CA2360994A1 - Process for recovering copper from a high acid mixed metal solution - Google Patents

Abstract

This invention relates to a process for recovering copper from a high acid mixed metal solution, said high acid mixed metal solution having a pH of abo ut 0.5 or less and comprising copper ions, ions of at least one additional meta l and sulfuric acid, said process comprising: (A) separating said high acid mixed metal solution (10) into a first fraction (14) comprising copper ions and ions of said at least one additional metal, and a second fraction (16) comprising said sulfuric acid; (B) separating said copper ions from said fir st fraction; (C) forming an electrolyte solution comprising said copper ions fr om step (B); and (D) electrodepositing copper from said electrolyte solution. T he copper that is electrodeposited may be in the form of copper powder or coppe r foil.

Description

TITLE: PROCESS FOR RECOVERING COPPER FROM A HIGH ACID
MIXED METAL SOLUTION
Technical Field The present invention relates to a process for recovering copper from a high acid mixed metal solution. The copper that is recovered may be in the form of copper powder or copper foil.
Background of the Invention Mining and other industries produce numerous types of solutions containing mixed metals with high acid concentrations. Typical solutions include solutions from copper/nickel matte leaching processes, bleed solutions from electrolytic copper refineries, spent etchants from the processing of circuit boards, and the like. The compositions of these solutions is such that eletrodeposition of copper in a desired form and high purity, such as copper powder or copper foil, is not practical. The high acid concentration of these solutions renders typical selective metal recovery and purification processes, such as ion exchange, unusable. The high acid concentration of these solutions also renders neutralization of the acid with an alkali to make the solution suitable for a selective recovery and purification process, such as ion exchange, uneconomical. The copper in these solutions is currently recovered as a low value commodity product, such as grade 1 cathode, or a low purity product, such as grade 2 cathode. Direct electrodeposition of high value and high purity products, such as copper powder or copper foil, has thus far not been commercially feasible.
It would be advantageous to produce high value and high purity copper products, such as copper powder or copper foil, from such a high acid mixed metals solutions. In addition, it would be advantageous to obtain such copper products without the additional steps of first forming low-value commodity products such as grade 1 or grade 2 copper cathode which must then be further processed to form the desired high value and high purity products. The present invention provides such advantages.

Summary of the Invention The present invention provides a process for recovering copper from a high acid mixed metal solution, said high acid mixed metal solution having a pH of about 0.5 or less and comprising copper ions, ions of at least one additional metal and sulfuric acid, said process comprising:
(A) separating said high acid mixed metal solution into a first fraction comprising copper ions and ions of said at least one additional metal, and a second fraction comprising said sulfuric acid;
(B) separating said copper ions from said first fraction;
(C) forming an electrolyte solution comprising said copper ions from step (B); and (D) electrodepositing copper from said electrolyte solution.
In one embodiment, the copper that is electrodeposited is in the form of copper powder. In one embodiment, the copper that is electrodeposited is in the form of copper foil.
Brief Description of the Drawings Fig. 1 is a flow diagram illustrating one embodiment of the inventive process.
Fig. 2 is a flow diagram illustrating one embodiment of the electrodeposition step of the inventive process wherein copper powder is formed.
Fig. 3 is a flow diagram illustrating one embodiment of the electrodeposition step of the inventive process wherein copper foil is formed.
Descriation of the Preferred Embodiments Referring to Fig. 1, the inventive process comprises separating high acid mixed metal solution 10 in a first separation step 12 to form a first fraction 14 and a second fraction 16. The first fraction 14 is comprised of copper ions and ions of at least one additional metal. The second fraction 16 is comprised of sulfuric acid. The first separation step 12, in one embodiment, involves separating the fractions 14 and 16 using precepitation. In another embodiment, acid retardation is used in the first separation step 12 to separate the fractions 14 and 16. The second fraction 16 may be recycled or discarded. The first fraction 14 is subjected to a second separation step 18 wherein copper ions 20 are separated from the first fraction. The remaining portion 22 of the first fraction is comprised of one or more additional metals. Remaining portion 22 may be subjected to further treatment to recover one or more of the additional metals, recycled or discarded. In one embodiment, precipation is used in the second separation step 18 to effect the desired separation. In one embodiment, separation is effected in the second separation step 18 using a copper selective ion exchange resin. The separated copper 20 is dissolved in sulfuric acid to form an electrolyte solution and electrodeposited copper 24 is separated from the electrolyte solution in an electrodeposition step 26. Spent electrolyte 28 from the electrodeposition step may be recycled or discarded. The electrodeposited copper 24 is a high purity copper product which may be in the form of copper powder or copper foil.
The high acid mixed metal solutions that are treated in accordance with the inventive process have a pH of about 0.5 or less and are comprised of copper ions, ions of at least one additional metal, and sulfuric acid. The additional metal may be antimony, arsenic, bismuth, cobalt, iron, nickel, lead, tin, zinc, or a mixture of two or more thereof. In one embodiment, these additional metals may be regarded as impurities since the desired metal is copper and the concentration of such additional metals in the high acid mixed metal solution is less than the concentration of the copper.
The high acid mixed metal solution may have a copper ion concentration in the range of about 1 to about 300 grams per liter, and in one embodiment about 5 to about 300 grams per liter, and in one embodiment about to about 200 grams per liter. The concentration of ions of the additional metal or metals may be in the range of about 1 to about 100 grams per liter, and in one embodiment about 5 to about 100 grams per liter, and in one embodiment about 10 to about 50 grams per liter. The sulfuric acid 30 concentration may be in the range of about 50 to about 400 grams per liter, and in one embodiment about 75 to about 250 grams per liter. The pH is typically about 0.5 or less, and in one embodiment it is about 0.3 or less, and in one embodiment about 0.1 or less, and in one embodiment it is zero The high acid mixed metal solution may be taken from any source.
In one embodiment, it is a copper/nickel matte leaching solution, a bleed solution from an electrolytic copper refinery, or spent etchant from the processing of circuit boards.
Steps (A) (B) and (C) Step (A) of the inventive process involves, in one embodiment, precipitating crude copper sulfate crystals from the high acid mixed metal solution. In this embodiment, the high acid mixed metal solution is first heated to an elevated temperature in the range from about 75°C to about 95°C, and in one embodiment about 80°C to about 90°C. During this heating step, a portion of the water in the high acid mixed metal solution is evaporated. In one embodiment, about 5 to about 70% by weight of the water is evaporated, and in one embodiment about 15 to about 40% by weight of the water is evaporated. The heated solution is then cooled to a temperature in the range from about 0°C to about 30°C, and in one embodiment about 5°C to about 25°C, and in one embodiment about 10°C to about 25°C.
This cooling step results in the formation of a precipitate which is in the form of crude copper sulfate crystals or solids.
The copper sulfate which precipitates from the high acid mixed metal solution is referred to as crude copper sulfate due to the fact that it is impure. The crystals or solids of copper sulfate are intermixed in a slurry or sludge. The crude copper sulfate crystals or solids may not be crystalline except on a microscopic scale.
When the temperature is reduced, the copper sulfate precipitates, but a substantial portion of the additional metals remain in solution. This is because the solubility of the copper sulfate is exceeded when the solution is cooled, but the solubility of the additional metals is generally not exceeded.
Thus, by precipitating the copper sulfate, a substantial portion of the additional metals are separated from the copper sulfate. The separated additional metals may be further processed or discarded. However, a portion of the additional metals remains intermixed with the copper sulfate.
As part of the precipitation step, the crude copper sulfate crystals or solids are separated from the remaining high acid mixed metal solution using 5 known solid-liquid separation techniques, such as filtering through quartz sand or a fritted glass filter. The filtrate may be recycled or discarded.
Step (B) of the inventive process, in one embodiment, involves precipitating the remaining additional metals from the crude copper sulfate crystals or solids. In this step, the crude copper sulfate crystals or solids are redissolved in water to provide an aqueous crude copper sulfate solution. Due to the relatively acidic character of copper sulfate and to the presence in the crude crystals or solids of small amounts of residual acid remaining from the high acid mixed metal solution, the pH of the aqueous crude copper sulfate solution is typically in the range of about 1 to about 2. At such pH levels, the remaining additional metals typically remain in solution.
At a pH above the range of about 1 to about 2 for the aqueous crude copper sulfate solution, i.e., at a pH of about 3 to about 4, many of the additional metals are not soluble, while copper sulfate remains in solution.
Accordingly, in one embodiment, this precipitation step includes the adding of alkali with agitation to raise the pH to a level in the range of about 3 to about 4. The alkali that may be added may be sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium chloride, potassium hydroxide, potassium carbonate, potassium bicarbonate, potassium chloride, or a mixture of two or more thereof. As the pH increases to a value of about 3 to about 4, metals such as iron, arsenic, antimony, nickel, lead, platinum, gold, silver, and the like precipitate, since they are not soluble at such pH levels. Thus, this precipitation step involves increasing the pH to about 3, and in one embodiment the pH is increased to about 3.5, and in one embodiment the pH is increased to about 3.8, and in one embodiment it is increased to about 4, to precipitate out the foregoing additional metals.

The copper sulfate solution is then subjected to a solid-liquid separation step from which a solid containing a substantial portion of the additional metals is separated. The separated solids may be discarded or subjected to further processing. The liquid obtained from this step is a purified copper sulfate solution. This purified copper sulfate solution is sufficiently pure for use in the electrodeposition step of the inventive process. The purified copper sulfate solution, which may be referred to as the electrolyte solution formed in step (C) of the inventive process, may have a copper ion concentration in the range of about 1 to about 200 grams per liter, and in one embodiment about 1 to about 60 grams per liter, and in one embodiment about 50 to about 150 grams per liter. The concentration of the one or more additional metals may range up to about 1000 parts per million, and in one embodiment up to about 200 parts per million. The sulfuric acid concentration may be in the range of about 10 to about 300 grams per liter, and in one embodiment about 10 to about 200 grams per liter, and in one embodiment about 50 to about 300 grams per liter.
Examale 1 A high acid mixed metal solution is heated to 80°C to evaporate water and then cooled to 22°C in an agitated container to form a precipitate.
The precipitate solids that are formed are recovered by filtration. The solids are weighed and sampled, then washed with a small amount of water, and then weighed and sampled again. Analysis of the initial high acid mixed metal solution, filtrate, unwashed and washed solids is provided in Table I.

Table I
Initial Filtrate Unwashed Washed Solution Solids Solids 9/I g/I

pH 3.25 Cu 121 41.9 22.48 24.76 Ni 13.6 17.4 0.35 0.14 Co 1 1.1 13.8 0.39 0.23 Fe 6.23 7.26 0.31 0.20 As 3.83 5.25 0.064 0.0076 Bi 0.13 0.18 0.0047 0.0037 Pb 0.032 0.029 0.002 0.001 Sb 0.149 0.056 0.0047 0.0037 Se 0.0017 0.0025 0.0003 0.0002 Sn 0.011 0.001 0.0018 0.0021 Te 0.0028 0.0016 0.0003 0.0002 As shown in Table I, a significant portion of the copper is removed from the high acid mixed metal solution, while the levels of additional metals are significantly reduced, particularly in the washed solids. The washed solids are, however, relatively impure and not suitable for electrodeposition of relatively high purity copper products such as copper powder or copper foil. The washed solids are redissolved in water with the pH of the resulting solution being in the range of about 1 to about 2. When the pH is increased by addition of alkali to a pH of about 4, a substantial portion of the additional metals precipitate out, while the copper remains in solution.
In another embodiment of the invention, during step (A) of the inventive process the high acid mixed metal solution is subjected to an acid retardation step to remove a large proportion of the acid, leaving behind a less acidic solution of copper and one or more additional metals. Acid retardation processes are known in the art. In such processes polymeric resin materials are used to sorb sulfuric acid while excluding metal salts. The sorbed acid is then recovered by water elution for reuse. A commercially available process that may be used is the APU System which is available from Eco-Tec Inc. of Ontario, Canada. Briefly, this process involves the use of a column containing a fixed resin bed. There are two steps to the process, namely, the "upstroke" and the "downstroke." During the upstroke, the high acid mixed metal solution is pumped into the bottom of the column. As the solution flows upwardly through the resin bed, acid is sorbed by the resin and the remaining de-acidified metallic salt solution, designated arbitrarily as the "byproduct" is collected from the top of the bed. Next during the downstroke, water is pumped into the top of the bed, and as it flows downwardly through the bed it desorbs acids from the resin so that the purified acid "product" is collected from the bottom of the bed.
Examples of polymeric resin materials that may be used include Petrolite A-100 (a product of Petrolite identified as a macroporous polystyrene divinyl benzene resin having quaternary amine functionality). The byproduct stream may be referred to as the recovered copper stream. This recovered copper stream may have a copper ion concentration in the range of about 1 to about 200 grams per liter, and in one embodiment about 1 to about 60 grams per liter, and in one embodiment about 50 to about 150 grams per liter; an additional metal ion concentration of about 2 to about 50 grams per liter, and in one embodiment about 5 to about 30 grams per liter; and a sulfuric acid concentration in the range of about 5 to about 30 grams per liter, and in one embodiment about 10 to about 20 grams per liter.
Example 2 The following Table II shows the results obtained when acid retardation is applied to a high acid mixed metal solution using an APU
System.

Table II
Component Feed Byproduct Product (g/I) (g/I) (g/I) H2S04 165 12.5 142 Cu 40 17 6 N~ 10 4.35 1.5 As 5 2.25 12.7 As shown in Table II, the acid retardation step removes a significant portion of the sulfuric acid, and provides a byproduct or recovered copper stream with a relatively low acid concentration but with a relatively high proportion of the copper, nickel and arsenic which were contained in the feed. While the recovered copper stream contains a relatively high concentration of copper, it is contaminated with a significant concentration of additional metals (i.e., nickel and arsenic) and cannot be used in the desired electrodeposition step for making high purity copper products such as copper powder or copper foil.
During step (B) of this embodiment of the present invention, the recovered copper stream from the acid retardation step is advanced through a bed of an ion exchange resin that preferentially extracts copper ions relative to the other metals in the stream. The resins are typically small granular or bead-like materials consisting of two principal parts: a resinous matrix serving as a structural portion, and an ion-active group serving as the functional portion.
The functional group is selected from those functional groups that are reactive with copper ions. Examples of such functional groups include -S03-, -COO-, ~ I

N
and I

N
5 Useful resin matrixes include the copolymers of styrene and divinylbenzene.
Examples of commercially available resins that may be used include IRC-718 (a product of Rohm & Haas identified as a tertiary amine substituted copolymer of styrene and divinylbenzene), IR-200 (a product of Rohm & Haas identified as sulfonated copolymer of styrene and divinylbenzene), IR-120 (a product of Rohm 10 & Haas identified as sulfonated copolymer of styrene and divinyl benzene), XFS
4196 (a product of Dow identified as a macroporous polystyrene/divinylbenzene copolymer to which has been attached N-(2-hydroxyethyl)-picolylamine), and XFS 43084 (a product of Dow identified as a macroporous polystyrene/divinylbenzene copolymer to which has been attached N-(2-hydroxypropyl)-picolylamine). These resins may be used in the inventive process as fixed beds or moving beds.
The copper selective ion exchange step may be operated on a batch basis. A quantity of the recovered copper stream from the acid retardation step containing a quantity of copper approximately equal to the copper-retention capacity of the copper selective ion exchange resin in the copper-selective ion exchange column is provided to the ion exchange column as a batch. This capacity may be determined empirically based on the known quantities in the system, or may be calculated on a batch basis. In either case, a quantity of the recovered copper stream from the acid retardation step is passed through the ion exchange column until the copper-retention capacity is reached. The column may then be washed to remove remaining small quantities of the other metals, but leave the copper on the resin.
A second ion exchange column may be set up in a series or parallel arrangement, such that when copper break-through occurs from the first column, the flow, including the material which has broken through, may be switched to the second column. As would be recognized by a person of skill in the art, a plurality of ion exchange columns may be employed, including columns with resins selective for ions of one or more of the additional metals.
The copper ions may be extracted from the ion exchange resin by washing the resin with a sulfuric acid solution. The resulting solution, which may be referred to as the electrolyte solution formed in step (C) of the inventive process, may have a copper ion concentration in the range of about 1 to about 200 grams per liter, and in one embodiment about 1 to about 60 grams per liter, and in one embodiment about 50 to about 150 grams per liter; an additional metal ion concentration of up to about 1000 parts per million, and in one embodiment up to about 200 parts per million; and a sulfuric acid concentration of about 10 to about 300 grams per liter, and in one embodiment about 10 to about 200 grams per liter, and in one embodiment about 50 to about 300 grams per liter.
Stea (D) to Make Copper Powder In one embodiment, copper powder is formed during the electrodeposition step (D) of the inventive process. In this embodiment, copper powder is electrodeposited in an electroforming cell equipped with a plurality of cathodes and anodes. Typically the cathodes are vertically mounted, have flat surfaces, and have square or rectangular shapes. The anodes are adjacent to the cathodes and are typically in the form of flat plates having the same shape as the cathodes. The gap between the cathodes and the anodes is typically from about 1 to about 4 inches, and in one embodiment about 1.5 to about 3 inches, and in one embodiment about 1.75 inches. The anode may be a dimensionally stable anode that is made of, for example, lead, lead alloy, or titanium coated with a platinum family metal (i.e., Pt, Pd, Ir, Ru) or oxide thereof. The cathode may be constructed of titanium or stainless steel and typically has smooth surfaces on each side for receiving the electrodeposited copper powder.
The electrolyte solution flows in the gaps between the anodes and cathodes, and an electric current is used to apply an effective amount of voltage across the anodes and the cathodes to deposit copper on the cathodes. The electric current may be a direct current or an alternating current with a direct current bias. In one embodiment, the flow of the electrolyte solution through the electroforming cell is sufficient to maintain a constant desired difference in copper ion concentration between electrolyte solution entering the cell and the electrolyte solution leaving the cell. This difference in copper ion concentration may be from about 1 to about 10 grams per liter, and in one embodiment about 1 to about 3 grams per liter, with the solution entering the electroforming cell having a higher concentration of copper ions than the solution leaving the cell.
The flow between the anode and the cathode may be effected by natural convection. In one embodiment, the flow rate is in the range of about 0.01 to about 0.3 gallons per minute per square foot of immersed cathode surface area (gpm/csa), and in one embodiment about 0.1 to about 0.2 gpm/csa. The electrolyte solution may have a free sulfuric acid concentration in the range of about 50 to about 300 grams per liter, and in one embodiment 100 to about 250 grams per liter, and in one embodiment about 120 to about 190 grams per liter. In one embodiment, the temperature of the electrolyte solution in the electroforming cell is in the range of about 15°C to about 65°C, and in one embodiment about 20 ° C to about 45 ° C. The copper ion concentration may be in the range of about 1 to about 60 grams per liter, and in one embodiment 2 to about 30 grams per liter, and in one embodiment about 4 to about 25 grams per liter. The current density may be in the range of about 20 to about 300 amps per square foot (ASF), and in one embodiment about 30 to about 200 ASF, and in one embodiment about 50 to about 150 ASF.
The free chloride ion concentration in the electrolyte solution may be in the range of up to about 100 parts per million (ppm), and in one embodiment up to about 50 ppm, and in one embodiment up to about 20 ppm, and in one embodiment about 0.05 to about 20 ppm, and in one embodiment about 0.05 ppm to about 15 ppm, and in one embodiment about 0.05 ppm to about 12 ppm. A method for measuring low concentrations of chloride ion in the electrolyte solution involves the use of multiple known additions of CI' on an Orion 960 Autochemistry System. The system has an Orion model 94-17B

chloride electrode and an Orion model 90-02 double junction reference electrode. The precision of the method is 2%. The method is capable of measuring CI- concentrations below 1 ppm in the electrolyte. It may be improved by adding a known concentration of CI-, for example 5 ppm, to the solution containing the unknown quantity of CI- prior to the measurements. The 5 ppm addition is then subtracted from the CI- concentration determined by the Orion 960 Autochemistry System.
The impurity level in the electrolyte solution may be maintained at a level of no more than about 1 gram per liter, and in one embodiment no more than about 0.8 gram per liter, and in one embodiment no more than about 0.6 gram per liter, and in one embodiment no more than about 0.4 gram per liter, and in one embodiment no more than about 0.2 gram per liter, and in one embodiment no more than about 0.1 gram per liter. The term "impurity" refers to any material that is not intentionally added to the electrolyte solution during the electrodeposition step of the inventive process. Included among the impurities that are to be avoided, or limited as indicated above, are the additional metals (i.e., cobalt, platinum, gold, iron, nickel, bismuth, tin, lead, antimony , arsenic, zinc, silver, sodium) as well as nitrates, phosphates, sulfides, and the like. In one embodiment, the concentration of iron is maintained at a level of no more than about 0.2 gram per liter, and in one embodiment no more than about 0.1 gram per liter.
The electrolyte solution may containe one or more organic additives which are used for the purpose of altering the properties or characteristics of the copper powder. Examples of the organic additives that may be added include:
gelatins derived from collagen such as animal glue; organic sulfur- containing materials such as the thioureas and the iso-thiocyanates (e.g., thiourea, thiosinamine, thiosemicarbazide, etc.); organic sulfonates such as ammonium lignosulfonate; and the triazoles such as benzotriazole and the substituted benzotriazoles including the alkyl substituted benzotriazoles (e.g., tolyltriazole, ethylbenzotriazole, hexylbenzotriazole, octylbenzotriazole, etc.) aryl-substituted benzotriazole (e.g., phenylbenzotriazoles, etc.) and alkaryl- or arylalk-substituted benzotriazole, and substituted benzotriazoles wherein the substituents may be, for example, hydroxy, mercapto, alkoxy, halo (e.g., chloro), nitro, carboxy or carbalkoxy. These organic additives may be added at concentrations of up to about 20 grams per liter, and in one embodiment up to about 10 grams per liter.
In one embodiment, the electrolyte solution is free of any organic additives. That is, no organic additives are added. In this embodiment minor or trace amounts of the foregoing organic materials may appear as impurities in the electrolyte solution, but the amount of such organic material is maintained below about 0.5 ppm, and in one embodiment below about 0.2 ppm, and in one embodiment below about 0.1 ppm, and in one embodiment below about 0.05 ppm.
Electrodeposition is conducted until the desired build up of copper powder on the cathodes is achieved. In one embodiment, electrodeposition is continued for about 1 to about 5 hours, and in one embodiment about 1 to about 3 hours. Electrodeposition is then discontinued and the powder is removed from the cathodes. The powder may be removed from the cathodes by brushing or scraping or using vibration or other mechanical and/or electrical techniques known in the art. The powder may be removed by reversing the current on the cathodes. The powder may be removed by spraying water or electrolyte onto the cathodes as the cathodes are lifted out of the electroforming cell, or by spraying electrolyte onto the cathodes without removing them from the cell. The powder may be separated from the cathodes by inducing turbulent flow in the electrolyte, or by mechanically scraping the powder from the cathodes. The powder may be separated by vibrating the cathode using ultrasonic energy or by manually or mechanically pounding on the cathode.
In one embodiment, the copper powder that is separated from the cathodes is washed sufficiently to remove electrolyte from the powder. Various methods may be employed to wash the powder. One method involves washing the powder and then dewatering it using a centrifuge. During this process antioxidants may be added to prevent or reduce oxidation. The antioxidants that may be added include ammonium hydroxide. These antioxidants may be added to the wash water at a sufficient concentration to provide the wash water with a pH of about 7 to about 14, and in one embodiment a pH of about 9. In one embodiment, antioxidants are added at a concentration of about 0.2 to about 0.9 gram per liter of wash water, and in one embodiment about 0.4 to about 5 0.6 gram per liter.
In one embodiment, an effective amount of a stabilizer is adhered to the surface of the copper powder for the purpose of reducing oxidation and increasing shelf life. Examples of the stabilizers that may be used include the triazoles such as benzotriazole and substituted benzotriazoles. The substituted 10 triazoles include alkyl-substituted benzotriazole (e.g., tolyltriazole, ethylbenzotriazole, hexylbenzotriazole, octylbenzotriazole, etc.) aryl-substituted benzotriazole (e.g., phenylbenzotriazole, etc.), and alkaryl- or arylalk-substituted benzotriazole, and substituted benzotriazoles wherein the substituents may be, for example, hydroxy, mercapto, alkoxy, halo (e.g., chloro), nitro, carboxy or 15 carbalkoxy. The alkylbenzotriazoles include those in which the alkyl group contains 1 to about 20 carbon atoms, and in one embodiment 1 to about 8 carbon atoms. The concentration of these stabilizers in the wash water may be up to about 10,000 ppm, and in one embodiment from about 0.5 to about 1000 ppm, and in one embodiment from about 0.5 to about 500 ppm, and in one embodiment from about 0.5 to about 70 ppm.
In one embodiment, a surfactant is added to the stabilizer to enhance the wetting of the copper powder and/or enhance dispersion of stabilizer. In one embodiment, the surfactant is a nonionic surfactant. The surfactants that may be used include the block copolymers of ethylene oxide and propylene oxide generally available for surfactant applications. These are sometimes referred to as alkoxylated alcohols. Examples of commercially available surfactants that can be used include those available from Olin under the trade designation Poly-Tergent. Specific examples include Poly-Tergent S-505LF (a nonionic, low foaming surfactant identified as a block copolymer of ethylene oxide and propylene oxide). The concentration of the surfactant in the stabilizer may be in the range up to about 500 ppm, and in one embodiment about 5 to about 500 ppm, and in one embodiment about 100 to about 500 ppm, and in one embodiment about 150 to about 250 ppm.
In one embodiment, the copper powder is washed using an antioxidant containing wash water in a first step, and then washed again using a stablizer-containing wash water which optionally may contain a surfactant.
The dewatered copper powder may then be dried using conventional copper powder drying techniques. The drying techniques that may be used include vacuum drying, flash drying, fluidized bed drying, rotary kiln/multi hearth drying, or freeze drying. The copper powder may be dried at a temperature of about 25 to about 125°C, and in one embodiment about to about 85°C, and in one embodiment about 45 to about 55°C. The copper powder may be dried in air, in an inert atmoshpere, or in a vacuum at an absolute pressure in the range of about 0.1 to about 760 mmHg, and in one embodiment 1 to about 250 mmHg, and in one embodiment about 3 to about 10 mmHg. Agglomerates that form during drying may be broken using known agglomerate breaking techniques. For example, screens, cage mills, cascading screens, and the like, can be used. The powder can be separated into desired size fractions using standard separation techniques such as screening and then collected and packaged.
The apparent density of the powder may be increased or decreased, if desired, by blending it with higher or lower density powders. The powder may be milled (e.g., hammer mill) or rolled. These and similar techniques are known in the art.
The properties of copper powder produced by the inventive process are dependent on various characteristics of the operation and, therefore, can often be controlled by altering certain process variables. For example, purity can be high, with copper contents that can exceed, for example, about 99.5% by weight or about 99.9% by weight, if such high purity levels are required. In this regard, an advantage of the inventive process is that the purity level of the electrolyte that is used in step (D) can be controlled. It is also possible to produce copper powder with lower purity levels, for example, as low as 95%

by weight copper, or as low as 97% by weight copper, or as low as 99% by weight copper, if economics and the requirements for the copper powder that is produced permit such lower levels of copper purity.
Particle size distribution for the copper powder may be varied over a wide range. For example, the -325 mesh fraction can be varied from about 5% to about 90% by weight. Apparent densities of the powder may be in the range of, for example, about 0.2 to about 4 g/cm3, and in one embodiment about 0.7 to about 3.2 g/cm3. Typical flow rates may range from about 10 to about 75 seconds for a 50-gram sample, and in one embodiment about 20 to about 65 seconds.
Green density is a function of the compacting pressure. For example, the green density may rise from about 7 to about 8 g/cm3 as the compacting pressure is increased from about 20 to about 40 tons per square inch (tsi). Green strength increases with the compacting pressure. For example, the green strength may rise from less than about 2200 psi up to about 3500 psi as the compacting pressure is increased from about 20 to about 40 tsi.
Particle shape of the copper metal powder is generally dendritic when deposited on the cathode. During subsequent operations, however, the dendrites tend to become rounded.
Referring now to Fig. 2, an apparatus and process for electrodepositing copper powder is disclosed. The apparatus used with this process includes a mixing vessel 100, filters 102 and 104, an electroforming cell 106, holding vessel 108, centrifuge 1 10, drier 1 12, agglomerate breaker 1 14, screens 1 16, and storage hoppers 1 18, 120 and 122. The electroforming cell 106 includes vessel 124, vertically mounted anodes 126, and vertically mounted cathodes 128. Copper from step (B) of the inventive process enters vessel 100, as indicated by directional arrow 132. Sulfuric acid may be added to vessel 100, as indicated by directional arrow 134. Chloride ions and/or organic additives may be added as indicated by directional arrow 136. Dilution water may be added as indicated by directional arrow 138. Spent electrolyte solution 130 is recycled from electroforming cell 106, through lines 140 and 142 and enters vessel 100; this spent electrolyte may be filtered in filter or it may by-pass filter 104 through line 144. The foregoing streams are mixed in vessel 100 to form electrolyte solution 130. Fresh electrolyte solution 130 is advanced from vessel 100 to vessel 124 through lines 146 and 148. The electrolyte solution 130 may be filtered in filter 102 prior to entering vessel 124 or, alternatively, it may by-pass filter 102 using line 1 50. Impurities may be removed using filters 102 and/or 104.
The electrolyte solution 130 flows between the anodes 126 and cathodes 128. A voltage is applied between anodes 126 and cathodes 128 to effect electrodeposition of copper powder 152 on each side of the cathodes.
Electrodeposition of copper powder 152 on cathodes 128 is continued until the desired amount of copper powder has deposited on the cathodes. Electro-deposition is then discontinued. Spent electrolyte solution 130 is drained from vessel 124 and advanced to vessel 100 through lines 154 and 156. The copper powder 152 is separated from the cathodes 128 by spraying water or electrolyte on to the cathode resulting in the formation of a slurry 158 in the lower cone shaped section 160 of vessel 124. The slurry 158 is advanced from vessel 124 to vessel 108 through lines 154 and 162. The slurry 158 is then advanced from vessel 108 to centrifuge 110 through line 164. In centrifuge 1 10, liquid effluent is separated from the copper powder and exits centrifuge 1 10 through line 169 and is either recycled to vessel 108 through line 170, or removed through line 172 where it is discarded or subjected to further processing. In one embodiment, an antioxidant is added to the powder in the centrifuge as indicated by directional arrow 166. In one embodiment, a stabilizing agent is added to the powder in the centrifuge as indicated by directional arrow 168. In one embodiment, the antioxidant and stabilizing agent are added to the powder in the centrifuge in sequential order with the antioxidant preceding the stabilizing agent. When the antioxidant and/or stabilizing agent is added to the powder in centrifuge 110, the centrifuge is rotated at a sufficient rate to place a centrifugal force of about 2 to about g's (one "g" is equal to the force of gravity) on its contents, and in one embodiment about 10 to about 200 g's, and in one embodiment about 10 to about 75 g's, until the pH of the effluent is in the range of about 7 to about 14, and in one embodiment about 7 to about 1 1. The rotation rate of the centrifuge is then increased to dewater the copper powder. During this dewatering step, the rotation rate of the centrifuge is increased to a sufficient level to place a centrifugal force on its contents in the range of about 200 to about 750 g's, and in one embodiment about 500 to about 750 g's, and in one embodiment about 650 to about 700 g's. The copper powder remaining in the centrifuge 1 10 after dewatering is advanced to continuous belt 171 which conveys the powder through drier 1 12. Moisture is removed from the copper powder in drier 1 12 as indicated by directional arrow 173. The dried copper powder exits drier 1 and enters aggolmerate breaker 114 wherein aggolmerates that form during drying are broken. The powder is advanced from aggolmerate breaker 1 14 to screens 116 wherein the copper powder is separated into desired screen fractions and then advanced to storage hoppers 118, 120 and 122. Two screens and three storage hoppers are illustrated in Fig. 2, but those skilled in the art will recognize that any desired number of separation screens and storage hoppers can be used. In one embodiment, the use of separation screens is avoided due to the fact that the size of the copper powder produced by this method is relatively uniform.
The foregoing process for electrodepositing copper powder may be conducted on a continuous basis or a batch basis. In one embodiment, the operation of the electroforming cell is conducted on a continuous basis, and the operation of the centrifuge is conducted on a batch basis.
Sten (D) to Make Copper Foil In one embodiment, copper foil is formed during the electrodeposition step (D) of the inventive process. In this embodiment, a rotating cathode is used and the electrodeposited copper is removed from the cathode as a continuous thin web of foil as the cathode rotates. The foil may be collected in roll form. The rotating cathode may be in the form of a cylindrical mandrel. However, alternatively, the cathode may be in the form of a moving belt. Both of these designs are known in the art. The anode has a curved shape conforming to the curved shape of the cathode to provide a uniform gap between the anode and the cathode. This gap may be from about 0.3 to about 2 centimeters in thickness.
5 The velocity of the flow of the electrolyte solution through the gap between the anode and the cathode may be in the range of about 0.2 to about 5 meters per second, and in one embodiment about 1 to about 3 meters per second. The electrolyte solution may have a fee sulfuric acid concentration in the range of about 10 to about 200 grams per liter, and in one embodiment 10 about 80 to about 120 grams per liter. The temperature of the electrolyte solution in the electroforming cell may be in the range of about 25°C
to about 100°C, and in one embodiment about 40°C to about 70°C.
The copper ion concentration may be in the range of about 50 to about 150 grams per liter, and in one embodiment about 70 to about 130 grams per liter, and in one 15 embodiment about 90 to about 1 10 grams per liter. The current density may be in the range of about 100 to about 3000 amps per square foot, and in one embodiment about 500 to about 1800 amps per square foot.
The impurity level may be in the range of up to about 20 grams per liter, and in one embodiment in the range of up to about 10 grams per liter.
The 20 impurity may be one or more additional metals carried over from step (B) of the inventive process. The impurities may be organic or inorganic and include nitrates, phosphates, sulfides, and the like.
The free chloride ion concentration may be in the range of up to about 100 ppm, and in one embodiment up to about 50 ppm, and in one embodiment up to about 20 ppm, and in one embodiment up to about 10 ppm, and in one embodiment up to about 5 ppm, and in one embodiment about 0.05 to about 5 ppm, and in one embodiment about 0.05 to about 2 ppm, and in one embodiment about 0.05 to about 1 ppm. Chloride ions may be added as HCI, NaCI, KCI or other free chloride-containing species. In one embodiment, chloride ions are not added and any chloride ions that are present are impurities.

The electrolyte solution may contain one or more organic additives, the concentration of said organic additive being in the range of up to about ppm, and in one embodiment up to about 10 ppm, and in one embodiment up to about 5 ppm. In one embodiment the organic additive is an active sulfur-containing compound. The term "active-sulfur containing compound"
refers to compounds characterized generally as containing a bivalent sulfur atom both bonds of which are directly connected to a carbon atom together with one or more nitrogen atoms also directly connected to the carbon atom. In this group of compounds the double bond may in some cases exist or alternate between the sulfur or nitrogen atom and the carbon atom. Thiourea is a useful active sulfur-containing compound. The thioureas have the nucleus N H-i S=C
N H-Iso-thiocyanates having the grouping S = C = N- are useful. Thiosinamine and thiosemicarbazide are also useful. The active sulfur-containing compound should be soluble in the electrolyte solution and be compatible with the other constituents.
In one embodiment the organic additive is one or more gelatins.
The gelatins that are useful herein are heterogeneous mixtures of water-soluble proteins derived from collagen. Animal glue is a useful gelatin.
In one embodiment the organic additive is selected from the group consisting of molasses, guar gum, the polyalkylene glycols (e.g., polyethylene glycol, polypropylene glycol, polyisopropylene glycol, etc.), dithiothreitol, amino acids (e.g., proline, hydroxyproline, cysteine, etc.), acrylamide, sulfopropyl disulfide, tetraethylthiuram disulfide, benzyl chloride, epichlorohydrin, chlorohydroxylpropyl sulfonate, alkylene oxides (e.g., ethylene oxide, propylene oxide, etc.l, the sulfonium alkane sulfonates, thiocarbamoyldisulfide, or a mixture of two or more thereof.

In one embodiment, no organic additives are used.
In one embodiment, a continuous electrodeposition process for making copper foil is provided. A flow sheet illustrating this process is provided as Fig. 3. The apparatus used with this process includes an electroforming cell 200 that includes anode 202, cathode 204, vessel 206 and electrolyte solution 208. Anode 202 is submerged in electrolyte solution 208, and cathode 204 is partially submerged in electrolyte solution 208.
A voltage is applied between anode 202 and cathode 204: The electric current may be direct current or alternating current with a direct current bias. Copper ions in solution 208 gain electrons at the peripheral surface 204a of cathode 204 whereby metallic copper plates out in the form of a thin foil layer 210. Cathode 204 rotates continuously about its axis 204b during the process and foil layer 210 is continuously withdrawn from surface 204a as a continuous web which is formed into a roll 210a.
The process depletes the electrolyte solution of copper ions and, when used, organic additives. These ingredients are continuously replenished.
Spent electrolyte solution 208 is withdrawn through line 212 and recirculated through filter 214, vessel 216 and filter 218, and then is reintroduced into vessel 206 through line 220. Sulfuric acid may be advanced to vessel 216 through line 224. Copper from step (B) of the inventive process is introduced into vessel 216 through line 228.
Organic additives may be added to the recirculating solution in line 212 from a source 230 through line 232. Active sulfur-containing material may be added to the recirculating solution in line 220 through line 234 from a source 236.
The copper foil produced by the inventive method may be a high purity product. In one embodiment, the copper foil has a copper content of at least about 99.95% by weight, and in one embodiment it is at least about 99.995% by weight.
The ultimate tensile strength (UTS) for the copper foil at 23°C
may be in the range of about 35,000 psi to about 100,000 psi, and in one embodiment about 50,000 psi to about 70,000 psi, using Test Method 2.4.18 of IPC-TM-650. The UTS for these foils at 180 ° C may be in range of about 20,000 psi to about 35,000 psi, and in one embodiment about 21,000 psi to about 32,000 psi using the foregoing test method.
The elongation for these foils at 23°C may be about 2% to about 50% using Test Method 2.4.18 of IPC-TM-650. The elongation of these foils at 180°C may be about 4% to about 20%, and in one embodiment about 5%
to about 10% using the foregoing test method.
The copper foil may have matte-side raw foil roughnesses, Rtm, of about 1 to about 15 microns, and in one embodiment about 2 to about 10 microns. Rtm is the mean of the maximum peak-to-valley vertical extents from each of five consecutive sampling lengths, and can be measured using a Surftronic 3 profilometer marketed by Rank Taylor Hobson, Ltd., Leicester, England.
The Rtm for the shiny side of the foil may be less than about 6 microns, and in one embodiment less than about 5 microns, and in one embodiment in the range of about 2 to about 6 microns, and in one embodiment in the range of about 2 to about 5 microns.
The copper foil may have a weight in the range of about 1 /8 to about 14 ounces per square foot, and in one embodiment about 1 /4 to about 6 ounces per square foot, and in one embodiment about 1 /2 to about 2 ounces per square foot. In one embodiment, these foils have weights of about 1 /2, 1 or 2 ounces per square foot. A foil having a weight of 1 /2 ounce per square foot has a nominal thickness of 17 microns. A foil having a weight of 1 ounce per square foot has a nominal thickness of 35 microns. A foil having a weight of 2 ounces per square foot has a nominal thickness of 70 microns.
The term "untreated" is used herein to refer to a base foil that has not undergone subsequent treatment for the purpose of refining or enhancing the foil properties. The term "treated" is used herein to refer to a foil that has undergone such treatment. This treatment is entirely conventional and typically involves the use of various treating and rinsing solutions. The foils produced by the inventive process may be untreated or they may be treated.
In one embodiment, the base foil has at least one roughened layer of copper or copper oxide applied to at least one side of the foil.
In one embodiment, the base foil has at least one metallic or barrier layer applied to at least one side of the foil. The metal in this metallic layer is selected from the group consisting of indium, zinc, tin, nickel, cobalt, copper-zinc alloy and copper-tin alloy.
In one embodiment, the base foil has at least one metallic or stabilization layer applied to at least one side of the foil. The metal in this metallic layer is selected from the group consisting of tin, chromium, and chromium-zinc alloy.
In one embodiment, the base foil has at least one first metallic or barrier layer applied to at least one side of the foil, the metal in the first metallic layer being selected from the group consisting of indium, zinc, tin, nickel, cobalt, copper-zinc alloy and copper-tin alloy, and at least one second metallic or stabilization layer applied to the first metallic layer, the metal in the second metallic layer being selected from the group consisting of tin, chromium, and chromium-zinc alloy.
In one embodiment, the base foil has at least one roughened layer of copper or copper oxide applied to at least one side of the foil, at least one first metallic or barrier layer applied to the roughened layer, the metal in the first metallic layer being selected from the group consisting of indium, zinc, tin, nickel, cobalt, copper-zinc alloy and copper-tin alloy, and at least one second metallic or stabilization layer applied to the first metallic layer, the metal in the second metallic layer being selected from the group consisting of tin, chromium, and chromium-zinc alloy.
A silane coupling agent may be applied over the one or both sides of the foil or to one of the above-mentioned metallic treatment layers. The silane coupling agent may be represented by the formula R4_~SiX~
wherein R is a functionally substituted hydrocarbon group, the functional substituent of said functionally substituted hydrocarbon group being amino, 5 hydroxy, halo, mercapto, alkoxy, acyl, or epoxy; X is a hydrolyzable group, such as alkoxy (e.g., methoxy, ethoxy, etc.), or halogen (e.g., chlorine); and n is 1, 2 or 3, and preferably n is 3. The silane coupling agents represented by the above formula include halosilanes, aminoalkoxysilanes, aminophenylsilanes, phenylsilanes, heterocyclic silanes, N-heterocyclic silanes, acrylic silanes, 10 mercapto silanes, and mixture of two or more thereof.
Useful silane coupling agents include those selected from the group consisting of aminopropyltrimethoxy silane, tetramethoxy silane, tetraethoxy silane, bis(2-hydroxyethyl)-3-aminopropyltriethoxy silane, 3-(N-styrylmethyl-2-aminoethylamine) propyltrimethoxy silane, 3-glycidoxypropyltrimethoxy silane, 15 N-methylaminopropyltrimethoxy silane, 2-(2-aminoethyl-3-aminopropyl)trimethoxy silane, and N-phenylaminopropyltrimethoxy silane.
The coating of the foil surface with the silane coupling agent may be effected by applying the silane coupling agent alone to the surface of the foil.
However, it is generally preferred that coating be effected by applying the silane 20 coupling agent in a suitable medium to the foil surface. More specifically, the silane coupling agent can be applied to the foil surface in the form of a solution in water, a mixture of water and alcohol, or a suitable organic solvent, or as an aqueous emulsion of the silane coupling agent, or as an aqueous emulsion of a solution of the silane coupling agent in a suitable organic solvent.
Conventional 25 organic solvents may be used for the silane coupling agent and include, for example, alcohols, ethers, ketones, and mixtures of these with aliphatic or aromatic hydrocarbons or with amides such as N,N-dimethylformamide. Useful solvents are those having good wetting and drying properties and include, for example, water, ethanol, isopropanol, and methylethylketone. Aqueous emulsions of the silane coupling agent may be formed in conventional manner using conventional dispersants and surfactants, including non-ionic dispersants.

It may be convenient to contact the metal surface with an aqueous emulsion of the silane coupling agent. The concentration of the silane coupling agent in such solutions or emulsions can be up to about 100% by weight of the silane coupling agent, and in one embodiment is in the range of about 0.1 % to about 5% by weight, and in one embodiment about 0.3% to about 1 % by weight.
The process of coating with the silane coupling agent may be repeated, if desired, several times. The silane coupling agent may be applied to the foil surface using known application methods which include reverse roller coating, doctor blade coating, dipping, painting and spraying.
The application of the silane coupling agent to the foil surface may be effected at a temperature of about 15 ° C to about 45 ° C, and in one embodiment about 20°C to about 30°C. Following application of the silane coupling agent to the foil surface, the silane coupling agent may be heated to a temperature of about 60°C to about 170°C, and in one embodiment about 90°C to 150°C, for generally about 0.1 to about 5 minutes, and in one embodiment about 0.2 to about 2 minutes to enhance drying of the surface.
The dry film thickness of the silane coupling agent on the foil may be from about 0.002 to about 0.1 micron, and in one embodiment about 0.005 to about 0.02 microns.
The copper foil has a smooth or shiny (drum) side and a rough or matte (copper deposit growth front) side. These foils may be bonded to dielectric substrates to provide dimensional and structural stability thereto, and in this regard, it is preferred to bond the matte side of the electrodeposited foil to the substrate so that the shiny side of the foil faces outwardly from the laminate. Useful dielectric substrates may be prepared by impregnating woven glass reinforcement materials with partially cured resins, usually epoxy resins.
These dielectric substrates are sometimes referred to as prepregs.
In preparing the laminates, it is useful for both the prepreg material and the electrodeposited copper foil to be provided in the form of long webs of material rolled up in rolls. The rolled materials are drawn off the rolls and cut into rectangular sheets. The rectangular sheets are then laid-up or assembled in stacks of assemblages. Each assemblage may comprise a prepreg sheet with a sheet of foil on either side thereof, and in each instance, the matte side of the copper foil sheet is positioned adjacent the prepreg so that the shiny sides of the sheets of foil face outwardly on each side of the assemblage.
The assemblage may be subjected to conventional laminating temperatures and pressures between the plates of laminating presses to prepare laminates comprising sandwiches of a sheet of prepreg between sheets of copper foil.
The prepregs may consist of a woven glass reinforcement fabric impregnated with a partially cured two-stage resin. By application of heat and pressure, the matte side of the copper foil is pressed tightly against the prepreg and the temperature to which the assemblage is subjected activates the resin to cause curing, that is crosslinking of the resin and thus tight bonding of the foil to the prepreg dielectric substrate. Generally speaking, the laminating operation will involve pressures in the range of from about 250 to about 750 psi, temperatures in the range of from about 175°C to 235°C and a laminating cycle of from about 40 minutes to about 2 hours. The finished laminate may then be utilized to prepare printed circuit boards (PCB1.
A number of manufacturing methods are available for preparing PCBs from laminates. Additionally, there is a myriad of possible end use applications including radios, televisions, computers, etc., for the PCB's.
These methods and end uses are known in the art.
While the invention has been explained in relation to its preferred embodiments, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification.
Therefore, it is to be understood that the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims.

Claims (32)

Claims

1. A process for recovering copper from a high acid mixed metal solution, said high acid mixed metal solution having a pH of about 0.5 or less and comprising copper ions, ions of at least one additional metal and sulfuric acid, said process comprising:
(A) separating said high acid mixed metal solution into a first fraction comprising copper ions and ions of said at least one additional metal, and a second fraction comprising said sulfuric acid;
(B) separating said copper ions from said first fraction;
(C) forming an electrolyte solution comprising said copper ions from step (B); and (D) electrodepositing copper from said electrolyte solution.

2. The process of claim 1 wherein said high acid mixed metal solution has a copper ion concentration in the range of about 1 to about 300 grams per liter, an additional metal ion concentration in the range of about 1 to about 100 grams per liter, and a sulfuric acid concentration of about 50 to about 400 grams per liter.

3. The process of claim 1, wherein said high acid mixed metal solution is a copper/nickel matte leaching solution, a bleed solution from an electrolytic copper refinery, or spent etchant from the processing of circuit boards.

4. The process of claim 1, wherein said at least one additional metal is antimony, arsenic, bismuth, cobalt, iron, nickel, lead, tin, zinc, or a mixture of two or more thereof.

5. The process of claim 1, wherein during step (A) said high acid mixed metal solution is heated to a temperature in the range of about 75°C
to about 95°C to evaporate water and then cooled to a temperature in the range of about 0°C to about 30°C to form a precipitate, said precipitate comprising salts of copper and said at least one additional metal.

6. The process of claim 1, wherein during step (A) acid from said mixed metal solution is sorbed by a polymeric resin material, and salts of copper and said at least one additional metal are not sorbed by said polymeric resin material.

7. The process of claim 1, wherein during step (B) said first fraction from step (A) is dissolved in water to form an aqueous solution containing dissolved salts of copper and said at least one additional metal, and the pH of said aqueous solution is increased sufficiently to precipitate said salts of said at least one additional metal, said copper salt remaining in solution.

8. The process of claim 1, wherein during step (B) said first fraction from step (A) is dissolved in water to form an aqueous solution containing dissolved salts of copper and said at least one additional metal, said aqueous solution contacting a copper selective ion exchange material for an effective period of time to transfer copper ions from said aqueous solution to said copper selective ion exchange material.

9. The process of claim 1 wherein the electrolyte solution formed during step (C) has a copper ion concentration of about 1 to about 200 grams per liter, and additional metal ion concentration of up to about 1000 parts per million, and a sulfuric acid concentration of about 10 to about 300 grams per liter.

10. The process of claim 1, wherein during step (D) said copper is electrodeposited as copper powder.

11. The process of claim 10, wherein during step (D) the concentration of copper ions in said electrolyte solution is in the range of about 1 to about 60 grams per liter, and the free sulfuric acid concentration in said electrolyte is in the range of about 50 to about 300 grams per liter.

12. The process of claim 10 wherein during step (D) the temperatures of said electrolyte solution is in the range of about 15°C
to about 65°C.

13. The process of claim 10 wherein during step (D) said electrodepositing is conducted in an electroforming cell equipped with an anode and a cathode immersed in said electrolyte solution, the flow rate of electrolyte solution through said electroforming cell being in the range of about 0.01 to about 0.3 gallons per minute per square foot of the immersed surface area of said cathode.

14. The process of claim 10 wherein during step (D) said electrodepositing is conducted in an electroforming cell equipped with an anode and a cathode, said anode being a dimensionally stable anode, said cathode being comprised of titanium or stainless steel.

15. The process of claim 10 wherein during step (D) said electrodepositing is conducted in an electroforming cell equipped with an anode and a cathode and an electric current is used to apply an effective amount of voltage across said anode and said cathode to deposit said copper powder on said cathode, the current density being in the range of about 20 to about 300 amps per square foot.

16. The process of claim 10 wherein during step (D) said electrodepositing is conducted in an electroforming cell equipped with an anode and a cathode, the spacing between said anode and said cathode being from about 1 to about 4 inches.

17. The process of claim 1, wherein during step (D) said copper is electrodeposited as copper foil.

18. The process of claim 17 wherein during step (D) said electrolyte solution flows between an anode and a cathode, an effective amount of voltage is applied across said anode and said cathode to deposit copper on said cathode, the current density being in the range of about 100 to about amps per square foot, and copper foil is removed from said cathode.

19. The process of claim 17 wherein during step (D) said electrolyte solution contains at least one organic additive.

20. The process of claim 17 wherein during step (D) said electrolyte solution contains no organic additive.

21. The process of claim 17 wherein during step (D) said electrolyte solution has a copper ion concentration in the range of about 50 to about 150 grams per liter and a free sulfuric acid concentration in the range of about 10 to about 200 grams per liter.

22. The process of claim 18 wherein the current density during step (D) is from about 500 to about 1800 amps per square foot.

23. The process of claim 17 wherein the temperature of said electrolyte solution during step (D) is about 25°C to about 100°C.

24. The process of claim 18 wherein the flow velocity of electrolyte solution between said anode and said cathode during step (D) is from about 0.2 to about 5 meters per second.

25. The process of claim 17 with the step of applying to at least one side of said foil at least one roughened layer of copper or copper oxide.

26. The process of claim 17 with the step of applying to at least one side of said foil at least one metallic layer, the metal in said metallic layer being selected from the group consisting of indium, zinc, tin, nickel, cobalt, copper-zinc alloy and copper-tin alloy.

27. The process of claim 17 with the step of applying to at least one side of said foil at least one metallic layer, the metal in said metallic layer being selected from the group consisting of tin, chromium, and chromium-zinc alloy.

28. The process of claim 17 with the steps of applying to at least one side of said foil at least one first metallic layer, the metal in said first metallic layer being selected from the group consisting of indium, zinc, tin, nickel, cobalt, copper-zinc alloy and copper-tin alloy, then applying to said first metallic layer at least one second metallic layer, the metal in said second metallic layer being selected from the group consisting of tin, chromium, and chromium-zinc alloy.

29. The process of claim 17 with the steps of applying to at least one side of said foil at least one roughened layer of copper or copper oxide, then applying to said roughened layer at least one first metallic layer, the metal in said first metallic layer being selected from the group consisting of indium, zinc, tin, nickel, cobalt, copper-zinc alloy and copper-tin alloy, then applying to said first metallic layer at least one second metallic layer, the metal in said second metallic layer being selected from the group consisting of tin, chromium, and chromium-zinc alloy.

30. The process of claim 17 with step of applying a silane coupling agent to at least one side of said foil.

31. A process for recovering copper from a high acid mixed metal solution, said high acid mixed metal solution having a pH of about 0.5 or less and comprising copper ions, ions of at least one additional metal and sulfuric acid, said process comprising:
(A) separating said high acid mixed metal solution into a first fraction comprising copper ions and said ions of at least one additional metal, and a second fraction comprising said sulfuric acid;
(B) separating said copper ions from said first fraction;
(C) forming an electrolyte solution comprising said copper ions from step (B); and (D) electrodepositing copper powder from said electrolyte solution.

32. A process for recovering copper from a high acid mixed metal solution, said high acid mixed metal solution having a pH of about 0.5 or less and comprising copper ions, ions of at least one additional metal and sulfuric acid, said process comprising:
(A) separating said high acid mixed metal solution into a first fraction comprising copper ions and ions of said at least one additional metal, and a second fraction comprising said sulfuric acid;
(B) separating said copper ions from said first fraction;
(C) forming an electrolyte solution comprising said copper ions from step (B); and (D) electrodepositing copper foil from said electrolyte solution.