Application of metal lead in improving drawing property of regenerated low-oxygen copper wire rod

Abstract

This invention discloses the application of metallic lead in improving the wire drawing properties of recycled low-oxygen copper wire. The composition of the recycled low-oxygen copper wire, by weight percentage, is: lead 0.05-0.052%; nickel 0.0058-0.0062%; copper 99.93-99.95%; the balance being unavoidable impurities totaling no more than 0.005%; among the unavoidable impurities, tin content is less than 0.0046%, iron content is less than 0.001%, and zinc content is... The content is less than 0.001%. The processing of recycled low-oxygen copper wire includes the following steps: S1, wrapping lead blocks with copper sheets to form lead balls; S2, adding the lead balls in batches to the recycled copper liquid in the electric melting furnace; S3, taking multi-point samples of the recycled copper liquid and testing them; S4, stopping the addition of lead balls when the test results show that all components are qualified; S5, continuously casting the copper liquid in S4 into copper rods; S6, controlling the temperature of the copper rods in S5 at 60-100℃ and drawing them into copper wire. When the influence of other elements in scrap copper on copper wire cannot be avoided, the content of nickel and lead is mainly controlled. The two work together. Nickel can significantly improve strength, corrosion resistance, hardness, electrical resistance and thermoelectric properties, and reduce the temperature coefficient of resistivity. Lead can reduce the movement resistance of copper alloys, thereby improving the fluidity of the alloy and improving the casting effect. When adding lead to molten copper, it is wrapped in copper sheet for two reasons. First, it prevents the reactive lead from oxidizing too quickly before it enters the molten copper. This would cause lead oxide, which is heavier than copper, to sink to the bottom of the furnace, resulting in waste and hindering the drawing ability of the copper. Second, lead has a much lower melting point than copper. Wrapping lead in copper sheet prevents the lead from melting too quickly and concentrating in the upper part of the molten copper, causing uneven distribution and affecting product quality. This process also reduces stirring and prevents excessive oxygen from mixing into the molten copper, which could oxidize the metal.

Description

Technical Field

[0001] This invention relates to the field of copper wire manufacturing technology, and in particular to the application of metallic lead in improving the drawing properties of recycled low-oxygen copper wire. Background Technology

[0002] Generally, recycled copper is used to recast copper rods, which are then drawn into copper wires. During the processing, the impurities in the recycled copper often result in substandard quality of the copper wires, leading to unsatisfactory performance in torsion and drawing tests. In order to process recycled copper wires with high drawability from recycled copper containing various complex elements, which satisfies the concept of resource recycling, environmental protection, and energy conservation, while ensuring the quality of the copper wires, a low-oxygen, high-drawability recycled copper is urgently needed.

[0003] It is well known that lead has a significant impact on the casting performance and solidification process of copper alloys. A suitable lead content can reduce the resistance to movement in copper alloys, thereby improving their fluidity and casting performance, resulting in high wire drawing properties. Furthermore, lead also has a certain influence on the grain size of copper alloys, allowing control over grain size and distribution. However, how to add lead to molten copper during scrap copper smelting without oxidation, and ensure that the lead's melting rate is not inconsistent due to temperature variations, thus preventing uneven lead distribution, remains a challenge in the processing of high-drawability copper wires. Summary of the Invention

[0004] The purpose of this invention is to provide an application of metallic lead in improving the drawing properties of recycled low-oxygen copper wire, so as to solve the problems of impurities in old copper leading to substandard copper wire quality, and the difficulty in adding and mixing lead elements in copper liquid when improving copper wire.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] An application of metallic lead in improving the wire drawing properties of recycled low-oxygen copper wire, wherein the components of the recycled low-oxygen copper wire, by weight percentage, are:

[0007] Lead content: 0.05–0.052%;

[0008] Nickel content: 0.0058–0.0062%;

[0009] Copper content: 99.93%–99.95%;

[0010] The margin is that the total unavoidable impurities content is not greater than 0.005%;

[0011] The unavoidable impurities contain less than 0.0046% tin, less than 0.001% iron, and less than 0.001% zinc.

[0012] The processing of recycled low-oxygen copper wire includes the following steps:

[0013] S1. Wrap a lead block with copper sheet to form a lead ball;

[0014] S2. Add the lead balls into the recycled copper liquid in the electric melting furnace in batches;

[0015] S3. Take samples of the recycled copper solution at multiple points and test them.

[0016] S4. Stop the shot put when all test results are within acceptable limits.

[0017] S5. Cast the molten copper from S4 into a copper rod;

[0018] S6. Control the temperature of the copper rod in S5 at 60-100℃ and draw it into copper wire.

[0019] A further technical solution is that the copper sheet thickness of the lead ball is 0.1-0.5mm, 0.5-1mm, 1-2mm, 2-3mm, 3-5mm, or 5-10mm.

[0020] A further technical solution is that the particle size distribution of the shot put is 1:1:2:3:2:1.

[0021] A further technical solution is: in step S4, quartz sand is added to the copper liquid and stirred to remove slag.

[0022] A further technical solution is: in step S5, the surface of the copper liquid is sealed with a reducing floating substance.

[0023] A further technical solution is that the reducing flocculation material is wood or charcoal.

[0024] A further technical solution is that the breakage limit of the copper wire is less than 0.1 mm.

[0025] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0026] This invention proposes the application of metallic lead in improving the drawing properties of recycled low-oxygen copper wire. When the influence of other elements in waste copper on copper wire cannot be avoided, the main focus is on controlling the content of nickel and lead. The two work together, with nickel significantly improving strength, corrosion resistance, hardness, electrical resistance, and thermoelectric properties, and reducing the temperature coefficient of resistivity. Lead can reduce the movement resistance of copper alloys, thereby improving the fluidity of the alloy and enhancing the casting effect.

[0027] When adding lead to molten copper, it is wrapped in copper sheet for two reasons. First, it prevents the reactive lead from oxidizing too quickly before it enters the molten copper. This would cause lead oxide, which is heavier than copper, to sink to the bottom of the furnace, resulting in waste and hindering the drawing ability of the copper. Second, lead has a much lower melting point than copper. Wrapping lead in copper sheet prevents the lead from melting too quickly and concentrating in the upper part of the molten copper, causing uneven distribution and affecting product quality. This process also reduces stirring and prevents excessive oxygen from mixing into the molten copper, which could oxidize the metal. Attached Figure Description

[0028] Figure 1 This is a metallographic photograph (cross section) of the recycled low-oxygen copper wire with a lead content of 0.052% according to the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0030] Therefore, the following detailed description of embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0032] Example 1:

[0033] An application of metallic lead in improving the wire drawing properties of recycled low-oxygen copper wire, wherein the components of the recycled low-oxygen copper wire, by weight percentage, are:

[0034] Lead content: 0.05–0.052%;

[0035] Nickel 0.0058–0.0062%

[0036] Copper 99.93%–99.95%

[0037] The margin is that the total unavoidable impurities content is not greater than 0.005%;

[0038] The unavoidable impurities contain less than 0.0046% tin, less than 0.001% iron, and less than 0.001% zinc.

[0039] The processing of recycled low-oxygen copper wire includes the following steps:

[0040] S1. Wrap a lead block with copper sheet to form a lead ball;

[0041] S2. Add the lead balls into the recycled copper liquid in the electric melting furnace in batches;

[0042] S3. Take samples of the recycled copper solution at multiple points and test them.

[0043] S4. Stop the shot put when all test results are within acceptable limits.

[0044] S5. Cast the molten copper from S4 into a copper rod;

[0045] S6. Control the temperature of the copper rod in S5 at 60-100℃ and draw it into copper wire.

[0046] In scrap copper, various metallic elements are mixed. Especially after remelting, the originally complex copper material becomes a molten copper with various elements alternating or even combined. This molten copper needs to be purified and refined before it can be used. The content of each element in the molten copper is specifically controlled according to the intended use and performance of the subsequent product. Therefore, in order to ensure that the copper wire does not lose strength and conductivity, it is of paramount importance to improve its processing performance, especially its wire drawing ability. The mechanical properties of the copper wire made from the above low-oxygen, high-wire-drawing recycled copper with a lead content of 0.05-0.052% are tested as follows:

[0047]

[0048]

[0049] The above torsion test results were obtained by conducting three tests on copper wires with different lead contents but the same length and diameter using a torsion testing machine; the wire drawing test was conducted three times using wire drawing plates with diameters decreasing from large to small on copper wires with different lead contents but the same length and diameter, and the diameter at which the wire broke was the final result.

[0050] It is clear from the above experimental results that copper wire exhibits the best drawability when the lead content is 0.052%. Generally, in copper processing, to ensure the strength of the copper material, the lead content is controlled to be less than 0.05%. Therefore, to maintain drawability, the nickel content needs to be controlled between 0.0058% and 0.0062% to improve strength, corrosion resistance, hardness, electrical resistance, and thermoelectric properties, while reducing the temperature coefficient of resistivity. Thus, cupronickel possesses exceptionally good mechanical and physical properties compared to other copper alloys, exhibiting good ductility, high hardness, beautiful color, corrosion resistance, and deep-drawing performance.

[0051] When adding lead to molten copper, it is wrapped in copper sheet for two reasons. First, it prevents the reactive lead from oxidizing too quickly before it enters the molten copper. This would cause lead oxide, which is heavier than copper, to sink to the bottom of the furnace, resulting in waste and hindering the drawing ability of the copper. Second, lead has a much lower melting point than copper. Wrapping lead in copper sheet prevents the lead from melting too quickly and concentrating in the upper part of the molten copper, causing uneven distribution and affecting product quality. This process also reduces stirring and prevents excessive oxygen from mixing into the molten copper, which could oxidize the metal.

[0052] Figure 1 When the lead content is low, it is distributed in a network at the grain boundaries, and its color is black or it forms a dark eutectic. This uniform grain distribution will greatly improve the copper wire drawing properties.

[0053] Preferably, the copper sheet thickness of the lead ball is 0.1-0.5 mm, 0.5-1 mm, 1-2 mm, 2-3 mm, 3-5 mm, or 5-10 mm.

[0054] The copper sheet thickness is inconsistent so that each type of copper sheet melts at a different rate in the molten copper, ensuring that the lead blocks are released from the copper sheet at different times. This allows the lead blocks to be distributed at different liquid levels in the molten copper, improving the uniformity of the lead block distribution.

[0055] Preferably, the shot put's particle size distribution is 1:1:2:3:2:1.

[0056] Smelting furnaces, such as electric furnaces, may have uneven copper molten temperature due to equipment limitations. Therefore, the above-mentioned gradation can ensure that the lead blocks are most abundant in the high-temperature zone and are evenly distributed through convection.

[0057] Preferably, in step S4, quartz sand is added to the molten copper and the mixture is stirred and slag is removed.

[0058] When lead blocks are encased in copper or immersed in molten copper, oxidation is inevitable, leading to the production of lead oxide. Although lead is easily removed by slag formation, its specific gravity is much greater than that of copper. Generally, after melting, lead oxide tends to sink to the bottom of the furnace, making it difficult to stir up during oxidation. Therefore, when removing lead, it is necessary to remove the lead oxide (specific gravity 9.2) that has settled at the bottom of the furnace. We once sampled the copper that was not completely drained from the furnace during a shutdown and found that the lead content was several to tens of times higher than the standard. To address this, we appropriately sprinkled some quartz sand into the furnace bottom before each charging, so that the lead oxide that had settled at the bottom could melt and combine with SiO to form PbSiO3, which would then float to the surface of the molten copper and be removed.

[0059] Preferably, in step S5, the surface of the molten copper is sealed with a reducing agent. The reducing agent is wood or charcoal.

[0060] When tapping copper, a layer of reducing floating material is placed on top of the molten copper to prevent the copper from absorbing oxygen.

[0061] Preferably, the breakage limit of the copper wire is less than 0.1 mm.

[0062] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An application of metallic lead in improving the drawing properties of recycled low-oxygen copper wire, characterized in that, The components of the recycled low-oxygen copper wire, by weight percentage, are as follows: Lead content: 0.05–0.052%; Nickel content: 0.0058–0.0062%; Copper content: 99.93%–99.95%; The margin is that the total unavoidable impurities content is not greater than 0.005%; The unavoidable impurities contain less than 0.0046% tin, less than 0.001% iron, and less than 0.001% zinc. The processing of recycled low-oxygen copper wire includes the following steps: S1. Wrap a lead block with copper sheet to form a lead ball; S2. Add the lead balls into the recycled copper liquid in the electric melting furnace in batches; S3. Take samples of the recycled copper solution at multiple points and test them. S4. Stop the shot put when all test results are within acceptable limits. S5. Cast the molten copper from S4 into a copper rod; S6. Control the temperature of the copper rod in S5 at 60-100℃ and draw it into copper wire.

2. The application of metallic lead according to claim 1 in improving the drawing properties of recycled low-oxygen copper wire, characterized in that: The copper sheet thicknesses of the lead balls are 0.1–0.5 mm, 0.5–1 mm, 1–2 mm, 2–3 mm, 3–5 mm, and 5–10 mm, respectively.

3. The application of metallic lead according to claim 2 in improving the drawing properties of recycled low-oxygen copper wire, characterized in that: The particle size distribution of the shot put is 1:1:2:3:2:

1.

4. The application of metallic lead according to claim 1 in improving the drawing properties of recycled low-oxygen copper wire, characterized in that: In step S4, quartz sand is added to the molten copper and the mixture is stirred and slag is removed.

5. The application of metallic lead according to claim 1 in improving the drawing properties of recycled low-oxygen copper wire, characterized in that: In step S5, the surface of the copper liquid is sealed with a reducing float.

6. The application of metallic lead according to claim 5 in improving the wire drawing properties of recycled low-oxygen copper wire, characterized in that: The reducing floating material is wood or charcoal.

7. The application of metallic lead according to claim 1 in improving the wire drawing properties of recycled low-oxygen copper wire, characterized in that: The breakage limit of the copper wire is less than 0.1 mm.

Images