Deep purification method for metal impurities in regenerated copper melt

Abstract

The invention discloses a secondary copper melt metal impurity deep purification method, which relates to the field of secondary metal treatment, and comprises the following steps: S101, shaft furnace pretreatment: preparing a secondary copper material, a shaft furnace, a first tilting refining furnace, a second tilting refining furnace, a zirconia ceramic filter, a holding furnace and a condensing device; s102, segregation type impurity removal is conducted, specifically, a first tilting refining furnace and a second tilting refining furnace are used for impurity removal, and S103, final purification is conducted through a heat preservation furnace. The method has the advantages that the impurity removal efficiency is high, the purity of the regenerated copper is improved, the process stability is high, the production cost is reduced, the environment-friendly performance is excellent, the production efficiency is improved, the adaptability is wide, and the resource utilization rate is high.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of secondary metal processing, and particularly relates to a secondary copper melt metal impurity deep purification method based on a "shaft furnace-two tilting refining furnaces-holding furnace" process system, which is particularly suitable for efficiently removing segregation type, solid solution type and volatile type metal impurities in secondary copper melt and improving the purity and performance of secondary copper. BACKGROUND

[0002] Secondary copper, as an important supplement of copper resources, is widely used in the fields of electric power, electronics, construction and the like. However, the raw materials of secondary copper are complex in origin and contain various metal impurities such as lead, bismuth, iron, nickel, zinc and cadmium. According to the characteristics, the metal impurities can be divided into three types, namely, segregation type, solid solution type and volatile type. These impurities seriously affect the electrical conductivity, mechanical properties and processing performance of secondary copper, and restrict the application of secondary copper in high-end fields.

[0003] The existing secondary copper purification process mostly adopts a "shaft furnace smelting + single refining furnace treatment" mode, which has obvious limitations. As a melting device, the shaft furnace mainly functions to melt solid raw materials into a melt, and has limited ability to remove impurities. The traditional shaft furnace has low temperature control precision (± 50℃), and cannot control the volatilization conditions of volatile impurities. Zinc and cadmium are not completely volatilized, and only 10%-20% can be removed, and the melt composition uniformity is poor.

[0004] When a single tilting refining furnace is used for treatment, it is difficult to meet the removal requirements of different types of impurities. Segregation type impurities (such as lead and bismuth) need to be separated by electromigration or gravity segregation, but the existing process lacks precise current parameter control and holding system, and the lead removal rate is only 60%-70%, and the bismuth residual amount often exceeds 0.05wt%. Solid solution type impurities (such as iron and nickel) need to be removed by chemical reaction to form compounds, but the additives in a single furnace are easy to react with other impurities, resulting in large consumption of purification agents (0.6-1.0wt%), and easy introduction of new impurities (such as sulfur and phosphorus), and the residual amount of iron and nickel is more than 0.08wt%.

[0005] The deep removal of volatile type impurities depends on a high-temperature vacuum environment, but in the existing process, the vacuum treatment is coupled with other purification steps, and the vacuum degree can only reach 50-100Pa, and the holding time is insufficient, and the residual amount of zinc often exceeds 0.05wt%, and the removal rate of cadmium is less than 70%. In addition, the existing process equipment is not well connected, and the temperature drops greatly (50-100℃) during the melt transfer process, resulting in secondary dissolution of impurities and affecting the final purification effect.

[0006] In terms of environmental protection, the volatile impurities are directly discharged in the traditional process, causing environmental pollution, and there is a lack of effective impurity recovery device, and the resource waste is serious. At the same time, improper selection of purification agents leads to an increase of 30%-50% in the amount of slag, and the subsequent treatment cost is high.

[0007] In summary, the existing "vertical furnace-single refining furnace" process cannot achieve deep and synergistic removal of the three types of impurities, making it difficult to break through 99.95% purity in recycled copper, thus failing to meet the demands of high-end applications. Therefore, developing a segmented deep purification method based on "vertical furnace-two tilting refining furnaces-holding furnace" is of great significance for promoting the upgrading of the recycled copper industry. Summary of the Invention

[0008] This invention aims to overcome the defects of existing processes and provide a method for deep purification of metallic impurities in recycled copper melt based on a "vertical furnace - two tilting refining furnaces - holding furnace". Through segmented processing, it accurately removes three types of impurities: segregation type, solid solution type, and volatile type, thereby increasing the purity of recycled copper to over 99.95%, reducing production costs, reducing environmental pollution, and meeting the demand for high-quality recycled copper in high-end fields.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a method for deep purification of metallic impurities in recycled copper melt, comprising the following steps:

[0010] S101, Vertical Furnace Pretreatment: Prepare recycled copper material, vertical furnace, first tilting refining furnace, second tilting refining furnace, zirconia ceramic filter, holding furnace and condensation device, control the feed particle size of recycled copper to 50-200mm, heat to 1100-1300℃, melting rate 1-3 tons / hour, argon protection, furnace pressure 0.1-0.3MPa, hold for 1-3 hours, use high temperature to initially volatilize 30%-40% of volatile impurities such as zinc and cadmium, and the melt is transferred to the first tilting refining furnace through the trough;

[0011] S102, Segregation type impurity removal: In the first tilting refining furnace, a pulsed current is applied to the graphite electrode for 2-5 hours to promote the electromigration and aggregation of lead and bismuth; then the temperature is raised to 1050-1200℃, a covering agent is added and the temperature is maintained for 1-3 hours for gravity segregation, and the impurity enrichment layer is removed by slag removal.

[0012] Removal of solid solution impurities: The melt is transferred to the second tilting refining furnace, and a preheated composite purifying agent is added in 3-5 batches; the mixture is stirred and reacted at 1100-1300℃ for 2-4 hours to generate insoluble compounds; the mixture is then filtered through a preheated zirconia ceramic filter to remove impurities.

[0013] S103, final purification in the holding furnace: The melt enters the holding furnace, is heated to 1200-1400℃, evacuated to 1-10Pa, and held for 1-3 hours to volatilize residual volatile impurities, which are then recovered by the condenser; subsequently, inert gas is introduced and homogenized for 0.5-1 hours to obtain high-purity recycled copper melt.

[0014] Preferably, the argon flow rate is in the range of 5-15 L / min.

[0015] Preferably, the spacing between the graphite electrodes on the first tilting furnace is 5-15 cm.

[0016] Preferably, the covering agent is charcoal powder:borax = 2:1, with a content of 0.2-0.5 wt%.

[0017] Preferably, the composite purifying agent is a boride:rare earth compound ratio of 3:2, with a content of 0.1-0.5 wt%.

[0018] Preferably, the pulse current parameter applied to the graphite electrode is 50-200 A / cm. 2 , 100-1000Hz, 10-100μs.

[0019] Preferably, when argon gas is introduced, the pressure inside the vertical furnace is maintained at 0.1-0.3 MPa through a pressure regulating valve, with a pressure fluctuation range of ≤±0.02 MPa, and the temperature gradient of the vertical furnace is controlled at 50-100℃ / m.

[0020] Preferably, the covering agent is added in two stages: the first stage adds 60%-70% of the total amount, and the remaining amount is added after 1 hour of heat preservation. The slag removal is controlled 30 minutes before the end of gravity segregation.

[0021] Preferably, the composite purifying agent is preheated in a muffle furnace at 800-1000℃ for 0.5-1 hour before use, with a preheating rate of 5-10℃ / min. After cooling to 200-300℃ in the furnace, it is added to the second tilting refining furnace in 3-5 portions, with an interval of 30-60 minutes between each addition. The addition location is in the melt vortex zone.

[0022] Preferably, the vertical shaft furnace is fed uniformly by a vibrating feeder. After crushing and screening, the particle size of the raw material is controlled at 50-200mm, the ratio of the maximum particle size to the minimum particle size is ≤4:1, the moisture content of the raw material is ≤5%, the melting rate is adjusted to 1-3 tons / hour by the feed rate, and the residence time of the melt in the vertical shaft furnace is controlled at 0.5-1.5 hours.

[0023] The technical effects and advantages of this invention are as follows:

[0024] 1. High impurity removal efficiency: Segregation impurity removal rate is 80%-95%, with lead ≤0.03wt% and bismuth ≤0.01wt%; solid solution impurities are reduced to 0.01%-0.05%, with iron ≤0.02wt% and nickel ≤0.01wt%; total removal rate of volatile impurities is 85%-98%, with zinc ≤0.02wt% and cadmium ≤0.001wt%.

[0025] 2. Improved purity of recycled copper: The final purity of recycled copper is stabilized at 99.95%-99.99%, meeting the requirements of high-end electronics, precision instruments and other fields for high-purity copper.

[0026] 3. Strong process stability: The segmented equipment has a clear division of labor, and the parameters at each stage are precise and controllable, with product quality fluctuations ≤0.02% and the pass rate increased to over 98%.

[0027] 4. Reduced production costs: The amount of composite purifying agent used is reduced by 40%-60%, energy consumption is reduced by 20%-30%, the scrap rate due to impurities is reduced to below 1%, and the overall cost is reduced by 25%-35%.

[0028] 5. Excellent environmental performance: volatile impurity recovery rate ≥90%, pollutant emissions reduced by more than 80%, slag volume reduced by 30%-50%, meeting green production standards.

[0029] 6. Improved production efficiency: Smooth equipment connection, melt transfer temperature drop ≤30℃, processing cycle shortened by 15%-20%, and single-shift capacity increased to 5-8 tons.

[0030] 7. Wide adaptability: It can process recycled copper raw materials from different sources (wires and cables, electronic waste, etc.), and can stably purify them with an initial impurity content in the range of 0.5wt%-5wt%.

[0031] 8. High resource utilization rate: It realizes the resource recovery of impurities, and lead, bismuth, zinc, cadmium and other substances can be reused as by-products, increasing the comprehensive resource utilization rate to over 95%. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the process for deep purification of metallic impurities in recycled copper melt according to the present invention. Detailed Implementation

[0033] This invention provides, for example Figure 1 The method for deep purification of metallic impurities in recycled copper melt, as shown, includes the following steps:

[0034] Vertical furnace pretreatment: Prepare recycled copper material, vertical furnace, first tilting refining furnace, second tilting refining furnace, zirconia ceramic filter, holding furnace and condensation device. Control the feed particle size of recycled copper to 50-200mm, heat to 1100-1300℃, melting rate 1-3 tons / hour, argon protection (flow rate 5-15L / min), furnace pressure 0.1-0.3MPa, hold for 1-3 hours, use high temperature to initially volatilize 30%-40% of volatile impurities such as zinc and cadmium, and transfer the melt to the first tilting refining furnace through a trough.

[0035] Segregation-type impurity removal: In the first tilting refining furnace, a pulsed current (50-200 A / cm) is applied to graphite electrodes (5-15 cm apart). 2The sample was treated at 100-1000 Hz (10-100 μs) for 2-5 hours to promote the electromigration and aggregation of lead and bismuth. Then, the temperature was raised to 1050-1200℃, and a covering agent (charcoal powder: borax = 2:1, 0.2-0.5 wt%) was added and kept at this temperature for 1-3 hours for gravity segregation. The impurity-rich layer was removed by skimming.

[0036] Removal of solid solution impurities: The melt is transferred to the second tilting refining furnace, and a preheated (800-1000℃, 0.5-1 hour) composite purifying agent (boride: rare earth compound = 3:2, 0.1-0.5wt%) is added in 3-5 portions; the mixture is stirred at 1100-1300℃ (100-300 r / min) for 2-4 hours to generate insoluble compounds; impurities are removed by filtration through a preheated (1000-1200℃, 0.5 hours) zirconia ceramic filter (5-15μm).

[0037] Final purification in the holding furnace: The melt enters the holding furnace, is heated to 1200-1400℃, evacuated to 1-10Pa, and held for 1-3 hours to volatilize residual volatile impurities. The impurities are then recovered by a condenser (100-300℃). Subsequently, inert gas (8-20L / min) is introduced and homogenized for 0.5-1 hours to obtain high-purity recycled copper melt.

[0038] It should be noted that vertical shaft furnaces are commonly used equipment in non-ferrous metal smelting, and are particularly suitable for processing recycled copper materials. Vertical shaft furnaces are used for the initial melting of recycled copper materials, and volatile impurities such as zinc and cadmium are removed through high-temperature volatilization. Vertical shaft furnaces are usually equipped with heating elements and stirring devices to ensure uniform melting of materials and effective separation of impurities. When operating a vertical shaft furnace, the feed particle size, heating rate, melting rate, protective gas flow rate and furnace pressure can be controlled to optimize melting and impurity removal efficiency.

[0039] The first and second tilting refining furnaces are key equipment in the copper melt refining process, used to remove segregated impurities such as lead and bismuth. By applying pulsed current and adding a covering agent, impurities are encouraged to migrate and aggregate, facilitating subsequent slag removal. The tilting refining furnace design allows the furnace body to tilt during the refining process to facilitate the separation and removal of impurities. During operation, pulsed current parameters (such as current density, frequency, and time), covering agent ratio and addition amount, as well as refining temperature and time can be controlled.

[0040] Zirconia ceramic filters are commonly used filtration equipment in copper melt refining to remove fine non-metallic inclusions. Through the microporous structure of the ceramic filter, fine non-metallic inclusions are physically blocked, thereby purifying the copper melt.

[0041] The holding furnace is used to maintain the temperature of the copper melt during the refining process, ensuring the refining effect, providing a stable temperature environment, and keeping the copper melt within a suitable temperature range after refining, which facilitates subsequent processing, controls the holding temperature and time, as well as the vacuum degree, to optimize the purity and quality of the melt.

[0042] The condensation unit is used to recover impurities and valuable metals that volatilize during the refining process. It recovers valuable metal vapors, such as zinc vapors, through condensation, and removes residual volatile impurities. During operation, the condensation temperature and inert gas flow rate can be controlled to optimize recovery efficiency and purity. These are all existing technologies and will not be described in detail here.

[0043] Example 1

[0044] The initial impurities in the recycled copper raw materials from wires and cables are: lead 0.5wt%, bismuth 0.3wt%, iron 0.4wt%, nickel 0.2wt%, zinc 1.2wt%, and cadmium 0.1wt%.

[0045] The recycled copper raw material from the wire and cable process is fed into a vertical furnace. The furnace is smelted at 1100℃, protected with argon gas at 5L / min, and held at that temperature for 1 hour. The melting rate is 1 ton / hour.

[0046] Then, the first tilting refining furnace is used for impurity removal, with the following parameters set: pulse current 50A / cm. 2 100Hz, 10μs, treatment for 2 hours; heat treatment at 1050℃ for 1 hour, with 0.2wt% covering agent.

[0047] Then, a second tilting refining furnace was used to remove impurities. The parameters were set as follows: 0.1 wt% composite purifying agent (preheated at 800℃ for 0.5 hours), stirred at 100 r / min at 1100℃ for 2 hours, and filtered using a ceramic filter with a 5 μm pore size.

[0048] Heating to 1200℃ and 10Pa pressure in a heat-preserving furnace, vacuuming for 1 hour, condensing to 100℃, and homogenizing for 0.5 hours by introducing argon gas at 8L / min.

[0049] Final impurity content: lead 0.05 wt%, bismuth 0.03 wt%, iron 0.04 wt%, nickel 0.03 wt%, zinc 0.15 wt%, cadmium 0.02 wt%.

[0050] It should be noted that a covering agent of 0.2-0.5 wt% of the melt mass is added. The covering agent is made by mixing charcoal powder with a particle size ≤0.15mm and industrial grade borax (purity ≥95%) at a mass ratio of 2:1, with a mixing uniformity ≥95%. The covering agent is added in two parts. The first part is 60%-70% of the total amount, and the remaining amount is added after 1 hour of heat preservation. The slag removal time is controlled at 30 minutes before the end of gravity segregation.

[0051] When argon gas is introduced, the pressure inside the vertical furnace is maintained at 0.1-0.3MPa through the pressure regulating valve, with a pressure fluctuation range of ≤±0.02MPa, and the temperature gradient of the vertical furnace is controlled at 50-100℃ / m.

[0052] The composite purifying agent is composed of boride (calcium boride CaB6 purity ≥90% or magnesium boride MgB2 purity ≥90%) and rare earth compound (cerium oxide CeO2 purity ≥99% or lanthanum oxide La2O3 purity ≥99%) in a mass ratio of 3:2. Before use, it is preheated in a muffle furnace at 800-1000℃ for 0.5-1 hours with a preheating rate of 5-10℃ / min. After cooling to 200-300℃ in the furnace, it is added to the second tilting refining furnace in 3-5 portions, with an interval of 30-60 minutes between each addition. The addition location is in the melt vortex zone.

[0053] The vacuum system of the insulation furnace adopts a three-stage vacuum pump group (mechanical pump + Roots pump + diffusion pump), with an ultimate vacuum level of ≤0.1Pa. The actual working vacuum level is controlled between 1-10Pa. Vacuum level measurement is performed using a capacitive thin-film vacuum gauge (measurement accuracy ±5%). The condensation device is a shell-and-tube condenser, with a condensation area calculated based on the evaporation rate of 0.5-2m². 2 The condensation temperature is precisely controlled between 100-300℃ by the temperature control system, with a temperature difference fluctuation of ≤±5℃, and the recovery rate of volatile impurities is ≥90% as determined by the weighing method.

[0054] Example 2

[0055] The initial impurities in the recycled copper from electronic waste are: lead 0.8wt%, bismuth 0.4wt%, iron 0.5wt%, nickel 0.3wt%, zinc 1.5wt%, and cadmium 0.15wt%.

[0056] The recycled copper from electronic waste is fed into a vertical shaft furnace. The furnace is smelted at 1150℃, protected by 99.99% pure argon gas at a flow rate of 8L / min (dew point -42℃). The pressure inside the furnace is stabilized at 0.15MPa through a regulating valve. The furnace is held at this temperature for 1.5 hours, and the melting rate is controlled at 1.5 tons / hour.

[0057] Then, the first tilting refining furnace is used for impurity removal. In the first tilting refining furnace, the graphite electrode spacing is 8 cm, and the applied pulse current parameter is 80 A / cm. 2 The temperature was 300 Hz and 30 μs for 3 hours; then the temperature was raised to 1100 ℃ for gravity segregation and held for 1.5 hours, during which 0.3 wt% covering agent (a mixture of charcoal powder and borax in a 2:1 ratio) was added.

[0058] The second tilting refining furnace was then used to remove impurities. 0.2 wt% of a composite purifying agent (MgB2:La2O3 = 3:2) was added to the second tilting refining furnace. The purifying agent was preheated at 850℃ for 0.6 hours and added to the melt vortex zone in 4 portions. The mixture was stirred at 200 r / min at 1150℃ for 2.5 hours. After the reaction, the mixture was filtered through an 8 μm zirconia filter.

[0059] The temperature was raised to 1250℃ using a heat-preserving furnace, and the vacuum was evacuated to 8Pa and maintained for 1.5 hours. The volatile impurities were recovered using a 150℃ condenser. Finally, 10L / min of argon gas was introduced for homogenization for 0.6 hours.

[0060] Final impurity test results: Lead 0.025 wt%, Bismuth 0.008 wt%, Iron 0.018 wt%, Nickel 0.009 wt%, Zinc 0.018 wt%, Cadmium 0.0008 wt%.

[0061] Example 3

[0062] Recycled copper from construction waste contains the following initial impurities: lead 1.0 wt%, bismuth 0.5 wt%, iron 0.6 wt%, nickel 0.4 wt%, zinc 1.8 wt%, and cadmium 0.2 wt%.

[0063] The recycled copper from construction waste is fed into a vertical shaft furnace. The furnace is set to a melting temperature of 1200℃, an argon flow rate of 10L / min (dew point -45℃), a furnace pressure of 0.2MPa, and is held at that temperature for 2 hours. The melting rate is 2 tons / hour.

[0064] The first tilting refining furnace is used for impurity removal. In the first tilting refining furnace, the graphite electrode spacing is 10 cm, and an A / cm pressure is applied. 2 The sample was treated with a pulsed current of 500 Hz and 50 μs for 4 hours; then it was kept at 1150 ℃ for 2 hours for gravity segregation, and 0.4 wt% covering agent (charcoal powder: borax = 2:1) was added.

[0065] Then, a second tilting refining furnace was used to remove impurities. 0.3wt% of composite purifying agent (CaB6:CeO2=3:2) was added to the second tilting refining furnace. After preheating at 900℃ for 0.7 hours, it was added in 5 portions. The mixture was stirred at 250r / min at 1200℃ for 3 hours and then filtered through a 10μm ceramic filter.

[0066] The temperature was raised to 1300℃ using a heat-preserving furnace, and the vacuum was evacuated to 5Pa and maintained for 2 hours. The volatile impurities were recovered by condensation at 200℃. Argon gas was introduced at a rate of 12L / min for homogenization for 0.7 hours.

[0067] Final impurity content: lead 0.02 wt%, bismuth 0.007 wt%, iron 0.015 wt%, nickel 0.008 wt%, zinc 0.015 wt%, cadmium 0.0007 wt%.

[0068] Example 4

[0069] Recycled copper from industrial waste contains the following initial impurities: lead 0.6 wt%, bismuth 0.35 wt%, iron 0.45 wt%, nickel 0.25 wt%, zinc 1.3 wt%, and cadmium 0.12 wt%.

[0070] Construction waste copper is recycled and fed into a vertical furnace, which is heated to 1180℃ for smelting. Argon gas is introduced for protection, with an argon flow rate of 9L / min (dew point -43℃) and a pressure of 0.18MPa. The furnace is held at this temperature for 1.8 hours, and the melting rate is 1.8 tons / hour.

[0071] The first tilting refining furnace is used for impurity removal. The electrode spacing of the first tilting refining furnace is 9 cm, and 90 A / cm is applied. 2 The sample was treated with a 400Hz, 40μs pulsed current for 3.5 hours; then held at 1120℃ for 1.8 hours for gravity segregation, and 0.35wt% covering agent was added.

[0072] The second tilting refining furnace was then used to remove impurities. 0.25wt% of composite purifying agent (MgB2:CeO2=3:2) was added to the second tilting refining furnace. After preheating at 880℃ for 0.65 hours, the agent was added in 4 batches. The mixture was stirred at 220r / min at 1180℃ for 2.8 hours and then filtered using a filter with a pore size of 9μm.

[0073] The sample was heated to 1280℃ in a heat-insulating furnace and treated under a vacuum pressure of 6Pa for 1.8 hours, with the condensation temperature reduced to 180℃; then homogenized by introducing argon gas at a rate of 11L / min for 0.65 hours.

[0074] Final impurity content: lead 0.028 wt%, bismuth 0.009 wt%, iron 0.019 wt%, nickel 0.009 wt%, zinc 0.017 wt%, cadmium 0.0009 wt%.

[0075] Example 5

[0076] Recycled copper from scrap automobiles contains the following initial impurities: lead 0.9wt%, bismuth 0.45wt%, iron 0.55wt%, nickel 0.35wt%, zinc 1.6wt%, and cadmium 0.18wt%.

[0077] The recycled copper from scrap automotive copper is fed into a vertical shaft furnace, which is heated to 1220℃ for smelting. Argon gas is introduced at a flow rate of 11L / min (dew point -44℃) and a pressure of 0.22MPa. The furnace is held at this temperature for 2.2 hours at a rate of 2.2 tons / hour.

[0078] The first tilting refining furnace is used for impurity removal. The electrode spacing of the first tilting refining furnace is 11cm, and the current is 110A / cm. 2Treatment with a 600Hz, 60μs pulsed current for 4.5 hours; heating to 1180℃ and holding for 2.2 hours; gravity segregation; 0.45wt% covering agent.

[0079] The second tilting refining furnace was used for impurity removal. 0.35wt% of composite purifying agent (CaB6:La2O3 = 3:2) was added to the second tilting refining furnace and preheated to 920℃ for 0.75 hours, then added in 5 portions. The furnace was then heated to 1220℃ and stirred at 280r / min for 3.2 hours. The mixture was then filtered using a filter with a pore size of 12μm.

[0080] Heating to 1320℃ in a heat-insulating furnace, vacuuming at 4Pa for 2.2 hours, and condensing to 220℃; then purging with argon gas at 13L / min for 0.75 hours for homogenization.

[0081] Final impurity content: lead 0.022 wt%, bismuth 0.006 wt%, iron 0.014 wt%, nickel 0.007 wt%, zinc 0.014 wt%, cadmium 0.0006 wt%.

[0082] Example 6

[0083] Recycled copper from scrap copper, with initial impurities including: lead 1.2wt%, bismuth 0.6wt%, iron 0.7wt%, nickel 0.5wt%, zinc 2.0wt%, and cadmium 0.25wt%.

[0084] The recycled copper from scrap copper is fed into a vertical furnace and heated to 1250℃ for smelting. Argon gas is introduced at a flow rate of 12L / min (dew point -45℃) and a pressure of 0.25MPa. The furnace is held at this temperature for 2.5 hours at a rate of 2.5 tons / hour.

[0085] The first tilting refining furnace is used for impurity removal. The electrode spacing of the first tilting refining furnace is 12cm, and the current is 120A / cm. 2 Treatment with a 700Hz, 70μs pulsed current for 5 hours; heating to 1200℃ and holding for 2.5 hours; gravity segregation; 0.5wt% covering agent.

[0086] Then, a second tilting refining furnace is used to remove impurities. 0.4 wt% of composite purifying agent (MgB2:La2O3 = 3:2) is added to the second tilting refining furnace, and the mixture is heated to 950℃ for 0.8 hours and added in 5 portions. The mixture is then heated to 1250℃ and stirred at 300 r / min for 3.5 hours. The mixture is then filtered using a filter with a pore size of 15 μm.

[0087] Heating to 1350℃ in a heat-insulating furnace, vacuum treatment at 3Pa for 2.5 hours, condensing to 250℃; then purging with argon gas at 15L / min for 0.8 hours for homogenization.

[0088] Final impurity content: lead 0.018 wt%, bismuth 0.005 wt%, iron 0.012 wt%, nickel 0.006 wt%, zinc 0.012 wt%, cadmium 0.0005 wt%.

[0089] Example 7

[0090] The recycled copper from scrap transformers contains the following initial impurities: lead 0.7wt%, bismuth 0.32wt%, iron 0.42wt%, nickel 0.22wt%, zinc 1.4wt%, and cadmium 0.11wt%.

[0091] The recycled copper from waste transformers is fed into a vertical furnace, which is heated to 1120℃ for smelting. The argon flow rate is 6L / min (dew point -42℃), the pressure is 0.12MPa, the holding time is 1.2 hours, and the smelting rate is 1.2 tons / hour.

[0092] The first tilting refining furnace is used for impurity removal. The electrode spacing of the first tilting refining furnace is 6cm, and the current is 60A / cm. 2 Treatment with a 200Hz, 20μs pulsed current for 2.5 hours; holding at 1080℃ for 1.2 hours for gravity segregation; 0.25wt% covering agent.

[0093] Then, a second tilting refining furnace was used to remove impurities. 0.15wt% of composite purifying agent (CaB6:CeO2=3:2) was added to the second tilting refining furnace, and the mixture was preheated to 820℃ for 0.55 hours and added in 3 batches. The mixture was then heated to 1120℃ and stirred at 150r / min for 2.2 hours. The mixture was then filtered using a filter with a pore size of 6μm.

[0094] Heated to 1220℃ in a heat-insulating furnace, vacuumed at 9Pa for 1.2 hours, and condensed to 120℃; homogenized with argon gas at 9L / min for 0.55 hours.

[0095] Final impurity content: lead 0.032 wt%, bismuth 0.01 wt%, iron 0.021 wt%, nickel 0.01 wt%, zinc 0.019 wt%, cadmium 0.001 wt%.

[0096] Example 8

[0097] The cable sheath contains recycled copper with initial impurities of: lead 0.85wt%, bismuth 0.42wt%, iron 0.52wt%, nickel 0.32wt%, zinc 1.7wt%, and cadmium 0.17wt%.

[0098] The scrap copper from the cable sheath is fed into a vertical furnace, which is heated to 1170°C for smelting. Argon gas is introduced at a flow rate of 10 L / min (dew point -43°C) and a pressure of 0.19 MPa. The furnace is held at this temperature for 1.9 hours at a rate of 1.9 tons / hour.

[0099] The first tilting refining furnace is used for impurity removal. The electrode spacing of the first tilting refining furnace is 10cm, and the current is 100A / cm. 2 Treatment with a 500Hz, 50μs pulsed current for 4 hours; heating to 1160℃ and holding for 1.9 hours; gravity segregation; 0.4wt% covering agent.

[0100] Then, a second tilting refining furnace is used to remove impurities. 0.3wt% of composite purifying agent (MgB2:CeO2=3:2) is added to the second tilting refining furnace, and the furnace is heated to 900℃ for 0.7 hours and added in 5 batches. The furnace is then heated to 1200℃ and stirred at 250r / min for 3 hours. The mixture is then filtered using a filter with a pore size of 11μm.

[0101] Heating to 1300℃ in a heat-insulating furnace, vacuuming at 5Pa for 2 hours, and condensing to 200℃; then purging with argon gas at 12L / min for 0.7 hours for homogenization.

[0102] Final impurity content: lead 0.023 wt%, bismuth 0.007 wt%, iron 0.016 wt%, nickel 0.008 wt%, zinc 0.014 wt%, cadmium 0.0006 wt%.

[0103] Example 9

[0104] Low-grade recycled copper, with initial impurities including: lead 0.55wt%, bismuth 0.25wt%, iron 0.35wt%, nickel 0.15wt%, zinc 1.1wt%, and cadmium 0.08wt%.

[0105] Low-grade recycled copper is fed into a vertical furnace, heated to 1100℃ for smelting, and argon gas is introduced at a flow rate of 5L / min (dew point -41℃) and a pressure of 0.1MPa. The furnace is held at this temperature for 1 hour at a rate of 1 ton / hour.

[0106] The first tilting refining furnace is used for impurity removal. The electrode spacing of the first tilting refining furnace is 5.5 cm, and the current is 55 A / cm. 2 Treatment with a 150Hz, 15μs pulsed current for 2 hours; heating to 1060℃ and holding for 1 hour; gravity segregation; 0.2wt% covering agent.

[0107] Then, a second tilting refining furnace was used to remove impurities. 0.12wt% of composite purifying agent (CaB6:La2O3=3:2) was added to the second tilting refining furnace and heated to 810℃ for 0.5 hours. The mixture was added in 3 batches. The furnace was then heated to 1110℃ and stirred at 120r / min for 2 hours. The mixture was then filtered using a filter with a pore size of 5μm.

[0108] Heating to 1210℃ in a heat-insulating furnace, vacuuming at 10Pa for 1 hour, and condensing to 110℃; then purging with argon gas at 8L / min for 0.5 hours for homogenization.

[0109] Final impurity content: lead 0.035 wt%, bismuth 0.012 wt%, iron 0.023 wt%, nickel 0.012 wt%, zinc 0.02 wt%, cadmium 0.0012 wt%.

[0110] Example 10

[0111] High-zinc recycled copper, with initial impurities including: lead 0.65wt%, bismuth 0.3wt%, iron 0.4wt%, nickel 0.2wt%, zinc 2.5wt%, and cadmium 0.2wt%.

[0112] High-zinc recycled copper is fed into a vertical furnace, heated to 1300℃ for smelting, and argon gas is introduced at a flow rate of 15L / min (dew point -45℃) and a pressure of 0.3MPa. The furnace is held at this temperature for 3 hours at a rate of 3 tons / hour.

[0113] The first tilting refining furnace is used for impurity removal. The electrode spacing of the first tilting refining furnace is 15cm, and the current is 150A / cm. 2 Treatment with 800Hz, 80μs pulsed current for 6 hours; heating to 1200℃ and holding for 3 hours; gravity segregation; 0.5wt% covering agent.

[0114] Then, a second tilting refining furnace is used to remove impurities. 0.5wt% of composite purifying agent (CaB6:CeO2=3:2) is added to the second tilting refining furnace, heated to 1000℃ for 1 hour and added in 5 portions; then heated to 1300℃ and stirred at 300r / min for 4 hours, and filtered using a filter with a pore size of 15μm.

[0115] Heat to 1400℃ in a heat-insulating furnace, vacuum for 3 hours at 1Pa, then condense to 300℃; introduce argon gas and homogenize at 20L / min for 1 hour.

[0116] Final impurity content: lead 0.015 wt%, bismuth 0.004 wt%, iron 0.01 wt%, nickel 0.005 wt%, zinc 0.01 wt%, cadmium 0.0003 wt%.

[0117] Example 11

[0118] Bismuth-containing recycled copper, with initial impurities including: lead 0.4wt%, bismuth 0.8wt%, iron 0.3wt%, nickel 0.1wt%, zinc 1.0wt%, and cadmium 0.05wt%.

[0119] Bismuth-containing recycled copper is fed into a vertical furnace, heated to 1150°C for smelting, and argon gas is introduced at a flow rate of 7L / min (dew point -42°C) and a pressure of 0.15MPa. The furnace is held at this temperature for 1.5 hours at a rate of 1.5 tons / hour.

[0120] The first tilting refining furnace is used for impurity removal. The electrode spacing of the first tilting refining furnace is 8cm, and the current is 80A / cm.2 Treatment with a 300Hz, 30μs pulsed current for 3 hours; heating to 1100℃ and holding for 1.5 hours; gravity segregation; 0.3wt% covering agent.

[0121] Then, a second tilting refining furnace is used to remove impurities. 0.2wt% of composite purifying agent (MgB2:La2O3=3:2) is added to the second tilting refining furnace, and the mixture is heated to 850℃ for 0.6 hours and added in 4 batches. The mixture is then heated to 1150℃ and stirred at 200r / min for 2.5 hours. The mixture is then filtered using a filter with a pore size of 8μm.

[0122] Heating to 1250℃ in a heat-insulating furnace, vacuum treatment at 8Pa for 1.5 hours, condensing to 150℃, and homogenizing with 10L / min argon gas for 0.6 hours.

[0123] Final impurity content: lead 0.03 wt%, bismuth 0.04 wt%, iron 0.018 wt%, nickel 0.009 wt%, zinc 0.018 wt%, cadmium 0.0008 wt%.

[0124] Example 12

[0125] Iron-containing recycled copper, with initial impurities including: lead 0.7wt%, bismuth 0.35wt%, iron 1.0wt%, nickel 0.6wt%, zinc 1.6wt%, and cadmium 0.15wt%.

[0126] Iron-containing recycled copper is fed into a vertical furnace, heated to 1200℃ for smelting, and argon gas is introduced at a flow rate of 12L / min (dew point -44℃) and a pressure of 0.2MPa. The furnace is held at this temperature for 2 hours at a rate of 2 tons / hour.

[0127] The first tilting refining furnace is used for impurity removal. The electrode spacing of the first tilting refining furnace is 12cm, and the current is 120A / cm. 2 Treatment with a 600Hz, 60μs pulsed current for 5 hours; heating to 1150℃ and holding for 2 hours; gravity segregation; 0.4wt% covering agent.

[0128] Then, a second tilting refining furnace is used to remove impurities. 0.4wt% of composite purifying agent (CaB6:CeO2=3:2) is added to the second tilting refining furnace, and the mixture is heated to 950℃ for 0.8 hours and added in 5 portions. The mixture is then heated to 1200℃ and stirred at 280r / min for 3.5 hours. The mixture is then filtered using a filter with a pore size of 12μm.

[0129] Heating to 1300℃ in a heat-insulating furnace, vacuuming at 5Pa for 2 hours, and condensing to 200℃; then purging with argon gas at 14L / min for 0.8 hours for homogenization.

[0130] Final impurity content: lead 0.022 wt%, bismuth 0.007 wt%, iron 0.015 wt%, nickel 0.01 wt%, zinc 0.015 wt%, cadmium 0.0006 wt%.

[0131] Example 13

[0132] Nickel-containing recycled copper, with initial impurities including: lead 0.5wt%, bismuth 0.25wt%, iron 0.4wt%, nickel 0.8wt%, zinc 1.2wt%, and cadmium 0.1wt%.

[0133] Nickel-containing recycled copper is fed into a vertical furnace, which is heated to 1180°C. Argon gas is introduced at a rate of 9 L / min (dew point -43°C) and a pressure of 0.18 MPa. The furnace is held at this temperature for 1.8 hours at a rate of 1.8 tons / hour.

[0134] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had the following parameters: electrode spacing 9cm, current 90A / cm². 2 400 Hz, 40 μs, treatment for 3.5 hours; heated to 1120℃ and held for 1.8 hours, with 0.35 wt% covering agent.

[0135] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.3wt% purifying agent (MgB2:CeO2=3:2), which is preheated to 900℃ for 0.7 hours and added in 4 portions. The mixture is then heated to 1180℃ and stirred at 250r / min for 3 hours. Finally, it is filtered using a filter with a pore size of 10μm.

[0136] Heating to 1280℃ and 6Pa vacuum in a heat-insulating furnace for 1.8 hours, condensing to 180℃, and then purging with argon gas at 12L / min for 0.7 hours for homogenization.

[0137] Final impurity content: lead 0.028 wt%, bismuth 0.009 wt%, iron 0.018 wt%, nickel 0.012 wt%, zinc 0.017 wt%, cadmium 0.0009 wt%.

[0138] Example 14

[0139] The cadmium-containing recycled copper has the following initial impurities: lead 0.6 wt%, bismuth 0.3 wt%, iron 0.35 wt%, nickel 0.2 wt%, zinc 1.4 wt%, and cadmium 0.3 wt%.

[0140] Cadmium-containing recycled copper is fed into a vertical shaft furnace, which is heated to 1220°C. Argon gas is introduced at a rate of 13 L / min (dew point -45°C) and a pressure of 0.22 MPa. The furnace is held at this temperature for 2.2 hours at a rate of 2.2 tons / hour.

[0141] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had an electrode spacing of 11 cm and a current of 110 A / cm.2 700 Hz, 70 μs, treatment for 4.5 hours; heated to 1180℃ and held for 2.2 hours, with 0.45 wt% covering agent.

[0142] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.35 wt% purifying agent (CaB6:La2O3=3:2), which is preheated to 930℃ for 0.75 hours and added in 5 portions. The mixture is then heated to 1220℃ and stirred at 280 r / min for 3.2 hours. Finally, it is filtered using a filter with a pore size of 12 μm.

[0143] Heating to 1320℃ and 3Pa vacuum in a heat-insulating furnace for 2.2 hours, condensing to 250℃, and then purging with argon gas at 15L / min for 0.75 hours for homogenization.

[0144] Final impurity content: lead 0.022 wt%, bismuth 0.006 wt%, iron 0.014 wt%, nickel 0.007 wt%, zinc 0.014 wt%, cadmium 0.0004 wt%.

[0145] Example 15

[0146] The mixed waste recycled copper has the following initial impurities: lead 1.0 wt%, bismuth 0.5 wt%, iron 0.6 wt%, nickel 0.4 wt%, zinc 1.9 wt%, and cadmium 0.22 wt%.

[0147] Mixed waste recycled copper is fed into a vertical shaft furnace, which is heated to 1250°C. Argon gas is introduced at a rate of 14 L / min (dew point -44°C) and a pressure of 0.25 MPa. The furnace is held at this temperature for 2.5 hours at a rate of 2.5 tons / hour.

[0148] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had an electrode spacing of 13cm and a current of 130A / cm. 2 700 Hz, 70 μs, treatment for 5 hours; heat to 1200℃ and hold for 2.5 hours, with 0.5 wt% covering agent.

[0149] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.4 wt% purifying agent (MgB2:CeO2=3:2), which is preheated to 960℃ for 0.8 hours. The agent is added in 5 portions and heated to 1250℃. The mixture is stirred at 300 r / min and reacted for 3.8 hours. The mixture is then filtered using a filter with a pore size of 15 μm.

[0150] Heating to 1350℃ and 2Pa vacuum in a heat-insulating furnace for 2.5 hours, condensing to 250℃, and then purging with argon gas at 17L / min for 0.85 hours for homogenization.

[0151] Final impurity content: lead 0.018 wt%, bismuth 0.005 wt%, iron 0.012 wt%, nickel 0.006 wt%, zinc 0.012 wt%, cadmium 0.0003 wt%.

[0152] Example 16

[0153] The initial impurities in the crude copper recycled material are: lead 0.8wt%, bismuth 0.4wt%, iron 0.5wt%, nickel 0.3wt%, zinc 1.5wt%, and cadmium 0.15wt%.

[0154] The crude copper recycled material is fed into a vertical furnace, which is heated to 1150°C. Argon gas is introduced at a rate of 8L / min (dew point -42°C) and a pressure of 0.15MPa. The furnace is held at this temperature for 1.5 hours at a rate of 1.5 tons / hour.

[0155] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had the following parameters: electrode spacing 9cm, current 90A / cm². 2 400 Hz, 40 μs, treatment for 3 hours; heat to 1100℃ and hold for 1.5 hours, with 0.3 wt% covering agent.

[0156] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.25 wt% purifying agent (CaB6:La2O3=3:2), which is preheated to 880℃ for 0.65 hours and added in 4 portions. The mixture is then heated to 1180℃ and stirred at 250 r / min for 2.8 hours. Finally, it is filtered using a filter with a pore size of 10 μm.

[0157] Heating to 1280℃ and 6Pa vacuum in a heat-insulating furnace for 1.8 hours, condensing to 180℃, and then purging with argon gas at 11L / min for 0.65 hours for homogenization.

[0158] Final impurity content: lead 0.025 wt%, bismuth 0.008 wt%, iron 0.017 wt%, nickel 0.009 wt%, zinc 0.016 wt%, cadmium 0.0008 wt%.

[0159] Example 17

[0160] The recycled copper from scrap brass contains the following initial impurities: lead 1.5wt%, bismuth 0.7wt%, iron 0.8wt%, nickel 0.6wt%, zinc 3.0wt%, and cadmium 0.3wt%.

[0161] Waste brass recycled copper is fed into a vertical shaft furnace, which is heated to 1300℃. Argon gas is introduced at a rate of 15L / min (dew point -45℃) and a pressure of 0.3MPa. The furnace is held at this temperature for 3 hours at a rate of 3 tons / hour.

[0162] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had the following parameters: electrode spacing 15cm, current 160A / cm.2 900 Hz, 90 μs, treatment for 6 hours; heat to 1200℃ and hold for 3 hours, with 0.5 wt% covering agent.

[0163] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.5 wt% purifying agent (MgB2:La2O3=3:2), which is heated to 1000℃ for 1 hour and added in 5 portions. The mixture is then heated to 1300℃ and stirred at 300 r / min for 4 hours. Finally, it is filtered using a filter with a pore size of 15 μm.

[0164] Heat to 1400℃ and 1Pa vacuum in a heat-insulating furnace for 3 hours, condense to 300℃, introduce argon gas, and homogenize for 1 hour at 20L / min.

[0165] Final impurity content: lead 0.015 wt%, bismuth 0.005 wt%, iron 0.01 wt%, nickel 0.005 wt%, zinc 0.01 wt%, cadmium 0.0002 wt%.

[0166] Example 18

[0167] The recycled copper from scrap bronze contains the following initial impurities: lead 0.9 wt%, bismuth 0.45 wt%, iron 0.55 wt%, nickel 0.7 wt%, zinc 1.7 wt%, and cadmium 0.18 wt%.

[0168] Waste bronze recycled copper is fed into a vertical shaft furnace, which is heated to 1220℃. Argon gas is introduced at a rate of 12L / min (dew point -44℃) and a pressure of 0.22MPa. The furnace is held at this temperature for 2.2 hours at a rate of 2.2 tons / hour.

[0169] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had an electrode spacing of 12 cm and a current of 130 A / cm. 2 600 Hz, 60 μs, treatment for 4.5 hours; heated to 1180℃ and held for 2.2 hours, with 0.45 wt% covering agent.

[0170] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.4 wt% purifying agent (CaB6:CeO2=3:2), which is preheated to 940℃ for 0.8 hours and added in 5 portions. The mixture is then heated to 1220℃ and stirred at 290 r / min for 3.2 hours. Finally, it is filtered using a filter with a pore size of 13 μm.

[0171] Heating to 1320℃ and 3Pa vacuum in a heat-insulating furnace for 2.2 hours, condensing to 230℃, and then purging with argon gas at 14L / min for 0.8 hours for homogenization.

[0172] Final impurity content: lead 0.02 wt%, bismuth 0.006 wt%, iron 0.013 wt%, nickel 0.008 wt%, zinc 0.013 wt%, cadmium 0.0006 wt%.

[0173] Example 19

[0174] The recycled copper from scrap white copper contains the following initial impurities: lead 0.6 wt%, bismuth 0.3 wt%, iron 0.4 wt%, nickel 1.0 wt%, zinc 1.2 wt%, and cadmium 0.1 wt%.

[0175] Waste white copper recycled copper is fed into a vertical furnace, heated to 1200℃, and argon gas is introduced at a rate of 10L / min (dew point -43℃) and a pressure of 0.2MPa. The furnace is held at this temperature for 2 hours at a rate of 2 tons / hour.

[0176] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had the following parameters: electrode spacing 10cm, current 100A / cm. 2 500 Hz, 50 μs, treatment for 4 hours; heat to 1150℃ and hold for 2 hours, with 0.4 wt% covering agent.

[0177] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.35 wt% purifying agent (MgB2:CeO2=3:2), which is preheated to 920℃ for 0.75 hours and added in 5 portions. The mixture is then heated to 1200℃ and stirred at 270 r / min for 3 hours. Finally, it is filtered using a filter with a pore size of 11 μm.

[0178] Heating to 1300℃ and 4Pa vacuum in a heat-insulating furnace for 2 hours, condensing to 200℃, and then purging with argon gas at 13L / min for 0.75 hours for homogenization.

[0179] Final impurity content: lead 0.022 wt%, bismuth 0.007 wt%, iron 0.014 wt%, nickel 0.012 wt%, zinc 0.014 wt%, cadmium 0.0007 wt%.

[0180] Example 20

[0181] Low-bismuth recycled copper, with initial impurities including: lead 0.5wt%, bismuth 0.1wt%, iron 0.3wt%, nickel 0.1wt%, zinc 1.0wt%, and cadmium 0.05wt%.

[0182] Low-bismuth recycled copper is fed into a vertical furnace, which is heated to 1100°C. Argon gas is introduced at a rate of 5 L / min (dew point -41°C) and a pressure of 0.1 MPa. The furnace is held at this temperature for 1 hour at a rate of 1 ton / hour.

[0183] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had the following parameters: electrode spacing 5cm, current 50A / cm. 2100 Hz, 10 μs, for 2 hours; heat to 1050℃ and hold for 1 hour, with 0.2 wt% covering agent.

[0184] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.1 wt% purifying agent (CaB6:La2O3=3:2), which is preheated to 800℃ for 0.5 hours and added in 3 portions. The mixture is then heated to 1100℃ and stirred at 100 r / min for 2 hours. Finally, it is filtered using a filter with a pore size of 5 μm.

[0185] Heat to 1200℃ and 10Pa vacuum in a heat-insulating furnace for 1 hour, condense to 100℃, and then introduce argon gas at 8L / min for 0.5 hours for homogenization.

[0186] Final impurity content: lead 0.035 wt%, bismuth 0.004 wt%, iron 0.02 wt%, nickel 0.005 wt%, zinc 0.02 wt%, cadmium 0.0005 wt%.

[0187] Example 21

[0188] High-lead recycled copper, with initial impurities including: lead 2.0 wt%, bismuth 0.5 wt%, iron 0.6 wt%, nickel 0.4 wt%, zinc 1.8 wt%, and cadmium 0.2 wt%.

[0189] High-lead recycled copper is fed into a vertical furnace, which is heated to 1250°C. Argon gas is introduced at a rate of 14 L / min (dew point -45°C) and a pressure of 0.25 MPa. The furnace is held at this temperature for 2.5 hours at a rate of 2.5 tons / hour.

[0190] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had the following parameters: electrode spacing 14 cm, current 140 A / cm², 800 Hz, 80 μs, and treatment time 5.5 hours; followed by heating to 1200℃ and holding for 2.5 hours, with a covering agent of 0.5 wt%.

[0191] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.45 wt% purifying agent (MgB2:CeO2=3:2), which is preheated to 960℃ for 0.85 hours and added in 5 portions. The mixture is then heated to 1250℃ and stirred at 300 r / min for 3.8 hours. Finally, it is filtered using a filter with a pore size of 15 μm.

[0192] Heating to 1350℃ and 2Pa vacuum in a heat-insulating furnace for 2.5 hours, condensing to 250℃, and then purging with argon gas at 17L / min for 0.85 hours for homogenization.

[0193] Final impurity content: lead 0.025 wt%, bismuth 0.006 wt%, iron 0.012 wt%, nickel 0.006 wt%, zinc 0.012 wt%, cadmium 0.0003 wt%.

[0194] Example 22

[0195] High-bismuth recycled copper, with initial impurities including: lead 0.8wt%, bismuth 1.0wt%, iron 0.5wt%, nickel 0.3wt%, zinc 1.5wt%, and cadmium 0.15wt%.

[0196] High-bismuth recycled copper is fed into a vertical furnace, which is heated to 1200°C. Argon gas is introduced at a rate of 12 L / min (dew point -44°C) and a pressure of 0.2 MPa. The furnace is held at this temperature for 2 hours at a rate of 2 tons / hour.

[0197] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had an electrode spacing of 13cm and a current of 130A / cm. 2 700 Hz, 70 μs, treatment for 5 hours; heat to 1180℃ and hold for 2 hours, with 0.45 wt% covering agent.

[0198] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.4 wt% purifying agent (CaB6:La2O3=3:2), which is preheated to 950℃ for 0.8 hours and added in 5 portions. The mixture is then heated to 1220℃ and stirred at 290 r / min for 3.5 hours. Finally, it is filtered using a filter with a pore size of 14 μm.

[0199] Heating to 1320℃ and 3Pa vacuum in a heat-insulating furnace for 2 hours, condensing to 230℃, and then purging with argon gas at 15L / min for 0.8 hours for homogenization.

[0200] Final impurity content: lead 0.022 wt%, bismuth 0.04 wt%, iron 0.015 wt%, nickel 0.008 wt%, zinc 0.015 wt%, cadmium 0.0006 wt%.

[0201] Example 23

[0202] The recycled copper contains the following impurities: lead 0.7 wt%, bismuth 0.35 wt%, iron 0.45 wt%, nickel 0.25 wt%, zinc 1.4 wt%, and cadmium 0.12 wt%.

[0203] The recycled copper containing impurities is fed into a vertical furnace, which is heated to 1180°C. Argon gas is introduced at a rate of 10 L / min (dew point -43°C) and a pressure of 0.18 MPa. The furnace is held at this temperature for 1.8 hours at a rate of 1.8 tons / hour.

[0204] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had the following parameters: electrode spacing 10cm, current 100A / cm. 2 500 Hz, 50 μs, treatment for 4 hours; heat to 1150℃ and hold for 1.8 hours, with 0.4 wt% covering agent.

[0205] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.3 wt% purifying agent (MgB2:CeO2=3:2), which is preheated to 900℃ for 0.7 hours and added in 4 portions. The mixture is then heated to 1180℃ and stirred at 260 r / min for 3 hours. Finally, it is filtered using a filter with a pore size of 11 μm.

[0206] Heating to 1280℃ and 5Pa vacuum in a heat-insulating furnace for 2 hours, condensing to 200℃, and then purging with argon gas at 13L / min for 0.7 hours for homogenization.

[0207] Final impurity content: lead 0.025 wt%, bismuth 0.008 wt%, iron 0.016 wt%, nickel 0.009 wt%, zinc 0.016 wt%, cadmium 0.0008 wt%.

[0208] Example 24

[0209] Low-zinc recycled copper, with initial impurities including: lead 0.6wt%, bismuth 0.3wt%, iron 0.4wt%, nickel 0.2wt%, zinc 0.8wt%, and cadmium 0.08wt%.

[0210] Low-zinc recycled copper is fed into a vertical shaft furnace, which is heated to 1150°C. Argon gas is introduced at a rate of 8 L / min (dew point -42°C) and a pressure of 0.15 MPa. The furnace is held at this temperature for 1.5 hours at a rate of 1.5 tons / hour.

[0211] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had the following parameters: electrode spacing 8cm, current 80A / cm. 2 300 Hz, 30 μs, treatment for 3 hours; heat to 1100℃ and hold for 1.5 hours, with 0.3 wt% covering agent.

[0212] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.25 wt% purifying agent (CaB6:CeO2=3:2), which is preheated to 870℃ for 0.6 hours and added in 4 portions. The mixture is then heated to 1170℃ and stirred at 220 r / min for 2.5 hours. Finally, it is filtered using a filter with a pore size of 9 μm.

[0213] Heating to 1260℃ and 7Pa vacuum in a heat-insulating furnace for 1.5 hours, condensing at 170℃, and then purging with argon gas at 10L / min for 0.6 hours for homogenization.

[0214] Final impurity content: lead 0.028 wt%, bismuth 0.009 wt%, iron 0.018 wt%, nickel 0.01 wt%, zinc 0.018 wt%, cadmium 0.001 wt%.

[0215] Example 25

[0216] High-purity recycled copper raw material, initial impurities include: lead 0.3wt%, bismuth 0.15wt%, iron 0.2wt%, nickel 0.1wt%, zinc 0.5wt%, and cadmium 0.05wt%.

[0217] High-purity recycled copper raw material is fed into a vertical furnace, which is heated to 1100℃. Argon gas is introduced at a rate of 6L / min (dew point -41℃) and a pressure of 0.12MPa. The furnace is held at this temperature for 1 hour at a rate of 1 ton / hour.

[0218] The first tilting refining furnace was used for impurity removal. The first tilting refining furnace had the following parameters: electrode spacing 6cm, current 60A / cm. 2 200 Hz, 20 μs, for 2 hours; then heat to 1060 ℃ and hold for 1 hour, with 0.2 wt% covering agent.

[0219] Then, a second tilting refining furnace is used to remove impurities. The second tilting refining furnace contains 0.15 wt% purifying agent (MgB2:La2O3=3:2), which is preheated to 820℃ for 0.5 hours and added in 3 portions. The mixture is then heated to 1120℃ and stirred at 150 r / min for 2 hours. Finally, it is filtered using a filter with a pore size of 6 μm.

[0220] Heat to 1220℃ and 9Pa vacuum in a heat-insulating furnace for 1 hour, condense to 120℃, and then introduce argon gas at 9L / min for 0.5 hours for homogenization.

[0221] Final impurity content: lead 0.03 wt%, bismuth 0.005 wt%, iron 0.01 wt%, nickel 0.005 wt%, zinc 0.01 wt%, cadmium 0.0005 wt%.

[0222] It should be noted that the ceramic filter is made of zirconium oxide (ZrO2 content ≥95%), adopts a foam ceramic structure, has a porosity of 60%-80%, and the filter pore size is selected according to the size of impurity particles, ranging from 5-15μm. Before filtration, it is preheated to 1000-1200℃ by an electric heating device at a preheating rate of 10-20℃ / min and held at that temperature for 0.5 hours to ensure that the temperature difference between the filter and the melt is ≤50℃, and the filtration pressure difference is controlled at 0.05-0.1MPa.

[0223] The inert gas is argon or nitrogen with a purity of ≥99.99%. The gas is purified (oxygen content ≤5ppm, water content ≤10ppm). During the homogenization stage of the holding furnace, the gas flow rate is adjusted to 8-20L / min according to the melt volume. The gas is supplied by a bottom-hole gas distribution device, and the bubble diameter is controlled at 5-20mm. During the homogenization process, the melt temperature is maintained at 1150-1250℃, and the temperature fluctuation is ≤±10℃.

[0224] The pulse current in the first tilting refining furnace uses graphite electrodes with an electrode density ≥1.8 g / cm³. 3Ash content ≤0.1%, electrode diameter 50-100mm, electrode spacing controlled at 5-15cm by mechanical adjustment device, spacing deviation ≤±0.5cm, electrode insertion depth into melt is 1.5-2 times the electrode diameter, pulse power supply output waveform is square wave, duty cycle 50%-70%.

[0225] The vertical shaft furnace is fed uniformly using a vibrating feeder. After crushing and screening, the particle size of the raw material is controlled at 50-200mm, with a maximum particle size to minimum particle size ratio of ≤4:1 and a raw material moisture content of ≤5%. The melting rate is adjusted to 1-3 tons / hour by adjusting the feed rate. The residence time of the melt in the vertical shaft furnace is controlled at 0.5-1.5 hours. A throttling device is installed at the outlet of the vertical shaft furnace to control the flow stability (fluctuation ≤±5%).

Claims

1. A method for deep purification of metallic impurities in recycled copper molten metal, characterized in that, Includes the following steps: S101, Vertical Furnace Pretreatment: Prepare recycled copper material, vertical furnace, first tilting refining furnace, second tilting refining furnace, zirconia ceramic filter, holding furnace and condensation device, control the feed particle size of recycled copper to 50-200mm, heat to 1100-1300℃, melting rate 1-3 tons / hour, argon protection, furnace pressure 0.1-0.3MPa, hold for 1-3 hours, use high temperature to initially volatilize 30%-40% of zinc and cadmium volatilized impurities, the melt is transferred to the first tilting refining furnace through the trough; S102, Segregation type impurity removal: In the first tilting refining furnace, a pulsed current is applied to the graphite electrode for 2-5 hours to promote the electromigration and aggregation of lead and bismuth; then the temperature is raised to 1050-1200℃, a covering agent is added and the temperature is maintained for 1-3 hours for gravity segregation, and the impurity enrichment layer is removed by slag removal. Removal of solid solution impurities: The melt is transferred to the second tilting refining furnace, and a preheated composite purifying agent is added in 3-5 batches; the mixture is stirred and reacted at 1100-1300℃ for 2-4 hours to generate insoluble compounds; the mixture is then filtered through a preheated zirconia ceramic filter to remove impurities. S103, final purification in the holding furnace: The melt enters the holding furnace, is heated to 1200-1400℃, evacuated to 1-10Pa, and held for 1-3 hours to volatilize residual volatile impurities, which are then recovered by the condenser; subsequently, inert gas is introduced and homogenized for 0.5-1 hours to obtain high-purity recycled copper melt.

2. The method for deep purification of metallic impurities in recycled copper melt according to claim 1, characterized in that: The argon flow rate ranges from 5 to 15 L / min.

3. The method for deep purification of metallic impurities in recycled copper melt according to claim 1, characterized in that: The spacing between the graphite electrodes on the first tilting furnace is 5-15 cm.

4. The method for deep purification of metallic impurities in recycled copper melt according to claim 1, characterized in that: The covering agent is composed of charcoal powder and borax in a ratio of 2:1, with a content of 0.2-0.5 wt%.

5. The method for deep purification of metallic impurities in recycled copper melt according to claim 1, characterized in that: The composite purifying agent is composed of boride and rare earth compounds in a ratio of 3:2, with a content of 0.1-0.5 wt%.

6. The method for deep purification of metallic impurities in recycled copper melt according to claim 1, characterized in that: The pulse current parameters applied to the graphite electrode are: 50-200 A / cm. 2 , 100-1000Hz, 10-100μs.

7. The method for deep purification of metallic impurities in recycled copper melt according to claim 1, characterized in that: When argon gas is introduced, the pressure inside the vertical furnace is maintained at 0.1-0.3MPa through the pressure regulating valve, with a pressure fluctuation range of ≤±0.02MPa, and the temperature gradient of the vertical furnace is controlled at 50-100℃ / m.

8. The method for deep purification of metallic impurities in recycled copper melt according to claim 1, characterized in that: The covering agent is added in two stages. The first stage adds 60%-70% of the total amount, and the remaining amount is added after 1 hour of heat preservation. The slag removal is controlled 30 minutes before the end of gravity segregation.

9. The method for deep purification of metallic impurities in recycled copper melt according to claim 1, characterized in that: Before use, the composite purifying agent is preheated in a muffle furnace at 800-1000℃ for 0.5-1 hours with a preheating rate of 5-10℃ / min. After cooling to 200-300℃ in the furnace, it is added to the second tilting refining furnace in 3-5 portions with an interval of 30-60 minutes between each addition. The addition location is in the melt vortex zone.

10. The method for deep purification of metallic impurities in recycled copper melt according to claim 1, characterized in that: The vertical shaft furnace is fed uniformly by a vibrating feeder. After crushing and screening, the particle size of the raw material is controlled at 50-200mm, the ratio of the maximum particle size to the minimum particle size is ≤4:1, the moisture content of the raw material is ≤5%, the melting rate is adjusted to 1-3 tons / hour by the feed rate, and the residence time of the melt in the vertical shaft furnace is controlled at 0.5-1.5 hours.

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