening the depletion reaction time. A depletion agent is added to carry out the vortex depletion reaction. The depleted slag contains about 0.22% Cu by mass. This patent strengthens the reduction process and improves the metal recovery rate by stirring the melt with a vortex. Patent CN108728664A proposes a method for strengthening the depletion of copper smelting slag with waste iron oxide desulfurizing agent. This method involves mixing waste iron oxide desulfurizing agent and other reagents to prepare depletion agent pellets, which are then put into a copper smelting slag depletion electric furnace for depletion, achieving the purpose of treating waste with waste. The resulting depleted slag contains less than 0.35 wt% copper and more than 15 wt% matte. While the two methods mentioned above can recover copper resources from copper slag, the copper content in the depleted slag is still above 0.2%, retaining significant recovery value. Furthermore, the iron in copper smelting slag mainly exists in the form of fir olivine and ferrosilicon, with high iron content and extremely fine particle size, making comprehensive utilization difficult. Existing technologies mostly employ processes such as magnetic roughing, regrinding, magnetic cleaning, and reverse flotation to recover iron concentrate from copper tailings from copper slag and for heavy media beneficiation experiments in coal preparation.

[0005] For example, patent CN109647616A discloses a method for comprehensively recovering magnetite and copper minerals from copper slag flotation tailings. First, magnetic roughing is performed, with the copper slag flotation tailings subjected to magnetic separation at 1800 Gs to 2200 Gs, yielding magnetic rough concentrate and magnetic tailings. Then, a shaking table gravity separation process is performed, adding 450 g / t to 550 g / t of water glass and 15 g / t to 25 g / t of Z200 to a mixing tank for 5 minutes. After further grinding and magnetic separation, the magnetic rough concentrate and the shaking table concentrate are combined and sent to a ball mill for regrinding, with lime added as a grinding aid. Finally, copper minerals are recovered by flotation. This process is relatively complex and energy-intensive, yielding only magnetite concentrate.

[0006] Existing copper slag recycling processes require the addition of strong oxidants for reduction reactions, resulting in drawbacks such as high costs, complex processes, and impure iron powder obtained after recovery and separation, making it difficult to recycle. The purpose of this invention is to address these problems, solve the issues of copper and iron resource waste and environmental pollution from copper slag, and achieve efficient recovery and high-value utilization of valuable metals from copper slag. Summary of the Invention

[0007] Producing one ton of crude pulp generates nearly 0.5 tons of white mud. my country produces approximately 10 million tons of white mud annually, but only a small portion is currently utilized; the majority is left in open-air dumps, occupying vast amounts of land and polluting the environment. The main component of white mud is calcium carbonate (approximately 90%), along with small amounts of MgO, SiO2, Al2O3, and trace amounts of TiO2 and Na2O. These oxides can be used as slag-forming agents in non-ferrous metal pyrometallurgical processes. For example, patent CN113201653A proposes an integrated method for the side-top composite blowing molten reduction of depleted copper slag. The slag-forming agent and reducing agent are limestone and coke, respectively, which are added to the depleted slag pool along with the copper slag. The final depleted slag contains 0.39-0.48% copper. However, even using a single limestone slag-forming agent to deplete copper slag still results in a significant copper loss, which has high recycling value. This invention adds papermaking sludge, whose main chemical component, calcium carbonate, regulates the melting properties (viscosity and fluidity) of copper slag. Magnesium oxide and aluminum oxide are used as fluxes. The calcium carbonate generates partial calcium oxide, which promotes the decomposition of olivine in the copper slag. This strengthens the copper slag melting and smelting process, accelerates the depletion rate, and is more conducive to the settling of valuable metals in the slag, thus deeply depleting the copper and iron valuable metals in the copper slag.

[0008] Copper-iron alloys are highly favored for their excellent electrical and thermal conductivity, high strength, and wear resistance, and have wide applications in cutting-edge fields such as communications, electromagnetic shielding, automotive manufacturing, medical devices, and high-performance electronic products. For example, copper-iron plates and strips can be used for mobile phone heat sinks, shielding covers, large-size OLED backplane materials, large-size LED display heat sinks, electrical connectors, wireless charging circuit boards, and air conditioner condenser pipes. Copper-iron alloy rods, bars, and wires can be used for electromagnetic shielding cables, high-fidelity audio cables, electromagnetic shielding wires for high-speed motors in drones, high-voltage cables, robot communication control lines, radio frequency cables, braided electromagnetic shielding mesh / belts for marine aquaculture cages, and welding wires. Copper-iron alloy powders can be used for brake pad absorbing and shielding coatings, 3D printing, and medical antibacterial applications (such as for diabetic wound healing). The impurity content in copper-iron alloys varies widely; generally, an impurity content of no more than 0.5% is ideal. These impurities mainly include zinc, lead, nickel, tin, sulfur, aluminum, and magnesium. These impurities have a significant impact on the alloy's performance, so controlling the impurity content is crucial for ensuring the quality and performance of copper-iron alloys. The molten metal after the copper and iron valuable metals in the copper slag are deeply depleted by papermaking white mud meets the impurity requirements of copper-iron alloys. A qualified copper-iron alloy can be obtained by adding a portion of pure metal.

[0009] In summary, this invention provides a method for deep depletion of copper and iron non-ferrous metal solid waste and preparation of copper-iron alloys, thereby solving the technical problems of low copper and iron recovery rates and low magnetic iron content in existing copper slag pyrometallurgical depletion and recycling technologies, which are not easy to utilize.

[0010] The embodiments of the present invention are achieved through the following technical solutions:

[0011] A method for deep depletion of copper-iron non-ferrous metal solid waste and preparation of copper-iron alloys includes the following steps:

[0012] S1: Mix copper slag, carbon-containing waste and papermaking sludge after drying, grinding and sieving;

[0013] S2: Place the mixture obtained in step S1 into a melting furnace, heat it up, introduce protective gas N2, and then keep it at that temperature for a period of time;

[0014] S3: Separate the copper-iron molten metal obtained from step S2 from the slag, and discharge the slag from the slag discharge port of the smelting furnace;

[0015] S4: The copper and iron molten metal remaining after slag removal in step S3 is further refined and impurities removed in the smelting furnace. Protective gas N2 is introduced, and desulfurizing agent is added to remove sulfur-containing impurities in the alloy, controlling the impurity content to <0.5%.

[0016] S5: Add pure copper to the refined and impurity-removed copper-iron molten metal and continue refining to obtain a copper-iron alloy product.

[0017] This technical solution uses various carbon-containing waste materials as reducing agents and heat sources. By adding papermaking sludge, the main chemical component of which, calcium carbonate, is used to regulate the melting properties (viscosity and fluidity) of copper slag. Magnesium oxide and aluminum oxide are used as fluxes. The calcium carbonate generates partial calcium oxide, which promotes the decomposition of olivine in the copper slag, thereby improving the iron recovery rate. Furthermore, the trace amounts of TiO2 and Na2O in the sludge can be utilized to enhance the copper slag melting and smelting process, accelerate the depletion rate, and reduce the impurity content of the copper-iron molten metal. By adding pure copper, a qualified copper-iron alloy is obtained, thus efficiently utilizing the copper and iron recovered from the copper slag.

[0018] Preferably, in step S1, the mass ratio of the copper slag to the carbon-containing waste and papermaking sludge is 100:8-16:10-20.

[0019] By adopting this technical solution and using the above-mentioned mass ratio of mixed materials, it is ensured that the copper slag, papermaking mud, and carbon-containing waste are fully mixed and in contact. At the same time, the amount of reducing agent and slagging agent required for subsequent processing is calculated to ensure that the content of carbon-containing waste as reducing agent and part of papermaking mud as slagging agent meets the reaction requirements of copper slag.

[0020] Preferably, in step S1, the papermaking sludge is derived from solid waste generated during the alkaline chemical pulping process in papermaking, and its main components are >90% wt% CaCO3, 1 wt% to 1.2 wt% MgO, 1.1 wt% to 1.3 wt% SiO2 and 2.4 wt% to 2.6 wt% Al2O3.

[0021] This technical solution utilizes calcium carbonate to regulate the melting properties (viscosity and fluidity) of copper slag, and uses magnesium oxide and aluminum oxide as fluxes to lower the melting temperature of copper slag and accelerate its melting. Calcium carbonate decomposes at high temperatures to generate some calcium oxide, which promotes the decomposition of olivine in copper slag, thereby improving the iron recovery rate and facilitating the settling of valuable metals in the slag, thus deeply depleting the copper and iron valuable metals in the copper slag.

[0022] Preferably, in step S1, the papermaking sludge also contains 0.15-0.25% TiO2, 0.45-0.55% Na2O, and other trace elements.

[0023] Because TiO2 is a white pigment with a high refractive index, it can be used as an opaque pigment in papermaking. Therefore, papermaking slurry also contains trace amounts of TiO2 and other trace elements such as Na2O. Na2O also acts as a flux to lower the melting temperature of the melt. The introduction of TiO2 lowers the melting temperature of the melt, and the vibrational bands of silicon-oxygen tetrahedra in the melt structure gradually become flatter, and the complex silicate network structure is depolymerized. Using this technical solution, TiO2 and Na2O are used to further enhance the copper slag melting and smelting process.

[0024] Preferably, in step S1, the proportion of the carbon-containing waste with a particle size of <0.074mm is greater than 90%.

[0025] By adopting this technical solution, the particle size requirement of carbon-containing waste can be guaranteed to ensure that the carbon-containing waste is fully mixed with other materials in the mixture, thereby achieving a full reaction.

[0026] Preferably, in step S1, the proportion of the copper slag with a particle size of <0.30mm is greater than 95%.

[0027] The purpose of adopting this technical solution is, as above, to ensure that the copper slag is fully mixed and reacted with other materials.

[0028] Preferably, in step 1, the mixture is heated to 1350°C to 1450°C in a melting furnace and held at that temperature for 60 min to 120 min.

[0029] By adopting this technical solution, the addition of white mud contains sufficient flux, which effectively reduces the melting temperature of copper slag, effectively saves energy consumption, and allows the copper slag and reducing agent to react fully during heat preservation.

[0030] Preferably, in step S3, the copper and iron content in the slag is determined.

[0031] This technical solution is used to determine the iron and copper content in the slag, and further determine the remaining iron and copper content in the copper-iron metal melt.

[0032] Preferably, based on the analysis results of the residual copper and iron content in the slag discharged in step S3, the amount of pure copper to be added in step S5 for further refining is determined so that the mass ratio of copper to iron in the copper-iron metal melt is 1:8 to 9.5.

[0033] Using this technical solution, the remaining iron and copper content in the copper-iron molten metal is determined according to step S3, so as to calculate the amount of pure copper to be added, so that the copper-iron mass ratio in the final copper-iron alloy is kept within a suitable range.

[0034] Preferably, in step S3, the residual amount of copper in the discharged slag is <0.1wt% and the residual amount of iron is <4.0wt%.

[0035] Using this technical solution, the slag is discharged for testing, which facilitates the determination of the amount of pure copper to be added and ensures that the reduction process is fully carried out. Under the action of flux and other components in the white mud, the metal content in the slag is reduced, and the metal recovery rate is improved. When the metal content of the discharged slag is high, the machine can be stopped in time for inspection and correction.

[0036] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0037] 1. After depletion, the copper residue in the copper slag is reduced to below 0.1 wt%, and the iron residue is reduced to below 4.0 wt.%, thus achieving efficient recovery of copper and iron from the copper slag.

[0038] 2. This invention utilizes papermaking sludge and various carbon-containing waste materials during the smelting process, thereby achieving comprehensive utilization of solid waste, improving resource utilization efficiency, improving the environment, and promoting green economic development.

[0039] 3. The copper-iron metal melt of this invention has a low impurity content and can be directly used to supplement pure metals to prepare copper-iron alloys, thereby achieving efficient utilization of recycled copper and iron. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the process flow for the method of deep depletion of copper and iron non-ferrous metal solid waste and preparation of copper-iron alloys provided in Embodiment 1 of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0043] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0044] The white mud used in this invention is derived from solid waste generated during the alkaline chemical pulping process in papermaking. Its trace elements are utilized to enhance the copper slag smelting process. The introduction of trace amounts of Na₂O can act as a flux to reduce the viscosity and melting temperature of the slag. The main components of the papermaking white mud are shown in Table 1.

[0045] Table 1. Main components of papermaking bleach.

[0046] Element <![CDATA[CaCO3]]> MgO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[TiO2]]> <![CDATA[Na2O]]> Content / wt% ＞90 1.1±0.1 1.2±0.1 2.5±0.1 0.2±0.05 0.5±0.05

[0047] Example 1

[0048] S1: A certain copper slag (Fe content 34.35wt%, Cu content 0.51wt%), waste cathode carbon (fixed carbon 64.3wt%), and papermaking white mud (CaCO3 90.0wt%, SiO2 1.12wt%, MgO 1.05wt%, Al2O3 2.41wt%, TiO2 0.15wt%, Na2O 0.5wt%) were ground, dried, and then sieved.

[0049] S2: Mix copper slag with waste cathode carbon powder and papermaking white mud in a certain proportion. The mass ratio of copper slag to waste cathode carbon and papermaking white mud is 100:8:10.

[0050] S3: Add the mixture obtained in step S2 into the melting furnace, heat it to the set temperature of 1425℃, introduce protective gas N2 (>99.99 vol.%), and hold it for 120 min;

[0051] S4: Separate the molten metal from the slag, and test and calculate the copper and iron content in the slag before and after reduction. The copper and iron recovery rates are 91.14% and 90.11%, respectively, and the remaining copper and iron in the slag are 0.05wt% and 3.40wt%, respectively.

[0052] S5: After adding 2.98wt% pure copper (>99.9%) to the molten metal, further refining is carried out. Protective gas N2 is introduced, and a desulfurizing agent is added to remove sulfur-containing impurities from the alloy, resulting in a copper-iron alloy product with an alloy content of 96wt%, an impurity content of 4wt%, and a copper to iron mass percentage of 1:9.

[0053] Example 2

[0054] S1: A certain copper slag (38.76wt%, Cu 0.77wt%), coking coal (fixed carbon 85.34wt.%), and papermaking mud (CaCO3 91.43wt%, SiO2 0.51wt%, MgO 1.10wt%, Al2O3 2.13wt%, TiO2 0.20wt%, Na2O 0.47wt%) were ground, dried, and then sieved.

[0055] S2: Mix copper slag with waste cathode carbon powder and papermaking white mud in a certain proportion. The mass ratio of copper slag to waste cathode carbon and papermaking white mud is 100:10:12.

[0056] S3: Add the mixture obtained in step S2 into the melting furnace, heat it to the set temperature of 1440℃, introduce protective gas N2 (>99.99 vol.%), and hold it for 100 min;

[0057] S4: The molten metal and slag are separated, and the copper and iron content in the slag before and after reduction is detected and calculated. The copper and iron recovery rates are 94.05% and 92.77%, respectively, and the residual amounts of copper and iron in the slag are 0.05wt% and 2.80wt%, respectively.

[0058] S5: After adding 3.27wt% pure copper (>99.9%) to the molten metal, further refining is carried out. Protective gas N2 is introduced, and a desulfurizing agent is added to remove sulfur-containing impurities from the alloy, resulting in a copper-iron alloy product with an alloy content of 97wt%, an impurity content of 3wt%, and a copper to iron mass percentage of 1:9.

[0059] Example 3

[0060] S1: A certain copper slag (Fe 42.02wt%, Cu 1.42wt%), waste rubber tires (fixed carbon 29.3wt%), and papermaking mud (CaCO3 91.46wt%, SiO2 1.18wt%, MgO 0.74wt%, Al2O3 2.22wt%, TiO2 0.08wt%, Na2O 0.33wt%) were ground, dried, and then sieved.

[0061] S2: Mix copper slag with waste cathode carbon powder and papermaking white mud in a certain proportion. The mass ratio of copper slag to waste cathode carbon and papermaking white mud is 100:12:10.

[0062] S3: Add the mixture obtained in step S2 into the melting furnace, heat it to the set temperature of 1450℃, introduce protective gas N2 (>99.99 vol.%), and hold it for 80 minutes;

[0063] S4: The molten metal and slag are separated, and the copper and iron content in the slag before and after reduction is detected and calculated. The copper and iron recovery rates are 92.84% and 90.88%, respectively, and the residual amounts of copper and iron in the slag are 0.10wt% and 3.83wt%, respectively.

[0064] S5: After adding 2.93wt% pure copper (>99.9%) to the molten metal, further refining is carried out. Protective gas N2 is introduced, and a desulfurizing agent is added to remove sulfur-containing impurities from the alloy, resulting in a copper-iron alloy product with an alloy content of 97wt%, an impurity content of 3wt%, and a copper to iron mass percentage of 1:9.

[0065] Comparative Example 1

[0066] Comparative Example 1 used the same batch of copper slag and coking coal as Example 2.

[0067] S1: Copper slag (38.76 wt%, Cu 0.77 wt%), coking coal (fixed carbon 85.34 wt.%), and calcium carbonate (99.97%) were ground, dried, and then screened.

[0068] S2: Mix copper slag with waste cathode carbon powder and calcium carbonate in a certain proportion. The mass ratio of copper slag to waste cathode carbon and calcium carbonate is 100:10:12.

[0069] S3: Add the mixture obtained in step S2 into the melting furnace, heat it to the set temperature of 1440℃, introduce protective gas N2 (>99.99 vol.%), and hold it for 120 min;

[0070] S4: The molten metal and slag are separated, and the copper and iron content in the slag before and after reduction is detected and calculated. The copper and iron recovery rates are 87.26% and 84.87%, respectively, and the residual copper and iron in the slag are 0.12wt% and 3.8wt%, respectively.

[0071] S5: After adding 3.27wt% pure copper (>99.9%) to the molten metal, further refining is carried out. Protective gas N2 is introduced, and a desulfurizing agent is added to remove sulfur-containing impurities from the alloy, resulting in a copper-iron alloy product with an alloy content of 97wt%, an impurity content of 3wt%, and a copper to iron mass percentage of 1:9.

[0072] The relevant data for the above embodiments and comparative examples are shown in Table 2. The copper and iron content and related calculation data for the above embodiments and comparative examples are shown in Table 3.

[0073] Table 2. Relevant data for Examples 1-3 and Comparative Examples

[0074]

[0075]

[0076] Table 3. Relevant data on copper and iron content in Examples 1-3 and comparative examples.

[0077]

[0078]

[0079] It should be noted that in Table 3, for ease of calculation and intuitive representation, the copper and iron content in the slag discharge and the amount of pure copper added are uniformly converted into the mass percentage of the copper slag in step S1. Therefore, the copper and iron content in the melt does not represent its content in the copper-iron alloy.

[0080] It can be seen that, compared with the addition of calcium carbonate alone to the mixed copper slag in Comparative Example 1, the addition of papermaking white mud to copper slag in Examples 1-3 has a better effect on strengthening the copper slag melting and smelting process and a higher copper and iron recovery rate. Specifically, in Examples 1-3, because Example 2 uses coking coal as a reducing agent, and the coking coal has a higher carbon content, under the scheme of this application, in order to ensure the requirements of mixing particle size, etc., under the same mass ratio, the coking coal provided by Example 2 has a much higher carbon content than that of Examples 1 and 3, and a higher degree of reduction. Therefore, its copper and iron recovery rate is slightly higher than that of Examples 1 and 3. The carbon content of Example 2 is about 1.66 times that of Example 1 and 2.43 times that of Example 3. However, its copper and iron recovery rate is only 1-3 percentage points higher than that of Examples 1 and 3, and the improvement is not significant. It can be seen that the technical solution of this application, by using papermaking white mud as a dopant and utilizing its flux and other components to lower the melting temperature and strengthen the copper slag melting and smelting process, improves the copper and iron recovery rate while reducing the carbon source requirements, allowing it to use carbon-containing waste to achieve a good melting and smelting effect, reducing costs and being environmentally friendly.

[0081] Furthermore, because the papermaking white mud enhances the copper slag melting and smelting process, the impurity content in the copper-iron metal melt is lower. In the subsequent preparation of the copper-iron alloy, the raw materials and addition amounts in Example 2 are the same as those in Comparative Example 1. With the use of papermaking white mud, the degree of smelting is improved, the copper-iron metal content in the slag is reduced, and the copper-iron recovery rate is improved. Therefore, the amount of pure copper that needs to be added is reduced from 3.33 to 3.27, reducing the amount of pure copper used, and the resulting copper-iron alloy has a higher alloy ratio.

[0082] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for deep depletion of copper and iron non-ferrous metal solid waste and preparation of copper-iron alloys, characterized in that: Includes the following steps: S1: Mix copper slag, carbon-containing waste and papermaking sludge after drying, grinding and sieving; S2: Place the mixture obtained in step S1 into a melting furnace, heat it up, introduce protective gas N2, and then keep it at that temperature for a period of time; S3: Separate the copper-iron molten metal obtained from step S2 from the slag, and discharge the slag from the slag discharge port of the smelting furnace; S4: The copper-iron molten metal remaining after slag removal in step S3 is further refined and impurity removed in the smelting furnace. Protective gas N2 is introduced and desulfurizing agent is added to control the sulfur content of impurities in the copper-iron molten metal to <0.5wt%. S5: Add pure copper to the refined and impurity-removed copper-iron molten metal and continue refining to obtain a copper-iron alloy product; In step S1, the mass ratio of the copper slag to the carbon-containing waste and the papermaking sludge is 100:8-16:10-20, and the mixture is heated to 1350℃-1450℃ in a smelting furnace for 60-120 minutes.

2. The method for deep depletion of copper-iron non-ferrous metal solid waste and preparation of copper-iron alloys according to claim 1, characterized in that: In step S1, the papermaking sludge is derived from solid waste generated during the alkaline chemical pulping process in papermaking. Its main components are >90 wt% CaCO3, 1 wt% to 1.2 wt% MgO, 1.1 wt% to 1.3 wt% SiO2 and 2.4 wt% to 2.6 wt% Al2O3.

3. The method for deep depletion of copper-iron non-ferrous metal solid waste and preparation of copper-iron alloys according to claim 2, characterized in that: In step S1, the papermaking sludge also contains 0.15wt% to 0.25wt% TiO2, 0.45wt% to 0.55wt% Na2O, and other trace elements.

4. The method for deep depletion of copper-iron non-ferrous metal solid waste and preparation of copper-iron alloys according to any one of claims 1-3, characterized in that: In step S1, the mass percentage of the carbon-containing waste with a particle size of <0.074mm is greater than 90%.

5. A method for deep depletion of copper-iron non-ferrous metal solid waste and preparation of copper-iron alloys according to any one of claims 1-3, characterized in that: In step S1, the mass percentage of the copper slag with a particle size of <0.30mm is greater than 95%.

6. The method for deep depletion of copper-iron non-ferrous metal solid waste and preparation of copper-iron alloys according to any one of claims 1-3, characterized in that: In step S3, the copper and iron content in the slag is determined.

7. The method for deep depletion of copper-iron non-ferrous metal solid waste and preparation of copper-iron alloys according to claim 6, characterized in that: Based on the analysis results of the residual copper and iron content in the slag discharged in step S3, the amount of pure copper to be added in step S5 for further refining is determined so that the mass ratio of copper to iron in the copper-iron metal melt is 1:8 to 9.

5.

8. The method for deep depletion of copper-iron non-ferrous metal solid waste and preparation of copper-iron alloys according to claim 7, characterized in that: In step S3, the residual amount of copper in the discharged slag is <0.1 wt%, and the residual amount of iron is <4.0 wt%.

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