JP5629167B2 - Pt separation and recovery method - Google Patents

Description

  The present invention relates to a method for recovering Pt by efficiently separating these impurities from a Pt acidic solution containing heavy metals as impurities only by salt separation or, if necessary, by recrystallization after salt separation.

  Pt (platinum) is used as a material for a magnetic material, a fuel cell, and the like. However, since it is an expensive rare metal, Pt is recovered from waste such as a magnetic material and reused.

  As a method for obtaining high-purity Pt at a high recovery rate, for example, techniques of Patent Documents 1 to 3 are disclosed. Here, in order to obtain a crystallized product of Pt, a reaction is used in which ammonium chloride is added to an acidic solution containing chloroplatinic acid and Pt is precipitated as ammonium chloroplatinate. Among these, in Patent Document 1, after dissolving Pt-containing scraps with acid, the contaminants such as Co and Cr are removed by neutralization, and then precipitated as ammonium chloroplatinate to further increase the yield of Pt, so that it remains after the reaction. A method of adsorbing and removing Pt with an ion exchange resin and activated carbon is disclosed. In addition, Patent Document 2 discloses a method for removing these impurities by adjusting the acid concentration in the previous step in view of the fact that impurities of Te and Cu are precipitated in the Pt crystallization stage and the purity of Pt is lowered. Yes. Patent Document 3 discloses a method of removing impurities by subjecting them in advance to a two-step neutralization step before reacting a chloroplatinic acid solution containing impurities with ammonium chloride. Several kinds of metals such as Sn and Te are exemplified as impurities.

  Further, although not a method for recovering only Pt, Patent Document 4 discloses a method for recovering a platinum group element from an ion exchange resin adsorbed with a platinum group element such as Pt, Pd, and Ru by a roasting-acid leaching method. It is disclosed. Here, after ion-exchange resin is roasted in a specific oxidation-reduction atmosphere, it is leached under specific conditions, potassium chloride is added to the obtained leachate, and crystals of hexachloro complex salt containing platinum group elements are added. A method of producing and separating is disclosed.

JP 2003-129145 A JP-A-10-102156 JP 9-316560 A JP 2007-302944 A

  In the above-mentioned patent document, a technique for removing impurities such as Cu and Te contained in the hexachloro complex salt is disclosed. However, it is essential to add a process for removing impurities such as a neutralization process before the salt separation. Or when obtaining highly purified Pt only by salt separation, in the prior art, salt separation was generally performed several times. As described above, various methods for recovering Pt with high purity have been proposed, but all require special steps such as a neutralization step or multiple salt separations, and a simpler recovery technique is desired. . However, a technique for recovering Pt from a Pt acidic solution containing heavy metal by only one salt separation is not specifically disclosed.

  This invention is made | formed in view of the said situation, The objective is to provide the method of collect | recovering Pt efficiently from Pt acidic liquid containing a heavy metal only by salt separation.

The method for separating and recovering Pt according to the present invention is a method for separating and recovering Pt in a Pt acidic solution containing heavy metals as impurities as a potassium salt and / or an ammonium salt of chloroplatinic acid.
In the acid solution, the Pt acid solution containing the impurities, and potassium chloride and / or so that the molar ratio of potassium ions and / or ammonium ions to Pt in the acid solution is always within the stoichiometric ratio ± 10%. Or it has a summary in the place where ammonium chloride is added.

  Another Pt separation and recovery method according to the present invention has a gist in that, for example, water is further added to the potassium salt of chloroplatinic acid obtained by the above-described method and recrystallization is performed as a mother liquor. is there.

  According to the present invention, Pt can be efficiently recovered from a Pt acidic solution containing heavy metals as impurities by only one salt separation. If the method of this invention is used, since a heavy metal of high concentration can be efficiently separated from Pt, it is very useful.

FIG. 1 is a schematic diagram for explaining the addition method of the present invention. FIG. 2 is a schematic diagram for explaining a conventional addition method.

  In order to provide a method for efficiently recovering Pt from a Pt acidic solution containing heavy metals as impurities by only one salt separation, the present inventors, like the above-mentioned patent documents, convert Pt into water or acid. This study was based on the reaction of precipitation as crystals of hexachloro complex salt which is difficult to dissolve.

  As a result, instead of adding potassium chloride and / or ammonium chloride 2 into the Pt acidic solution 1 as in the prior art (see FIG. 2); as shown in FIG. A container is prepared, in which the molar ratio of potassium ions and / or ammonium ions (hereinafter sometimes collectively referred to as cations) to Pt in the acid solution 4 is always stoichiometric ratio ± By adding Pt acidic solution 1 and potassium chloride and / or ammonium chloride 2 (hereinafter, these may be collectively referred to as a cation supplying substance) so as to be within 10%, Pt acidic solution 1 Since impurities contained therein are diluted in the acid solution 4 to reduce the concentration, the potassium salt and / or ammonium salt of chloroplatinic acid (hereinafter collectively referred to as Pt salt). It is found that these are not involved in the production and can be separated efficiently, and further, impurities (for example, Ru) that form a complex with the cation and precipitate as in Pt are contained in the Pt acidic solution. Even when the cation is added, almost all of the added cation reacts with Pt, and the Pt salt precipitates in preference to the salt of Ru and cation (hereinafter sometimes referred to as Ru salt). As a result, it was found that Pt and Ru can be separated efficiently only by salt separation. In FIG. 1, for convenience, the acid solution in the container is described as dilute hydrochloric acid, but the present invention is not limited to this.

  Hereinafter, the method of the present invention will be described in detail.

  First, (a) an acid solution, (b) an acid-containing Pt acid solution, and (c) a cation supply material are prepared.

(A) Acid solution The acid solution is an aqueous solution of an inorganic acid commercially available for industrial use. The inorganic acid used in the present invention is not particularly limited, but an inorganic acid not containing an oxidizing agent (nitric acid, chlorine gas, etc.) is preferable because more Pt salt can be recovered without decomposition of the Pt salt. Furthermore, since the Pt salt is a hexachloro complex as described above, an inorganic acid containing chloride ions can be stably present, so that the Pt recovery rate is also improved, which is preferable. Therefore, hydrochloric acid is most preferable as the inorganic acid that satisfies the above two conditions. The acid concentration of the acid solution can be arbitrarily adjusted by adding water to the inorganic acid and diluting it. At that time, the acid concentration of the acid solution is determined so that the acid concentration at the time of producing the Pt salt falls within a preferable range of the acid concentration described later.

(A) Pt acidic solution containing impurities The Pt acidic solution is obtained by dissolving a Pt-containing material in an acid. The Pt-containing material contains impurities consisting of part or all of heavy metals represented by Co, Cr, Cu, Mo, Fe, Ni, Pb, Sn, Zn, W, Ru, and the like to be separated. . In addition, impurities such as rare earth elements such as Nd may be included. A typical example of the source of the Pt-containing material is a magnetic material containing Pt, for example. The composition of the magnetic material has been changed to include the various elements (impurities) described above with the recent technological development. However, if the method of the present invention is applied, efficient separation of many coexisting impurities is achieved. Is possible.

  Moreover, content of the heavy metal contained in Pt acidic liquid is not specifically limited. For example, when the above magnetic material is used as a raw material, the amount of heavy metal in the Pt acidic liquid is 150 to 200% by mass with respect to 100% by mass of Pt. Furthermore, the method of the present invention is a technique provided from the viewpoint of highly separating and removing heavy metals from a Pt acidic solution by only one salt separation, and depending on the Pt concentration, the Pt acidic solution contains Pt. Even if a large amount of heavy metal of 200% by mass or more is contained, Pt and heavy metal can be separated.

  Further, the amount of Pt contained in the Pt acidic solution is not particularly limited, but the Pt recovery rate is also related to the Pt concentration in the raw material solution, and considering that the higher the Pt concentration, the higher the Pt recovery rate. In general, it is preferable to treat an acidic liquid containing Pt of about 5 to 200 g / L (more preferably about 10 to 100 g / L) as a treatment target.

The acid used for the preparation of the Pt acidic solution is not particularly limited as long as it dissolves the Pt-containing raw material. For example, hydrochloric acid and aqua regia (concentrated hydrochloric acid and concentrated nitric acid 3 containing an oxidizing agent (chlorine gas etc.) are added. 1), and the like. Considering solubility and handling properties, it is preferable to use aqua regia. As the Pt acidic solution, in addition to a solution obtained by dissolving a Pt-containing material in aqua regia, a solution obtained by denitrating from an aqua regia solution can be used. Compared with aqua regia solution without denitration, the denitration solution does not decompose the generated Pt salt because the solution does not contain oxidant (nitric acid), improves the Pt recovery rate, and does not generate toxic NOx gas. There are advantages such as. In the Pt acidic solution, Pt exists as [PtCl ₆ ] ²⁻ (Pt hexachloroion).

(C) Cation supplying material As the cation supplying material for obtaining the Pt salt, potassium chloride and / or ammonium chloride can be used in the present invention. Specifically, it is preferable to select appropriately according to the required characteristics as follows. That is, when importance is attached to the improvement of the Pt recovery rate, it is preferable to use ammonium chloride. This is because ammonium chloride improves the Pt recovery rate than potassium chloride. On the other hand, when importance is attached to separation of Pt and Ru, use of potassium chloride is preferable. This is because the separation from Ru improves when Pt is precipitated as potassium chloroplatinate rather than Pt as ammonium chloroplatinate. Moreover, when adding a cation supply substance by dissolving in a solvent, the water which added the acid as a solvent can be used. The type of acid to be used is selected according to the type of the acid solution (a) or the acid solution Pt (a). Moreover, since the acid concentration at the time of Pt salt generation affects the separability from impurities as will be described later, the acid concentration when mixed with an acid solution or Pt acid solution is in a range suitable for the separation of impurities to be removed. To be determined in consideration.

  Next, the acid solution of (a) is put in a container, and the Pt acidic solution of (a) and the cation supply substance of (c) are added to obtain a Pt salt. In the addition, it is important that the molar ratio of the cation to Pt in the acid solution is always within a stoichiometric ratio of ± 10%, which improves the separation from impurities.

Here, Pt ([PtCl ₆ ] ²⁻ ) in the Pt acidic solution reacts with a salt containing a cation as shown in the following formula.
Reaction formula: [PtCl ₆ ] ^2- + 2AX → A ₂ [PtCl ₆ ] ^2- + 2X
_{^{(A = K +, NH 4}} +, X = Cl - , etc.)

That is, the stoichiometric ratio is 2 moles of cation with respect to 1 mole of Pt. In the present invention, during the Pt salt formation reaction (see the above reaction formula), Pt in the acid solution is Pt. The Pt acid solution and the cation supply substance are added to the acid solution so that the abundance ratio of cation and cation is always the above stoichiometric ratio. However, if the difference is within ± 10%, the effect described later is not affected. When the molar ratio of the cation to Pt exceeds the stoichiometric ratio + 10%, an excess of cation is present as described later, so that more Ru salt is produced and the purity of the resulting Pt salt is lowered.
On the other hand, when the molar ratio of the cation to Pt is less than the stoichiometric ratio of −10%, the recovery rate of the Pt salt is decreased and the Pt acidic solution is excessively present with respect to the cation. Impurities contained in the Pt acidic solution are easily involved during precipitation of the crystal nuclei of the Pt salt, and the purity of the obtained Pt salt is lowered.

  By adding in this way, the following three effects can be obtained. First, as a first effect, impurities contained in the Pt acidic solution are diluted before the Pt salt is produced, and a highly pure Pt salt can be obtained.

  The reason why impurities other than Ru are mixed into the Pt salt is not to form cations and salts as in the Ru salt, but to dissolve in the liquid when the crystal nucleus of the Pt salt precipitates in the initial stage of the Pt salt formation reaction. It is presumed that the impurities are involved in the state as it is. Therefore, if the concentration of impurities other than Ru is reduced in the initial stage of the Pt salt generation reaction, entrainment during the Pt salt generation is eliminated, and impurities other than Ru can be efficiently removed. On the other hand, it is considered that such entrainment does not occur at the stage after the crystal nucleus is deposited (= stage where the crystal grows from the nucleus). That is, since impurities other than Ru are present in a high concentration after the initial stage, they are not mixed in the Pt salt, and thus do not affect the separability from the impurities.

  In order to obtain the above effect, the Pt acidic solution and the cation supply substance are simultaneously added to, for example, a container containing an acid solution. Examples of the adding means include a method of adding each using a metering pump or a metering feeder. Also, considering the improvement in separation from impurities, the Pt acidic solution and the cation supply substance are added from a remote position with respect to the supply rate and supply time into the container, or gradually added over time during the addition. It is preferable to add. As a result, the impurities contained in the Pt acidic solution are diluted before the Pt salt is produced, and a highly pure Pt salt can be obtained.

  As a second effect, the production rate of the Pt salt can be controlled by controlling the addition rate of the Pt acidic solution and the cation supply substance. This is because the Pt salt formation reaction is fast, and the Pt salt formation reaction occurs immediately after contact between Pt in the Pt acidic solution and the cation in the cation supply material.

  As a third effect, since cations react preferentially with Pt over Ru, by adding them in the minimum amount (= stoichiometric ratio) necessary for the formation of the Pt salt, the Ru salt becomes As a result, Pt and Ru are efficiently separated.

  As soon as the addition of the Pt acidic solution is completed, the Pt salt formation reaction is completed. By adding an excessive amount of the cation supply substance after the completion of the reaction, the Pt salt dissolved in the liquid is precipitated by the common ion effect, and the Pt recovery rate is improved. However, since the Ru salt is precipitated when an excess cation is present as described above, the amount of the cation supply material to be added excessively, including the purity and recovery rate of the Pt salt, is the amount of Ru. Although it depends on the amount, it is generally preferable to control to about 0.2 to 0.5 times the stoichiometric ratio (that is, cation 0.4 to 1.0 mol with respect to 1 mol of Pt).

  As a preferable acid concentration at the time of producing the Pt salt, when the pH exceeds 2, impurities such as Mo and Fe precipitate as hydroxides, and the amount of impurities contained in the Pt salt increases. preferable. On the other hand, in order to further improve the separability from Ru, the acid concentration of the Pt acidic solution is preferably 2N or less. Since the Ru salt is less likely to be precipitated as a Ru salt as the acid concentration is lower, the separation from Ru is improved. In consideration of the above, the range of the preferred acid concentration for separating Pt is determined from the types of impurities contained in the Pt acid solution, and the acid solution, Pt acid solution, and cation supply are within that range. Determine the acid concentration of the substance.

  The reaction temperature (liquid temperature) is usually room temperature (about 20 ° C.). However, the higher the liquid temperature, the more difficult it is to separate from heavy metals such as Co, Cr and Fe. From the viewpoint of improving the separation from the impurity element, the temperature is preferably less than 60 ° C. The reason why the amount of the impurity element increases as the liquid temperature increases is unknown in detail, but the solubility of the Pt salt increases at a high liquid temperature, and the addition of the Pt acidic liquid and the cation supply substance is started. After that, the time at which the Pt salt starts to precipitate becomes slower than at low temperatures. Therefore, it is considered that when the Pt salt is precipitated, more impurity elements are present in the reaction solution, and these impurity elements are likely to be involved.

  On the other hand, in order to improve the separation from Ru, the temperature is preferably 40 ° C. or higher, more preferably 60 ° C. or higher. The reason why the separation from Ru is improved by increasing the liquid temperature is not clear in detail, but the solubility of Ru salt increases as the temperature increases, whereas the solubility of Pt salt does not increase as much as Ru salt. A difference in solubility is mentioned. Further, when the liquid temperature at the time of Pt salt generation is high, the precipitated Pt salt is considered to repeat redissolving and reprecipitation, which is presumed to reduce the amount of Ru coprecipitated with the Pt salt and improve the purity. The

  According to the present invention, a Pt salt with a low impurity concentration is deposited. That is, the method of the present invention is extremely useful as a method for efficiently separating Pt and impurities in a Pt acidic solution by only one salt separation.

  Thus, although the method of the present invention can obtain a sufficiently high purity Pt salt by only one salt separation, recrystallization may be performed thereafter for the purpose of further improving the purity of Pt. Specifically, after adding a solvent to the Pt salt obtained as described above, the solvent is heated to dissolve the entire amount of the Pt salt, including impurities, to obtain a mother liquor. Thereafter, the mother liquor is cooled, and the Pt salt is precipitated while the impurities remain in the mother liquor. As a result, a high-purity Pt salt with significantly reduced impurities can be obtained. Considering the purpose of recrystallization for obtaining a high-purity Pt salt, it is preferable to use potassium chloride as the cation supply substance. Hereinafter, preferred recrystallization methods used in the present invention will be described.

  In recrystallization, it is preferable to use water as a solvent. The reason why water is preferable is that the solubility of the Pt salt is higher than that of other solvents. Further, when Ru is contained as an impurity in the Pt acidic solution, the solubility of the Ru salt increases as the acid concentration decreases, so the use of water reduces the acid concentration of the mother liquor, and as a result, Ru remains in the mother liquor. , The amount of Ru in the Pt salt is decreased.

  Furthermore, in recrystallization, it is preferable to appropriately control the pH of the mother liquor depending on the type of impurities in the Pt acidic solution. Impurities other than Ru can be effectively removed by setting the pH of the mother liquor to 3 or less. When the pH of the mother liquor exceeds 3, Fe, Cr and the like begin to precipitate as hydroxides and coprecipitate with the Pt salt. On the other hand, when Ru is contained as an impurity, sufficient separation becomes possible by setting the pH of the mother liquor to 2 or more. However, when the acid concentration of the mother liquor is lowered and the pH exceeds 7, Ru is hydroxylated. And co-precipitated with Pt salt. In the present invention, when the pH of the mother liquor when the Pt salt is dissolved is out of the above range, the pH may be adjusted using hydrochloric acid, nitric acid, NaOH, KOH or the like (pH adjusting agent).

  In addition, the liquid temperature at the time of recrystallization (dissolution temperature of Pt salt) is preferably high, thereby improving the Pt recovery rate. This is because the higher the liquid temperature, the higher the solubility of the Pt salt, so that the amount of solvent required for dissolving the Pt salt can be reduced. Specifically, the liquid temperature is generally preferably in the range of 60 to 100 ° C, more preferably 80 to 100 ° C.

  In addition, it is preferable to add the cation supply substance (preferably potassium chloride) used for salt separation in the mother liquor to the mother liquor because the recovery rate of the Pt salt can be improved by the common ion effect. In this case, since the cation concentration in the filtrate after recrystallization is high, this used filtrate can be reused in the Pt salt separation step and used to produce Pt salt.

  After salt separation or recrystallization, Pt is recovered from the Pt salt by a known technique such as roasting or chemical reduction. Thus, by performing the above-mentioned recrystallization after the salt separation defined in the present invention, it is possible to remarkably suppress heavy metal contamination, which has been difficult to separate from Pt by conventional salt separation alone, and to achieve high purity Pt. Can be recovered.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples, and can be implemented with modifications within a range that can meet the purpose described above and below. They are all included in the technical scope of the present invention.

Example 1
In this example, ammonium chloride was used as the cation supply material.

(No. 1)
1 L of aqua regia was added to 90 g of Pt-containing material, heated and dissolved at 95 ° C., and then denitration was performed by heating while adding hydrochloric acid to obtain a Pt acidic solution containing the impurities shown in Table 1. The acid concentration at this time was 2N.

  Next, the Pt acidic solution obtained as described above and a 2.1 mol / L ammonium chloride solution were placed in a container containing 0.2 L of dilute hydrochloric acid using two metering pumps. The mixture was added so that the molar ratio of chloroplatinate ions and ammonium ions present in the liquid was always in the range of 1: 2 ± 10%, thereby precipitating ammonium chloroplatinate (Pt salt). As a result, the molar ratio of chloroplatinate ion to ammonium ion in dilute hydrochloric acid was 1.00: 1.90. After all the Pt acidic solution was added, only 0.8 mol of ammonium chloride solution was added to 1 mol of Pt. The total amount of ammonium chloride added is 2.8 moles per mole of Pt, and the molar ratio of ammonium ions to Pt is 1.4 times the stoichiometric ratio. Moreover, the liquid temperature at this time was 20 degreeC. The impurity concentration in the Pt salt thus obtained and the recovery rate of Pt are also shown in Table 1.

(No. 2 (comparison))
No. above. No. 1 in a container containing a Pt acidic solution using a metering pump. The ammonium chloride solution used in 1 was added to precipitate Pt salt crystals. The impurity concentration in the Pt salt thus obtained and the recovery rate of Pt are also shown in Table 1.

(No. 3 (comparison))
No. above. 1 except that the molar ratio of chloroplatinate ion and ammonium ion present in the liquid in the container was always 1: 4, and crystals of ammonium chloroplatinate (Pt salt) were precipitated. No. In the same manner as in Example 1, a Pt salt was precipitated. No. 3, the amount of ammonium chloride added was 4 moles per mole of Pt, and the molar ratio of ammonium ions to Pt was twice the stoichiometric ratio. The impurity concentration in the Pt salt thus obtained and the recovery rate of Pt are also shown in Table 1.

  From Table 1, No. was operated with the addition method and addition amount specified in the present invention. 1 shows that impurities in the Pt salt can be removed to a high degree and the Pt recovery rate is very high. On the other hand, No. which did not perform the addition method prescribed | regulated by this invention. 2 or No. 2 in which operation was performed exceeding the amount specified in the present invention. No. 3 has a good Pt recovery rate, but no. Compared to 1, the separation from impurities was inferior.

  Therefore, it was confirmed that the method of the present invention is extremely useful as a technique capable of highly separating the impurities coexisting in the Pt acidic solution only by salt separation.

Example 2
In this example, the operation was performed in the same manner as in Example 1 except that a Pt acidic solution that had not been denitrated after being dissolved in aqua regia was used. When the Pt acidic solution and the ammonium chloride solution were quantitatively added, the molar ratio of chloroplatinate ions and ammonium ions was 1.00: 2.15.

  These results are also shown in Table 2.

  From Table 2, the same results as in Example 1 were observed when a Pt acidic solution that was not denitrated was used as the Pt acidic solution. That is, No. 1 was operated with the addition method and addition amount specified in the present invention. 1, it was found that Ru and heavy metals in the Pt salt can be removed to a high degree and that the Pt recovery rate is also high. In addition, compared with Example 1 (Table 1) mentioned above, although the Pt collection | recovery rate of a present Example showed the slightly decreasing tendency, it is estimated that this originates in the kind of Pt acidic liquid. That is, when aqua regia is used as in this example, the Pt salt is decomposed by aqua regia, so the recovery rate of Pt is slightly reduced. When used, since such a decomposition phenomenon does not occur, it is considered that the recovery rate of Pt is increased. In addition, the fall of Pt collection | recovery rate by aqua regia use was also seen by the Example mentioned later (refer Table 4 and Table 5, Table 7 and Table 8, respectively).

Example 3
In this example, the operation was performed in the same manner as in Example 1 except that potassium chloride was used instead of ammonium chloride. When the Pt acidic solution and the potassium chloride solution were quantitatively added, the molar ratio of chloroplatinate ion to potassium ion was 1.00: 1.83.

  These results are also shown in Table 3.

  From Table 3, the same results as in Example 1 were observed when potassium chloride was used instead of ammonium chloride. However, compared to Example 1 described above, the Pt recovery rate of the present example was slightly lowered, because ammonium chloride and the salt produced are less soluble in the reaction solution. Therefore, it is understood that the use of ammonium chloride is preferable when it is desired to ensure not only the separation from impurities but also the higher Pt recovery rate by salt separation. The effect of improving the Pt recovery rate by using ammonium chloride was also observed in Examples described later (see Tables 4 and 6, and Tables 7 and 9 respectively). On the other hand, it can be seen from the comparison of the Ru concentrations of Example 1 and Example 3 that the effect of removing Ru is higher in potassium chloride. That is, Example 1 and Example 3 use the same Pt acidic solution as a raw material, but No. 1 in Table 1 and Table 3 shows. When comparing 1, Ru in Table 1 is reduced to 150 ppm with respect to Pt, whereas in Table 3, it is 80 ppm with respect to Pt, which is about half that of Table 1. In addition, the improvement of Ru removal rate by use of potassium chloride was also seen in Examples described later (see Tables 4 and 6, and Tables 7 and 9, respectively).

Example 4
In this example and Examples 5 and 6 to be described later, the liquid temperature at the time of reaction (at the time of addition) was changed in the range of 10 to 80 ° C. as shown in Table 4, and the Pt salt was precipitated. No. of Example 1 except that the temperature was returned to room temperature (20 ° C.). The same operation as in No. 1 was performed. When the Pt acidic solution and the ammonium chloride solution were quantitatively added, the molar ratio of chloroplatinate ions to ammonium ions was 1.00: 1.89. The acid concentration of the reaction solution is 2N.

  These results are also shown in Table 4. For reference, Table 4 shows No. 1 of Example 1 described above. The result of 1 (liquid temperature 20 ° C.) is also shown.

  From Table 4, the higher the liquid temperature at the time of the reaction, the more Ru amount in the Pt salt can be reduced. When the liquid temperature is 40 ° C., the Ru amount in the Pt salt can be reduced to 90 ppm, and the liquid temperature is 80 When it reached 0 ° C., the amount of Ru in the Pt salt could be remarkably reduced to 13 ppm. On the other hand, for heavy metals other than Ru, when the liquid temperature was 60 ° C. or higher, the amount of heavy metal in the Pt salt increased. Therefore, it is recommended that the liquid temperature during the reaction be appropriately controlled according to the type of impurities contained in the Pt acidic liquid. In addition, about the recovery rate of Pt, the big influence by liquid temperature was not seen, but the very high recovery rate was obtained at any temperature.

Example 5
In this example, the liquid temperature at the time of addition was changed in the range of 10 to 80 ° C. as shown in Table 5, and after depositing the Pt salt, the liquid temperature was returned to room temperature (20 ° C.). No. 2 in Example 2 The same operation as in No. 1 was performed. When the Pt acidic solution and the ammonium chloride solution were quantitatively added, the molar ratio of chloroplatinate ions to ammonium ions was 1.00: 2.08. The acid concentration of the reaction solution is 2N.

  These results are also shown in Table 5. For reference, Table 5 shows No. 2 of Example 2 described above. The result of 1 (liquid temperature 20 ° C.) is also shown.

  From Table 5, when the kind of Pt acidic liquid was changed to aqua regia, the same result as the said Example 4 was seen. That is, the higher the liquid temperature during the reaction, the more the amount of Ru in the Pt salt can be reduced. On the other hand, impurities other than Ru tended to increase when the liquid temperature was 60 ° C. or higher. . As for the Pt recovery rate, the Pt recovery rate decreased significantly as the liquid temperature increased. This is presumably because the higher the liquid temperature, the easier the decomposition reaction of the Pt salt by aqua regia proceeds.

Example 6
In this example, the liquid temperature at the time of addition was changed in the range of 10 to 80 ° C. as shown in Table 6, and after depositing the Pt salt, the liquid temperature was returned to room temperature (20 ° C.). No. 3 in Example 3 The same operation as in No. 1 was performed. When the Pt acidic solution and the potassium chloride solution were quantitatively added, the molar ratio of chloroplatinate ions to potassium ions was 1.00: 2.00. The acid concentration of the reaction solution is 2N.

  These results are also shown in Table 6. For reference, Table 6 shows No. 3 of Example 3 described above. The result of 1 (liquid temperature 20 ° C.) is also shown.

  From Table 6, the same results as in Example 4 were observed when potassium chloride was used instead of ammonium chloride. That is, the higher the liquid temperature during the reaction, the more the amount of Ru in the Pt salt can be reduced. On the other hand, impurities other than Ru tended to increase when the liquid temperature was 60 ° C. or higher. . In addition, about the recovery rate of Pt, the big influence by liquid temperature was not seen, but the very high recovery rate was obtained at any temperature.

Example 7
In this example and Examples 8 and 9 described later, the case where the acid concentration during the reaction (during addition) is changed will be described.

  Specifically, except that the liquid temperature at the time of addition was 40 ° C., the acid concentration was variously changed as shown in Table 7 to precipitate the Pt salt, and then the liquid temperature was returned to room temperature (20 ° C.). No. 1 in Example 1 The same operation as in No. 1 was performed. The molar ratio of chloroplatinate ions and ammonium ions when the Pt acidic solution and ammonium chloride solution were quantitatively added was 1.00: 2.02. The acid concentration was variously adjusted using hydrochloric acid or sodium hydroxide.

  These results are also shown in Table 7. For reference, the results of Example 4 (liquid temperature 40 ° C.) described above are also shown in Table 7.

  From Table 7, if the acid concentration during the reaction was controlled to 2N or less, the Ru amount in the Pt salt could be reduced, and the Ru amount tended to decrease more and more as the acid concentration decreased. It was also found that the amount of impurities other than Ru can be reduced. However, when the pH reached about 9, impurities were precipitated together with the Pt salt as hydroxides. The Pt recovery rate was not significantly affected by the acid concentration, and an extremely high recovery rate was obtained at any acid concentration.

Example 8
In this example, the liquid temperature at the time of addition was 40 ° C., and the acid concentration at the time of addition was variously changed as shown in Table 8 to precipitate the Pt salt, and then the liquid temperature was returned to room temperature (20 ° C.). Except for this, No. 2 in Example 2 The same operation as in No. 1 was performed. When the Pt acidic solution and the ammonium chloride solution were quantitatively added, the molar ratio of chloroplatinate ions to ammonium ions was 1.00: 2.10.

  These results are also shown in Table 8. For reference, Table 8 also shows the results of Example 5 (liquid temperature 40 ° C.) described above.

  From Table 8, the same results as in Example 7 were observed when the type of Pt acidic solution was changed to aqua regia. That is, it was found that if the acid concentration during the reaction was controlled to 2N or less, the amount of Ru in the Pt salt and the amount of impurities other than Ru could be reduced, and at pH 9, impurities were precipitated together with the Pt salt. As for the recovery rate of Pt, as in Example 7, there was no significant effect due to the acid concentration. The Pt recovery rate was slightly reduced as compared with Example 7 described above, which is presumed to be due to the progress of the decomposition reaction of the Pt salt by aqua regia.

Example 9
In this example, the liquid temperature at the time of addition was 40 ° C., and the acid concentration at the time of addition was variously changed as shown in Table 9 to precipitate the Pt salt, and then the liquid temperature was returned to room temperature (20 ° C.). Except for this, No. of Example 3 The same operation as in No. 1 was performed. When the Pt acidic solution and the potassium chloride solution were quantitatively added, the molar ratio of chloroplatinate ions to potassium ions was 1.00: 1.99.

  These results are also shown in Table 9. For reference, Table 9 also shows the results of Example 6 (liquid temperature 40 ° C.) described above.

  From Table 9, the same results as in Example 7 were observed when potassium chloride was used instead of ammonium chloride. That is, it was found that if the acid concentration during the reaction was controlled to 2N or less, the amount of Ru in the Pt salt and the amount of impurities other than Ru could be reduced, and at pH 9, impurities were precipitated together with the Pt salt.

Example 10
In this example, an operation was performed to confirm the effect of recrystallization. Specifically, 31 mL of water was added to 1 g of Pt salt obtained in Example 9 with an acid concentration of 2.0 N (= 40 ° C. in Example 6) and heated to 80 ° C. to completely dissolve the Pt salt. After that, the pH of the solution (mother liquor) was measured, and the pH of the solution was adjusted to 3 using hydrochloric acid or sodium hydroxide. Thereafter, the solution was cooled to room temperature to reprecipitate the Pt salt. Further, during the cooling, potassium chloride powder was added so that the molar ratio of potassium ions to 30 mol of Pt was 30 mol.

  The impurity concentration in the Pt salt thus obtained and the recovery rate of Pt are shown in Table 10. In Table 10, Pt recovery rate is Pt recovery rate in salt separation before recrystallization, Pt recovery rate in recrystallization, and recovery rate of Pt from Pt acid solution to recrystallization (this is shown in parentheses) ).

  From Table 10, it was confirmed that when recrystallization was performed under the preferable conditions of the present invention, the Pt purity after recrystallization was improved.

1 Pt acidic solution 2 Potassium chloride and / or ammonium chloride 3 Stirrer 4 Dilute hydrochloric acid

Claims (2)

In a method for separating and recovering Pt in a Pt acidic solution containing heavy metal as an impurity as a potassium salt and / or an ammonium salt of chloroplatinic acid,
In the acid solution, the Pt acid solution containing the impurities, and potassium chloride and / or so that the molar ratio of potassium ions and / or ammonium ions to Pt in the acid solution is always within the stoichiometric ratio ± 10%. Alternatively, a method for separating and recovering Pt, comprising adding ammonium chloride.   A method for separating and recovering Pt, wherein water is further added to the potassium salt of chloroplatinic acid obtained by the method according to claim 1 to perform recrystallization as a mother liquor.