JP2019127627A - Method for recovering noble metal - Google Patents

Abstract

To provide a method of recovering a noble metal that can recover a noble metal efficiently and conveniently.SOLUTION: A method for recovering a noble metal, has a step (I) of preparing a noble metal-containing material, a solid oxidizer, and an acid solution and a step (II) of putting the noble metal-containing material and solid oxidizer into the acid solution for a reaction of the noble metal-containing material at 80°C or higher.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method of recovering precious metals.

  There is a high need for technology for recovering precious metals from materials such as waste materials containing precious metals (hereinafter referred to as “precious metal-containing materials”).

  As such a precious metal recovery technique, a process for extracting precious metal ions has been performed so far by putting a precious metal-containing material into an acid such as aqua regia and separating and purifying the precious metal from the resulting solution. I came.

  However, such a method is difficult to say that it is a sufficiently sophisticated process.

  For example, nitric acid contained in aqua regia may hinder the subsequent separation and purification process of noble metals. In particular, in the separation and purification step by the solvent extraction method, the extractant of the noble metal may be deteriorated by nitric acid, which may lower the extraction rate of the noble metal. In order to avoid this, after the dissolution of the precious metal-containing material by aqua regia, a step of removing nitric acid (denitrification step) is separately required.

  Then, in order to cope with such a problem, a new precious metal recovery method is proposed. For example, Patent Document 1 proposes a method in which chlorine gas is passed into hydrochloric acid to which a platinum-containing material is added to elute platinum. Patent Document 2 proposes a method of dissolving a material containing platinum in a hydrochloric acid solution containing hydrogen peroxide solution.

Japanese Patent Laid-Open No. 9-324223 JP-A-9-263847

  As mentioned above, in recent years, various precious metal recovery methods have been proposed. However, in these processes, it can not be said that precious metals can be recovered efficiently and easily.

  For example, in the method described in Patent Document 1, chlorine gas is introduced into hydrochloric acid as an oxidizing agent for oxidizing platinum. However, the time for which chlorine gas stays in hydrochloric acid is not so long, so it is difficult to increase the probability of chlorine gas coming into contact with platinum in hydrochloric acid. Therefore, there is a problem that it is difficult to increase the elution rate of platinum.

  Further, in the method described in Patent Document 2, the bubbling of oxygen occurs during the decomposition of hydrogen peroxide, which may cause the volume of the hydrochloric acid solution to rapidly increase. Therefore, in the method described in Patent Document 2, attention must be paid to handling of the reaction apparatus and safety measures, and the process may be complicated.

  This invention is made | formed in view of such a background, and this invention aims at providing the collection | recovery method of a noble metal which can collect | recover a noble metal more efficiently and simply than before.

In the present invention, a method for recovering noble metals,
(I) preparing a noble metal-containing material, a solid oxidizing agent, and an acid solution;
(II) introducing the noble metal-containing material and the solid oxidizing agent into the acid solution and reacting the noble metal-containing material at a temperature of 80 ° C. or higher;
A method is provided.

Further, in the present invention, a method for recovering a noble metal,
(III) preparing a noble metal-containing material, a solid oxidizing agent, and an acid solution;
(IV) adding the acid solution and the solid oxidizing agent to the noble metal-containing material, and reacting the noble metal-containing material at a temperature of 80 ° C. or higher;
A method is provided.

  In the present invention, it is possible to provide a method for recovering a noble metal capable of recovering the noble metal more efficiently and simply than before.

FIG. 5 shows the standard redox potentials of several ions and compounds. FIG. 5 schematically shows a flow of a method of recovering a noble metal according to an embodiment of the present invention. FIG. 5 schematically shows a flow of a method of recovering a noble metal according to another embodiment of the present invention. It is the graph which showed collectively the precious metal dissolution rate obtained in Examples 1-5 and Examples 21-25. It is the graph which put together and showed the noble metal dissolution rate obtained in Examples 6-15. It is the graph which put together and showed the noble metal dissolution rate obtained in Examples 31-33, and Examples 41-43. It is the graph which put together and showed the noble metal dissolution rate obtained in Example 34- Example 35 and Example 44-45.

  Hereinafter, an embodiment of the present invention will be described.

In one embodiment of the invention:
A method for recovering precious metals,
(I) preparing a noble metal-containing material, a solid oxidizing agent, and an acid solution;
(II) introducing the noble metal-containing material and the solid oxidizing agent into the acid solution and reacting the noble metal-containing material at a temperature of 80 ° C. or higher;
A method is provided.

  Here, the “solid oxidant” oxidizes the noble metal contained in the noble metal-containing material (hereinafter referred to as “direct oxidation”) or oxidizes the noble metal by a reaction product generated by the reaction with the acid solution. (Hereinafter referred to as “indirect oxidation”).

Hereinafter, characteristics of a method according to an embodiment of the present invention (hereinafter referred to as “the noble metal recovery process of the present invention”) will be described. Here, the precious metal recovery process of the present invention is exemplified here in the case where the precious metal contained in the precious metal-containing material is platinum (Pt), the solid oxidizing agent is cerium oxide (CeO ₂ ), and the acid solution is hydrochloric acid. Will be explained.

  In the noble metal recovery process of the present invention, in the step (II), the noble metal-containing material and cerium oxide are introduced into the hydrochloric acid solution.

Cerium oxide functions as a solid oxidizing agent for the aforementioned "indirect oxidation". That is, cerium oxide generates chlorine gas in hydrochloric acid by the reaction of the following formula (1):

₂ CeO ₂ +8 HCl → ₂ CeCl ₃ + Cl ₂ + 4H ₂ O (1)

Chlorine gas in hydrochloric acid acts as an oxidant of platinum contained in the noble metal-containing material. That is, platinum is oxidized by the following formula (2):

Pt + 2Cl ₂ → Pt ⁴⁺ + 4Cl ⁻ (2) formula

Oxidized platinum is rapidly complexed and eluted into hydrochloric acid according to the following formula (3):

Pt ⁴⁺ + 6Cl ⁻ → [PtCl ₆ ] ²⁻ (3)

Thereafter, the eluted complex ions of platinum are separated and recovered from the hydrochloric acid.

  Through such a process, platinum can be recovered from the noble metal-containing material.

  Here, in the method in which chlorine gas as an oxidizing agent is passed through hydrochloric acid as in the above-mentioned Patent Document 1, the time for which chlorine gas stays in hydrochloric acid is short, and therefore, chlorine gas comes into contact with platinum in hydrochloric acid. It is difficult to increase the probability. Therefore, it is difficult to increase the elution rate of platinum.

  On the other hand, in the noble metal recovery process of the present invention, the noble metal oxidation step represented by the formula (2) can be controlled by a solid oxidizing agent. That is, by controlling the timing of addition of the solid oxidant, the amount of addition, the temperature of the reaction field (that is, the acid solution), etc., the time for which the chlorine produced by the formula (1) is in contact with the noble metal is made longer. be able to.

  As a result, in the noble metal recovery process of the present invention, it becomes possible to elute the noble metal into the acid solution more efficiently than before. Thereby, the noble metal can be efficiently recovered.

  Further, in the precious metal recovery process of the present invention, a chlorine gas supply facility or the like is not necessary, and the precious metal can be recovered easily by a relatively simple method.

  Figure 1 shows the standard redox potentials of several ions and noble metals.

From FIG. 1, the standard oxidation-reduction potential of platinum is 1.18 V (hereinafter referred to as “Ev (Pt)”). On the other hand, between tetravalent cerium ion (Ce ⁴⁺ ) and trivalent cerium ion (Ce ³⁺ ), between tetravalent manganese ion (Mn ⁴⁺ ) and divalent manganese ion (Mn ²⁺ ), and HSO ₅ ⁻ The standard oxidation-reduction potential between ions and HSO ₄ ⁻ ions is higher than Ev (Pt). Therefore, it can be seen that Ce ⁴⁺ ion, Mn ⁴⁺ ion, and HSO ₅ ⁻ ion can oxidize platinum.

Note that the standard oxidation-reduction potential between pentavalent vanadium ions (V ⁵⁺ ) and tetravalent vanadium ions (V ⁴⁺ ) is 0.991 V, which is lower than Ev (Pt). However, in the case of vanadium, further reduction from tetravalent vanadium ion (V ⁴⁺ ) to trivalent vanadium ion (V ³⁺ ) is possible, and by combining them, higher standard oxidation than Ev (Pt) is possible. The reduction potential is obtained. Therefore, platinum can be oxidized using pentavalent vanadium ion (V 5 ⁺ ).

  For example, the standard oxidation-reduction potentials of palladium and rhodium are 0.951 V and 0.76, respectively, which are lower than Ev (Pt).

  Accordingly, it is understood that palladium and rhodium are more easily oxidized than platinum, and if it is a solid oxidizing agent containing the aforementioned ions capable of oxidizing platinum, palladium and rhodium can also be oxidized.

From the above, at least a tetravalent cerium ion (Ce ⁴⁺ ), a tetravalent manganese ion (Mn ⁴⁺ ), and a pentavalent vanadium ion (V ⁵⁺ ) as solid oxidizing agents usable for the precious metal recovery process of the present invention And HSO ₅ ⁻ ions can be mentioned.

  The above-mentioned precious metal recovery process of the present invention has a step of charging a precious metal-containing material and a solid oxidizing agent into an acid solution. However, differently from this, it is known to those skilled in the art that the same effect as the above-described noble metal recovery process of the present invention can be obtained even by using a method in which a solid oxidizing agent and an acid solution are added to a noble metal-containing material. It will be clear.

(Method for recovering noble metals according to an embodiment of the present invention)
Next, with reference to FIG. 2, a method of recovering a noble metal according to an embodiment of the present invention will be described.

  FIG. 2 schematically shows a flow of a method (hereinafter referred to as “first method”) for recovering a noble metal according to an embodiment of the present invention.

As shown in FIG. 2, the first method is:
Preparing a noble metal-containing material, a solid oxidizing agent, and an acid solution (step S110);
Introducing the noble metal-containing material and the solid oxidizing agent into the acid solution and reacting the noble metal-containing material at a temperature of 80 ° C. or higher (step S120);
Have.

  Hereinafter, each step will be described.

(Step S110)
First, a noble metal-containing material, a solid oxidizing agent, and an acid solution are prepared. Each of these will be described below.

(Precious metal containing material)
The noble metal-containing material contains a noble metal to be recovered in the first method.

  The noble metal contained in the noble metal-containing material includes at least one selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), and ruthenium (Ru). The noble metal may be a single metal or an alloy.

  When the noble metal is an alloy, examples of the noble metal include Pt—Ir alloys (for example, used for spark plugs for gasoline engines), Pt—Rh alloys (for example, used for thermocouples), Pt—Ru. Alloys (eg, used in fuel cell catalysts), Pd—Au alloys (eg, used in dental crowns) and the like are included.

  The noble metal-containing material may be composed of a noble metal and other elements. Precious metal-containing materials include, for example, magnetic recording materials containing Pt—Fe alloys, magnetic bits for hard disks containing Pt—Co—Cr alloys and Co—Cr—Pt—Ru alloys, and hydrogen separation membranes containing Pd—Cu alloys, etc. It may be.

  The noble metal-containing material may be in any form. The noble metal-containing material may be, for example, in the form of a plate, a block, a mesh, a wire, or a powder.

  When the precious metal-containing material is a large-sized heavy material, the precious metal-containing material may be subjected to various pretreatments such as cutting, pulverizing, and / or rolling. In particular, it is preferable to perform a pretreatment that increases the specific surface area, such as miniaturization and / or ball milling, on the noble metal-containing material. By increasing the specific surface area of the noble metal-containing material, various reactions in subsequent steps can be promoted.

(Acid solution)
The acid solution is selected from those capable of dissolving the noble metal in the noble metal-containing material in combination with a solid oxidizing agent described later. The acid solution may be, for example, at least one selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, phosphoric acid, formic acid, and acetic acid. These acids may be mixed as necessary.

  The concentration of the acid contained in the acid solution is not particularly limited as long as the noble metal in the noble metal-containing material can be sufficiently dissolved. The concentration of the acid is, for example, in the range of 0.1 M to 15 M.

  For example, when the acid solution contains hydrochloric acid, the concentration of hydrochloric acid may be 1M (dilute hydrochloric acid) or 12M (concentrated hydrochloric acid). For example, when the acid solution contains nitric acid, the concentration of nitric acid may be 1M or 15M (concentrated nitric acid).

  The acid concentration is preferably in the range of 1M to 15M, more preferably in the range of 3M to 12M.

(Solid oxidizer)
As described above, the solid oxidizing agent has a role of oxidizing the noble metal contained in the noble metal-containing material or oxidizing the noble metal by a reaction product generated by the reaction with the acid solution.

The solid oxidizer is
It is selected from (a) a compound containing a specific cation, or (b) a compound containing a specific anion. Specific cations in (a) may include, for example, cerium ions (Ce ⁴⁺ ), manganese ions (Mn ⁴⁺ ), and vanadium ions (V ⁵⁺ ). Moreover, the specific anion of (b) may be a persulfate ion (HSO ₅ ⁻ ).

In the case of (a), the solid oxidant is in the form of an oxide, hydroxide, chloride, nitrate, sulfide, sulfate, fluoride, phosphate, and / or acetate, for example. Also good. The solid oxidizing agent is particularly preferably in the form of an oxide such as cerium oxide (CeO ₂ ), manganese oxide (MnO ₂ ), and vanadium oxide (V ₂ O ₅ ).

Cerium oxide (CeO ₂ ) is a compound contained in used abrasive grains and the like. Manganese oxide (MnO ₂ ) is a compound included in a used battery. Therefore, these solid oxidizing agents can be procured at low cost, and the cost of the first manufacturing method can be suppressed.

In the case of (b), the solid oxidizing agent is preferably in the form of a persulfate such as MHSO ₅ . Here, M is, for example, an alkali metal ion such as sodium ion (Na ⁺ ) and / or potassium ion (K ⁺ ), or ammonium ion (NH ₄ ⁺ ).

  The form of the solid oxidizing agent is not particularly limited. The solid oxidizing agent may be in a powder form, for example.

(Step S120)
Next, a noble metal-containing material and a solid oxidizing agent are introduced into the acid solution.

  The noble metal-containing material and the solid oxidizing agent may be introduced into the acid solution substantially simultaneously. Alternatively, the solid oxidizing agent may be introduced after introducing the noble metal-containing material into the acid solution.

  Alternatively, the noble metal-containing material and the solid oxidizing agent may be mixed in advance and introduced into the acid solution in the form of a mixture. In such a method, when the solid oxidizing agent functions as the oxidizing agent for the above-mentioned “direct oxidation”, the noble metal contained in the noble metal-containing material is oxidized when the noble metal-containing material and the solid oxidizing agent are mixed. it can.

For example, our findings suggest that KHSO ₅ can "directly oxidize" platinum.

  The amount of solid oxidizing agent added to the acid solution is not particularly limited as long as a sufficient amount of noble metal can be eluted.

  However, the solid oxidizing agent is consumed by the oxidation reaction of the noble metal and / or the reaction with the acid solution. For this reason, it is preferable to add a solid oxidizing agent more than the amount required for these reactions.

For example, when the solid oxidizing agent is cerium oxide (CeO ₂ ), the acid solution is hydrochloric acid, and the noble metal is platinum, as described above, in order to oxidize platinum, 2 moles of Cl ₂ is required for about 195 g). Therefore, from formula (1), 4 moles (about 688 g) of cerium oxide is required.

  In the same system, when the amount of hydrochloric acid required is determined, 16 mol of hydrochloric acid is required for 4 mol of cerium oxide from the equation (1). Further, from the equations (2) and (3), a total of 2 moles of hydrochloric acid is required to complex ionize platinum. That is, a total of 18 moles of hydrochloric acid are required. This corresponds to about 1.5 liters for a hydrochloric acid concentration of 12M.

On the other hand, when the solid oxidizing agent is cerium oxide (CeO ₂ ), the acid solution is hydrochloric acid, and the noble metal is palladium (Pd), it is considered as follows.

First, cerium oxide generates an oxidant (Cl ₂ ) as in the above-mentioned equation (1):

₂ CeO ₂ +8 HCl → ₂ CeCl ₃ + Cl ₂ + 4H ₂ O (1)

Oxidation of palladium proceeds with the following equation (4):

Pd + Cl ₂ → Pd ²⁺ + 2Cl ⁻ (4) Formula

Also, the oxidized palladium is rapidly complex ionized by the following formula (5) and eluted in hydrochloric acid:

Pd ²⁺ + 4Cl ⁻ → [PdCl ₄ ] ²⁻ (5)

Therefore, in this system, 1 mol of Cl ₂ is required for 1 mol of palladium (about 106 g) to oxidize palladium. Therefore, from formula (1), 2 moles (about 344 g) of cerium oxide is required.

  Further, when the necessary amount of hydrochloric acid is determined, 8 moles of hydrochloric acid are required for 2 moles of cerium oxide from the equation (1). Further, due to the addition and subtraction of the equations (4) and (5), two moles of hydrochloric acid are required for complex ionization of palladium. That is, a total of 10 moles of hydrochloric acid are required. This corresponds to about 0.83 liters for a concentration of 12 M hydrochloric acid.

Furthermore, when the solid oxidizing agent is cerium oxide (CeO ₂ ), the acid solution is hydrochloric acid, and the noble metal is rhodium (Rh), it is considered as follows.

First, cerium oxide generates an oxidant (Cl ₂ ) as in the above-mentioned equation (1):

₂ CeO ₂ +8 HCl → ₂ CeCl ₃ + Cl ₂ + 4H ₂ O (1)

The oxidation of rhodium proceeds with the following equation (6):

₂ Rh ^{+ 3} Cl ₂ → ₂ Rh ³ + + 6 Cl ⁻ (6)

Oxidized rhodium is rapidly complexed and eluted into hydrochloric acid according to the following formula (7):

Rh ³⁺ + 5Cl ⁻ → [RhCl ₅ ] ²⁻ (7)

Therefore, in this system, to oxidize rhodium, 1.5 moles of Cl ₂ is required per 1 mole (about 103 g) of rhodium. Therefore, from formula (1), 3 moles (about 516 g) of cerium oxide is required.

  Further, when the necessary amount of hydrochloric acid is determined, 12 moles of hydrochloric acid are required for 3 moles of cerium oxide from the equation (1). Further, due to the addition and subtraction of the equations (6) and (7), two moles of hydrochloric acid are required for complex ionizing rhodium. That is, a total of 14 moles of hydrochloric acid are required. This corresponds to about 1.17 liters for a concentration of 12 M hydrochloric acid.

Furthermore, when the solid oxidizing agent is cerium oxide (CeO ₂ ), the acid solution is hydrochloric acid, and the noble metal is iridium (Ir), it is considered as follows.

First, cerium oxide generates an oxidant (Cl ₂ ) as in the above-mentioned equation (1):

₂ CeO ₂ +8 HCl → ₂ CeCl ₃ + Cl ₂ + 4H ₂ O (1)

The oxidation of iridium proceeds according to the following formula (8):

Ir + 2Cl ₂ → Ir ⁴⁺ + 4Cl ⁻ (8) Formula

Also, oxidized iridium is rapidly complex ionized by the following equation (9) and eluted in hydrochloric acid:

Ir ⁴ + + 6Cl ⁻ → [IrCl ₆ ] ²⁻ (9)

Therefore, in this system, 2 moles of Cl ₂ is necessary to 1 mole of iridium (about 192 g) to oxidize iridium. Therefore, from formula (1), 4 moles (about 688 g) of cerium oxide is required.

  Further, when the necessary amount of hydrochloric acid is determined, from the formula (1), 16 moles of hydrochloric acid is required for 4 moles of cerium oxide. Further, due to the addition and subtraction of the equations (8) and (9), two moles of hydrochloric acid are required for complex ionization of iridium. That is, a total of 18 moles of hydrochloric acid are required. This corresponds to about 1.5 liters for a hydrochloric acid concentration of 12M.

Further, when the solid oxidizing agent is cerium oxide (CeO ₂ ), the acid solution is hydrochloric acid, and the noble metal is ruthenium (Ru), it is considered as follows.

First, cerium oxide generates an oxidant (Cl ₂ ) as in the above-mentioned equation (1):

₂ CeO ₂ +8 HCl → ₂ CeCl ₃ + Cl ₂ + 4H ₂ O (1)

Ruthenium oxidation proceeds according to the following formula (10):

Ru + 2Cl ₂ → Ru ⁴⁺ + 4Cl ⁻ (10) Formula

Also, oxidized ruthenium is rapidly complex ionized by the following equation (11) and eluted in hydrochloric acid:

Ru ⁴ + + ₆ Cl ⁻ → [Ru Cl ₆ ] ^2- (11)

Therefore, in this system, 2 moles of Cl ₂ is necessary to 1 mole of ruthenium (about 101 g) to oxidize ruthenium. Therefore, from formula (1), 4 moles (about 688 g) of cerium oxide is required.

  Further, when the necessary amount of hydrochloric acid is determined, from the formula (1), 16 moles of hydrochloric acid is required for 4 moles of cerium oxide. Further, due to the addition and subtraction of the equations (10) and (11), two moles of hydrochloric acid are required for complex ionizing ruthenium. That is, a total of 18 moles of hydrochloric acid are required. This corresponds to about 1.5 liters for a hydrochloric acid concentration of 12M.

  In such a manner, the necessary amount of precious metal-containing material, solid oxidant and acid solution may be calculated.

  In particular, when the amount of the precious metal contained in the precious metal-containing material is known and the equivalent amount of the solid oxidant capable of eluting all the precious metals is defined as 1, the amount of the solid oxidant actually introduced is 1 equivalent. It may be in the range of ˜100 equivalents. The amount of the solid oxidizing agent is preferably in the range of 5 equivalents to 80 equivalents, more preferably in the range of 10 equivalents to 50 equivalents, and most preferably in the range of 20 equivalents to 45 equivalents.

  In addition, when the quantity of the noble metal contained in a noble metal containing material is unknown, it is difficult to perform such a calculation.

  In that case, it is necessary to determine the introduction amount of the solid oxidizing agent from the weight of the noble metal-containing material. In this case, the amount of the solid oxidant introduced is, for example, in the range of 10 wt% to 5000 wt%, preferably in the range of 25 wt% to 2500 wt%, more preferably 50 wt% to 2000 wt% with respect to the noble metal-containing material. % Range, more preferably 100% by weight to 1000% by weight.

  If the amount of solid oxidizing agent is too low, it will be difficult to sufficiently elute the precious metal. On the other hand, when there is too much quantity of a solid oxidizing agent, possibility that a part of solid oxidizing agent will not be used for reaction will become high.

  In addition, a dissolution aid may be further added to the acid solution. By adding a solubilizer, elution of the noble metal contained in the noble metal-containing material can be further accelerated.

  Examples of the dissolution aid include those capable of forming complex ions with noble metal ions. For example, chlorides, nitrates, sulfides, sulfates, fluorides, phosphates, and the like can generate anions in an acid solution, thereby promoting a complex ionization reaction of noble metals.

  By using a solubilizer, complex ionization reaction of noble metal can be promoted even when the concentration of the acid solution is low.

  By adding a noble metal-containing material and a solid oxidizing agent capable of “indirect oxidation” to the acid solution, a product generated by reaction with the acid solution is generated in the vicinity of the noble metal-containing material. Such oxidation reaction of noble metals can be caused. In addition, when the solid oxidizing agent has a "direct oxidation" function, the noble metal can be oxidized by directly contacting the noble metal-containing material with the solid oxidizing agent.

  Thereafter, the oxidized noble metal is rapidly complex ionized by a complex ionization reaction. Thereby, the noble metal can be eluted from the noble metal-containing material in the acid solution.

  The temperature of the acid solution serving as a reaction field is 80 ° C. or higher. The temperature of the acid solution is preferably 100 ° C. or more, more preferably 120 ° C. or more, and still more preferably 160 ° C. or more.

  If the treatment temperature is too high, the eluted noble metal ions may be reduced and deposited. Therefore, the treatment temperature is preferably 400 ° C. or less, more preferably 300 ° C. or less, and still more preferably 250 ° C. or less.

  Since concentrated sulfuric acid has a relatively high boiling point of 337 ° C., the processing temperature can be set higher than when other acid solutions are used. When concentrated sulfuric acid is used, the treatment temperature can be, for example, in the range of 350 ° C to 400 ° C.

  In addition, the treatment time is not particularly limited as long as the noble metal can be sufficiently eluted. The treatment time is, for example, in the range of 30 minutes to 24 hours, preferably in the range of 1 hour to 12 hours, and more preferably in the range of 2 hours to 6 hours.

  In order to make elution of the noble metal more efficient, the acid solution may be stirred or vibration may be applied to the acid solution. The method of stirring and shaking is not particularly limited, and for example, stirring with a stirring blade or a shaker may be used.

  Here, the reaction vessel used in step S120 is not particularly limited. However, it is preferable to use a sealable reaction vessel as the reaction vessel.

  In this case, evaporation of the acid solution and escape of the oxidizing agent can be significantly suppressed, and the noble metal can be eluted more efficiently.

  For example, in the example shown to above-mentioned (1) Formula, chlorine is produced | generated as an oxidizing agent by reaction of a solid oxidizing agent and an acid solution. This chlorine is preferably kept in the reaction system as much as possible. When a sealed container is used, this chlorine can be significantly suppressed from escaping out of the system.

  For example, the elution amount of the noble metal is 10% by mass or more of the total noble metal content contained in the noble metal-containing material, preferably 20% by mass or more, more preferably 30% by mass or more, and 50% by mass or more. More preferably.

  After the elution reaction of the noble metal sufficiently proceeds, the eluted noble metal is separated and recovered. The separation and recovery method of the noble metal is not particularly limited, and a conventional method may be adopted.

  In particular, in the first method, since noble metal complex ions are to be collected, the noble metal can be separated and extracted by a solvent extraction method, an ion exchange resin method, a precipitation method, or the like.

  According to the above steps, the noble metal can be efficiently recovered from the noble metal-containing material.

(Method for recovering precious metals according to another embodiment of the present invention)
Next, with reference to FIG. 3, a method of recovering a noble metal according to another embodiment of the present invention will be described.

  FIG. 3 schematically shows the flow of a method (hereinafter, referred to as “second method”) of recovering a noble metal according to another embodiment of the present invention.

As shown in FIG. 3, the second method is:
Preparing a noble metal-containing material, a solid oxidizing agent, and an acid solution (step S210);
Adding the acid solution and the solid oxidizing agent to the noble metal-containing material, and reacting the noble metal-containing material in the acid solution at a temperature of 80 ° C. or higher (step S220);
Have.

  Here, step S210 in the second method is substantially the same as step S110 in the first method described above. Therefore, description of step S210 is abbreviate | omitted here and step S220 is demonstrated.

(Step S220)
In the second method, in step S220, an acid solution and a solid oxidizing agent are added to the noble metal-containing material.

  The acid solution and the solid oxidizing agent may be added to the noble metal-containing material substantially simultaneously. Alternatively, the solid oxidizing agent may be introduced after adding the acid solution to the noble metal-containing material. Alternatively, the acid solution may be introduced after adding the solid oxidizing agent to the noble metal-containing material.

  In particular, the noble metal-containing material and the solid oxidizing agent may be mixed in advance, and an acid solution may be added to this mixture. In such a method, when the solid oxidizing agent functions as the oxidizing agent for the above-mentioned “direct oxidation”, the noble metal contained in the noble metal-containing material is oxidized when the noble metal-containing material and the solid oxidizing agent are mixed. Can do.

  Step S220 is performed at a temperature of 80 ° C. or more (hereinafter, this temperature is referred to as “processing temperature”). Thus, for example, an acid solution heated to 80 ° C. or higher may be added to the noble metal-containing material (and a solid oxidant, if present). Alternatively, the acid solution may be heated to 80 ° C. or higher with the noble metal-containing material (and the solid oxidizing agent, if present) immersed in the acid solution. If a solid oxidant has not yet been introduced, a solid oxidant may be added to the hot acid solution.

  The treatment temperature is preferably 100 ° C. or more, more preferably 120 ° C. or more, and still more preferably 160 ° C. or more.

  If the treatment temperature is too high, the eluted noble metal ions may be reduced and deposited. Therefore, the treatment temperature is preferably 400 ° C. or less, more preferably 300 ° C. or less, and still more preferably 250 ° C. or less.

  The treatment time is not particularly limited as long as the noble metal can be sufficiently eluted. The treatment time is, for example, in the range of 30 minutes to 24 hours, preferably in the range of 1 hour to 12 hours, and more preferably in the range of 2 hours to 6 hours.

  For other conditions, reference can be made to step S210 in the first method described above.

  The acid solution and the solid oxidizing agent are added to the noble metal-containing material, and after the noble metal elution reaction sufficiently proceeds, the noble metal is separated and recovered from the acid solution.

  The precious metal can be recovered from the precious metal-containing material by the above steps.

  Also in the second method, the same effect as the first method, that is, the effect that the noble metal can be eluted into the acid solution more simply and efficiently than in the conventional method can be obtained. Also, this makes it possible to recover the noble metal conveniently and efficiently.

  Examples of the present invention will be described below.

(Example 1)
10 mL of 12M hydrochloric acid, 25 mg of platinum powder, and 1.0 g of CeO ₂ powder were put into an inner cylinder container (volume: 25 mL) made of polytetrafluoroethylene (PTFE). The inner cylinder was mounted on a stainless outer container (Sanai Kagaku Co., Ltd., HU-25) and sealed. Then, the inner cylinder container and the outer cylinder container were hold | maintained at 180 degreeC for 2 hours.

  Next, the inner cylinder container was taken out from the outer cylinder container. Moreover, the solution contained in the inner cylinder container was filtered under reduced pressure using a PTFE filter, and separated into a solid and a liquid (hereinafter referred to as “separation liquid”).

In Example 1, no solid (residue) was observed. That is, the introduced platinum and CeO ₂ completely dissolved.

  Therefore, in Example 1, the dissolution rate of the noble metal (platinum) was 100%.

  In the present application, the dissolution rate of the precious metal is expressed as a percentage of (weight of dissolved precious metal) / (weight of administered precious metal).

(Example 2)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 2, the inner cylinder container and the outer cylinder container were held at 180 ° C. for 1 hour. Other conditions are the same as in Example 1.

  Noble metal concentrations in the separated liquid were measured using inductively coupled plasma emission spectroscopy (ICP-AES). Moreover, the dissolution rate of the noble metal was calculated from the obtained results.

  As a result, in Example 2, the dissolution rate of the noble metal was 96.9%.

(Example 3)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 3, the inner cylinder container and the outer cylinder container were maintained at 180 ° C. for 30 minutes. Other conditions are the same as in Example 1.

  In the same manner as in Example 2, the dissolution rate of the noble metal was calculated.

  As a result, in Example 3, the dissolution rate of the noble metal was 82.9%.

(Example 4)
20 mL of 12 M hydrochloric acid, 25 mg of platinum powder, and 1.0 g of CeO ₂ powder were charged into a conical flask (volume 50 mL). A condenser was attached to the top of the flask. The flask was immersed in a water bath maintained at 80 ° C., and held for 6 hours while stirring with a stirrer (200 rpm).

  Next, the solution contained in the flask was filtered under reduced pressure using a PTFE filter to separate the solid and the liquid.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 4, the dissolution rate of the noble metal was 12.4%.

(Example 5)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in Example 5, the amount of hydrochloric acid to be administered was 20 mL, and the inner cylinder container and the outer cylinder container were held at 80 ° C. for 6 hours. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 5, the dissolution rate of the noble metal was 47.4%.

(Example 6)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 6, the solid oxidizing agent to be administered was MnO ₂ . Other conditions are the same as in Example 1.

  The solution contained in the inner cylinder container was filtered under reduced pressure to separate it into a solid and a liquid.

  As a result, in Example 6, no solid (residue) was observed. That is, the introduced platinum was completely dissolved.

  Therefore, in Example 6, the dissolution rate of the noble metal (platinum) was 100%.

(Example 7)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 7, the solid oxidizing agent to be administered was V ₂ O ₅ . Other conditions are the same as in Example 1.

  The solution contained in the inner cylinder container was filtered under reduced pressure to separate it into a solid and a liquid.

  As a result, in Example 7, no solid (residue) was observed. That is, the introduced platinum was completely dissolved.

  Therefore, in Example 7, the dissolution rate of the noble metal (platinum) was 100%.

(Example 8)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this Example 8, it was KHSO ₅ a solid oxidant is administered. Other conditions are the same as in Example 1.

  The solution contained in the inner cylinder container was filtered under reduced pressure and separated into a solid and a liquid (hereinafter, referred to as “separated liquid”).

  In addition, when the noble metal density | concentration in a isolation | separation liquid was measured using the ICP-AES method, the correct value was not obtained. For this reason, the dissolution rate of the noble metal was calculated based on the weight change of the platinum powder before and after the introduction. As a result of X-ray diffraction analysis, it is confirmed that platinum contained in the residue is in a metal state.

  As a result, in Example 8, the dissolution rate of the noble metal was 61.1%.

(Example 9)
The dissolution rate of noble metal (platinum) was measured in the same manner as in Example 8. However, in Example 9, the platinum powder and the solid oxidizing agent were mixed well in advance in an agate mortar and then charged as a mixture into the inner tube container. The other conditions are the same as in Example 8.

  In addition, when the noble metal density | concentration in a isolation | separation liquid was measured using the ICP-AES method, the correct value was not obtained. For this reason, the dissolution rate of the noble metal was calculated based on the weight change of the platinum powder before and after the dissolution treatment.

However, as a result of X-ray diffraction analysis, it was confirmed that platinum contained in the residue was present in the form of potassium hexachloroplatinate (IV) (K ₂ PtCl ₆ ) in addition to the metal state. Therefore, the abundance ratio of the crystal phase was calculated from the peak intensity ratio of platinum (metal) and K ₂ PtCl _{6 as} a result of X-ray diffraction. Moreover, based on this abundance ratio, the weight change of the platinum powder before and after the dissolution treatment was calculated, and the dissolution rate of the precious metal was calculated.

  As a result, in Example 9, the dissolution rate of the noble metal was 93.0%.

From the comparison of the dissolution rates of platinum in Example 8 and Example 9, when KHSO ₅ is used as the solid oxidant, a larger dissolution rate can be obtained by mixing the noble metal-containing material and the solid oxidant in advance. I understood it.

From this, it is understood that KHSO ₅ has both the function of "directly oxidizing" platinum and the function of "indirectly oxidizing" platinum. That is, KHSO ₅ can oxidize a noble metal to some extent by mixing a noble metal-containing material and a solid oxidizing agent in advance, and then obtain a larger dissolution rate when the mixture is brought into contact with an acid solution. It can be said that you can.

(Example 10)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in Example 10, the amount of CeO _{2 to be} administered was 0.1 g. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 10, the dissolution rate of the noble metal was 68.9%.

(Example 11)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 11, the amount of CeO _{2 to be} administered was 0.25 g. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 11, the dissolution rate of the noble metal was 91.2%.

(Example 12)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 10, the amount of CeO _{2 to be} administered was 0.5 g. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 12, the dissolution rate of the noble metal was 97.6%.

(Example 13)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 13, 6 M hydrochloric acid was used as an acid solution. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 13, the dissolution rate of the noble metal was 98.9%.

(Example 14)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this Example 14, 3 M hydrochloric acid was used as an acid solution. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 14, the dissolution rate of the noble metal was 82.9%.

(Example 15)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 15, 1 M hydrochloric acid was used as an acid solution. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 15, the dissolution rate of the noble metal was 21.4%.

(Example 21)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 21, no solid oxidizing agent was used. That is, only platinum powder and hydrochloric acid were charged into the inner cylinder container. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 21, the dissolution rate of the noble metal was 3.8%.

(Example 22)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 22, no solid oxidizing agent was used. The processing time was 1 hour. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 22, the dissolution rate of the noble metal was 3.1%.

(Example 23)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 23, no solid oxidant was used. The processing time was 0.5 hours. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 23, the dissolution rate of the noble metal was 0.9%.

(Example 24)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 4. However, in this example 24, no solid oxidizing agent was used. The amount of 12M hydrochloric acid was 20 mL, and the treatment temperature and treatment time were 80 ° C. and 6 hours, respectively. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 24, platinum could not be detected in the separation solution.

(Example 25)
The dissolution rate of the noble metal (platinum) was measured in the same manner as in Example 1. However, in this example 25, no solid oxidizing agent was used. The amount of 12M hydrochloric acid was 20 mL, and the treatment temperature and treatment time were 80 ° C. and 6 hours, respectively. Other conditions are the same as in Example 1.

  Thereafter, the dissolution rate of the noble metal was calculated in the same manner as in Example 2. As a result, in Example 25, the dissolution rate of the noble metal was 1.5%.

  Table 1 below collectively shows the processing conditions and precious metal dissolution rates in Examples 1 to 21.

図４には、例１〜例５、および例２１〜例２５において得られた貴金属溶解率をまとめて示す。また、図５には、例６〜例１５において得られた貴金属溶解率をまとめて示す。

FIG. 4 collectively shows the precious metal dissolution rates obtained in Examples 1 to 5 and Examples 21 to 25. Moreover, in FIG. 5, the precious metal dissolution rate obtained in Examples 6 to 15 is shown collectively.

  From these results, it was confirmed that in Examples 1 to 15, the dissolution rate of platinum was significantly improved as compared with Examples 21 to 25.

(Example 31)
In the same manner as in Example 1, the dissolution rate of the noble metal was measured. However, in this example 31, 25 mg of palladium (Pd) powder was used as a noble metal. That is, 25 mg of palladium powder and 1.0 g of CeO ₂ were put into an inner cylinder container together with hydrochloric acid. Other conditions are the same as in Example 1.

  The dissolution rate of the noble metal (palladium) was calculated in the same manner as in Example 2.

  As a result, in Example 31, the dissolution rate of the noble metal (palladium) was 93.8%.

(Example 32)
In the same manner as in Example 1, the dissolution rate of the noble metal was measured. However, in this example 32, 25 mg of rhodium (Rh) powder was used as the noble metal. That is, 25 mg of rhodium powder and 1.0 g of CeO ₂ were put into an inner cylinder container together with hydrochloric acid. Other conditions are the same as in Example 1.

  The solution contained in the inner cylinder container was filtered under reduced pressure to separate the solid and the liquid.

  As a result, in Example 32, no solid (residue) was observed. That is, the charged rhodium was completely dissolved.

  Therefore, in Example 32, the dissolution rate of the noble metal (rhodium) was 100%.

(Example 33)
In the same manner as in Example 1, the dissolution rate of the noble metal was measured. However, in this example 33, 25 mg of ruthenium (Ru) powder was used as the noble metal. That is, 25 mg of ruthenium powder and 1.0 g of CeO ₂ were put into an inner cylinder container together with hydrochloric acid. Other conditions are the same as in Example 1.

  The dissolution rate of noble metal (ruthenium) was calculated in the same manner as in Example 2.

  As a result, in Example 33, the dissolution rate of the noble metal (ruthenium) was 27.4%.

(Example 34)
In the same manner as in Example 1, the dissolution rate of the noble metal was measured. However, in this example 34, 25 mg of Pt-Ir alloy wire was used as the noble metal. The ratio of platinum to iridium contained in the alloy wire is Pt: Ir = 80: 20 (% by mass).

  In the same manner as in Example 2, the dissolution rate of the noble metal was calculated.

  As a result, in Example 34, the dissolution rate of platinum was 43.3%, and the dissolution rate of iridium was 38.3%.

(Example 35)
In the same manner as in Example 1, the dissolution rate of the noble metal was measured. However, in this example 35, a mixed powder of 25 mg of Pt and Ir was used as the noble metal. The amount of platinum contained in the mixed powder was 20 mg, and the amount of iridium was 5 mg.

  In the same manner as in Example 2, the dissolution rate of the noble metal was calculated.

  As a result, in Example 35, the dissolution rate of platinum was 89.0%, and the dissolution rate of iridium was 36.6%.

(Example 41)
The dissolution rate of the noble metal was measured in the same manner as in Example 31. However, in Example 41, no solid oxidant was used. That is, only 25 mg of palladium powder and hydrochloric acid were charged into the inner cylinder container. Other conditions are the same as in Example 31.

  The dissolution rate of the noble metal (palladium) was calculated in the same manner as in Example 2.

  As a result, in Example 41, the dissolution rate of noble metal (palladium) was 4.0%.

(Example 42)
The dissolution rate of the noble metal was measured in the same manner as in Example 32. However, in this example 42, a solid oxidizing agent was not used. That is, only 25 mg of rhodium powder and hydrochloric acid were charged into the inner cylinder container. Other conditions are the same as in Example 32.

  The dissolution rate of the noble metal (rhodium) was calculated in the same manner as in Example 2.

  As a result, in Example 42, the dissolution rate of the noble metal (rhodium) was 4.6%.

(Example 43)
The dissolution rate of the noble metal was measured in the same manner as in Example 33. However, in this example 43, no solid oxidizing agent was used. That is, only 25 mg of ruthenium powder and hydrochloric acid were charged into the inner cylinder container. Other conditions are the same as in Example 33.

  The dissolution rate of noble metal (ruthenium) was calculated in the same manner as in Example 2.

  As a result, in Example 43, the dissolution rate of the noble metal (ruthenium) was 0.3%.

(Example 44)
The dissolution rate of the noble metal was measured in the same manner as in Example 34. However, in this Example 44, no solid oxidant was used. That is, only 25 mg of Pt-Ir alloy wire and hydrochloric acid were charged into the inner cylinder container. Other conditions are the same as in the case of Example 34.

  In the same manner as in Example 2, the dissolution rate of the noble metal was calculated.

  As a result, in Example 44, platinum and iridium were not detected in the separated liquid.

(Example 45)
The dissolution rate of the noble metal was measured in the same manner as in Example 35. However, in Example 45, no solid oxidant was used. That is, only the mixed powder (25 mg) of Pt powder and Ir powder and hydrochloric acid were put into the inner cylinder container. The other conditions are the same as in Example 35.

  In the same manner as in Example 2, the dissolution rate of the noble metal was calculated.

  As a result, in Example 45, the dissolution rate of platinum was 6.5%. On the other hand, iridium was not detected in the separated liquid.

  Table 2 below collectively shows the treatment conditions and the dissolution rates of the noble metals in Examples 31 to 35, and Examples 41 to 45.

図６には、例３１〜例３３、および例４１〜例４３において得られた貴金属溶解率をまとめて示す。また、図７には、例３４〜例３５、および例４４〜例４５において得られた貴金属溶解率をまとめて示す。

FIG. 6 collectively shows the precious metal dissolution rates obtained in Examples 31 to 33 and Examples 41 to 43. Moreover, in FIG. 7, the noble metal dissolution rate obtained in Example 34-Example 35 and Example 44-Example 45 is shown collectively.

  From these results, it was confirmed that in Examples 31 to 35, the dissolution rate of the noble metal was significantly improved as compared with Examples 41 to 45.

  The present invention is expected to be applied to the field of recycling for recovering precious metal components from precious metals contained in waste materials and the like.

Claims (13)

A method for recovering precious metals,
(I) preparing a noble metal-containing material, a solid oxidizing agent, and an acid solution;
(II) introducing the noble metal-containing material and the solid oxidizing agent into the acid solution, and reacting the noble metal-containing material at a temperature of 80 ° C. or higher;
Having a method.   The method according to claim 1, wherein in the step (II), the noble metal-containing material and the solid oxidizing agent are introduced in this order.   The method according to claim 1, wherein in the step (II), the noble metal-containing material and the solid oxidizing agent are introduced substantially simultaneously.   The method according to claim 3, wherein in the step (II), the noble metal-containing material and the solid oxidizing agent are mixed in advance and then introduced into the acid solution.   The method according to claim 1, wherein the step of reacting the noble metal-containing material at a temperature of 80 ° C. or more is performed in a closed container. A method for recovering precious metals,
(III) preparing a noble metal-containing material, a solid oxidizing agent, and an acid solution;
(IV) adding the acid solution and the solid oxidizing agent to the noble metal-containing material, and reacting the noble metal-containing material at a temperature of 80 ° C. or higher;
Having a method.   The method according to claim 6, wherein in the step (IV), the solid oxidizing agent is added to the noble metal-containing material before adding the acid solution.   The method according to claim 6, wherein in the step (IV), the solid oxidizing agent is premixed with the noble metal-containing material.   The method according to claim 6, wherein in the step (IV), the solid oxidizing agent is added to the acid solution after the acid solution is added.   The method according to any one of claims 6 to 9, wherein the step of reacting the noble metal-containing material at a temperature of 80 ° C or higher is performed in an airtight container.   The method according to any one of claims 1 to 10, wherein the noble metal comprises at least one selected from the group consisting of platinum, palladium, rhodium, iridium and ruthenium.   The solid oxidizing agent according to any one of claims 1 to 11, wherein the solid oxidizing agent contains at least one selected from the group consisting of a cerium (IV) compound, a manganese (IV) compound, a vanadium (V) compound, and a persulfate. The method described in one.   The method according to any one of claims 1 to 12, wherein the acid solution comprises at least one selected from the group consisting of hydrochloric acid, nitric acid, hydrofluoric acid, phosphoric acid, formic acid, and acetic acid.

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