Preparation method of easy-to-process continuous casting and rolling low-oxygen copper rod

Abstract

The invention belongs to the technical field of nonferrous metallurgy, and particularly discloses a preparation method of a continuous casting and rolling low-oxygen copper rod easy to machine. The preparation method of the low-oxygen copper rod comprises the following steps that copper and rare earth metal are mixed and smelted in a vacuum smelting furnace, the smelted and mixed metal is made into alloy particles, and then the alloy particles are ground into refining agent powder through high-pressure gas; and adding the refining agent powder into molten copper, cooling to prepare a cast ingot, and rolling to obtain the low-oxygen copper rod. The refining agent contains high-content rare earth metal with an improved proportion, the content of impurity elements and oxygen elements in molten copper can be reduced, meanwhile, trace rare earth elements are dissolved in a matrix and serve as crystallization nucleation points in the casting process, the crystallization process is accelerated, the as-cast structure is refined, and therefore the subsequent deformation performance is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nonferrous metallurgy, in particular to a preparation method of an easy-to-process continuous casting and rolling low-oxygen copper rod. BACKGROUND

[0002] Copper is widely used in various industrial sectors due to its excellent comprehensive performance, such as electrical conductivity, thermal conductivity, corrosion resistance, etc. The presence of a small amount of impurities such as oxygen, iron, antimony, tin, etc. can seriously affect the electrical conductivity and other properties of copper, so different fields have strict requirements for the purity of copper. Low-oxygen copper rods are favored by the market and widely used due to their high purity, low oxygen content and few impurities.

[0003] The low-oxygen copper rod produced by vertical furnace + continuous casting and rolling can be drawn to a minimum wire diameter of 0.1 mm, and it is easy to break during the drawing of "double zero" copper wire, affecting the quality and efficiency of drawing. The main reasons are: 1. A small amount of Fe, Sn, Zn and other impurities exist in the copper rod in the form of oxides in the matrix, which easily form crack sources during the drawing process, resulting in broken wire phenomenon; 2. The low-oxygen copper rod contains 200-400 ppm of oxygen elements, mainly in the form of copper oxide and cuprous oxide in the matrix, which become crack sources; 3. The purity of copper water is very high, and there are not enough crystal nucleation points during the casting process, resulting in coarse casting structure, affecting the subsequent rolling and stretching structure.

[0004] Therefore, it is urgent to develop a new low-oxygen copper rod preparation technology to improve the deformation performance of the copper rod and overcome the problem of easy breaking during the drawing of "double zero" copper wire of the continuous casting and rolling low-oxygen copper rod. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a preparation method of an easy-to-process continuous casting and rolling low-oxygen copper rod. The present application uses vacuum melting and high-pressure gas powdering technology to prepare Cu-Re refining agent, which can reduce oxidation loss, improve refining effect and reduce production cost; then the superfine Cu-Re refining agent powder is uniformly sprayed into the copper water by high-purity high-pressure nitrogen gas, which increases the acting volume and improves the refining efficiency; the refining agent of the present application contains high-content rare earth metals with improved ratio, which can better reduce the oxygen content and impurity content of the copper water, improve the quality of the copper rod, and accelerate the nucleation of the crystal grains as nucleation points, and refine the casting structure of the copper rod.

[0006] In a first aspect of the present application, a preparation method of a low-oxygen copper rod is provided, comprising the following steps:

[0007] S1, mix copper and rare earth metals according to the mass ratio of (52-64):(32-48), melt in a vacuum melting furnace, make alloy particles from the melted mixed metals, and then use high-pressure gas grinding to make refining agent powder;

[0008] S2, the refining agent powder is added into the copper water, and the copper ingot is cooled and rolled to obtain the low-oxygen copper rod.

[0009] The rare earth metal includes light rare earth and heavy rare earth; and the powder of the refining agent has an average particle size ranging from 3 to 10 μm.

[0010] According to some embodiments of the present application, the light rare earth includes praseodymium and neodymium, and the heavy rare earth includes gadolinium and holmium.

[0011] According to some embodiments of the present application, the rare earth metal includes praseodymium, neodymium, gadolinium and holmium.

[0012] According to some embodiments of the present application, the mass ratio of praseodymium, neodymium, gadolinium and holmium is (8-12):(8-12):(8-12):(8-12).

[0013] According to some embodiments of the present application, in step S1, the melting condition is that the melting temperature is 1250-1350℃, the preheating vacuum degree is 8-10 pa, the melting vacuum degree is 800-1000 pa, and the melting time is 3-5 h.

[0014] According to some embodiments of the present application, in step S1, the alloy particles are prepared by a rotating water-cooling disc, and the particle size of the alloy particles is less than 1 mm.

[0015] According to some embodiments of the present application, in step S1, the high-pressure gas mill is used to prepare the refining agent powder, and the working pressure is 1.0-1.5 Mpa, and the mill chamber pressure is 0.08-0.15 Mpa; the average particle size of the prepared refining agent powder is 5-10 μm.

[0016] According to some embodiments of the present application, in step S2, the method for adding the refining agent powder into the copper water is that the high-pressure high-purity nitrogen gas is used to uniformly spray the refining agent powder into the copper water, the nitrogen gas pressure is 2-4 Mpa, and the nitrogen gas purity is ≥99.99%.

[0017] According to some embodiments of the present application, in step S2, the adding amount of the refining agent powder is m=(0.08-0.12)*M*n (kg), wherein M is the copper water flow (T / h), and n is the oxygen content in the copper water (ppm).

[0018] The second aspect of the present application provides a refining agent for preparing a low-oxygen copper rod, wherein the components of the refining agent include copper, praseodymium, neodymium, gadolinium and holmium, the mass ratio of each component is (52-64):(8-12):(8-12):(8-12):(8-12), and the average particle size of the refining agent is 3-10 μm.

[0019] According to some embodiments of the present invention, the refining agent is prepared according to step S1 of the method for preparing low-oxygen copper rods as described in the first aspect of the present invention.

[0020] The beneficial effects of this invention are:

[0021] This invention employs vacuum melting and high-pressure gas powdering technology to prepare a Cu-Re alloy refining agent with high rare earth metal content. The refining agent powder is uniformly sprayed into molten copper using high-purity, high-pressure nitrogen addition technology, which improves refining efficiency, achieving both impurity removal and oxygen reduction while lowering production costs. The alloy refining agent utilized in this invention has specific light and heavy rare earth metal components. Besides better impurity removal and oxygen reduction, these trace rare earth metal elements can also act as more suitable nucleation sites in molten copper, accelerating grain nucleation, refining the casting structure of the copper rod, and enhancing its deformation capability. Simultaneously, the trace amounts of praseodymium, neodymium, gadolinium, and holmium metals have negligible impact on conductivity, unlike traditional zinc, tin, and iron metals. The low-oxygen copper rod ultimately prepared by this invention exhibits excellent deformation performance and is less prone to breakage during the drawing of "double-zero" copper wire, meeting the market demand for high-quality low-oxygen copper rods.

[0022] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0024] Figure 1 This is a process flow diagram for preparing "double-zero" copper wire using low-oxygen copper rods according to the present invention;

[0025] Figure 2 This is a metallographic diagram of the low-oxygen copper rod of Embodiment 1 of the present invention;

[0026] Figure 3 The tensile stress-strain curve of the copper wire prepared from the low-oxygen copper rod of Example 1 of the present invention. Detailed Implementation

[0027] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0028] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0029] Example 1

[0030] This embodiment provides a method for preparing easily machinable continuously cast and rolled low-oxygen copper rods, the specific steps of which are as follows:

[0031] Preparation of refining agent:

[0032] 1) Mix pure copper, praseodymium, neodymium, gadolinium, and holmium (purity above 99.9%) in a mass ratio of 60:10:10:10:10 and melt them in a vacuum melting furnace. Set the vacuum melting conditions as follows: temperature 1300℃, preheating vacuum degree 9pa, vacuum degree 900pa, and melting time 4h.

[0033] 2) Pour the molten mixed metal liquid onto a rotating water-cooling plate to prepare small alloy particles with a diameter of less than 1 mm; wherein the water-cooling plate is made of copper, and the inlet temperature is set to 28℃ (less than 30℃) and the outlet temperature is set to 36℃ (less than 38℃).

[0034] 3) Place small alloy balls in a high-pressure gas mill and use a high-pressure air gun to accelerate particle collision and break the particles. Use the high-pressure gas at the bottom to screen out alloy powder of suitable particle size and collect it in a sealed container, which is the refining agent. The working fluid pressure is 1.3 MPa, the mill chamber pressure is 0.12 MPa, and the average particle size of the refining agent powder is 7.2 μm.

[0035] Preparation of low-oxygen copper rods:

[0036] 4) Add the pure electrolytic plate into the vertical furnace and heat it to 1250℃ using natural gas combustion to melt it into molten copper; the molten copper enters the holding furnace through the natural gas-heated chute, and the oxygen content of the molten copper is tested to be 250ppm;

[0037] 5) High-pressure, high-purity nitrogen gas is used to uniformly spray the refining agent powder in the sealed tank into the molten copper; wherein, the nitrogen pressure is 3 MPa, the nitrogen purity is ≥99.99%, the refining agent injection rate is m=0.1*M*n, where m is in kg / h, M is the molten copper flow rate (T / h), and n is the oxygen content in the molten copper (ppm).

[0038] 6) Pour the molten copper with added refining agent into a water-cooled casting mold to prepare ingots. Then, through a continuous rolling system, produce high-performance 8mm low-oxygen copper rods.

[0039] Example 2

[0040] This embodiment provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0041] This embodiment is basically the same as Embodiment 1, except that the mass ratio of copper, praseodymium, neodymium, gadolinium and holmium raw materials in the refining agent components of this embodiment is 52:12:12:12:12.

[0042] Finally, an 8mm low-oxygen copper rod was produced.

[0043] Example 3

[0044] This embodiment provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0045] This embodiment is basically the same as Embodiment 1, except that the mass ratio of copper, praseodymium, neodymium, gadolinium and holmium raw materials in the refining agent components of this embodiment is 64:9:9:9:9.

[0046] Finally, an 8mm low-oxygen copper rod was produced.

[0047] Example 4

[0048] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0049] This embodiment is basically the same as Embodiment 1, except that in step 5) of this comparative example, the amount of refining agent injected is m = 0.12 * M * n.

[0050] Finally, an 8mm low-oxygen copper rod was produced.

[0051] Example 5

[0052] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0053] This embodiment is basically the same as Embodiment 1, except that in step 5) of this comparative example, the amount of refining agent injected is m = 0.08 * M * n.

[0054] Finally, an 8mm low-oxygen copper rod was produced.

[0055] Comparative Example 1

[0056] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0057] This comparative example is basically the same as Example 1, except that the mass ratio of copper, praseodymium, neodymium, gadolinium and holmium raw materials in the refining agent components of this comparative example is 80:5:5:5:5.

[0058] Finally, an 8mm low-oxygen copper rod was produced.

[0059] Comparative Example 2

[0060] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0061] This comparative example is basically the same as Example 1, except that the mass ratio of copper, praseodymium, neodymium, gadolinium and holmium raw materials in the refining agent components of this comparative example is 40:15:15:15:15.

[0062] Finally, an 8mm low-oxygen copper rod was produced.

[0063] Comparative Example 3

[0064] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0065] This comparative example is basically the same as Example 1, except that the refining agent components in this comparative example only use copper, praseodymium and neodymium, in a mass ratio of 60:20:20.

[0066] Finally, an 8mm low-oxygen copper rod was produced.

[0067] Comparative Example 4

[0068] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0069] This comparative example is basically the same as Example 1, except that the refining agent components used in this comparative example are only copper, gadolinium and holmium, in a mass ratio of 60:20:20.

[0070] Finally, an 8mm low-oxygen copper rod was produced.

[0071] Comparative Example 5

[0072] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0073] This comparative example is basically the same as Example 1, except that the refining agent components in this comparative example only use copper, cerium, and lanthanum in a mass ratio of 60:20:20.

[0074] Finally, an 8mm low-oxygen copper rod was produced.

[0075] Comparative Example 6

[0076] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0077] This comparative example is basically the same as Example 1. In this comparative example, only copper, cerium and lanthanum are used in the refining agent components, with a mass ratio of 60:20:20. It is prepared by conventional atmospheric melting method and added for refining in block form.

[0078] Comparative Example 7

[0079] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0080] This comparative example is basically the same as Example 1, except that in step 5) of this comparative example, the amount of refining agent injected is m = 0.15 * M * n.

[0081] Finally, an 8mm low-oxygen copper rod was produced.

[0082] Comparative Example 8

[0083] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0084] This comparative example is basically the same as Example 1, except that in step 5) of this comparative example, the amount of refining agent injected is m = 0.05 * M * n.

[0085] Finally, an 8mm low-oxygen copper rod was produced.

[0086] Comparative Example 9

[0087] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0088] This comparative example is basically the same as Example 1, except that in step 3) of this comparative example, a refining agent powder with an average particle size of 3.2 μm is prepared by adjusting the grinding chamber pressure.

[0089] Finally, an 8mm low-oxygen copper rod was produced.

[0090] Comparative Example 10

[0091] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0092] This comparative example is basically the same as Example 1, except that in step 3) of this comparative example, a refining agent powder with an average particle size of 12.2 μm is prepared by adjusting the grinding chamber pressure.

[0093] Finally, an 8mm low-oxygen copper rod was produced.

[0094] Comparative Example 11

[0095] This comparative example provides a method for preparing an easily machinable, continuously cast and rolled low-oxygen copper rod.

[0096] The difference between this comparative example and Example 1 is that no refining agent was added to the molten copper in step 5) of this comparative example.

[0097] Finally, an 8mm low-oxygen copper rod was produced.

[0098] Table 1 shows a comparison of the process parameters for the above embodiments and comparative examples.

[0099] Preparation example: Low-oxygen copper rods prepared in each example and comparative example were used to draw "double-zero" copper wires using conventional processes. The process flow diagram is shown below. Figure 1 As shown.

[0100] Testing and inspection: The "double zero" copper wires prepared from the low-oxygen copper rods of each embodiment and comparative example were subjected to performance testing, including average grain size, tensile strength, resistivity, oxygen content, and minimum wire diameter.

[0101] The test results are shown in Table 2. The metallographic structure of the low-oxygen copper rod prepared in Example 1 is as follows: Figure 2 As shown, the tensile stress-strain curve of the copper wire is as follows: Figure 3 As shown.

[0102] The test results above show that the high-rare-earth metal content Cu-Re alloy refining agent prepared by adding rare-earth elements praseodymium, neodymium, gadolinium, and holmium through vacuum melting and high-pressure gas powdering technology can effectively refine the grain structure of copper rods, improve tensile strength, reduce oxygen content, and enhance wire drawing performance, without significantly affecting resistivity. This is because vacuum melting reduces the risk of rare-earth element oxidation and burn-off, while high-pressure gas powdering technology produces ultra-fine refining agent powder, improving the purification effect of the refining agent and thus enhancing the performance of the copper rods.

[0103] If conventional atmospheric smelting methods are used to prepare block-shaped rare earth refining agents, the rare earth elements are easily burned off to form oxides, which are not easily broken down and can only be added in large blocks, resulting in a very limited refining effect. Furthermore, rare earth oxides are difficult to dissolve in molten copper, suspending or floating on the surface, easily forming impurity points and crack initiation points, affecting the wire drawing performance of the copper rod. While adding excessive amounts of rare earth refining agents can further improve the performance of the copper rod, the improvement is limited, and the amount added needs to be carefully considered considering cost. Comparing the performance data of ratios 3, 4, and 5, it was found that gadolinium and holmium had the best purification effect, followed by praseodymium and neodymium, while lanthanum and cerium were the worst. This is determined by the activity and density of the rare earth elements; higher activity and density result in a more significant purification effect. However, in actual production, cost factors must be considered. Considering both overall cost and purification effect, a 1:1:1:1 ratio of praseodymium, neodymium, gadolinium, and holmium yields the best results.

[0104] By comparing Examples 1, 9, and 10, it was found that a smaller average particle size resulted in better purification and impurity removal. This is because a smaller average particle size leads to higher particle activity, more uniform dispersion, and a larger contact area with molten copper. However, compared to Example 1, the smaller average particle size in Comparative Example 9 had limited impact on improving the performance of the copper rod. A smaller average particle size resulted in a longer high-pressure gas powdering time, increased difficulty, and higher requirements for anti-oxidation measures, significantly increasing the production cost of powdering. Therefore, it is not advisable to choose an excessively small average particle size.

[0105] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method of producing a low-oxygen copper rod, characterized by, The method comprises the following steps: S1, mixing copper and rare earth metals according to the mass ratio of (52-64):(32-48), melting in a vacuum melting furnace, making alloy particles from the melted mixed metals, and using a high-pressure gas mill to make a refining agent powder; S2, adding the refining agent powder into copper water, cooling to make an ingot, and rolling to obtain low-oxygen copper rods; The rare earth metals include light rare earth and heavy rare earth; the powder of the refining agent has an average particle size ranging from 3 to 10 μm.

2. The method of claim 1, wherein, The light rare earth includes praseodymium and neodymium, and the heavy rare earth includes gadolinium and holmium.

3. The method of claim 2, wherein, The rare earth metals are praseodymium, neodymium, gadolinium and holmium.

4. The method of claim 3, wherein, The mass ratio of praseodymium, neodymium, gadolinium and holmium is (8-12):(8-12):(8-12):(8-12).

5. The method of claim 1, wherein, In step S1, the melting conditions are as follows: the melting temperature is 1250-1350 ℃, the preheating vacuum degree is 8-10 pa, the melting vacuum degree is 800-1000 pa, and the melting time is 3-5 h.

6. The method of claim 1, wherein, In step S1, the alloy particles are prepared by a rotating water-cooled disc, and the particle size of the alloy particles is less than 1 mm.

7. The method of claim 1, wherein, In step S1, the high-pressure gas mill has the following conditions for preparing the refining agent powder: the working medium pressure is 1.0-1.5 Mpa, and the mill chamber pressure is 0.08-0.15 Mpa; and the average particle size of the prepared refining agent powder is 5-10 μm.

8. The method of claim 1, wherein, In step S2, the method for adding the refining agent powder into copper water is as follows: using high-pressure high-purity nitrogen to uniformly spray the refining agent powder into copper water, the nitrogen pressure is 2-4 Mpa, and the nitrogen purity is ≥99.99%.

9. The method of claim 1, wherein, In step S2, the adding amount of the refining agent powder is m=(0.08-0.12)*M*n, and the unit is kg, wherein M is the copper water flow (T / h), and n is the oxygen content in the copper water (ppm).

10. A refining agent for producing a low-oxygen copper rod, characterized by, The components of the refining agent include copper, praseodymium, neodymium, gadolinium and holmium, and the mass ratio of each component is (52-64):(8-12):(8-12):(8-12):(8-12); and the average particle size of the refining agent is 3-10 μm.

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