JP2014129583A - Method for recovering metal or alloy from high-purity metal or alloy scrap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for recovering a metal or alloy at a purity which is capable of being used as a production raw material in the original utilization, without lowering the purity, from a high-purity metal or alloy scrap, at a low cost.SOLUTION: Provided is a method for recovering a metal or alloy from a high-purity metal or alloy scrap, containing the step of: subjecting a high-purity metal or alloy scrap to electrolysis with an electrolyte solution containing an alcohol amine.

Description

  The present invention relates to a method for recovering a metal or alloy from high-purity metal or alloy scrap.

  As a metal recovery method, usually, a process of pulverizing a scrap containing the metal and then dissolving with alkali is used. However, for example, when recovering the metal from scrap containing a metal that is very hard and has high chemical resistance, the application of such a normal process is very difficult. Therefore, it is a regular method to dissolve and recover these metals by oxidizing them with a strong treatment such as an alkali molten salt.

  On the other hand, for example, molybdenum used targets and mill ends are originally of high purity, so using molten salt treatment or pulverization, which is a general treatment as described above, greatly reduces the purity. . Therefore, in order to purify the metal, the treatment process tends to be complicated, such as requiring multistage purification or ion exchange treatment.

  As a technique for dissolving the metal, there is electrolysis. For example, in Patent Document 1, as an electrolytic processing liquid composition intended to carry out either an electrolytic etching process or an electrolytic oxide film removal process, Basically, among (1) water-soluble electrolyte, (2) polarization improver, and (3) corrosion inhibitor (inhibitor), the water-soluble electrolyte of (1) is used as a basis, and (2) to (3) By using any one or a combination of two or more of the above, it is possible to perform electrolysis while suppressing the growth of a viscous liquid formed of a metal ion electrolyzed and an electrolyte component in the vicinity of the anode surface and a viscous liquid layer. An electrolytic etching treatment method is disclosed. (1) As a water-soluble electrolyte, one or more selected from hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid or their ammonium, potassium, sodium salt, potassium hydroxide, (2) Polarization As an improver, one or more selected from aminocarboxylic acids and salts thereof, ethanolamines, carboxylic acids or salts thereof, and (3) dehydrated cyclized ethanol derivatives as corrosion inhibitors (inhibitors) It is disclosed that one or two or more selected from amine compounds containing nitrogen, nitrogen-containing heterocyclized bases, and thiourea derivatives are used. And according to this, it describes that the electrolytic solution composition which performs these electrolytic processing very effectively can be provided when implementing the electrolytic processing including electrolytic etching and electrolytic oxide film removal.

  Patent Document 2 discloses that 0.1% by weight or more of phosphoric acid, citric acid, tartaric acid, oxalic acid, malic acid, acetic acid, gluconic acid, glycolic acid, succinic acid, etc. 0.1% by weight or more of triethanolamine, diethanolamine and monoethanolamine in one or more aqueous solutions of the group consisting of and sulfuric acid, and each salt group of these acids such as sodium, potassium and ammonium An electrolytic solution used in an electrolytic polishing method for stainless steel, characterized in that one or more of them are blended is disclosed. And according to this, in the electrolytic polishing method for the stainless steel surface, it can be used with alternating current, direct current and AC / DC superposition, and electrolysis that improves corrosion resistance performance not only in austenitic stainless steel but also in martensitic and ferritic stainless steel. It is described that a liquid can be provided.

  Patent Document 3 discloses a method for electrolytic polishing a surface of a metal selected from iron, tungsten, light metals, and alloys of these metals using an electrolytic solution, and the electrolytic solution includes methanesulfonic acid and At least one alcohol selected from the group consisting of an aliphatic diol represented by the general formula CnH2n (OH) 2, n = 2 to 6 and an alicyclic alcohol represented by the general formula CmH2m-1OH, m = 5-8 An electrolytic polishing method comprising a compound is disclosed. And according to this, it is described that it is possible to provide a substantially harmless method for work safety and environmental protection suitable for electropolishing the surfaces of iron, tungsten, light metals and their alloys. Has been.

Furthermore, Patent Document 4 discloses an electrolytic elution method for eluting platinum by electrolyzing platinum in an electrolytic solution as an anode, wherein the electrolytic solution is a hydrochloric acid solution of 8 to 11.5 N, and electrolytic conditions As a method, a method of eluting the platinum electrode by applying a current having a liquid temperature of 60 to 80 ° C. and a current density of 60 to 100 A / dm ² is disclosed. According to this, it is described that a method of efficiently dissolving platinum that is chemically stable and not easily dissolved by an electrolytic method can be provided.

JP-A-8-49100 JP 2007-277682 A JP 2008-121118 A JP 2011-131282 A

  As described above, a technique for dissolving various metals or alloys by an electrolytic method is known, but recovery processing using molten salt treatment or pulverization, which is a general treatment as described above, is a metal or alloy. In order to make the said metal or alloy highly purified, multistage refinement | purification, an ion exchange process, etc. are needed, and a process process becomes complicated.

  Therefore, the present invention provides a method for recovering metals and alloys with a purity such that scraps made of high-purity metals or alloys can be used as a raw material for production of the original application without reducing the purity at a low cost. This is the issue.

The present inventor has intensively studied in order to solve the above problems, and has focused attention on an electrolytic solution using alcohol amine. Alcoholamine does not contain impurities such as Na, K, Fe and S, has a relatively high boiling point, and an aqueous solution containing several percent is safe. Furthermore, since the voltage resistance is high and stable, and the pH dependency is low, it is easy to control during electrolysis, and replenishment by volatilization such as ammonia is not necessary, so that the running cost can be suppressed as a result. In this way, by using an electrolytic solution containing alcohol amine, scraps made of high-purity metals or alloys can be recovered with such purity that it can be used as a raw material for production of the original application without reducing the purity. I found.
In the inventions related to the electrolytic solutions of Patent Documents 2, 3, and 4, amine is used for the electrolytic solution. However, in Patent Document 2, the electrolyte contains an acid and sulfuric acid that act non-oxidatively on stainless steel such as phosphoric acid, citric acid, tartaric acid, oxalic acid, malic acid, acetic acid, gluconic acid, glycolic acid, and succinic acid. As well as one or two or more aqueous solutions of each of the groups of these salts, such as sodium, potassium, ammonium, etc. of these acids, which are different in configuration from the present invention. Further, Patent Document 3 contains methanesulfonic acid as an essential component, which is disadvantageous in that the structure is different from that of the present invention, and methanesulfonic acid is strongly acidic and very expensive. Moreover, in patent document 4, hydrochloric acid which is a strong acid is contained in electrolyte solution, and a structure differs from this invention.

  The present invention completed on the basis of the above knowledge is, in one aspect, a high-purity metal or alloy including a step of electrolyzing scrap made of a high-purity metal or alloy using an electrolyte containing alcohol amine. A method for recovering metals or alloys from scrap.

  In one embodiment of the method for recovering a metal or alloy from scrap of high purity metal or alloy according to the present invention, the alcohol amine is monoethanolamine and / or triethanolamine.

  In another embodiment of the method for recovering metal or alloy from scrap of high purity metal or alloy according to the present invention, the concentration of alcoholamine in the electrolyte is 1 to 40 mass%.

  In another embodiment of the method for recovering a metal or alloy from high-purity metal or alloy scrap according to the present invention, electrolysis is performed by adjusting the temperature of the electrolytic solution to 50 ° C. or higher.

  In still another embodiment of the method for recovering a metal or alloy from scrap of high purity metal or alloy according to the present invention, the pH of the electrolyte is 9 or more.

In yet another embodiment of the method for recovering a metal or alloy from high-purity metal or alloy scrap according to the present invention, the set voltage in the electrolysis is 30 V or less, and the set current density is 500 A / dm ² or less. is there.

  In yet another embodiment, the method for recovering a metal or alloy from a high-purity metal or alloy scrap according to the present invention is the production of the original use without reducing the purity from the high-purity metal or alloy scrap. Metals and alloys are recovered with the purity used as raw material.

  In yet another embodiment of the method for recovering a metal or alloy from high-purity metal or alloy scrap according to the present invention, the composition of the scrap consisting of the high-purity metal or alloy and the electrolyte containing the alcohol amine are used. The composition of the metals and alloys obtained by electrolysis used is the same.

According to the present invention, there is provided a method for recovering a metal and an alloy with such purity that scraps made of a high-purity metal or alloy can be used as a raw material for production of the original application without reducing the purity at a low cost. be able to.
More specifically:
(1) By not containing impurities such as Na, K, Fe and S in the treatment reaction system, the metal or alloy can be recovered with high purity without lowering the purity.
(2) A quality metal or alloy having a purity of 2N or more (99% or more) can be obtained from recycled materials or the like (in the case of an alloy, the sum of the constituent elements of the alloy).
(3) Since the electrolytic solution has a high withstand voltage and is stable and has a low pH dependency, it is easy to control during electrolysis and does not require replenishment by volatilization such as ammonia. it can.

It is a schematic diagram of an example of the electrolytic cell shown by embodiment of this invention. It is a figure which shows the relationship between electrolyte temperature and the dissolution rate of the said metal when electrolyzing the scrap of a high purity metal using the electrolyte solution which concerns on this invention, and the conventional electrolyte solution. It is a figure which shows the relationship between the constant voltage in electrolysis, and current efficiency.

  Hereinafter, embodiments of a method for recovering a metal or alloy from scrap of high-purity metal or alloy according to the present invention will be described in detail.

In the present invention, scraps of high-purity metals or alloys include scraps of sputtering target materials used for semiconductors and electronic parts, liquid crystal displays, tool coatings, glass coatings, optical disks, hard disks, solar cells, cathode materials for lithium ion batteries, and the like. It is done. For this reason, the metal or alloy contained in these constituent materials with high purity is the metal or alloy to be collected according to the present invention. Specific metal or alloy element types are listed below along with various applications:
, Semiconductor and electronic components: Ag, Al, Au, AuAs , AuSb, AuSi, AuSn, Al 2 O 3, Cr, Cu, CuCr, CrNiAl, CrSi, GeS 2, Hf, Ir, Mo, Ni, NiV, OsRu, Pd, Pt, PtNi, Rh, Ru, Si, Ta, TaAl, Ti, WTi, WTi, etc. ・ Liquid crystal display: Ag, Ag alloy, Al, AlNd, Cr, InSn, ITO, Mo, MoW, Si, SiO ₂ , Ta, Ti, W, ZnAl, ZAO (ZnO + Al ₂ O ₃ ), etc. Tool coating: Cr, CrAl, Ti, TiAl, etc. Glass coating: Ag, Ag alloy, Al, Bi, Cr, InSn, ITO, Nb , Nb ₂ O ₅ , NiCr, Si, SiO ₂ , Sn, Ta ₂ O ₅ , Ti, W, ZAO (ZnO + Al ₂ O ₃ ), Zn, etc. Optical disc: Al ₂ O ₃ , C, Co alloy, Cr , Fe alloy, Ta, Tb alloy, Te alloy, Pt, Pt alloy etc. Hard disk: Al ₂ O ₃ , C, CoCr, CoCrTa, CoCrPt, Cr, Cr alloy, Cr oxide, MgO, Mo, NiAl, NiSi, SiC, Ta, Ta ₂ O ₅ , Ti oxide, V, W, etc. Solar cells: Ag, Al, CIG (Cu + In + Ga), CuGa, ITO, Mo, Ni / NiV, Sn, ZAO (ZnO + Al ₂ O ₃ ) ・ Lithium-ion battery cathode materials: LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , Li (CoxNiyMnz) O ₂ as cathode materials [X + y + z = 1] etc., Ni, Co, Mn etc. as metal, NiCo etc. as alloy

  In the present invention, “high purity” means a metal or alloy having a purity of 2N or more (99.99% or more) (in the case of an alloy, the sum of the constituent elements of the alloy).

  In the method for recovering a metal or alloy from scrap of high-purity metal or alloy according to the present invention, first, a raw material mixture containing the high-purity metal or alloy to be treated is prepared. Examples of the raw material mixture include so-called recycled materials obtained by pulverizing high-purity metal or alloy scrap.

Next, an electrolytic cell including an anode and a cathode and an electrolytic solution is prepared, and the raw material mixture containing a high-purity metal or alloy is used for electrolysis.
Although an electrolytic cell is not specifically limited, For example, the structure shown in FIG. 1 may be sufficient. FIG. 1 uses a titanium basket as an anode, and a raw material mixture containing a high-purity metal or alloy is provided in the titanium basket. Titanium baskets are preferred in that they are stable under high voltage, high current and high temperature electrolytic treatment conditions as in the present invention.

  The electrolytic solution contains alcohol amine. Examples of the alcohol amine include triethanolamine, diethanolamine, monoethanolamine, aminopropanol, and methylethanolamine. In particular, monoethanolamine and triethanolamine are preferable in that they are inexpensive.

  The concentration of alcohol amine in the electrolytic solution is preferably 1 to 40 mass%. If the concentration of alcoholamine in the electrolytic solution is less than 1 mass%, the conductivity becomes too low and electrolysis becomes unstable. If the concentration of alcoholamine in the electrolytic solution exceeds 40 mass%, the solubility in water may be exceeded depending on the type of the electrolytic solution, and the concentration becomes higher than necessary, which is disadvantageous in terms of cost. The concentration of alcoholamine in the electrolytic solution is more preferably 2 to 10 mass%.

  The temperature of the electrolytic solution at the time of electrolysis may be room temperature, but higher temperature is better, and it is particularly preferable to adjust to 50 ° C. or higher. This is because the conductivity of the electrolytic solution increases at higher temperatures. Here, FIG. 2 shows the electrolytic solution temperature and the dissolution rate of tungsten when electrolyzing a tungsten (W) scrap contained at a purity of 99.99% using the electrolytic solution according to the present invention and the conventional electrolytic solution. Shows the relationship. In the figure, the graph of the result of electrolysis in the electrolytic cell using the electrolytic solution according to the present invention is described as the present PAT bath, and the graph of the result of electrolysis in the electrolytic cell with the conventional electrolytic solution is shown as the conventional bath. It is described. In this PAT bath, a 10% aqueous solution of monoethanolamine is used as an electrolytic solution, and electrolysis is performed at a constant voltage of 10V. On the other hand, in a conventional bath, ammonium nitrate and ammonia are used as an electrolytic solution, and electrolysis is performed at a constant voltage of 10V. The dissolution rate of tungsten is plotted as a relative value when the value of the electrolytic solution at 25 ° C. is 1.0. As shown in this figure, it is difficult to raise the temperature of the conventional bath to a temperature higher than that since the ammonia volatilization becomes intense when the temperature of the electrolytic solution is 45 ° C. or higher. On the other hand, since this PAT bath is composed of a high boiling point solvent, it can be electrolyzed without any problem up to the water evaporation temperature range or lower, and as a result, the dissolution rate increases at 50 ° C. or higher, and the productivity increases.

  The pH of the electrolytic solution is adjusted so that the electrolytic solution is weakly alkaline, and is preferably 9 or more, more preferably 10 or more. When the pH is less than 9, ions relating to the produced high-purity metal or alloy cannot be dissolved, and a compound is formed and deposited, and as a result, electrolytic dissolution may be hindered.

Alcoholamines used in the electrolyte have high withstand voltage and current withstand density, and it is preferable for the productivity that the set voltage and set current density in electrolysis are higher. Therefore, it is preferable that the set voltage is 30 V or less and the set current density is 500 A / dm ² or less because it is practical. For reference, FIG. 3 shows the relationship between constant voltage and current efficiency in electrolysis. As shown in FIG. 3, when the voltage / current density is low, the processing amount (production amount) per time is small.

  A high purity metal or alloy is dissolved in an electrolytic solution by electrolysis, and then neutralized with hydrochloric acid, nitric acid or the like, and the high purity metal or alloy is taken out as a hydroxide. In this case, the quality of the high-purity metal or alloy is already as high as 2N or higher in the hydroxide state.

  Next, the obtained high-purity metal or alloy hydroxide is concentrated to form a metalate compound, and is recovered as a high-purity metal oxide, simple metal or alloy by heating and reducing as necessary. . At this time, the metal and alloy can be recovered with the purity used as the raw material for the original application.

The method for recovering a high-purity metal or alloy according to the present invention can recover a high-purity metal or alloy at an inexpensive cost by electrolysis using an electrolytic solution containing an alcoholamine as described above. it can. In particular:
(1) By not containing impurities such as Na, K, Fe and S in the treatment reaction system, the metal or alloy can be recovered with high purity without lowering the purity. Moreover, the composition of the scrap made of a high-purity metal or alloy and the composition of the metal and alloy obtained by electrolysis using an electrolytic solution containing an alcohol amine can be easily made the same.
(2) A quality metal or alloy having a purity of 2N or more (99.99% or more) can be obtained from recycled materials or the like (in the case of an alloy, the sum of the constituent elements of the alloy).
(3) Since the electrolytic solution has a high withstand voltage and is stable and has a low pH dependency, it is easy to control during electrolysis and does not require replenishment by volatilization such as ammonia. it can.
Here, the reason why the withstand voltage and stability of the electrolyte solution of alcohol amine is high and stable is unknown, but it is probably because the dissolved metal or alloy is stabilized by coordination with alcohol amine. It is thought that there is.

  Examples of the present invention will be described below, but the examples are for illustrative purposes and are not intended to limit the invention.

Example 1
As the anode of the electrolytic cell, 5.0 kg of a target piece of molybdenum (purity 99.99%: 4N) was used.
A titanium plate was used as the cathode of the electrolytic cell.
As an electrolytic solution for the electrolytic bath, pure water was added to monoethanolamine to prepare 20 L of a 11.0 pH electrolytic solution having a monoethanolamine concentration of 5 mass%.
Using these, the set voltage was 10 V, the current density was 5 A / dm ² , the temperature was adjusted to 60 ° C. at a constant current of 100 A, and electrolysis was performed for 10 hours.
As a result, high purity molybdenum of 4N or higher was recovered. The amount of molybdenum dissolved was 0.6 kg, and the current efficiency was almost 100%. Thus, high purity metal could be efficiently recovered by a simple manufacturing process without degrading purity from high purity metal scrap.

(Example 2)
As an anode of the electrolytic cell, a small piece of MoSi ₂ alloy (purity 99.99%: 4N) scrap 3.0 kg was used.
A titanium plate was used as the cathode of the electrolytic cell.
As an electrolytic solution for the electrolytic cell, 10 L of an electrolytic solution having a pH of 11.0 and a monoethanolamine concentration of 10 mass% was prepared by adding pure water to monoethanolamine.
Using these, the set voltage was 10 V, the current density was 50 A / dm ² , the temperature was adjusted to 60 ° C. at a constant current of 500 A, and electrolysis was performed for 2 hours.
As a result, the purity of molybdenum excluding silicon was 99.99%: 4N. The molybdenum dissolution amount was 0.59 kg, and the current efficiency was almost 100%. Thus, high purity metal could be efficiently recovered by a simple manufacturing process without degrading purity from high purity metal scrap.

(Comparative Example 1)
As the anode of the electrolytic cell, a tungsten recycling material (purity 99.999%: 5N) in which 5 kg of irregular shaped end materials were put in a titanium basket was used.
A titanium plate was used as the cathode of the electrolytic cell.
As an electrolytic solution for the electrolytic bath, pure water was added to ammonium nitrate and aqueous ammonia, and 10 L of an electrolytic solution with a pH of 10.6 having an ammonium nitrate concentration of 10 mass% and an ammonia concentration of 5 mass% was prepared.
Using these, the set voltage was 5 V, the current density was 5 A / dm ² , the temperature was adjusted to 70 ° C. at a constant current of 50 A, and electrolysis was performed for 10 hours.
As a result, the purity of the collected tungsten was 99.999% because there was no impurity in the electrolyte, but the tungsten dissolution amount was 0.5 kg and the current efficiency was almost 90%, which was lower than that of the example. . In addition, since the ammonia component volatilizes during electrolysis, it is necessary to replenish the electrolyte solution with ammonia water as needed, which is very time-consuming and requires a large amount of ammonia supply. It was disadvantageous in terms of costs and costs.
In Comparative Example 1, a test using caustic soda (NaOH) as an electrolytic solution and a test using sodium sulfite (Na ₂ SO ₃ ) were performed. However, Na and S each decreased the purity. The purity of the collected tungsten was 99.95%.

Claims (8)

  A method for recovering a metal or alloy from a scrap of high-purity metal or alloy, comprising a step of electrolyzing a scrap made of high-purity metal or alloy with an electrolyte containing alcohol amine.   The method for recovering a metal or alloy from high-purity metal or alloy scrap according to claim 1, wherein the alcohol amine is monoethanolamine and / or triethanolamine.   The method for recovering a metal or alloy from scrap of high-purity metal or alloy according to claim 1 or 2, wherein the concentration of alcoholamine in the electrolytic solution is 1 to 40 mass%.   The method for recovering a metal or alloy from high-purity metal or alloy scrap according to any one of claims 1 to 3, wherein electrolysis is performed by adjusting the temperature of the electrolytic solution to 50 ° C or higher.   The method for recovering a metal or alloy from high-purity metal or alloy scrap according to any one of claims 1 to 4, wherein the electrolyte has a pH of 9 or more. The method for recovering a metal or alloy from high-purity metal or alloy scrap according to any one of claims 1 to 5, wherein a set voltage in the electrolysis is 30 V or less and a set current density is 500 A / dm ² or less.   The high-purity metal or alloy according to any one of claims 1 to 6, wherein the metal and the alloy are recovered from the scrap made of the high-purity metal or alloy at a purity used as a raw material for production of the original application without reducing the purity. To recover metal or alloy from scrap   The composition of the scrap made of the high-purity metal or alloy and the composition of the metal and alloy obtained by electrolysis using the electrolytic solution containing the alcohol amine are the same. Of recovering metal or alloy from high-purity metal or alloy scrap.