JP5376558B2 - Precious metal recovery method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently recovering a noble metal without using acid having high oxidizing power. <P>SOLUTION: This invention relates to the method for recovering the noble metal from a base material containing the noble metal. The method includes: a step (S11) in which noble metal grains 12 on the base material 10 are subjected to chlorination treatment, so as to form a noble metal chloride; and a step (S20) in which the noble metal chloride or a compound containing the noble metal chloride is extracted from the base material 10. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for recovering a noble metal.

  When separating and recovering precious metals in scrap such as electronic materials and catalysts, using cyanide or mercury can selectively extract and separate the target precious metals, but at the same time, waste liquids and waste containing harmful substances It may occur in large quantities and pollute the environment. For this reason, a method has been conventionally used in which the entire scrap containing the precious metal is melted or pyrolyzed to extract and separate the target precious metal. This is because it is more chemically stable than scrap in which precious metals coexist, and it is difficult to selectively dissolve only precious metals in acid or the like. At present, when recovering from scrap containing a small amount of precious metal, existing methods such as leaching using a solution containing a cyanide compound, aqua regia, or chlorine gas may be used. There is a problem that a large amount of acid is required for the acid treatment, and at the same time, a large amount of waste liquid containing unusable metals and harmful compounds is generated.

On the other hand, a technique for recovering precious metals using copper, mercury, or the like as an extractant (collector metal) has been used for a long time. When a dry copper smelting process is available, copper can be used as an extractant because the precious metal in copper can be easily recovered. However, depending on the region and circumstances, the copper smelting process may not be used. Moreover, it is not preferable to use mercury as an extractant from the viewpoint of environmental conservation.
Therefore, the present inventors have already provided a method for separating a noble metal using active metal vapor as a method for recovering the noble metal without using a large amount of acid or a copper smelting process (see Patent Document 1).
JP 2003-247030 A

According to the recovery method described in Patent Document 1, the extraction efficiency of noble metal from scraps and the like can be greatly increased. However, the extraction uses an acid with strong oxidizing power such as aqua regia and requires a large amount of acid and oxidizing agent. Further, since this treatment generates a large amount of waste liquid containing a large amount of compounds other than noble metals, there remains a problem with this waste liquid treatment.
Accordingly, an object of the present invention is to provide a method for efficiently recovering a noble metal without using an acid having a strong oxidizing power.

  The noble metal recovery method of the present invention is a method of recovering the noble metal from a base material containing the noble metal, wherein the noble metal is one or more selected from Ca, Mg, Na, K, Li, Zn. A compound containing a noble metal chloride and a chloride of the active metal by reacting with an active metal that is a metal to form an alloy, and supplying a chlorine gas to the noble metal alloy on the base material to perform chlorination And a step of extracting the noble metal chloride from the base material.
  The noble metal recovery method of the present invention is a method of recovering the noble metal from a base material containing the noble metal, wherein the noble metal is one or more selected from Ca, Mg, Na, K, Li, Zn. Reacting with an active metal that is a metal to form an alloy, and heating and chlorinating a mixture of the base material containing the noble metal alloy and a chlorinating agent, thereby precious metal chloride and chloride of the active metal. And a step of forming a compound including the step of extracting the noble metal chloride from the base material.
  The noble metal recovery method of the present invention is a method of recovering Pt from a substrate containing Pt, and the Pt on the substrate is one or two selected from Ca, Mg, Na, K, Li, Zn A step of reacting with an active metal which is the above metal to form an alloy, and a Pt alloy on the base material is subjected to chlorination treatment using chlorine gas or a chlorinating agent, whereby Pt chloride and the chloride of the active metal are obtained. In the step of immersing the base material in an acid, the step of immersing the base material in an acid, and in the step of immersing in the acid, Pt contained in the base material using an acid containing no oxidizing agent as the acid It is characterized by dissolving 80% or more.
  The method for recovering a noble metal of the present invention is a method for recovering a noble metal from a substrate containing any one of Pd, Rh, Ru, Ir, Os or two or more kinds of noble metals, wherein the noble metal on the substrate is Ca, A step of reacting with an active metal which is one or more metals selected from Mg, Na, K, Li, and Zn, and alloying the precious metal alloy on the substrate with chlorine gas or a chlorinating agent; A step of forming a compound containing the noble metal chloride and the active metal chloride by chlorination; and a step of immersing the base material in an acid. In the step of immersing in the acid, 80% or more of the noble metal contained in the base material is dissolved using an acid containing no oxidizing agent as the acid.

  In this recovery method, prior to extraction of the noble metal from the base material, the noble metal on the base material is chlorinated to form a noble metal chloride, whereby an acid such as hydrochloric acid that does not contain a strong oxidizing agent. Also made it possible to extract precious metals. Thereby, the extraction process can be completed in a short time, and generation of waste liquid that is difficult to process can be avoided. In addition, since noble metals in scrap are often dispersed in a minute amount on a substrate having a complicated structure, when a gas phase (gas) is used during chlorination, the noble metal can be uniformly chlorinated, It has the feature that scrap can be processed efficiently.

  The step of chlorinating the noble metal is preferably a step of supplying the chlorine gas to the noble metal to produce the noble metal compound. Chlorine gas may be supplied to the reaction system from the outside, or may be generated from a metal chloride or the like in the reaction system.

  It is preferable that the step of chlorinating the noble metal is a step of heating a mixture of the base material containing the noble metal and a chlorinating agent. With such a method, the chlorinating agent can be directly applied to the noble metal, the chlorination reaction of the noble metal can be promoted, and the noble metal chloride can be efficiently generated. Depending on the reaction conditions, a chlorinating agent or a compound containing a chlorinating agent can be directly reacted with the noble metal in a liquid or solid state, and the method of heating the above mixture includes such a form. It is out.

The chlorinating agent is preferably CuCl ₂ or FeCl ₃ , a lower chloride thereof, or a double salt (composite chloride) containing these chlorides.
These metal chlorides can function as a chlorinating agent for chlorinating Pt to produce platinum chloride such as PtCl ₂ or a double salt thereof. In addition, since the decomposition temperature is relatively low, by disposing these metal chlorides in the same reaction system, chlorine gas or chlorinating agent vapor can be generated. The reaction can also proceed.

Prior to the step of chlorinating the noble metal, it is preferable to have a step of reacting the noble metal with an active metal to form an alloy.
Thus, by forming the noble metal alloy prior to the chlorination treatment step, the acid solubility can be dramatically improved. This is thought to be because the active metal constituting the noble metal alloy is preferentially salified in the chlorination treatment process to make the noble metal alloy porous, thereby increasing the surface area of the noble metal in contact with the collector and acid in the extraction process. It is done. Therefore, according to the present invention, the extraction efficiency of the noble metal can be greatly improved.

  The active metal is preferably one or more metals selected from Ca, Mg, Na, K, Li, and Zn. Since these active metals have high affinity with noble metals and high vapor pressure, the noble metals can be efficiently alloyed.

  The step of alloying the noble metal is preferably a gas phase reaction step of reacting the noble metal on the substrate with the active metal in the gas phase atmosphere of the active metal. By using the gas phase reaction, the active metal can be contacted uniformly and quickly with a base material or noble metal having a complicated shape, and the noble metal can be efficiently alloyed.

  The step of extracting the noble metal chloride preferably includes a step of leaching the noble metal chloride from the base material with an acid. The step of extracting the noble metal chloride preferably includes a noble metal recovery step using a dry treatment method (more specifically, the Yamamoto reduction or the Rose method). That is, in the present invention, a known wet or dry extraction process can be applied to the extraction step.

The step of extracting the noble metal chloride includes a first recovery step of recovering the noble metal by leaching the noble metal chloride from the base material with an acid, and a dry treatment method (copper smelting or refining after the first recovery step) And a second recovery step of recovering the noble metal using a known smelting method such as a rose method.
With such a recovery method, the precious metal can be roughly removed in the first recovery step, and the precious metal that cannot be recovered in the first recovery step can be recovered in the second recovery step. Thereby, a noble metal is recoverable with a high recovery rate.

  It is preferable that the noble metal is any one of Pt, Pd, Rh, Ru, Ir, Os, or two or more. That is, the present invention is a recovery method suitable for recycling platinum group metals.

  The noble metal recovery method of the present invention is a method for recovering the noble metal from a base material containing a noble metal, the step of reacting the noble metal on the base material with an active metal to form an alloy, and the above-mentioned noble metal on the base material. A step of forming a compound containing a noble metal chloride by chlorinating a noble metal alloy; and a step of immersing the base material in an acid. The step of immersing in the acid is included in the base material. The noble metal is dissolved in an acid. According to this recovery method, an acid in which the noble metal is dissolved can be obtained by immersing the substrate, and the subsequent purification of the noble metal can be performed easily and quickly.

  The noble metal recovery method of the present invention is a method for recovering Pt from a substrate containing Pt, the step of reacting Pt on the substrate with an active metal to form an alloy, and the Pt alloy on the substrate A step of forming a compound containing Pt chloride by chlorinating and a step of immersing the base material in an acid. In the step of immersing in the acid, an acid containing no oxidizing agent as the acid 80% or more of Pt contained in the base material is dissolved using According to this recovery method, Pt can be recovered extremely efficiently from a base material such as scrap.

  A method of recovering from any of Pd, Rh, Ru, Ir, Os or a base material containing two or more kinds of noble metals, and reacting the noble metal on the base material with an active metal to form an alloy. And a step of forming a compound containing the noble metal chloride by chlorinating the noble metal alloy on the base material, and a step of immersing the base material in an acid. 80% or more of the noble metal contained in the base material is dissolved using an acid containing no oxidizing agent as the acid. That is, the above recovery method can be suitably used for recovering platinum group noble metals other than Pt.

  The acid containing no oxidizing agent is preferably hydrochloric acid. By using hydrochloric acid as the acid for extracting the noble metal, the noble metal can be extracted efficiently. In addition, the cost of waste liquid treatment can be reduced.

  According to the recovery method of the present invention, prior to extracting the noble metal from the substrate, the noble metal on the substrate is chlorinated to form a noble metal chloride, such as hydrochloric acid not containing a strong oxidizing agent. The extraction of precious metals can be performed even with acids. Thereby, the extraction process can be completed in a short time, and generation of waste liquid that is difficult to process can be avoided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional process diagram illustrating an embodiment of a noble metal recovery method according to the present invention, and FIG. 2 is a flowchart illustrating the steps of two types of recovery methods according to the present invention. FIG. 3 is a flowchart showing three aspects of the process of extracting the noble metal from the base material.

  The method for recovering a noble metal of the present invention includes a first mode shown in FIG. 2 (a) and a second mode shown in FIG. 2 (b). The 1st aspect shown to Fig.2 (a) is the collection | recovery method which has alloying process S10, chlorination process S11, and extraction process S20. On the other hand, the 2nd aspect shown in FIG.2 (b) is a collection | recovery method which has chlorination process S11 and extraction process S20. Furthermore, any of the extraction steps (1) to (3) shown in FIG. 3 can be used as the extraction step S20 shown in FIG.

  First, of the recovery methods according to the present invention, the procedure for recovering the noble metal particles 12 supported on the substrate 10 shown in FIG. 1A by the recovery method of the first aspect shown in FIG. explain.

  A substrate 10 shown in FIG. 1A conceptually shows a noble metal supporting portion such as a catalyst of an automobile or the like, an electronic device part, a decorative article, and the like. Further, FIG. 1A illustrates the case where the particulate noble metal particles 12 are supported on the base material 10, but even if the noble metal has a planar shape (film shape), the structure is complicated and complicated. (For example, a porous body of an insulating material) may be used. The noble metal particles 12 that can be effectively recovered by this recovery method are Au, Ag, Pt, Rh, Pd, Ir, Ru, Os, or an alloy thereof.

  In order to recover the noble metal particles 12 from the base material 10 by the recovery method according to the present invention, first, as shown in FIG. 1B, the base material 10 is introduced into the active metal vapor 13 (alloying step S10). .

The active metal vapor can be generated by heating the metal vapor source to a high temperature in the reaction chamber. As the metal vapor source, metals such as Mg, Ca, Zn, Fe, Na, K, Pb, and Li can be used. Alternatively, those oxides, carbides, and those added with carbon or the like as necessary may be used. For example, as a metal vapor source, a mixture of zinc oxide (such as ZnO), iron, sodium oxide (Na ₂ O), and carbon can be used, and metals that generate Zn vapor, Fe vapor, and Na vapor, respectively. Functions as a steam source.

Then, the above-mentioned metal vapor source is introduced into the reaction chamber together with the base material 10 which is the object to be processed, and the base material 10 is easily exposed to the atmosphere of the active metal vapor 13 by setting the reaction chamber to about 500 to 1600K. Can do. By this step, as shown in FIG. 1B, an active metal deposit 13a is formed on the substrate 10, and the noble metal particles 12 on the substrate 10 react with the active metal vapor 13 to react with the noble metal alloy. 12a.
The alloying step S10 is not limited to the alloying process using a gas phase reaction. Depending on the form of the noble metal particles 12, the active metal solid or liquid and the noble metal particles 12 are brought into direct contact with each other. The noble metal particles 12 may be alloyed by reacting.

In the recovery method according to the present invention, an active metal vapor 13 capable of selectively forming a compound with the noble metal particles 12 is used when producing the noble metal alloy 12a. That is, the active metal vapor 13, typically catalyst support in which alumina _(Al 2 _{O 3)} or mullite _{(3Al 2 O 3 · 2SiO 2} ), cordierite _{(2MgO · 2Al 2 O 3 ·} 5SiO in the catalyst of an automobile ₂ ) Almost no reaction with oxides contained in, etc., and selectively forms a compound (for example, MgPt, MgRh, etc.) with Pt, Pd, Rh, etc. supported on the carrier.
The metals used for alloying are the active metals listed above in that they have high chemical affinity with noble metals and are difficult to react with the base material 10 carrying the noble metal particles 12. It is preferable to use it, but any metal having a vapor pressure of 10 ⁻⁴ atm or more and capable of forming a noble metal alloy is applicable.

Next, as shown in FIG.1 (c), the base material 10 in which the noble metal alloy 12a was formed is introduce | transduced in the chlorinating agent vapor | steam 14 (chlorination process process S11).
For example, the chlorinating agent vapor source and the base material 10 are introduced into the reaction chamber, and the reaction chamber is set to about 500 to 1600 K, whereby the chlorinating agent vapor 14 is generated from the chlorinating agent vapor source and brought into contact with the base material 10. Thus, the noble metal alloy 12a and the chlorinating agent vapor | steam 14 are contacted, and the compound 12b containing a noble metal chloride is formed on the base material 10. FIG. Further, the active metal deposit 13a on the substrate 10 becomes active metal chloride 13b by the chlorinating agent.

As the chlorinating agent vapor 14, vapor of metal chloride such as CuCl ₂ or Fe ₂ Cl ₆ (FeCl ₃ ) can be used in addition to chlorine gas. Also, double salts (composite chlorides) in which these metal chlorides are combined with other chlorides can be used. The chlorine gas may be directly supplied from the outside, or may be supplied to the substrate 10 from a chlorinating agent vapor source (CuCl ₂ , FeCl _3, etc.) disposed in the reaction chamber.
In the recovery method according to the present invention, in the chlorination treatment step S11, a mixture of the base material 10 on which the noble metal alloy 12a is formed and a chlorinating agent (CuCl ₂ , FeCl ₃ etc.) is installed in the reaction chamber, By maintaining the temperature (500 to 1600 K), the chlorinating agent and the noble metal alloy 12 a can be reacted directly.

  Further, when the noble metal is recovered by the second mode shown in FIG. 2B, the alloying step S10 in the first mode described above is omitted. That is, in the present invention, the alloying step S10 is not essential. According to the second aspect, the noble metal particles 12 on the base material 10 are not alloyed with the active metal, and the noble metal particles 12 on the base material 10 react with the chlorinating agent vapor in the chlorination treatment step S11 to react with the noble metal chloride. Or it becomes a compound containing a noble metal chloride.

If the precious metal chloride or the compound 12b containing the precious metal chloride is formed on the base material 10 by the above steps, the precious metal chloride or the precious metal chloride is removed from the base material 10 by subjecting it to the dry or wet extraction step S20. The compound 12b containing is separated and recovered.
Various existing extraction processes can be used as the extraction step S20. Specifically, as shown in FIG. 3, any one of (1) dry extraction step S22, (2) wet extraction step S21, and (3) an extraction step combining wet extraction step S21 and dry extraction step S22. Can be used.

  The wet extraction step S21 is a step of leaching the noble metal chloride formed on the base material 10 or the compound 12b containing the noble metal chloride from the base material 10 with an acid. Acids such as hydrochloric acid, nitric acid and aqua regia can be used as the acid. Depending on the conditions, the leaching treatment can be performed by combining these acids and chlorine gas. In the present invention, the noble metal particles 12 are chlorinated prior to the extraction step to increase the chlorine potential of the noble metal, so that noble metal chloride or a compound 12b containing noble metal chloride can be obtained even with hydrochloric acid having weak oxidizing power. It is possible to extract. Further, if the acid used in the wet extraction step is heated to 300K or more, the leaching of the compound 12b containing the noble metal chloride is promoted, and the treatment in a shorter time becomes possible. The temperature of the acid is desirably increased within a range where no trouble occurs, more preferably 320K or more, and further preferably 350K or more.

As described above, according to the recovery method of the first aspect in which the alloying step S10 is performed prior to the chlorination treatment step S11, the solubility of the compound 12b containing the noble metal chloride in hydrochloric acid can be dramatically increased. . That is, according to the recovery method of the first aspect, typically a Pt which can not dissolve unless a strong acid containing a strong oxidizing agent such as nitric acid and Cl _2, was readily dissolved in the hydrochloric acid containing no oxidizing agent Be able to.
This is because, in the chlorination treatment step S11, the active metal (Mg or the like) constituting the compound 12b containing the noble metal chloride is preferentially salified to make the noble metal porous, and the reaction area related to chlorination of the noble metal increases. This is probably because the chlorination of the noble metal proceeds more efficiently.

The dry extraction step S22 uses a melt of copper, nickel, iron, lead or the like as a collector to extract and separate a noble metal into a metal phase. As dry extraction process S22, well-known methods, such as a Yamamoto reduction and the Rose method, can be used. Copper alloys containing noble metals obtained in these extraction processes are separated and recovered by ordinary metal smelting (refining) methods centering on wet methods, and finally high purity noble metals alone or their compounds Is obtained.
In particular, the present invention has an advantage in that it is possible to recover a precious metal that is easily oxidized such as Ru, which has been recovered by a conventional method in which scrap containing precious metal is directly put into a dry extraction process and has not been efficiently recovered. Have That is, in the conventional method, Ru that is oxidized at a high temperature cannot be recovered because it is transferred to slag or dust. However, in the recovery method of the present invention, Ru is in an alloyed or chlorinated state. Since it is used for the extraction process, it is concentrated in the collector together with other precious metals without shifting to slag or dust, and can be efficiently separated and recovered.

  Further, in the present invention, as shown in FIG. 3 (3), the base material 10 containing the noble metal chloride or the compound 12b containing the noble metal chloride is first subjected to the wet extraction step S21 to roughen the noble metal, and then The noble metal remaining on the substrate 10 can also be extracted by subjecting it to the dry extraction step S22. By adopting such an extraction method, the precious metal can be quickly recovered by the wet extraction step S21, and further, the precious metal can be recovered without waste by the dry extraction step S22 having a high recovery rate.

  Through the extraction steps (1) to (3) described above, the noble metal particles 12 can be selectively and efficiently extracted from the base material 10 as shown in FIG. And a noble metal can be collect | recovered by using for the collection | recovery and refinement process S23, such as a solvent extraction method, the alloy and noble metal compound containing the noble metal obtained by the process of (1)-(3).

  As described above in detail, according to the recovery method of the present invention, the noble metal chloride on the base material 10 is obtained by subjecting the noble metal particles 12 on the base material 10 to chlorination prior to the extraction step S20. Alternatively, the compound 12b containing a noble metal chloride is formed. Thereby, the extraction efficiency of the noble metal in subsequent extraction process S20 can be improved greatly. Therefore, the problem of the processing speed in the conventional wet method can be solved.

  Further, according to the present invention, the chlorine potential of the noble metal can be increased by the chlorination treatment, whereby the noble metal chloride or the compound 12b containing the noble metal chloride can be dissolved in hydrochloric acid not containing a strong oxidizing agent. . In particular, when the compound 12b containing a noble metal chloride is formed by the alloying step S10 and the chlorination treatment step S11, the dissolution rate with respect to hydrochloric acid is dramatically improved. Therefore, it is not necessary to use poisons such as acids and cyanide compounds containing a strong oxidizing agent in the wet extraction process, and the waste liquid can be treated normally. Thus, the present invention is an environment-friendly noble metal recovery method in which a noble metal that is difficult to dissolve by a conventional method is processed so as to be efficiently dissolved in an acid by pretreatment.

In addition, in the conventional recovery method in which scrap is directly put into the metal phase, there is a problem that a precious metal such as Ru that is easily oxidized at a high temperature is transferred to slag or dust as an oxide, and the recovery rate is lowered. In the recovery method in which the acid is directly added, there are problems that Ru is not completely dissolved and the recovery rate is low, and a large amount of harmful waste liquid containing a large amount of heavy metals is generated. On the other hand, in the recovery method according to the present invention, Ru chloride (RuCl _x ) or a compound containing Ru chloride (MgRu _x Cl prior to the extraction step S20) even when the object to be treated such as scrap contains Ru. _y , CuRu _x Cl _y , FeRu _x Cl _y, etc.) are formed on the base material 10 and these chlorides are separated from the base material 10 in the extraction step S20. And is efficiently recovered.

In the present invention, CuCl ₂ or FeCl ₃ is used as the chlorinating agent in the chlorination treatment step S11. These metal chlorides are currently treated as industrial waste. For example, CuCl ₂ is a main component of the copper etching waste liquid of the printed circuit board, and FeCl ₃ is contained in the waste liquid in the pickling process of steel and the etching process of semiconductor. Furthermore, since chlorination smelting methods such as titanium smelting and silicon smelting will develop in the future and the amount of chloride waste such as FeCl ₃ will increase, these chloride wastes will be used effectively as chlorinating agents. You can also. In the present invention, since these chloride wastes are effectively used as a chlorinating agent, there is a possibility that it can contribute to effective use, weight reduction, and detoxification of chloride waste, which is currently costly and problematic. There is.

FIG. 4 is a diagram showing an example of a recovery apparatus that can carry out the recovery method according to the present invention.
The recovery apparatus 100 includes an introduction unit 101, an alloying processing unit 102, a chlorination processing unit 103, and a discharge unit 104 on a transport mechanism 110, and a compound containing a noble metal chloride taken out from the discharge unit 104. One or both of the wet extraction unit 105 and the dry extraction unit 106 that perform the extraction process are provided.
The alloying processing unit 102 includes a reaction chamber filled with active metal vapor. The chlorination unit 103 includes a reaction chamber filled with a vapor of a chlorinating agent. The wet extraction unit 105 includes an acid treatment tank. The dry-type extraction unit 106 includes a high-temperature furnace in which a collector metal melt is accommodated.

  In the recovery apparatus 100, when an object to be processed such as crushed scrap is placed in the introduction unit 101, the object to be processed is transferred to the alloying processing unit 102 by the transfer mechanism 110, and first alloyed. Thereafter, the paper is transported to the chlorination unit 103 by the transport mechanism 110 and subjected to chlorination. The alloying processing unit 102 and the chlorination processing unit 103 are not necessarily performed by physically different processing units, and can be sequentially performed in the same apparatus depending on conditions and operation methods. As a result, the object to be processed in which the noble metal particles become a compound containing noble metal chloride is discharged to the discharge unit 104. And the precious metal can be extracted to an acid and a collector by throwing in the processed material taken out from the discharge unit 104 sequentially into either or both of the wet extraction unit 105 and the dry extraction unit 106.

  As described above, in the recovery device 100 shown in FIG. 4, since the scrap is vapor-phase processed before the wet extraction unit 105 or the dry extraction unit 106, even a scrap having a complicated shape is uniformly and quickly preprocessed. It can be performed. In addition, since an object to be processed can be continuously processed, it is possible to easily cope with an increase in process size.

Hereinafter, the verification results of the present invention will be described in detail by way of examples.
FIG. 5 is a schematic diagram of an experimental apparatus used for chlorination of a noble metal (pure Pt) and a noble metal alloy (Mg—Pt alloy). The experimental apparatus shown in FIG. 5 includes one or a plurality of quartz crucibles containing a sample, a quartz tube containing the quartz crucible inside, and an electric furnace for heating the quartz tube from the outside.

(Chloride treatment using gas phase reaction)
First, the chlorination treatment of pure Pt and Mg—Pt alloy using a gas phase reaction will be described.
In this example, CuCl ₂ was used as a chlorinating agent vapor source. In the chlorination treatment, pure Pt and Mg—Pt alloy solid powders were treated via the gas phase without being brought into physical contact with CuCl ₂ . More details are as follows.
Three quartz crucibles each containing Mg—Pt alloy, pure Pt (comparative sample), and CuCl ₂ (chlorinating agent vapor source) were prepared. The above three quartz crucibles were placed near the closed end of the quartz tube and filled with glass wool to prevent dissipation of powder and vaporized sample. Thereafter, the inside of the quartz tube is depressurized, and maintained at a plurality of temperature conditions (673K, 773K, 873K) for 3 hours using an electric furnace, and chlorination treatment of Mg—Pt alloy and pure Pt with chlorine gas generated from CuCl _2. Went.

  In addition, the Mg-Pt alloy used for said chlorination process prepared the uniform alloy in order to confirm the reproducibility of the processing method and the effect. Specifically, 1-2 g of Mg pieces and 4-8 g of Pt sample are placed in a tantalum crucible, and held in a sealed reaction vessel held at 1173 K for 12 hours, so that the inside of the tantalum crucible It was produced by alloying Mg and Pt. In actual operation, Mg vapor and Pt may be reacted at a high temperature for synthesis. In addition to Mg, alloying elements such as Ca, Na, K, Li, and Zn may be used. The obtained Mg—Pt alloy was pulverized into a powder form and subjected to chlorination treatment with pure Pt powder having the same particle size.

  Next, the chlorinated sample was dissolved in 10 M hydrochloric acid, and the acid solubility of Pt was evaluated from the Pt concentration in the obtained aqueous solution. For comparison, pure Pt powder and Mg—Pt alloy before chlorination treatment (untreated) were also dissolved in 10M hydrochloric acid. The acid dissolution condition was performed by putting a sample of 0.05 g to 0.1 g into 45 ml of 10 M hydrochloric acid held at 353 K and holding it for 15 minutes. Undissolved residue was filtered off by suction filtration using filter paper. The obtained filtrate was prepared to 100 ml using ion-exchanged water.

  The compound phase of the sample obtained by the experiment was identified using a powder X-ray diffractometer (XRD). The sample subjected to the chlorination treatment was subjected to XRD measurement by protecting the sample with parafilm in order to prevent reaction with moisture in the air. The surface morphology of the sample was observed using a scanning electron microscope (SEM), and the qualitative analysis was performed using an energy dispersive X-ray spectrometer (EDS) and a fluorescent X-ray analyzer (XRF). Further, after dissolving 0.05 g of the sample in 40 ml of aqua regia, quantitative analysis of the element concentration in the solution was performed using an inductively coupled plasma atomic emission spectrometer (ICP-AES).

FIG. 6 is an XRD diffraction pattern of pure Pt powder after chlorination treatment. For comparison, the XRD diffraction pattern of PtCl ₂ is also shown in FIG.
As shown in FIG. 6, in the sample with a processing temperature of 773 K, a peak of PtCl ₂ was confirmed together with a peak of pure Pt. On the other hand, only the peak of pure Pt was observed in the samples with treatment temperatures of 673K and 873K. In addition, Cl was detected by XRF analysis from a sample at a processing temperature of 773 K, and it was confirmed by SEM and EDS analysis that Cl and Pt were distributed in the same region. From these results, it is presumed that in the gas phase reaction at the treatment temperature of 773 K, the Pt chlorination reaction proceeded by the chlorine gas generated by the decomposition of CuCl ₂ and the Pt chloride was generated.

FIG. 7 is a graph showing the dissolution rate of pure Pt powder that has been chlorinated using a gas phase reaction with hydrochloric acid.
As shown in FIG. 7, pure Pt powder before chlorination treatment hardly dissolved in hydrochloric acid, whereas Pt powder chlorinated at 673K and 773K dissolved in hydrochloric acid. From this, it was confirmed that the chlorination treatment by gas phase reaction at 673K and 773K contributes to the improvement of the acid solubility of Pt. Further, the sample subjected to the chlorination treatment at 773 K showed the highest acid solubility. Since the production of PtCl ₂ was confirmed in the XRD diffraction pattern of the sample treated with 773K, it is considered that the Pt chlorination reaction proceeds most under the same conditions. Normally, Pt cannot be dissolved unless a strong acid containing a strong oxidizing agent such as nitric acid or Cl ₂ is used, and Pt hardly dissolves in hydrochloric acid containing no oxidizing agent. However, it should be noted that using this method, Pt can be dissolved in a solution using only hydrochloric acid.

Next, FIG. 8 is an XRD diffraction pattern of the Mg—Pt alloy after the chlorination treatment. For comparison, the XRD diffraction patterns of PtCl ₂ and parafilm are also shown in FIG.
As shown in FIG. 8, in addition to the diffraction peaks of pure Pt and MgCl _2, a diffraction peak considered to be PtCl ₂ was observed from the sample at a treatment temperature of 773 K. In addition, diffraction peaks of pure Pt and MgCl ₂ were observed in samples with other temperature conditions.
This suggests that the Pt chlorination reaction progressed in the sample at a treatment temperature of 773 K, and Pt chloride was synthesized. On the other hand, MgCl ₂ was produced in any sample because the standard production Gibbs energy of MgCl ₂ (−517 kJ at 773 K) was much smaller than the standard production Gibbs energy of PtCl ₂ (−75.5 kJ at 773 K). From this, it can be explained that Mg was preferentially salified over Pt.

For the Mg—Pt alloy, an acid dissolution experiment was performed before and after the chlorination treatment. The Mg—Pt alloy before the treatment hardly dissolved in hydrochloric acid, whereas in the samples chlorinated with 673K and 773K, 1 to 5% of Pt was dissolved in hydrochloric acid. From this, it was confirmed that the chlorination treatment by gas phase reaction at 673K and 773K is effective for improving the acid solubility of Pt. The solubility in hydrochloric acid was highest in the sample chlorinated with 773K, and in the sample chlorinated with 773K, the production of PtCl ₂ was confirmed in the XRD diffraction pattern, and in the Mg-Pt alloy, the Pt content was the same. It is considered that the chlorination reaction proceeds most.

(Chlorination treatment using mixed reaction)
Next, the chlorination treatment of pure Pt and Mg—Pt alloy using a mixed reaction will be described.
In this example, as shown in FIG. 5, CuCl ₂ was used as a chlorinating agent vapor source, and chlorination treatment was performed in a state where CuCl ₂ and solid powder of pure Pt or Mg—Pt alloy were mixed. More specifically, a quartz crucible containing Mg—Pt alloy and CuCl ₂ (chlorinating agent vapor source) and a quartz crucible containing pure Pt (comparative sample) and CuCl ₂ were prepared. The chlorination treatment was performed in the same manner as in the case of using the gas phase reaction. That is, one of the quartz crucibles is arranged near the closed end of the quartz tube, filled with glass wool for preventing the dissipation of powder and vaporized sample, and then the inside of the quartz tube is evacuated and a plurality of electric furnaces are used. The Mg—Pt alloy and pure Pt were subjected to chlorination treatment with CuCl ₂ by maintaining at the temperature conditions (673K, 773K, 873K) for 3 hours.

  Further, the chlorinated sample was dissolved in 10M hydrochloric acid, and the acid solubility of Pt was evaluated from the Pt concentration in the obtained aqueous solution. For comparison, pure Pt powder and Mg—Pt alloy before chlorination treatment (untreated) were also dissolved in 10M hydrochloric acid. The conditions for acid dissolution are the same as those described above.

About the sample obtained by experiment, identification of the compound phase was performed using the powder X-ray-diffraction apparatus (XRD). FIG. 9 is an XRD diffraction pattern of pure Pt powder after chlorination treatment by a mixing reaction. For comparison, the XRD diffraction pattern of PtCl ₂ is also shown in FIG.
As shown in FIG. 9, in the sample chlorinated with 773K, the diffraction peak of PtCl ₂ and CuCl was confirmed together with the diffraction peak of pure Pt, and the chlorination treatment of Pt progressed by the chlorination treatment by the mixed reaction. It was confirmed that was synthesized.

FIG. 10 is a diagram showing the XRD diffraction pattern of the Mg—Pt alloy after the chlorination treatment by the mixing reaction together with the XRD diffraction pattern of the Mg—Pt alloy by the gas phase reaction.
As shown in FIG. 10, the diffraction peaks of PtCl ₂ , MgCl ₂ , and CuCl were confirmed in the sample chlorinated with 773 K, and the chlorination of Pt proceeded by the chlorination treatment by the mixed reaction even in the Mg—Pt alloy. It was confirmed that the chloride was synthesized. In particular, in the sample of the Mg—Pt alloy subjected to the chlorination treatment by the mixed reaction, the Pt diffraction peak disappears after the chlorination treatment, and it is considered that Pt was more efficiently chlorinated by the chlorination treatment in the mixed reaction.

As shown in FIGS. 9 and 10, a CuCl diffraction peak was confirmed from any sample treated with pure Pt powder and Mg—Pt alloy. From this, it is considered that in the mixed reaction using CuCl ₂ as a chlorinating agent, CuCl ₂ directly acts on the chlorination treatment of Pt, and PtCl ₂ and CuCl were generated.

  Next, FIG. 11 shows the dissolution rate of Pt of a sample obtained by chlorination of pure Pt powder by a mixing reaction, the dissolution rate of pure Pt powder before chlorination treatment, and the Pt of a sample obtained by chlorination of pure Pt powder by a gas phase reaction. It is a figure shown with the dissolution rate. The dissolution rate of each sample was measured by performing a dissolution treatment using hydrochloric acid containing no oxidizing agent under the same conditions shown in FIG. FIG. 12 shows the dissolution rate of Pt in a sample obtained by chlorination of pure Pt powder and Mg—Pt alloy by a gas phase reaction, and the dissolution rate of Pt in a sample obtained by chlorination of pure Pt powder and Mg—Pt alloy by a mixing reaction. FIG.

  As shown in FIG. 11, in the sample in which pure Pt powder was chlorinated by a mixed reaction, the dissolution rate of Pt in hydrochloric acid in a sample in which pure Pt powder was chlorinated by a gas phase reaction was about 1%. Thus, a dissolution rate of about 20% was obtained. In addition, as shown in FIG. 12, in the Mg—Pt alloy that was chlorinated by a mixed reaction, 100% of Pt was dissolved in hydrochloric acid. Normally, hydrochloric acid containing no oxidizing agent cannot dissolve Pt. However, it has been found that hydrochloric acid can be used to dissolve 100% of Pt depending on conditions if the treatment method of the present invention is used. This implementation result is a notable point and is one of the elemental technologies of the present invention. As is clear from FIG. 12, the pure Pt powder and the Mg—Pt alloy were compared with each other in terms of the amount dissolved in hydrochloric acid of the sample chlorinated by the gas phase reaction and the mixed reaction at 773K. This showed higher acid solubility of Pt than the sample treated by the gas phase reaction.

Here, FIG. 13 is a chemical potential diagram of the Pt—Cu—Cl ₂ system at 773K. Assuming that CuCl ₂ is thermodynamically unstable at 773K and CuCl ₂ directly acts on Pt chlorination in the mixing reaction, the reaction of PtCl ₂ and CuCl by the reaction of Pt and CuCl ₂ (described below) _{p Cl2} as a driving force of the formula (1)) is obtained with virtually 18atm standard reaction Gibbs energy of the formula (2).

2CuCl ₂ (s) + Pt (s) → 2CuCl (s) + PtCl ₂ (s)… (1)
2CuCl ₂ (s) = 2CuCl (s, l) + Cl ₂ … (2)

On the other hand, _{pCl2, which} is the driving force of the reaction shown in the following formula (3) in the gas phase reaction, is that of chlorine gas generated from the reaction of the formula (2), and is 1 atm at maximum in the reactor shown in FIG. It is.

Pt (s) + Cl ₂ (g) → PtCl ₂ (s)… (3)

Accordingly, as shown in FIG. 13, CuCl ₂ is higher _{p Cl2} than gas phase reactions which acts as a Cl ₂ gas chlorinating agent generated by mixing the decomposition towards reaction CuCl ₂ acting on chloride directly Pt, Since the driving force of the reaction shown in Formula (3) is large, it is considered that the chloride reaction of Pt proceeded efficiently and the chloride was synthesized.

Sectional process drawing which shows one Embodiment of the collection | recovery method of the noble metal which concerns on this invention. The flowchart which each shows the process of two types of collection | recovery methods which concern on this invention. The flowchart which shows three aspects of the process of extracting a noble metal from a base material. The figure which shows an example of the collection | recovery apparatus which can implement the collection | recovery method concerning this invention. Schematic of the experimental apparatus used for chlorination treatment. XRD diffraction pattern of pure Pt powder after chlorination treatment. The figure which shows the melt | dissolution rate of the pure Pt powder chloride-processed using the gas phase reaction. The XRD diffraction pattern of the Mg-Pt alloy after a chlorination process. XRD diffraction pattern of pure Pt powder after chlorination treatment by mixed reaction. The XRD diffraction pattern of the Mg-Pt alloy after the chlorination process by mixed reaction. The figure which compared the dissolution rate of Pt of a mixed reaction and a gaseous-phase reaction. The figure which compared the dissolution rate of Pt with a pure Pt powder and a Mg-Pt alloy. The chemical potential figure of Pt-Cu-Cl system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Base material, 12 Noble metal particle, 12a Noble metal alloy, 12b Compound containing noble metal chloride, 13 Active metal vapor | steam, 13a Deposit, 13b Active metal chloride, 14 Chlorinating agent vapor | steam, 101 Introducing part, 102 Alloying process part, 103 Chlorination treatment part, 104 Discharge part, 105 Wet extraction part, 106 Dry extraction part

Claims (11)

A method for recovering the noble metal from a base material containing the noble metal,
Reacting the noble metal with an active metal which is one or more metals selected from Ca, Mg, Na, K, Li, and Zn, and alloying them;
Forming a compound containing a noble metal chloride and a chloride of the active metal by supplying a chlorine gas to the noble metal alloy on the substrate and subjecting it to chlorination ; and
Extracting the noble metal chloride from the substrate;
A method for recovering a noble metal, comprising: A method for recovering the noble metal from a base material containing the noble metal,
Reacting the noble metal with an active metal which is one or more metals selected from Ca, Mg, Na, K, Li, and Zn, and alloying them;
Forming a compound containing a noble metal chloride and a chloride of the active metal by heating and chlorinating a mixture of the base material containing the noble metal alloy and a chlorinating agent;
Extracting the noble metal chloride from the substrate;
A method for recovering a noble metal, comprising: The method for recovering a noble metal according to claim 2 , wherein the chlorinating agent is CuCl ₂ or FeCl ₃ , a lower chloride thereof, or a composite chloride containing these chlorides. The process of alloying the noble metal is a gas phase reaction process of reacting the noble metal on the substrate with the active metal in a gas phase atmosphere of the active metal . The method for recovering a precious metal according to any one of the above items . The method for recovering a noble metal according to any one of claims 1 to 4, wherein the step of extracting the noble metal chloride includes a step of leaching the noble metal chloride from the base material with an acid. The method for recovering a noble metal according to any one of claims 1 to 4, wherein the step of extracting the noble metal chloride includes a noble metal recovery step using a dry processing method. The step of extracting the noble metal chloride includes a first recovery step of recovering the noble metal chloride by leaching the noble metal chloride from the substrate with an acid, and further using a dry treatment method after the first recovery step. The method for recovering a noble metal according to any one of claims 1 to 4, further comprising a second recovery step of recovering the noble metal from a base material. The method for recovering a noble metal according to any one of claims 1 to 7 , wherein the noble metal is any one of Pt, Pd, Rh, Ru, Ir, and Os, or two or more thereof. A method of recovering Pt from a substrate containing Pt,
Reacting Pt on the substrate with an active metal which is one or more metals selected from Ca, Mg, Na, K, Li, Zn and alloying;
Forming a compound containing Pt chloride and a chloride of the active metal by subjecting the Pt alloy on the substrate to chlorination treatment using chlorine gas or a chlorinating agent ;
Immersing the base material in an acid,
In the step of immersing in the acid, 80% or more of Pt contained in the base material is dissolved using an acid containing no oxidizing agent as the acid. A method of recovering a noble metal from a base material containing any one of Pd, Rh, Ru, Ir, Os or two or more kinds of noble metals,
Reacting a noble metal on the substrate with an active metal that is one or more metals selected from Ca, Mg, Na, K, Li, Zn , and alloying;
Forming a compound containing the noble metal chloride and the active metal chloride by chlorinating the noble metal alloy on the substrate using chlorine gas or a chlorinating agent ;
Immersing the base material in an acid,
In the step of immersing in the acid, 80% or more of the noble metal contained in the base material is dissolved using an acid containing no oxidizing agent as the acid. The method for recovering a noble metal according to claim 9 or 10 , wherein the acid containing no oxidizing agent is hydrochloric acid.

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