A method for preparing oxygen-free copper

Abstract

The invention discloses a method for preparing oxygen-free copper, comprising: vacuum melting and removing impurities from a copper raw material to obtain a desired copper liquid, transferring the copper raw material into a refining furnace in a non-vacuum state through a sealed flow channel, the refining furnace comprising a heat-insulating refining chamber with a first cavity formed therein, and a buffer chamber to be cast with a second cavity sealed and connected to the first cavity formed therein, refining and removing impurities from the desired copper liquid in the heat-insulating refining chamber to obtain a refined copper liquid contained in the first cavity, causing the refined copper liquid to flow out of the first cavity and flow upward under the action of a first external force, and then flow into the second cavity; when the first external force is weakened or removed, the refined copper liquid stops flowing into the second cavity; causing the refined copper liquid entering the second cavity to flow downward and enter a cold zone in a crystallizer in an up-down direction for crystallization, and drawing out oxygen-free copper in an up-down direction; the method of the invention can not only realize the preparation of high-purity and large-sized oxygen-free copper, but also realize continuous or intermittent casting, with low energy consumption and high efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of copper processing, and in particular to a method for preparing oxygen-free copper. Background Art

[0002] Oxygen-free copper (Oxygen-free copper) is theoretically pure copper free of oxygen and any deoxidizer residues. However, it does contain trace amounts of oxygen and other impurities. Oxygen-free copper is virtually free of hydrogen embrittlement, exhibits high electrical conductivity, and exhibits excellent machinability, weldability, corrosion resistance, and low-temperature performance. It is widely used in electronics, communications, and other fields.

[0003] At present, it is generally believed that oxygen-free copper is divided into ordinary oxygen-free copper and high-purity oxygen-free copper. Ordinary oxygen-free copper can be smelted in an industrial frequency iron-core induction furnace, while the smelting of high-purity oxygen-free copper should adopt a vacuum smelting process. The vacuum smelting process mainly causes the smelting furnace and refining and pouring system to be enclosed in the same vacuum chamber. That is, the entire process is carried out under a vacuum state, which can reduce the interference of external factors in the processing process and thus facilitate the production of high-purity oxygen-free copper with a low total impurity content. However, despite the above advantages, this process is difficult to achieve continuous production and can only be carried out in batches, resulting in low production efficiency. Moreover, since all operations can only be carried out within the limited space of the vacuum chamber, the volume of the induction furnace is inevitably limited. It is only suitable for the production of small-sized or small-batch ingots, but not for the production of larger-sized ingots, such as those required for plate, strip and tubular products. In addition, since all processes are carried out in the same vacuum chamber, the vacuum chamber requires a large area, and the vacuum system of the equipment used must meet high standards and high processing capabilities, resulting in complex equipment, high cost, and very high operating and maintenance costs. Restricted by these factors, the vacuum melting process is mostly used in university laboratories or research institutes for scientific research, and is rarely used in large-scale production enterprises.

[0004] In response to the above problems, the prior art discloses a horizontal continuous casting process for large-diameter high-purity oxygen-free copper ingots and a connected furnace thereof, wherein the connected furnace comprises a smelting furnace, a heat-insulating refining furnace and a crystallizer, the bottom of the smelting furnace is connected to the bottom of the heat-insulating refining furnace by a pipeline, the crystallizer is connected to the horizontal direction of the melt outlet of the heat-insulating refining furnace, a water cooling system is arranged on the crystallizer, the smelting furnace and the heat-insulating furnace are both provided with a calcined carbon layer, a first argon gas pipeline is provided at the bottom of the smelting furnace, a second argon gas pipeline is provided at the bottom of the heat-insulating furnace, and two opposing electromagnetic stirrers are installed on the outer wall of the smelting furnace; this process makes the smelting furnace and the heat-insulating refining furnace at the same temperature and constant temperature smelting, and makes the smelting furnace and the heat-insulating refining furnace always in a sealed connection and communication, although it ensures that the copper liquid does not come into contact with the outside air during the smelting and impurity removal process and secondary impurity doping occurs, but the connected furnace has at least the following disadvantages: First, the smelting furnace and the holding refining furnace are always in a sealed connection, which means that the copper liquid does not stay in the system for a long time, resulting in poor impurity removal effect. Second, the smelting furnace and the holding refining furnace use the same temperature, which means that the temperature cannot be too low (1180-1230°C is actually used in this solution), otherwise it cannot achieve good smelting, resulting in high energy consumption. Third, the structure of this solution can only be cast horizontally. The influence of gravity during the casting process of oxygen-free copper will increase the difference in the microstructure in the radial direction. Especially when preparing oxygen-free copper with large radial dimensions, the influence of gravity will more significantly cause inconsistency in the microstructure, which has a negative impact on product performance. Fourth, during horizontal casting, the cooling water sprayed onto the oxygen-free copper extending in the horizontal direction can only contact the oxygen-free copper for a short time, resulting in poor cooling effect, requiring a large amount of cooling water, and causing a large waste of water resources. Summary of the Invention

[0005] The object of the present invention is to overcome one or more deficiencies in the prior art and to provide an improved process for preparing oxygen-free copper.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing oxygen-free copper, the preparation method comprising:

[0007] The copper raw material is vacuum-melted in a smelting furnace in a vacuum melting chamber to remove impurities, and is melted to a desired state to obtain the desired copper liquid;

[0008] The expected copper liquid is transferred into a refining furnace located outside the vacuum melting chamber through a sealed launder, the refining furnace comprising a heat-insulating refining chamber having a first cavity and a buffer chamber to be cast having a second cavity, the expected copper liquid is refined and impurities removed in the heat-insulating refining chamber to obtain refined copper liquid contained in the first cavity, the first cavity and the second cavity being in sealed communication with each other;

[0009] The refined copper liquid is caused to flow out of the first cavity and upward under the action of a first external force, and then flow into the second cavity; when the first external force is weakened or removed, the refined copper liquid stops flowing into the second cavity;

[0010] The refined copper liquid entering the second chamber flows downward under the action of a second external force and enters the cold zone in the crystallizer in the vertical direction for crystallization, and oxygen-free copper is pulled out in the vertical direction, wherein the second external force includes gravity.

[0011] According to some preferred aspects of the present invention, during the casting process, the amount of the refined copper liquid flowing into the buffer chamber to be cast is controlled by adjusting the magnitude of the first external force, thereby controlling the amount of the refined copper liquid in the buffer chamber to be cast to maintain a change of -3 wt.% to 3 wt.%. In some embodiments of the present invention, during the casting process, the amount of the refined copper liquid flowing into the buffer chamber to be cast is controlled by adjusting the magnitude of the first external force, thereby controlling the amount of the refined copper liquid in the buffer chamber to be cast to maintain a change of -2 wt.% to 2 wt.%. In some embodiments of the present invention, during the casting process, the amount of the refined copper liquid flowing into the buffer chamber to be cast is controlled by adjusting the magnitude of the first external force, thereby controlling the amount of the refined copper liquid in the buffer chamber to be cast to maintain a change of -1 wt.% to 1 wt.%. In some embodiments of the present invention, during the casting process, the amount of the refined copper liquid flowing into the buffer chamber to be cast is controlled by adjusting the magnitude of the first external force, thereby controlling the amount of the refined copper liquid in the buffer chamber to be cast to maintain a change of -0.5 wt.% to 0.5 wt.%.

[0012] Furthermore, the amount of the refined copper liquid in the buffer chamber to be cast is controlled to remain constant, so that the refined copper liquid is cast under isobaric conditions.

[0013] According to some preferred aspects of the present invention, the first external force is controlled to act on the upper surface of the refined copper liquid and causes the refined copper liquid to separate from the first cavity from the lower part of the heat-insulating refining chamber.

[0014] According to some preferred and specific aspects of the present invention, the first external force is gas pressure, which is generated by introducing gas into the upper space of the first cavity.

[0015] According to some preferred aspects of the present invention, the gas is preferably a gas that does not react with copper to avoid the introduction of new impurities or the generation of new impurities. The gas includes but is not limited to nitrogen and / or argon.

[0016] According to some preferred and specific aspects of the present invention, the refined copper liquid flows out from the lower part of the first cavity under the action of a first external force and flows obliquely upward, and then flows into the interior of the second cavity from the upper part or middle part.

[0017] According to a specific aspect of the present invention, the second external force is gravity.

[0018] According to some preferred aspects of the present invention, the center line of the second cavity and the center line of the crystallizer coincide with each other.

[0019] Furthermore, the center line of the second cavity and the center line of the crystallizer extend in the vertical direction respectively.

[0020] According to some preferred aspects of the present invention, the operating temperature of the smelting furnace is greater than the operating temperature of the refining furnace.

[0021] Furthermore, the operating temperature of the smelting furnace is 1180-1250°C, and the operating temperature of the refining furnace is 1100-1180°C.

[0022] According to some preferred aspects of the present invention, the vacuum degree of the vacuum melting chamber is 1×10 -2 ~20×10 -2 Pa.

[0023] According to some preferred and specific aspects of the present invention, the smelting furnace is a coreless induction furnace, and the heat-insulating refining chamber is an iron-core induction furnace.

[0024] According to some preferred aspects of the present invention, the surfaces of the molten copper contained in the heat-insulating refining chamber and the buffer chamber to be cast are covered with a covering that can isolate the air and / or react with the impurities.

[0025] Furthermore, the covering is charcoal and / or flaky graphite.

[0026] According to some preferred aspects of the present invention, a refractory layer is provided at the bottom of the heat-insulating refining chamber, and perforated blowing bricks are pre-embedded in the refractory layer, and the copper liquid is refined by blowing in reactive gas that can react with at least part of the impurities.

[0027] Furthermore, the reactive gas is carbon monoxide or a mixture of carbon monoxide and an inert gas.

[0028] According to some preferred aspects of the present invention, the sealed flow channel includes a conducting state and a blocked state. When the copper raw material is vacuum-smelted in the smelting furnace of the vacuum smelting chamber, the sealed flow channel is in the blocked state. When the expected copper liquid needs to be transferred to the refining furnace, the sealed flow channel is in the conducting state and is connected to the refining furnace.

[0029] According to the present invention, the preparation method includes a continuous casting state and an intermittent casting state.

[0030] Furthermore, when the preparation method is in a continuous casting state, according to the amount of the refined copper liquid required for casting per unit time, the number of the smelting furnaces and / or the amount of vacuum smelting in each batch are controlled so that the insulation refining chamber has the amount required for casting of the buffer chamber to be cast, thereby achieving continuous casting.

[0031] Furthermore, when the preparation method is in an intermittent casting state, the application or withdrawal of the first external force is controlled to control the amount of the refined copper liquid entering the second cavity to achieve the required amount for a single batch of casting; or, the amount of the refined copper liquid contained in the heat-insulating refining chamber at a single time is the required amount for a single batch of casting.

[0032] According to some preferred aspects of the present invention, the preparation method adopts an oxygen-free copper production system to prepare oxygen-free copper, and the oxygen-free copper production system comprises:

[0033] Vacuum melting equipment and oxygen-free copper casting equipment for vacuum melting of copper raw materials;

[0034] The vacuum melting device includes a vacuum melting chamber, a melting furnace arranged in the vacuum melting chamber, and a vacuum pumping mechanism connected to the vacuum melting chamber. The vacuum melting chamber is provided with a feeding portion for adding copper raw materials into the melting furnace and a sealed launder.

[0035] The oxygen-free copper casting device includes a refining furnace and a crystallizer. The refining furnace includes an insulation refining chamber and a buffer chamber to be cast. The insulation refining chamber includes a heating mechanism for maintaining the internal temperature, a first cavity capable of communicating with the sealed flow channel, a refined copper liquid output pipe, and a gas conveying mechanism connected to the upper part of the first cavity and used to convey gas into the first cavity. The buffer chamber to be cast includes a second cavity extending in the up-down direction and a refined copper liquid input pipe connected to the upper part or middle part of the second cavity. The inlet of the refined copper liquid output pipe is connected to the first cavity, the outlet of the refined copper liquid output pipe is connected to the refined copper liquid input pipe, and the height of the inlet of the refined copper liquid output pipe in the vertical direction is less than the height of the outlet of the refined copper liquid output pipe in the vertical direction. The crystallizer includes an oxygen-free copper output channel, the oxygen-free copper output channel is connected to the bottom of the second cavity, and the oxygen-free copper output channel extends in the up-down direction.

[0036] In some embodiments of the present invention, the crystallizer is a graphite crystallizer.

[0037] According to some preferred aspects of the present invention, the heat-insulating refining chamber further includes a receiving chamber formed with a receiving channel, the first cavity is connected to the sealed flow groove through the receiving channel, the height of the inlet of the receiving channel in the vertical direction is greater than the height of any point of the refined copper liquid input pipe in the vertical direction, and the receiving channel passes through the heating mechanism.

[0038] According to some preferred aspects of the present invention, the refining furnace further comprises a docking flow channel detachably connected to the sealing flow channel, the docking flow channel being provided on the material receiving chamber and being in communication with the material receiving channel;

[0039] The vacuum melting device further includes a blocking mechanism for blocking the sealed flow channel. When the copper raw material is vacuum-smelted in the melting furnace of the vacuum melting chamber, the sealed flow channel is separated from the docking flow channel, and the blocking mechanism blocks the sealed flow channel.

[0040] When the expected copper liquid needs to be transferred into the refining furnace, the blocking mechanism is removed and the sealing flow channel is connected to the docking flow channel.

[0041] According to some preferred aspects of the present invention, the refined copper liquid output pipe includes a first sub-output pipe extending in the up-down direction and a second sub-output pipe connected to the first sub-output pipe and extending in the horizontal direction, the first sub-output pipe is connected to the lower end of the first cavity, and the second sub-output pipe is connected to the refined copper liquid input pipe.

[0042] According to some preferred aspects of the present invention, the acute angle between the extension direction of the first sub-output tube and the horizontal direction is 15°-80°; further, the acute angle between the extension direction of the first sub-output tube and the horizontal direction is 20°-70°.

[0043] According to some preferred and specific aspects of the present invention, the refined copper liquid inlet pipe extends in a horizontal direction.

[0044] According to some preferred aspects of the present invention, the second chamber includes an upper sub-chamber and a lower sub-chamber integrally formed with the upper sub-chamber, the width of the upper sub-chamber at all positions in its extension direction is the same, the width of the lower sub-chamber at all positions in its extension direction is the same, and the width of the upper sub-chamber is greater than the width of the lower sub-chamber, the refined copper liquid inlet pipe is connected to the upper sub-chamber, and the bottom of the lower sub-chamber is provided with a refined copper liquid outlet connected to the oxygen-free copper output channel.

[0045] According to some preferred aspects of the present invention, the heat-insulating refining chamber is detachably connected to the buffer chamber to be cast. When the heat-insulating refining chamber is connected to the buffer chamber to be cast, the refined copper liquid inlet pipe is connected to the refined copper liquid output pipe; when the heat-insulating refining chamber is separated from the buffer chamber to be cast, the refined copper liquid inlet pipe is separated from the refined copper liquid output pipe.

[0046] According to some preferred aspects of the present invention, the crystallizer is detachably arranged on the buffer chamber to be cast. When the crystallizer is arranged on the buffer chamber to be cast, the center line of the oxygen-free copper output channel coincides with the center line of the second cavity.

[0047] According to some specific aspects of the present invention, the oxygen-free copper production system includes a first state and a second state, and the vacuum melting device includes a melting state and a non-melting state;

[0048] When the oxygen-free copper production system is in the first state, the vacuum melting device is in a non-melting state, and the vacuum melting device is connected or disconnected with the heat-insulating refining chamber;

[0049] When the oxygen-free copper production system is in the second state, the vacuum melting device is in a melting state, and the vacuum melting device is not connected to the heat-insulating refining chamber.

[0050] According to some preferred and specific aspects of the present invention, the smelting furnace is rotatably disposed in the vacuum smelting chamber, and the vacuum smelting device further comprises a tilting mechanism for tilting the smelting furnace, and a transfer chute located in the vacuum smelting chamber and connected to the sealed chute;

[0051] The smelting furnace includes a smelting state and a tilting state. When the smelting furnace is in the smelting state, the smelting furnace and the sealed flow channel are independent of each other, and the opening of the smelting furnace faces upward;

[0052] When the smelting furnace is in a tilted state, the opening of the smelting furnace is located above the transfer chute and tilted toward the transfer chute;

[0053] The tilting mechanism is a first hydraulic cylinder, which includes a first cylinder body rotatably arranged in the vacuum melting chamber, a first hydraulic rod slidably arranged on the first cylinder body and extending in the up-down direction, and a first hydraulic system for driving the first hydraulic rod to perform reciprocating linear motion. The upper end of the first hydraulic rod is connected to the melting furnace, and the rotation axis of the melting furnace and the rotation axis of the first cylinder body extend in the front-to-back direction respectively and are parallel to each other.

[0054] According to some preferred and specific aspects of the present invention, the smelting furnace includes a furnace body and a guide tube rotatably disposed in the vacuum smelting chamber, and the vacuum smelting device further includes a tilting assembly for tilting the furnace body;

[0055] The conduit includes a first sub-conduit and a second sub-conduit connected to one end of the first sub-conduit, the other end of the first sub-conduit is connected to the furnace body, and one end of the second sub-conduit is connected to the sealed flow groove. The conduit can rotate relative to the sealed flow groove, and the rotation axis of the conduit coincides with the rotation axis of the furnace body.

[0056] The smelting furnace includes a smelting state and a tilting state. When the smelting furnace is in the smelting state, the first sub-conduit extends in an up-down direction, and a height of one end of the first sub-conduit connected to the second sub-conduit in a vertical direction is greater than a height of the other end of the first sub-conduit connected to the furnace body.

[0057] When the smelting furnace is in a tilted state, the vertical height of one end of the first sub-conduit connected to the second sub-conduit is less than or equal to the height of the other end of the first sub-conduit connected to the furnace body;

[0058] The height of one end of the second sub-conduit communicating with the sealing flow groove in the vertical direction is less than or equal to the height of the other end of the second sub-conduit communicating with the first sub-conduit;

[0059] The tilting assembly is a second hydraulic cylinder, which includes a second cylinder body rotatably arranged in the vacuum melting chamber, a second hydraulic rod slidably arranged on the second cylinder body and extending in the up-down direction, and a second hydraulic system for driving the second hydraulic rod to perform reciprocating linear motion. The upper end of the second hydraulic rod is connected to the melting furnace, and the rotation axis of the melting furnace and the rotation axis of the second cylinder body extend in the left-right direction respectively and are parallel to each other.

[0060] In the present invention, all parts of the equipment, unless they need to have inlets and outlets, preferably have excellent sealing properties, which helps to prevent air or other impurities from entering and causing contamination to the circulating fluid, such as copper liquid.

[0061] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0062] After a large number of analytical experimental studies, the inventors found that in the preparation process of oxygen-free copper, only the copper raw material smelting process in the initial stage of processing can be vacuum smelted to maximize the removal of impurities, and then combined with the refining process outside the vacuum smelting chamber (non-vacuum), not only can extremely high-purity oxygen-free copper be produced, but also the space occupation of the vacuum smelting chamber is greatly reduced, the requirements for vacuum equipment are reduced, and energy consumption is greatly reduced. Under the same space conditions, more high-purity copper liquid can be smelted in a single time; further, on the basis of the above, the present invention first performs vacuum smelting and smelts it to the expected state, and then transfers it to the refining process outside the vacuum smelting chamber (non-vacuum). Moreover, the present invention innovatively makes the refined copper liquid obtained by heat preservation and refining need to overcome gravity and other factors under the action of external force before it can be transferred to the cache in the buffer chamber to be cast, that is, it is difficult for the refined copper liquid to flow freely from the heat preservation and refining chamber to the buffer chamber to be cast. On the one hand, the presence or size of the external force can be controlled to thereby The amount of refined copper liquid entering the buffer chamber to be cast is controlled, thereby realizing both continuous casting and intermittent casting; on the other hand, the existence of the buffer chamber enables the copper liquid to be cast to be in a relatively stable state, avoiding negative impact on the organizational structure of the cast oxygen-free copper, and at the same time, due to the method of realizing the transfer of refined copper liquid by means of external force, the heat-insulating refining chamber of the present invention and the buffer chamber to be cast can be sealed and connected, thereby, firstly, avoiding the introduction of new impurities in the casting process, secondly, there is no need to set an opening and closing mechanism to cut off the flow of high-temperature copper liquid, reducing the difficulty of equipment manufacturing, and thirdly, the present invention can set the crystallizer below the buffer chamber to be cast so that the refined copper liquid can flow out downward and enter the cold zone in the crystallizer in the up and down directions for crystallization, realizing the pulling out of oxygen-free copper in the up and down directions, thereby avoiding the defects of poor cooling effect and large differences in the organizational structure of oxygen-free copper in the radial direction during horizontal casting, and large-size high-purity oxygen-free copper can be prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0064] Figure 1 Schematic diagram of the process for preparing oxygen-free copper according to an embodiment of the present invention;

[0065] Figure 2 Schematic diagram of the structure of the refining furnace in an embodiment of the present invention;

[0066] Figure 3 This is a structural diagram of a refining furnace in an embodiment of the present invention with some structures omitted;

[0067] Figure 4 A schematic diagram of a partial structure of a heat preservation and scouring chamber in an embodiment of the present invention;

[0068] Figure 5 This is a partial structural diagram of the buffer chamber to be cast in an embodiment of the present invention;

[0069] Figure 6 Schematic diagram of the structure of an oxygen-free copper casting device in an embodiment of the present invention;

[0070] Figure 7 This is one of the structural schematic diagrams of implementation mode 1 of the oxygen-free copper production system in an embodiment of the present invention;

[0071] Figure 8 This is a second structural diagram of implementation mode 1 of the oxygen-free copper production system in an embodiment of the present invention;

[0072] Figure 9 for Figure 8 A magnified schematic diagram of point A in the middle;

[0073] Figure 10 This is a third structural diagram of implementation mode 1 of the oxygen-free copper production system in an embodiment of the present invention;

[0074] Figure 11 This is one of the structural schematic diagrams of embodiment 2 of the oxygen-free copper production system in an embodiment of the present invention;

[0075] Figure 12 This is a second structural diagram of implementation mode 2 of the oxygen-free copper production system in an embodiment of the present invention;

[0076] Figure 13 This is a third structural diagram of implementation mode 2 of the oxygen-free copper production system in an embodiment of the present invention;

[0077] Among them, 1. Refining furnace; 11. Insulation refining chamber; 111. Heating mechanism; 112. First cavity; 113. Refined copper liquid output pipe; 1131. First sub-output pipe; 1132. Second sub-output pipe; 114. Receiving chamber; 1141. Receiving channel; 11411. First receiving sub-channel; 11412. Second receiving sub-channel; 115. Docking chute; 12. Buffer chamber to be cast; 121. Second cavity; 1211. Upper sub-chamber; 1212. Lower sub-chamber; 122. Refined copper liquid input pipe; 2. Oxygen-free copper casting device; 21. Crystallizer; 3. Oxygen-free copper production Production system; 31. Vacuum melting device; 311. Vacuum melting chamber; 312. First melting furnace; 313. Vacuum pumping mechanism; 314. Sealing chute; 315. Transfer chute; 316. First hydraulic cylinder; 3161. First cylinder body; 3162. First hydraulic rod; 317. Second melting furnace; 3171. Furnace body; 3172. Conduit; 31721. First sub-conduit; 31722. Second sub-conduit; 318. Blocking mechanism; 3181. Sealing gland; 3182. Flexible graphite sealing ring; 319. Feeding section; 4. Cover; 5. Refined copper liquid; 6. Copper raw material. DETAILED DESCRIPTION

[0078] The main concept of the present invention is to combine and optimize vacuum smelting technology and non-vacuum smelting technology. In the vacuum chamber, only equipment for vacuum smelting of copper raw materials is set up, and equipment for refining and condensation casting is not set up, which greatly reduces the space of the vacuum chamber, resulting in a compact structure of the vacuum equipment and a simplified system, thereby achieving the effect of reducing investment cost and operating cost. In addition, the vacuum effect is better when the vacuum chamber is used for smelting, and oxygen, hydrogen and other volatile impurities can be more effectively removed during the copper molten smelting process; non-vacuum state is adopted for heat preservation (refining) and casting, and at this time, the high-purity copper liquid obtained in the early stage is maintained or further refined. In particular, the present invention uses external force to intervene in the circulation of the refined copper liquid obtained by heat preservation and refining under the non-vacuum state, so that the refined copper liquid can be reflected in the amount of circulation when the external force changes, thereby making the amount of refined copper liquid to be cast in the buffer chamber to be cast connected to the crystallizer effectively and timely regulated, thereby both Both continuous casting and intermittent casting can be achieved, and since the power for supplying refined copper liquid is only the action of external forces that need to overcome factors such as gravity, there is no need to use an opening and closing mechanism to open and close the channel between the buffer chamber to be cast and the heat-insulating refining chamber, which reduces the difficulty of equipment manufacturing, and the heat-insulating refining chamber and the buffer chamber to be cast can be sealed and connected, avoiding the introduction of new impurities during the casting process, and allowing the copper liquid to be cast to be in a relatively stable state, avoiding negative impacts on the microstructure of the cast oxygen-free copper. In addition, by controlling the supply of refined copper liquid with the help of external force, the present invention can also set the crystallizer below the buffer chamber to be cast so that the refined copper liquid can flow out downward and enter the cold zone in the crystallizer in the up and down directions for crystallization, realizing the pulling out of oxygen-free copper in the up and down directions, thereby avoiding the defects of poor cooling effect and large differences in the microstructure of oxygen-free copper in the radial direction during horizontal casting, and large-size high-purity oxygen-free copper can be prepared.

[0079] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0080] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0081] Please refer to Figure 1As shown, it exemplarily gives a preparation process of oxygen-free copper, first providing a copper raw material, then vacuum smelting and until the expected state, obtaining the expected copper liquid, and transferring the expected copper liquid into the heat-insulating refining chamber outside the vacuum smelting chamber through a sealed launder for refining and impurity removal to obtain the refined copper liquid contained in the first cavity, so that the refined copper liquid flows out of the first cavity and flows upward under the action of a first external force, and then flows into the second cavity; when the first external force is weakened or removed, the refined copper liquid stops flowing into the second cavity; the refined copper liquid entering the second cavity is caused to flow downward under the action of a second external force and enter the cold zone in the crystallizer in the up and down directions for crystallization, and the oxygen-free copper is pulled out in the up and down directions.

[0082] The following combination Figures 2 to 13 The oxygen-free copper production system shown further introduces the above-mentioned preparation method of oxygen-free copper, which is more conducive to understanding the operation process and specific implementation methods of this preparation method.

[0083] Please refer to Figures 2 to 13 The above-mentioned method for preparing oxygen-free copper adopts the following oxygen-free copper production system 3 to prepare oxygen-free copper. The oxygen-free copper production system 3 includes: a vacuum melting device 31 for vacuum melting copper raw material 6, and an oxygen-free copper casting device 2.

[0084] The vacuum melting device 31 includes a vacuum melting chamber 311, a melting furnace disposed in the vacuum melting chamber 311, and a vacuum pumping mechanism 313 connected to the vacuum melting chamber 311. The vacuum melting chamber 311 is provided with a feeding portion 319 for feeding the copper raw material 6 into the melting furnace and a sealed flow channel 314.

[0085] The oxygen-free copper casting device 2 includes a refining furnace 1 and a crystallizer 21. The refining furnace 1 includes a heat-insulating refining chamber 11 and a buffer chamber to be cast 12. The heat-insulating refining chamber 11 includes a heating mechanism 111 for maintaining the internal temperature, a first cavity 112 capable of communicating with a sealed flow channel 314, a refined copper liquid output pipe 113, and a gas delivery mechanism (not shown) connected to the upper part of the first cavity 112 and used for delivering gas to the first cavity 112. The buffer chamber to be cast 12 includes a second cavity 121 extending in the up-down direction and a second cavity 122 connected to the first cavity 112. The upper or middle part of the second cavity 121 is connected to the refined copper liquid input pipe 122, the inlet of the refined copper liquid output pipe 113 is connected to the first cavity 112, the outlet of the refined copper liquid output pipe 113 is connected to the refined copper liquid input pipe 122, and the height of the inlet of the refined copper liquid output pipe 113 in the vertical direction is less than the height of the outlet of the refined copper liquid output pipe 113 in the vertical direction. The crystallizer 21 includes an oxygen-free copper output channel, which is connected to the bottom of the second cavity 121 and extends in the up and down direction.

[0086] In this example, the heat-insulating refining chamber 11 also includes a receiving chamber 114 having a receiving channel 1141, and the refining furnace 1 also includes a docking flow channel 115 that can be detachably connected to the sealed flow channel 314, and the docking flow channel 115 is arranged on the receiving chamber 114 and is connected to the receiving channel 1141; the first volume 112 is connected to the sealed flow channel 314 through the receiving channel 1141, and the height of the inlet of the receiving channel 1141 in the vertical direction is greater than the height of any point of the refined copper liquid inlet pipe 122 in the vertical direction (which is conducive to the refined copper liquid 5 to more easily enter the second volume 121 from the refined copper liquid inlet pipe 122 when gas pressure acts), and the receiving channel 1141 passes through the heating mechanism 111.

[0087] like Figure 2 As shown, from left to right, there are provided a docking flow channel 115, a receiving channel 1141, a first cavity 112 and a second cavity 121 that are interconnected. Figure 3 The specific communication state of the receiving channel 1141, the first cavity 112 and the second cavity 121 can be seen; Figure 4-5 The figure shows a schematic diagram of the heat preservation and refining chamber 11 and the buffer chamber 12 for casting that can be detachably connected and separated; Figure 6 The overall structural diagram of the oxygen-free copper casting device 2 of this example is further provided.

[0088] Furthermore, when the heat-insulating refining chamber 11 is connected to the buffer chamber to be cast 12, the refined copper liquid inlet pipe 122 is connected to the refined copper liquid outlet pipe 113; when the heat-insulating refining chamber 11 is separated from the buffer chamber to be cast 12, the refined copper liquid inlet pipe 122 is separated from the refined copper liquid outlet pipe 113.

[0089] Further, if Figure 2-Figure 4 As shown, the refined copper liquid output pipe 113 includes a first sub-output pipe 1131 extending in the up-down direction, and a second sub-output pipe 1132 connected to the first sub-output pipe 1131 and extending in the horizontal direction. The first sub-output pipe 1131 is connected to the lower end of the first cavity 112, and the second sub-output pipe 1132 is connected to the refined copper liquid input pipe 122. The acute angle between the extension direction of the first sub-output pipe 1131 and the horizontal direction is 15°-80°, or can be 20°-70°, for example, it can be 20°, 30°, 40°, 50°, 60°, 70°, etc. The refined copper liquid input pipe 122 extends in the horizontal direction.

[0090] At the same time, if Figure 3As shown, the second chamber 121 includes an upper sub-chamber 1211 and a lower sub-chamber 1212 integrally formed with the upper sub-chamber 1211. The width of the upper sub-chamber 1211 at each position in its extension direction is the same, and the width of the lower sub-chamber 1212 at each position in its extension direction is the same, and the width of the upper sub-chamber 1211 is greater than the width of the lower sub-chamber 1212. The refined copper liquid inlet pipe 122 is connected to the upper sub-chamber 1211, and the bottom of the lower sub-chamber 1212 is provided with a refined copper liquid outlet connected to the oxygen-free copper output channel, which is conducive to casting in the upper and lower directions.

[0091] like Figure 6 As shown, the crystallizer 21 can be set on the buffer chamber to be cast 12 and the two can be connected in a detachable manner. When the crystallizer 21 is set on the buffer chamber to be cast 12, the center line of the oxygen-free copper output channel coincides with the center line of the second cavity 121, further ensuring casting in the up and down directions and improving the casting quality. The crystallizer 21 can be a graphite crystallizer.

[0092] In this example, the oxygen-free copper production system 3 includes a first state and a second state, and the vacuum melting device 31 includes a melting state and a non-melting state;

[0093] When the oxygen-free copper production system 3 is in the first state, the vacuum melting device 31 is in a non-melting state, and the vacuum melting device 31 is connected or disconnected with the heat-insulating refining chamber 11;

[0094] When the oxygen-free copper production system 3 is in the second state, the vacuum melting device 31 is in a melting state, and the vacuum melting device 31 is not connected to the heat preservation and refining chamber 11, which can prevent the vacuum melting process from being disturbed by the heat preservation and refining equipment in a non-vacuum state.

[0095] Furthermore, the smelting furnace in this example includes at least two embodiments. The first embodiment of the smelting furnace (embodiment 1) can be referred to Figure 7-10 The smelting furnace (hereinafter referred to as the first smelting furnace 312) is rotatably disposed in the vacuum smelting chamber 311. The vacuum smelting device 31 further includes a tilting mechanism for tilting the first smelting furnace 312, and a transfer chute 315 located in the vacuum smelting chamber 311 and connected to the sealed chute 314.

[0096] The first smelting furnace 312 includes a smelting state and a tilting state. When the first smelting furnace 312 is in the smelting state, the first smelting furnace 312 and the sealing flow channel 314 are independent of each other, and the opening of the first smelting furnace 312 faces upward. Figure 8 As shown;

[0097] When the first smelting furnace 312 is in the tilted state, the opening of the first smelting furnace 312 is located above the transfer chute 315 and tilted toward the transfer chute 315. Figure 10 As shown, it exemplarily shows the position and shape of the first smelting furnace 312 when it is in a tilted state;

[0098] The tilting mechanism is a first hydraulic cylinder 316, which includes a first cylinder body 3161 rotatably disposed in the vacuum melting chamber 311, a first hydraulic rod 3162 slidably disposed on the first cylinder body 3161 and extending in the up-down direction, and a first hydraulic system (not shown; the working principle of the first hydraulic cylinder is well known in the art) for driving the first hydraulic rod 3162 to perform reciprocating linear motion. The upper end of the first hydraulic rod 3162 is connected to the first melting furnace 312, and the rotation axis of the first melting furnace 312 and the rotation axis of the first cylinder body 3161 extend in the front-to-back direction and are parallel to each other. The front-to-back direction here refers to the positional relationship when facing the accompanying drawings, and there will be changes if the direction facing the accompanying drawings is different.

[0099] The vacuum melting device 31 also includes a sealing mechanism 318 for sealing the sealing flow channel 314. When the copper raw material 6 is vacuum melted in the first melting furnace 312 of the vacuum melting chamber 311, the sealing flow channel 314 is separated from the docking flow channel 115, and the sealing mechanism 318 is sealed on the sealing flow channel 314. At this time, the oxygen-free copper production system 3 is in the second state; when the expected copper liquid needs to be transferred to the refining furnace 1, the sealing mechanism 318 is removed, and the sealing flow channel 314 is connected to the docking flow channel 115, and the oxygen-free copper production system 3 is in the first state.

[0100] like Figure 9 As shown, the sealing mechanism 318 may include a sealing cover 3181 and a flexible graphite sealing ring 3182, which may be integrated into one body. When the sealing flow groove 314 needs to be sealed, it is sleeved on the sealing flow groove 314, mainly to isolate it from contact with external air and other impurities. When the vacuum melting chamber 311 is vacuumed, it can be more tightly sleeved on the sealing flow groove 314, can be pressed on the outer wall of the vacuum melting chamber 311, or can be fixed by other structures and disassembled when needed.

[0101] In this embodiment 1, the copper raw material 6 is fed into the first smelting furnace 312 inside the vacuum smelting chamber 311 from the feeding part 319 provided at the upper part of the vacuum smelting chamber. The first smelting furnace 312 is smelted at a high temperature at the working temperature and vacuumed during the smelting process. Impurities such as oxygen and hydrogen are smelted and volatilized and removed by the vacuum pumping mechanism 313. During the smelting process, samples can be taken irregularly or regularly to monitor the effect of vacuum smelting until the expected state is reached and the expected copper liquid of ideal purity is obtained. When the expected copper liquid needs to be transferred to the oxygen-free copper casting device 2, the blocking mechanism 318 is removed and the sealing flow channel 314 is connected to the docking flow channel 115 (forming a vacuum flow channel 315). Figure 7 Then, the first smelting furnace 312 is tilted by the tilting mechanism so that the discharge port is located above the transfer chute 315 and tilted toward the transfer chute 315, forming a Figure 10 In the tilting state shown, the material inside can flow into the transfer flow channel 315 and continue to flow into the sealing flow channel 314, and then flow into the docking flow channel 115 connected to the sealing flow channel 314, and then enter the heat preservation and refining chamber 11 for heat preservation and refining, and then enter the buffer chamber 12 to be cast, and finally enter the crystallizer 21 for casting.

[0102] Further, the second embodiment of the smelting furnace (embodiment 2) can refer to Figure 11-13 The smelting furnace (hereinafter referred to as the second smelting furnace 317 to avoid confusion with the smelting furnace in the first embodiment) includes a furnace body 3171 and a guide tube 3172 rotatably disposed in the vacuum smelting chamber 311. The vacuum smelting device 31 also includes a tilting assembly for tilting the furnace body 3171.

[0103] The conduit 3172 includes a first sub-conduit 31721 and a second sub-conduit 31722 connected to one end of the first sub-conduit 31721. The other end of the first sub-conduit 31721 is connected to the furnace body 3171, and one end of the second sub-conduit 31722 is connected to the sealed flow groove 314. The conduit 3172 can rotate relative to the sealed flow groove 314 (to ensure that the conduit 3172 can rotate with the furnace body 3171), and the rotation axis of the conduit 3172 coincides with the rotation axis of the furnace body 3171.

[0104] The second smelting furnace 317 has a smelting state and a tilting state. When the second smelting furnace 317 is in the smelting state, the first sub-conduit 31721 extends in the vertical direction, and the end of the first sub-conduit 31721 connected to the second sub-conduit 31722 is vertically higher than the other end of the first sub-conduit 31721 connected to the furnace body 3171. In this state, the molten copper can only be smelted at high temperature inside the furnace body 3171 and will not enter the conduit 3172.

[0105] When the second smelting furnace 317 is in the tilted state, the vertical height of the end of the first sub-conduit 31721 connected to the second sub-conduit 31722 is less than or equal to the height of the other end of the first sub-conduit 31721 connected to the furnace body 3171. In this state, molten copper can flow out of the furnace body 3171 into the conduit 3172 under the action of internal pressure and gravity, and then flow into the sealed flow channel 314.

[0106] The vertical height of one end of the second sub-conduit 31722 connected to the sealed flow channel 314 is less than or equal to the height of the other end of the second sub-conduit 31722 connected to the first sub-conduit 31721, which helps to ensure smooth circulation of the molten copper and better emptying of the molten copper.

[0107] The tilting assembly is a second hydraulic cylinder (its principle is the same as that of the first hydraulic cylinder 316, the only difference being the process and direction of driving the smelting furnace to tilt). The second hydraulic cylinder includes a second cylinder body rotatably arranged in the vacuum melting chamber 311, a second hydraulic rod slidably arranged on the second cylinder body and extending in the up and down directions, and a second hydraulic system for driving the second hydraulic rod to perform reciprocating linear motion. The upper end of the second hydraulic rod is connected to the furnace body 3171. The rotation axis of the second smelting furnace 317 and the rotation axis of the second cylinder body extend in the left and right directions and are parallel to each other. The left and right directions here are the positional relationship when facing the attached figure, and there will be changes if the direction facing the attached figure is different.

[0108] In this second embodiment, the outflow method of the expected copper liquid is different from that in the first embodiment. Specifically, when the expected copper liquid needs to be transferred out, the furnace body 3171 is tilted by the tilting assembly. Since the conduit 3172 is connected to the furnace body 3171, the conduit 3172 also rotates during the rotation and tilting of the furnace body 3171. When the height of the end of the first sub-conduit 31721 connected to the second sub-conduit 31722 in the vertical direction is less than or equal to the height of the other end of the first sub-conduit 31721 connected to the furnace body 3171, due to the height difference and the existence of the expected internal copper liquid pressure, the expected copper liquid can smoothly flow from the inside of the furnace body 3171 to the conduit 3172, and flow through the conduit 3172 to the sealed flow groove 314, and then flow into the docking flow groove 115 connected to the sealed flow groove 314, and then enter the heat preservation and refining chamber 11 for heat preservation and refining, and then enter the buffer chamber 12 to be cast, and finally enter the crystallizer 21 for casting.

[0109] From the above, it can be seen that the preparation process of oxygen-free copper in this example can mainly include:

[0110] The copper raw material 6 is vacuum-melted in the smelting furnace of the vacuum smelting chamber 311 to remove impurities, and is smelted to the expected state to obtain the expected copper liquid. In this example, the expected state can be the limit state of vacuum smelting or determined according to the sampling test results during the smelting process until the set requirements are met, mainly including the detection of the content of copper, oxygen, hydrogen, etc. In theory, the higher the copper content, the better, and the lower the content of impurities such as oxygen and hydrogen, the better. However, in practice, there may inevitably be trace amounts of impurities. In this example, the vacuum smelting chamber 311 is used to focus on the vacuum smelting of the copper raw material 6, so that oxygen, hydrogen and other volatile impurities can be better removed to obtain the expected copper liquid of the ideal expected purity, greatly reducing the space of the vacuum chamber, making the vacuum equipment structure compact and the system relatively simple, thereby achieving the effect of reducing investment costs and operating costs. The copper raw material 6 used can be a raw material commonly used in the preparation of oxygen-free copper in the field, generally also referred to as qualified raw material.

[0111] The desired copper liquid is transferred into the refining furnace 1 located outside the vacuum melting chamber 311 through the sealed launder 314, and the desired copper liquid is refined and impurities removed in the heat-insulating refining chamber 11 to obtain the refined copper liquid 5 contained in the first chamber 112. The first chamber 112 and the second chamber 121 are sealed and communicated with each other.

[0112] The refined copper liquid 5 is caused to flow out of the first chamber 112 and upward under the action of the first external force, and then flow into the second chamber 121; when the first external force is weakened or removed, the refined copper liquid 5 can stop flowing into the second chamber 121; further, the first external force can be controlled to act on the upper surface of the refined copper liquid 5 and the refined copper liquid 5 can be separated from the first chamber 112 from the lower part of the heat-insulating refining chamber 11. The first external force can be generated by a gas conveying mechanism (not shown), that is, the first external force can be gas pressure, which is formed by introducing gas into the upper space of the first chamber 112. The gas is preferably a gas that does not react with copper to avoid introducing new impurities or generating new impurities. The gas includes but is not limited to nitrogen and / or argon. Under the action of the gas pressure, the refined copper liquid 5 flows out from the lower part of the first cavity 112 and flows obliquely upward, and then flows into the interior of the second cavity 121 from the upper part or the middle part thereof. The flow from the upper part or the middle part of the second cavity 121 into the interior of the second cavity 121 can be selected so that the upper surface of the refined copper liquid in the second cavity 121 and the position of the flowing refined copper liquid are substantially flush during isostatic casting, and the outflow amount is controlled to be equal to the inflow amount. In this state, it is more conducive to maintaining the refined copper liquid 5 in the second cavity 121 in a relatively balanced and static state, thereby reducing interference with the microstructure of the cast oxygen-free copper.

[0113] The refined copper liquid 5 entering the second chamber 121 flows downward under the action of a second external force and enters the cold zone in the crystallizer 21 in the vertical direction for crystallization, thereby pulling out oxygen-free copper in the vertical direction. The second external force is gravity.

[0114] Among them, during the casting process, the magnitude of the first external force is adjusted to control the amount of refined copper liquid 5 flowing into the buffer chamber 12 to be cast, and then the change in the amount of refined copper liquid 5 in the buffer chamber 12 to be cast is controlled to be maintained at -3wt.%~3wt.%, or -2wt.%~2wt.%, or -1wt.%~1wt.%, or -0.5wt.%~0.5wt.%; further, in this example, the amount of refined copper liquid 5 in the buffer chamber 12 to be cast is controlled to be constant, so that the refined copper liquid 5 is cast under isobaric conditions. Keeping it constant is more conducive to making the pressure conditions equal during the casting of the refined copper liquid, and obtaining an oxygen-free copper product with a relatively more uniform organizational structure.

[0115] In this example, the center line of the second cavity 121 and the center line of the crystallizer 21 coincide with each other, which is more conducive to the realization of the casting process in the up and down directions. Furthermore, the center line of the second cavity 121 and the center line of the crystallizer 21 extend in the vertical direction respectively. The vertical downward casting process is conducive to the long-term and lasting contact between water and oxygen-free copper when the cooling water is sprayed onto the surface of the oxygen-free copper, thereby improving the cooling effect and also being beneficial to the uniformity of the radial structure of the oxygen-free copper.

[0116] In this example, the operating temperature of the smelting furnace is greater than the operating temperature of the refining furnace 1. Furthermore, the operating temperature of the smelting furnace is 1180-1250°C, the operating temperature of the refining furnace 1 is 1100-1180°C, and the vacuum degree of the vacuum melting chamber 311 is 1×10 -2 ~20×10 -2 Pa, or 2×10 -2 ~15×10 -2 Pa, or 4 × 10 -2 ~12×10 -2 Pa et al.

[0117] In this example, the smelting furnace is a coreless induction furnace, for example, a medium-frequency coreless induction smelting furnace can be used, and the insulation and refining chamber 11 is an iron-core induction furnace, for example, an industrial-frequency iron-core induction insulation and refining furnace, that is, the above-mentioned heating mechanism 111 is the heat generating mechanism of the industrial-frequency iron-core induction insulation and refining furnace; at the same time, since the industrial-frequency iron-core induction insulation and refining furnace operates under a non-vacuum state, the surfaces of the molten copper contained in the insulation and refining chamber 11 and the buffer chamber to be cast 12 can be covered with a covering 4 that can isolate air and / or react with impurities, and the covering 4 is charcoal and / or flaky graphite; in addition, a refractory layer is provided at the bottom of the insulation and refining chamber 11, and perforated blowing bricks are pre-buried in the refractory layer, and the molten copper is refined by blowing in a reactive gas that can react with at least part of the impurities, and the reactive gas is carbon monoxide or a mixture of carbon monoxide and an inert gas. The above setting can not only protect the internal copper liquid from external pollution, but also further improve the heat preservation and refining effect and further remove impurities.

[0118] Furthermore, it can be seen from the above that the sealed flow channel 314 includes a conducting state and a blocked state. When the copper raw material 6 is vacuum-smelted in the smelting furnace of the vacuum smelting chamber 311, the sealed flow channel 314 is in a blocked state. When the expected copper liquid needs to be transferred to the refining furnace 1, the sealed flow channel 314 is in a conducting state and connected to the refining furnace 1. In other words, as mentioned above, this example adopts a combination of vacuum smelting technology and non-vacuum smelting technology. During vacuum smelting, it is avoided to be affected by the refining furnace 1 in a non-vacuum state. Therefore, it is chosen to block the sealed flow channel 314, so that the vacuum smelting process can be carried out independently, and the heat-insulating refining process and the casting process can also be carried out independently without being connected to the vacuum smelting chamber 311. When the refined copper liquid in the heat-insulating refining chamber 11 is insufficient, of course, the time required for smelting can be calculated in advance. At this time, the expected copper liquid for vacuum smelting has been melted, and the sealed flow channel is blocked. 314 is converted to a conducting state, and the expected copper liquid is transferred into the heat-insulating refining chamber 11 located outside the vacuum melting chamber 311 through the sealed flow channel 314, so as to realize continuous casting of the whole process. In fact, in this example, the amount of refined copper liquid required for casting per unit time can be controlled by controlling the number of melting furnaces and / or the amount of vacuum melting in each batch so that the heat-insulating refining chamber 11 has the amount required for casting of the buffer chamber 12 to be cast, thereby realizing continuous casting; if continuous casting is not required and intermittent casting is desired, the application or withdrawal of the first external force can also be controlled to control the amount of refined copper liquid entering the second cavity 121 to achieve the required amount for single batch casting; or, the amount of refined copper liquid contained in the heat-insulating refining chamber 11 at a time is the required amount for single batch casting. It can be seen that the method of this example can realize both continuous casting state and intermittent casting state.

[0119] In this example, when production needs to be stopped or the product needs to be changed, the molten copper in the smelting furnace and the heat-insulating refining chamber 11 can be completely emptied. When the furnace is opened next time, the molten copper is first melted in the smelting furnace and the melted copper is transferred to the molten channel in the heat-insulating refining chamber 11 to naturally fill it. Production can be continued without having to start from the melting channel. The high-purity oxygen-free copper produced by this process can reach a purity of Cu ≥ 99.99%, O ≤ 0.0003%, P ≤ 0.0003%, and H ≤ 0.0002%, meeting the requirements of TU00 or C10100 grades, while having low energy consumption and greatly improved production efficiency. In addition, because the process of this example can achieve casting in the vertical direction, the cooling effect is good during cooling crystallization, the microstructure is relatively uniform, and it can achieve the production of oxygen-free copper of larger specifications, even with a diameter greater than 300 mm.

[0120] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

[0121] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

Claims

1. A method for preparing oxygen-free copper, characterized in that: The preparation method comprises: The copper raw material is vacuum-melted in a smelting furnace in a vacuum melting chamber to remove impurities, and is melted to a desired state to obtain the desired copper liquid; The expected copper liquid is transferred into a refining furnace located outside the vacuum melting chamber through a sealed launder, the refining furnace comprising a heat-insulating refining chamber having a first cavity and a buffer chamber to be cast having a second cavity, the expected copper liquid is refined and impurities removed in the heat-insulating refining chamber to obtain refined copper liquid contained in the first cavity, the first cavity and the second cavity being in sealed communication with each other; The refined copper liquid is caused to flow out of the first cavity and upward under the action of a first external force, and then flow into the second cavity; when the first external force is weakened or removed, the refined copper liquid stops flowing into the second cavity; the first external force is controlled to act on the upper surface of the refined copper liquid and cause the refined copper liquid to separate from the first cavity from the lower portion of the heat-insulating refining chamber; The refined copper liquid entering the second chamber flows downward under the action of a second external force and enters the cold zone in the crystallizer in the vertical direction for crystallization, and oxygen-free copper is pulled out in the vertical direction, wherein the second external force includes gravity.

2. The method for preparing oxygen-free copper according to claim 1, wherein During the casting process, the magnitude of the first external force is adjusted to control the amount of the refined copper liquid flowing into the buffer chamber to be cast, thereby controlling the change in the amount of the refined copper liquid in the buffer chamber to be cast to be maintained at -3wt.% to 3wt.%.

3. The method for preparing oxygen-free copper according to claim 2, wherein The amount of the refined copper liquid in the buffer chamber to be cast is controlled to remain constant so that the refined copper liquid is cast under isobaric conditions.

4. The method for preparing oxygen-free copper according to claim 1, wherein The first external force is gas pressure, which is generated by introducing gas into the upper space of the first cavity.

5. The method for preparing oxygen-free copper according to claim 4, wherein: The gas is nitrogen and / or argon.

6. The method for preparing oxygen-free copper according to claim 1, wherein The refined copper liquid flows out from the lower part of the first cavity under the action of the first external force and flows obliquely upward, and then flows into the interior of the second cavity from the upper part or the middle part.

7. The method for preparing oxygen-free copper according to claim 1, wherein: The second external force is gravity.

8. The method for preparing oxygen-free copper according to claim 1, wherein The center line of the second cavity coincides with the center line of the crystallizer.

9. The method for preparing oxygen-free copper according to claim 8, wherein: The center line of the second cavity and the center line of the crystallizer extend in the vertical direction respectively.

10. The method for preparing oxygen-free copper according to claim 1, wherein: The operating temperature of the smelting furnace is greater than the operating temperature of the refining furnace.

11. The method for preparing oxygen-free copper according to claim 1 or 10, characterized in that: The working temperature of the smelting furnace is 1180-1250°C, and the working temperature of the refining furnace is 1100-1180°C.

12. The method for preparing oxygen-free copper according to claim 1, wherein: The vacuum degree of the vacuum melting chamber is 1×10 -2 ~20×10 -2 Pa.

13. The method for preparing oxygen-free copper according to claim 1, wherein: The smelting furnace is an iron-coreless induction furnace, and the heat-insulating refining chamber is an iron-core induction furnace.

14. The method for preparing oxygen-free copper according to claim 1, wherein: The surfaces of the molten copper respectively contained in the heat-insulating refining chamber and the buffer chamber to be cast are covered with a covering that can isolate the air and / or react with the impurities.

15. The method for preparing oxygen-free copper according to claim 14, wherein: The covering material is charcoal and / or flake graphite.

16. The method for preparing oxygen-free copper according to claim 1, wherein: The bottom of the heat-insulating refining chamber is provided with a refractory layer, and blowing bricks with holes are pre-buried in the refractory layer. The copper liquid is refined by blowing in reactive gas that can react with at least part of the impurities.

17. The method for preparing oxygen-free copper according to claim 16, wherein: The reactive gas is carbon monoxide or a mixed gas of carbon monoxide and an inert gas.

18. The method for preparing oxygen-free copper according to claim 1, wherein: The sealed flow channel includes a conducting state and a blocked state. When the copper raw material is vacuum-smelted in the smelting furnace of the vacuum smelting chamber, the sealed flow channel is in the blocked state. When the expected copper liquid needs to be transferred to the refining furnace, the sealed flow channel is in the conducting state and connected to the refining furnace.

19. The method for preparing oxygen-free copper according to claim 1, wherein: The preparation method includes a continuous casting state and an intermittent casting state; When the preparation method is in a continuous casting state, the amount of refined copper liquid required for casting per unit time is controlled by controlling the number of smelting furnaces and / or the number of vacuum smelting batches so that the amount of liquid copper in the heat-insulating refining chamber is sufficient to meet the casting requirements of the buffer chamber to be cast, thereby achieving continuous casting; When the preparation method is in an intermittent casting state, the amount of the refined copper liquid entering the second cavity is controlled by controlling the application or withdrawal of the first external force, so as to achieve the required amount for single-batch casting; or, the amount of the refined copper liquid contained in the heat-insulating refining chamber at a single time is used as the required amount for single-batch casting.

20. The method for preparing oxygen-free copper according to claim 1, wherein: The preparation method adopts an oxygen-free copper production system to prepare oxygen-free copper, and the oxygen-free copper production system comprises: Vacuum melting equipment and oxygen-free copper casting equipment for vacuum melting of copper raw materials; The vacuum melting device includes a vacuum melting chamber, a melting furnace arranged in the vacuum melting chamber, and a vacuum pumping mechanism connected to the vacuum melting chamber. The vacuum melting chamber is provided with a feeding portion for adding copper raw materials into the melting furnace and a sealed launder. The oxygen-free copper casting device includes a refining furnace and a crystallizer. The refining furnace includes an insulation refining chamber and a buffer chamber to be cast. The insulation refining chamber includes a heating mechanism for maintaining the internal temperature, a first cavity capable of communicating with the sealed flow channel, a refined copper liquid output pipe, and a gas conveying mechanism connected to the upper part of the first cavity and used to convey gas into the first cavity. The buffer chamber to be cast includes a second cavity extending in the up-down direction and a refined copper liquid input pipe connected to the upper or middle part of the second cavity. The inlet of the refined copper liquid output pipe is connected to the first cavity, the outlet of the refined copper liquid output pipe is connected to the refined copper liquid input pipe, and the height of the inlet of the refined copper liquid output pipe in the vertical direction is less than the height of the outlet of the refined copper liquid output pipe in the vertical direction. The crystallizer includes an oxygen-free copper output channel, the oxygen-free copper output channel is connected to the bottom of the second cavity, and the oxygen-free copper output channel extends in the up-down direction.

21. The method for preparing oxygen-free copper according to claim 20, wherein: The heat-insulating refining chamber also includes a receiving chamber formed with a receiving channel, the first cavity is connected to the sealed flow groove through the receiving channel, the height of the inlet of the receiving channel in the vertical direction is greater than the height of any point of the refined copper liquid input pipe in the vertical direction, and the receiving channel passes through the heating mechanism.

22. The method for preparing oxygen-free copper according to claim 21, wherein: The refining furnace further includes a docking flow channel detachably connected to the sealing flow channel, the docking flow channel is provided on the material receiving chamber and is in communication with the material receiving channel; The vacuum melting device further includes a blocking mechanism for blocking the sealed flow channel. When the copper raw material is vacuum-smelted in the melting furnace of the vacuum melting chamber, the sealed flow channel is separated from the docking flow channel, and the blocking mechanism blocks the sealed flow channel. When the expected copper liquid needs to be transferred into the refining furnace, the blocking mechanism is removed and the sealing flow channel is connected to the docking flow channel.

23. The method for preparing oxygen-free copper according to claim 20, wherein: The refined copper liquid output pipe includes a first sub-output pipe extending in the up-down direction and a second sub-output pipe connected to the first sub-output pipe and extending in the horizontal direction. The first sub-output pipe is connected to the lower end of the first cavity, and the second sub-output pipe is connected to the refined copper liquid input pipe. The acute angle between the extension direction of the first sub-output pipe and the horizontal direction is 15°-80°. The refined copper liquid input pipe extends in the horizontal direction.

24. The method for preparing oxygen-free copper according to claim 20, wherein: The second chamber includes an upper sub-chamber and a lower sub-chamber integrally formed with the upper sub-chamber. The width of the upper sub-chamber at all positions in its extension direction is the same, and the width of the lower sub-chamber at all positions in its extension direction is the same, and the width of the upper sub-chamber is greater than the width of the lower sub-chamber. The refined copper liquid inlet pipe is connected to the upper sub-chamber, and the bottom of the lower sub-chamber is provided with a refined copper liquid outlet connected to the oxygen-free copper output channel.

25. The method for preparing oxygen-free copper according to claim 20, wherein: The heat-insulating refining chamber is detachably connected to the buffer chamber to be cast. When the heat-insulating refining chamber is connected to the buffer chamber to be cast, the refined copper liquid inlet pipe is connected to the refined copper liquid outlet pipe; when the heat-insulating refining chamber is separated from the buffer chamber to be cast, the refined copper liquid inlet pipe is separated from the refined copper liquid outlet pipe.

26. The method for preparing oxygen-free copper according to claim 20, wherein: The crystallizer is detachably arranged on the buffer chamber to be cast. When the crystallizer is arranged on the buffer chamber to be cast, the center line of the oxygen-free copper output channel coincides with the center line of the second cavity.

27. The method for preparing oxygen-free copper according to claim 20, wherein: The oxygen-free copper production system includes a first state and a second state, and the vacuum melting device includes a melting state and a non-melting state; When the oxygen-free copper production system is in the first state, the vacuum melting device is in a non-melting state, and the vacuum melting device is connected or disconnected with the heat-insulating refining chamber; When the oxygen-free copper production system is in the second state, the vacuum melting device is in a melting state, and the vacuum melting device is not connected to the heat-insulating refining chamber.

28. The method for preparing oxygen-free copper according to claim 20, wherein: The smelting furnace is rotatably disposed in the vacuum smelting chamber, and the vacuum smelting device further comprises a tilting mechanism for tilting the smelting furnace, and a transfer chute located in the vacuum smelting chamber and connected to the sealed chute; The smelting furnace includes a smelting state and a tilting state. When the smelting furnace is in the smelting state, the smelting furnace and the sealed flow channel are independent of each other, and the opening of the smelting furnace faces upward; When the smelting furnace is in a tilted state, the opening of the smelting furnace is located above the transfer chute and tilted toward the transfer chute; The tilting mechanism is a first hydraulic cylinder, which includes a first cylinder body rotatably arranged in the vacuum melting chamber, a first hydraulic rod slidably arranged on the first cylinder body and extending in the up-down direction, and a first hydraulic system for driving the first hydraulic rod to perform reciprocating linear motion. The upper end of the first hydraulic rod is connected to the melting furnace, and the rotation axis of the melting furnace and the rotation axis of the first cylinder body extend in the front-to-back direction respectively and are parallel to each other.

29. The method for preparing oxygen-free copper according to claim 20, wherein: The smelting furnace includes a furnace body and a guide tube rotatably arranged in the vacuum smelting chamber, and the vacuum smelting device also includes a tilting assembly for tilting the furnace body; The conduit includes a first sub-conduit and a second sub-conduit connected to one end of the first sub-conduit, the other end of the first sub-conduit is connected to the furnace body, and one end of the second sub-conduit is connected to the sealed flow groove. The conduit can rotate relative to the sealed flow groove, and the rotation axis of the conduit coincides with the rotation axis of the furnace body. The smelting furnace includes a smelting state and a tilting state. When the smelting furnace is in the smelting state, the first sub-conduit extends in an up-down direction, and a height of one end of the first sub-conduit connected to the second sub-conduit in a vertical direction is greater than a height of the other end of the first sub-conduit connected to the furnace body. When the smelting furnace is in a tilted state, the vertical height of one end of the first sub-conduit connected to the second sub-conduit is less than or equal to the height of the other end of the first sub-conduit connected to the furnace body; The height of one end of the second sub-conduit communicating with the sealing flow groove in the vertical direction is less than or equal to the height of the other end of the second sub-conduit communicating with the first sub-conduit; The tilting assembly is a second hydraulic cylinder, which includes a second cylinder body rotatably arranged in the vacuum melting chamber, a second hydraulic rod slidably arranged on the second cylinder body and extending in the up-down direction, and a second hydraulic system for driving the second hydraulic rod to perform reciprocating linear motion. The upper end of the second hydraulic rod is connected to the melting furnace, and the rotation axis of the melting furnace and the rotation axis of the second cylinder body extend in the left-right direction respectively and are parallel to each other.

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