Method and device for preparing oxygen-free copper tubes from recycled copper, corrosion-resistant copper tubes and casting process

Abstract

The present invention discloses a method and device for preparing oxygen-free copper tubes from recycled copper, as well as a corrosion-resistant copper tube and a casting process, belonging to the field of copper treatment. The oxygen content of the corrosion-resistant copper tube is less than 5 ppm, the hydrogen content is less than 0.3 ppm, the phosphorus content is 0.1% - 0.3%, and the balance is copper. The method for preparing oxygen-free copper tubes from recycled copper includes S1: heating the copper liquid in the shaft furnace to a set temperature, adjusting the concentration of the reducing gas in the shaft furnace to increase the oxygen content of the copper liquid in the shaft furnace and make it greater than 30 ppm for primary impurity removal; S2: sequentially introducing the copper liquid in the shaft furnace into a chute, a refining furnace, a holding furnace, and a casting furnace. The temperature of the copper liquid in the chute, the refining furnace, the holding furnace, and the casting furnace gradually decreases. Inert gas + reducing gas is introduced into the chute, the refining furnace, the holding furnace, and the casting furnace, and the flow rate and pressure of the inert gas + reducing gas introduced into the chute, the refining furnace, the holding furnace, and the casting furnace gradually decrease for secondary impurity removal. The present invention is mainly used for preparing oxygen-free copper tubes from recycled copper and preparing corrosion-resistant copper tubes.

Description

Technical Field

[0001] The present invention relates to the field of copper processing, in particular to a method and device for preparing oxygen-free copper tubes from recycled copper, corrosion-resistant copper tubes, and a casting process. Background Art

[0002] Copper tubes are widely used in the fields of marine equipment, aerospace, nuclear power, high-end equipment, and refrigeration. To reduce dependence on natural resources, relieve environmental pressure, and provide a sustainable source of materials, copper in scrapped wire and cable, automotive radiators and refrigerators, copper-containing castings, waste bearings, used motors, used transformers, etc. can be recycled and reused to produce oxygen-free copper tubes. However, recycled copper contains oxygen, hydrogen, and other elements such as arsenic, antimony, bismuth, iron, lead, tin, nickel, zinc, and sulfur compared to traditional copper from copper ore. Oxygen, hydrogen, and other elements are impurities in oxygen-free copper tubes, and additional purification steps are required to remove the impurities to meet the same quality standards as those produced from traditional copper. For this reason, prior art such as the invention patent CN103725897A discloses a method for directly producing high-purity oxygen-free copper by continuous fire refining of scrap copper. After removing impurities by oxidation-reduction, borides and rare earths are added to remove hydrogen and deoxidize, but this method will introduce other impurities such as borides and rare earths, and the residues of borides and rare earths affect the composition of oxygen-free copper tubes. Therefore, currently, reducing gases are mostly used to reduce oxygen elements during the production of copper raw materials to produce oxygen-free copper tubes. For example, the utility model patent CN216780264U discloses a vertical furnace-horizontal continuous casting copper billet device, which produces tube billets through equipment such as a vertical furnace, a refining furnace, a mixing furnace, a standing furnace, and a seven-strand continuous casting furnace. A blowing brick is provided on the bottom wall of the cavity of the furnace body of the refining furnace, and reducing gas is blown in through a blowing device. By increasing the amount of reducing gas, the oxygen element content in the recycled copper tube is removed, and phosphor copper is added to remove impurities such as oxygen elements. However, only gas is introduced into the refining furnace in the above device, and the oxygen element content cannot be accurately controlled, which affects the quality of the recycled copper tube.

[0003] At the same time, in order to improve the heat exchange efficiency of copper tubes and reduce energy consumption, copper tubes for heat exchangers in aerospace and other fields are developing towards thin walls and small diameters. The thin walls make the copper tubes more likely to be corroded and perforated. For this reason, prior art such as the invention patent CN105143478A discloses a corrosion-resistant copper tube containing P at a ratio of 0.05-1.0% by weight, and the remaining part is composed of Cu and inevitable impurities. On the one hand, the high phosphorus content makes the copper tube brittle and hard, which may cause problems such as cracks during bending or forming. On the other hand, if the hydrogen and oxygen elements in the copper tube are not eliminated, the content of hydrogen and oxygen elements is relatively high, resulting in more cuprous oxide in the copper tube, a relatively high potential difference between grain boundaries and within grains, and poor ant nest corrosion resistance of the copper tube, and the copper tube is easily corroded. Summary of the Invention

[0004] The objective to be achieved by the present invention is to provide a corrosion-resistant copper tube, overcoming the deficiencies of the prior art and enhancing the corrosion resistance of the corrosion-resistant copper tube.

[0005] To achieve the above objective, the present invention adopts the following technical solution: a corrosion-resistant copper tube, wherein the oxygen element content of the corrosion-resistant copper tube is less than 5 ppm, the hydrogen element content is less than 0.3 ppm, and the phosphorus element content is 0.1% - 0.3%; the balance is copper element.

[0006] By adopting the above technical solution, by controlling the contents of oxygen element, hydrogen element, and phosphorus element in the corrosion-resistant copper tube, with the strict control that the oxygen element content is less than 5 ppm and the hydrogen element content is less than 0.3 ppm, cuprous oxide can be effectively eliminated, and the potential difference between grain boundaries and within grains can be reduced, thereby significantly reducing the oxides and hydrogen embrittlement phenomena that may cause corrosion in the corrosion-resistant copper tube. Additionally, with the precise control of the phosphorus element content, the phosphorus element can significantly enhance the corrosion resistance of the corrosion-resistant copper tube. Especially when used in humid, acidic or alkaline environments or seawater, an appropriate phosphorus content can also ensure the strength and hardness of the corrosion-resistant copper tube. The phosphorus element can also react with the oxygen element in the copper liquid to form phosphorus oxides, and the phosphorus oxides are volatile and will escape at high temperatures, thereby reducing the oxygen element content in the copper alloy. In addition to deoxidation, phosphorus can also react with other elements in the impurities to form compounds that are easy to separate from the copper liquid, thereby further achieving the purpose of purifying copper. Secondly, the balance is copper element, reducing the types of elements, ensuring a high copper element content, guaranteeing good electrical conductivity and thermal conductivity of the material, and at the same time retaining the good workability of copper itself, suitable for various forming, drawing, welding and other processing processes, and facilitating the manufacture of pipe fittings with complex shapes.

[0007] Furthermore, the tensile strength of the corrosion-resistant copper tube is not less than 250 MPa, the yield strength is 60 - 80 MPa, the elongation is not less than 45%, the solid residue is not more than 0.1 mg / m, and the residual oil on the inner wall is not more than 0.15 mg / m.

[0008] Adopting the above technical solution, the tensile strength is not less than 250 MPa, indicating that the corrosion-resistant copper tube has good ability to resist tensile failure and is suitable for application scenarios that bear large external forces. Secondly, the yield strength is 60 - 80 MPa, which helps to improve the forming performance of the corrosion-resistant copper tube. And, the elongation is not less than 45%, which means that the corrosion-resistant copper tube has good plastic deformation ability and can withstand large deformations without fracture. Then, the solid residue is not more than 0.1 mg / m, which means that there are very few solid impurities remaining inside the corrosion-resistant copper tube, helping to improve the purity and service life of the product. Next, the residual oil on the inner wall is not more than 0.15 mg / m, which shows that the inner surface of the corrosion-resistant copper tube is very clean, reducing the corrosion risk caused by oil stains. Thus, the corrosion-resistant copper tube not only has good mechanical properties, but also has excellent corrosion resistance and processing performance, and is suitable for a variety of harsh application environments.

[0009] Another object of the present invention is to provide a method for preparing oxygen-free copper tubes from recycled copper, comprising the following steps:

[0010] S1: Heating the copper liquid in the shaft furnace to a set temperature, adjusting the concentration of the reducing gas in the shaft furnace to increase the oxygen element content in the copper liquid in the shaft furnace to be greater than 30 ppm, and performing primary impurity removal;

[0011] S2: Sequentially introducing the copper liquid in the shaft furnace into a chute, a refining furnace, a holding furnace, and a casting furnace. The temperature of the copper liquid gradually decreases in the chute, the refining furnace, the holding furnace, and the casting furnace. Inert gas + reducing gas is introduced into the chute, the refining furnace, the holding furnace, and the casting furnace, and the flow rate and pressure of the inert gas + reducing gas introduced into the chute, the refining furnace, the holding furnace, and the casting furnace gradually decrease, performing secondary impurity removal to obtain oxygen-free copper tubes.

[0012] After adopting the above technical solution, the present invention has the following advantages: First, oxygen element has oxidizing property. The oxygen element can react with hydrogen element in the impurities through redox reaction to generate water. And the copper liquid in the shaft furnace is heated to the set temperature. The relatively high temperature of the copper liquid can provide sufficient activation energy to promote a relatively fast reaction rate. The generated water will also be heated and evaporated in the form of water vapor, so as to reduce the hydrogen element content in the copper liquid. At the same time, the oxygen element can also react with other elements in the impurities except hydrogen element through oxidation reaction to form oxides. Generally, the oxides are insoluble in the copper liquid but form a slag phase, which can be removed from the surface of the copper liquid by skimming the slag, so as to reduce the impurity content in the copper liquid. And the oxygen element itself is the impurity to be removed in the copper liquid. Without introducing other impurity removal agents, the types of impurities in the copper liquid will not increase. Thus, through reverse operation, first increase the oxygen element content in the copper liquid in the shaft furnace and increase the oxygen element content in the copper liquid to be greater than 30 ppm. There will be enough oxygen elements to carry out oxidation reaction with the impurities for primary impurity removal to ensure the impurity removal effect. If the oxygen element content in the copper liquid in the shaft furnace is lower than 30 ppm, the impurity removal effect will be poor, resulting in a relatively high impurity content in the copper liquid, increasing the difficulty of impurity removal in the subsequent treatment steps. If the impurity removal ability in the subsequent treatment steps is weak, it may lead to the impurity content in the finally produced oxygen-free copper tube still being higher than the target value, affecting the quality of the oxygen-free copper tube.

[0013] Secondly, since the reducing gas has reducibility, the reducing gas can react with the oxygen element in the impurities through a reduction reaction to generate an oxygen-containing gas, and the oxygen-containing gas is volatile, thereby reducing the oxygen element content in the copper liquid. At the same time, the reducing gas can also react with other elements in the impurities except the oxygen element through a reduction reaction to generate substances separable from the copper liquid, further reducing the impurity content. And since the temperature of the copper liquid is relatively high, the impurities will still react with the oxygen element through an oxidation-reduction reaction to form oxides and be removed from the copper liquid. Moreover, since a high-concentration reducing gas is likely to form an explosive mixture when mixed with air, inert gas + reducing gas is introduced into the chute, refining furnace, holding furnace, and casting furnace. Adding inert gas can reduce the flammable range of this mixture and reduce potential safety hazards. The addition of inert gas can also increase the total gas volume, thereby increasing the gas passing speed through the copper liquid, which helps to improve the reaction efficiency. Also, the impurities in the copper liquid are gradually reduced by the reducing gas when passing through the chute, refining furnace, holding furnace, and casting furnace in sequence. The copper liquid undergoes multiple steps of impurity removal to achieve refined control of the hydrogen and oxygen removal process, obtaining secondary impurity removal, which can better control the impurity content in the copper liquid. And the temperature of the copper liquid in the chute, refining furnace, holding furnace, and casting furnace gradually decreases. As the temperature of the copper liquid decreases, the solubility of the impurities will decrease, and they are more likely to precipitate from the copper liquid and react with the oxygen element to form a slag phase that is easy to separate, so that impurities can be removed more thoroughly and the purity of the oxygen-free copper tube can be improved. And the content of the impurities will decrease when entering the next furnace after being removed by the previous furnace. Correspondingly, the required amount of the reducing gas can also decrease, so that the flow rate and pressure of the inert gas + reducing gas introduced into the chute, refining furnace, holding furnace, and casting furnace gradually decrease. The gradually decreasing flow rate and pressure of the inert gas + reducing gas help to control the overflow of bubbles in the copper liquid, reduce the formation of pores, and can also ensure that the hydrogen and oxygen removal effect is always within the set range. At the same time, it also helps to control the stirring degree of the copper liquid, ensure the effective progress of oxidation slag formation, improve the quality of producing oxygen-free copper tubes from recycled copper, reduce energy consumption, and improve process efficiency.

[0014] Further, the concentration of the reducing gas in the shaft furnace, chute, refining furnace, holding furnace, and casting furnace gradually increases.

[0015] Adopting the above technical solution, as the concentration of the reducing gas gradually increases, the reduction reaction rate between the reducing gas and the impurities is faster, thereby more effectively removing the impurities. Gradually adjusting the concentration of the reducing gas makes the production process more flexible and can be adjusted according to different raw material or product requirements.

[0016] Further, the concentration of the reducing gas in the shaft furnace, chute, refining furnace, holding furnace, and casting furnace gradually increases from 2% to 5%.

[0017] With the above technical solution, by gradually increasing the concentration of the reducing gas, the removal process of impurities can be more precisely controlled, avoiding problems such as overoxidation or insufficient oxidation. If the concentration of the reducing gas is less than 2%, the relatively low concentration of the reducing gas may lead to a decrease in the reduction efficiency of impurities, prolong the production cycle, and may not effectively remove the impurities in the reduced copper, thus affecting the quality of the reduced copper. If the concentration of the reducing gas is greater than 5%, the high-concentration reducing gas may require more energy for heating and mixing, thereby increasing energy consumption. Using an excessive amount of reducing gas not only wastes resources but also increases the raw material cost.

[0018] Furthermore, the molten copper temperatures of the shaft furnace, chute, refining furnace, holding furnace, and casting furnace gradually decrease within the range of 1220 - 1150 °C.

[0019] With the above technical solution, at a relatively high temperature, the molten copper maintains good fluidity, which is conducive to rapid reactions and enables impurities to be effectively removed. If the temperature of the molten copper is higher than 1220 °C, the excessive temperature may promote the dissolution of impurities and affect the purity of the recycled copper. If the temperature of the molten copper is lower than 1150 °C, the too-low temperature may slow down the oxidation process of impurities, reduce the slag-making efficiency, and result in a relatively high impurity content in the recycled copper.

[0020] Furthermore, the reducing gas is CO.

[0021] With the above technical solution, CO is a powerful reducing agent that can react with the oxides in the molten copper and reduce them to metallic copper, improving the purity of the recycled copper. The CO reduction process is relatively mild and will not drastically change the properties of the molten copper, which is conducive to maintaining the stability of the molten copper and facilitating subsequent refining, casting, and other processing steps, improving the efficiency of the entire production chain and the product quality. Compared with other noble metal catalysts or complex chemical reagents, CO, as a common industrial gas, has a relatively low cost. Using CO as a reducing agent can effectively control the production cost. Finally, the presence of CO can also reduce the solubility of hydrogen in the molten copper, prompting hydrogen to precipitate in the form of bubbles, which helps to efficiently remove hydrogen, reduce the hydrogen embrittlement phenomenon of copper products, and improve their mechanical properties and service life.

[0022] Another object of the present invention is to provide a device for preparing oxygen-free copper tubes from recycled copper, including a shaft furnace, a chute, a refining furnace, a holding furnace, and a casting furnace. The chute, refining furnace, holding furnace, and casting furnace are all equipped with permeable bricks at the bottom for blowing in inert gas + reducing gas, implementing the method for preparing oxygen-free copper tubes from recycled copper according to any one of the above technical solutions.

[0023] With the above technical solution, the permeable brick design ensures uniform distribution of gas at the bottom of the furnace, increases the contact area between the gas and the molten copper and the reaction efficiency, and helps to effectively reduce the impurity content in the molten copper and improve the purity of the molten copper.

[0024] Another object of the present invention is to provide a casting process for corrosion-resistant copper pipes. Molten copper is obtained from the casting furnace of the method for preparing oxygen-free copper pipes from recycled copper according to any one of the above technical solutions. A phosphorus source is added to the molten copper, and the casting temperature of the molten copper is 1165°C ±5°C, the flow rate of the primary cooling water in the crystallizer is 45 - 55 L / min. A traction program is adopted. In the traction program, the starting pulling speed during casting is 100 mm / min. After the ingot blank is pulled out, the secondary cooling water is turned on, and the casting traction speed is gradually increased step by step according to 100 - 350 mm / min to cast the corrosion-resistant copper pipes described in the above technical solutions.

[0025] Adopting the above technical solution, the casting temperature is set at 1165°C ±5°C, which ensures that the molten copper has good fluidity, helps to reduce casting defects. At the same time, a phosphorus source is added to the molten copper. Phosphorus elements can significantly improve the corrosion resistance of the corrosion-resistant copper pipes, especially when used in humid, acidic or alkaline environments or seawater. Phosphorus elements can also react with oxygen elements in the molten copper to form phosphorus oxides, and phosphorus oxides are volatile and will escape at high temperatures, thus reducing the oxygen elements in the copper alloy. In addition to deoxidation, phosphorus can also react with other elements in the impurities to form compounds that are easy to separate from the molten copper, thereby further achieving the purpose of purifying the molten copper. The control of the flow rate of the primary cooling water in the crystallizer can not only effectively control the cooling rate of the molten copper, avoid internal stress and cracks caused by too fast cooling, but also ensure the rapid solidification of the corrosion-resistant copper pipes and improve production efficiency. Secondly, the gradual increase in speed from the initial 100 mm / min to 350 mm / min helps to dissipate heat evenly, reduce uneven deformation and internal stress accumulation, ensure the dimensional accuracy and surface quality of the corrosion-resistant copper pipes, is conducive to the uniform plastic deformation of the material, and improves the mechanical properties and pressure resistance of the corrosion-resistant copper pipes. Obtaining molten copper from the method for preparing oxygen-free copper pipes from recycled copper can effectively reduce the content of impurities, thereby eliminating cuprous oxide, reducing the potential difference between grain boundaries and within grains, and the corrosion-resistant copper pipes have excellent ant nest corrosion resistance.

[0026] Further, the traction program is: pull - stop - retreat - stop - retreat - stop - pull.

[0027] Adopting the above technical solution, through periodic stretching and retracting actions, the stress concentration inside the corrosion-resistant copper pipes can be reduced, and damage to the corrosion-resistant copper pipes caused by continuous stretching can be avoided. The two retreat and stop steps can also ensure that the molten copper is more evenly distributed, so as to improve the structural strength and quality of the corrosion-resistant copper pipes, and can also guarantee the service life of the corrosion-resistant copper pipes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the drawings:

[0029] Figure 1It is a flowchart of the method for preparing oxygen-free copper tubes from recycled copper in the present invention;

[0030] Figure 2 It is a schematic structural diagram of the device for preparing oxygen-free copper tubes from recycled copper in the present invention;

[0031] In the figure, 100 is a shaft furnace; 200 is a chute; 300 is a refining furnace; 400 is a holding furnace; 500 is a casting furnace. Detailed implementation manners

[0032] 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 with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention.

[0033] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above accompanying drawings are used to distinguish similar objects and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here.

[0034] It should be understood that in various embodiments of the present invention, such as the magnitude of the serial numbers of each process, it does not mean the sequence of execution is prior or subsequent. The execution sequence of each process should be determined by its function and internal logic and should not constitute any limitation to the implementation process of the embodiments of the present invention.

[0035] It should be understood that in the present invention, "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0036] It should be understood that in the present invention, "a plurality of" means two or more. "And / or" is only a description of the association relationship of associated objects, indicating that three relationships can exist. For example, X and / or Y can represent: X exists alone, X and Y exist simultaneously, and Y exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after. "Including X, Y and Z", "including X, Y, Z" means that all of X, Y, and Z are included, "including X, Y or Z" means including any one of X, Y, and Z, and "including X, Y and / or Z" means including any one or any two or all three of X, Y, and Z.

[0037] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined or replaced with each other according to actual conditions, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0038] Embodiment 1:

[0039] The present invention provides a corrosion-resistant copper tube, which controls the contents of oxygen, hydrogen and phosphorus in the corrosion-resistant copper tube. The oxygen content of the corrosion-resistant copper tube is less than 5ppm, and the hydrogen content is less than 0.3ppm, so that cuprous oxide in the corrosion-resistant copper tube produced by recycled copper can be effectively eliminated, and the potential difference between the grain boundary and the grain is reduced. The phosphorus content is 0.1% to 0.3%, and the remainder is copper, so that the corrosion-resistant copper tube produced by recycled copper significantly reduces the oxides and hydrogen embrittlement that may cause corrosion in the corrosion-resistant copper tube. In addition, the phosphorus content is accurately controlled, and the phosphorus element can significantly improve the corrosion resistance of the corrosion-resistant copper tube, especially when used in humid, acidic and alkaline or seawater. The appropriate phosphorus content can also ensure the strength and hardness of the corrosion-resistant copper tube. Secondly, the corrosion-resistant copper tube has fewer types of impurities, ensures a higher copper content, ensures good electrical conductivity and thermal conductivity of the material, and also retains the good processability of the copper itself, is suitable for various forming, drawing and welding processes, and is convenient for manufacturing pipe fittings of complex shapes. To make the corrosion-resistant copper tube performance: tensile strength is not less than 250MPa, the corrosion-resistant copper tube has a good ability to resist tensile damage, and is suitable for application scenarios with large external forces. Secondly, the yield strength is 60-80MPa, which helps to improve the forming performance of the corrosion-resistant copper tube, and the elongation is not less than 45%, which means that the copper tube has good plastic deformation ability and can withstand large deformation without breaking. Then, the solid residue is not more than 0.1mg / m, which means that there are few solid impurities remaining inside the corrosion-resistant copper tube, which helps to improve the purity and service life of the product. Next, the residual oil on the inner wall is not more than 0.15mg / m, so that the corrosion-resistant copper tube not only has good mechanical properties, but also has excellent corrosion resistance and processing performance, and is suitable for a variety of harsh application environments.

[0040] If the phosphorus content in the corrosion-resistant copper tube is too low, the corrosion-resistant copper tube is easy to corrode. If the phosphorus content in the corrosion-resistant copper tube is too high, the corrosion-resistant copper tube becomes brittle and hard, affecting its ductility and toughness, and may cause cracks during bending or forming. Preferably, the phosphorus content of the corrosion-resistant copper tube is 0.1% to 0.2%, which can reduce the phosphorus content in the corrosion-resistant copper tube as much as possible while ensuring the copper tube's resistance to anthill corrosion.

[0041] The phosphorus content and copper content mentioned in this article refer to the mass ratio, which is determined by measuring and calculating the mass of phosphorus and copper in the corrosion-resistant copper tube.

[0042] in, The corrosion depth of the 6.35×0.23×0.12mm seamless internally threaded corrosion-resistant copper tube in 0.01% formic acid can be less than 0.03mm. Of course, in corrosion-resistant copper tubes of other sizes, the corrosion depth can be even smaller.

[0043] Example 2:

[0044] As Figure 1 shown, the present invention provides a method for preparing oxygen-free copper tubes from recycled copper, which is mainly applicable to the processing of recycled copper materials. The recycled copper mainly contains oxygen element, hydrogen element, and other elemental impurities such as arsenic element, antimony element, bismuth element, iron element, lead element, tin element, nickel element, zinc element, sulfur element, etc. First of all, the oxygen element has oxidizing property. The oxygen element can react with the hydrogen element in the impurities through an oxidation-reduction reaction to generate water. And the copper liquid in the shaft furnace is heated to a set temperature. The relatively high temperature of the copper liquid can provide sufficient activation energy to promote a relatively fast reaction rate. The generated water will also be evaporated in the form of water vapor by heating, so that the hydrogen element content in the copper liquid can be reduced. At the same time, the oxygen element can also react with other elements in the impurities except the hydrogen element through an oxidation reaction to form oxides. The oxides are usually insoluble in the copper liquid but form a slag phase, which can be removed from the surface of the copper liquid by skimming the slag, thereby reducing the impurity content in the copper liquid. And the oxygen element itself is the impurity to be removed in the copper liquid, without introducing other impurity-removing agents, so the types of impurities in the copper liquid will not increase. And secondly, since the reducing gas has reducing property, the reducing gas can react with the oxygen element in the impurities through a reduction reaction to generate an oxygen-containing gas. The oxygen-containing gas is volatile, so that the oxygen element content in the copper liquid can be reduced. At the same time, the reducing gas can also react with other elements in the impurities except the oxygen element through a reduction reaction to generate substances separable from the copper liquid, further reducing the impurity content. And the temperature of the copper liquid is relatively high, and the impurities will still react with the oxygen element through an oxidation-reduction reaction to further reduce the impurity content. And since a high-concentration reducing gas is likely to form an explosive mixture when mixed with air, adding an inert gas can reduce the flammability range of this mixture and reduce potential safety hazards. And as the temperature of the copper liquid decreases, the solubility of the impurity content will also decrease, and it is more likely to precipitate from the copper liquid and react with the oxygen element to form a slag phase that is easy to separate, so that the impurities can be removed more thoroughly and the purity of the oxygen-free copper tube can be further improved.

[0045] Therefore, the method for preparing oxygen-free copper tubes from recycled copper in this embodiment includes the following steps:

[0046] S1: Heat the copper liquid in the shaft furnace to a set temperature, adjust the concentration of the reducing gas in the shaft furnace, so that the oxygen element content in the copper liquid in the shaft furnace is increased to more than 30 ppm, and perform primary impurity removal;

[0047] S2: The molten copper in the shaft furnace is successively passed into the chute, refining furnace, holding furnace, and casting furnace. The temperature of the molten copper in the chute, refining furnace, holding furnace, and casting furnace gradually decreases. Inert gas + reducing gas is introduced into the chute, refining furnace, holding furnace, and casting furnace, and the flow rate and pressure of the inert gas + reducing gas introduced into the chute, refining furnace, holding furnace, and casting furnace gradually decrease for secondary impurity removal to obtain oxygen-free copper tubes.

[0048] By reverse operation in S1, first increase the oxygen element content of the molten copper in the shaft furnace and raise the oxygen element content of the molten copper to be greater than 30 ppm. There can be enough oxygen elements to undergo oxidation reactions with impurities for primary impurity removal to ensure the impurity removal effect. If the oxygen element content of the molten copper in the shaft furnace is lower than 30 ppm, the impurity removal effect is poor, resulting in a still high impurity content in the molten copper, increasing the difficulty of impurity removal in subsequent processing steps. If the impurity removal ability in subsequent processing steps is weak, it may lead to the impurity content in the finally produced oxygen-free copper tubes still being higher than the target value, affecting the quality of the oxygen-free copper tubes.

[0049] In S2, the molten copper in the shaft furnace is successively passed into the chute, refining furnace, holding furnace, and casting furnace. The temperature of the molten copper in the chute, refining furnace, holding furnace, and casting furnace gradually decreases. Inert gas + reducing gas is introduced into the chute, refining furnace, holding furnace, and casting furnace. The oxygen element in the molten copper is gradually reduced by the reducing gas successively passing through the chute, refining furnace, holding furnace, and casting furnace, and the impurities in the molten copper are gradually removed. Through multiple steps of impurity removal for the molten copper, it is also possible to achieve refined control of the process of removing hydrogen and deoxygenating elements, obtaining secondary impurity removal, and being able to better control the impurity content in the molten copper. And when the impurity content enters the next furnace after being removed by the previous furnace, the content will decrease. Correspondingly, the required amount of reducing gas can also decrease, causing the flow rate and pressure of the inert gas + reducing gas introduced into the chute, refining furnace, holding furnace, and casting furnace to gradually decrease. The gradually decreasing flow rate and pressure of the inert gas + reducing gas help control the overflow of bubbles in the molten copper, reduce the formation of pores, and can also ensure that the effect of removing hydrogen and deoxygenating is always within the set range. At the same time, it also helps control the stirring degree of the molten copper, ensure the effective progress of oxidation slag formation, improve the quality of oxygen-free copper tubes produced from recycled copper, reduce energy consumption, and improve process efficiency.

[0050] It should be noted that the reducing gas can react with the oxides in the molten copper. By adjusting the concentration of the reducing gas in the shaft furnace to adjust the oxygen element content in the molten copper, such as by reducing the use of high-carbon fuels and switching from coal or coke to low-carbon fuels or clean energy for control, reducing the reducing gas can cause more oxygen elements to remain in the molten copper rather than being reduced by the reducing gas, so that the oxygen element content of the molten copper in the shaft furnace can be raised to be greater than 30 ppm. Of course, oxygen-containing gas can also be directly introduced to change the oxygen element content of the molten copper.

[0051] Specifically, the concentration of the reducing gas in the shaft furnace, launder, refining furnace, holding furnace, and casting furnace gradually increases from 2% to 5%. By gradually increasing the concentration of the reducing gas, the removal process of impurities can be more precisely controlled, avoiding problems such as over-oxidation or insufficient oxidation. If the concentration of the reducing gas is less than 2.0%, the lower concentration of the reducing gas may lead to a decrease in the reduction efficiency of impurities, prolong the production cycle, and may not effectively remove the impurities in the reduced copper, thus affecting the quality of the oxygen-free copper tube. If the concentration of the reducing gas is greater than 5%, a higher concentration of the reducing gas may require more energy for heating and mixing, thereby increasing energy consumption. Using an excessive amount of the reducing gas not only wastes resources but also increases the raw material cost.

[0052] Preferably, the concentration of the reducing gas in the shaft furnace is 2% - 3%, which raises the oxygen element content in the copper liquid in the shaft furnace to more than 30 ppm to effectively remove the hydrogen element in the copper liquid, making the hydrogen element content in the copper liquid lower than the set value. The set value of the hydrogen element content is less than 0.5 ppm, so that in the subsequent treatment steps, it is easier to further reduce the hydrogen element content to the target value. The target value of the hydrogen element content is less than 0.3 ppm. The concentration of the reducing gas in the launder is maintained at 3% - 4%. By gradually increasing the concentration of the reducing gas, the reducing atmosphere in the copper liquid can be precisely controlled, optimizing the removal process of impurities in the copper liquid. Among them, the impurities in the copper liquid can be significantly reduced in the shaft furnace and the launder, basically meeting the quality requirements of the oxygen-free copper tube. In the subsequent refining furnace, holding furnace, and casting furnace, the impurities are further removed, but the effect is not very obvious. Therefore, the concentration of the reducing gas in the subsequent refining furnace, holding furnace, and casting furnace only needs to gradually increase from 4% to 5%.

[0053] In order to make the inert gas + reducing gas enter the copper liquid more uniformly, permeable bricks are installed in the launder, refining furnace, holding furnace, and casting furnace. The appropriate number of permeable bricks can be selected according to the flow rate and pressure of the inert gas + reducing gas introduced, so that the inert gas + reducing gas is evenly distributed in the copper liquid, reducing the phenomenon of local supersaturation. When the flow rate and pressure of the inert gas + reducing gas are relatively large, more permeable bricks are needed to ensure uniform gas distribution; when the flow rate and pressure of the inert gas + reducing gas are relatively small, fewer permeable bricks are sufficient.

[0054] In this embodiment, 7 permeable bricks are installed at the bottom of the launder, 6 permeable bricks are installed at the bottom of the refining furnace, 5 permeable bricks are installed at the bottom of the holding furnace, and 4 permeable bricks are installed at the bottom of the casting furnace. The number of permeable bricks is adjusted according to the actual production requirements and product quality feedback, saving energy and cost while maintaining production efficiency.

[0055] It should be noted that 2, 3, 4, 5, 6, 7, 8, 9 or other appropriate numbers of permeable bricks can also be installed at the bottoms of the launder, refining furnace, holding furnace, and casting furnace.

[0056] It is understandable that in other embodiments, permeable bricks of different sizes can also be selected to adapt to the flow rate and pressure of the inert gas + reducing gas introduced.

[0057] Furthermore, the flow rate of the inert gas + reducing gas introduced into the launder, refining furnace, holding furnace, and casting furnace gradually decreases within the range of 10 - 30 L / min, and the pressure of the inert gas + reducing gas gradually decreases within the range of 0.1 - 0.5 MPa. While ensuring that the effect of removing hydrogen and deoxidizing elements in the launder, refining furnace, holding furnace, and casting furnace is always within the set range, energy consumption is reduced. If the flow rate of the inert gas + reducing gas is greater than 30 L / min, the excessive flow rate may cause unstable flow of the inert gas + reducing gas, resulting in instability in the preparation process of oxygen-free copper tubes. This also means that more energy is required to supply the inert gas + reducing gas, increasing production costs. If the flow rate of the inert gas + reducing gas is less than 10 L / min, the effect of hydrogen and oxygen removal cannot reach the set range, resulting in poor quality of the produced oxygen-free copper tubes. If the pressure of the inert gas + reducing gas is greater than 0.5 MPa, the speed of the inert gas + reducing gas passing through the copper liquid is too fast, reducing the contact time between the inert gas + reducing gas and the copper liquid and affecting the effect of hydrogen and oxygen removal. If the pressure of the inert gas + reducing gas is less than 0.1 MPa, the inert gas + reducing gas cannot effectively enter the copper liquid, thus reducing its effect of hydrogen and oxygen removal.

[0058] Among them, S2 can be refined into the following steps. First, through each permeable brick, an inert gas + reducing gas is blown into the launder from the bottom of the launder. The flow rate of the inert gas + reducing gas blown through each permeable brick is 25 - 30 L / min, and the pressure of the inert gas + reducing gas is 0.3 - 0.5 MPa, so that the oxygen element content in the copper liquid in the launder is less than 20 ppm and the hydrogen element content is less than 0.4 ppm, which can ensure efficient impurity removal.

[0059] Secondly, since the oxygen element content in the copper liquid entering the refining furnace is lower than that in the copper liquid entering the launder, through each permeable brick, an inert gas + reducing gas is blown into the refining furnace from the bottom of the refining furnace. The flow rate of the inert gas + reducing gas blown through each permeable brick is 20 - 25 L / min, and the pressure of the inert gas + reducing gas is 0.2 - 0.3 MPa, so that the oxygen element content in the copper liquid in the refining furnace is less than 10 ppm and the hydrogen element content is less than 0.4 ppm, meeting the requirements for deoxidation, effectively controlling the use of the inert gas + reducing gas, and taking into account production efficiency and cost - effectiveness.

[0060] Next, since the oxygen element content in the copper liquid entering the holding furnace is lower than that in the copper liquid entering the refining furnace, inert gas + reducing gas is blown into the holding furnace from the bottom of the holding furnace through each porous plug. The flow rate of the inert gas + reducing gas blown into each porous plug is 15 - 20 L / min, and the pressure of the inert gas + reducing gas is 0.15 - 0.2 MPa, so that the oxygen element content in the copper liquid in the holding furnace is less than 5 ppm and the hydrogen element content is less than 0.3 ppm, meeting the requirements for deoxidation, effectively controlling the use of the inert gas + reducing gas, avoiding over-treatment and energy waste, and further taking into account production efficiency and cost-effectiveness.

[0061] Finally, since the oxygen element content in the copper liquid entering the casting furnace is lower than that in the copper liquid entering the holding furnace, inert gas + reducing gas is blown into the casting furnace from the bottom of the casting furnace through each porous plug. The flow rate of the inert gas + reducing gas blown into each porous plug is 10 - 15 L / min, and the pressure of the inert gas + reducing gas is 0.1 - 0.15 MPa, so that the oxygen element content in the copper liquid in the casting furnace is less than 5 ppm and the hydrogen element content is less than 0.3 ppm, meeting the requirements for deoxidation, effectively controlling the use of the inert gas + reducing gas, avoiding over-treatment and energy waste, and further taking into account production efficiency and cost-effectiveness. In the final treatment stage before casting, a low-oxygen and low-hydrogen environment is maintained to ensure that the purity of the copper liquid will not be reduced due to external factors during the process of entering the mold and solidifying, thus improving the quality of the copper tube.

[0062] It should be noted that the flow rate and pressure of the inert gas + reducing gas in the chute, refining furnace, holding furnace, and casting furnace are not necessarily as described above, and other values can also be used as long as the hydrogen and oxygen element contents in the final copper liquid are lower than the set values.

[0063] Furthermore, the set temperature of the molten copper in the shaft furnace in S1 is maintained at 1200 ± 20 °C, the temperature of the molten copper in the launder in S2 is maintained at 1190 ± 20 °C, the temperature of the molten copper in the refining furnace can also be 1180 ± 20 °C, the temperature of the molten copper in the holding furnace can also be 1170 ± 20 °C, and the temperature of the molten copper in the casting furnace can be 1160 ± 10 °C. It is necessary to ensure that the temperatures of the molten copper in the shaft furnace, launder, refining furnace, holding furnace, and casting furnace gradually decrease within the range of 1220 - 1150 °C. A higher temperature in the shaft furnace is conducive to rapid reactions and the removal of most impurities in the molten copper. As the temperature of the molten copper gradually decreases and enters the launder, the solubility of impurities will decrease, and they are more likely to precipitate from the molten copper and react with oxygen to form oxides that are easy to separate, which helps the precipitation of oxides. This can remove these more thoroughly and improve the purity of copper. The step-by-step adjustment of the process flow is conducive to precisely controlling the chemical composition and physical state of the molten copper, reducing the influence of thermal stress on the microstructure of the molten copper. The finally produced copper material has a more uniform composition, fewer inclusions, and better physical properties. If the temperature of the molten copper is higher than 1220 °C, the excessive temperature may promote the dissolution of impurities and affect the purity of the oxygen-free copper tube. If the temperature of the molten copper is lower than 1150 °C, the too low temperature may slow down the oxidation process of impurities, reduce the slag-making efficiency, and result in a higher impurity content in the oxygen-free copper tube.

[0064] Preferably, the reducing gas is CO. CO is a powerful reducing agent that can react with the oxides in the molten copper, reduce them to metallic copper, effectively remove the oxides in the molten copper, and improve the purity of the recycled copper. The CO reduction process is relatively mild and will not violently change the properties of the molten copper, which is conducive to maintaining the stability of the molten copper and facilitating subsequent refining, casting and other processing steps, improving the efficiency of the entire production chain and the product quality. Compared with other noble metal catalysts or complex chemical reagents, CO is a common industrial gas with relatively low cost. Using CO as a reducing agent can effectively control the production cost. Finally, the presence of CO can also reduce the solubility of hydrogen in the molten copper, prompting hydrogen to precipitate in the form of bubbles, which helps to efficiently remove hydrogen and reduce the hydrogen embrittlement phenomenon of copper products, improving their mechanical properties and service life.

[0065] It should be noted that the components of other elements in the recycled copper except hydrogen and oxygen elements are shown in Table 1:

[0066] Table 1 Contents of Other Elements in the Impurities of Recycled Copper Except Hydrogen and Oxygen Elements

[0067]

[0068] In order to remove elements other than hydrogen and oxygen from the impurities of recycled copper, the temperature of the copper liquid in the shaft furnace is preferably 1200 °C. With the CO concentration in the shaft furnace being 2%, impurities such as Bi, Sb, As, Fe, Ni, Pb, Sn, S, and Zn are removed by oxidation slagging. The composition of the obtained recycled copper is shown in Table 2:

[0069] Table 2 Content of elements other than hydrogen and oxygen in the impurities of the copper liquid in the shaft furnace

[0070]

[0071] Through the regulation of the CO concentration in the launder being 3.0%, the temperature of the copper liquid is preferably 1190 °C. Impurities such as Bi, Sb, As, Fe, Ni, Pb, Sn, S, and Zn are further removed by oxidation slagging. The composition of the obtained recycled copper is shown in Table 3:

[0072] Table 3 Content of elements other than hydrogen and oxygen in the impurities of the copper liquid in the launder

[0073]

[0074] Using this process, after the copper liquid is treated in the launder, the contents of impurities such as Bi, Sb, As, Fe, Ni, Pb, Sn, S, and Zn already meet the quality requirements of oxygen-free copper tubes. Subsequently, after the copper liquid is treated in the refining furnace, the holding furnace, and the casting furnace, the changes in the contents of impurities such as Bi, Sb, As, Fe, Ni, Pb, Sn, S, and Zn are relatively small and the detection difficulty is relatively large. In order to further optimize the quality of oxygen-free copper tubes, it is no longer recorded in a table.

[0075] Next, through the regulation of the CO concentration in the refining furnace being 3.5%, the temperature of the copper liquid is preferably 1180 °C. Impurities such as Bi, Sb, As, Fe, Ni, Pb, Sn, S, and Zn are further removed by oxidation slagging.

[0076] Then, through the regulation of the CO concentration in the holding furnace being 4%, the temperature of the copper liquid is preferably 1170 °C. Impurities such as Bi, Sb, As, Fe, Ni, Pb, Sn, S, and Zn are further removed by oxidation slagging.

[0077] Finally, through the regulation of the CO concentration in the casting furnace being 4.5%, the temperature of the copper liquid is preferably 1160 °C. Impurities such as Bi, Sb, As, Fe, Ni, Pb, Sn, S, and Zn are further removed by oxidation slagging.

[0078] After the above steps, the gradual cooling and step-by-step refining of the copper liquid can be achieved. The high-temperature stage is carried out in the refining furnace, which is conducive to rapid reactions and the removal of most impurities; as the temperature gradually decreases and enters the static furnace, it helps with the precipitation of impurities and further purification; finally, maintaining a relatively low temperature in the casting furnace helps to stabilize the composition of the copper liquid and reduce casting defects.

[0079] It should be noted that the concentration of the reducing gas mentioned in this article refers to the volume ratio, which is obtained by measuring and calculating the volume of the reducing gas in the shaft furnace, chute, refining furnace, static furnace, and casting furnace. The contents of hydrogen element, oxygen element, impurities, etc. mentioned in this article refer to the mass ratio, which is determined by measuring and calculating the mass of hydrogen element, oxygen element, and impurities in the copper liquid.

[0080] For other content not described in this embodiment, reference can be made to the above embodiments.

[0081] Embodiment 3:

[0082] As Figure 2 shown, the present invention provides a device for preparing oxygen-free copper tubes from recycled copper, including a shaft furnace 100, a chute 200, a refining furnace 300, a static furnace 400, and a casting furnace 500. The chute 200, refining furnace 300, static furnace 400, and casting furnace 500 are all installed with gas-permeable bricks at the bottom for blowing in inert gas + reducing gas. To implement the method for preparing oxygen-free copper tubes from recycled copper in the above embodiment, it can be based on the flow rate and pressure of the inert gas + reducing gas introduced into the chute 200, refining furnace 300, static furnace 400, and casting furnace.

[0083] For other content not described in this embodiment, reference can be made to the above embodiments.

[0084] Embodiment 4:

[0085] In this embodiment, a casting process for corrosion-resistant copper tubes is provided. The recycled copper raw materials are cast with the copper liquid obtained from the casting furnace of the method for preparing oxygen-free copper tubes from recycled copper according to any one of the above, which can effectively reduce the content of impurities, thereby eliminating cuprous oxide, reducing the potential difference between grain boundaries and within grains, and the corrosion-resistant copper tubes have excellent ant nest corrosion resistance. Secondly, a phosphorus source is added to the copper liquid. The phosphorus element can significantly improve the corrosion resistance of the copper tubes, especially when used in humid, acidic or alkaline environments or seawater. The phosphorus element can also react with the oxygen element in the copper liquid to form oxides of the phosphorus element, and the oxides of the phosphorus element are volatile and will escape at high temperatures, thereby reducing the oxygen content in the copper alloy. In addition to deoxidation, the phosphorus element can also react with other elements in the impurities to form compounds that are easy to separate from the copper liquid, thereby further achieving the purpose of purifying the copper liquid. The casting temperature of the copper liquid is 1165°C ± 5°C, which ensures good fluidity of the copper liquid, helps reduce casting defects, and at the same time ensures the uniform distribution of alloys such as phosphorus. Then, the primary cooling water flow rate of the crystallizer is 45 - 55 L / min, which can not only effectively control the cooling rate of the copper liquid, avoid internal stress and cracks caused by too fast cooling, but also ensure the rapid solidification of the corrosion-resistant copper tubes and improve production efficiency. A traction program is adopted. In the traction program, the starting pulling speed during casting is 100 mm / min. After pulling out the ingot blank, secondary cooling water is turned on, and the casting traction speed is gradually increased from 100 mm / min to 350 mm / min. Casting to obtain the corrosion-resistant copper tubes of Example 1 helps uniform heat dissipation, reduces uneven deformation and internal stress accumulation, ensures the dimensional accuracy and surface quality of the corrosion-resistant copper tubes, is beneficial to the uniform plastic deformation of the material, and improves the mechanical properties and pressure resistance of the corrosion-resistant copper tubes.

[0086] Preferably, the casting traction speed is gradually increased from 100 mm / min, 170 mm / min, 200 mm / min, 250 mm / min, 300 mm / min, 330 mm / min, 350 mm / min.

[0087] Among them, the traction program is: pull - stop - retreat - stop - retreat - stop - pull. Through periodic stretching and retracting actions, the stress concentration inside the corrosion-resistant copper tubes can be reduced, and damage to the corrosion-resistant copper tubes caused by continuous stretching can be avoided. The two retreat-stop steps can also ensure more uniform distribution of the copper liquid to improve the structural strength and quality of the corrosion-resistant copper tubes, and can also ensure the service life of the corrosion-resistant copper tubes.

[0088] It can be understood that in other embodiments, the traction program can also be the common pull - stop - retreat - stop - pull, with simpler steps and higher production efficiency.

[0089] It should be noted that phosphorus-containing copper tubes can be obtained by directly adding pre-alloyed phosphorus copper ingots or phosphorus copper wires to the molten copper liquid. Of course, additives in the form of phosphorus copper particles or powders can also be used, which can be directly sprinkled into the copper liquid. In addition, copper alloy master alloys with a high phosphorus content can be melted and added to the copper liquid. Of course, the method of adding phosphorus is not limited to this.

[0090] For other content not described in this embodiment, reference can be made to the above embodiments.

[0091] In addition to the above preferred embodiments, there are other implementation manners of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a corrosion-resistant copper tube from recycled copper, characterized in that: The following steps are involved: S1: The copper liquid in the vertical furnace is heated to a set temperature, and the concentration of the reducing gas CO in the vertical furnace is adjusted to increase the oxygen content of the copper liquid in the vertical furnace to more than 30 ppm, and primary impurity removal is performed; S2: The molten copper in the vertical furnace is sequentially introduced into a chute, a refining furnace, a static furnace, and a casting furnace. The temperature of the molten copper in the chute, the refining furnace, the static furnace, and the casting furnace gradually decreases. Inert gas + reducing gas are introduced into the chute, the refining furnace, the static furnace, and the casting furnace. The flow rate and pressure of the inert gas + reducing gas introduced into the chute, the refining furnace, the static furnace, and the casting furnace gradually decrease, and secondary impurity removal is performed; S3: adding a phosphorus source to the copper liquid in the casting furnace, wherein the casting temperature of the copper liquid is 1165°C±5°C, the primary cooling water flow rate of the crystallizer is 45-55L / min, and a traction program is adopted. In the traction program, the casting pulling speed is 100mm / min, and the secondary cooling water is turned on after the ingot is pulled out. The casting traction speed is gradually increased within 100-350mm / min to prepare a corrosion-resistant copper tube.

2. The method for preparing a corrosion-resistant copper tube from recycled copper according to claim 1, characterized in that: The reducing gas concentration in the vertical furnace, chute, refining furnace, static furnace and casting furnace increases gradually.

3. The method for preparing a corrosion-resistant copper tube from recycled copper according to claim 2, characterized in that: The reducing gas concentration in the vertical furnace, chute, refining furnace, static furnace and casting furnace is gradually increased from 2 to 5%.

4. The method for preparing a corrosion-resistant copper tube from recycled copper according to claim 2, characterized in that: The temperature of the molten copper in the vertical furnace, chute, refining furnace, static furnace and casting furnace gradually decreases from 1220 to 1150°C.

5. The method for preparing a corrosion-resistant copper tube from recycled copper according to claim 1, characterized in that: The traction procedure is: pull-stop-retract-stop-retract-stop-pull.

6. Corrosion-resistant copper tube, characterized in that: A corrosion-resistant copper tube is produced by the method for preparing a corrosion-resistant copper tube from recycled copper as described in any one of claims 1 to 5, wherein the corrosion-resistant copper tube has an oxygen content of less than 5 ppm, a hydrogen content of less than 0.3 ppm, a phosphorus content of 0.1% to 0.3%, and the remainder is copper.

7. The corrosion-resistant copper tube according to claim 6, characterized in that: The corrosion-resistant copper tube has a tensile strength of not less than 250 MPa, a yield strength of 60-80 MPa, an elongation of not less than 45%, a solid residue of not more than 0.1 mg / m, and an inner wall residual oil of not more than 0.15 mg / m.

8. A device for preparing corrosion-resistant copper tubes from recycled copper, characterized in that: The invention comprises a vertical furnace, a chute, a refining furnace, a static furnace and a casting furnace, wherein the chute, the refining furnace, the static furnace and the casting furnace are all provided with air-permeable bricks at the bottom for blowing in inert gas + reducing gas, so as to realize the method for preparing corrosion-resistant copper tubes from recycled copper as described in any one of claims 1 to 5.

Images