Short-flow process for efficiently preparing 5N-grade high-purity copper from copper electrolytic refining composite additive and scrap copper

Abstract

The invention discloses a copper electrolytic refining composite additive and a short-flow process for efficiently preparing 5N-grade high-purity copper from scrap copper. The copper electrolytic refining composite additive comprises a cathode crystallization fine control agent, a key impurity selective inhibitor and an electrolyte enhancer, the cathode crystallization fine control agent comprises hydroxyethyl cellulose and sodium 3, 3 '-dithiodipropane sulfonate, and the key impurity selective inhibitor is a modified chitosan derivative. The electrolyte enhancer comprises chloride ions and rare earth chloride. The short-flow process for efficiently preparing the 5N-grade high-purity copper from the scrap copper comprises the three steps of pretreatment and casting of the scrap copper, short-time surface oxidation and rapid cooling of an anode plate and electrolytic refining. By means of the method, the 5N-grade high-purity copper with the purity reaching 99.999% or above, the content of key impurities such as arsenic, antimony, bismuth and nickel being lower than 0.1 ppm and excellent surface physical performance can be stably produced.

Description

Technical Field

[0001] This invention relates to a copper electrolytic refining composite additive and a short-process technology for efficiently preparing 5N grade high-purity copper from waste copper using this copper electrolytic refining composite additive, belonging to the field of non-ferrous metal metallurgical technology. Background Technology

[0002] High-purity copper (5N and above) is a key basic material for strategic emerging industries such as 5G communication, integrated circuits, and new energy vehicles. At present, the production of high-purity copper relies heavily on the traditional long process of "mining-smelting-electrolysis" using copper concentrate as raw material, and faces multiple pressures such as resources, energy consumption, environment, and supply chain geopolitics.

[0003] Scrap copper, as a representative of "urban mining," is the most important secondary source of copper resources. The amount of scrap copper generated globally each year is enormous. Utilizing scrap copper, this "urban mine," to produce high-purity copper is an inevitable trend for achieving resource recycling and ensuring supply chain security, with significant economic, environmental, and social benefits.

[0004] However, scrap copper includes both high-grade and low-grade scrap copper. In addition, it contains trace amounts of positively charged impurities, negatively charged impurities, soluble impurities, and difficult-to-treat impurities, resulting in a complex composition. Impurities such as arsenic (As), antimony (Sb), bismuth (Bi), and nickel (Ni) are particularly difficult to remove, posing a significant challenge to its high-value utilization. Currently, there are two main routes for producing high-purity copper from scrap copper: one is the long process of "pyrometallurgical refining-electrolysis," which is energy-intensive, time-consuming, and has limited effectiveness in removing As, Sb, Bi, and Ni, making it difficult to consistently achieve 5N purity; the other is the "direct melting-electrolysis" method, which is prone to electrolyte contamination and cathode deposition deterioration due to high anode impurity content, resulting in low-grade products. Therefore, there is an urgent need in this field to develop a new technology for the resource utilization of scrap copper that can efficiently remove harmful impurities, has a short process, low cost, and can stably produce 5N high-purity copper.

[0005] Copper electrolytic refining is a crucial step in the process of preparing high-purity copper from scrap copper. Its purpose is to remove impurities from crude copper through electrolysis to obtain high-purity electrolytic copper. In the copper electrolytic refining process, the use of additives plays a vital role in both the electrolysis process and product quality. Currently, the industry commonly uses bone glue, thiourea, hydrochloric acid, and gelatin as copper electrolytic refining additives. However, the current copper electrolytic refining additive system is insufficient to meet the quality requirements of 5N grade high-purity copper. Therefore, there is an urgent need in this field to develop a composite copper electrolytic refining additive that can meet the quality requirements of 5N grade high-purity copper. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, the purpose of this invention is to provide a copper electrolytic refining composite additive and a short-process technology for efficiently preparing 5N-grade high-purity copper from waste copper using this copper electrolytic refining composite additive.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: A copper electrolytic refining composite additive includes a cathode crystallization control agent, a key impurity selectivity inhibitor, and an electrolyte enhancer. The cathode crystallization control agent includes hydroxyethyl cellulose and sodium polydithiopropane sulfonate. The key impurity selectivity inhibitor is a modified chitosan derivative. The electrolyte enhancer includes chloride ions and rare earth chlorides.

[0008] In one embodiment, the mass ratio of hydroxyethyl cellulose to sodium polydisulfide sulfonate in the cathode crystallization control agent is (5:1) to (10:1). Hydroxyethyl cellulose and sodium polydisulfide sulfonate work together to regulate the electrocrystallization process of copper, thereby obtaining a smooth, dense, dendrite-free cathode copper.

[0009] In one embodiment, the modified chitosan derivative is at least one of carboxymethyl chitosan and hydroxypropyltrimethylammonium chloride chitosan. When both carboxymethyl chitosan and hydroxypropyltrimethylammonium chloride chitosan are selected, they can be compounded in any ratio, for example, the mass ratio of carboxymethyl chitosan to hydroxypropyltrimethylammonium chloride chitosan is 1:99-99:1. This type of modified chitosan derivative can selectively adsorb arsenic (As), antimony (Sb), and bismuth (especially BiO) in the electrolyte onto the cathode surface through molecular selective adsorption. + The complexing or shielding effect of nickel (Ni) significantly increases the overpotential of the discharge of the above-mentioned impurity ions, thereby effectively suppressing their co-deposition on the cathode, thus ensuring that the final copper product reaches 5N (99.999%) purity, and ensuring that the content of each single impurity element of arsenic (As), antimony (Sb), bismuth (Bi), and nickel (Ni) in the copper product is less than 0.1 ppm.

[0010] In one embodiment, the electrolyte enhancer contains chloride ions (Cl... - The rare earth chloride is provided by hydrochloric acid or sodium chloride, and is at least one of cerium chloride and lanthanum chloride. Chloride ions in the electrolyte enhancer can be used to optimize anodic dissolution and cathodic deposition, while rare earth ions can improve the properties of anodic slime and catalyze the oxidation and precipitation of some impurities.

[0011] In one embodiment, when the copper electrolytic refining composite additive is used in copper electrolytic refining, the working concentration in the electrolyte is: hydroxyethyl cellulose 10~50 mg / L, sodium polydithiopropane sulfonate 1~10 mg / L, key impurity selective inhibitor 5~30 mg / L, chloride ion 30~60 mg / L, and rare earth chloride 2~15 mg / L.

[0012] A short-process technology for efficiently preparing 5N grade high-purity copper from scrap copper includes the following steps: 1) Pretreatment and casting of scrap copper: The scrap copper raw material is cleaned, and the total concentration of impurities such as nickel (Ni), arsenic (As), antimony (Sb), and bismuth (Bi) in the scrap copper raw material is required to be ≤1.6 wt%. Then, the scrap copper raw material is smelted into copper liquid under a protective atmosphere. The smelted copper liquid is then refined and filtered in sequence, and finally cast into anode plates. 2) Short-term surface oxidation and rapid cooling of the anode plate: The anode plate obtained in step 1) is subjected to short-term surface oxidation treatment at a temperature of 650-800℃ in an oxygen-containing atmosphere for 5-30 minutes, and then rapidly cooled to form a functionalized oxide layer on the surface of the anode plate. 3) Electrolytic refining: The copper electrolytic refining composite additive is added to the electrolyte, and electrolytic refining is carried out in the electrolytic cell using the anode plate treated in step 2) as the anode. The resulting cathode copper is the required 5N grade high-purity copper.

[0013] In one embodiment, in step 1), the scrap copper raw material is scrap copper of a single grade or a mixture of scrap copper of different grades. When the scrap copper raw material is a mixture of scrap copper, the scrap copper of different grades is first sorted and cleaned, and then the scrap copper of different grades is mixed to ensure that the total concentration of impurities such as nickel (Ni), arsenic (As), antimony (Sb), and bismuth (Bi) in the mixed scrap copper raw material is ≤1.6 wt%.

[0014] In one implementation scheme, in step 1), the melting temperature is 1280~1320℃.

[0015] In one embodiment, in step 1), the concentration of each single element impurity in the scrap copper raw material is limited to: Ni≤1.4wt%, As≤0.12wt%, Sb≤0.15wt%, Bi≤0.08wt%.

[0016] In one embodiment, in step 1), the refining refers to injecting a composite refining agent carried by an inert gas into the molten copper obtained by smelting. The composite refining agent is composed of an alkaline flux and an oxidant in a mass ratio of 1:(0.1~0.5).

[0017] In a preferred embodiment, the alkaline flux is an alkali metal carbonate, wherein the alkali metal carbonate is at least one of sodium carbonate and potassium carbonate, and when sodium carbonate and potassium carbonate are used simultaneously, they can be mixed in any proportion; the oxidant is an alkali metal nitrate, wherein the alkali metal nitrate is at least one of sodium nitrate and potassium nitrate, and when sodium nitrate and potassium nitrate are used simultaneously, they can be mixed in any proportion.

[0018] In a preferred embodiment, the amount of the composite refining agent added is 1 to 1.5% of the mass of the molten copper.

[0019] In one embodiment, step 1), the melt filtration refers to continuously passing molten copper through at least one stage of a foam ceramic filter with a porosity of 20-60 PPI.

[0020] In one embodiment, in step 2), the volume fraction of oxygen in the oxygen-containing atmosphere is 20-22%, for example, the oxygen-containing atmosphere is air, and the volume fraction of oxygen in air is about 21%.

[0021] In one implementation scheme, step 2), the rapid cooling method used is water mist cooling.

[0022] In one embodiment, step 2), the rapid cooling refers to reducing the surface temperature of the anode plate from 650-800°C after oxidation treatment to a stable 200-400°C within 10 minutes at a cooling rate of 50-65°C / min. Under this cooling condition, a dense functionalized oxide layer with a thickness of 5-20 micrometers can be formed on the surface of the anode plate. This oxide layer can effectively promote the uniform dissolution of the anode during subsequent electrolysis, delay passivation, and preferentially oxidize and fix impurities such as Bi near the anode surface, preventing them from dissolving into the electrolyte prematurely. This provides a more relaxed working environment for the composite additive, allowing it to deeply capture impurity ions, thereby achieving efficient blocking of difficult-to-remove impurities such as Bi.

[0023] In one embodiment, in step 3), the electrolyte used in the electrolytic refining process is a copper sulfate-sulfuric acid system, wherein the copper ion concentration is 40-50 g / L, the sulfuric acid concentration is 180-220 g / L, the electrolysis temperature is 55-65℃, and the current density is 200-280 A / m. 2 .

[0024] In one implementation scheme, in step 3), during the electrolytic refining process, 7-10% of the electrolyte is diverted for circulation purification. Specifically, 7-10% of the electrolyte is diverted from the electrolysis system, purified by a purification device containing sulfonic acid adsorption resin, and then returned to the electrolysis system.

[0025] A high-purity copper prepared using the aforementioned short-process technology, wherein the copper purity is not less than 99.999%, and the content of each individual impurity element, such as arsenic, antimony, bismuth, and nickel, is less than 0.1 ppm.

[0026] Compared with the prior art, the present invention has the following significant advantages: 1. This invention combines a cathode crystallization control agent, a key impurity selective inhibitor, and an electrolyte enhancer to form a composite additive that can be used for copper electrolytic refining. In the process of preparing 5N grade high-purity copper from scrap copper, the anode plate is subjected to short-term surface oxidation and rapid cooling before electrolytic refining, so that a functionalized oxide layer is formed on the surface of the anode plate. This functionalized oxide layer and the composite additive work synergistically to achieve efficient inhibition of the most difficult-to-remove impurities such as As, Sb, and Bi, thereby stably producing 5N grade high-purity copper with a purity of over 99.999% and the content of each key impurity below 0.1 ppm. 2. The process for efficiently preparing 5N grade high-purity copper from scrap copper provided by this invention is a short process of "pretreatment and casting of scrap copper - surface modification of anode plate - electrolytic refining". Compared with the traditional pyrometallurgical refining process, it significantly shortens the process flow, improves production efficiency, and reduces energy consumption and costs. 3. The composite additive provided by this invention is used in copper electrolytic refining. It not only achieves efficient suppression of the most difficult-to-remove impurities such as As, Sb, and Bi, but also ensures that the obtained cathode copper product has a smooth and dense surface, free from defects such as dendrites and lumps, reduces impurity entrainment, and improves the physical quality of the product. 4. This invention prepares 5N grade high-purity copper from scrap copper, which can process complex scrap copper raw materials of different grades, broadens the source of raw materials, and realizes the recycling of resources. Attached Figure Description

[0027] Figure 1 Photograph of the anode plate prepared in Example 1; Figure 2 Photograph of the high-purity cathode copper prepared in Example 1; Figure 3 Photograph of the high-purity cathode copper prepared in Example 2; Figure 4 Photograph of the high-purity cathode copper prepared in Example 3; Figure 5 Photograph of the high-purity cathode copper prepared in Example 4; Figure 6 A photograph of the high-purity cathode copper prepared in Example 5 after plastic encapsulation; Figure 7 Photograph of the cathode copper prepared for Comparative Example 1; Figure 8 Photograph of the cathode copper prepared for Comparative Example 2; Figure 9 Photograph of the cathode copper prepared for Comparative Example 3; Figure 10 Photograph of the cathode copper prepared for Comparative Example 4; Figure 11 Photograph of the cathode copper prepared for Comparative Example 5; Figure 12 Photograph of the cathode copper prepared for Comparative Example 6; Figure 13 Photograph of the cathode copper prepared for Comparative Example 7; Figure 14 Photograph of the cathode copper prepared for Comparative Example 8. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail and completely below with reference to the embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer.

[0029] Example 1 This embodiment provides a short-process technology for efficiently preparing 5N grade high-purity copper from scrap copper, including the following steps: 1) Pretreatment and casting of scrap copper: After mechanically separating scrap copper #1 (mainly copper wire and copper pipe with low bismuth content) and scrap copper #2 (mainly cables and copper sheaths with high Sb and As content), the scrap copper is cleaned with NaOH alkaline solution at 80℃ to remove grease, plastic and other non-metallic inclusions from the surface. Then, the cleaned scrap copper is blended in a ratio of 85wt% scrap copper #1 and 15wt% scrap copper #2. The impurity concentrations of nickel (Ni), arsenic (As), antimony (Sb) and bismuth (Bi) in the blended raw material are as follows: Ni: 1.2 wt%, As: 0.13 wt%, Sb: 0.11 wt%, Bi: 0.06 wt%.

[0030] Then, under an argon atmosphere, the raw materials were melted into molten copper at 1280℃. A composite refining agent carried by nitrogen (Na2CO3:NaNO3 mass ratio of 1:0.25, added at 1.0% of the molten copper mass) was then injected into the molten copper for refining. The molten copper was then filtered through 30 PPI and 50 PPI foam ceramic filters in sequence, and finally cast into an anode plate. 2) Short-term surface oxidation and rapid cooling of the anode plate: The anode plate obtained in step 1) is subjected to short-term surface oxidation treatment in air at 750°C for 20 minutes, and then rapidly cooled by water mist cooling, so that the surface temperature drops to 400°C within 6 minutes (the corresponding cooling rate is about 58°C / minute), so that a functionalized oxide layer is formed on the surface of the anode plate. 3) Electrolytic Refining: A copper electrolytic refining composite additive is added to the electrolyte. Electrolytic refining is performed in an electrolytic cell using the anode plate treated in step 2) as the anode and a stainless steel plate as the cathode. The electrolyte is a copper sulfate-sulfuric acid system, with a copper ion concentration of 45 g / L and a sulfuric acid concentration of 200 g / L. The electrolysis temperature is 60℃, and the current density is 250 A / m³. 2 The composite additive consists of: hydroxyethyl cellulose (HEC) 25 mg / L, sodium polydithiopropane sulfonate (SPS) 3 mg / L, carboxymethyl chitosan 10 mg / L, Cl - (Provided by HCl) 35 mg / L, CeCl 35 mg / L; During the electrolytic refining process, 7% of the electrolyte is diverted from the electrolysis system, purified by a purification device containing sulfonic acid adsorption resin, and then returned to the electrolysis system. Electrolytic refining was carried out for five days to obtain cathode copper. The obtained cathode copper was analyzed by GD-MS, and the analysis results are shown in Table 1.

[0031] Table 1. GD-MS analysis results of the cathode copper prepared in Example 1

[0032] As shown in Table 1, the cathode copper prepared in this embodiment has a copper purity of 99.999947%, a Ni content of less than 0.001 ppm, an As content of less than 0.01 ppm, a Sb content of 0.006 ppm, and a Bi content of 0.02 ppm. Therefore, the cathode copper prepared in this embodiment is a 5N grade high-purity copper with a purity of over 99.999% and the contents of each key impurity (Ni, As, Sb, and Bi) of less than 0.1 ppm.

[0033] Figure 1 This is a photograph of the anode plate prepared in this embodiment. Figure 1 It is evident that the formed anode plate has a dense structure and uniform composition. Figure 2 This is a photograph of the cathode copper prepared in this embodiment, from... Figure 2 It is evident that the cathode copper has a smooth, dense surface, a bright metallic red color, and is free of defects such as dendrites and nodules, exhibiting excellent physical quality.

[0034] Combining Table 1 and Figure 2It can be seen that the cathode copper prepared in this embodiment is a 5N grade high-purity copper with excellent physical quality, smooth surface, and no defects.

[0035] Example 2 This embodiment provides a short-process technology for efficiently preparing 5N grade high-purity copper from scrap copper, including the following steps: 1) Pretreatment and casting of scrap copper: Scrap copper #1 (mainly copper wire and copper pipe) and scrap copper #2 (mainly cables and copper sheaths, with high Sb and As content) are mechanically sorted and then cleaned with NaOH alkaline solution at 80℃. The cleaned scrap copper is then blended at a ratio of 85 wt% scrap copper #1 and 15 wt% scrap copper #2. The impurity concentrations of nickel (Ni), arsenic (As), antimony (Sb), and bismuth (Bi) in the blended raw material are as follows: Ni: 1.2 wt%, As: 0.12 wt%, Sb: 0.15 wt%, Bi: 0.03 wt%. Then, under an argon atmosphere, the raw materials were melted into molten copper at 1300℃. A composite refining agent carried by nitrogen (Na2CO3:NaNO3 mass ratio of 1:0.4, added at 1.2% of the molten copper mass) was then injected into the molten copper for refining. The molten copper was then filtered through 30 PPI and 50 PPI foam ceramic filters in sequence, and finally cast into an anode plate. 2) Short-term surface oxidation and rapid cooling of the anode plate: The anode plate obtained in step 1) is subjected to short-term surface oxidation treatment in air at 750°C for 10 minutes, and then rapidly cooled by water mist cooling, so that the surface temperature drops to 400°C within 6 minutes (the corresponding cooling rate is about 58°C / minute), so that a functionalized oxide layer is formed on the surface of the anode plate. 3) Electrolytic Refining: A copper electrolytic refining composite additive is added to the electrolyte. Electrolytic refining is performed in an electrolytic cell using the anode plate treated in step 2) as the anode and a stainless steel plate as the cathode. The electrolyte is a copper sulfate-sulfuric acid system, with a copper ion concentration of 45 g / L and a sulfuric acid concentration of 200 g / L. The electrolysis temperature is 60℃, and the current density is 250 A / m³. 2 The composite additive consists of: hydroxyethyl cellulose (HEC) 40 mg / L, sodium polydithiopropane sulfonate (SPS) 5 mg / L, carboxymethyl chitosan 25 mg / L, Cl - (Provided by HCl) 50 mg / L, CeCl3 10 mg / L; During the electrolytic refining process, 10% of the electrolyte is diverted from the electrolysis system, purified by a purification device containing sulfonic acid adsorption resin, and then returned to the electrolysis system. Electrolytic refining was carried out for five days to obtain cathode copper. The obtained cathode copper was analyzed by GD-MS, and the analysis results are shown in Table 2.

[0036] Table 2. GD-MS analysis results of the cathode copper prepared in Example 2

[0037] As can be seen from Table 2, the cathode copper prepared in this embodiment has a copper purity of 99.99990%, a Ni content of less than 0.001 ppm, an As content of less than 0.01 ppm, a Sb content of 0.04 ppm, and a Bi content of 0.04 ppm. Therefore, the cathode copper prepared in this embodiment is a 5N grade high-purity copper with a purity of over 99.999% and the contents of each key impurity (Ni, As, Sb, and Bi) of less than 0.1 ppm.

[0038] Figure 3 This is a photograph of the cathode copper prepared in this embodiment, from... Figure 3 It is evident that the cathode copper has a smooth, dense surface, a bright metallic red color, and is free of defects such as dendrites and nodules, exhibiting excellent physical quality.

[0039] Combine Table 2 and Figure 3 It can be seen that the cathode copper prepared in this embodiment is a 5N grade high-purity copper with excellent physical quality, smooth surface, and no defects.

[0040] Example 3 This embodiment provides a short-process technology for efficiently preparing 5N grade high-purity copper from scrap copper, including the following steps: 1) Pretreatment and casting of scrap copper: High-nickel electronic scrap copper is used as raw material. After mechanical sorting, it is cleaned with NaOH alkaline solution at 80℃. The impurity concentrations of nickel (Ni), arsenic (As), antimony (Sb), and bismuth (Bi) in the raw material are 1.2 wt%, As: 0.07 wt%, Sb: 0.09 wt%, and Bi: 0.08 wt%.

[0041] Then, under an argon atmosphere, the raw materials are melted into molten copper at 1320℃. A composite refining agent carried by nitrogen (Na2CO3:NaNO3 mass ratio of 1:0.3, added at 1.5% of the mass of molten copper) is then injected into the molten copper for refining. The molten copper is then filtered through 30 PPI and 50 PPI foam ceramic filters in sequence, and finally cast into an anode plate. 2) Short-term surface oxidation and rapid cooling of the anode plate: The anode plate obtained in step 1) is subjected to short-term surface oxidation treatment in air at a temperature of 680°C for 20 minutes, and then rapidly cooled by water mist cooling to reduce the surface temperature to 400°C within 5 minutes (the corresponding cooling rate is about 56°C / minute), so that a functionalized oxide layer is formed on the surface of the anode plate. 3) Electrolytic Refining: A copper electrolytic refining composite additive is added to the electrolyte. Electrolytic refining is performed in an electrolytic cell using the anode plate treated in step 2) as the anode and a stainless steel plate as the cathode. The electrolyte is a copper sulfate-sulfuric acid system, with a copper ion concentration of 45 g / L and a sulfuric acid concentration of 200 g / L. The electrolysis temperature is 60℃, and the current density is 250 A / m³. 2 The composite additive consists of: hydroxyethyl cellulose (HEC) 50 mg / L, sodium polydithiopropane sulfonate (SPS) 4 mg / L, carboxymethyl chitosan 20 mg / L, Cl - (Provided by HCl) 45 mg / L, CeCl3 12 mg / L; During the electrolytic refining process, 9% of the electrolyte is diverted from the electrolysis system, purified by a purification device containing sulfonic acid adsorption resin, and then returned to the electrolysis system. Electrolytic refining was carried out for five days to obtain cathode copper. The obtained cathode copper was analyzed by GD-MS, and the analysis results are shown in Table 3.

[0042] Table 3. GD-MS analysis results of the cathode copper prepared in Example 3

[0043] As shown in Table 3, the cathode copper prepared in this embodiment has a copper purity of 99.999969%, a Ni content of less than 0.001 ppm, an As content of less than 0.01 ppm, a Sb content of less than 0.005 ppm, and a Bi content of 0.002 ppm. Therefore, the cathode copper prepared in this embodiment is a 5N grade high-purity copper with a purity of over 99.999% and the contents of each key impurity (Ni, As, Sb, and Bi) of less than 0.1 ppm.

[0044] Figure 4 This is a photograph of the cathode copper prepared in this embodiment, from... Figure 4 It is evident that the cathode copper has a smooth, dense surface, a bright metallic red color, and is free of defects such as dendrites and nodules, exhibiting excellent physical quality.

[0045] Combined with Table 3 and Figure 4 It can be seen that the cathode copper prepared in this embodiment is a 5N grade high-purity copper with excellent physical quality, smooth surface, and no defects.

[0046] Example 4 This embodiment provides a short-process technology for efficiently preparing 5N-grade high-purity copper from scrap copper. The difference from Example 1 is that in step 3), "carboxymethyl chitosan" is replaced with "hydroxypropyltrimethylammonium chloride chitosan" in the composite additive; the rest is the same as in Example 1. GD-MS analysis of the prepared cathode copper showed that the product purity reached 99.99932%, and the contents of key impurities such as Ni, As, Sb, and Bi were all below 0.01 ppm, classifying it as 5N-grade high-purity copper.

[0047] Figure 5 This is a photograph of the cathode copper prepared in this embodiment, from... Figure 5 As can be seen, the cathode copper surface is smooth, dense, and has a bright metallic red color. It is free of defects such as dendrites, protrusions, or cracks, and its appearance is highly consistent with that of the cathode copper in Example 1. Only the edges have no obvious color difference, and its physical quality meets the appearance requirements of 5N high-purity copper.

[0048] As can be seen from Examples 1 and 4, in the composite additive, the key impurity selective inhibitors are carboxymethyl chitosan or hydroxypropyltrimethylammonium chloride chitosan, both of which can enable the prepared cathode copper to meet the requirements of 5N high-purity copper.

[0049] Example 5 This embodiment provides a short-process technology for the efficient preparation of 5N grade high-purity copper from waste copper. The difference from Embodiment 2 is that in step 3), "carboxymethyl chitosan" is replaced with "a compound of carboxymethyl chitosan and hydroxypropyltrimethylammonium chloride chitosan in a mass ratio of 1:1", while the rest is the same as in Embodiment 2.

[0050] Figure 6 This is a photograph of the cathode copper after molding, prepared in this embodiment. Figure 6 As can be seen, the cathode copper has a smooth and dense surface, a uniform bright red metallic color, no impurities, spots or dendrite defects, and no oxidation or darkening at the edges. Its physical quality meets the appearance requirements of 5N high-purity copper, and its appearance is superior to that of the cathode copper in Example 2.

[0051] As can be seen from Examples 1, 2, 4 and 5, the key impurity selective inhibitors are carboxymethyl chitosan, hydroxypropyltrimethylammonium chloride chitosan or a mixture of the two, which can enable the prepared cathode copper to meet the requirements of 5N high-purity copper, and the cathode copper prepared by the mixture of the two has a better appearance.

[0052] Comparative Example 1 This comparative example provides a process for preparing high-purity copper from scrap copper, including the following steps: 1) Same as step 1) of Example 1. 2) The difference from step 2) of Example 1 is that after the anode plate is cast, it is placed directly in an argon atmosphere for natural cooling at a cooling rate of about 15-20 ℃ / min. It takes about 40-60 minutes to drop from the casting plate temperature (about 1200℃) to 200-400℃. No functionalized oxide layer is formed on the surface of the anode plate. 3) Same as step 3 in Example 1.

[0053] Figure 7 This is a photograph of the cathode copper prepared in this comparative example, from... Figure 7 It is evident that the cathode copper prepared in this embodiment has poor surface smoothness, lacks metallic luster, and exhibits poor physical quality.

[0054] As can be seen from Example 1 and Comparative Example 1, in the process of preparing cathode copper, after the anode plate is cast, the short-time surface oxidation treatment is cancelled and the plate is directly cooled. Furthermore, the cooling method and cooling rate used are different from those in Example 1. The cooling rate is too slow, resulting in the absence of a functional oxide layer on the surface of the prepared anode plate. Consequently, the physical quality of the prepared cathode copper is poor. This indicates that "short-time surface oxidation and rapid cooling of the anode plate to form a functional oxide layer on the surface of the anode plate" has a significant impact on the physical quality of the prepared cathode copper product.

[0055] Comparative Example 2 This comparative example provides a process for preparing high-purity copper from scrap copper, including the following steps: 1) Same as step 1) of Example 1. 2) The difference from step 2) of Example 1 is that the cooling method and cooling rate are different after the anode plate is subjected to short-term surface oxidation: natural air cooling is used instead of water mist forced cooling for the oxidized anode plate, the cooling rate is only 25-30℃ / minute, and it takes about 20-24 minutes for the surface temperature of the anode plate to drop from 750℃ to 200-400℃. 3) Same as step 3 in Example 1.

[0056] Figure 8 This is a photograph of the cathode copper prepared in this comparative example, from... Figure 8 As can be seen, the cathode copper prepared in this embodiment has a small amount of fine dendrites and local depressions on its surface, the metallic luster is slightly dim, and the overall flatness is not as good as that of the embodiment 1.

[0057] As can be seen from Example 1 and Comparative Example 2, the cooling method and cooling rate have a significant impact on the physical quality of the final product during the preparation of cathode copper, and the cooling rate cannot be too slow.

[0058] Comparative Example 3 This comparative example provides a process for preparing high-purity copper from scrap copper, including the following steps: 1) Same as step 1) of Example 1. 2) Same as step 2) in Example 1. 3) The difference from step 3) of Example 1 is that the composite additive system used is different: a traditional composite additive system is used instead of the composite additive in Example 1. The specific composition is: gelatin 50 mg / L, thiourea 20 mg / L, sodium chloride 35 mg / L, casein 30 mg / L, and the rest is the same as in Example 1.

[0059] Figure 9 This is a photograph of the cathode copper prepared in this comparative example. Figure 9 As can be seen, the cathode copper prepared in this comparative example has obvious "cauliflower-like" protrusions on its surface, with local dendrite growth, poor surface smoothness, dark purplish-red color, and no metallic luster.

[0060] In addition, GD-MS analysis was performed on the cathode copper prepared in this comparative example. The analysis results showed that the purity of the cathode copper product was 4N grade (99.99683%), which did not meet the 5N standard. Furthermore, the content of key impurities such as Ni, As, Sb, and Bi was 50-80 times that of Example 1.

[0061] As can be seen from Example 1 and Comparative Example 3, the composition of the composite additives added to the electrolyte during the preparation of cathode copper has a significant impact on the purity and surface quality of the cathode copper product. The composite additive system used in this comparative example lacks the hydroxyethyl cellulose, sodium polydisulfide dipropane sulfonate, and modified chitosan derivatives found in Example 1. This results in a weak selective inhibition ability of the composite additive against positively charged impurities and an inability to effectively control the cathode crystal morphology, leading to poor surface quality and purity of the prepared cathode copper.

[0062] Comparative Example 4 This comparative example provides a process for preparing high-purity copper from scrap copper, including the following steps: 1) Same as step 1) of Example 1. 2) Same as step 2) in Example 1. 3) The difference from step 3) of Example 1 is that the composite additive system used is different: the cathode crystallization control agent "hydroxyethyl cellulose (HEC) 25 mg / L + sodium polydisulfide dipropane sulfonate (SPS) 3 mg / L" in the composite additive of Example 1 is replaced with the traditional "gelatin 40 mg / L + casein 30 mg / L", and the rest is the same as in Example 1.

[0063] Figure 10 The image shows the cathode copper prepared in this comparative example. Figure 10 As can be seen, although the cathode copper prepared in this embodiment has no obvious dendrites, it has fine cracks and local depressions. The surface smoothness is much lower than that of Example 1, and the metallic luster is dull.

[0064] As can be seen from Example 1 and Comparative Example 4, the composition of the composite additives added to the electrolyte during the preparation of cathode copper has a significant impact on the surface quality of the cathode copper product. Changes in the cathode crystallization control agent in the composite additives will lead to a deterioration in the surface quality of the prepared cathode copper.

[0065] Comparative Example 5 This comparative example provides a process for preparing high-purity copper from scrap copper, including the following steps: 1) Same as step 1) of Example 1. 2) Same as step 2) in Example 1. 3) The difference from step 3) of Example 1 is that the composite additive system used is different: the key impurity selective inhibitor in the composite additive of Example 1 is replaced with the traditional "thiourea 15 mg / L" instead of "carboxymethyl chitosan". The rest is the same as in Example 1.

[0066] Figure 11 The image shows the cathode copper prepared in this comparative example. Figure 11 As can be seen, the cathode copper prepared in this comparative example has local black spots on its surface, uneven surface luster, and a small number of fine dendrites.

[0067] As can be seen from Example 1 and Comparative Example 5, the composition of the composite additives added to the electrolyte during the preparation of cathode copper has a significant impact on the surface quality of the cathode copper product. Changes in the selective inhibitors of key impurities in the composite additives will lead to a deterioration in the surface quality of the prepared cathode copper.

[0068] Comparative Example 6 This comparative example provides a process for preparing high-purity copper from scrap copper, including the following steps: 1) Same as step 1) of Example 1. 2) Same as step 2) in Example 1. 3) The difference from step 3) of Example 1 is that the composite additive system used is different: the key impurity selective inhibitor in the composite additive of Example 1 is replaced with "carboxymethyl chitosan 10 mg / L" and the rest is the same as Example 1.

[0069] Figure 12 The image shows the cathode copper prepared in this comparative example. Figure 12 As can be seen, the cathode copper prepared in this comparative example has no obvious dendrites on its surface, but there are local "foggy" dark areas, and the gloss is lower than that of Example 1.

[0070] In addition, GD-MS analysis was performed on the cathode copper prepared in this comparative example. The analysis results showed that the purity of the cathode copper product was close to 5N grade (99.99921%), but the content of key impurities such as Ni, As, Sb and Bi in the product was much higher than that in Example 1.

[0071] As can be seen from Example 1 and Comparative Example 6, the composition of the composite additives added to the electrolyte during the preparation of cathode copper has a significant impact on the surface quality of the cathode copper product. Simply replacing the modified chitosan derivative (carboxymethyl chitosan) in the composite additive with ordinary chitosan leads to a deterioration in the surface quality and purity of the cathode copper. This may be because the modified chitosan derivative introduces polar groups compared to ordinary chitosan, enhancing its affinity for BiO. + The complexing and shielding capabilities of impurity ions effectively improve the surface quality and purity of the cathode copper.

[0072] Comparative Example 7 This comparative example provides a process for preparing high-purity copper from scrap copper, including the following steps: 1) Same as step 1) of Example 1. 2) Same as step 2) in Example 1. 3) The difference from step 3) of Example 1 is that the composite additive system used is different: the electrolyte enhancer in the composite additive of Example 1 is changed from "Cl" - Replace "35 mg / L + CeCl 35 mg / L" with "Cl" - "35 mg / L", the rest is the same as in Example 1.

[0073] Figure 13 The image shows the cathode copper prepared in this comparative example. Figure 13 As can be seen, the surface of the cathode copper prepared in this comparative example is generally smooth, but there are a small number of "burr-like" protruding impurities attached to the edges.

[0074] In addition, GD-MS analysis was performed on the cathode copper prepared in this comparative example. The results showed that although the purity of the cathode copper product reached 5N level (99.99968%), the content of impurities such as Ni, As, Sb, and Bi was higher than that in Example 1.

[0075] As can be seen from Example 1 and Comparative Example 7, the composition of the composite additives added to the electrolyte during the preparation of cathode copper has a significant impact on the surface quality of the cathode copper product. Removing only the rare earth chlorides from the composite additives will lead to a deterioration in the surface quality and purity of the cathode copper. This may be because: rare earth chlorides can improve the structure of the anode mud, effectively preventing the phenomenon of impurities adhering to the edge of the cathode copper due to the suspension of the anode mud. In addition, rare earth chlorides can also catalyze the oxidation of some impurities into high-valence precipitates, thereby further improving the impurity removal efficiency and ultimately effectively improving the surface quality and purity of the cathode copper product.

[0076] As can be seen from Example 1 and Comparative Examples 3-7, the composition of the composite additives added to the electrolyte during the preparation of cathode copper has a significant impact on the surface quality of the cathode copper product. The components of the composite additives added to the electrolyte have a synergistic effect. Changing any component in the composite additives will destroy the synergistic effect between the components in the additives, thereby leading to a deterioration in the surface quality and purity of the cathode copper.

[0077] Comparative Example 8 This comparative example provides a process for preparing high-purity copper from scrap copper, including the following steps: 1) Same as step 1) of Example 1. 2) The difference from step 2) of Example 1 is that: after the anode plate is cast, it is placed directly in an argon atmosphere for natural cooling at a cooling rate of about 18 ℃ / min. It takes about 50 minutes to reduce the temperature of the casting plate from 1200℃ to 200-400℃. No functional oxide layer is formed on the surface of the anode plate, and it is only a conventional cast surface. 2) The difference from step 3) of Example 1 is that the composite additive system used is different: the composite additive in Example 1 is replaced with “45 mg / L gelatin and 35 mg / L sodium chloride”, and the cathode crystallization control agent (HEC, SPS), key impurity selectivity inhibitor (carboxymethyl chitosan) and rare earth chloride (CeCl3) electrolyte enhancer in Example 1 are not used. The rest is the same as in Example 1.

[0078] Figure 14 The image shows the cathode copper prepared in this comparative example. Figure 14 As can be seen, the cathode copper prepared in this comparative example has a severely degraded surface with a large number of "needle dendrites" and "blocky protrusions", accompanied by black impurity spots in some areas. The surface is rough and powder is easily detached. The color is dark brown and has no metallic luster, which does not meet the appearance requirements of high-purity copper at all.

[0079] In addition, GD-MS analysis of the cathode copper prepared in this comparative example showed that the purity of the product was only 99.98765%, which is far from the 5N grade standard.

[0080] As can be seen from Example 1 and Comparative Example 8, in the process of preparing cathode copper, the "short-time surface oxidation and rapid cooling of the anode plate" treatment used in step 2) of Example 1 results in a synergistic effect between the functionalized oxide layer formed on the surface of the anode plate and the composite additive used in the copper electrolytic refining in step 3). The two work together to achieve efficient suppression of the most difficult-to-remove impurities such as As, Sb, and Bi, thereby stably producing 5N-grade high-purity copper with a purity of over 99.999%, a content of each key impurity below 0.1 ppm, and excellent surface physical properties. In contrast, in Comparative Example 8, there is no functionalized oxide layer on the surface of the anode plate in step 2), resulting in extremely uneven anode dissolution. This leads to large fluctuations in the copper ion concentration in the electrolyte in step 3), which cannot effectively suppress impurities such as Ni, As, Sb, and Bi in the product, ultimately resulting in poor purity of the cathode copper product. In addition, the missing component in the composite additive used in step 3) of Comparative Example 8 prevents it from controlling the cathode crystal morphology, ultimately causing the cathode dendrites to grow wildly, accompanied by impurity spots and powder shedding, completely losing the physical properties of high-purity copper.

[0081] Finally, it should be noted that the above are only some preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A copper electrowinning refining complex additive, characterized by: The cathode crystallization fine control agent includes hydroxyethyl cellulose and sodium polydithiobisphane sulfonate, the key impurity selective inhibitor is a modified chitosan derivative, and the electrolyte reinforcing agent includes chloride ions and rare earth chlorides.

2. The copper electrowinning refining complex additive according to claim 1, characterized by: In the cathode crystallization fine control agent, the mass ratio of hydroxyethyl cellulose to sodium polydithiobisphane sulfonate is (5:1) to (10:1).

3. The copper electrowinning refining composite additive according to claim 1, characterized in that: The modified chitosan derivative is at least one of carboxymethyl chitosan and hydroxypropyl trimethyl ammonium chloride chitosan.

4. The copper electrowinning refining composite additive according to claim 1, characterized in that: In the electrolyte reinforcing agent, the chloride ions are provided by hydrochloric acid or sodium chloride, and the rare earth chlorides are at least one of cerium chloride and lanthanum chloride.

5. The copper electrowinning refining composite additive according to claim 1, characterized in that: When the copper electrolytic refining composite additive is used for copper electrolytic refining, the working concentration in the electrolyte is: hydroxyethyl cellulose 10-50 mg / L, sodium polydithiobisphane sulfonate 1-10 mg / L, key impurity selective inhibitor 5-30 mg / L, chloride ions 30-60 mg / L, and rare earth chlorides 2-15 mg / L.

6. A short process for efficient production of 5N grade high purity copper from scrap copper, characterized by, The method comprises the following steps: 1) Pretreatment and casting of waste copper: clean the waste copper raw material, and require that the total concentration of impurities such as nickel, arsenic, antimony, and bismuth in the waste copper raw material be ≤1.6 wt%, then melt the waste copper raw material into copper water in a protective atmosphere, then sequentially refine and filter the molten copper water, and finally cast the copper water into anode plates; 2) Short-time surface oxidation and rapid cooling of the anode plates: perform short-time surface oxidation treatment on the anode plates obtained in step 1) in an oxygen-containing atmosphere at a temperature of 650-800°C for 5-30 minutes, and then perform rapid cooling to form a functional oxidation layer on the surface of the anode plates; 3) Electrolytic refining: add the copper electrolytic refining composite additive described in claim 1 to the electrolyte, and perform electrolytic refining in an electrolytic cell with the anode plates treated in step 2) as anodes to obtain the desired 5N high-purity copper.

7. The short process for the production of 5N high purity copper from scrap copper according to claim 6, characterized in that: In step 1), the concentration of each single-element impurity in the waste copper raw material is limited to: nickel ≤1.4 wt%, arsenic ≤0.12 wt%, antimony ≤0.15 wt%, and bismuth ≤0.08 wt%.

8. The short-process technology for efficiently preparing 5N-grade high-purity copper from scrap copper according to claim 6, characterized in that: In step 1), the refining refers to injecting a composite refining agent carried by an inert gas into the molten copper water, and the composite refining agent is composed of an alkaline flux and an oxidizing agent in a mass ratio of 1: (0.1-0.5); the alkaline flux is an alkali metal carbonate; and the oxidizing agent is an alkali metal nitrate.

9. The short process for the production of 5N high purity copper from scrap copper according to claim 8, characterized in that: The adding amount of the composite refining agent is 1-1.5% of the mass of the copper water; the melt filtration refers to continuously passing the copper water through a foam ceramic filter with a porosity of 20-60 PPI; the rapid cooling refers to stably reducing the surface temperature of the anode plate from 650-800℃ after the oxidation treatment to 200-400℃ within 10 minutes at a cooling rate of 50-65℃ / min; during the electrolytic refining process, the electrolyte used is a copper sulfate-sulfuric acid system, wherein the copper ion concentration is 40-50 g / L, the sulfuric acid concentration is 180-220 g / L, the electrolysis temperature is 55-65℃, and the current density is 200-280 A / m 2 .

10. The high purity copper prepared by the short process for preparing 5N high purity copper from scrap copper according to any one of claims 6-9, characterized in that: The purity of the copper is not less than 99.999%, and the content of each single impurity element of arsenic, antimony, bismuth, and nickel is less than 0.1 ppm.

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