A production process for preparing high-conductivity red copper ingot by red copper scrap smelting

Abstract

The present application relates to copper smelting technical field, especially a kind of production process for preparing high-conductive red copper ingot by red copper scrap smelting, comprising the following steps: placing red copper scrap in open-hole hopper to drain moisture;After being beaten into briquettes, it is sent into smelting furnace;After being melted into copper liquid, copper-phosphorus alloy is added in proportion for deoxidization;Refining agent is added, stirred and kept warm;After confirming that iron content meets the standard by sampling detection, it is transferred into holding furnace;Copper liquid surface is covered with charcoal, and inert gas is introduced;Copper-phosphorus alloy is added, and high-conductive red copper ingot is casted.The ratio of refining agent is matched with the removal characteristics of harmful impurities such as iron in copper liquid, can fully react with copper liquid, and generate impurity slag which is easy to separate from copper liquid.And in the refining process, stirring time, holding time and other parameters are reasonably controlled.Furthermore, by adding copper-phosphorus alloy to adjust the phosphorus content of copper liquid, it is ensured that the purity of each batch of copper liquid meets the preparation requirements of high-conductive red copper ingot.

Description

Technical Field

[0001] This invention relates to the field of copper smelting technology, and in particular to a production process for preparing highly conductive copper ingots by smelting copper scraps. Background Technology

[0002] As the core raw material for deep processing of copper, the conductivity of copper ingots directly determines the performance of the end products. Typically, its conductivity is required to be no less than 98% IACS, and the content of impurities such as iron and oxygen must be strictly controlled at extremely low levels.

[0003] In industrial production, copper scraps, as byproducts generated during copper processing, are widely available and inexpensive. Recycling and smelting them to produce copper ingots is an important way to achieve resource recycling and reduce production costs. However, current processes for smelting copper scraps to produce high-conductivity copper ingots generally suffer from difficulties in controlling the purity of the molten copper. Specifically, the surface of copper scraps easily absorbs moisture, oil, and small amounts of impurities. During smelting, the gases produced by the thermal decomposition of moisture can cause pores in the molten copper, while the combustion of oil and residual impurities introduce additional impurities. Furthermore, during smelting, molten copper easily reacts with oxygen in the air to generate oxide impurities, and existing deoxidation and refining processes cannot adequately remove harmful impurities such as iron and oxygen from the molten copper. Ultimately, this results in insufficient purity in the prepared copper ingots, making it difficult to meet the requirements for high conductivity.

[0004] Therefore, it is urgent for technical personnel to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a production process for preparing highly conductive copper ingots by smelting copper scraps, aiming to solve the problems of difficulty in controlling the purity of molten copper in existing copper scrap smelting processes, due to impurities adsorbed by copper scraps, oxidation of molten copper, and insufficient deoxidation and refining.

[0006] This invention relates to a production process for preparing highly conductive copper ingots by smelting copper scrap, comprising the following steps: S1. Place the copper shavings in the perforated hopper and drain off the water. S2. After the copper scraps are broken into lumps, they are put into the smelting furnace and the surface is completely covered with charcoal. S3. After completely melting into molten copper, add a copper-phosphorus alloy containing 10-14% phosphorus at a ratio of 0.3-1 kg / ton for deoxidation; S4. Add refining agent at a rate of 1.0-2.0 kg / ton of molten copper, stir for 5 minutes, and keep warm for 20-30 minutes; then remove some of the charcoal to expose 30-50% of the molten copper, and continue to keep warm for 40-60 minutes. The refining agent, by mass percentage, consists of 15-25% sodium hexafluoroaluminate, 8-12% sodium carbonate, 15-25% anhydrous borax, 8-18% calcium fluoride, 8-18% sodium fluorosilicate, and the balance kaolin. S5. Remove the remaining charcoal and slag to completely expose the molten copper, then quickly cover it with charcoal and take a sample for testing; after confirming that the iron content is ≤10ppm, transfer the molten copper to the holding furnace. S6. The surface of the molten copper inside the furnace is covered with charcoal, and inert gas is continuously introduced into the bottom of the furnace. S7. By adding copper-phosphorus alloy containing 10-14% phosphorus, the phosphorus content of the copper liquid is adjusted to ≤20ppm, and a high-conductivity copper ingot is obtained by casting.

[0007] As a further improvement to the technical solution disclosed in this invention, in S4, the refining agent is prepared by mixing sodium hexafluoroaluminate, anhydrous borax, calcium fluoride, sodium fluorosilicate, and kaolin in a certain proportion, and ball milling at 30-50°C for 30-45 minutes to obtain a composite powder; sodium carbonate is added to the composite powder and mixed for 10-15 minutes, and then vacuum sealed for later use.

[0008] As a further improvement to the technical solution disclosed in this invention, in S4, after removing some of the charcoal, a gradient temperature control method is adopted to reduce the temperature of the copper liquid to 1100-1120°C at a rate of 5-8°C per minute; and during the gradient temperature control process, 0.1-0.3 kg / ton of lanthanum-cerium rare earth copper intermediate alloy is added simultaneously and stirred.

[0009] As a further improvement to the technical solution disclosed in this invention, in S5, the copper liquid is transferred from the smelting furnace to the holding furnace by a sealed chute for closed transport, and the temperature fluctuation of the copper liquid is controlled within ±10℃.

[0010] As a further improvement to the technical solution disclosed in this invention, in S6, the inert gas is argon, and the pressure is controlled to be 0.02-0.08 MPa.

[0011] As a further improvement to the technical solution disclosed in this invention, in S7, the casting adopts a vertical continuous casting method, and the casting speed is controlled at 150-250 mm / min, and the crystallizer adopts a tapered design with a taper of 0.5-1.0°.

[0012] In practical applications, the production process for preparing highly conductive copper ingots by smelting copper scraps disclosed in this invention can achieve at least the following beneficial technical effects, specifically: 1) The refining agent used in S4 is formulated to match the removal characteristics of harmful impurities such as iron in molten copper. It can fully react chemically with molten copper to generate impurity slag that is easily separated from the molten copper, thus improving the thoroughness of impurity removal from the source. Furthermore, during the smelting and refining process, the stirring time, holding time, and exposed area of ​​molten copper are reasonably controlled to ensure that the refining reaction proceeds fully. 2) After S4 completes the impurity removal, it is combined with S5 sampling and testing and S6 anti-secondary oxidation operation to provide a good foundation for the subsequent copper liquid composition control. In addition, copper-phosphorus alloy is added in S7 to adjust the phosphorus content of copper liquid, promote the stability of copper liquid composition, and ensure that the purity of each batch of copper liquid meets the preparation requirements of high conductivity copper ingot. Detailed Implementation

[0013] The technical solution disclosed in this invention will be further described in detail below with reference to specific embodiments. By implementing a copper scrap smelting and desulfurization process in conjunction with a composite refining agent, deep impurity removal from molten copper, stable iron content control below 10 ppm, and high-conductivity copper ingot quality standards are achieved. Specific embodiments are as follows: Refining agent The refining agent used in this invention, by mass percentage, consists of 15-25% sodium hexafluoroaluminate, 8-12% sodium carbonate, 15-25% anhydrous borax, 8-18% calcium fluoride, 8-18% sodium fluorosilicate, and the balance kaolin.

[0014] The detailed preparation method of the refining agent includes the following steps: 1) Weigh out sodium hexafluoroaluminate, anhydrous borax, calcium fluoride, sodium fluorosilicate and kaolin according to the ratio, and ball mill them at 30-50℃ for 30-45 min to obtain composite powder; 2) Add sodium carbonate to the composite powder, mix for 10-15 minutes, and then vacuum seal for later use.

[0015] Production process for preparing high-conductivity copper ingots by smelting copper scrap Example 1 S1. Place the copper shavings in the perforated hopper and drain off the water. S2. After the copper scraps are broken into lumps, they are put into the smelting furnace and the surface is completely covered with charcoal with a thickness of 50-80mm. S3. After completely melting into molten copper, add copper-phosphorus alloy containing 12% phosphorus at a ratio of 0.5 kg / ton for deoxidation; S4. Add refining agent at a ratio of 1.0 kg / ton of molten copper, with the following proportions: sodium hexafluoroaluminate 20%, sodium carbonate 10%, anhydrous borax 20%, calcium fluoride 13%, sodium fluorosilicate 13%, and the remainder being kaolin; stir for 5 minutes and keep warm for 25 minutes; then remove some of the charcoal to expose 40% of the molten copper, and use gradient temperature control to reduce the temperature to 1110℃ at a rate of 6℃ / min, while simultaneously adding 0.2 kg / ton of molten copper of lanthanum-cerium rare earth copper master alloy (RE content 10%) and stirring. S5. Remove the remaining charcoal and slag to completely expose the molten copper, then quickly cover it with charcoal and take samples for testing; after confirming that the iron content meets the standard, transfer the molten copper into the holding furnace through a sealed chute, and control the temperature fluctuation within ±10℃. S6. The surface of the copper liquid inside the heat preservation furnace is covered with charcoal, and argon gas is continuously introduced into the bottom of the furnace at a pressure of 0.05MPa. S7. Add copper-phosphorus alloy containing 12% phosphorus to adjust the phosphorus content of copper liquid to 15ppm. Use vertical continuous casting with a casting speed of 200mm / min and a crystallizer taper of 0.8° to cast high-conductivity copper ingots.

[0016] Example 2 S1. Place the copper shavings in the perforated hopper and drain off the water. S2. After the copper scraps are broken into lumps, they are put into the smelting furnace and the surface is completely covered with 50-80mm of charcoal. S3. After completely melting into copper liquid, add copper-phosphorus alloy containing 12% phosphorus at a ratio of 1kg / ton for deoxidation; S4. Add refining agent at a ratio of 1.0 kg / ton of molten copper, with the following proportions: sodium hexafluoroaluminate 15%, sodium carbonate 12%, anhydrous borax 25%, calcium fluoride 18%, sodium fluorosilicate 18%, and the remainder being kaolin; stir for 5 minutes and keep warm for 25 minutes; then remove some of the charcoal to expose 40% of the molten copper, and use gradient temperature control to reduce the temperature to 1110℃ at a rate of 6℃ / min, while simultaneously adding 0.2 kg / ton of molten copper of lanthanum-cerium rare earth copper master alloy (RE content 10%) and stirring. S5. Remove the remaining charcoal and slag to completely expose the molten copper, then quickly cover it with charcoal and take samples for testing; after confirming that the iron content meets the standard, transfer the molten copper into the holding furnace through a sealed chute, and control the temperature fluctuation within ±10℃. S6. The surface of the molten copper in the heat preservation furnace is covered with charcoal, and argon gas is continuously introduced into the bottom of the furnace at a pressure of 0.05 MPa. S7. Add copper-phosphorus alloy containing 12% phosphorus to adjust the phosphorus content of copper liquid to 15ppm. Use vertical continuous casting with a casting speed of 200mm / min and a crystallizer taper of 0.8° to cast high-conductivity copper ingots.

[0017] Example 3 S1. Place the copper shavings in the perforated hopper and drain off the water. S2. After the copper scraps are broken into lumps, they are put into the smelting furnace and the surface is completely covered with 50-80mm of charcoal. S3. After completely melting into molten copper, add copper-phosphorus alloy containing 12% phosphorus at a ratio of 0.8 kg / ton for deoxidation; S4. Add refining agent at a ratio of 1.0 kg / ton of molten copper, with the following proportions: sodium hexafluoroaluminate 25%, sodium carbonate 8%, anhydrous borax 15%, calcium fluoride 8%, sodium fluorosilicate 8%, and the remainder being kaolin; stir for 5 minutes and keep warm for 25 minutes; then remove some of the charcoal to expose 40% of the molten copper, and use gradient temperature control to reduce the temperature to 1110℃ at a rate of 6℃ / min, while simultaneously adding 0.2 kg / ton of molten copper of lanthanum-cerium rare earth copper master alloy (RE content 10%) and stirring. S5. Remove the remaining charcoal and slag to completely expose the molten copper, then quickly cover it with charcoal and take samples for testing; after confirming that the iron content meets the standard, transfer the molten copper into the holding furnace through a sealed chute, and control the temperature fluctuation within ±10℃. S6. The surface of the molten copper in the heat preservation furnace is covered with charcoal, and argon gas is continuously introduced into the bottom of the furnace at a pressure of 0.05 MPa. S7. Add copper-phosphorus alloy containing 12% phosphorus to adjust the phosphorus content of copper liquid to 15ppm. Use vertical continuous casting with a casting speed of 200mm / min and a crystallizer taper of 0.8° to cast high-conductivity copper ingots.

[0018] Comparative Example S1. Place the copper scraps in the perforated hopper to drain the water; S2. Copper scraps are packed into the smelting furnace and completely covered with charcoal. S3. After complete melting, add 12% phosphorus copper-phosphorus alloy at 4 kg / ton for deoxidation; S4. Add conventional borax-sodium carbonate refining agent (mass percentage: anhydrous borax 60%, sodium carbonate 40%), stir for 5 minutes, and keep warm for 25 minutes; remove some of the charcoal to expose 40% of the surface area, and keep warm for 50 minutes. S5. Remove slag and cover with charcoal, then convert to a converter; S6. The surface of the molten copper inside the holding furnace is covered with charcoal. S7, Vertical continuous casting.

[0019] The performance of the copper ingots obtained in Examples 1-3 and the comparative example was tested, and the test results are shown in the table below: Test results show that the copper scrap smelting process and composite refining agent used in Examples 1-3 of this invention for preparing high-conductivity copper ingots have significantly better impurity removal and deoxidation effects than traditional industrial refining processes. It can stably control the iron content below 10 ppm and the oxygen content below 25 ppm, with a stable conductivity ≥98% IACS, meeting the stringent standards for high-end, high-conductivity copper ingots. Furthermore, the ingots are free of porosity and inclusions, and have a dense microstructure. Simultaneously, this process forms a complete closed-loop process through gradient temperature control, rare earth modification, inert gas purification, and precise phosphorus control, effectively suppressing secondary oxidation and impurity re-dissolution, maximizing the protection of copper liquid purity, and ensuring a 100% compliance rate for each batch of products.

[0020] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A production process for preparing highly conductive copper ingots by smelting copper scrap, characterized in that, Includes the following steps: S1. Place the copper shavings in the perforated hopper and drain off the water. S2. After the copper scraps are broken into lumps, they are put into the smelting furnace and the surface is completely covered with charcoal. S3. After completely melting into molten copper, add a copper-phosphorus alloy containing 10-14% phosphorus at a ratio of 0.3-1 kg / ton for deoxidation; S4. Add refining agent at a rate of 1.0-2.0 kg / ton of molten copper, stir for 5 minutes, and keep warm for 20-30 minutes; then remove some of the charcoal to expose 30-50% of the molten copper, and continue to keep warm for 40-60 minutes. The refining agent, by mass percentage, consists of 15-25% sodium hexafluoroaluminate, 8-12% sodium carbonate, 15-25% anhydrous borax, 8-18% calcium fluoride, 8-18% sodium fluorosilicate, and the balance kaolin. S5. Remove the remaining charcoal and slag to completely expose the molten copper, then quickly cover it with charcoal and take a sample for testing; after confirming that the iron content is ≤10ppm, transfer the molten copper to the holding furnace. S6. The surface of the molten copper inside the furnace is covered with charcoal, and inert gas is continuously introduced into the bottom of the furnace. S7. By adding copper-phosphorus alloy containing 10-14% phosphorus, the phosphorus content of the copper liquid is adjusted to ≤20ppm, and a high-conductivity copper ingot is obtained by casting.

2. The production process for preparing highly conductive copper ingots by smelting copper scraps according to claim 1, characterized in that, In S4, the refining agent is prepared by mixing sodium hexafluoroaluminate, anhydrous borax, calcium fluoride, sodium fluorosilicate, and kaolin in a certain proportion, and ball milling at 30-50°C for 30-45 minutes to obtain a composite powder; adding sodium carbonate to the composite powder and mixing for 10-15 minutes, and then vacuum sealing for later use.

3. The production process for preparing highly conductive copper ingots by smelting copper scraps according to claim 1, characterized in that, In S4, after removing some of the charcoal, a gradient temperature control method is used to reduce the temperature of the copper liquid to 1100-1120℃ at a rate of 5-8℃ per minute; and during the gradient temperature control process, 0.1-0.3 kg / ton of lanthanum-cerium rare earth copper intermediate alloy is added simultaneously and stirred.

4. The production process for preparing highly conductive copper ingots by smelting copper scraps according to claim 1, characterized in that, In S5, the copper liquid is transferred from the smelting furnace to the holding furnace using a sealed chute for closed-loop transportation, and the temperature fluctuation of the copper liquid is controlled within ±10℃.

5. The production process for preparing highly conductive copper ingots by smelting copper scraps according to claim 1, characterized in that, In S6, the inert gas is argon, and the pressure is controlled to be 0.02-0.08 MPa.

6. The production process for preparing highly conductive copper ingots by smelting copper scraps according to claim 1, characterized in that, In S7, the casting adopts a vertical continuous casting method, and the casting speed is controlled at 150-250 mm / min. The crystallizer adopts a tapered design with a taper of 0.5-1.0°.

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