JP2004299974A - Method of producing high purity easily dissolvable copper oxide, high purity easily dissolvable copper oxide, copper plating material and copper plating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing high purity easily dissolvable copper oxide using a copper chloride etching waste liquid as a raw material, and to provide a copper plating material which has high easy-dissolvability and high purity. <P>SOLUTION: Sodium chloride and a metal copper material are added to a copper chloride etching waste liquid to convert cupic chloride in the waste liquid into cuprous chloride, insoluble residue contents are removed from the obtained cuprous chloride aqueous solution, and thereafter, water is added to a mother liquor to precipitate cuprous chloride. The recovered cuprous chloride powder is dipped into water, and is reacted wit chlorine to obtain a cupic chloride aqueous solution, and the cupic chloride aqueous solution is used as a raw material, so that impurities in the copper oxide powder after the production can be suppressed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing high-purity easily soluble copper oxide using a copper chloride etching waste liquid as a raw material.
[0002]
[Prior art]
As one method of performing a copper plating process on a plated object, an electrolytic plating method in which a copper plating material is supplied to an electrolytic solution (sulfuric acid, copper sulfate as a main component) and a current is passed between the insoluble anode and the plated object forming the cathode. There is a law. As a copper plating material used in this method, a copper oxide powder obtained by thermally decomposing basic copper carbonate is known. Since the copper plating material is to be appropriately replenished in the electrolytic solution, it must be readily soluble in sulfuric acid, but the copper oxide powder obtained by thermally decomposing basic copper carbonate is It is a suitable material because it is easily soluble.
[0003]
As a method for producing the copper oxide powder used as a copper plating material, a copper chloride etching solution mainly composed of cupric chloride is used, for example, chloride recovered from a factory that has performed an etching process on a copper printed circuit board or the like. A method is known in which a basic copper carbonate is generated from a copper etching waste liquid as a raw material, and then the basic copper carbonate is thermally decomposed to obtain copper oxide powder (Patent Document 1).
[Patent Document 1]
Japanese Patent No. 2753855 [0004]
[Problems to be solved by the invention]
As described above, the method of producing copper oxide powder as a copper plating material using a copper chloride etching waste liquid can effectively utilize the waste liquid, and can be compared with a case where a commercially available basic copper carbonate is used as a raw material. It is also advantageous in terms of cost. However, in the copper chloride etching waste liquid, the copper printed circuit board dissolves during the etching, and impurities contained in the copper printed circuit board, for example, Mg, Al, Si, Ca, Fe, Zn, etc. are taken into the etching liquid. Therefore, when the etching waste liquid is used as a raw material, the above-described impurity metal is mixed into the obtained copper oxide powder. If this copper oxide powder is used as a plating material, impurities accumulate in the plating bath and if left as it is, adversely affect the electroplating. Therefore, it is necessary to set up the bath before the amount of accumulated impurities reaches a predetermined amount. However, if the copper plating material (supplementary material) contains a large amount of impurities, the bath must be performed frequently, which increases the cost of the plating process and is troublesome. Therefore, it is important to remove as much of the impurities as possible at the stage of basic copper carbonate before supplying copper oxide powder as a copper plating material to the electrolytic solution, but it is difficult to sufficiently remove the impurities. In addition, it is difficult to obtain copper oxide with few impurities by oxidizing the electrolytic copper powder. Also, even in this case, it is known that the use of electrolytic copper powder requires a high cost, and that it is not easily soluble in a plating solution, so that it cannot be adopted. Further, copper hydroxide and copper oxide obtained by directly neutralizing the copper chloride etching waste liquid cannot easily separate chlorides mixed in the neutralization treatment.
[0005]
The present invention has been made in view of such circumstances, and an object of the present invention is to obtain a high-purity easily soluble copper oxide using a copper chloride etching waste liquid as a raw material, and to produce a high-purity easily soluble copper oxide. It is to provide a method. Another object is to provide a highly pure copper plating material having high solubility. Still another object is to provide a copper plating method using high-purity easily soluble copper oxide.
[0006]
[Means for Solving the Problems]
The present inventor, since many impurities in copper oxide are impurities contained in copper chloride etching waste liquid as a copper raw material, about the purification of copper chloride etching waste liquid to obtain high purity copper oxide with less impurities I did research and found the technique.
[0007]
The present invention provides a step of recovering the copper content in the copper chloride etching waste liquid as cuprous chloride, a step of reacting the cuprous chloride recovered in this step with chlorine to obtain a cupric chloride aqueous solution, A step of producing basic copper carbonate using the aqueous cupric chloride solution obtained in the step as a raw material, and then a step of thermally decomposing the basic copper carbonate to obtain copper oxide. This is a method for producing a highly soluble copper oxide having high purity.
[0008]
The step of recovering the copper content as cuprous chloride is a step of adding an alkali metal or alkaline earth metal chloride and a metal copper material to a copper chloride etching waste liquid to generate a cuprous chloride aqueous solution, Removing the insoluble residue from the cuprous chloride aqueous solution, and then adding water to the mother liquor to precipitate cuprous chloride. Here, as the chloride added to the copper chloride etching waste liquid, an inexpensive industrial salt such as sodium chloride (NaCl) is used. Further, as the metallic copper material, copper powder obtained by supplying iron powder to an etching waste liquid after etching the copper material with an etching solution containing ferric chloride as a main component can be used.
[0009]
The step of obtaining the cupric chloride aqueous solution is, for example, a step of supplying chlorine gas into water impregnated with cuprous chloride. In the step of obtaining the basic copper carbonate, for example, an aqueous solution of cupric chloride and an aqueous solution of an alkali metal or alkaline earth metal carbonate, or an aqueous solution of ammonium carbonate are mixed and reacted while heating, thereby precipitating. This is a step of separating the reaction product by filtration. The step of obtaining copper oxide is, for example, a step of thermally decomposing basic copper carbonate by heating it to 250 ° C. to 800 ° C. in an atmosphere that does not become a reducing atmosphere. Heating in a reducing atmosphere means, for example, heating not using a burner directly but using an electric furnace or the like.
[0010]
Copper oxide obtained by the production method of the present invention has high solubility and high purity, for example, as a copper plating material supplied to the electrolytic solution provided with an insoluble anode and a body to be plated serving as a cathode It can be suitably used. The present invention is also realized as a copper plating method which is a method of using high-purity easily-soluble copper oxide, and the method comprises plating the above-described high-purity easily-soluble copper oxide with an insoluble anode and a cathode. It is characterized in that it is supplied as a copper plating material to an electrolytic solution provided with a body and copper plating is performed on the body to be plated.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and 2 are explanatory views schematically showing equipment for implementing the method for producing a high-purity easily soluble copper oxide according to the present invention. Referring to FIG. An embodiment will be described. First, a copper chloride etching waste liquid, sodium chloride (NaCl), for example, an industrial salt and copper powder (Cu) are charged into the first dissolving tank 1, and the mixture is heated so that the temperature of the mixed liquid becomes, for example, 45 ° C to 55 ° C. The reaction is carried out by stirring for one hour, for example, by the stirring means 11. The heating of the mixed solution is performed by, for example, providing a bubbling unit including a diffuser tube (not shown) in the dissolving tank 1 and bubbling vapor from the bubbling unit to the mixed solution. Here, the copper chloride etching waste liquid refers to an etching solution containing hydrochloric acid containing cupric chloride as a main component, which is an etching target material made of copper, for example, cupric chloride (CuCl ₂ ) when a copper printed board surface is etched. Reacts with copper (Cu) to change to cuprous chloride (CuCl), and the concentration of cuprous chloride is increased. The composition contains, for example, 19 to 21% by weight of cupric chloride and 7 to 8% by weight of hydrochloric acid.
[0012]
In the dissolution tank 1, cupric chloride and copper powder in the waste liquid react as shown in equation (1), so that cupric chloride becomes cuprous chloride and chloride ions (Cl 2) generated from sodium chloride ^- ) The cuprous chloride reacts with the chloride ion due to the presence of ( ^- ), and is dissolved as a copper chloro complex.
CuCl ₂ + Cu → 2CuCl (1)
[0013]
After the reaction, the valve 12 is opened, and a mixed solution 13 in which a solution in which cuprous chloride is dissolved and a solution of cupric chloride are mixed is sent to suction filtration means 14, where the undissolved residue ( Undissolved copper powder and sodium chloride) are removed, and the solution and the solid are separated. The reason that cuprous chloride is dissolved with sodium chloride is that if cuprous chloride is solid, it cannot be separated from insoluble residues. Here, the processing in the first dissolving tank 1 is described as a batch type, but may be performed as a continuous processing. The separated mother liquor (solution) obtained by the solid-liquid separation is put into the diluting tank 2 together with water having a weight ratio of 10 times the weight of the separated mother liquor, and stirred by the stirring means 21 for 20 minutes, for example. Deposit copper.
[0014]
After that, the valve 22 is opened and the mixed solution 23 is sent to the suction filtration means 24, where the cuprous chloride which is a solid content is separated from the mother liquor, and the suction filtration means 24 converts the mixed solution 23 with pure water as a washing liquid. A small amount of impurities attached to the surface of cuprous chloride are washed away by washing cuprous water with water. As the cleaning liquid, pure water such as distilled water or ion-exchanged water can be used, but water having less impurities than that, for example, ultrapure water can also be used.
[0015]
After the washing, the cuprous chloride powder is charged into the reaction tank 3 in which water is stored in advance, for example, and chlorine gas is supplied into the reaction tank 3 from the bubbling means 31 such as an air diffuser. As a result, cuprous chloride is oxidized by reacting with chlorine (Cl) as shown in the formula (2) to be converted to cupric chloride (CuCl ₂ ). An aqueous cupric solution is obtained.
2CuCl + Cl ₂ → 2CuCl ₂ (2)
Thereafter, the amount of water is adjusted in the reaction tank 3 so that the copper concentration contained in the cupric chloride aqueous solution becomes 10% by weight, and the valve 32 is opened to open the cupric chloride having a copper concentration of 10% by weight. An aqueous solution of copper (CuCl ₂ ) is extracted. Then, as shown in FIG. 2, this cupric chloride aqueous solution is mixed with an alkali metal carbonate supplied from the outside, for example, an aqueous solution of sodium carbonate (Na ₂ CO ₃ ) having a sodium carbonate concentration of 12% by weight, for example. The mixture is charged into the second reaction tank 4 so that the pH of the mixture becomes 8.0, and the mixture is stirred by the stirring means 41 for, for example, 2 hours while being heated so that the temperature of the mixture is, for example, 70 ° C. to 80 ° C. Let react. The heating of the mixed solution is performed, for example, by providing a bubbling unit such as a diffuser tube (not shown) in the reaction tank 4 and bubbling steam from the bubbling unit to the mixed solution.
[0016]
The above reaction proceeds as follows. First, copper carbonate is generated as in equation (3),
Na ₂ CO ₃ + CuCl ₂ → CuCO ₃ + 2NaCl (3)
Subsequently, the copper carbonate is hydrated to form a basic copper carbonate dihydrate as shown in formula (4),
_{CuCO 3 + 3 / 2H 2 O} → 1/2 {CuCO 3 · Cu (OH) 2 · 2H 2 O} + 1 / 2CO 2 (4)
Further, as shown in the formula (5), water escapes from the dihydrate, and anhydrous basic copper carbonate is produced.
CuCO ₃ .Cu (OH) ₂ .2H ₂ O → CuCO ₃ .Cu (OH) ₂ + 2H ₂ O (5)
In this way, the basic copper carbonate is precipitated and formed into a powder and precipitated. Then, the valve 42 is opened to extract the slurry, which is a precipitate, and send it to the centrifugal separator 43 where the solid matter is separated from the mother liquor by centrifugation, and the solid matter is put in the dryer 44 for drying, and the basic carbonate is dried. Obtain copper powder.
[0017]
After obtaining the basic copper carbonate in this manner, the basic copper oxide is washed in the washing tank 45 with a washing liquid such as pure water. A small amount of impurities attached to the surface of the basic copper carbonate are washed away by washing the basic copper carbonate with, for example, pure water as a cleaning liquid.
[0018]
As a carbonate ion source, in addition to sodium carbonate, carbonates of alkali metals such as sodium hydrogen carbonate and potassium carbonate, carbonates of alkaline earth metals such as calcium carbonate and barium carbonate, or ammonium carbonate ((NH ₄ ) ₂ ) CO ₃ ) or the like can be used.
[0019]
Next, the basic copper carbonate, which is a powder, is supplied to a heating furnace, for example, a rotary kiln 5, where it is heated to a temperature of, for example, 250 ° C. or more and 800 ° C. or less to be thermally decomposed. In this example, as a heating furnace, a rotating tube 51 made of, for example, stainless steel, which rotates around the tube axis, is provided with a slight inclination. The periphery of the rotating tube 51 is surrounded by a heater 52, and the rotating tube 51 is rotated. A rotary kiln 5 for transferring basic copper carbonate powder is used. If the basic copper carbonate is heated in this way, the heating atmosphere does not become a reducing atmosphere. The reason that the basic copper carbonate is not directly heated by the burner is that, when a reducing atmosphere is used, the copper carbonate itself or the copper carbonate is decomposed into copper oxide, and then a part is reduced and the cuprous oxide (CuO ₂ ) or metallic copper ( This is because Cu) is generated, and this is avoided.
[0020]
When copper oxide is used as a copper plating material, metallic copper does not dissolve in or hardly dissolves in sulfuric acid as an electrolytic solution, becomes an insoluble residue, and requires new filtration equipment. If metallic copper or cuprous oxide is produced, the amount of replenished copper in the plating bath will not be constant, and the quality of the plated product will vary. Therefore, when heating the basic copper carbonate, it is necessary not to use a reducing atmosphere.
[0021]
Regarding the heating temperature, if the temperature is 250 ° C., for example, copper oxide can be obtained by heating for about 2 hours, but it is preferable to heat at 250 ° C. or more, in order to shorten the time of thermal decomposition and increase production efficiency. The temperature is more preferably 350 ° C. or higher. If the temperature exceeds 800 ° C., the solubility of the obtained copper oxide becomes small, so that the temperature is preferably 800 ° C. or less. In order to obtain more easily soluble copper oxide, the temperature is preferably set to 600 ° C. or lower.
[0022]
After the copper oxide is thus obtained, the copper oxide is put into the cleaning tank 6 containing pure water as a cleaning liquid, and the copper oxide is stirred and washed by the stirring means 61. Then, the valve 62 is opened to take out the mixed slurry of water and copper oxide from the washing tank 6, to remove water by the centrifugal separator 63 or the filter, and then to dry it with the drier 64 to obtain copper oxide as powder.
[0023]
In the above-described embodiment, when a metallic copper material is used as a reducing agent for cupric chloride, the copper content in the metallic copper material also becomes cuprous chloride, which ultimately leads to an increase in a copper oxide raw material. This means that even if the copper chloride etching waste liquid used as a raw material is less than the planned amount that has been recovered, the copper content in the metal copper material used as the reducing agent becomes cuprous chloride, As a result, it is possible to obtain, for example, the same amount of copper oxide as the expected amount of the copper chloride etching waste liquid that is constantly collected. Therefore, even if the available amount (return amount) of the copper chloride etching waste liquid is insufficient, a predetermined amount of copper oxide can be produced. Conventionally, the use of copper materials having relatively many impurities has been limited. However, by implementing the present invention, it is possible to remove a large amount of impurities from the copper materials. It can also be used as a raw material for products.
[0024]
Examples of the copper material having a relatively large amount of impurities include copper powder recovered from a return waste liquid of an etching solution containing ferric chloride as a main component. When a material to be etched made of copper, for example, a copper printed circuit board, is etched by this etchant, ferric chloride reacts with copper to become ferrous chloride by the reaction of the formula (6).
2FeCl ₃ + Cu → 2FeCl ₂ + CuCl ₂ (6)
[0025]
Ferrous chloride and ferric chloride are contained in the etching waste liquid, and when an iron material is added to the etching waste liquid, ferric chloride becomes ferrous chloride. Thereafter, when iron powder is added to recover the copper content in the etching waste liquid, a substitution reaction occurs as shown in equation (7), and cupric chloride is reduced to copper powder.
CuCl ₂ + Fe → Cu + FeCl ₂ (7)
[0026]
95% or more of the copper powder thus obtained is copper, but contains several thousand ppm of iron. Therefore, this copper powder cannot usually be used directly as a raw material for a copper compound, but is used as a part of a raw material for steelmaking, for example. Although the use of copper powder recovered from waste ferric chloride etching solution is limited due to its high content of impurities, it is used to recover copper in copper chloride etching waste solution as cuprous chloride. Metallic copper is used, since only the copper content plays a role in changing from cupric chloride to cuprous chloride, the above copper powder can be used as the metallic copper, thereby limiting the use. The said copper powder can be used effectively.
[0027]
Here, FIG. 3 shows an example of an apparatus for performing a copper plating method using the copper oxide generated by the present invention as a replenishing material for a copper plating material. In FIG. 3, reference numeral 8 denotes a plating bath, which is filled with a plating bath in which copper oxide is dissolved in sulfuric acid as an electrolytic solution, and which has an insoluble anode 81, for example, a titanium plate, connected to the positive electrode of the DC power source E. A coating of white metal, platinum and iridium at a ratio of 7: 3, and a material to be plated 82 such as a metal plate to be plated, which is a cathode connected to the negative electrode side of the DC power supply E, are immersed. Reference numeral 83 denotes a dissolving tank. When the amount of copper ions in the plating bath 8 becomes low, a predetermined amount of copper oxide powder is supplied into the dissolving tank 83 from a hopper 84, which is a supply source, and stirred by stirring means 85. After dissolving in sulfuric acid, the pumps P1 and P2 are operated to circulate the plating bath, and then the next copper plating process is performed. F is a filter.
[0028]
According to the above-described embodiment, instead of directly producing basic copper carbonate from cupric chloride in the copper chloride etching waste liquid, cupric chloride is temporarily changed to cuprous chloride, and Copper is changed to cupric chloride to produce basic copper carbonate using the cupric chloride as a raw material. Therefore, even if impurities are contained in cupric chloride in the copper chloride etching waste liquid, the impurities are removed at the stage of changing from cupric chloride to cuprous chloride, so the amount of impurities taken into basic copper carbonate Is suppressed as much as possible, and as a result, highly pure and easily soluble copper oxide can be obtained.
[0029]
【Example】
(Example)
350 g of sodium chloride and 120 g of copper powder were added to 1000 g of copper chloride etching waste liquid (copper concentration: about 10% by weight), and reacted at 50 ± 5 ° C. for 1 hour. After the reaction, dissolved residue was removed by performing suction filtration. 1000 g of water was added to 100 g of the obtained separated mother liquor, followed by stirring for 20 minutes. The solution was suction filtered again, and the precipitated cuprous chloride was washed with 4 times the amount of water. The cuprous chloride was added to the solution containing water, and chlorine gas was bubbled using a diffuser to oxidize cuprous chloride to cupric chloride to obtain a cupric chloride aqueous solution. Thereafter, water was added and adjusted so that the copper concentration became 10% by weight. The obtained aqueous cupric chloride solution and an aqueous solution of sodium carbonate (Na ₂ CO ₃ ) of about 12% by weight were continuously reacted at a control pH of 8.0, a reaction temperature of 75 ± 5 ° C., and a residence time of 2 hours. The reaction solution was subjected to suction filtration, and the obtained basic copper carbonate was washed with 4 times the amount of water. Next, the basic copper carbonate was heated at 500 ° C. for 2 hours to be thermally decomposed into copper oxide. When the amount of each metal impurity in the copper oxide thus obtained was examined, the results shown in the lower part of FIG. 4 were obtained. The unit of the concentration is ppm.
[0030]
(Comparative example)
Using the same copper chloride etching waste liquid as used in the examples, using the copper chloride etching waste liquid as a raw material, an aqueous solution of about 12% by weight of sodium carbonate was added to the waste liquid so that the pH became 8.0, and the reaction temperature was increased to 75%. The reaction was continuously performed at ± 5 ° C. and a residence time of 2 hours. The reaction solution was subjected to suction filtration, and the obtained basic copper carbonate was treated in the same manner as in the example to obtain copper oxide. When the amount of each metal impurity in the copper oxide thus obtained was examined, the result shown in the upper part of FIG. 4 was obtained. The unit of the concentration is ppm.
[0031]
(Discussion)
Here, regarding the copper chloride etching waste liquid and the cupric chloride aqueous solution obtained by changing cupric chloride in the waste liquid to cuprous chloride and chlorinating cuprous chloride, impurities Mg, Al, When the contents of Si, Ca, Fe, and Zn were examined, the results shown in FIG. 5 were obtained. As can be seen from the results, the cupric chloride in the copper chloride etching waste liquid is temporarily changed to cuprous chloride and further converted to cupric chloride, so to say, cupric chloride is purified. By using the purified cupric chloride as a raw material, copper oxide with few impurities was obtained, and the results shown in FIG. 4 are considered to be obtained.
[0032]
【The invention's effect】
As described above, according to the present invention, the cupric chloride in the copper chloride etching waste liquid is temporarily changed to cuprous chloride, and further, this cuprous chloride is changed to cupric chloride as a raw material. High-purity easily soluble copper oxide can be obtained while recycling. Good copper plating can be performed by using this copper oxide as a copper plating material.
[Brief description of the drawings]
FIG. 1 is a process chart showing an embodiment of a method for producing a high-purity easily soluble copper oxide of the present invention.
FIG. 2 is a process chart showing an embodiment of the method for producing a high-purity easily soluble copper oxide of the present invention.
FIG. 3 is a configuration diagram showing an example of a plating apparatus used in the plating method of the present invention.
FIG. 4 is an explanatory diagram showing the amount of impurities in copper oxide before purification and the amount of impurities in copper oxide after purification as a table.
FIG. 5 is an explanatory diagram showing the amount of impurities in a copper chloride etching waste liquid before purification and the amount of impurities in a cupric chloride aqueous solution after purification in a table.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dissolution tank 2 Dilution tank 3 Reaction tank 4 Reaction tank 43 Centrifuge 44 Dryer 45 Cleaning tank 5 Heating furnace 6 Cleaning tank 63 Centrifugal separator 64 Dryer 8 Electrolytic tank 81 Insoluble anode 82 Cathode to be plated 83 Melting Vessel 84 Hopper

Claims (9)

A step of recovering the copper content in the copper chloride etching waste liquid as cuprous chloride, a step of reacting the cuprous chloride recovered in this step with chlorine to obtain a cupric chloride aqueous solution, Producing a basic copper carbonate using the aqueous cupric chloride solution as a raw material, and then thermally decomposing the basic copper carbonate to obtain copper oxide, characterized by comprising: A method for producing copper oxide. The step of recovering the copper content as cuprous chloride includes a step of adding an alkali metal or alkaline earth metal chloride and a metal copper material to the copper chloride etching waste liquid to generate a cuprous chloride aqueous solution; Removing the undissolved residue from the aqueous cuprous solution, and then adding water to the mother liquor to precipitate cuprous chloride. Production method. 3. A copper powder obtained by supplying iron powder to an etching waste liquid after etching a copper material with an etching solution containing ferric chloride as a main component, as the metal copper material. A method for producing the high-purity easily soluble copper oxide according to the above. 4. The high purity and easy solubility according to claim 1, wherein the step of obtaining the cupric chloride aqueous solution is a step of supplying a chlorine gas into water impregnated with cuprous chloride. A method for producing copper oxide. In the step of obtaining the basic copper carbonate, an aqueous solution of a cupric chloride aqueous solution and an aqueous solution of an alkali metal or alkaline earth metal carbonate, or an aqueous solution of ammonium carbonate are mixed and reacted while heating. The method for producing high-purity easily soluble copper oxide according to any one of claims 1 to 4, which is a step of filtering and separating a reaction product. 6. The method according to claim 1, wherein the step of obtaining copper oxide is a step of thermally decomposing the basic copper carbonate by heating it to 250 ° C. to 800 ° C. in an atmosphere which does not become a reducing atmosphere. For producing highly pure and easily soluble copper oxide. A high-purity easily soluble copper oxide obtained by the production method according to claim 1. 8. A copper plating material supplied to an electrolytic solution provided with an insoluble anode and an object to be plated serving as a cathode, comprising the high-purity easily soluble copper oxide according to claim 7. The high-purity easily soluble copper oxide according to claim 7 is supplied as a copper plating material to an electrolytic solution provided with an insoluble anode and an object to be plated serving as a cathode, and the object is plated with copper. Copper plating method.

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