WO2022138982A1 - Method for recovering platinum-group metal - Google Patents

Method for recovering platinum-group metal Download PDF

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Publication number
WO2022138982A1
WO2022138982A1 PCT/JP2021/048591 JP2021048591W WO2022138982A1 WO 2022138982 A1 WO2022138982 A1 WO 2022138982A1 JP 2021048591 W JP2021048591 W JP 2021048591W WO 2022138982 A1 WO2022138982 A1 WO 2022138982A1
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Prior art keywords
platinum group
group metal
laminate
base material
voltage
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PCT/JP2021/048591
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French (fr)
Japanese (ja)
Inventor
和哉 島田
雅仁 速水
至人 小池
俊彦 坂田
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パナソニックＩｐマネジメント株式会社
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Priority to JP2022532674A priority Critical patent/JP7126185B1/en
Publication of WO2022138982A1 publication Critical patent/WO2022138982A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B11/00—Obtaining noble metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to a method for recovering a platinum group metal from a laminate in which a platinum group metal or an oxide layer thereof is formed on the metal.
  • the present invention relates to a method of recovering a platinum group metal from a metal electrode base material on which a platinum group metal layer is formed by chemical treatment or chemical electrolysis.
  • the surface of the metal base material is roughened in order to increase the adhesive force of the platinum group metal layer. Then, on the surface of the platinum group metal layer, the current density generated between the platinum group metal layer and the counter electrode is different depending on the location, and the platinum group metal layer is cracked and deteriorates over time.
  • the deteriorated electrode is discarded, but it is desired to reuse it because both the metal base material and the platinum group metal are rare resources. However, these metals are extremely stable and cannot be separated and recovered easily.
  • Patent Document 1 discloses a method of removing a platinum group metal by finely cutting an electrode, peeling off the platinum group metal layer by polishing, and then acid cleaning.
  • an anode and a cathode made of a metal substrate having a gold or platinum group metal coating are immersed in an electrolytic solution containing fluoride as a main component, and an anode electrolytic treatment is performed by passing a current through these electrodes.
  • an anode electrolytic treatment is performed by passing a current through these electrodes.
  • Japanese Unexamined Patent Publication No. 2001-303141 Japanese Patent No. 4450945 Japanese Unexamined Patent Publication No. 7-109594: Japanese Patent No. 2630702
  • the layer of platinum group metal such as iridium and ruthenium on a hard metal substrate such as titanium, zirconium, and niob is coated with a solution containing platinum group metal ions (for example, a platinum group chlorocomplex solution) on the surface of the substrate. , Obtained by firing. It is manufactured by repeating coating and firing many times in order to adjust the thickness of the layer to a predetermined value. It is not easy to peel off the platinum group metal layer once formed on the metal substrate.
  • the metal base material after recovery of the platinum group is desired to be reused, but the metal base material cannot be reused if the treated metal is finely cut as in Patent Document 1.
  • reuse means to include a recoat that forms a platinum group metal layer again on the metal substrate.
  • the timing at which the platinum group metal is peeled off and the metal base material appears can be determined by monitoring the time when the voltage rises sharply when the anodic electrolysis treatment is performed with a constant current.
  • the change in the voltage value when the platinum group metal is peeled off may be very steep. There was a problem that it was difficult to understand when to stop processing.
  • the platinum group metal can be sufficiently recovered, but the metal base material becomes thin and thin, and the metal base material can be reused. It disappears.
  • the metal base material When targeting an electrode on which a platinum group metal layer is formed on only one side, the metal base material is exposed on the back side, and when chemical peel is applied, the base material on the back side is significantly dissolved. As a result, the metal base material cannot be reused (recoated), and the value of the metal base material after the peeling treatment is impaired.
  • the present invention is equivalent in view of the above problems, and provides a method for effectively recovering not only a platinum group metal from a laminate but also a metal base material.
  • the method for recovering a platinum group metal is as follows.
  • the method for recovering a platinum group metal is as follows.
  • the platinum group metal layer is peeled off by simply immersing the laminate in which the platinum group metal layer is formed on the metal substrate in an aqueous solution containing fluorine, so that the hardness is high.
  • the highly chemically stable platinum group metal layer can be easily peeled off.
  • the metal substrate violently generates hydrogen when it comes into contact with fluorine, but by mixing hydrogen hydrogen into an aqueous solution containing fluorine, the generation of hydrogen can be significantly suppressed, and the platinum group can be safely used. Metal can be recovered.
  • the laminate is immersed in an aqueous solution containing fluorine (hereinafter referred to as "electrolytic solution"), and a positive voltage is applied.
  • electrolytic solution an aqueous solution containing fluorine
  • the platinum group metal layer can be peeled off (lifted off) from the substrate dissolution site and recovered.
  • the reaction (depot) that protects the base material and the base material are melted. Since the reaction (etching) occurs at the same time, the metal substrate after the platinum group is peeled off can suppress the dissolution as much as possible and can be recovered in a recoatable state.
  • the recovery method of the present invention even if the film thickness of the platinum group metal varies, only the platinum group metal can be effectively recovered, and the surface of the metal substrate is before the platinum group metal is laminated.
  • the metal substrate can be recovered in the same state as the original state (roughened state).
  • the first half of the peeling process is processed with a high voltage (which may be constant voltage or constant current), and the second half is processed with a constant voltage, which is shorter than the case of processing only with a constant voltage. Can be done.
  • the platinum group metal can be efficiently peeled off without melting the base material too much. can.
  • the laminated body by immersing the laminated body in a pair in an electrolytic solution and applying an alternating current to these, the laminated body alternately becomes an anode, and the platinum group metal can be recovered more effectively.
  • the method for recovering a platinum group metal according to the present invention uses a laminate in which a layer of a platinum group metal is formed on a metal substrate as a recovery raw material.
  • a metal including an alloy
  • a high hardness containing elements of Group 4 and Group 5 such as titanium (Ti), zirconium (Zr), and niobium (Nb) is used.
  • the platinum group metal metals such as platinum (Pt), gold (Au), iridium (Ir) and ruthenium (Ru) are used. Therefore, the laminate in the present invention is a laminate in which platinum group metals are formed in layers or islands on these metal substrates.
  • Such a laminate is often used as an anode electrode for salt water electrolysis, electrolysis water production, chemical conversion treatment of aluminum, etc., and electrolytic plating of copper, nickel, zinc, chromium, gold, etc. Further, in the recovery method according to the present invention, not only the platinum group metal can be recovered from the metal base material, but also the metal base material can be recovered. That is, it can be said that the materials constituting the laminate are separated and recovered.
  • the shape of the metal base material will be left so that it can be recycled. If the new shape does not remain (if it has already been cut, crushed, etc.), the material of the base material or the platinum group metal layer is recovered. That is, in the recovery method according to the present invention, no mechanical impact is applied to the laminated body.
  • the platinum group metal is recovered from the laminate according to the above policy. Therefore, the recovery method according to the present invention provides a chemical separation method and an electrolytic separation method.
  • the metal base material (for example, titanium) of the laminate when exposed to an aqueous solution containing fluorine, it violently releases hydrogen to generate fluoride (fluorotitanium ion (H2TiF6)).
  • fluoride fluorotitanium ion (H2TiF6)
  • H2TiF6 fluorotitanium ion
  • the chemical separation method is easy as it only requires immersing the laminate in a solution, but it also dissolves a metal substrate (for example, titanium) and recovers the solid metal substrate in its original shape. It is not possible.
  • a constant positive voltage is applied in an electrolytic solution that is a fluorine-containing aqueous solution, hydrofluoric acid is generated near the surface of the laminated body that has become an anode, the metal base material is dissolved, and as a result, the platinum group metal layer is formed. Peel off.
  • the anodized film is formed on the surface of the metal substrate after melting, further melting can be suppressed as much as possible after the platinum group metal layer is peeled off. As a result, the peeling of the platinum group metal layer can be automatically stopped, and the metal substrate can be recovered without destroying its shape.
  • the electrolytic solution that can be used here is a liquid containing fluorine. More specifically, an aqueous solution of a fluorine salt can be preferably used. For example, ammonium fluoride can be suitably used. Such a fluorine-containing liquid can be used at a pH of around 7, and is safer than the chemical separation method.
  • the concentration of the fluorine salt is preferably 1M to 4M.
  • the depot reaction is a reaction of forming an oxide film (insulator), and the liquid temperature rises significantly at a constant current density. Since the rise in liquid temperature greatly accelerates the etching reaction on the other side, the etching reaction is superior to the depot reaction, and as a result, the metal substrate becomes thin. Therefore, it is preferable to have a cooling means for stabilizing the temperature of the electrolytic solution.
  • the metal substrate is exposed (after the peeling stage of the platinum group metal layer has progressed), it is preferable to perform an operation of lowering the current density and suppressing the rise in liquid temperature.
  • the exposure of the metal substrate may be detected under constant current conditions, and then the current may be reduced, but the most preferable is to proceed with the peeling process under constant "voltage" conditions.
  • the laminated bodies are paired and immersed in an electrolytic solution, and an alternating current is applied.
  • the platinum group metal layers can be peeled off when they become anodes with each other, so that effective peeling recovery is possible.
  • the peeling device 1 includes a peeling tank 10, a negative electrode portion 12, a positive electrode portion 14, and a power supply 16. Further, a control device 18 for controlling the power supply 16 may be provided. Further, a thermometer 22 for measuring the temperature of the solvent in the peeling tank 10, a pH meter 24 for measuring the pH, and a constant temperature device 26 for keeping the temperature of the electrolytic solution in a constant temperature state may be arranged.
  • the power supply 16 is provided with a constant voltage source 16a, an ammeter 16e, and a voltmeter 16f.
  • the voltmeter 16f measures the voltage between the negative electrode portion 12 and the positive electrode portion 14.
  • the ammeter 16e measures the current flowing between the negative electrode portion 12 and the positive electrode portion 14.
  • the power supply 16 may be provided with a constant current source 16b, an AC power supply 16c, and a changeover switch 16d for switching between the constant voltage source 16a, the constant current source 16b, and the AC power supply 16c. Further, it is desirable that the polarities of the constant current source 16b and the constant voltage source 16a can be exchanged.
  • the control device 18 receives the signals Sa and Sv from the ammeter 16e and the voltmeter 16f.
  • the signal Sa is the current value flowing between the positive electrode portion 14 and the negative electrode portion 12 measured by the ammeter 16e
  • the signal Sv is the voltage value between the positive electrode portion 14 and the negative electrode portion 12 measured by the ammeter 16f. Represent each.
  • the control device 18 instructs the constant voltage source 16a of the output voltage value by the output instruction signal Ca.
  • the output instruction signal Ca is the output polarity and output voltage value for the constant voltage source 16a, the output polarity and output current value for the constant current source 16b, and the output voltage value and output signal for the AC power supply 16c.
  • the frequency can also be specified.
  • the side where the changeover switch 16d is provided is the negative electrode portion 12 side.
  • the control device 18 can transmit the changeover signal Cs to the changeover switch 16d. Any one of the constant voltage source 16a, the constant current source 16b, and the AC power supply 16c can be selected and output by the switching signal Cs.
  • the control device 18 monitors the current value while processing at a constant voltage. Then, when the decrease point at which the current value decreases is detected, the output from the power supply 16 is stopped. This means that the peeling process by the constant voltage is stopped.
  • the point of decrease is clearly the point where the current flowing between the anode and the cathode has turned in the decreasing direction. As will be described later, it is relatively easy to determine the point of decrease when the time change of the flowing current is viewed later. However, it is not easy to determine the point of decrease when monitoring the ever-changing current value. If you wait too long for the current value to decrease, the amount of dissolved metal substrate will increase, resulting in unnecessary power consumption.
  • the voltage finally applied causes 70% to 90% of the current flowing between the anode and the cathode, it may be a reduction point.
  • the "last applied voltage” means the voltage when the same voltage is applied from the initial application of the voltage to the stop. Further, when a relatively high voltage is applied at the beginning of applying a voltage and then changed to a lower voltage, it means 70% to 90% of the current flowed by the last applied voltage.
  • control device 18 can also receive signals St and Sph from the thermometer 22 and the pH meter 24 for measuring the temperature of the electrolytic solution 10 m in the peeling tank 10. Further, the control device 18 can send an instruction signal Ct to the constant temperature device 26.
  • the constant temperature device 26 is not particularly limited as long as it can control the temperature of the electrolytic solution 10 m to be constant.
  • the temperature of the electrolytic solution 10 m may be controlled by passing a liquid or gas that can be heated and cooled to a constant temperature through a tube 26a arranged in the stripping tank 10.
  • the control device 18 monitors the temperature of the electrolytic solution 10 m with a thermometer 22, and if the temperature becomes higher than the planned temperature, , The instruction signal Ct for lowering the temperature is sent to the constant temperature device 26, and when the temperature becomes lower, the instruction signal Ct for increasing the temperature is sent.
  • control device 18 is provided with an input unit for inputting instructions to the control device 18 itself and a display unit (not shown) capable of showing the current overall state of the peeling device 1. good.
  • the cathode plate 52 is attached to the negative electrode portion 12 in a state where conductivity is ensured. Further, the laminated body 50 in which the platinum group metal layer 50a is formed on the metal base material 50b is attached to the positive electrode portion 14 in a state where conductivity is ensured. Then, the constant voltage source 16a and the constant current source 16b are controlled by the control device 18, and the electrolytic separation method is carried out by applying electric power between the electrodes to peel off the platinum group metal layer 50a on the laminated body 50.
  • Example 1 10 g of ammonium fluoride (NH 4 F) and 400 cc of pure water were placed in a beaker to dissolve ammonium fluoride. This is a 0.675 M aqueous solution of ammonium fluoride.
  • the mesh-like material used as the anode for electrolytic plating was used as a pair.
  • One laminate was used as an anode and the other laminate was used as a cathode, and a voltage of 10 V was applied between the two laminates. At this time, a current of 1.75 A flowed.
  • Figure 2 shows the change in the current value after the current started to flow.
  • the current value was constant for about 20 minutes after the current started to flow, but then gradually decreased.
  • a black powder settled under the laminate as the anode while the current value was constant. After the current value began to decrease, an interference film was formed on the black laminate and it became rainbow-colored.
  • the current decreased because titanium oxide was formed on the surface of the anode after the current was applied and became a non-conductor. That is, if the current value is monitored, the peeling of the platinum group metal layer can be confirmed. Further, even if the titanium substrate is left as it is, if an anodized film is formed on the surface of the titanium substrate, the current automatically stops flowing and the processing can be automatically stopped.
  • iridium 22% by mass, which was almost the same as the iridium concentration confirmed in Example 1, and the platinum group metal layer was almost 100%. It turned out to be peeling off.
  • the anode was replaced with a new laminate and the same procedure was performed, but the change in the current value was confirmed for the second sheet as well as for the first sheet (see Fig. 2).
  • black powder was precipitated under the anode, and when elemental analysis was performed, almost all iridium was exfoliated as in the first sheet.
  • Example 2 The same sample and peeling device as in Example 1 were prepared, and the polarity of the power supply was changed every 30 seconds. The change in the current value decreased after a certain period of time, as in the case of Example 12 (see FIG. 2). A bubble generator was placed near the anode and cathode so that the ammonium fluoride aqueous solution near the electrodes was always fresh. When both poles were taken out after the current value became sufficiently low, peeling of the platinum group metal layer was confirmed in both poles.
  • FIG. 3 shows the results when a laminate (sample) in which iridium oxide was formed on a titanium metal substrate was electrolytically separated at a constant current.
  • electrolytic solution 4M ammonium fluoride (NH 4F) was used, and the current was constant at 5.34A for all the samples.
  • a laminated body was connected to the positive electrode portion, the cathode plate connected to the negative electrode portion was Ti, and the distance between the electrodes was 5 mm.
  • Samples 1, 2 and 3 have different sizes and iridium thicknesses.
  • the horizontal axis is the processing time (min)
  • the vertical axis is the voltage (V) between the electrodes of the negative electrode portion and the positive electrode portion.
  • the voltage value seemed to be almost constant, but in detail, the voltage value fluctuated.
  • iridium was exfoliated from the sample at the anode.
  • FIG. 4 is a graph showing changes in processing in the case of other samples.
  • the cathode plate was replaced with stainless steel.
  • the applied current was 7 A.
  • the horizontal axis is the processing time (min).
  • the vertical axis of FIG. 4A is the applied voltage between the electrodes, and the vertical axis of FIG. 4B is the measurement of the dissolved amount (mg / L) of Ti, which is a metal substrate.
  • the vertical axis of FIG. 4C is the temperature (° C.) of the electrolytic solution.
  • the dissolution of Ti started from the surface of the metal substrate 5 minutes after the start of the treatment (referred to as point B) before the point E where the voltage suddenly increased.
  • point B the increase in the amount of dissolution between the points B and E was proportional to the time. This is called “time-proportional increase”.
  • time-proportional increase In FIG. 4 (b), it is represented by the line L.
  • iridium is still exfoliating, so it is not easy to determine when to stop the process because as much iridium (platinum group light metal) as possible is exfoliated while leaving as much metal base material as possible.
  • iridium platinum group light metal
  • the voltage rises sharply a large amount of the metal base material is melted with a slight time delay, so that the metal base material becomes thin and the reuse of the metal base material is hindered.
  • FIG. 5 is a sample having the same form as that of FIG. 4, and has the same size, iridium thickness, and the like.
  • the electrolytic solution is 4M ammonium fluoride and the negative electrode is stainless steel.
  • the distance between the electrodes was 5 mm, which was the same as in FIG.
  • a constant voltage of 6.15 V was applied between the electrodes.
  • the horizontal axis is the processing time (min).
  • the vertical axis is the current (A)
  • the vertical axis in FIG. 7B is the dissolution amount of Ti (mg / L)
  • the vertical axis in FIG. 5C is the electrolytic solution.
  • the temperature ° C).
  • the "current flowing due to the last applied voltage” is 7A in the case of FIG. 4A, so the current value is set between 6.3A (90%) and 4.9A (70%).
  • the power supply may be stopped when the current value becomes smaller than the value.
  • the time when the current value reaches 6.3 A (90%) is indicated as “t 90 ”
  • the time when the current value reaches 4.9 A (70%) is indicated as “t 70 ”.
  • the power may be stopped at any time during this period. By doing so, it is possible to peel off and recover a metal base material having no unnecessary dissolution amount of Ti and having little damage and a sufficient amount of platinum group metal.
  • FIG. 6 shows the result of the processing in which the processing by the constant current and the processing by the constant voltage are combined.
  • the horizontal axis is time (min) and the vertical axis is current value (A).
  • a constant current (9A) is passed for a certain period from the start of the process (indicated as “Met1 (CA)” in FIG. 6), and the constant is determined after 10 minutes have passed.
  • the processing was performed by the voltage (9.7V) (indicated as “Met1 (CV)” in FIG. 6).
  • the constant voltage (9) from the start of the method 2 indicated as “Met2”
  • the process performed in (7V) (indicated as “Met2 (CV)” in FIG. 6) is shown in FIG.
  • Method 1 may be regarded as processing with a constant voltage. This is because in the electrolytic separation method, the resistance between the anode and the cathode is constant while the platinum group metal is attached. Further, as shown in FIG. 6, when the applied voltage is set to two stages, the "current flowing by the last applied voltage" is about 7A flowing by 9.7V.
  • the processing can be stopped in about 15 minutes in the method 1, but about 21 minutes must elapse in the method 2. If so, the processing cannot be stopped.
  • platinum can be treated in a short time while preventing the metal substrate from being rapidly melted.
  • the group metal can be peeled off.
  • Example 5 It can also be said that the result of FIG. 6 changed the voltage applied to the laminated body as the object to be processed.
  • the power supply was operated so that a high voltage was applied at the beginning of the processing and the voltage was lowered in the latter half of the processing.
  • FIG. 7 shows the result when the voltage is low at the initial stage of the processing and the applied voltage is gradually increased.
  • FIG. 7A shows the relationship between the processing time and the current value (A) between the electrodes
  • FIG. 7B shows the relationship between the voltage (V) applied between the electrodes and the processing time. ..
  • the horizontal axis is the (processing) time (min) and the vertical axis is the current (A).
  • the horizontal axis is the (processing) time (min)
  • the vertical axis is the set voltage (V) applied between the electrodes.
  • the applied voltage values were increased to 6V, 7.3V, 9V, 9.7V, and 11V every 5 minutes. After 3 minutes had passed after applying 11V, the current value started to decrease.
  • the metal substrate may start melting earlier than the platinum group metal on the surface of the laminate (processed object) is peeled off. It becomes difficult to recover the metal base material with less damage.
  • the platinum group metal When the film thickness of the platinum group metal of the object to be treated is unknown, the platinum group metal gradually peels off when the treatment is started from a low applied voltage and the applied voltage is increased over time as in this embodiment. , Platinum group metal can be reliably recovered, and a metal base material without thinning can be recovered.
  • Example 6 As the recovered raw material (laminated body), a mesh-like material used as an anode for electrolytic plating was used. (It is the same as that used in Example 1.) Hydrogen fluoride of 2% by mass, 10% by mass and 20% by mass was added to the recovered raw material and left for 30 minutes. In each case, hydrogen was released violently. When the recovered raw material was pulled up after 30 minutes had passed, what was initially black had a silvery luster. In addition, black powder was precipitated. From this, it was found that the platinum group metal formed on the titanium substrate can be completely exfoliated with hydrogen fluoride of 2% by mass or more.
  • FIG. 8 The result of elemental analysis of the black powdery precipitate is shown in FIG. With reference to FIG. 8, the horizontal axis shows the concentration of hydrofluoric acid (mass volume%), and the vertical axis shows the content rate (mass%). According to FIG. 1, aluminum, titanium, iridium, platinum, and others were detected. From this, it was found that the purity of iridium was about 25% by mass.
  • Example 7 To a test tube having a volume of 50 cm 3 , 2.6 mass by mass of hydrofluoric acid 20 cm 3 and a hydrogen peroxide solution having a predetermined concentration were added, and a titanium plate weighing 0.25 g was immersed therein. A stirrer was also placed in the test tube, and the inside of the test tube was stirred at a rotation speed of 500 rpm. The hydrogen concentration was measured at the position of the scale of 50 cm 3 in the test tube. The results are shown in FIG.
  • the horizontal axis is the reaction time (min) and the vertical axis is the detected hydrogen concentration (ppm).
  • the vertical axis is a logarithmic display.
  • the hydrogen peroxide solution was changed at concentrations of 0% by mass, 1.6% by mass, 3.2% by mass, and 6.3% by mass.
  • the hydrogen concentration which was 10,000 ppm when the hydrogen peroxide solution was not contained, was reduced to 100 ppm (to 1/100) by adding the hydrogen peroxide solution of 6.3% by mass by mass.
  • the recovery method according to the present invention can be suitably used as a method for recovering a platinum group metal and a metal base material from a laminate in which a platinum group metal layer is formed on a metal base material.

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Abstract

In a positive electrode for electrolytic plating, a titanium-iridium laminate is used. Therefore, it is desired to recovery a resource after disposal. However, these substances are extremely stable. Therefore, it is not easy to separate and recover these substances. Furthermore, it has been found that, when it is attempted to detach iridium using a constant current, the dissolution of titanium that is a metal base material occurs at once. Therefore, it is difficult to achieve both of the recovery of the metal base material in an undamaged form and the highly efficient recovery of a platinum-group metal.　The present invention is a method for recovering a platinum-group metal from a laminate comprising a metal base material and a layer of the platinum-group metal formed on the metal base material, the method including a step for immersing the laminate in a fluorine-containing aqueous solution and then applying a positive constant voltage to the laminate. This method can solve the above-mentioned problem.

Description

白金族金属の回収方法Platinum group metal recovery method
　本発明は、金属上に白金族金属、またはその酸化物の層が形成された積層体から白金族金属を回収する方法に関する。より具体的な一形態としては、白金族金属の層が形成された金属製電極基材から化学処理により、若しくは化学電解により白金族金属を回収する方法に関する。 The present invention relates to a method for recovering a platinum group metal from a laminate in which a platinum group metal or an oxide layer thereof is formed on the metal. As a more specific embodiment, the present invention relates to a method of recovering a platinum group metal from a metal electrode base material on which a platinum group metal layer is formed by chemical treatment or chemical electrolysis.
　塩水電解、電解水の製造、アルミニウム等の化成処理、銅、ニッケル、亜鉛、クロム、金等の電解めっきの陽極としてチタン、ジルコニウム、ニオブといった硬度の高い金属基材にイリジウムやルテニウムといった白金族金属、またはその酸化物の層を形成したものが用いられている。これらの物質は、硬度が高く、化学的に極めて安定な物質である。 Salt water electrolysis, electrolysis water production, chemical conversion treatment of aluminum, etc., platinum group metals such as iridium and ruthenium on hard metal substrates such as titanium, zirconium, and niobium as anodes for electrolytic plating of copper, nickel, zinc, chromium, gold, etc. , Or a layer of an oxide thereof is used. These substances have high hardness and are chemically extremely stable.
　ここで、金属基材の表面は白金族金属の層の付着力を高めるために粗面化されている。すると、白金族金属の層表面において、対極となる陰極との間に生じる電流密度が場所によって異なり、経年的に白金族金属の層に割れ（クラック）が生じ、劣化する。 Here, the surface of the metal base material is roughened in order to increase the adhesive force of the platinum group metal layer. Then, on the surface of the platinum group metal layer, the current density generated between the platinum group metal layer and the counter electrode is different depending on the location, and the platinum group metal layer is cracked and deteriorates over time.
　劣化した電極は、廃棄されるが、金属基材および白金族金属とも希少な資源であるため再利用が望まれる。しかし、これらの金属は極めて安定であり、容易なことでは分別回収はできない。 The deteriorated electrode is discarded, but it is desired to reuse it because both the metal base material and the platinum group metal are rare resources. However, these metals are extremely stable and cannot be separated and recovered easily.
　特許文献１には、電極を細かく切断した後、研磨によって白金族金属層を剥離し、その後酸洗浄することで白金族金属を除去する方法が開示されている。 Patent Document 1 discloses a method of removing a platinum group metal by finely cutting an electrode, peeling off the platinum group metal layer by polishing, and then acid cleaning.
　また、特許文献２には、フッ化物を主成分とする電解溶液に金または白金族金属被膜を有する金属基体からなる陽極、及び陰極を浸漬させ、これらの電極に電流を流すことにより陽極電解処理を行なって、金または白金族金属を回収する方法が開示されている。 Further, in Patent Document 2, an anode and a cathode made of a metal substrate having a gold or platinum group metal coating are immersed in an electrolytic solution containing fluoride as a main component, and an anode electrolytic treatment is performed by passing a current through these electrodes. Is disclosed as a method for recovering gold or a platinum group metal.
特開２００１－３０３１４１号公報：特許第４４５０９４５号Japanese Unexamined Patent Publication No. 2001-303141: Japanese Patent No. 4450945 特開平７－１０９５９４号公報：特許第２６３０７０２号Japanese Unexamined Patent Publication No. 7-109594: Japanese Patent No. 2630702
　チタン、ジルコニウム、ニオブといった硬度の高い金属基材上の、イリジウムやルテニウムといった白金族金属の層は、基材表面に、白金族金属イオンを含む溶液（例えば白金族のクロロ錯体溶液）を塗布し、焼成することで得られる。層の厚みを所定の値に調整するために、塗布・焼成を何度も繰り返して、製造される。一度金属基材上に形成された白金族金属層を剥離するのは容易ではない。 The layer of platinum group metal such as iridium and ruthenium on a hard metal substrate such as titanium, zirconium, and niob is coated with a solution containing platinum group metal ions (for example, a platinum group chlorocomplex solution) on the surface of the substrate. , Obtained by firing. It is manufactured by repeating coating and firing many times in order to adjust the thickness of the layer to a predetermined value. It is not easy to peel off the platinum group metal layer once formed on the metal substrate.
　例えば、ブラスト法等、積層体を空気中で機械的な力で剥離しようとすると、剥離した白金族金属、金属基材の粉塵が雰囲気に蔓延するため、粉塵爆発の危険性があった。また、特許文献１のように研磨で白金族金属の層を削り落とすのは、手間がかかりすぎる処理であり、大量の被処理物から効率よく白金族金属を回収できない。その上、異形表面（例えば、メッシュ状の電極構造）においては、ブラスト、研磨共に、均一な剥離が実現できず、回収効率が低いという問題もあった。 For example, when the laminated body was to be peeled off by mechanical force in the air such as by the blast method, the peeled platinum group metal and the dust of the metal base material spread in the atmosphere, and there was a danger of dust explosion. Further, scraping off the platinum group metal layer by polishing as in Patent Document 1 is a process that takes too much time and effort, and the platinum group metal cannot be efficiently recovered from a large amount of objects to be treated. In addition, on a deformed surface (for example, a mesh-shaped electrode structure), uniform peeling cannot be realized in both blasting and polishing, and there is also a problem that recovery efficiency is low.
　また、好ましくは、白金族の回収後の金属基材は、再利用が望まれているが、特許文献１のように処理金属を細かく切断したのでは、金属基材の再利用ができない。なお、ここでの再利用とは、金属基材上に再度白金族金属層を形成するリコートを含む意味である。 Further, preferably, the metal base material after recovery of the platinum group is desired to be reused, but the metal base material cannot be reused if the treated metal is finely cut as in Patent Document 1. The term "reuse" as used herein means to include a recoat that forms a platinum group metal layer again on the metal substrate.
　金属基材の再利用まで含めると特許文献２の陽極電解処理による白金族金属の回収は、効果的であるといえる。しかし、一定電流によって陽極電解処理を行うと、白金族金属が剥離され、金属基材の表面が出現してきた付近で急激に金属基材が溶解し、金属基材が急速に痩せ細るという課題があった。 It can be said that the recovery of platinum group metals by the anodic electrolysis treatment of Patent Document 2 is effective, including the reuse of the metal base material. However, when the anodic electrolysis treatment is performed with a constant current, the platinum group metal is peeled off, the metal base material is rapidly melted near the appearance of the surface of the metal base material, and the metal base material is rapidly thinned. there were.
　白金族金属が剥離し、金属基材が出現したタイミングは、定電流で陽極電解処理を行う場合、電圧が急激に上昇する時点をモニタすることで、判断することはできる。しかし、陽極となる被処理物の形状や、金属基材表面に形成された白金族金属の厚さのバラツキなどにより、白金族金属が剥離した際の電圧値の変化は非常に急峻な場合があり、処理を止めるタイミングがわかりにくいという課題があった。 The timing at which the platinum group metal is peeled off and the metal base material appears can be determined by monitoring the time when the voltage rises sharply when the anodic electrolysis treatment is performed with a constant current. However, due to the shape of the object to be treated as the anode and the variation in the thickness of the platinum group metal formed on the surface of the metal substrate, the change in the voltage value when the platinum group metal is peeled off may be very steep. There was a problem that it was difficult to understand when to stop processing.
　例えば、白金族金属を剥離する被処理物（陽極）への電解処理が不足すると、回収できなかった白金族金属の量が増え、効果的な処理と言えない。 For example, if the electrolytic treatment on the object to be treated (anode) that peels off the platinum group metal is insufficient, the amount of platinum group metal that could not be recovered increases, and it cannot be said to be an effective treatment.
　一方、白金族金属を剥離する被処理物（陽極）への電解処理が多すぎると、白金族金属は十分に回収できるが金属基材の痩せ細りが多くなり、金属基材の再利用ができなくなる。 On the other hand, if too much electrolytic treatment is applied to the object to be treated (anode) that peels off the platinum group metal, the platinum group metal can be sufficiently recovered, but the metal base material becomes thin and thin, and the metal base material can be reused. It disappears.
　なお、化学的に白金族金属を化学薬品だけで剥離しようとすると、以下の課題がある。積層体の形状はさまざまであるところ、パンチングメッシュ等の異形表面を有する金属基材上に白金族金属層が形成されていると、均一に白金族金属層を剥離させるのが困難であった。 If you try to chemically peel off platinum group metals using only chemicals, there are the following problems. Although the shapes of the laminated bodies are various, it is difficult to uniformly peel off the platinum group metal layer when the platinum group metal layer is formed on a metal base material having a deformed surface such as a punching mesh.
　片面のみ白金族金属層が形成された電極を対象にする場合、裏面は金属基材がむき出しの状態であり、ケミカルピールを適用する場合、裏面の基材溶解が著しい。結果、金属基材は再利用（リコート）できず、剥離処理後の金属基材の価値を損なうこととなる。 When targeting an electrode on which a platinum group metal layer is formed on only one side, the metal base material is exposed on the back side, and when chemical peel is applied, the base material on the back side is significantly dissolved. As a result, the metal base material cannot be reused (recoated), and the value of the metal base material after the peeling treatment is impaired.
　次に、例えば化学処理法等、薬液を接触させることにより、白金族金属層と金属基材の界面を溶解させて、白金族金属層を剥離させる場合、薬液の侵入は、白金族金属層の表面クラックが起点となることから、剥離時間は、表面クラック状態に依存する。そのため、表面クラックに応じた処理時間を設定する必要があり、一律の処理プロセスを設定することが困難であった。 Next, when the interface between the platinum group metal layer and the metal substrate is melted and the platinum group metal layer is peeled off by contacting the chemical solution, for example, by a chemical treatment method, the invasion of the chemical solution is caused by the platinum group metal layer. Since the surface crack is the starting point, the peeling time depends on the surface crack state. Therefore, it is necessary to set the treatment time according to the surface crack, and it is difficult to set a uniform treatment process.
　白金族金属層の剥離時間は、積層体の表面クラック状態に依存するため、剥離しやすい箇所と、しにくい箇所ができ、完全剥離が困難であった。 Since the peeling time of the platinum group metal layer depends on the surface crack state of the laminated body, there are some parts that are easy to peel off and some parts that are difficult to peel off, and it is difficult to completely peel off.
　一般に硫酸、塩酸、硝酸、フッ酸、シュウ酸といった酸性薬液に晒すため、作業安全性に課題があった。 Generally, it was exposed to acidic chemicals such as sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, and oxalic acid, so there was a problem with work safety.
　酸を用いた化学処理の場合、金属基材を溶解することにより水素ガスが大量に発生するため、作業安全性の観点で課題があった。 In the case of chemical treatment using acid, a large amount of hydrogen gas is generated by dissolving the metal base material, so there is a problem from the viewpoint of work safety.
　薬液中には剥離した微細な触媒粉が分散することとなり、固液分離に煩雑な手間を要し、さらに、固液分離効率（＝回収率）の点で課題があった。 The fine catalyst powder that had peeled off was dispersed in the chemical solution, which required complicated labor for solid-liquid separation, and further had a problem in terms of solution separation efficiency (= recovery rate).
　固液分離後の回収物には、薬液が付着しているため、後段で中和のためのアルカリ洗浄、さらに純水洗浄で薬液成分を除去する手間が必要であった。 Since the chemical solution adhered to the recovered product after the solid-liquid separation, it was necessary to take the trouble of removing the chemical solution component by alkaline cleaning for neutralization and further pure water cleaning in the subsequent stage.
　白金族金属層が剥離した部位から金属基材が露出し溶解・水素発生するため、薬液が気泡で白濁し、目視においても、剥離反応完了の終点が検知できなかった。 Since the metal base material was exposed from the part where the platinum group metal layer was peeled off and dissolved and hydrogen was generated, the chemical solution became cloudy with bubbles, and the end point of the peeling reaction completion could not be detected visually.
　白金族金属層が剥離した部位から金属基材が露出し溶解するため、薬液の有効成分が失活しやすく、高頻度で液を新品に入れ替えることが必要であり、コストが高いという課題があった。 Since the metal base material is exposed and melts from the part where the platinum group metal layer is peeled off, the active ingredient of the chemical solution is easily deactivated, it is necessary to replace the solution with a new one frequently, and there is a problem that the cost is high. rice field.
　本発明は上記の課題に鑑みて相当されたもので、積層体から白金族金属を回収するだけでなく、金属基材も効果的に回収する方法を提供するものである。 The present invention is equivalent in view of the above problems, and provides a method for effectively recovering not only a platinum group metal from a laminate but also a metal base material.
　具体的に本発明に係る白金族金属の回収方法は、
　金属基材上に白金族金属の層が形成された積層体から前記白金族金属を回収する方法であって、
　前記積層体と導電体を、フッ素を含む水溶液に浸漬する工程と、
　前記積層体を陽極、前記導電体を陰極として、前記陽極と前記陰極の間に定電圧を印加する工程を有することを特徴とする。 Specifically, the method for recovering a platinum group metal according to the present invention is as follows.
A method for recovering the platinum group metal from a laminate in which a platinum group metal layer is formed on a metal substrate.
The step of immersing the laminate and the conductor in an aqueous solution containing fluorine,
It is characterized by having a step of applying a constant voltage between the anode and the cathode, with the laminate as an anode and the conductor as a cathode.
　また、本発明に係る白金族金属の回収方法は、
　金属基材上に白金族金属の層が形成された積層体から前記白金族金属を回収する方法であって、
　前記積層体を、フッ素を含む水溶液に浸漬し、前記積層体に正の電圧印加する工程を有することを特徴とする。 Further, the method for recovering a platinum group metal according to the present invention is as follows.
A method for recovering the platinum group metal from a laminate in which a platinum group metal layer is formed on a metal substrate.
It is characterized by having a step of immersing the laminate in an aqueous solution containing fluorine and applying a positive voltage to the laminate.
　本発明に係る白金族金属の回収方法では、金属基材上に白金族金属の層が形成された積層体を、フッ素を含む水溶液に浸漬するだけで白金族金属層を剥離させるので、硬度の高い化学的に極めて安定な白金族金属層を容易に剥離させることができる。 In the method for recovering a platinum group metal according to the present invention, the platinum group metal layer is peeled off by simply immersing the laminate in which the platinum group metal layer is formed on the metal substrate in an aqueous solution containing fluorine, so that the hardness is high. The highly chemically stable platinum group metal layer can be easily peeled off.
　また、金属基材はフッ酸に接触すると、激しく水素を発生するが、過酸化水素を、フッ素を含む水溶液に混入させることで、水素の発生を大幅に抑制することができ、安全に白金族金属を回収することができる。 In addition, the metal substrate violently generates hydrogen when it comes into contact with fluorine, but by mixing hydrogen hydrogen into an aqueous solution containing fluorine, the generation of hydrogen can be significantly suppressed, and the platinum group can be safely used. Metal can be recovered.
　また、本発明に係る白金族金属の回収方法は、積層体を、フッ素を含む水溶液（以後「電解用溶液」と呼ぶ。）中に浸漬させ、陽電圧を印加する。このようにすると、基材溶解部位から、白金族金属層を剥離（リフトオフ）し、回収することができる。 Further, in the method for recovering a platinum group metal according to the present invention, the laminate is immersed in an aqueous solution containing fluorine (hereinafter referred to as "electrolytic solution"), and a positive voltage is applied. In this way, the platinum group metal layer can be peeled off (lifted off) from the substrate dissolution site and recovered.
　一方、白金族金属層が剥離し、基材が露出した部位は、その後さらに、積層体（被処理物）に陽電圧を印加し続けると、基材を守る反応（デポ）、基材を溶かす反応（エッチング）が同時に起こることにより、白金族剥離後の金属基材は、溶解を極力抑えることができ、リコート可能な状態で回収できることとなる。 On the other hand, in the portion where the platinum group metal layer is peeled off and the base material is exposed, when a positive voltage is continuously applied to the laminated body (object to be treated), the reaction (depot) that protects the base material and the base material are melted. Since the reaction (etching) occurs at the same time, the metal substrate after the platinum group is peeled off can suppress the dissolution as much as possible and can be recovered in a recoatable state.
　したがって、本発明の回収方法であれば、白金族金属の膜厚にバラツキがあっても、白金族金属だけを効果的に回収することができ、金属基材表面が白金族金属を積層する前の、もともとの状態（粗面化された状態）と同等の状態で金属基材を回収することができる。 Therefore, according to the recovery method of the present invention, even if the film thickness of the platinum group metal varies, only the platinum group metal can be effectively recovered, and the surface of the metal substrate is before the platinum group metal is laminated. The metal substrate can be recovered in the same state as the original state (roughened state).
　また、剥離処理の前半を高い電圧（定電圧であっても定電流であってもよい。）で処理し、後半を定電圧で処理することで、定電圧だけの処理の場合より短くすることができる。 In addition, the first half of the peeling process is processed with a high voltage (which may be constant voltage or constant current), and the second half is processed with a constant voltage, which is shorter than the case of processing only with a constant voltage. Can be done.
　さらに、積層体にかける陽電圧を徐々に大きくすることで、白金族金属の厚みが判らない場合であっても、基材を溶解しすぎることなく、白金族金属を効率的に剥離することができる。 Furthermore, by gradually increasing the positive voltage applied to the laminate, even if the thickness of the platinum group metal is unknown, the platinum group metal can be efficiently peeled off without melting the base material too much. can.
　また、積層体を対にして電解用溶液中に浸漬させ、これらに交番電流を印加することで、積層体は交互に陽極となり、白金族金属の回収をより効果的に行うことができる。 Further, by immersing the laminated body in a pair in an electrolytic solution and applying an alternating current to these, the laminated body alternately becomes an anode, and the platinum group metal can be recovered more effectively.
本発明の回収方法を実施する剥離装置の構成を示す図である。It is a figure which shows the structure of the peeling apparatus which carries out the recovery method of this invention. 被処理物（積層体）を対にして電極とし、フッ化アンモニウム中で両積層体間に電圧をかけた場合の電流値の時間変化を示すグラフである。It is a graph which shows the time change of the current value when a voltage is applied between both laminated bodies in ammonium fluoride by making a pair of objects to be processed (laminated body) as electrodes. 積層体を陽極にし、フッ化アンモニウム中で定電流を印加した場合の電流の変化を示すグラフである。It is a graph which shows the change of the current when a constant current is applied in ammonium fluoride with a laminated body as an anode. 他の積層体として、フッ化アンモニウム中で定電流を印加した場合の電圧の変化（ａ）、金属基材（Ｔｉ）の溶解量（ｂ）、フッ化アンモニウムの液温（ｃ）を示すグラフである。As another laminate, a graph showing the change in voltage (a), the amount of dissolved metal substrate (Ti) (b), and the liquid temperature of ammonium fluoride (c) when a constant current is applied in ammonium fluoride. Is. 図４と同じサンプルに定電圧を印加した場合の電流の変化（ａ）、金属基材（Ｔｉ）の溶解量（ｂ）、フッ化アンモニウムの液温（ｃ）を示すグラフである。It is a graph which shows the change (a) of the electric current when a constant voltage is applied to the same sample as FIG. 4, the amount of dissolution (b) of a metal base material (Ti), and the liquid temperature (c) of ammonium fluoride. 定電流による処理と定電圧による処理を組み合わせた場合の電流値の変化を表すグラフである。It is a graph which shows the change of the current value when the processing by a constant current and the processing by a constant voltage are combined. 積層体を陽極にし、印加する電圧を一定時間毎に増加させた場合の電流値の変化（ａ）と、設定電圧の変化（ｂ）を示すグラフである。It is a graph which shows the change (a) of the current value and the change (b) of a set voltage when the laminated body is used as an anode, and the applied voltage is increased at regular time intervals. フッ化水素の濃度が異なる化学剥離によって回収した黒色粉末状の沈殿物の元素分析した結果を示す図である。It is a figure which shows the result of the elemental analysis of the black powdery precipitate recovered by the chemical stripping with different concentrations of hydrogen fluoride. フッ酸と濃度の異なる過酸化水素の混合液中にチタンを入れた場合に発生する水素の濃度を、過酸化水素の濃度毎に示す図である。It is a figure which shows the concentration of hydrogen generated when titanium is put in the mixed solution of hydrogen peroxide which has a different concentration with hydrofluoric acid for each concentration of hydrogen peroxide.
　以下に本発明に係る白金族金属の回収方法について実施例を示し説明を行う。なお、以下の説明は、本発明の一実施形態を例示するものであり、本発明は以下の説明に限定されるものではない。以下の説明は本発明の趣旨を逸脱しない範囲で改変することができる。なお、以下の説明では、「上」は基準となる金属基材の表面から離れる方向をいい、「下」は金属基材の表面に近づく方向をいう。また、「直上」および「直下」は間に他の層を含まない構成を言う。また、回収物中の注目する元素の濃度をその元素の「品位」とも呼ぶ。また、陽電圧、陰電圧は、正電圧、負電圧と同意である。また、定電圧は陽極と陰極間に一定の電圧が印加される制御であり、定電流は陽極と陰極間に一定の電流が流れる制御である。 Examples of the method for recovering a platinum group metal according to the present invention will be described below. The following description exemplifies one embodiment of the present invention, and the present invention is not limited to the following description. The following description can be modified without departing from the spirit of the present invention. In the following description, "upper" means a direction away from the surface of the reference metal base material, and "lower" means a direction closer to the surface of the metal base material. In addition, "directly above" and "directly below" refer to a configuration that does not include other layers in between. The concentration of the element of interest in the recovered material is also referred to as the "grade" of that element. In addition, positive voltage and negative voltage are synonymous with positive voltage and negative voltage. Further, the constant voltage is a control in which a constant voltage is applied between the anode and the cathode, and the constant current is a control in which a constant current flows between the anode and the cathode.
　本発明に係る白金族金属の回収方法（以後単に「本発明に係る回収方法」と呼ぶ。）は、金属基材上に白金族金属の層が形成された積層体を回収原料とする。ここで金属基材としては、チタン（Ｔｉ）、ジルコニウム（Ｚｒ）、ニオブ（Ｎｂ）といった４族、５族の元素を含む硬度の高い金属（合金を含む）が用いられている。また、白金族金属としては、白金（Ｐｔ）、金（Ａｕ）、イリジウム（Ｉｒ）やルテニウム（Ｒｕ）といった金属が用いられている。したがって、本発明における積層体は、これらの金属基材上に白金族金属が層状若しくはアイランド形状に形成された積層体である。 The method for recovering a platinum group metal according to the present invention (hereinafter, simply referred to as "recovery method according to the present invention") uses a laminate in which a layer of a platinum group metal is formed on a metal substrate as a recovery raw material. Here, as the metal base material, a metal (including an alloy) having a high hardness containing elements of Group 4 and Group 5 such as titanium (Ti), zirconium (Zr), and niobium (Nb) is used. Further, as the platinum group metal, metals such as platinum (Pt), gold (Au), iridium (Ir) and ruthenium (Ru) are used. Therefore, the laminate in the present invention is a laminate in which platinum group metals are formed in layers or islands on these metal substrates.
　このような積層体は、塩水電解、電解水の製造、アルミニウム等の化成処理、銅、ニッケル、亜鉛、クロム、金等の電解めっきの陽極電極としてよく用いられる。また、本発明に係る回収方法では、白金族金属を金属基材から回収するだけでなく、金属基材も回収することができる。すなわち、積層体を構成する材料を分離回収すると言ってよい。 Such a laminate is often used as an anode electrode for salt water electrolysis, electrolysis water production, chemical conversion treatment of aluminum, etc., and electrolytic plating of copper, nickel, zinc, chromium, gold, etc. Further, in the recovery method according to the present invention, not only the platinum group metal can be recovered from the metal base material, but also the metal base material can be recovered. That is, it can be said that the materials constituting the laminate are separated and recovered.
　したがって、積層体の新品状態の形状が残っている場合は、金属基材の形状を残し、リサイクルできるようにする。新品状態の形状が残っていない場合（すでに切断、粉砕等されている場合）は、基材や白金族金属の層の材料を回収する。すなわち、本発明に係る回収方法では、積層体への機械的な衝撃は行わない。 Therefore, if the new shape of the laminate remains, the shape of the metal base material will be left so that it can be recycled. If the new shape does not remain (if it has already been cut, crushed, etc.), the material of the base material or the platinum group metal layer is recovered. That is, in the recovery method according to the present invention, no mechanical impact is applied to the laminated body.
　本発明に係る回収方法では、上記のような方針で積層体から白金族金属を回収する。そこで、本発明に係る回収方法では、化学分離法と、電解分離法を提供する。 In the recovery method according to the present invention, the platinum group metal is recovered from the laminate according to the above policy. Therefore, the recovery method according to the present invention provides a chemical separation method and an electrolytic separation method.
　＜化学分離法＞
　積層体を構成する金属基材および白金族金属は、硬度が高く、化学的に極めて安定であり、王水にも溶けないが、フッ素を含有する水溶液には溶解することが知られている。 <Chemical separation method>
It is known that the metal base material and the platinum group metal constituting the laminate have high hardness, are chemically extremely stable, and are insoluble in aqua regia, but are soluble in an aqueous solution containing fluorine.
　また、積層体の金属基材（例えばチタン）は、フッ素を含む水溶液に晒されると、激しく水素を放出し、フッ化物（フルオロチタン酸イオン（Ｈ２ＴｉＦ６））を生成する。これは大量の積層体を処理する際に、大きなリスクを背負う処理となる。そこで、本発明に係る回収方法では、フッ素を含む水溶液に過酸化水素を添加する。過酸化水素の添加により、発生する水素は大幅に抑制することができ、積層体の大量処理であっても、大きな危険を回避することができる。 Further, when the metal base material (for example, titanium) of the laminate is exposed to an aqueous solution containing fluorine, it violently releases hydrogen to generate fluoride (fluorotitanium ion (H2TiF6)). This is a process that carries a large risk when processing a large amount of laminated body. Therefore, in the recovery method according to the present invention, hydrogen peroxide is added to the aqueous solution containing fluorine. By adding hydrogen peroxide, the generated hydrogen can be significantly suppressed, and even in a large-scale treatment of the laminated body, a great danger can be avoided.
　＜電解分離法＞
　化学分離法は積層体を溶液に浸漬するだけでよいので、方法としては容易であるが、金属基材（例えばチタン）をも溶解し、固形体の金属基材を元の形状のまま回収することはできない。しかし、フッ素含有水溶液である電解用溶液中で一定の陽電圧を印加すると、陽極となった積層体の表面近傍でフッ酸が生成され、金属基材が溶解し、その結果白金族金属層が剥離する。一方、金属基材表面は溶解後に陽極酸化皮膜が形成されるので、白金族金属層が剥離後は、それ以上の溶解を極力抑えることができる。この結果、白金族金属層の剥離を自動的に停止することができ、金属基材の形状を破壊することなく回収することができる。 <Electrolytic separation method>
The chemical separation method is easy as it only requires immersing the laminate in a solution, but it also dissolves a metal substrate (for example, titanium) and recovers the solid metal substrate in its original shape. It is not possible. However, when a constant positive voltage is applied in an electrolytic solution that is a fluorine-containing aqueous solution, hydrofluoric acid is generated near the surface of the laminated body that has become an anode, the metal base material is dissolved, and as a result, the platinum group metal layer is formed. Peel off. On the other hand, since the anodized film is formed on the surface of the metal substrate after melting, further melting can be suppressed as much as possible after the platinum group metal layer is peeled off. As a result, the peeling of the platinum group metal layer can be automatically stopped, and the metal substrate can be recovered without destroying its shape.
　より詳細には、例えば、ｐＨ４．５以上のフッ素含有溶液に積層体を含浸した場合、表面の白金族層、また裏面等で露出した金属基材ともに、化学的に無反応と言える。その理湯は、このｐＨ域で存在できるフッ素の形態はＦ－（フッ化物イオン）であり、金属エッチングに作用する活性種ではないことによる。 More specifically, for example, when a laminate is impregnated with a fluorine-containing solution having a pH of 4.5 or higher, it can be said that neither the platinum group layer on the front surface nor the metal substrate exposed on the back surface or the like is chemically unresponsive. This is because the form of fluorine that can exist in this pH range is F- (fluoride ion), and it is not an active species that acts on metal etching.
　一方、この状態で積層体に、正電圧を印加すると、陽極では酸素ガス（Ｏ２）加え、プロトン（Ｈ＋）が生成する。その結果、陽極表面（白金族触媒層表面）のみでは、電解液中のＦ－とプロトンが結びつき、フッ化水素酸（ＨＦ）が生成することとなる。回収対象の積層体は劣化状態（白金族触媒層表面にクラック）であるため、劣化部位（クラック）からＨＦが侵入し、金属基材（例えばチタン）を溶解することとなる。結果、基材溶解部位から、白金族金属層を剥離（リフトオフ）し、回収することができる。 On the other hand, when a positive voltage is applied to the laminate in this state, oxygen gas (O2) is added at the anode and protons (H +) are generated. As a result, only on the surface of the anode (the surface of the platinum group catalyst layer), F− in the electrolytic solution and the proton are bound to generate hydrofluoric acid (HF). Since the laminate to be recovered is in a deteriorated state (cracks on the surface of the platinum group catalyst layer), HF invades from the deteriorated portion (cracks) and dissolves the metal base material (for example, titanium). As a result, the platinum group metal layer can be peeled off (lifted off) from the substrate dissolution site and recovered.
　一方、白金族金属層が剥離し、基材が露出した部位は、その後さらに、積層体（被処理物）に陽電圧を印加し続けると、以下の２つの反応が同時に起こる。
（１）陽極酸化に伴う、金属基材表面への酸化物層（酸化皮膜）の形成反応（＝デポ）
（２）ＨＦの生成に伴う、前記酸化被膜の溶解反応（＝エッチング）
上記の様に、基材を守る反応（「デポ反応」と呼ぶ）、基材を溶かす反応（「エッチング反応」と呼ぶ。）が同時に起こることにより、白金族剥離後の金属基材は、溶解を極力抑えることができ、リコート可能な状態で回収できることとなる。 On the other hand, in the portion where the platinum group metal layer is peeled off and the base material is exposed, the following two reactions occur at the same time when a positive voltage is continuously applied to the laminated body (object to be treated).
(1) Reaction of forming an oxide layer (oxide film) on the surface of a metal substrate due to anodization (= depot)
(2) Dissolution reaction (= etching) of the oxide film accompanying the formation of HF
As described above, the reaction to protect the base material (called "depot reaction") and the reaction to melt the base material (called "etching reaction") occur at the same time, so that the metal base material after platinum group exfoliation is dissolved. Can be suppressed as much as possible, and can be collected in a recoatable state.
　なお、ここで用いることができる電解用溶液はフッ素が含有された液体である。より具体的にはフッ素塩の水溶液が好適に利用できる。例えば、フッ化アンモニウムは好適に利用できる。このようなフッ素を含有する液体は、ｐＨが７付近で使用することができ、化学分離法よりも安全性が高い。フッ素塩の濃度は１Ｍ～４Ｍが好適に利用できる。 The electrolytic solution that can be used here is a liquid containing fluorine. More specifically, an aqueous solution of a fluorine salt can be preferably used. For example, ammonium fluoride can be suitably used. Such a fluorine-containing liquid can be used at a pH of around 7, and is safer than the chemical separation method. The concentration of the fluorine salt is preferably 1M to 4M.
　また、フッ化アンモニウムは中性ｐＨであるため、積層体を浸すだけでは、無反応（金属基材は溶解しない）であり、電解を印加した時のみ、金属基材の溶解反応が起きることとなる（デポ反応とエッチング反応）。金属基材のリコートを考慮する場合、金属基材の溶解反応の制御は非常に重要であり、電解のＯＮ／ＯＦＦのみで反応を制御できるという点でＮＨ４Ｆは好適である。 In addition, since ammonium fluoride has a neutral pH, there is no reaction (the metal substrate does not dissolve) just by immersing the laminate, and the dissolution reaction of the metal substrate occurs only when electrolysis is applied. (Depot reaction and etching reaction). When considering the recoating of the metal base material, it is very important to control the dissolution reaction of the metal base material, and NH4F is suitable in that the reaction can be controlled only by turning on / off the electrolysis.
　また、ここで印加する電気エネルギーとして定電流源を用いると、金属基材表面に陽極酸化膜ができると共に、金属基材表面からの溶解量が急激に増加し、金属基材の痩せ細りが生じた。 Further, when a constant current source is used as the electric energy applied here, an anodic oxide film is formed on the surface of the metal substrate, and the amount of dissolution from the surface of the metal substrate increases sharply, resulting in thinning of the metal substrate. rice field.
　これは、エッチング反応がデポ反応を大幅に上回っていることによるものであり、白金族層が剥離し金属基材露出した後も、露出前と同等の電流密度を印加することが原因と推測される。デポ反応は酸化物被膜（絶縁体）の形成反応であり、一定電流密度では液温が大きく上昇することとなる。液温の上昇はもう一方のエッチング反応を大きく加速するため、エッチング反応がデポ反応より卓越する結果、金属基材がやせ細る。従って、電解液の液温は、一定化のための冷却手段を有することが好ましい。 This is because the etching reaction far exceeds the depot reaction, and it is presumed that the current density equivalent to that before exposure is applied even after the platinum group layer is peeled off and the metal substrate is exposed. To. The depot reaction is a reaction of forming an oxide film (insulator), and the liquid temperature rises significantly at a constant current density. Since the rise in liquid temperature greatly accelerates the etching reaction on the other side, the etching reaction is superior to the depot reaction, and as a result, the metal substrate becomes thin. Therefore, it is preferable to have a cooling means for stabilizing the temperature of the electrolytic solution.
　さらに、金属基材が露出した後は（白金族金属層の剥離段階が進んだ後は）、電流密度を低下させ、液温上昇を抑える操作を行うことが好ましい。定電流条件にて、金属基材の露出を検出し、以降、電流を下げる操作を行っても良いが、最も好ましいのは、剥離処理一連を、一定「電圧」条件で進めることである。 Further, after the metal substrate is exposed (after the peeling stage of the platinum group metal layer has progressed), it is preferable to perform an operation of lowering the current density and suppressing the rise in liquid temperature. The exposure of the metal substrate may be detected under constant current conditions, and then the current may be reduced, but the most preferable is to proceed with the peeling process under constant "voltage" conditions.
　基材露出前までは、白金族層が存在するため、電流が流れやすい（抵抗が低い）。一方、基材露出後は、デポ反応が起こるため、電流が流れにくい（抵抗が高い）状態となる。これら一連を定電圧条件で処理すると、抵抗の増大に伴い、必然的に電流密度が低下することとなるため、定電流時の課題であった、液温上昇に伴い、金属基材のやせ細りを大幅に改善することができる。 Because the platinum group layer exists before the base material is exposed, current easily flows (low resistance). On the other hand, after the base material is exposed, a depot reaction occurs, so that it becomes difficult for current to flow (high resistance). When these series are processed under constant voltage conditions, the current density inevitably decreases as the resistance increases. It can be greatly improved.
　また、本発明に係る回収方法では、積層体を対にして電解用溶液中に浸漬させ、交番電流を印加する。このようにすると、互いに陽極となった時に白金族金属層を剥離することができるので、効果的な剥離回収が可能となる。 Further, in the recovery method according to the present invention, the laminated bodies are paired and immersed in an electrolytic solution, and an alternating current is applied. By doing so, the platinum group metal layers can be peeled off when they become anodes with each other, so that effective peeling recovery is possible.
　＜剥離装置＞
　本発明に係る回収方法を実行する剥離装置について図１を参照しながら説明する。剥離装置１は、剥離槽１０と、陰電極部１２と、陽電極部１４と電源１６で構成される。また、電源１６を制御する制御装置１８が設けられていてもよい。また、剥離槽１０内の溶媒の温度を測定する温度計２２、ｐＨを測定するｐＨ計２４、電解用溶液の温度を恒温状態にする恒温装置２６が配置されていてもよい。 <Peeling device>
A peeling device for executing the recovery method according to the present invention will be described with reference to FIG. The peeling device 1 includes a peeling tank 10, a negative electrode portion 12, a positive electrode portion 14, and a power supply 16. Further, a control device 18 for controlling the power supply 16 may be provided. Further, a thermometer 22 for measuring the temperature of the solvent in the peeling tank 10, a pH meter 24 for measuring the pH, and a constant temperature device 26 for keeping the temperature of the electrolytic solution in a constant temperature state may be arranged.
　電源１６は、定電圧源１６ａと電流計１６ｅと電圧計１６ｆが設けられている。ここで電圧計１６ｆは陰電極部１２と陽電極部１４の間の電圧を測定する。電流計１６ｅは、陰電極部１２と陽電極部１４の間に流れる電流を測定する。 The power supply 16 is provided with a constant voltage source 16a, an ammeter 16e, and a voltmeter 16f. Here, the voltmeter 16f measures the voltage between the negative electrode portion 12 and the positive electrode portion 14. The ammeter 16e measures the current flowing between the negative electrode portion 12 and the positive electrode portion 14.
　また、電源１６は、定電流源１６ｂと交流電源１６ｃと、定電圧源１６ａ、定電流源１６ｂ、交流電源１６ｃを切り替える切換スイッチ１６ｄが設けられていてもよい。また、定電流源１６ｂと定電圧源１６ａは極性が入れ替えられるようにできれば望ましい。 Further, the power supply 16 may be provided with a constant current source 16b, an AC power supply 16c, and a changeover switch 16d for switching between the constant voltage source 16a, the constant current source 16b, and the AC power supply 16c. Further, it is desirable that the polarities of the constant current source 16b and the constant voltage source 16a can be exchanged.
　制御装置１８は、電流計１６ｅと電圧計１６ｆからの信号ＳａおよびＳｖを受信する。信号Ｓａは電流計１６ｅが測定した陽電極部１４と陰電極部１２の間に流れる電流値を、信号Ｓｖは電圧計１６ｆが測定した陽電極部１４と陰電極部１２の間の電圧値をそれぞれ表す。 The control device 18 receives the signals Sa and Sv from the ammeter 16e and the voltmeter 16f. The signal Sa is the current value flowing between the positive electrode portion 14 and the negative electrode portion 12 measured by the ammeter 16e, and the signal Sv is the voltage value between the positive electrode portion 14 and the negative electrode portion 12 measured by the ammeter 16f. Represent each.
　また、制御装置１８は、定電圧源１６ａに出力指示信号Ｃａで出力電圧値を指示する。出力指示信号Ｃａは定電圧源１６ａに対しては出力極性と出力電圧値、定電流源１６ｂに対しては出力極性と出力電流値、交流電源１６ｃに対しては、出力電圧値および出力信号の周波数も指示できるようにすることができる。なお、通常は、切換スイッチ１６ｄが設けられている側を陰電極部１２側とする。このように電源が複数ある場合、制御装置１８は、切換スイッチ１６ｄに対して切換信号Ｃｓを送信することができる。切換信号Ｃｓによって、定電圧源１６ａ、定電流源１６ｂ、交流電源１６ｃの何れかを選択し、出力することができる。 Further, the control device 18 instructs the constant voltage source 16a of the output voltage value by the output instruction signal Ca. The output instruction signal Ca is the output polarity and output voltage value for the constant voltage source 16a, the output polarity and output current value for the constant current source 16b, and the output voltage value and output signal for the AC power supply 16c. The frequency can also be specified. Normally, the side where the changeover switch 16d is provided is the negative electrode portion 12 side. When there are a plurality of power supplies in this way, the control device 18 can transmit the changeover signal Cs to the changeover switch 16d. Any one of the constant voltage source 16a, the constant current source 16b, and the AC power supply 16c can be selected and output by the switching signal Cs.
　制御装置１８は、定電圧で処理している際に、電流値をモニタする。そして、電流値が減少する減少点を検出したら電源１６からの出力を停止する。これは定電圧による剥離処理を停止することを意味する。減少点は、明らかに陽極と陰極間に流れる電流が減少方向に転じた点である。後述するように流れる電流の時間変化を後から見れば減少点を決めるのは比較的容易である。しかし、時々刻々と変化する電流値をモニタしている際に減少点をきめるのは容易ではない。電流値が減少するのを待ちすぎると金属基材の溶解量が増え、不要な電力の消費になる。 The control device 18 monitors the current value while processing at a constant voltage. Then, when the decrease point at which the current value decreases is detected, the output from the power supply 16 is stopped. This means that the peeling process by the constant voltage is stopped. The point of decrease is clearly the point where the current flowing between the anode and the cathode has turned in the decreasing direction. As will be described later, it is relatively easy to determine the point of decrease when the time change of the flowing current is viewed later. However, it is not easy to determine the point of decrease when monitoring the ever-changing current value. If you wait too long for the current value to decrease, the amount of dissolved metal substrate will increase, resulting in unnecessary power consumption.
　発明者の実験によれば、最後に印加した電圧によって陽極と陰極間に流れた電流の７０％～９０％になれば、減少点としてよい。「最後に印加した電圧」というのは、電圧の印加初期から停止まで同じ電圧にした場合は、その電圧をいう。また、電圧を印加した当初は、比較的高い電圧を印加し、その後それより低い電圧に変えた場合は、最後に印加した電圧によって流れた電流の７０％～９０％を意味する。 According to the inventor's experiment, if the voltage finally applied causes 70% to 90% of the current flowing between the anode and the cathode, it may be a reduction point. The "last applied voltage" means the voltage when the same voltage is applied from the initial application of the voltage to the stop. Further, when a relatively high voltage is applied at the beginning of applying a voltage and then changed to a lower voltage, it means 70% to 90% of the current flowed by the last applied voltage.
　また、制御装置１８は、剥離槽１０中の電解用溶液１０ｍの温度を測定する温度計２２およびｐＨ計２４からの信号ＳｔおよびＳｐｈを受信することもできる。さらに、制御装置１８は、恒温装置２６に対する指示信号Ｃｔを送ることができる。 Further, the control device 18 can also receive signals St and Sph from the thermometer 22 and the pH meter 24 for measuring the temperature of the electrolytic solution 10 m in the peeling tank 10. Further, the control device 18 can send an instruction signal Ct to the constant temperature device 26.
　恒温装置２６は、電解用溶液１０ｍの温度を一定に制御できるものであれば、特に方式は問わない。例えば、一定温度に加熱冷却できる液体若しくは気体を剥離槽１０中に配置した管２６ａを通過させることで、電解用溶液１０ｍの温度を制御できるようにしてもよい。 The constant temperature device 26 is not particularly limited as long as it can control the temperature of the electrolytic solution 10 m to be constant. For example, the temperature of the electrolytic solution 10 m may be controlled by passing a liquid or gas that can be heated and cooled to a constant temperature through a tube 26a arranged in the stripping tank 10.
　剥離槽１０中の電解用溶液１０ｍの温度を一定に保持する制御を行う場合は、制御装置１８が、温度計２２で電解用溶液１０ｍの温度をモニタし、予定される温度より高くなる場合は、恒温装置２６に温度を下げる指示信号Ｃｔを送り、低くなる場合は、温度を高くする指示信号Ｃｔを送る。 When controlling to keep the temperature of the electrolytic solution 10 m in the stripping tank 10 constant, the control device 18 monitors the temperature of the electrolytic solution 10 m with a thermometer 22, and if the temperature becomes higher than the planned temperature, , The instruction signal Ct for lowering the temperature is sent to the constant temperature device 26, and when the temperature becomes lower, the instruction signal Ct for increasing the temperature is sent.
　なお、もちろん制御装置１８には、制御装置１８自身に使用者が指示を入力する入力部と、現在の剥離装置１の全体の状態を示すことができる表示部（図示せず）が備えられてよい。 Of course, the control device 18 is provided with an input unit for inputting instructions to the control device 18 itself and a display unit (not shown) capable of showing the current overall state of the peeling device 1. good.
　剥離装置１で電解分離法を行う場合は、まず陰電極部１２に陰極板５２を導電性が確保される状態で取り付ける。また、陽電極部１４には金属基材５０ｂ上に白金族金属層５０ａが形成されている積層体５０を導電性が確保される状態で取り付ける。そして、制御装置１８によって、定電圧源１６ａや定電流源１６ｂを制御し、電力を電極間にかけることで電解分離法を実施し、積層体５０上の白金族金属層５０ａを剥離させる。 When performing the electrolytic separation method with the peeling device 1, first, the cathode plate 52 is attached to the negative electrode portion 12 in a state where conductivity is ensured. Further, the laminated body 50 in which the platinum group metal layer 50a is formed on the metal base material 50b is attached to the positive electrode portion 14 in a state where conductivity is ensured. Then, the constant voltage source 16a and the constant current source 16b are controlled by the control device 18, and the electrolytic separation method is carried out by applying electric power between the electrodes to peel off the platinum group metal layer 50a on the laminated body 50.
　以下実施例で本発明に係る回収方法を説明する。 The recovery method according to the present invention will be described below with examples.
　（実施例１）
　ビーカーに１０ｇのフッ化アンモニウム（ＮＨ４Ｆ）と純水４００ｃｃを入れフッ化アンモニウムを溶解させた。これは０．６７５Ｍのフッ化アンモニウム水溶液である。回収源である積層体として電解めっきの陽極として使用されたメッシュ状のものを対として用いた。一方の積層体を陽極、他方の積層体を陰極にし、両積層体間に１０Ｖの電圧をかけた。この時１．７５Ａの電流が流れた。 (Example 1)
10 g of ammonium fluoride (NH 4 F) and 400 cc of pure water were placed in a beaker to dissolve ammonium fluoride. This is a 0.675 M aqueous solution of ammonium fluoride. As the laminate that was the recovery source, the mesh-like material used as the anode for electrolytic plating was used as a pair. One laminate was used as an anode and the other laminate was used as a cathode, and a voltage of 10 V was applied between the two laminates. At this time, a current of 1.75 A flowed.
　電流を流し始めてからの電流値の変化を図２に示す。電流を流し始めてから約２０分間は、電流値は一定であったが、その後徐々に電流値は下がった。電流値が一定の間、陽極とした積層体の下には、黒い粉末が沈殿した。電流値が下がり始めてからは、黒色の積層体に干渉膜が生じ虹色にみえるようになった。 Figure 2 shows the change in the current value after the current started to flow. The current value was constant for about 20 minutes after the current started to flow, but then gradually decreased. A black powder settled under the laminate as the anode while the current value was constant. After the current value began to decrease, an interference film was formed on the black laminate and it became rainbow-colored.
　このことより、電流通電後の陽極には酸化チタンが表面に形成され、不導体となったために、電流が低下したと考えられた。すなわち、電流値を監視しておけば、白金族金属層の剥離を確認することができる。また、このまま放置しておいても、チタン基材表面に陽極酸化膜が形成されれば、自動的に電流は流れなくなり、処理の自動停止が可能である。 From this, it was considered that the current decreased because titanium oxide was formed on the surface of the anode after the current was applied and became a non-conductor. That is, if the current value is monitored, the peeling of the platinum group metal layer can be confirmed. Further, even if the titanium substrate is left as it is, if an anodized film is formed on the surface of the titanium substrate, the current automatically stops flowing and the processing can be automatically stopped.
　また、陽極の下に沈殿していた黒色の粉末を元素分析してみると、イリジウムが２２質量％であり、実施例１で確認したイリジウム濃度とほぼ一致し、白金族金属層はほぼ１００％剥離しているのが判った。 Further, when the black powder precipitated under the anode was elementally analyzed, iridium was 22% by mass, which was almost the same as the iridium concentration confirmed in Example 1, and the platinum group metal layer was almost 100%. It turned out to be peeling off.
　また、陽極を新しい積層体に代えて同様に行ってみたが、２枚目についても１枚目同様の電流値の変化を確認できた（図２参照）。また、陽極の下に黒い粉末が沈殿しており、元素分析を行うと、１枚目同様にほぼすべてのイリジウムが剥離していた。 In addition, the anode was replaced with a new laminate and the same procedure was performed, but the change in the current value was confirmed for the second sheet as well as for the first sheet (see Fig. 2). In addition, black powder was precipitated under the anode, and when elemental analysis was performed, almost all iridium was exfoliated as in the first sheet.
　（実施例２）
　実施例１と同じサンプルおよび剥離装置を用意し、電源の極性を３０秒毎に陽極・陰極を入れ替えた。電流値の変化は実施例１２の場合と同様に、一定時間が経過した後に減少した（図２参照）。なお、陽極・陰極の近傍にバブル発生機を配置し、電極近傍のフッ化アンモニウム水溶液が常に新鮮なものとなるようにした。電流値が十分低くなった後に両極を取り出すと、両極とも白金族金属層の剥離が確認された。 (Example 2)
The same sample and peeling device as in Example 1 were prepared, and the polarity of the power supply was changed every 30 seconds. The change in the current value decreased after a certain period of time, as in the case of Example 12 (see FIG. 2). A bubble generator was placed near the anode and cathode so that the ammonium fluoride aqueous solution near the electrodes was always fresh. When both poles were taken out after the current value became sufficiently low, peeling of the platinum group metal layer was confirmed in both poles.
　（実施例３）
　図３にチタンの金属基材上に酸化イリジウムが形成された積層体（サンプル）を定電流で電解分離した場合の結果を示す。電解用溶液は４Ｍのフッ化アンモニウム（ＮＨ４Ｆ）を用い、電流はどのサンプルも５．３４Ａ一定で行った。陽電極部には積層体を接続し、陰電極部に接続する陰極板はＴｉとし、電極間距離は５ｍｍとした。 (Example 3)
FIG. 3 shows the results when a laminate (sample) in which iridium oxide was formed on a titanium metal substrate was electrolytically separated at a constant current. As the electrolytic solution, 4M ammonium fluoride (NH 4F) was used, and the current was constant at 5.34A for all the samples. A laminated body was connected to the positive electrode portion, the cathode plate connected to the negative electrode portion was Ti, and the distance between the electrodes was 5 mm.
　サンプル１、２、３はそれぞれ大きさおよびイリジウムの厚みが異なるものである。図３を参照して、横軸は処理時間（ｍｉｎ）であり、縦軸は陰電極部と陽電極部の電極間の電圧（Ｖ）である。処理が開始されると、電圧値はほぼ一定のように見えるものの、細かくみれば、電圧値は上下していた。この間、陽極部のサンプルからはイリジウムが剥離していた。 Samples 1, 2 and 3 have different sizes and iridium thicknesses. With reference to FIG. 3, the horizontal axis is the processing time (min), and the vertical axis is the voltage (V) between the electrodes of the negative electrode portion and the positive electrode portion. When the process was started, the voltage value seemed to be almost constant, but in detail, the voltage value fluctuated. During this time, iridium was exfoliated from the sample at the anode.
　それぞれのサンプル表面からイリジウムが剥離すると、金属基材上に酸化膜が形成され、導電率が低下する。電源は定電流であるので、電極間の電圧が急激に上昇した。電圧が急激に変化する時間が異なるのは、これらのサンプルのイリジウムの厚さや形状が異なるからである。このグラフが示す様に電圧値が急激に変化した時点で、処理を停止すればよいようにも見える。 When iridium is exfoliated from the surface of each sample, an oxide film is formed on the metal substrate and the conductivity decreases. Since the power supply has a constant current, the voltage between the electrodes rises sharply. The different times of voltage change are due to the different thickness and shape of the iridium in these samples. As shown in this graph, it seems that the processing should be stopped when the voltage value changes suddenly.
　図４は、他のサンプルの場合の処理の変化を示すグラフである。陰極板はステンレスに交換した。また、印加電流は７Ａとした。いずれのグラフも横軸は処理時間（ｍｉｎ）である。図４（ａ）の縦軸は電極間の印加電圧であり、図４（ｂ）の縦軸は金属基材であるＴｉの溶解量（ｍｇ／Ｌ）を測定したものである。図４（ｃ）の縦軸は電解用溶液の温度（℃）である。 FIG. 4 is a graph showing changes in processing in the case of other samples. The cathode plate was replaced with stainless steel. The applied current was 7 A. In each graph, the horizontal axis is the processing time (min). The vertical axis of FIG. 4A is the applied voltage between the electrodes, and the vertical axis of FIG. 4B is the measurement of the dissolved amount (mg / L) of Ti, which is a metal substrate. The vertical axis of FIG. 4C is the temperature (° C.) of the electrolytic solution.
　図３の場合同様に、金属基材上のイリジウムが剥離すると、金属基材表面が酸化され電極間電圧は上昇した。この点を図４（ａ）のＥ点で示した。また、Ｅ点と同じ時間を図４（ｂ）および図４（ｃ）にもＥ点として示した。 Similarly in the case of FIG. 3, when the iridium on the metal substrate was peeled off, the surface of the metal substrate was oxidized and the voltage between the electrodes increased. This point is shown by point E in FIG. 4 (a). Further, the same time as the point E is also shown as the point E in FIGS. 4 (b) and 4 (c).
　ここで、図４（ｂ）を参照すると、電圧が急激に上昇したＥ点より前の処理開始５分後（Ｂ点とする。）から金属基材表面からＴｉの溶解が始まっていた。この時Ｂ点からＥ点までの間の溶解量の増加は時間に比例した増加であった。これを「時間比例的な増加」と呼ぶ。図４（ｂ）では、ラインＬで表した。 Here, referring to FIG. 4B, the dissolution of Ti started from the surface of the metal substrate 5 minutes after the start of the treatment (referred to as point B) before the point E where the voltage suddenly increased. At this time, the increase in the amount of dissolution between the points B and E was proportional to the time. This is called "time-proportional increase". In FIG. 4 (b), it is represented by the line L.
　一方、電圧が急激に変化したＥ点以後は、時間比例的な増加以上のレートで金属基材が溶解した。すなわち、電圧が急激に変化した後は急激にＴｉの溶解量が増えた（白矢印参照）。 On the other hand, after the point E where the voltage changed sharply, the metal substrate melted at a rate higher than the time-proportional increase. That is, after the voltage changed sharply, the amount of Ti dissolved increased sharply (see the white arrow).
　この間まだイリジウムは剥離し続けているので、できるだけ多くのイリジウム（白金族軽金属）を、金属基材をできるだけ残しながら剥離させるため、いつ処理を停止すればよいかを判断するのは容易ではない。特に電圧が急激に高くなると、わずかな時間の遅れで大量の金属基材が溶解することによって、痩せ細り、金属基材の再利用の妨げとなる。 During this period, iridium is still exfoliating, so it is not easy to determine when to stop the process because as much iridium (platinum group light metal) as possible is exfoliated while leaving as much metal base material as possible. In particular, when the voltage rises sharply, a large amount of the metal base material is melted with a slight time delay, so that the metal base material becomes thin and the reuse of the metal base material is hindered.
　なお、図３と図４（ａ）では電圧の上昇の仕方が異なるが、電圧の上昇の仕方は積層体にかかる電流密度や積層体の形状で異なる。図４（ａ）では比較的ゆっくりと電圧が上昇しているように見えるが、図３のような電圧の上昇の仕方であると、電圧が上昇したと認識した時にはすでに、時間比例的な増加以上のレートで金属基材が溶解する状態になっている。したがって、処理をいつ停止するかを判断するのは一層困難となる。 Note that the method of increasing the voltage differs between FIGS. 3 and 4 (a), but the method of increasing the voltage differs depending on the current density applied to the laminate and the shape of the laminate. In FIG. 4A, it seems that the voltage rises relatively slowly, but with the method of voltage rise as shown in FIG. 3, when it is recognized that the voltage has risen, the voltage increases in proportion to time. The metal substrate is in a state of being melted at the above rate. Therefore, it becomes more difficult to determine when to stop processing.
　図５は、図４と同じ形態のサンプルで、大きさ、イリジウムの厚み等が同じサンプルである。電解用溶液は４Ｍのフッ化アンモニウムであり、陰電極はステンレスである。電極間間隔は５ｍｍであり、図４の場合と同じとした。ここではこの電極間に６．１５Ｖの一定電圧を印加した。 FIG. 5 is a sample having the same form as that of FIG. 4, and has the same size, iridium thickness, and the like. The electrolytic solution is 4M ammonium fluoride and the negative electrode is stainless steel. The distance between the electrodes was 5 mm, which was the same as in FIG. Here, a constant voltage of 6.15 V was applied between the electrodes.
　図５の各図は横軸が処理時間（ｍｉｎ）である。図５（ａ）は縦軸が電流（Ａ）であり、図７（ｂ）の縦軸はＴｉの溶解量（ｍｇ／Ｌ）であり、図５（ｃ）の縦軸は電解用溶液の温度（℃）である。図５（ａ）を参照して、電流が一定の領域の後、電流が急激に下がる点が生じた。これをＡ点とする。同じ時間を図５（ｂ）および図５（ｃ）にもＡ点として示した。 In each figure of FIG. 5, the horizontal axis is the processing time (min). In FIG. 5A, the vertical axis is the current (A), the vertical axis in FIG. 7B is the dissolution amount of Ti (mg / L), and the vertical axis in FIG. 5C is the electrolytic solution. The temperature (° C). With reference to FIG. 5A, there was a point where the current dropped sharply after a region where the current was constant. This is referred to as point A. The same time is also shown in FIGS. 5 (b) and 5 (c) as point A.
　図５（ａ）を再度参照して、Ａ点以後電流は下がり続けた。一方図５（ｂ）を参照すると、電流が急激に低下するＡ点の前（約５分）から金属基材のＴｉが溶解し始めている。図４と同様にＢ点とする。 With reference to FIG. 5 (a) again, the current continued to decrease after the point A. On the other hand, referring to FIG. 5 (b), Ti of the metal substrate begins to dissolve before point A (about 5 minutes) when the current drops sharply. Point B is used as in FIG.
　しかし、図４の定電流の場合と異なり、Ｔｉの溶解量が急激に多くはならず、時間比例的な増加程度のレートで多くなり、さらにその後時間比例的な増加のレートよりも低くなった（図５（ｂ）のＤ点）。図５（ｃ）の電解用溶液の温度も時間比例的な増加から明らかにレートが下がっており、流れる電流自体が急激に低下し、ジュール熱の発生がなくなっていることが示唆された。 However, unlike the case of the constant current in FIG. 4, the amount of Ti dissolved did not increase sharply, but increased at a rate of about a time-proportional increase, and then became lower than the rate of a time-proportional increase. (Point D in FIG. 5 (b)). The temperature of the electrolytic solution in FIG. 5 (c) also clearly decreased due to the time-proportional increase, suggesting that the flowing current itself decreased sharply and the generation of Joule heat was eliminated.
　これは、定電圧での処理は、Ｔｉの溶解力が急激に変化せず、電流変化をモニタしながら電源ＯＦＦの制御をしても、金属基材が予定以上に痩せ細ることを回避することができることを意味している。つまり停止の判断を容易に行うことができる。 This is because the processing at a constant voltage does not cause the dissolving power of Ti to change suddenly, and even if the power is turned off while monitoring the change in current, the metal substrate is prevented from becoming thinner than expected. Means that you can. That is, it is possible to easily determine the stop.
　例えば、「最後に印加した電圧によって流れる電流」は図４（ａ）の場合は、７Ａであるので、電流値が６．３Ａ（９０％）乃至４．９Ａ（７０％）の間に設定した値よりも電流値が小さくなった時点で電源を停止するとしてよい。図４（ａ）では、電流値が６．３Ａ（９０％）になった時点を「ｔ９０」と示し、電流値が４．９Ａ（７０％）になった時点を「ｔ７０」と示した。電源の停止はこの間のいつでもよい。このようにすることで、不要なＴｉの溶解量がなくダメージの少ない金属基材と、十分な量の白金族金属を剥離回収することができる。 For example, the "current flowing due to the last applied voltage" is 7A in the case of FIG. 4A, so the current value is set between 6.3A (90%) and 4.9A (70%). The power supply may be stopped when the current value becomes smaller than the value. In FIG. 4A, the time when the current value reaches 6.3 A (90%) is indicated as “t 90 ”, and the time when the current value reaches 4.9 A (70%) is indicated as “t 70 ”. rice field. The power may be stopped at any time during this period. By doing so, it is possible to peel off and recover a metal base material having no unnecessary dissolution amount of Ti and having little damage and a sufficient amount of platinum group metal.
　（実施例４）
　図６には、定電流による処理と、定電圧による処理を合わせた処理の結果を示す。図６を参照して、横軸は時間（ｍｉｎ）であり縦軸は電流値（Ａ）である。方法１（「Ｍｅｔ１」と示した。）では、処理の開始から一定の間は定電流（９Ａ）を流し（図６では「Ｍｅｔ１（ＣＡ）と示した。」）、１０分経過後から定電圧（９．７Ｖ）による処理を行った（図６では「Ｍｅｔ１（ＣＶ）と示した。）。一方、比較例として方法２（「Ｍｅｔ２」と示した。）処理開始時から定電圧（９．７Ｖ）で行った処理（図６では「Ｍｅｔ２（ＣＶ）」と示した。）を、図６中に示した。 (Example 4)
FIG. 6 shows the result of the processing in which the processing by the constant current and the processing by the constant voltage are combined. With reference to FIG. 6, the horizontal axis is time (min) and the vertical axis is current value (A). In method 1 (indicated as "Met1"), a constant current (9A) is passed for a certain period from the start of the process (indicated as "Met1 (CA)" in FIG. 6), and the constant is determined after 10 minutes have passed. The processing was performed by the voltage (9.7V) (indicated as “Met1 (CV)” in FIG. 6). On the other hand, as a comparative example, the constant voltage (9) from the start of the method 2 (indicated as “Met2”) processing. The process performed in (7V) (indicated as "Met2 (CV)" in FIG. 6) is shown in FIG.
　なお、方法１において定電流を流した区間は、一定電圧による処理とみてもよい。電解分離法では、白金族金属が付着している間は、陽極と陰極間の抵抗は一定であるからである。また、図６のように、印加電圧を２段階にした場合は、「最後に印加した電圧によって流れる電流」は、９．７Ｖによって流れた約７Ａである。 Note that the section in which a constant current is passed in Method 1 may be regarded as processing with a constant voltage. This is because in the electrolytic separation method, the resistance between the anode and the cathode is constant while the platinum group metal is attached. Further, as shown in FIG. 6, when the applied voltage is set to two stages, the "current flowing by the last applied voltage" is about 7A flowing by 9.7V.
　減少点を９．７Ｖによる電流（約７Ａ）から約８６％になった６Ａとすると、方法１では、約１５分で処理を停止することができるが、方法２では、約２１分経過しなければ処理を停止することができない。 Assuming that the decrease point is 6A, which is about 86% from the current (about 7A) at 9.7V, the processing can be stopped in about 15 minutes in the method 1, but about 21 minutes must elapse in the method 2. If so, the processing cannot be stopped.
　すなわち、処理の最初に比較的大きな電流を流すことで、大部分の白金族金属を剥離させ、その後定電圧による処理を行えば、金属基材の急激な溶解を防止しながら、短時間で白金族金属の剥離が可能になる。 That is, if a relatively large current is passed at the beginning of the treatment to peel off most of the platinum group metals, and then the treatment with a constant voltage is performed, platinum can be treated in a short time while preventing the metal substrate from being rapidly melted. The group metal can be peeled off.
　（実施例５）
　図６の結果は、被処理物である積層体に印加する電圧を変化させたということもできる。つまり、処理最初は高い電圧をかけ、処理後半は電圧を低くする様に電源を運転したことになる。 (Example 5)
It can also be said that the result of FIG. 6 changed the voltage applied to the laminated body as the object to be processed. In other words, the power supply was operated so that a high voltage was applied at the beginning of the processing and the voltage was lowered in the latter half of the processing.
　図７は、逆に処理の初期には電圧を低く、徐々に印加電圧を高めた場合の結果を示す。図７（ａ）は処理時間と電極間電流値（Ａ）の関係を表し、図７（ｂ）はその際に電極間に印加した電圧（Ｖ）と処理時間の関係を示したものである。 On the contrary, FIG. 7 shows the result when the voltage is low at the initial stage of the processing and the applied voltage is gradually increased. FIG. 7A shows the relationship between the processing time and the current value (A) between the electrodes, and FIG. 7B shows the relationship between the voltage (V) applied between the electrodes and the processing time. ..
　図７（ａ）では、横軸は（処理）時間（ｍｉｎ）であり、縦軸は電流（Ａ）である。図７（ｂ）では、横軸は（処理）時間（ｍｉｎ）であり、縦軸は電極間に印加した設定電圧（Ｖ）である。図７（ｂ）を参照して、ここでは、５分毎に印加電圧値を６Ｖ、７．３Ｖ、９Ｖ，９．７Ｖ、１１Ｖと高くしていった。１１Ｖ印加し３分経過後に電流値の減少が始まった。 In FIG. 7A, the horizontal axis is the (processing) time (min) and the vertical axis is the current (A). In FIG. 7B, the horizontal axis is the (processing) time (min), and the vertical axis is the set voltage (V) applied between the electrodes. With reference to FIG. 7B, here, the applied voltage values were increased to 6V, 7.3V, 9V, 9.7V, and 11V every 5 minutes. After 3 minutes had passed after applying 11V, the current value started to decrease.
　被処理物の白金族金属の膜厚が不明な場合は、一気に高電圧を印加すると、積層体（被処理物）表面の白金族金属の剥離より早く金属基材の溶解が始まる場合があり、ダメージの少ない金属基材の回収が困難となる。 If the film thickness of the platinum group metal of the object to be treated is unknown, if a high voltage is applied at once, the metal substrate may start melting earlier than the platinum group metal on the surface of the laminate (processed object) is peeled off. It becomes difficult to recover the metal base material with less damage.
　被処理物の白金族金属の膜厚が不明な場合は、本実施例のように、低い印加電圧から処理を始め、時間経過と共に印加電圧を上げる様にすると、白金族金属が徐々に剥離し、白金族金属の確実な回収と、痩せ細りのない金属基材の回収を行うことができる。 When the film thickness of the platinum group metal of the object to be treated is unknown, the platinum group metal gradually peels off when the treatment is started from a low applied voltage and the applied voltage is increased over time as in this embodiment. , Platinum group metal can be reliably recovered, and a metal base material without thinning can be recovered.
　なお、この場合も最後に印加した電圧は１１Ｖであり、この時流れた電流は、８．２Ａであった。したがって、処理を終了させる減少点は、７．４Ａ～５．７Ａとなる時間である。
　（実施例６）
　回収原料（積層体）は、電解めっきの陽極として使用されたメッシュ状のものを用いた。（実施例１で用いたものと同じものである。）回収原料に２質量体積％、１０質量体積％、２０質量体積％のフッ化水素を加え、３０分間放置した。いずれの場合も激しく水素が放出した。３０分経過後に回収原料を引き上げると、最初に黒色をしていたものが、銀色光沢を呈していた。また、黒色の粉末が沈殿していた。これより、チタン基材上に形成された白金族金属は２質量体積％以上のフッ化水素で全量剥離させることができることが分かった。 Also in this case, the voltage applied last was 11V, and the current flowing at this time was 8.2A. Therefore, the decrease point at which the processing is terminated is the time from 7.4A to 5.7A.
(Example 6)
As the recovered raw material (laminated body), a mesh-like material used as an anode for electrolytic plating was used. (It is the same as that used in Example 1.) Hydrogen fluoride of 2% by mass, 10% by mass and 20% by mass was added to the recovered raw material and left for 30 minutes. In each case, hydrogen was released violently. When the recovered raw material was pulled up after 30 minutes had passed, what was initially black had a silvery luster. In addition, black powder was precipitated. From this, it was found that the platinum group metal formed on the titanium substrate can be completely exfoliated with hydrogen fluoride of 2% by mass or more.
　なお、黒色粉末状の沈殿物を元素分析した結果を図８に示す。図８を参照して、横軸はフッ酸の濃度（質量体積％）を示し、縦軸は含有率（質量％）を示す。図１によれば、アルミニウム、チタン、イリジウム、白金、その他が検出された。これよりイリジウムの純度は２５質量％程度であることが分かった。 The result of elemental analysis of the black powdery precipitate is shown in FIG. With reference to FIG. 8, the horizontal axis shows the concentration of hydrofluoric acid (mass volume%), and the vertical axis shows the content rate (mass%). According to FIG. 1, aluminum, titanium, iridium, platinum, and others were detected. From this, it was found that the purity of iridium was about 25% by mass.
　（実施例７）
　５０ｃｍ３の容積を有する試験管に２．６質量体積％のフッ酸２０ｃｍ３と所定濃度の過酸化水素水を加え、その中に重さ０．２５ｇのチタン板を浸漬させた。試験管内にはスターラーも入れ、５００ｒｐｍの回転速度で試験管内部を攪拌した。試験管内の５０ｃｍ３の目盛りの位置で水素濃度を測定した。結果を図９に示す。 (Example 7)
To a test tube having a volume of 50 cm 3 , 2.6 mass by mass of hydrofluoric acid 20 cm 3 and a hydrogen peroxide solution having a predetermined concentration were added, and a titanium plate weighing 0.25 g was immersed therein. A stirrer was also placed in the test tube, and the inside of the test tube was stirred at a rotation speed of 500 rpm. The hydrogen concentration was measured at the position of the scale of 50 cm 3 in the test tube. The results are shown in FIG.
　図９を参照して、横軸は反応時間（ｍｉｎ）であり、縦軸は検出した水素濃度（ｐｐｍ）である。なお、縦軸は対数表示である。過酸化水素水は０質量体積％、１．６質量体積％、３．２質量体積％、６．３質量体積％の濃度で変化させた。その結果、過酸化水素水が入っていないときには、１００００ｐｐｍであった水素濃度が、６．３質量体積％の過酸化水素水を加えることで、１００ｐｐｍまで（１／１００まで）低下した。 With reference to FIG. 9, the horizontal axis is the reaction time (min) and the vertical axis is the detected hydrogen concentration (ppm). The vertical axis is a logarithmic display. The hydrogen peroxide solution was changed at concentrations of 0% by mass, 1.6% by mass, 3.2% by mass, and 6.3% by mass. As a result, the hydrogen concentration, which was 10,000 ppm when the hydrogen peroxide solution was not contained, was reduced to 100 ppm (to 1/100) by adding the hydrogen peroxide solution of 6.3% by mass by mass.
　本発明に係る回収方法は、金属基材上に白金族金属の層を形成した積層体から白金族金属および金属基材を回収する方法として好適に利用できる。 The recovery method according to the present invention can be suitably used as a method for recovering a platinum group metal and a metal base material from a laminate in which a platinum group metal layer is formed on a metal base material.
　１　　剥離装置
　１０　　剥離槽
　１０ｍ　　電解用溶液
　１２　　陰電極部
　１４　　陽電極部
　１６　　電源
　１６ａ　　定電圧源
　１６ｂ　　定電流源
　１６ｃ　　交流電源
　１６ｄ　　切換スイッチ
　１６ｅ　　電流計
　１６ｆ　　電圧計
　１８　　制御装置
　２２　　温度計
　２４　　ｐＨ計
　２６　　恒温装置
　２６ａ　　管
　５２　　陰極板
　５０　　積層体
　５０ａ　　白金族金属層
　５０ｂ　　金属基材 1 Peeling device 10 Peeling tank 10m Electrolytic solution 12 Negative electrode part 14 Positive electrode part 16 Power supply 16a Constant voltage source 16b Constant current source 16c AC power supply 16d Changeover switch 16e Ammeter 16f Voltmeter 18 Control device 22 Thermometer 24 pH meter 26 Constant temperature device 26a Tube 52 Electrode plate 50 Laminated body 50a Platinum group metal layer 50b Metal substrate

Claims (8)

  1. 　金属基材上に白金族金属の層が形成された積層体から前記白金族金属を回収する方法であって、
    　前記積層体と導電体を、フッ素を含む水溶液に浸漬する工程と、
    　前記積層体を陽極、前記導電体を陰極として、前記陽極と前記陰極の間に定電圧を印加する工程を有する白金族金属の回収方法。     A method for recovering the platinum group metal from a laminate in which a platinum group metal layer is formed on a metal substrate.
    The step of immersing the laminate and the conductor in an aqueous solution containing fluorine,
    A method for recovering a platinum group metal, which comprises a step of applying a constant voltage between the anode and the cathode, with the laminate as an anode and the conductor as a cathode.
  2. 　金属基材上に白金族金属の層が形成された積層体から前記白金族金属を回収する方法であって、
    　前記積層体と導電体を、フッ素を含む水溶液に浸漬する工程と、
    　前記積層体を陽極、前記導電体を陰極として、前記陽極と前記陰極の間に印加電圧の異なる複数の定電圧を順次印加する工程を有する白金族金属の回収方法。     A method for recovering the platinum group metal from a laminate in which a platinum group metal layer is formed on a metal substrate.
    The step of immersing the laminate and the conductor in an aqueous solution containing fluorine,
    A method for recovering a platinum group metal, which comprises a step of sequentially applying a plurality of constant voltages having different applied voltages between the anode and the cathode, with the laminate as an anode and the conductor as a cathode.
  3. 　前記陽極と前記陰極の間に流れる電流の減少点を検出した後に前記定電圧の印加を停止する請求項１または２の少なくとも一の請求項に記載の白金族金属の回収方法。 The method for recovering a platinum group metal according to claim 1 or 2, wherein the application of the constant voltage is stopped after the point of decrease in the current flowing between the anode and the cathode is detected.
  4. 　前記電流の減少点は、前記陽極と前記陰極間に最後に印加した電圧によって流れた電流の８０％乃至９０％になった点である請求項３に記載された白金族金属の回収方法。 The platinum group metal recovery method according to claim 3, wherein the point of decrease in the current is 80% to 90% of the current flowing due to the voltage last applied between the anode and the cathode.
  5. 　前記フッ素を含む水溶液のフッ素源が、フッ化物塩である請求項３に記載された白金族金属の回収方法。 The method for recovering a platinum group metal according to claim 3, wherein the fluorine source of the aqueous solution containing fluorine is a fluoride salt.
  6. 　前記金属基材がチタンである請求項３に記載された白金族金属の回収方法。 The method for recovering a platinum group metal according to claim 3, wherein the metal base material is titanium.
  7. 　前記フッ素を含む水溶液を一定温度に保持する工程を有する請求項３に記載された白金族金属の回収方法。 The method for recovering a platinum group metal according to claim 3, which comprises a step of holding the aqueous solution containing fluorine at a constant temperature.
  8. 　金属基材上に白金族金属の層が形成された積層体から前記白金族金属を回収する方法であって、
    　前記積層体を、フッ素および過酸化水素、または、硝酸を含む水溶液に浸漬する工程を有する白金族金属の回収方法。     A method for recovering the platinum group metal from a laminate in which a platinum group metal layer is formed on a metal substrate.
    A method for recovering a platinum group metal, which comprises a step of immersing the laminate in an aqueous solution containing fluorine, hydrogen peroxide, or nitric acid.
PCT/JP2021/048591 2020-12-25 2021-12-27 Method for recovering platinum-group metal WO2022138982A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4832252B1 (en) * 1969-02-12 1973-10-04
JPS5188424A (en) * 1975-02-01 1976-08-03 Kikinzokushokubaino kaishuhoho oyobi sonokaishuzai
JPS63270421A (en) * 1987-04-27 1988-11-08 Tanaka Kikinzoku Kogyo Kk Method for recovering platinum group metals from platinum group metallic oxide electrode
JPH07109594A (en) * 1991-12-26 1995-04-25 Sapporo Electro Pureiteingu Kogyo Kk Method for releasing gold or platinum-group coating metallic substrate and device therefor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4832252B1 (en) * 1969-02-12 1973-10-04
JPS5188424A (en) * 1975-02-01 1976-08-03 Kikinzokushokubaino kaishuhoho oyobi sonokaishuzai
JPS63270421A (en) * 1987-04-27 1988-11-08 Tanaka Kikinzoku Kogyo Kk Method for recovering platinum group metals from platinum group metallic oxide electrode
JPH07109594A (en) * 1991-12-26 1995-04-25 Sapporo Electro Pureiteingu Kogyo Kk Method for releasing gold or platinum-group coating metallic substrate and device therefor

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