Ultrahigh-purity copper as well as preparation method and application thereof

Abstract

The invention relates to ultrahigh-purity copper and a preparation method and application thereof, the preparation method comprises the following steps: (1) taking a copper raw material plate as an anode and a first electrode plate as a cathode, performing first electrolysis in an alkaline electrolyte, and forming cuprous oxide on the first electrode plate to obtain the first electrode plate containing cuprous oxide; and (2) transferring the first electrode plate containing cuprous oxide into an acidic electrolyte, carrying out second electrolysis in the acidic electrolyte by taking the first electrode plate containing cuprous oxide as an anode and a second electrode plate as a cathode, forming a copper plate on the second electrode plate, taking out the second electrode plate, and stripping the copper plate to obtain the ultra-high pure copper. According to the method, stable and efficient preparation of the ultra-high-purity copper is jointly promoted by utilizing the synergistic effect of the secondary electrolysis process under the alkaline and acidic conditions. The preparation method also has the characteristics of simple process, convenience in operation and low dependence degree of product purity on raw materials, and provides more regulation and control space for subsequent process upgrading.

Description

Technical Field

[0001] The present invention relates to the technical field of copper preparation, and in particular to ultra-high purity copper and a preparation method and application thereof. Background Art

[0002] Ultra-high purity copper has excellent electrical conductivity, thermal conductivity, corrosion resistance and ductility due to its extremely small amount of impurities. These properties make it irreplaceable in the fields of integrated circuits, liquid crystal displays, aerospace, sputtering targets and ion plating. At present, the method of preparing high-purity copper usually uses 4N grade pure copper as raw material, and prepares high-purity metals through physical or chemical methods such as zone melting, vacuum distillation, electron beam melting, arc melting, electromigration, and electrochemical electrolysis.

[0003] The regional smelting technology mainly utilizes the difference in solubility of impurities in the solidified state and the molten state of the metal to promote the precipitation of impurities from the solidified state of the metal or change its distribution in the solidified state and the molten state. Prior art CN117210697A discloses a method for preparing 5N high-purity copper by regional smelting. By controlling the smelting atmosphere of multiple regional smelting, combining the special arrangement structure of the heating tube in the regional smelting furnace and the 4N cathode copper matrix, and controlling the smelting movement speed, the smelting temperature of the 4N cathode copper matrix during smelting can form a gradient, thereby facilitating the segregation of impurities in the copper matrix; and the smelting temperature can be effectively controlled by controlling the smelting speed and smelting power. Combined with a reasonable vacuum during smelting, it can effectively remove metal impurities and gases, and control the volatilization loss of the copper matrix within 1%, thereby reducing the loss of the copper matrix and improving the yield.

[0004] However, the zone melting technology is limited by the difficulty in achieving a slow change from the molten state to the solidified state of the metal in the actual production process, resulting in the inability to achieve an equilibrium state, which leads to impurities remaining in the metal during the actual production process. It is usually necessary to perform multiple melting at a slow melting zone movement rate to achieve the preparation of high-purity metals, which also leads to the purity of products obtained by zone melting in industrial production mostly maintained at the 5N level. At the same time, because the preparation of ultra-high purity metals by zone melting generally maintains a slow melting zone movement rate and requires multiple melting, this also leads to increased industrial production costs and low production efficiency.

[0005] The vacuum distillation technology for preparing ultra-high purity metals mainly utilizes the difference in saturated vapor pressure and melting point of each component in the metal rough embryo, and removes impurity elements by increasing the temperature or reducing the vacuum degree. For example, under vacuum conditions at a temperature of T = 1085 ° C, six low-melting impurities such as arsenic, phosphorus, cadmium, sulfur, zinc, and selenium can be removed; elements with vapor pressure greater than that of copper: tellurium, bismuth, manganese, tin, antimony, lead, silver, etc. will also be removed simultaneously, but usually the removal effect of five elements such as silicon, nickel, cobalt, iron, and chromium is not good, which also leads to the purity of the high-purity metal actually prepared by vacuum distillation being maintained below 6N, and limited by environmental factors in the actual production process, metal rough embryos, impurity content and other factors, the ultra-high purity metal prepared by this method cannot maintain a stable purity, forcing this method to be usually used as a supplementary means of metal purification, mainly for the preparation of 6N and above metals, but this also increases industrial costs and equipment investment, and reduces actual production benefits.

[0006] For the electrochemical electrolysis method, the anode 4N copper is mainly used, which is gradually converted into Cu in the acidic solution system under the drive of electricity. 2+ ions, and Cu 2+ Under the action of electric current, the copper is reduced and deposited as a high-purity metal element on the cathode surface. However, due to the presence of various metal impurities in 4N copper, including silver, sulfur, antimony, arsenic, phosphorus and other elements, among which the standard potential of silver is higher than that of copper, a high content of silver impurities (0.3-0.8ppm) is often present in the high-purity copper deposited at the cathode. This is also the main technical difficulty that needs to be overcome in the current process of preparing ultra-high purity copper by electrolytic copper.

[0007] In short, the above-mentioned metal purification methods are subject to uncontrollable factors such as the environment, raw materials, preparation process, and labor, which makes it difficult to stably maintain the purity of copper at an ultra-high purity level above 6N, reducing the qualified rate of ultra-high purity metal products and increasing the actual manufacturing cost of ultra-high purity metals.

[0008] Therefore, providing a method for stably preparing ultra-high purity copper with a purity of 6N or above has become an urgent problem to be solved. Summary of the invention

[0009] In order to solve the above technical problems, the purpose of the present invention is to provide an ultra-high purity copper and a preparation method and application thereof. The preparation method provided by the present invention uses crude copper as a raw material, prepares cuprous oxide under the drive of an alkaline electrolyte and an electric current in electrolysis, and then uses the obtained cuprous oxide as a raw material to electrolyze in an acidic electrolyte to prepare ultra-high purity copper, and promotes the stable and efficient preparation of ultra-high purity copper through the mutual coordination of the secondary electrolysis process under alkaline conditions and acidic conditions.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides a method for preparing ultra-high purity copper, the preparation method comprising:

[0012] (1) using the copper raw material plate as an anode and the first electrode plate as a cathode, performing a first electrolysis in an alkaline electrolyte to form cuprous oxide on the first electrode plate, thereby obtaining a first electrode plate containing cuprous oxide;

[0013] (2) transferring the first electrode plate containing cuprous oxide to an acidic electrolyte, using the first electrode plate containing cuprous oxide as an anode and the second electrode plate as a cathode, performing a second electrolysis in the acidic electrolyte to form a copper plate on the second electrode plate, taking out the second electrode plate, peeling off the copper plate, and obtaining the ultra-high purity copper.

[0014] It should be noted that, in the present invention, the "ultra-high purity copper" refers to copper with a purity greater than or equal to 99.9999wt%, that is, copper metal with a purity above the 6N level; the "copper raw material" generally uses crude copper, and its purity is less than or equal to 99.99wt%, that is, copper metal with a purity below the 4N level.

[0015] The method for preparing ultra-high purity copper by segmented electrolysis provided by the present invention first utilizes electrolysis under alkaline conditions, and under the drive of alkaline electrolyte and current in electrolysis, cuprous oxide is deposited on the first electrode plate; then, the electrode plate containing cuprous oxide is transferred to an acidic electrolyte and used as a consumable anode, and secondary electrolysis is performed under acidic conditions, and the cuprous oxide at the anode undergoes a disproportionation reaction to form divalent cupric ions and copper element through the combined action of current drive and acidic electrolyte, and at the same time, the copper element obtained by the disproportionation reaction loses electrons at the anode to form divalent cupric ions, which migrate to the cathode of the second electrode plate together with the divalent cupric ions obtained by the disproportionation reaction, and the divalent cupric ions obtain electrons at the cathode, thereby obtaining ultra-high purity copper. In addition, through the synergistic effect of the first electrolysis under acidic conditions and the second electrolysis process under alkaline conditions, it is possible to effectively remove impurity ions and prevent impurities in crude copper from entering ultra-high purity copper.

[0016] The preparation method provided by the present invention uses crude copper as a raw material, prepares cuprous oxide under the drive of an alkaline electrolyte and an electric current in electrolysis, and then uses the obtained cuprous oxide as a raw material to prepare ultra-high purity copper by electrolysis in an acidic electrolyte, and utilizes the synergistic effect of the secondary electrolysis process under alkaline and acidic conditions to jointly promote the stable and efficient preparation of ultra-high purity copper. In addition, the preparation method also has the characteristics of simple process, convenient operation, and low dependence of product purity on raw materials, which provides more control space for subsequent process upgrades.

[0017] Preferably, the copper raw material plate in step (1) comprises any one of a 4N purity copper plate or a high silver 5N copper plate.

[0018] In the copper raw material plate of the present invention, the copper purity of the "copper plate with a purity of 4N" is 99.99wt%; the "high silver 5N copper plate" refers to a material with a silver content of more than 0.5ppm and a copper purity of 99.99wt%.

[0019] Preferably, in step (1), the first electrode plate comprises any one of a titanium plate, a silicon plate, a platinum plate or a graphite plate, preferably a titanium plate.

[0020] Preferably, in step (1), the area ratio of the facing surfaces of the copper raw material plate and the first electrode plate is 1:(1-5), such as 1:1, 1:2, 1:3, 1:4 or 1:5.

[0021] Preferably, during the first electrolysis in step (1), the distance between the copper raw material plate and the first electrode plate is 0.5 to 15 cm, for example, 0.5 cm, 1 cm, 3 cm, 5 cm, 7 cm, 9 cm, 11 cm, 13 cm or 15 cm.

[0022] The distance between the cathode and cathode during the electrolysis process under alkaline conditions of the present invention affects the generation rate of cuprous oxide and the yield of the prepared copper. If the distance between the two is too close, the deposition speed is too fast and the cathode deposition is uneven; if the distance is too far, the cathode deposition speed is slow, the energy consumption increases, and the copper ions in the upper layer of the electrolyte decrease, resulting in uneven deposition and affecting the yield of ultra-high purity copper preparation.

[0023] Preferably, in step (1), alkaline electrolyte is also prepared before the first electrolysis.

[0024] Preferably, the alkaline electrolyte described in step (1) comprises a first copper salt, a buffer, an alkali solution, a stabilizer and a first solvent.

[0025] Preferably, the type of metal cations in the buffer is the same as the type of metal cations in the alkali solution.

[0026] In the alkaline electrolyte used in the preparation method of the present invention, the buffer solution is composed of a buffer agent and an alkaline solution. First, the pH of the alkaline electrolyte can be regulated and the pH value of the alkaline electrolyte can be stabilized; second, the alkaline buffer solution formed provides hydroxide ions (OH - ), the conditions of electrolysis can ensure the successful preparation of high-purity cuprous oxide; in addition, the introduction of buffer and alkali solution can also improve the conductivity of the electrolyte and reduce energy consumption. In addition, the stabilizer added to the alkaline electrolyte can complex with copper, stabilize the migration of copper between the positive and negative electrodes, and promote the formation of cuprous oxide.

[0027] Preferably, the pH of the solution in the alkaline electrolyte is 8 to 14, for example, 8, 9, 10, 11, 12, 13 or 14.

[0028] In the present invention, if the pH of the solution in the alkaline electrolyte is too low, stable cuprous oxide cannot be formed; if the pH of the solution is too high, the surface of the cuprous oxide plate will be rough.

[0029] Preferably, in the alkaline electrolyte, the concentration of copper ions in the first copper salt is 0.05-0.2 mol / L, for example, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L or 0.2 mol / L.

[0030] Preferably, the first copper salt includes any one of copper sulfate, copper nitrate or copper chloride, or a combination of at least two of them.

[0031] Preferably, in the alkaline electrolyte, the concentration of the buffer is 0.1-1 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1.0 mol / L, etc.

[0032] Preferably, the buffer comprises dipotassium hydrogen phosphate and / or disodium hydrogen phosphate.

[0033] Preferably, in the alkaline electrolyte, the concentration of the stabilizer is 0.5-2 mol / L, for example, 0.5 mol / L, 0.75 mol / L, 1.0 mol / L, 1.25 mol / L, 1.5 mol / L, 1.75 mol / L or 2 mol / L.

[0034] Preferably, the stabilizer comprises any one of lactic acid, ascorbic acid, citric acid, malic acid or amino acids, or a combination of at least two thereof.

[0035] Preferably, the first solvent comprises water.

[0036] Preferably, the concentration of the alkaline solution used to prepare the alkaline electrolyte is 1-3 mol / L, such as 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L.

[0037] Preferably, the alkali in the alkali solution comprises potassium hydroxide and / or sodium hydroxide.

[0038] Preferably, the first electrolysis in step (1) is carried out under a nitrogen atmosphere and / or an inert atmosphere.

[0039] Preferably, the gas used in the inert atmosphere includes any one of helium, argon or neon.

[0040] Preferably, the first electrolysis process in step (1) is also accompanied by stirring.

[0041] Preferably, the stirring rate is 100-500 rpm, for example, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm or 500 rpm.

[0042] As a preferred technical solution of the present invention, the first electrolysis in step (1) includes a first stage and a second stage.

[0043] Preferably, the first stage uses a forward current.

[0044] Preferably, the second stage uses reverse current.

[0045] In the preparation process of cuprous oxide, the present invention utilizes electrolysis under alkaline conditions, and under a forward current, the copper raw material plate is used as an anode for electrolysis to obtain metal ions, wherein the copper ions migrate to the cathode of the first electrode plate, and in the environment of the alkaline electrolyte, the copper ions obtain electrons at the cathode to form cuprous oxide, and then the current direction of the first electrolysis is changed to activate the cuprous oxide at the cathode of the first electrode plate, which is beneficial to the subsequent electrolysis in the acidic electrolyte, thereby improving the quality and yield of the obtained high-purity copper. If the present invention changes the specific process or parameters of the first electrolysis, the effect of the cuprous oxide obtained by electrolysis will be deteriorated, the purity will be low, and the yield of the subsequent preparation of ultra-high purity copper will also be affected.

[0046] Preferably, the specific process of the first stage includes: applying electricity to the surface of the first electrode plate, and the current density of the electricity is -0.1 to -20 mA / cm 2 The power-on time is 0.3 to 15 hours; wherein the current density is selected in the range of "-0.1 to -20 mA / cm 2 ", for example -0.1mA / cm 2 、-0.25mA / cm 2 、-0.5mA / cm 2 、-1mA / cm、-2mA / cm 2 、-5mA / cm 2 、-10mA / cm 2 、-15mA / cm 2 or -20mA / cm 2 etc.; the selection range of the power-on time is "0.3 to 15h", for example 0.3h, 0.5h, 1h, 5h, 10h or 15h, etc.

[0047] In the present invention, the “power is applied to the surface of the first electrode plate, and the current density of the power applied is -0.1 to -20 mA / cm2 " means that the direction of the current in the electrolysis process flows from the electrode where the copper raw material plate is located to the electrode where the first electrode plate is located, that is, the forward current stage. During this process, the copper ions in the electrolyte are converted into cuprous oxide and deposited on the surface of the first electrode plate.

[0048] Preferably, the specific process of the second stage includes: applying electricity to the surface of the first electrode plate, and the current density of the electricity is 0.01-20 mA / cm 2 The current density is selected in the range of "0.01-20 mA / cm 2 ", for example 0.01mA / cm 2 , 0.05mA / cm 2 , 0.1mA / cm 2 , 0.5mA / cm 2 , 1mA / cm 2 , 5mA / cm 2 , 10mA / cm 2 , 15mA / cm 2 or 20mA / cm 2 etc.; the selection range of the power-on time is "0.1~5h", for example 0.1h, 0.3h, 0.5h, 1h, 3h or 5h, etc.

[0049] In the present invention, the “power is applied to the surface of the first electrode plate, and the current density of the power is 0.01 to 20 mA / cm 2 The "current" means that the direction of the current in the electrolysis process flows from the pole where the first electrode plate is located to the pole where the copper raw material plate is located, that is, the reverse current stage. During this process, the cuprous oxide on the first electrode plate is activated.

[0050] The present invention regulates the current density of the first electrolysis, and can ensure the successful preparation of cuprous oxide and the thickness of cuprous oxide reduced by cathode. If the current density of the first stage is too small, the electrolytic copper is deposited thinly on the cathode surface, and sufficient cuprous oxide cannot be provided; if the current density of the first stage is too large, the copper deposition is thicker, the density increases, and the oxidation activity of cuprous oxide is inhibited; if the current density of the second stage is too small, the cuprous oxide cannot be activated; if the current density of the second stage is too large, after the cuprous oxide is converted into cupric oxide, the reaction will continue and be converted into a divalent copper ion complex, which is not conducive to the subsequent preparation of high-purity copper, and the target copper source of electrolysis under acidic conditions cannot be obtained.

[0051] Preferably, in step (1), the obtained first electrode plate containing cuprous oxide is further subjected to a washing treatment.

[0052] In the present invention, the number of times of the washing treatment is not specifically limited, including but not limited to 1 time, 2 times, 3 times or 4 times, etc., and those skilled in the art can select according to needs.

[0053] Preferably, an acidic electrolyte is prepared before the second electrolysis in step (2).

[0054] Preferably, the preparation process of the acidic electrolyte further includes allowing the mixed solution to stand for more than 0.5 h, for example, 0.5 h, 1 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h or 12 h.

[0055] Preferably, the acidic electrolyte in step (2) comprises a second copper salt, acid, hydrogen peroxide and a second solvent.

[0056] The acidic electrolyte of the present invention regulates the pH value of the electrolyte by acid, promotes the disproportionation reaction of cuprous oxide and ensures the successful preparation of ultra-high purity copper, and hydrogen peroxide is added to the acidic electrolyte as a dissolving agent, which can increase the dissolution of copper on the electrode surface and the oxidation performance of inert copper, thereby improving the purity and yield of ultra-high purity copper.

[0057] Preferably, the pH of the solution in the acidic electrolyte in step (2) is 0.5 to 2.0.

[0058] If the pH of the solution in the acidic electrolyte of the present invention is too low, it will affect the uniformity and density of electrolytic copper production and cause more pores to appear at the cathode; if the pH of the solution is too high, the conductivity of the electrolyte will decrease and energy consumption will increase.

[0059] Preferably, in the acidic electrolyte, the concentration of copper ions in the second copper salt is 50-150 g / L, for example, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L or 150 g / L, etc.

[0060] Preferably, the second copper salt includes any one of copper sulfate, copper nitrate or copper chloride, or a combination of at least two of them.

[0061] Preferably, in the acidic electrolyte, the concentration of the hydrogen peroxide is 0.2-2 mL / L, for example, 0.2 mL / L, 0.3 mL / L, 0.4 mL / L, 0.5 mL / L, 0.6 mL / L, 0.7 mL / L, 0.8 mL / L, 0.9 mL / L, 1 mL / L, 1.5 mL / L or 2 mL / L.

[0062] Preferably, the second solvent comprises water.

[0063] Preferably, the acid used to prepare the acidic electrolyte includes any one of sulfuric acid, nitric acid and hydrochloric acid, or a combination of at least two of them.

[0064] In the acidic electrolyte of the present invention, the acid radical ions added to the acid solution are the same as the acid radical ions of the copper salt.

[0065] Preferably, in step (2), the second electrode plate comprises any one of a titanium plate, a silicon plate, a platinum plate or a graphite plate, preferably a titanium plate.

[0066] Preferably, during the second electrolysis in step (2), the distance between the first electrode plate containing cuprous oxide and the second electrode plate is 0.5 to 15 cm, for example, 0.5 cm, 1 cm, 3 cm, 5 cm, 7 cm, 9 cm, 11 cm, 13 cm or 15 cm.

[0067] In the second electrolysis process of the present invention, if the distance between the first electrode plate containing cuprous oxide and the second electrode plate is too small, the electrolytic deposition rate is fast and the cathode plate is unevenly distributed; if the distance between the two is too large, the energy loss increases, and the copper ions cannot smoothly migrate to the surface of the second electrode plate, resulting in uneven cathode growth and affecting the yield of preparing ultra-high purity copper.

[0068] Preferably, the specific process of the second electrolysis in step (2) comprises: applying electricity to the surface of the first electrode plate containing cuprous oxide, and the current density of the electricity is 50-200 mA / cm 2 The electrolysis time is 0.3 to 15 hours; the current density is selected in the range of 50 to 200 mA / cm 2 ", for example 50mA / cm 2 , 70mA / cm 2 、90mA / cm 2 , 110mA / cm 2 , 130mA / cm 2 , 150mA / cm 2 , 170mA / cm 2 , 190mA / cm 2 or 200mA / cm 2 etc.; the selection range of the power-on time is "0.3 to 15h", for example 0.3h, 0.5h, 1h, 5h, 10h or 15h, etc.

[0069] In the present invention, the forward current direction is adopted in the second electrolysis process, that is, the current direction in the electrolysis process flows from the pole where the first electrode plate containing cuprous oxide is located to the pole where the second electrode plate is located.

[0070] In the present invention, if the current density of the second electrolysis is too small, cuprous oxide cannot be converted into copper ions and enter the electrolyte; if the current density of the second electrolysis is too large, the copper deposited at the cathode is unevenly distributed, and even impurities may appear, affecting the purity of the product.

[0071] Preferably, the temperature of the second electrolysis in step (2) is 10-45°C, for example, 10°C, 20°C, 25°C, 30°C, 35°C or 40°C.

[0072] In the present invention, the temperature of the second electrolysis is regulated within a suitable range, which can avoid the decomposition of the acid in the acidic electrolyte and prevent the generation of impurities and harmful substances. In addition, if the temperature of the second electrolysis is too high, the acid concentration of the electrolyte will decrease, affecting the purity of the obtained copper and increasing the production cost.

[0073] As a further preferred technical solution of the present invention, the method for preparing ultra-high purity copper comprises:

[0074] (I) using an alkali solution with a concentration of 1 to 3 mol / L to adjust a solution further comprising a first copper salt, a buffer, a stabilizer and a first solvent to prepare an alkaline electrolyte with a pH of 8 to 14, wherein the concentrations of substances in the formed alkaline electrolyte are as follows: the concentration of copper ions in the first copper salt is 0.05 to 0.2 mol / L, the concentration of the buffer is 0.1 to 1 mol / L, and the concentration of the stabilizer is 0.5 to 2 mol / L;

[0075] (II) In the alkaline electrolyte, a copper plate with a purity of 4N or a high silver 5N copper plate is used as an anode, and a first electrode plate is used as a cathode, nitrogen and / or an inert gas is continuously introduced into the alkaline electrolyte, and the distance between the copper raw material plate and the first electrode plate is set to be 0.5 to 15 cm, and the area ratio of the opposing surfaces of the two is 1:(1 to 5), the alkaline electrolyte is stirred at a rate of 100 to 500 rpm, and electricity is applied to the surface of the first electrode plate, and the current density of the electricity is -0.1 to -20 mA / cm 2 The first stage of electrolysis is carried out for 0.3 to 15 hours, and then the current direction is changed to pass electricity on the surface of the first electrode plate, and the current density of the electricity passing is 0.01 to 20 mA / cm 2 , performing a second stage of electrolysis for 0.1 to 5 hours to form cuprous oxide on the first electrode plate, taking out the first electrode plate obtained after the electrolysis, and washing it to obtain a first electrode plate containing cuprous oxide;

[0076] (III) using an acid solution to adjust a solution containing a second copper salt, hydrogen peroxide and a first solvent to prepare an acidic electrolyte having a pH of 0.5 to 2.0, wherein the concentration of copper ions in the second copper salt is 50 to 150 g / L, the concentration of hydrogen peroxide is 0.2 to 2 mL / L, and the prepared acidic electrolyte is allowed to stand for more than 0.5 h;

[0077] (IV) transferring the first electrode plate containing cuprous oxide obtained in step (II) to the acidic electrolyte obtained in step (III), wherein the first electrode plate containing cuprous oxide is used as an anode and the second electrode plate is used as a cathode in the acidic electrolyte, the distance between the first electrode plate containing cuprous oxide and the second electrode plate is set to be 0.5 to 15 cm, and the surface of the first electrode plate containing cuprous oxide is electrified at an electrolysis temperature of 10 to 45° C., wherein the current density of the electrification is 50 to 200 mA / cm 2 The current is applied for 0.3 to 15 hours of electrolysis to form a copper plate on the second electrode plate. The second electrode plate obtained after electrolysis is taken out, and the copper plate is peeled off to obtain ultra-high purity copper with a purity of more than 6N.

[0078] In the present invention, the timing of preparing the acidic electrolyte in step (III) is not limited. It can be performed after preparing the alkaline electrolyte in step (I), or after electrolyzing to obtain the first electrode plate containing cuprous oxide in step (II). Those skilled in the art can make the selection as needed.

[0079] In a second aspect, the present invention provides an ultra-high purity copper, which is prepared by the preparation method described in the first aspect.

[0080] The ultra-high purity copper provided by the present invention is prepared by a specific preparation method, and the total amount of metal impurities in the product is low, the purity is high and the yield is high.

[0081] Preferably, the purity of the ultra-high purity copper is 6N or above, such as 6N, 7N or 8N, that is, the purity of the ultra-high purity copper reaches 99.9999wt% or above, such as 99.9999wt% (6N), 99.99991wt% (6N1), 99.99993wt% (6N3), 99.99995wt% (6N5), 99.99997wt% (6N7), 99.99999wt% (7N), 99.999991wt% (7N1), 99.999993wt% (7N3), 99.999995wt% (7N5), 99.999997wt% (7N7) or 99.999999wt% (8N), etc.

[0082] In a third aspect, the present invention provides an application of the ultra-high purity copper as described in the second aspect, wherein the high purity copper target is used in the fields of sputtering coating, aerospace, integrated circuit chips or preparation of sputtering targets.

[0083] The ultra-high purity copper provided by the present invention can be applied to any application field of ultra-high purity copper that can be thought of by those skilled in the art.

[0084] Compared with the prior art, the present invention has at least the following beneficial effects:

[0085] (1) The preparation method provided by the present invention uses crude copper as a raw material, prepares cuprous oxide under the drive of an alkaline electrolyte and an electric current during electrolysis, and then uses the obtained cuprous oxide as a raw material to prepare ultra-high purity copper by electrolysis in an acidic electrolyte. The synergistic effect of the secondary electrolysis process under alkaline and acidic conditions is utilized to jointly promote the stable and efficient preparation of ultra-high purity copper. In addition, the preparation method also has the characteristics of simple process, convenient operation, and low dependence of product purity on raw materials, which provides more control space for subsequent process upgrades.

[0086] (2) The ultra-high purity copper provided by the present invention is prepared by a specific preparation method, and the total amount of metal impurities in the product is low and the purity is high. DETAILED DESCRIPTION

[0087] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0088] The copper raw material plates with a purity of 4N used in the following examples are derived from grade A cathode copper produced by Jinchuan Group Co., Ltd., and the purity of the copper is 99.99 wt%.

[0089] The high-silver 5N copper raw material plate used in the following examples is derived from the by-product of the production of 6N high-purity copper by Harbin Tongchuang Purun Group, wherein the silver content is 0.5 ppm and the copper content is 99.99 wt %.

[0090] The first titanium plate and the second titanium plate used in the following embodiments are both Ta2 titanium plates.

[0091] Example 1

[0092] This embodiment provides a method for preparing ultra-high purity copper, which specifically includes the following steps:

[0093] (Ι) An aqueous solution further comprising copper sulfate, dipotassium hydrogen phosphate, lactic acid and deionized water is adjusted with a potassium hydroxide solution having a concentration of 2 mol / L to prepare an alkaline electrolyte having a pH of 12 and a volume of 1000 mL, wherein the concentrations of substances in the formed alkaline electrolyte are as follows: the concentration of copper ions in the copper sulfate is 0.2 mol / L, the concentration of dipotassium hydrogen phosphate is 0.5 mol / L, and the concentration of lactic acid is 1 mol / L.

[0094] (II) In the alkaline electrolyte obtained in step (I), a copper raw material plate with a purity of 4N is used as an anode and a first titanium plate is used as a cathode. Nitrogen is continuously introduced into the alkaline electrolyte. The distance between the 4N copper raw material plate and the first titanium plate is set to 10 cm, and the area ratio of the opposing surfaces of the two is 1:3. The alkaline electrolyte is stirred at a rate of 300 rpm, and firstly, electricity is applied to the surface of the first titanium plate, and the current density of the electricity is -10 mA / cm 2 The first stage of electrolysis was carried out for 12 hours, and then the current direction was changed and the surface of the first titanium plate was energized with a current density of 10 mA / cm 2 , and a second stage of electrolysis is performed for 0.2 h to form cuprous oxide on the first titanium plate. The first titanium plate obtained after the electrolysis is taken out and rinsed twice with deionized water to obtain a first titanium plate containing cuprous oxide.

[0095] (III) A solution containing copper sulfate, hydrogen peroxide and deionized water is adjusted with sulfuric acid to prepare an acidic electrolyte with a pH of 1 and a volume of 1000 mL. In the formed acidic electrolyte, the concentration of copper ions in copper sulfate is 50 g / L, and the concentration of hydrogen peroxide is 0.5 mL / L. The prepared acidic electrolyte needs to be left to stand for 3 hours.

[0096] (IV) transferring the first titanium plate containing cuprous oxide obtained in step (II) to the acidic electrolyte obtained in step (III), using the first titanium plate containing cuprous oxide as an anode and the second titanium plate as a cathode in the acidic electrolyte, setting the distance between the first titanium plate containing cuprous oxide and the second titanium plate to be 10 cm, and applying electricity to the surface of the first titanium plate containing cuprous oxide at a current density of 100 mA / cm 2 , electrolysis is carried out for 10 hours, and the electrolysis temperature is maintained at 45°C. A copper plate is formed on the second titanium plate. The second titanium plate obtained after electrolysis is taken out, and the copper plate is peeled off to obtain ultra-high purity copper.

[0097] Example 2

[0098] This embodiment provides a method for preparing ultra-high purity copper, which specifically includes the following steps:

[0099] (Ι) A solution further comprising cupric nitrate, disodium hydrogen phosphate, ascorbic acid and deionized water was adjusted using a sodium hydroxide solution having a concentration of 1 mol / L to prepare an alkaline electrolyte having a pH of 11 and a volume of 1000 mL, wherein the concentrations of substances in the formed alkaline electrolyte were as follows: the concentration of copper ions in the cupric nitrate was 0.05 mol / L, the concentration of disodium hydrogen phosphate was 0.1 mol / L, and the concentration of ascorbic acid was 2 mol / L.

[0100] (II) In the alkaline electrolyte obtained in step (I), a high-purity 5N copper raw material plate is used as an anode, and a first titanium plate is used as a cathode. Argon gas is continuously introduced into the alkaline electrolyte. The distance between the high-purity 5N copper raw material plate and the first titanium plate is set to 1 cm, and the area ratio of the opposing surfaces of the two is 1:1. The alkaline electrolyte is stirred at 100 rpm, and first, the surface of the first titanium plate is energized, and the current density of the energization is -0.1 mA / cm 2 The first stage of electrolysis was carried out for 15 h, and then the current direction was changed and the surface of the first titanium plate was energized with a current density of 0.1 mA / cm 2 , and a second stage of electrolysis is performed for 2 hours to form cuprous oxide on the first titanium plate. The first titanium plate obtained after the electrolysis is taken out and rinsed twice with deionized water to obtain a first titanium plate containing cuprous oxide.

[0101] (III) A solution containing copper nitrate, hydrogen peroxide and deionized water is adjusted with nitric acid to prepare an acidic electrolyte with a pH of 0.8 and a volume of 1000 mL. In the formed acidic electrolyte, the concentration of copper ions in copper nitrate is 100 g / L, and the concentration of hydrogen peroxide is 1 mL / L. The prepared acidic electrolyte needs to be left to stand for 12 hours.

[0102] (IV) transferring the first titanium plate containing cuprous oxide obtained in step (II) to the acidic electrolyte obtained in step (III), using the first titanium plate containing cuprous oxide as an anode and the second titanium plate as a cathode in the acidic electrolyte, setting the distance between the first titanium plate containing cuprous oxide and the second titanium plate to be 12 cm, and applying electricity to the surface of the first titanium plate containing cuprous oxide at a current density of 50 mA / cm 2 , electrolysis was carried out for 15 hours, and the electrolysis temperature was maintained at 20°C. A copper plate was formed on the second titanium plate. The second titanium plate obtained after electrolysis was taken out, and the copper plate was peeled off to obtain ultra-high purity copper.

[0103] Example 3

[0104] This embodiment provides a method for preparing ultra-high purity copper, which specifically includes the following steps:

[0105] (Ι) An aqueous solution further comprising cupric chloride, dipotassium hydrogen phosphate, lactic acid and deionized water is adjusted with a potassium hydroxide solution having a concentration of 3 mol / L to prepare an alkaline electrolyte having a pH of 13 and a volume of 1000 mL, wherein the concentrations of substances in the formed alkaline electrolyte are as follows: the concentration of copper ions in the cupric chloride is 0.2 mol / L, the concentration of dipotassium hydrogen phosphate is 1 mol / L, and the concentration of lactic acid is 0.5 mol / L.

[0106] (II) In the alkaline electrolyte obtained in step (I), a copper raw material plate with a purity of 4N is used as an anode and a first titanium plate is used as a cathode. Nitrogen is continuously introduced into the alkaline electrolyte. The distance between the 4N copper raw material plate and the first titanium plate is set to 15 cm, and the area ratio of the opposing surfaces of the two is 1:5. The alkaline electrolyte is stirred at 500 rpm, and firstly, the surface of the first titanium plate is energized, and the current density of the energization is -20 mA / cm 2 The first stage of electrolysis was carried out for 6 hours, and then the current direction was changed and the surface of the first titanium plate was energized with a current density of 20 mA / cm 2 , and a second stage of electrolysis is performed for 0.1 h to form cuprous oxide on the first titanium plate. The first titanium plate obtained after the electrolysis is taken out and rinsed three times with deionized water to obtain a first titanium plate containing cuprous oxide.

[0107] (III) A solution containing cupric chloride, hydrogen peroxide and deionized water is adjusted with hydrochloric acid to prepare an acidic electrolyte with a pH of 1 and a volume of 1000 mL. In the formed acidic electrolyte, the concentration of copper ions in cupric chloride is 50 g / L, and the concentration of hydrogen peroxide is 2 mL / L. The prepared acidic electrolyte is left to stand for 5 hours.

[0108] (IV) transferring the first titanium plate containing cuprous oxide obtained in step (II) to the acidic electrolyte obtained in step (III), using the first titanium plate containing cuprous oxide as an anode and the second titanium plate as a cathode in the acidic electrolyte, setting the distance between the first titanium plate containing cuprous oxide and the second titanium plate to be 15 cm, and applying electricity to the surface of the first titanium plate containing cuprous oxide at a current density of 200 mA / cm 2 , electrolysis was carried out for 5 hours, the electrolysis temperature was maintained at 30°C, a copper plate was formed on the second titanium plate, the second titanium plate obtained after electrolysis was taken out, the copper plate was peeled off, and ultra-high purity copper was obtained.

[0109] Example 4

[0110] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the pH of the alkaline electrolyte is 8. The rest of the contents are the same as those in embodiment 1.

[0111] Example 5

[0112] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the pH of the alkaline electrolyte is 14. The rest of the contents are the same as those in embodiment 1.

[0113] Example 6

[0114] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the buffering agent dipotassium hydrogen phosphate of the alkaline electrolyte is omitted. The rest of the contents are the same as those in embodiment 1.

[0115] Example 7

[0116] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, lactic acid, a stabilizer of the alkaline electrolyte, is omitted. The rest of the contents are the same as those in embodiment 1.

[0117] Example 8

[0118] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the distance between the copper raw material plate and the first titanium plate in step (II) is 0.05 cm. The rest of the contents are the same as those in embodiment 1.

[0119] Example 9

[0120] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the distance between the copper raw material plate and the first titanium plate in step (II) is 16 cm. The rest of the contents are the same as those in embodiment 1.

[0121] Example 10

[0122] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the current density of the electrolysis in the first stage of step (II) is -10 mA / cm 2 Replaced with -0.01mA / cm 2 The rest of the contents are the same as those in Example 1.

[0123] Embodiment 11

[0124] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the current density of the electrolysis in the first stage of step (II) is -10 mA / cm 2 Replaced with -50mA / cm 2 The rest of the contents are the same as those in Example 1.

[0125] Example 12

[0126] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the current density of the electrolysis in the second stage of step (II) is 10 mA / cm 2 Replaced with 0.001mA / cm2 The rest of the contents are the same as those in Example 1.

[0127] Embodiment 13

[0128] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the current density of the electrolysis in the second stage of step (II) is 10 mA / cm 2 Replaced with 50mA / cm 2 The rest of the contents are the same as those in Example 1.

[0129] Embodiment 14

[0130] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the pH of the acid electrolyte in step (III) is 0.2. The rest of the contents are the same as those in embodiment 1.

[0131] Embodiment 15

[0132] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the pH of the acid electrolyte in step (III) is 3. The rest of the contents are the same as those in embodiment 1.

[0133] Example 16

[0134] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the addition of hydrogen peroxide is omitted in the acid electrolyte of step (III). The rest of the contents are the same as those of embodiment 1.

[0135] Embodiment 17

[0136] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, in step (IV), a current density of 0.01 mA / cm2 is passed through the surface of the first titanium plate containing cuprous oxide. 2 The rest of the contents are the same as those in Example 1.

[0137] Embodiment 18

[0138] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, in step (IV), a current density of 250 mA / cm2 is passed through the surface of the first titanium plate containing cuprous oxide. 2 The rest of the contents are the same as those in Example 1.

[0139] Comparative Example 1

[0140] The preparation method provided in this comparative example includes the following:

[0141] (A) sulfuric acid is used to adjust a solution containing copper sulfate, hydrogen peroxide and deionized water to prepare an acidic electrolyte with a pH of 1 and a volume of 1000 mL, wherein the concentration of copper ions in copper sulfate is 50 g / L and the concentration of hydrogen peroxide is 0.5 mL / L, and the prepared acidic electrolyte is allowed to stand for 3 hours;

[0142] (B) In the acidic electrolyte obtained in step (A), a 4N copper raw material plate is used as an anode, a titanium plate is used as a cathode, and the distance between the 4N copper raw material plate and the titanium plate is set to 10 cm. The current density is 100 mA / cm 2 The electrolysis was carried out for 10 hours with a current of 100 and the electrolysis temperature maintained at 45°C. A copper plate was formed on the titanium plate. The titanium plate obtained after the electrolysis was taken out and the copper plate was peeled off.

[0143] Comparative Example 2

[0144] The preparation method provided in this comparative example includes the following:

[0145] (a) using a potassium hydroxide solution having a concentration of 2 mol / L to adjust an aqueous solution further containing copper sulfate, dipotassium hydrogen phosphate, lactic acid and deionized water to prepare an alkaline electrolyte having a pH of 12 and a volume of 1000 mL, wherein the concentrations of substances in the formed alkaline electrolyte are as follows: the concentration of copper ions in the copper sulfate is 0.2 mol / L, the concentration of dipotassium hydrogen phosphate is 0.5 mol / L, and the concentration of lactic acid is 1 mol / L;

[0146] (b) In the alkaline electrolyte obtained in step (a), a 4N copper raw material plate is used as an anode and a first titanium plate is used as a cathode. Nitrogen is continuously introduced into the alkaline electrolyte. The distance between the 4N copper raw material plate and the first titanium plate is set to 10 cm, and the area ratio of the opposing surfaces of the two is 1:3. The alkaline electrolyte is stirred at a rate of 300 rpm, and firstly, electricity is applied to the surface of the first titanium plate, and the current density of the electricity is -10 mA / cm 2 The first stage of electrolysis was carried out for 12 hours with a current of , and the titanium plate obtained after electrolysis was taken out and the material on the anode was peeled off.

[0147] The total content of metal impurities in the final materials obtained in Examples 1-18 and Comparative Examples 1-2 and the purity of copper in the copper plate were detected. The specific detection method included: using glow discharge mass spectrometry (GD-MS) to analyze the total mass of metal impurities in the obtained materials and the purity of copper in the copper plate.

[0148] The yield of the copper plate in the preparation method provided in Example 1-18 and Comparative Example 1-2 was calculated, and the calculation formula was: the yield of the copper plate finally prepared = (the mass of the copper plate finally obtained / the anode copper plate raw material in step (II)) × 100%.

[0149] The test results are shown in Table 1.

[0150] Table 1

[0151]

[0152]

[0153] Note: "6N7" in the above Table 1 refers to a purity of 99.99997 wt%.

[0154] The test results show that:

[0155] (1) It can be seen from Examples 1 to 5 that the preparation method provided by the present invention uses crude copper as a raw material, prepares cuprous oxide under the drive of an alkaline electrolyte and an electric current in electrolysis, and then uses the obtained cuprous oxide as a raw material to prepare ultra-high purity copper by electrolysis in an acidic electrolyte. The secondary electrolysis process under alkaline conditions and acidic conditions cooperates with each other to jointly promote the stable and efficient preparation of ultra-high purity copper. Furthermore, the present invention can accelerate the deposition and growth of cuprous oxide by regulating the pH of the solution in the alkaline electrolyte, thereby obtaining high-purity copper with high yield and high purity.

[0156] (2) By comparing Example 1 with Examples 6-7, it can be seen that if the buffer is omitted in the alkaline electrolyte of the present invention, the thickness of the generated cuprous oxide is reduced, affecting the yield of the obtained copper plate; if the stabilizer is omitted in the alkaline electrolyte, the product is easily mixed with impurities, reducing the purity and yield of the obtained copper plate.

[0157] (3) By comparing Example 1 with Examples 8-9, it can be seen that in the electrolysis process under alkaline conditions of the present invention, if the distance between the copper raw material plate and the first titanium plate is too close, impurities are simultaneously adsorbed on the first titanium plate, affecting the purity of the product; if the distance is too far, the thickness of cuprous oxide is reduced, affecting the yield of the product.

[0158] (4) By comparing Example 1 with Examples 10-11, it can be seen that if the current density of the first stage of electrolysis under alkaline electrolyte conditions is too small, the thickness of cuprous oxide decreases, affecting the yield of the product; if the current density of the first stage is too large, the thickness of cuprous oxide increases, which is not conducive to electrolysis in an acidic environment and reduces the purity of the product.

[0159] (5) By comparing Example 1 with Examples 12-13, it can be seen that if the current density of the second stage of electrolysis under alkaline electrolyte conditions is too small, the activation time of cuprous oxide is insufficient, resulting in low product purity; if the current density of the second stage is too large, the thickness of cuprous oxide is reduced, resulting in reduced product purity and yield.

[0160] (6) By comparing Example 1 with Examples 14-15, it can be seen that if the pH of the solution in the acidic electrolyte of the present invention is too low, the roughness of the plate surface increases and the product purity is low; if the pH of the solution is too high, the conductivity decreases, the energy consumption increases, and the purity and yield of the obtained product deteriorate.

[0161] (7) By comparing Example 1 with Example 16, it can be seen that if the addition of hydrogen peroxide is omitted in the acidic electrolyte of the present invention, more bubbles will appear in the solution, thereby affecting the purity of the obtained copper material.

[0162] (8) By comparing Example 1 with Examples 17-18, it can be seen that if the current density of the second electrolysis in the present invention is too small, the thickness of the generated copper plate is small, the product quality deteriorates, and the purity and yield of the final product are reduced; if the current density of the second electrolysis is too large, the product will have more particles and impurities, and the purity will be reduced.

[0163] (9) By comparing Example 1 with Comparative Example 1, it can be seen that if the present invention directly adopts the process of electrolysis in an acidic electrolyte, the metal in the product cannot be removed, the impurity content increases significantly, and the purity of the product decreases significantly.

[0164] (10) By comparing Example 1 with Comparative Example 2, it can be seen that if the present invention only adopts the process of electrolysis in an alkaline electrolyte, no high-purity copper will be produced, and the product will still be cuprous oxide.

[0165] In summary, the preparation method provided by the present invention uses crude copper as raw material, prepares cuprous oxide under the drive of alkaline electrolyte and current in electrolysis, and then uses the obtained cuprous oxide as raw material to prepare ultra-high purity copper by electrolysis in acidic electrolyte, and the secondary electrolysis processes under alkaline conditions and acidic conditions cooperate with each other to jointly promote the stable and efficient preparation of ultra-high purity copper. The preparation method also has the characteristics of simple process, convenient operation, and low dependence of product purity on raw materials, which provides more control space for subsequent process upgrades. In addition, the purity of the ultra-high purity copper prepared by the preparation method of the present invention can reach more than 6N.

[0166] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing ultra-high purity copper, characterized in that: The preparation method comprises: (1) using the copper raw material plate as an anode and the first electrode plate as a cathode, performing a first electrolysis in an alkaline electrolyte to form cuprous oxide on the first electrode plate, thereby obtaining a first electrode plate containing cuprous oxide; (2) transferring the first electrode plate containing cuprous oxide to an acidic electrolyte, using the first electrode plate containing cuprous oxide as an anode and the second electrode plate as a cathode, performing a second electrolysis in the acidic electrolyte to form a copper plate on the second electrode plate, taking out the second electrode plate, peeling off the copper plate, and obtaining the ultra-high purity copper.

2. The preparation method according to claim 1, characterized in that: The copper raw material plate in step (1) comprises any one of a 4N purity copper plate or a high silver 5N copper plate; Preferably, in step (1), the first electrode plate comprises any one of a titanium plate, a silicon plate, a platinum plate or a graphite plate, preferably a titanium plate; Preferably, in step (1), the area ratio of the opposing surfaces of the copper raw material plate and the first electrode plate is 1:(1-5); Preferably, during the first electrolysis in step (1), the distance between the copper raw material plate and the first electrode plate is 0.5 to 15 cm.

3. The preparation method according to claim 1 or 2, characterized in that: The alkaline electrolyte described in step (1) comprises a first copper salt, a buffer, an alkali solution, a stabilizer and a first solvent; Preferably, the pH of the solution in the alkaline electrolyte is 8 to 14; Preferably, in the alkaline electrolyte, the concentration of copper ions in the first copper salt is 0.05 to 0.2 mol / L; Preferably, the first copper salt comprises any one or a combination of at least two of copper sulfate, copper nitrate or copper chloride; Preferably, in the alkaline electrolyte, the concentration of the buffer is 0.1 to 1 mol / L; Preferably, the buffer comprises dipotassium hydrogen phosphate and / or disodium hydrogen phosphate; Preferably, in the alkaline electrolyte, the concentration of the stabilizer is 0.5 to 2 mol / L; Preferably, the stabilizer comprises any one of lactic acid, ascorbic acid, citric acid, malic acid or amino acids, or a combination of at least two thereof; Preferably, the concentration of the alkaline solution used to prepare the alkaline electrolyte is 1 to 3 mol / L; Preferably, the alkali in the alkali solution comprises potassium hydroxide and / or sodium hydroxide.

4. The preparation method according to any one of claims 1 to 3, characterized in that: Step (1) The first electrolysis is carried out under a nitrogen atmosphere and / or an inert atmosphere; Preferably, the gas used in the inert atmosphere includes any one of helium, argon or neon; Preferably, the first electrolysis process in step (1) is accompanied by stirring; Preferably, the stirring rate is 100-500 rpm.

5. The preparation method according to any one of claims 1 to 4, characterized in that: Step (1) The first electrolysis includes a first stage and a second stage; Preferably, the first stage uses a forward current; Preferably, the second stage uses a reverse current; Preferably, the specific process of the first stage includes: applying electricity to the surface of the first electrode plate, and the current density of the electricity is -0.1 to -20 mA / cm 2 , the power-on time is 0.3 to 15 hours; Preferably, the specific process of the second stage includes: applying electricity to the surface of the first electrode plate, and the current density of the electricity is 0.01-20 mA / cm 2 , the power-on time is 0.1 to 5 hours; Preferably, in step (1), the obtained first electrode plate containing cuprous oxide is further subjected to a washing treatment.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The acidic electrolyte in step (2) comprises a second copper salt, an acid solution, hydrogen peroxide and a second solvent; Preferably, the pH of the solution in the acidic electrolyte in step (2) is 0.5 to 2.0; Preferably, in the acidic electrolyte, the concentration of copper ions in the second copper salt is 50 to 150 g / L; Preferably, the second copper salt comprises any one or a combination of at least two of copper sulfate, copper nitrate or copper chloride; Preferably, in the acidic electrolyte, the concentration of the hydrogen peroxide is 0.2 to 2 mL / L; Preferably, the acid used to prepare the acidic electrolyte includes any one of sulfuric acid, nitric acid and hydrochloric acid, or a combination of at least two of them.

7. The preparation method according to any one of claims 1 to 6, characterized in that: Step (2) the second electrode plate comprises any one of a titanium plate, a silicon plate, a platinum plate or a graphite plate, preferably a titanium plate; Preferably, during the second electrolysis in step (2), the distance between the first electrode plate containing cuprous oxide and the second electrode plate is 0.5 to 15 cm; Preferably, the specific process of the second electrolysis in step (2) comprises: applying electricity to the surface of the first electrode plate containing cuprous oxide, wherein the current density of the electricity is 50 to 200 mA / cm 2 , the power-on time is 0.3 to 15 hours; Preferably, the temperature of the second electrolysis in step (2) is 10-45°C.

8. An ultra-high purity copper, characterized in that: The ultra-high purity copper is prepared by the preparation method according to any one of claims 1 to 7.

9. The ultra-high purity copper according to claim 8, characterized in that: The purity of the ultra-high purity copper is above 6N.

10. A use of the ultra-high purity copper as claimed in claim 8 or 9, characterized in that: The ultra-high purity copper is used in the fields of sputtering coating, aerospace, integrated circuit chips or preparation of sputtering targets.

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