JP2014055331A - Method for separating/recovering platinum group element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safe and simple method with a light environmental load for separating/recovering a platinum group element that is a recovery process of platinum group metals using a wet method and an ion exchange method and has an excellent rate of separation/recovery of each platinum group element.SOLUTION: A method for separating/recovering a platinum group element includes a leaching step for leaching a mixture of platinum group elements into a hydrochloric acid solution to prepare a leachate, a first separation/recovery step for separating/recovering palladium by bringing a palladium adsorbent into contact with the leachate, a second separation/recovery step for separating/recovering platinum by bringing a platinum adsorbent into contact with a leachate after the first separation/recovery obtained in the first separation/recovery step at a high velocity, the velocity at which rhodium being hardly adsorbed, and a third separation/recovery step for batchwise separating/recovering rhodium by bringing a rhodium adsorbent into contact with a leachate after the second separation/recovery obtained in the second separation/recovery step. The palladium adsorbent includes a porous resin and an extraction agent supported by the porous resin, while the platinum adsorbent and rhodium adsorbent are each a weak base ion exchange resin.

Description

  The present invention relates to a platinum group separation and recovery method for separating and recovering individual platinum group elements, particularly palladium, platinum, and rhodium, from a platinum group mixture obtained from an automobile waste catalyst or the like.

The platinum group is a generic name for six metals of platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), and osmium (Os). In the periodic table, elements located in the 5th and 6th periods and groups 8 to 10 have similar physical and chemical properties, high melting point, excellent heat resistance and corrosion resistance, and unique catalytic properties have.
The use of platinum, which was once familiar with daily necessities, such as heat-generating materials and fountain pen nibs, is now increasingly used as a catalyst for automobile catalysts, electronic parts, and chemical industries. Among them, most of the platinum group (50% palladium, 55% platinum, 87% rhodium) is used for automobile catalysts. This is because the catalytic activity is higher and the durability is better than other catalyst materials. In addition, as for automobile catalysts, no catalyst having a performance superior to that including a platinum group has been developed at present. Currently, demand for the platinum group in automobile catalysts is increasing due to stricter exhaust gas regulations.

  However, the platinum group is a rare element and has limited production, and the mine that is the primary source is biased to specific regions in a very limited country. Due to cost and environmental burden, it is a very expensive metal. Against this background, it is necessary to develop an efficient process for separating and recovering palladium, platinum, and rhodium from used products containing platinum group metals such as automobile waste catalysts, that is, urban mines (secondary resources). It is said that.

Conventionally, as a method for separating and recovering the platinum group, as a method for recovering and purifying rhodium, after adding hydrochloric acid to a rhodium hydrochloric acid solution to adjust the hydrochloric acid concentration to 1 to 6 N, divalent tin chloride is added and dialkyl sulfide is added. Discloses a method of adsorbing rhodium by contacting with a porous resin containing. (Patent Document 1)
Further, (Patent Document 2) states that “in the method of recovering a platinum group element from a chloride solution containing a platinum group element and an impurity element, the platinum group element is selected by contacting the chloride solution with a polyamine type anion exchange resin. A platinum group element characterized by comprising a first step of mechanically adsorbing, a second step of washing the resin after the adsorption treatment, and a third step of eluting the platinum group element from the resin after the washing treatment Is disclosed.

Japanese Patent No. 2826158 JP 2004-131745 A

However, the above conventional techniques have the following problems.
(1) The technique disclosed in (Patent Document 1) requires addition of 10 to 50 times the molar ratio of tin chloride to rhodium, which has a slow adsorption rate, and the measurement of rhodium content in the leachate and hydrochloric acid In addition to the need to adjust the concentration and the amount of tin chloride added, there is a problem that rhodium cannot be sufficiently adsorbed when the rhodium in the leachate is at a low concentration.
(2) Although the technique disclosed in (Patent Document 2) can separate and recover the platinum group, the platinum group contained in the solution cannot be separated and recovered for each individual metal element, and the purity and recovery rate of each individual metal are also low. It had the problem of being low.

  The present invention solves the above-mentioned conventional problems, and relates to a platinum group separation and recovery method for separating and recovering individual platinum group elements, particularly palladium, platinum and rhodium, from a platinum group mixture obtained from an automobile waste catalyst or the like. Without the agent, rhodium, which was difficult to recover in a short time, can be recovered selectively and in a short time without adjustment of additives, etc. Low environmental impact, excellent recovery efficiency for low-concentration metals such as palladium, platinum, and rhodium. Furthermore, the ion exchange method is used in each separation and recovery process, making operation easy and efficient. An object of the present invention is to provide a platinum group separation and recovery method that can be recovered, is excellent in workability, is safe and simple, and is low in cost and excellent in productivity.

In order to achieve this object, the platinum group separation and recovery method of the present invention has the following configuration.
The platinum group separation and recovery method according to claim 1,
(A) a leaching step of leaching a platinum group mixture composed of an automobile waste catalyst containing palladium, rhodium, platinum, etc. into a hydrochloric acid solution to prepare a leaching solution; and (b) a first leaching solution and a palladium adsorbent. A first separation / recovery step for separating and recovering the palladium by contacting in an adsorption separator; and (c) a first adsorption / recovery step packed in a second adsorption separator filled with a platinum adsorbent. A second separation and recovery step for separating and recovering the platinum by passing the leachate after separation and recovery at a high space velocity at which rhodium is not easily adsorbed; and (d) a second post-separation and recovery leachate after the second separation and recovery step; A rhodium adsorbent, and a third separation and recovery step for separating and recovering the rhodium in a batch manner by contacting the rhodium adsorbent in a stirred adsorption tank, and (e) the palladium adsorbent is a porous resin, Impregnated in the porous resin Comprising a polishes and, (f) the platinum adsorbent and the rhodium adsorbent has a structure which is weakly basic ion exchange resin.
With this configuration, the following effects can be obtained.
(1) Since it has a leaching process using a wet method in which a platinum group mixture comprising automobile waste catalyst or the like is directly leached with a hydrochloric acid solution, the environmental load is small, and palladium, rhodium, and platinum are selectively increased. Since it can extract to a hydrochloric acid solution with a content rate, palladium, rhodium, and platinum can be separated and recovered by providing each recovery step.
(2) Utilizing the difference in adsorption rate, platinum and rhodium can be recovered separately by using the column method for recovering platinum and the batch method for recovering rhodium. It can be performed stably.
(3) In the first separation and recovery step, the palladium adsorbent obtained by impregnating the porous resin with the extractant and the leachate are brought into contact with each other, so that only palladium or palladium can be selectively recovered without adsorbing platinum or rhodium.
(4) Although the weakly basic ion exchange resin can selectively adsorb platinum and rhodium, it is difficult for rhodium to adsorb the leachate after the first separation and recovery including platinum and rhodium in the second separation and recovery step. Since it is brought into contact with the platinum adsorbent (weakly basic ion exchange resin) at a high space velocity, rhodium having a low adsorption rate is difficult to adsorb and platinum can be selectively separated and recovered.
(5) In the third separation and recovery process, rhodium is separated and recovered by the batch method, so that the adsorption time required for one and a half months can be shortened from several hours to several tens of hours in the column method. In addition to being excellent, the separation and recovery rate is excellent even if the rhodium concentration in the leachate after the second separation and recovery is low.

Here, the platinum group mixture used in the leaching step is particularly limited as long as it contains a platinum group such as a catalyst for mufflers of automobiles and motorcycles, a catalyst for exhaust gas from ships and boilers, and a fuel cell catalyst. The shape of the waste catalyst may be any shape such as a mesh shape, a semi-spiral shape, or a pellet shape.
Further, the waste catalyst may be pulverized to a particle size of about 0.01 to 5 mm. When the waste catalyst is pulverized, it is easy to transport the waste catalyst, and it is possible to improve workability such as introduction of the waste catalyst and filtration in the leaching process.
As a method for pulverizing the waste catalyst, a method of pulverizing roughly with a hammer or the like and then pulverizing to an arbitrary particle size with a ball mill or a crusher is preferably selected.

As a method for adjusting the leachate, although depending on the temperature conditions, the waste catalyst was immersed in a 0.5 to 10 mol / L hydrochloric acid solution heated to 50 to 80 ° C. for 1 hour or more, and the metal in the waste catalyst was leached. For example, a method of filtering and separating is preferably used.
The adjustment time can be shortened by adjusting the leachate while stirring the hydrochloric acid solution. However, when the adjustment amount of the leachate is small, it is less time-consuming to leave it without stirring and the convenience can be improved.
In the preparation of the leachate, the weight mixing ratio of the hydrochloric acid solution (c) and the waste catalyst (d) depends on the concentration of the hydrochloric acid solution and the like, but preferably c / d ≧ 10, preferably c / d ≧ 20. . As the weight ratio becomes smaller than 20, the leaching rate of noble metals tends to deteriorate although it depends on the concentration and temperature of the hydrochloric acid solution.

As the leachate, a mixed acid of perchloric acid-hydrochloric acid or nitric acid-hydrochloric acid (including aqua regia) can be used in addition to a hydrochloric acid solution. Among these, hydrochloric acid solution is preferable because it does not oxidize the adsorbent in each separation and recovery step and hardly deteriorates.
Further, it is preferable to add sodium perchlorate or the like to the hydrochloric acid solution because an effect such as shortening the leaching time of the platinum group from the spent catalyst can be obtained.
The concentration of the hydrochloric acid solution used in the leaching step is suitably selected from 0.5 mol / L to 10 mol / L, preferably from 1 mol / L to 5 mol / L, depending on the temperature conditions. As it becomes lower than 1 mol / L, the extraction of the platinum group from the spent catalyst becomes insufficient, and the leaching efficiency tends to decrease. Further, as it becomes higher than 5 mol / L, the selectivity of palladium of the palladium adsorbent in the first separation / recovery process tends to be low, and when it exceeds 10 mol / L, this tendency becomes remarkable, which is not preferable.

In the palladium adsorbent of the first separation and recovery step, the extractant may be a general formula R ₁ such as di-n-hexyl sulfide (hereinafter referred to as DHS) having sulfur as a functional group or di-n-octyl sulfide. —S—R ₂ (wherein R ₁ and R ₂ are an alkyl group having 5 to 10 carbon atoms, an allyl group, an aryl group, etc., and R ₁ and R ₂ are not simultaneously hydrogen). Or the like can be used.
The porous resin is not particularly limited as long as it has high hydrophobicity and can support the extractant by hydrophobic interaction. Ester-based synthetic adsorbent, styrene-divinylbenzene copolymer adsorbent, etc. Can be used. The porous resin has a specific surface area of 500 to 2000, preferably 500 to 1200 m ² / dry-g. In the adsorption / elution reaction of the resin, the diffusion into the resin is controlled, so that the better the resin is, the easier the elution rate is and the easier it is to separate.
Since the amount of palladium adsorbed tends to decrease as the amount of extractant impregnated into the porous resin decreases, the porous resin is preferably impregnated with the maximum amount of extractant that can be impregnated. . For example, in the case of DHS, 1.4 mmol / g-resin is preferable.

The first adsorption / separator in the first separation / recovery step is not limited as long as the palladium adsorbent and the leachate can be accommodated and brought into contact with each other. In order to prevent leakage of the extractant from the palladium adsorbent, a fixed bed is used. The method is preferred.
Also, palladium adsorption methods include column methods and batch methods, but it is preferable to use the column method. This is because, in the case of the batch method, the palladium adsorbent and the leachate are brought into fluid contact, so that the extractant impregnated in the porous resin is liable to leak and is not preferable.

  In the second separation and recovery step, the platinum adsorbent is preferably a weakly basic anion exchange resin, but a strong basic anion exchange resin can also be used. When the functional groups of these weakly basic anion exchange resins and strong basic anion exchange resins are neutralized, it is preferable because the adsorption property of platinum is improved by substituting the amino group counter ion with a hydroxyl group.

In the second separation / recovery step, as a platinum adsorption method, it is sufficient that the leachate can be passed after the first separation / recovery at a high space velocity at which rhodium is hardly adsorbed, and a column method can be used. This is preferable because the contact time between the first separated and recovered leachate and the platinum adsorbent can be easily adjusted only by adjusting the space velocity and it is easy to prevent the adsorption of rhodium.
As the second adsorptive separator in the second separation and recovery step, a fixed bed system, a moving bed system, a fluidized bed system, or the like can be used.

  In the third separation and recovery step, the rhodium adsorbent is preferably a weakly basic anion exchange resin. Further, when the functional group of the weakly basic anion exchange resin is neutralized, it is preferable because the adsorption property of platinum is improved by replacing the counter ion of the amino group with a hydroxyl group.

In the third separation and recovery step, a batch method is preferably used as the rhodium adsorption method. The batch method has a lower efficiency than the column method, but rhodium has a slower adsorption rate to the rhodium adsorbent, and the rhodium adsorption takes one and a half months in the column method. It is preferable because the leachate can be easily contacted and rhodium can be adsorbed in several hours to several tens of hours depending on other conditions. Further, when precipitation occurs during the separation and recovery of rhodium, the batch method is advantageous because there is no clogging of the column.
The stirring type adsorption tank in the third separation / recovery step may be anything as long as it can be performed by a batch method, and a stirring tank, a shaker, or the like is used.
Further, it is preferable to provide a concentration step for concentrating the exudate after the second separation / recovery by heating or the like before the third separation / recovery step, so that rhodium is easily adsorbed by the rhodium adsorbent and the recovery rate can be increased. .

  In the first separation / recovery step, the second separation / recovery step, and the third separation / recovery step, the reaction temperature is not particularly limited, and can be performed at room temperature. In addition, there is no need for equipment such as a temperature controller, a heater, or a heat insulating material, and it is excellent in resource saving, and the entire apparatus can be made compact, so that it is excellent in space saving.

  Since the metal in the waste liquid after the third separation and recovery step can be recovered by precipitation separation, metals other than the platinum group, rare earths, and the like can also be reused.

The invention according to claim 2 of the present invention is the platinum group separation and recovery method according to claim 1, wherein the extractant is represented by the general formula R ₁ -SR ₂ (wherein R ₁ and R ₂ Is an alkyl group having 5 to 10 carbon atoms, an allyl group, an aryl group or the like, and R ₁ and R ₂ do not simultaneously become hydrogen).
With this configuration, in addition to the operation obtained in the first aspect, the following operation can be obtained.
(1) Since the extractant is a compound represented by the general formula R ₁ —S—R ₂ , palladium can be more selectively adsorbed in the first separation and recovery step, and the separation and recovery efficiency of palladium is increased. Can do.

Here, as the extractant, the general formula R ₁ —S—R ₂ (wherein R ₁ and R ₂ are an alkyl group having 5 to 10 carbon atoms, an allyl group, an aryl group, etc., and R ₁ and R 2) ₂ is not hydrogen at the same time. Among them, di-n-hexyl sulfide (hereinafter referred to as DHS) is preferable because it is easily available and excellent in productivity.

The invention according to claim 3 of the present invention is the platinum group separation and recovery method according to claim 1 or 2, wherein the porous resin is an ester-based synthetic adsorbent.
With this configuration, in addition to the operation obtained in the first or second aspect, the following operation can be obtained.
(1) Since an ester-based synthetic adsorbent excellent in porosity is used as the porous resin, the elution rate is high and palladium can be more easily separated.
(2) Since the porous resin is an ester-based synthetic adsorbent, the hydrophobic resin is highly hydrophobic, and the extractant can be supported by hydrophobic interaction, and an extractant such as DHS can be applied to the ion exchange method. it can.

The invention according to claim 4 of the present invention is the platinum group separation and recovery method according to any one of claims 1 to 3, wherein the palladium adsorbent is not subjected to a hydrophilic treatment. ing.
According to this configuration, in addition to the action obtained in any one of claims 1 to 3, the following action is obtained.
(1) Since the palladium adsorbent is not subjected to hydrophilic treatment, leakage of DHS due to continuous use or the like can be suppressed in the first separation and recovery step, and a decrease in the adsorption rate of palladium can be suppressed.

  Here, the palladium adsorbent is preferably not subjected to hydrophilic treatment. When the palladium adsorbent is subjected to hydrophilic treatment with ion-exchanged water, sodium dodecyl sulfate solution, etc., the extractant impregnated in the porous resin is caused by the extraction agent such as DHS and sodium dodecyl sulfate forming micelles. It is because it becomes easy to leak.

The invention according to claim 5 of the present invention is the platinum group separation and recovery method according to any one of claims 1 to 4, wherein the second separation and recovery step is a column method. The space velocity of the leachate after separation / recovery is 2 to 10 h ⁻¹ .
With this configuration, in addition to the action obtained in any one of claims 1 to 4, the following action is obtained.
(1) Since the second separation and recovery step is a column type and the space velocity of the leachate after the first separation and recovery is 2 to 10 h ⁻¹ , rhodium having a slow adsorption rate in the second separation and recovery step Is hardly adsorbed and platinum is excellent in selectivity.

Here, the space velocity is the flow rate of the liquid flowing in the column divided by the volume inside the column.
In the second separation and recovery step, the space velocity is preferably 2 to 10 h ⁻¹ . As the space velocity becomes smaller than 2 h ⁻¹ , the amount of rhodium adsorbed on the platinum adsorbent increases, and the selectivity of platinum in the second separation and recovery step tends to decrease. Further, as it becomes larger than 10, platinum tends to be unable to be adsorbed to the platinum adsorbent, which is not preferable.

A sixth aspect of the present invention is the platinum group separation and recovery method according to any one of the first to fifth aspects, wherein the rhodium adsorbent amount and the third amount in the third separation and recovery step are the same. The solid-liquid ratio of the amount of leachate after 2 separation and recovery is 1.5 to 5 g / L.
With this configuration, in addition to the action obtained in any one of claims 1 to 5, the following action is obtained.
(1) Since the rhodium adsorbent in the third separation / recovery step and the leaching liquid after the second separation / recovery are configured to be 1.5 to 5 g / L, the rhodium concentration is increased from the leachate after the second separation / recovery step. Even at low concentrations, the rhodium absorption rate can be increased.

  As the solid-liquid ratio between the rhodium adsorbent amount in the third separation and recovery step and the amount of leachate after the second separation and recovery in the batch, 1.5 to 5 g / L, preferably 3 to 5 g / L is suitably used. When the solid-liquid ratio is smaller than 3 g / L, the amount of the leachate after the second separation and recovery with respect to the rhodium adsorbent is not sufficient, and the adsorption rate of rhodium tends to decrease. Since a tendency becomes remarkable, it is not preferable. Moreover, as the solid-liquid ratio becomes larger than 5 g / L, the amount of the leachate after the second separation and recovery becomes smaller than that of the adsorbent, so that the amount of rhodium adsorbed on the adsorbent decreases, and rhodium is eluted. This is not preferable because the amount of the eluent to be used needs to be reduced and the productivity is deteriorated.

As described above, according to the platinum group separation and recovery method of the present invention, the following advantageous effects can be obtained.
According to the invention of claim 1,
(1) A platinum group separation and recovery method capable of separating and recovering palladium, rhodium and platinum separately at a high content can be provided.

According to the second aspect of the present invention, in addition to the effect of the first aspect, (1) a platinum group separation and recovery method having an excellent palladium separation and recovery rate can be provided.

According to the invention described in claim 3, in addition to the effect of claim 1 or 2, (1) it is possible to provide a platinum group separation and recovery method which is excellent in operability and excellent in palladium separation and recovery.

According to the invention of claim 4, in addition to the effect of any one of claims 1 to 3, (1) leakage of the extractant in the palladium adsorbent can be suppressed, and the adsorption rate of palladium is reduced. It is possible to provide a method for separating and recovering platinum group which is difficult to cause.

According to the invention of claim 5, in addition to the effect of any one of claims 1 to 4, (1) platinum capable of selectively adsorbing platinum is difficult to adsorb rhodium having a low adsorption rate. A method for separating and recovering tribes can be provided.

According to the sixth aspect of the present invention, in addition to the effect of any one of the first to fifth aspects, (1) a platinum group separation and recovery method capable of increasing the adsorption rate of rhodium can be provided. .

Flowchart of Platinum Group Separation and Recovery Method of Embodiment 1 The figure which shows the adsorptivity to the palladium adsorbent of the metal in the leachate of each hydrochloric acid concentration Figure showing changes in hydrophilic treatment and metal adsorption Breakthrough curve of platinum and rhodium in Example 3 Elution curve of eluent of Example 3 Diagram showing the effect of shaking time on rhodium adsorption The figure which shows the breakthrough curve of the comparative example 1 Relationship diagram between rhodium adsorption rate and solid-liquid ratio Relationship between pH and precipitation rate in Example 5 Relationship between pH and precipitation rate in Example 6 Relationship between pH and precipitation rate in Example 7

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a flowchart showing a platinum group separation and recovery method in the first embodiment.
In FIG. 1, S1 is a leachate adjustment step in which a waste catalyst is immersed in a 0.5 to 10 mol / L hydrochloric acid solution having a liquid temperature of 50 to 80 ° C. to obtain a leachate from which palladium, rhodium and platinum have been leached, and S2 is extracted into a porous resin. Pd adsorbent adjustment step for impregnating the adsorbent to obtain a palladium adsorbent, S3 is obtained in the leachate adjustment step S1 in the first adsorption separator such as a column packed with the palladium adsorbent obtained in the palladium adsorbent adjustment step S2. A first separation and recovery step of recovering the palladium eluent by eluting palladium from the palladium adsorbent with an eluent such as an ammonia solution after supplying the leachate and selectively adsorbing palladium on the palladium adsorbent; A palladium simple substance is obtained by separating and recovering a precipitate containing palladium from the palladium eluent obtained in the first separation and recovery step S3 and performing reduction firing. Radiation precipitation firing step, S5 is a platinum adsorbent adjustment step of substituting a counter ion of an amino group, which is a functional group of a weakly basic anion exchange resin as a platinum adsorbent, with a hydroxyl group, and S5 is a platinum adsorbent adjustment step S5. The first separated and recovered leachate from which palladium has been separated in the first separation and recovery step S3 is supplied at a space velocity of 2 to 10 h ^{−1 to} a second adsorption separator such as a column packed with the obtained platinum adsorbent. A second separation and recovery step of recovering the platinum eluent by eluting platinum from the platinum adsorbent with an eluent such as a thiourea-hydrochloric acid solution after platinum is selectively adsorbed on the platinum adsorbent, and S7 is the second separation. A platinum precipitation firing step for separating and recovering platinum-containing precipitates from the platinum eluent obtained in the recovery step S6 and reducing and firing them to obtain a simple substance of platinum. S8 is a weakly basic anion exchange resin which is a rhodium adsorbent. Functional group A rhodium adsorbent adjustment step of substituting a counter ion of an amino group with a hydroxyl group, S9 after the second separation and recovery in which the rhodium adsorbent obtained in the rhodium adsorbent adjustment step S8 and platinum in the second separation step S6 are separated The leachate is mixed in a stirred adsorption tank so that the solid-liquid ratio is 1.5 to 5 g / L and stirred to selectively adsorb rhodium, followed by rhodium adsorption with an eluent such as sodium chlorate-hydrochloric acid solution. The third separation and recovery step of eluting rhodium from the agent and recovering the rhodium eluent, S10 separates and recovers the rhodium-containing precipitate from the rhodium eluent obtained in the third separation and recovery step, followed by reduction firing. This is a rhodium precipitation firing step for obtaining a simple substance.

In the leachate adjustment step S1, the waste catalyst may be directly immersed in a hydrochloric acid solution, but a catalyst crushed to a size of about 0.01 to 5 mm may be used.
As a method for crushing the waste catalyst, a ball mill, a crusher, or the like can be used.

The concentration of the hydrochloric acid solution is preferably 0.5 to 10 mol / L depending on conditions such as temperature.
Regarding the waste catalyst and the hydrochloric acid solution, the weight ratio of the waste catalyst amount c and the hydrochloric acid solution amount d is preferably c / d ≧ 10, preferably c / d ≧ 20.
In addition to the hydrochloric acid solution, a perchloric acid-hydrochloric acid, a mixed acid of nitric acid-hydrochloric acid, or the like can also be used for the leachate. Further, by adding sodium perchlorate or the like to the hydrochloric acid solution, the effect of shortening the extraction time of the platinum group from the spent catalyst and improving the adsorption rate of the platinum group in each separation and recovery step can be obtained.

In the palladium adsorbent adjustment step S2, the extractant is represented by the general formula R ₁ —S—R ₂ (wherein R ₁ and R ₂ are an alkyl group, an allyl group or an aryl group having 5 to 10 carbon atoms, R DHS and di-n-octyl sulfide which are extractants represented by ₁ and R ₂ are not simultaneously hydrogen) can be used.
In addition, as the porous resin, an ester-based synthetic adsorbent, a styrene-divinylbenzene copolymer adsorbent, or the like can be used.
As an eluent for eluting palladium from a palladium adsorbent, a 0.5 to 5 mol / L ammonia solution is preferably used, but a thiourea-hydrochloric acid solution or the like can also be used. Further, the concentration of the eluent may be appropriately changed depending on elution conditions and the like.

  The first adsorption / separator used in the first separation / recovery step S3 only needs to be able to contain and contact the palladium adsorbent and the leachate, but to prevent leakage of the extractant from the palladium adsorbent to a minimum. The fixed layer method is preferred.

  In the palladium precipitation baking step S4, any method may be used for recovering palladium as long as palladium can be recovered from the palladium eluent, such as a method in which the palladium eluent is adjusted to around pH 1 and the resulting precipitate is reduced and fired. It is done.

  In the platinum adsorbent adjusting step S5, a weak basic anion exchange resin, a strong basic anion exchange resin, or the like can be used as the platinum adsorbent.

In the second separation / recovery step S6, the column method is preferably used for the adsorption of platinum, and the space velocity of the first separated and recovered leachate in the column is preferably 2 to 10 h ⁻¹ .
As the second adsorptive separator in the second separation / recovery step S6, the column method can be suitably used as long as the leachate after the first separation / recovery can be passed so that the space velocity becomes 2 to 10 h ⁻¹ . The column method is preferable because the contact time between the leachate after the first separation and recovery and the platinum adsorbent can be easily adjusted only by adjusting the space velocity and it is easy to prevent the adsorption of rhodium.
As an eluent for eluting platinum from a platinum adsorbent, it is preferable to use a 0.01-1 mol / L thiourea-0.1-5 mol / L hydrochloric acid solution. Further, the concentration of the eluent may be appropriately changed depending on elution conditions and the like.

  In the platinum precipitation baking step S7, any platinum recovery method can be used as long as platinum can be recovered from the platinum eluent, and a method of adjusting the platinum eluent to around pH 10 and reducing and baking the obtained precipitate is used. It is done.

  In the rhodium adsorbent adjustment step S8, a weakly basic anion exchange resin or the like can be used as the rhodium adsorbent.

In the third separation and recovery step S9, rhodium has a slow adsorption rate, and therefore, it is preferable to use a batch method for rhodium adsorption.
Any stirring type adsorption tank in the third separation and recovery step S9 can be used as long as it can perform separation and recovery of rhodium such as a stirring tank and a shaker by a batch method.
As an eluent for eluting rhodium from the rhodium adsorbent, a 0.1 to 2 mol / L sodium chlorate-1 to 5 mol / L hydrochloric acid solution is preferably used, but aqua regia and the like can also be used. The concentration of the eluent may be appropriately changed depending on elution conditions and the like.

  In the rhodium precipitation firing step 10, any method may be used for collecting rhodium as long as rhodium can be recovered from the rhodium eluent. The rhodium eluent is adjusted to around pH 10 and the resulting precipitate is reduced and fired. It is done.

  In the first separation / recovery step S3, the second separation / recovery step S6, and the third separation / recovery step S9, the reaction temperature may be room temperature.

The platinum group separation and recovery method will be described below.
In the leachate adjustment step S1, first, an automobile waste catalyst is immersed in a 0.5 to 10 mol / L hydrochloric acid solution heated to 50 to 80 ° C. for 24 hours to prepare a leachate.

In the palladium adsorbent adjustment step S2, a porous resin having a specific surface area of 500 to 1200 m ² / dry-g, DHS, and acetone are placed in an eggplant flask and vacuum dried at room temperature to obtain a palladium adsorbent.

Next, in the first separation and recovery step S3, first, the palladium adsorbent obtained in the palladium adsorbent adjusting step is packed into a column (first adsorption separator), and both ends are filled with glass wool. Next, preparation of the first separation and recovery step S3 is performed by allowing ion-exchanged water to pass through and washing and degassing. At this time, the palladium adsorbent is preferably packed in a close-packed manner in the column.
Next, the leachate obtained in the leachate adjustment step S1 is passed through to adsorb palladium, and after the adsorption reaches breakthrough, it is washed again with ion-exchanged water. Finally, a 1.5 mol / L ammonia solution is passed through. And the adsorbed palladium is eluted to obtain a palladium eluent.

  In the palladium precipitation firing step S4, first, a 1 mol / L hydrochloric acid solution is added to the eluent collected in the first separation and recovery step S3, adjusted to around pH = 1, and left overnight. Next, the eluate is subjected to centrifugation and the like, and separated into a precipitate and a supernatant. The obtained precipitate is washed with ion-exchanged water and dried to a constant weight at a temperature of 105 ° C. or higher in a vacuum dryer. Next, the precipitate is put into a quartz reducing tube and reduced and fired at about 300 to 400 ° C. for about 2 hours in a hydrogen atmosphere to obtain a simple palladium metal having a purity of 99.99% or more.

  Next, in the platinum adsorbent adjustment step S5, in order to substitute the counter group of the amino group, which is a functional group of the weak basic anion exchange resin, with a hydroxyl group, the weak basic anion exchange resin is added with 1 mol / L hydrochloric acid. A platinum adsorbent is prepared by washing the solution, ion-exchanged water, 1 mol / L sodium hydroxide solution, and ion-exchanged water multiple times in this order, followed by vacuum drying.

In the second separation and recovery step S6, the platinum adsorbent obtained in the platinum adsorbent adjustment step S5 is first packed in a column (second adsorption separator), and both ends thereof are filled with glass wool. Next, ion-exchanged water is passed through, washed and degassed to prepare for the second separation and recovery step S6.
Next, after the first separation and recovery step, the leachate is passed through at a space velocity of 2 to 10 h ⁻¹ to adsorb platinum to the platinum adsorbent, and after the adsorption reaches breakthrough, it is washed again with ion exchange water. Finally, a 0.1 mol / L thiourea-1.0 mol / L hydrochloric acid solution is passed as an eluent to obtain a platinum eluent from which the adsorbed metal has been eluted.

In the platinum precipitation baking step S7, first, in the eluent obtained in the second separation and recovery step S6, a precipitate in which thiourea is complexed with platinum is present. Divide into a precipitate and a supernatant of complexed urea and platinum.
Next, 1 moL / L sodium hydroxide solution is added to the supernatant to adjust to pH = 10, and the mixture is allowed to stand overnight. The supernatant is further separated by centrifugation, etc., and the precipitate is centrifuged. It wash | cleans with an ultrapure water using separation, and it is made to dry to a constant weight at the temperature of 105 degreeC or more with a vacuum dryer.
Next, the resulting precipitate, a precipitate in which thiourea and platinum were complexed were mixed, and reduced and calcined at 300 to 500 ° C. for 2 hours in a hydrogen atmosphere to obtain platinum alone having a purity of 99.99% or more. .

  In the rhodium adsorbent adjustment step S8, in order to replace the counter ion of the amino group, which is a functional group of the weakly basic anion exchange resin, with a hydroxyl group, the weakly basic anion exchange resin is added with a 1 mol / L hydrochloric acid solution, an ion A rhodium adsorbent is obtained by performing vacuum drying after washing a plurality of times in the order of exchange water, 1 mol / L sodium hydroxide solution, and ion exchange water. (S8)

In the third separation and recovery step S9, the rhodium adsorbent obtained in the rhodium adsorbent adjustment step S8 and the second separated and recovered leachate are mixed at a solid-liquid ratio of 1.5 to 5 g / L, and 60 to 60 using a stirring tank. The rhodium is adsorbed by shaking at 150 rpm for several hours to several tens of hours.
Next, the rhodium adsorbent after rhodium adsorption and 1.0 mol / L sodium chlorate-2.0 mol / L hydrochloric acid solution are put in a container, shaken for 48 hours to elute rhodium, shake and filter, A rhodium eluent is obtained.

In the rhodium precipitation firing step S10, first, the temperature of the rhodium eluent obtained in the third separation and recovery step S9 is increased to about 80 ° C., and a 2 mol / L sodium hydroxide solution is added to adjust pH = 10. A containing precipitate is produced. Next, the eluent that has precipitated is filtered, and the resulting precipitate is washed with ultrapure water using centrifugation or the like, and dried to a constant weight at a temperature of 105 ° C. or higher by vacuum drying.
Next, the obtained precipitate is reduced and calcined at about 500 ° C. for about 2 hours in a hydrogen atmosphere to obtain rhodium having a purity of 99.99% or more.

According to the platinum group separation and recovery method in the first embodiment as described above, the following effects are obtained.
(1) Since it has a leaching process using a wet method in which automobile waste catalyst is leached directly with hydrochloric acid solution, the environmental load is small, and palladium, rhodium and platinum are selectively converted into hydrochloric acid solution at high content. Since extraction can be performed, palladium, rhodium, and platinum can be selectively separated and recovered in each recovery step.
(2) In the first separation step S3, the palladium adsorbent impregnated with the extractant in the porous resin and the leachate are brought into contact with each other, so that only palladium or palladium can be selectively separated and recovered without adsorbing platinum or rhodium. .
(3) By increasing the space velocity in the second separation and recovery step S6, only platinum can be separated and recovered without adsorbing rhodium having a low adsorption rate on the platinum adsorbent.
(4) In the third separation and recovery step S9, rhodium is adsorbed on the rhodium adsorbent by the batch method, so that the adsorption time of one and a half months can be shortened from several hours to several tens of hours in the column method. In addition, the separation and recovery rate is excellent even if the rhodium concentration in the leachate after the second separation and recovery is low.
(6) In the first separation and recovery step S3, when the extractant is DHS, palladium can be adsorbed more selectively, so that the efficiency of separation and recovery of palladium can be increased.
(7) When an ester-based synthetic adsorbent excellent in porosity (large specific surface area) is used as the porous resin, the elution rate is high and palladium can be more easily separated.
(8) Since the hydrophilic treatment is not performed on the palladium adsorbent, leakage of DHS in continuous use or the like can be suppressed in the first separation and recovery step S3, and a decrease in the adsorption rate of palladium can be suppressed.
(9) Since the second separation and recovery step S6 is a column type, and the space velocity of the leachate after the first separation and recovery is 2 to 10 h ⁻¹ , rhodium having a low adsorption rate is difficult to be adsorbed, Platinum can be selectively adsorbed.
(10) Since the solid-liquid ratio between the rhodium adsorbent in the third separation / recovery step S9 and the second separation / recovery leachate is 1.5 to 5 g / L, the leachate after the second separation / recovery step. Therefore, even if the rhodium concentration is low, the absorption rate of rhodium can be increased.

Hereinafter, the present invention will be specifically described by way of examples. The present invention is not limited to these examples.
Example 1
<Change in selectivity of palladium adsorbent due to hydrochloric acid concentration in leachate>
20 mL of each metal hydrochloric acid solution prepared by dissolving 50 mg / L of palladium, rhodium, platinum, cerium, iron, magnesium, and aluminum in a 1,3,5,7,9 mol / L hydrochloric acid solution was prepared.
Next, 27.26 g of porous resin (manufactured by Mitsubishi Chemical Corporation: Diaion HP2MG) and 11.48 g of DHS (manufactured by Daihachi Kogyo Co., Ltd.) are placed in a eggplant flask in a 500 mL eggplant flask, and 200 mL of acetone is further added. In addition, drying was performed at 105 ° C. for 12 hours using a vacuum dryer (EYELA Tokyo Rika Co., Ltd .: VOS-201SD) to obtain a palladium adsorbent impregnated with 1.46 mmol / g of DHS.
20 mg of the prepared palladium adsorbent and 20 mL of the prepared hydrochloric acid solution are placed in a 50 mL Erlenmeyer flask and shaken with a shaker (EYELA Tokyo Rika Co., Ltd .: NTS-4000C) for 24 hours at 25 ° C. and 60 rpm. did. Thereafter, the hydrochloric acid solution was filtered to obtain a filtrate. The obtained filtrate was measured for each metal concentration using an induction plasma emission spectroscopic analyzer ICP-AES (manufactured by Shimadzu Corporation: ICP-7000). The results are shown in Table 1 and FIG.

FIG. 2 is a diagram showing the adsorptivity of the metal in the leachate having various hydrochloric acid concentrations to the palladium adsorbent.
As shown in FIG. 2, when the hydrochloric acid concentration is 1 to 5 mol / L, the palladium adsorbent made of DHS-impregnated porous resin shows high selectivity to palladium, and when it becomes 7 mol / L, it adsorbs other metals in minute amounts. I understand that. Furthermore, at 9 mol / L, it can be seen that the adsorption rate of iron and the like is close to 30%, and the selectivity is poor. Thus, when preparing a leaching solution with a 1-5 mol / L hydrochloric acid solution, it turned out that a palladium adsorbent has very high selectivity with respect to palladium. This is considered to be due to the fact that palladium, which is a soft acid, and sulfur, which is a soft base, form a stable complex according to the HSAB rule.

<Leakage of palladium adsorbent extractant>
(Example 2)
Example 1 was carried out in the same manner as in Example 1 except that 20 mL of a 1 mol / L hydrochloric acid solution containing 50, 100, 150, 200, and 250 mg / L of palladium was used instead of each metal hydrochloric acid solution.

(Comparative Example 1)
Into a 50 mL Erlenmeyer flask, 20 mL of the palladium adsorbent of Example 1 was charged with 20 mL of ion-exchanged water, and the palladium adsorbent was subjected to a hydrophilic treatment by shaking for 24 hours at 25 ° C. and 60 rpm. Except for this, the procedure was the same as in Example 2.

(Comparative Example 2)
Into a 50 mL Erlenmeyer flask, 20 mg of the palladium adsorbent of Example 1 was added 20 mL of a 10 wt% sodium dodecyl sulfate solution, and the mixture was shaken with a shaker for 24 hours at 25 ° C. and 60 rpm, so that the palladium adsorbent was hydrophilic. The procedure was the same as Example 2 except that the treatment was performed.
Table 2 and FIG. 3 show the metal adsorptivity of Example 2 and Comparative Examples 1 and 2, and Table 3 shows the leakage rate of the extractant (DHS).

FIG. 3 is a diagram showing changes in hydrophilic treatment and metal adsorption properties, and Table 3 is a table showing the difference in hydrophilic treatment and the amount of extractant (DHS) leakage. The leakage rate was calculated from the ratio of the palladium adsorption amount of Comparative Examples 1 and 2 to the palladium adsorption amount of the palladium adsorbent of Example 1.
From FIG. 3, the adsorption amount of palladium not subjected to hydrophilic treatment is about 0.75 mmol / g, while the adsorption amount of Comparative Example 1 subjected to hydrophilic treatment is about 0.35 mmol / g. The adsorption amount of Example 2 was about 0.6 mmol / g.
Further, from Table 1, compared with the palladium adsorbent of Example 1 that was not subjected to hydrophilic treatment, 20% was obtained in Comparative Example 1 in which the hydrophilic treatment of the palladium adsorbent was performed with ion-exchanged water, and palladium was adsorbed with a sodium dodecyl sulfate solution. In Comparative Example 2 in which the agent was subjected to hydrophilic treatment, 47% of DHS leaked out. This is considered due to the fact that DHS and sodium dodecyl sulfate form micelles.
From the above, it was shown that the palladium adsorbent should be used without being subjected to hydrophilic treatment.

(Example 3)
<Optimization of space velocity for separation and recovery of platinum>
110 g of weakly basic anion exchange resin (Mitsubishi Chemical Corporation: Diaion WA-21) was prepared, 300 mL of 1 mol / L hydrochloric acid solution (manufactured by Wako Pure Chemical Industries, Ltd.), ion-exchanged water 300
mL, 1 mol / L sodium hydroxide solution 300 mL (manufactured by Wako Pure Chemical Industries, Ltd.) and ion-exchanged water 300 mL were washed in this order, and after repeating this three times, a vacuum dryer (EYELA Tokyo Rika Equipment Co., Ltd .: VOS) -201SD) and dried at 105 ° C. for 12 hours to obtain a platinum adsorbent.
Next, as a hydrophilic treatment of WA-21, 0.1 wt% sodium dodecyl sulfate and a platinum adsorbent were added, and the mixture was shaken for 24 hours with a shaker (EYELA Tokyo Rika Co., Ltd .: NTS-4000C). After shaking, filtration was performed, and glass wool was packed at both ends of a hydrophilically treated platinum adsorbent (1.75 g) packed in a column having an inner diameter of 8 mm and a length of 100 mm. Next, after passing ion-exchanged water through washing and deaeration, a hydrochloric acid solution ([HCl] = 5 mol / L) having the composition shown in Table 4 is used until the space velocity of the metal adsorption reaches breakthrough. After passing under the condition of 5 h ^−1, the solution was washed again with ion exchange water, and finally 0.1 mol / L thiourea-1.0 mol / L hydrochloric acid solution and 1.0 mol / L sulfuric acid were passed as eluents. The adsorbed metal was eluted to obtain an eluent.
Peristaltic pump (EYELA Tokyo Rika Equipment Co., Ltd., SMP-21) is used for liquid flow, and sample liquid is collected using a fraction collector (EYELA Tokyo Rika Equipment Co., Ltd., DC-1500) for adsorption or elution. The metal concentration was measured using an induction plasma emission spectrometer ICP-AES (manufactured by Shimadzu Corporation: ICP-7000 Ver. 2). FIG. 4 shows the result of the breakthrough curve, and FIG. 5 shows the result of the elution curve.

4 is a breakthrough curve of platinum and rhodium in Example 3, and FIG. 5 is an elution curve of the eluent of Example 3.
As shown in FIG. V. = Begins breaking through around 100. V. = 500, saturation was reached, and rhodium was adsorbed, but started to break through immediately after the feed liquid was passed through, and hardly adsorbed. This is thought to be due to the slow adsorption rate of rhodium. In addition, the platinum adsorbent had no effect on the adsorption characteristics of the mixed ions other than platinum group metals, and showed selective adsorption characteristics for platinum and rhodium.
From FIG. 5, it was found that in elution, platinum can be concentrated to a maximum concentration of 2800 mg / L by using a 0.1 mol / L thiourea-1.0 mol / L hydrochloric acid solution. At this time, when the elution rate of platinum was calculated from the integral value of the breakthrough curve and the elution curve, it was found that 100% was eluted. B. V. = Rhodium was eluted by passing sulfuric acid through 30 to 1.0 mol / L sulfuric acid. However, the rhodium elution rate was 79%.
From the above, the platinum adsorbent has selective adsorption characteristics for platinum and rhodium, but it is understood that the adsorption of rhodium can be suppressed and platinum can be selectively adsorbed by setting the space velocity to 2.5 h ⁻¹ or more. It was. It was also found that platinum can be eluted at 100% by using a 0.1 mol / L thiourea-1.0 mol / L hydrochloric acid solution.

<Optimization of rhodium separation and recovery method>
Example 4
110 g of weakly basic anion exchange resin (Mitsubishi Chemical Corporation: Diaion WA-21) is prepared, 300 mL of 1 mol / L hydrochloric acid solution (manufactured by Wako Pure Chemical Industries, Ltd.), 300 mL of ion exchange water, 1 mol / L water Washing in the order of 300 mL of sodium oxide solution (manufactured by Wako Pure Chemical Industries, Ltd.) and 300 mL of ion-exchanged water, and after repeating this three times, using a vacuum dryer (manufactured by EYELA Tokyo Rika Co., Ltd .: VOS-201SD) The rhodium adsorbent was obtained by drying at 105 ° C. for 12 hours.
Next, 0.25 g of the rhodium adsorbent was mixed with 5 mol / L hydrochloric acid solutions 150, 250, 350, and 600 mL each containing 30 mg / L of rhodium, and a magnetic stirrer bar was set at a speed of 60 rpm in a 1 L Erlenmeyer flask. And shaken for 108 hours. After shaking, filtration was performed, and the metal concentration of the filtrate was measured in the same manner as in Example 1 to measure the time for the adsorption to reach saturation. The results are shown in Table 5 and FIG.
In addition, 0.25 g of rhodium adsorbent that reached saturation, 1.0 mol / L sodium chlorate-1.0 mol / L hydrochloric acid solution and 1.0 mol / L sodium chlorate-2.0 mol / L hydrochloric acid solution were added. 10, 20, 50, 150, and 250 mL were mixed, shaken for 48 hours, and rhodium was eluted to obtain an eluent. The eluent was filtered after shaking, and the metal concentration of the filtrate was measured. The metal concentration was measured in the same manner as in Example 1. The results are shown in Table 6.

(Comparative Example 1)
Prepare a column of 20 mm in inner diameter and 180 mm in length of the mini plant, and fill it with the rhodium adsorbent described in Example 4. The column is filled with glass wool, washed by passing ion-exchanged water, Deaerated.
Next, a 5 mol / L hydrochloric acid solution containing 30 mg / L of rhodium was prepared and passed through the column at a space velocity of 5.0 h- ¹ . The liquid flow was continued until rhodium adsorption reached saturation. The rhodium concentration in the hydrochloric acid solution after passing was measured in the same manner as in Example 1. The breakthrough curve at this time is shown in FIG.

6 is a diagram showing the influence of shaking time on rhodium adsorption, and FIG. 7 is a diagram showing a breakthrough curve of Comparative Example 1. FIG.
From FIG. 6, it was confirmed that the time required for rhodium adsorption to reach saturation required 48 hours regardless of the amount of liquid. Moreover, from FIG. 7, the rise of the breakthrough curve of Comparative Example 1 in which rhodium was adsorbed by the column method was very gradual. In addition, the time when rhodium adsorption reached saturation in the column method was January and a half.
From this, the adsorption rate in Example 4 which was adsorbed by the batch method was significantly improved compared to the time (1/2 months) when the adsorption of rhodium in Comparative Example 1 which was adsorbed by the column method reached saturation. You can see that In addition, it was shown that the adsorption rate can be 90% by shaking for 48 hours in the case of a supply liquid amount of 150 mL.

From Table 3, the concentration of concentration increased as the amount of the eluent decreased in both types of eluent. When a 1.0 mol / L sodium chlorate-1.0 mol / L hydrochloric acid solution was used, the maximum concentration concentration was 465 mg / L (about 15 times the supply solution concentration) when the amount of the eluent was 10 mL. In this case, however, the elution rate remained at 53%. On the other hand, when a 1.0 mol / L sodium chlorate-2.0 mol / L hydrochloric acid solution was used, the maximum concentration concentration was 812 mg / L (about 27 times the supply solution concentration) when the eluent amount was 10 mL, and the elution rate was Reached 92%.
From the above, it has become apparent that the batch method rather than the column method is more suitable for the separation and recovery of Rh with a rhodium adsorbent, and 1.0 mol / L sodium chlorate-2.0 mol / It has been found optimal to use L hydrochloric acid solution.

  Next, in order to optimize the mixing ratio of the rhodium adsorbent and the second separated and recovered leachate, 0.25 g of the rhodium adsorbent of Example 4 and a 5 mol / L hydrochloric acid solution containing 30 mg / L of rhodium were in a solid-liquid ratio. Each was mixed so that S / A = 0.4-4 g / L, and the magnetic stirrer bar was stirred at a speed of 60 rpm in a 1 L Erlenmeyer flask and shaken for 72 hours. After shaking, filtration was performed, and the metal concentration of the filtrate was measured in the same manner as in Example 1. The results are shown in FIG.

FIG. 8 is a relationship diagram of rhodium adsorption rate and solid-liquid ratio.
From FIG. 8, the adsorption rate increases as the solid-liquid ratio S / A increases, and when the solid-liquid ratio S / A exceeds 1.5 g / L, the rhodium adsorption rate becomes about 80 to 90% and 3 g / L. When L was exceeded, it was found that the adsorption rate of rhodium was 100%. From this, it was shown that rhodium can be adsorbed 100% when the solid-liquid ratio S / A of the rhodium adsorbent and the amount of leachate after the second separation and recovery is 3 g / L or more.

<Change in platinum group precipitation rate>
(Example 5)
Glass wool was packed into both ends of the palladium adsorbent (1.59 g) of Example 1 packed in a column having an inner diameter of 8 mm and a length of 100 mm. Next, after passing ion-exchanged water for washing and degassing, the 1 mol / L hydrochloric acid solution described in Example 1 was passed under conditions of a space velocity of 6.25 h ⁻¹ until the metal adsorption reached breakthrough. Then, the solution was washed again with ion-exchanged water, and finally a 1.5 mol / L ammonia solution was passed as an eluent to elute the adsorbed metal.
Next, 3 mL of the obtained palladium eluent was placed in a test tube, a 1 mol / L hydrochloric acid solution was added, and the mixture was allowed to stand overnight. Thereafter, the eluent is centrifuged at 3000 rpm for 5 minutes, separated into a precipitate and a supernatant, and the supernatant is measured for pH using a pH meter (manufactured by Horiba, Ltd.), and palladium at pH 1 to 7 The change in the precipitation rate of the precipitate containing was measured.

(Example 6)
The platinum eluent of Example 3 (about pH 1) The platinum eluent was centrifuged to separate the supernatant and the precipitate that was a complex of thiourea and platinum.
Next, 3 mL of the supernatant obtained by separation was placed in a test tube, a 1 mol / L aqueous sodium hydroxide solution was added, and the mixture was allowed to stand overnight. Thereafter, the eluate is centrifuged, and further separated into a precipitate and a supernatant. The supernatant is measured for pH using a pH meter (manufactured by Horiba, Ltd.), and a precipitate containing a platinum-containing precipitate at pH 1-12 is precipitated. The change in rate was measured.

(Example 7)
The rhodium eluent of Example 4 was centrifuged to separate the supernatant and the precipitate that was a complex of thiourea and rhodium.
Next, 3 mL of the supernatant obtained by separation is put into a test tube, heated to 80 ° C., 2 mol / L sodium hydroxide aqueous solution is added, filtered, and separated into a precipitate and a filtrate. The pH was measured using (manufactured by Horiba, Ltd.), and the change in the precipitation rate of the precipitate containing rhodium at pH 1 to 12 was measured.
The results of Examples 5 to 7 are shown in FIGS. The precipitation rate was calculated from the metal concentration in the eluent before precipitation and the metal concentration in the eluent after precipitation.

9 is a relationship diagram between pH and precipitation rate in Example 5, FIG. 10 is a relationship diagram between pH and precipitation rate in Example 6, and FIG. 11 is a relationship diagram between pH and precipitation rate in Example 7. .
From FIG. 9, it was found that in the case of the palladium eluent, the precipitation rate of the precipitate containing palladium exceeds 60% when the pH is less than 6, and the precipitation rate of the precipitate containing palladium becomes 100% when the pH approaches 1.
From FIG. 10, it was found that in the case of platinum eluent, there is a precipitation rate of 80% or more regardless of the pH, but the precipitation rate of the precipitate containing platinum is about 100% from when the pH exceeds 9. .
Further, from FIG. 11, in the case of rhodium eluent, the precipitation rate is 20% in the low pH region, and the precipitation rate is only about 50% even at pH 5, but when the pH exceeds 10, the precipitation rate of the precipitate containing rhodium is 100. It turned out to be%.
From the above, it was found that the platinum group metal can be efficiently recovered by setting the palladium eluent to a pH of less than 1 and the platinum eluent and the rhodium eluent to a pH of 10 or more.

  As described above, according to the present example, it has a high selectivity in the waste catalyst leachate in which other metals coexist, and the adsorption time which took one and a half months in the column method is dramatically improved to 48 hours. It became clear that platinum group metals could be separated and recovered from the solution.

  The present invention solves the above-mentioned conventional problems, and relates to a platinum group separation and recovery method for separating and recovering individual platinum group elements, particularly palladium, platinum and rhodium, from a platinum group mixture obtained from an automobile waste catalyst or the like. Without the agent, rhodium, which was difficult to recover in a short time, can be recovered selectively and in a short time without adjustment of additives, etc. Low environmental impact, excellent recovery efficiency for low-concentration metals such as palladium, platinum, and rhodium. Furthermore, the ion exchange method is used in each separation and recovery process, making operation easy and efficient. Since it can be recovered, and is excellent in workability, safe and simple, it is possible to provide a platinum group separation and recovery method that is low in cost and excellent in productivity.

Claims (6)

  (A) a leaching step of leaching a platinum group mixture composed of an automobile waste catalyst containing palladium, rhodium, platinum, etc. into a hydrochloric acid solution to prepare a leaching solution; and (b) a first leaching solution and a palladium adsorbent. A first separation / recovery step for separating and recovering the palladium by contacting in an adsorption separator; and (c) a first adsorption / recovery step packed in a second adsorption separator filled with a platinum adsorbent. A second separation and recovery step for separating and recovering the platinum by passing the leachate after separation and recovery at a high space velocity at which rhodium is not easily adsorbed; and (d) a second post-separation and recovery leachate after the second separation and recovery step; A rhodium adsorbent in a stirred adsorption tank, and a third separation and recovery step for separating and recovering the rhodium in a batch manner, and (e) the palladium adsorbent is a porous resin, Extraction supported on porous resin And an agent, (f) the platinum adsorbent and the rhodium adsorbent, separation and recovery method of platinum group which is a weakly basic ion exchange resin. The extractant is represented by the general formula R ₁ —S—R ₂ (wherein R ₁ and R ₂ are an alkyl group, an allyl group or an aryl group having 5 to 10 carbon atoms, and R ₁ and R ₂ are simultaneously hydrogen and The method for separating and recovering a platinum group according to claim 1, wherein the compound is represented by:   The method for separating and recovering a platinum group according to claim 1 or 2, wherein the porous resin is an ester-based synthetic adsorbent.   The method for separating and recovering a platinum group according to any one of claims 1 to 3, wherein the palladium adsorbent is not subjected to a hydrophilic treatment. 5. The platinum according to claim 1, wherein the second separation and recovery step is a column method, and the space velocity of the leachate after the first separation and recovery is 2 to 10 h ^−1. Tribe separation and recovery.   6. The solid-liquid ratio between the rhodium adsorbent amount in the third separation and recovery step and the amount of leachate after the second separation and recovery is 1.5 to 5 g / L. The platinum group separation and recovery method described in 1.

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