KR101950110B1 - Separation method of paladium and platium - Google Patents

Abstract

The present invention relates to a method for effectively separating platinum and palladium by selectively extracting the palladium through a solvent extraction method and easily removing the palladium from an extraction agent in which the palladium is extracted. According to the present invention, the method comprises the following steps of: selectively extracting palladium (Pd) by using dialky1dithiophosphinic acid from an extract containing platinum (Pt) and palladium (Pd); and separating the palladium (Pd) from an extraction agent in which the palladium (Pd) is extracted with aqua regia.

Description

{SEPARATION METHOD OF PALADIUM AND PLATIUM}

The present invention relates to a separation method of platinum and palladium, and more particularly, to an extraction system capable of efficiently and selectively extracting palladium and a system capable of removing palladium from palladium- And palladium can be separated with excellent efficiency.

Palladium (Pd) and platinum (Pt) are widely used in the manufacture of advanced materials with special functions. However, in order to recover palladium (Pd) and platinum (Pt) in ore or secondary resources in high purity, the two metals must be separated from each other.

For this purpose, the solvent extraction method, ion exchange method, and precipitation method are used for the leaching solution containing platinum (Pt) and palladium (Pd). Especially, the leaching solution containing platinum (Pt) and palladium (Pd) Many studies have been made to separate metals.

However, since the extraction behaviors of platinum (Pt) and palladium (Pd) are very similar to the solvent extracting agent, it is difficult to separate platinum (Pt) and palladium (Pd) by solvent extraction.

In this regard, a lot of research has been conducted to find an extraction system for selectively extracting Pt (IV) or Pd (II) contained in a hydrochloric acid solution. As a result, LIX 84I, LIX 63, DOS, CyphosIL 101, CyphosIL 104 can be used as selective extractants of Pt (IV) or Pd (II).

However, these extractants have problems such as excessively high cost, slow extraction rate, low separation factor between Pd (II) and Pt (IV).

Korean Patent Publication No. 2000-0046770

In order to separate platinum (Pt) and palladium (Pd) by the solvent extraction method, it is necessary to efficiently extract the extracted platinum (Pt) or palladium (Pd) It is an object of the present invention to provide a separation method of platinum and palladium capable of efficient stripping together with excellent selective extraction.

In order to solve the above problems, the present invention provides a method for separating platinum (Pt) and palladium (Pd) from a hydrochloric acid leaching solution containing platinum (Pt) and palladium (Pd), wherein the dialkyldithiophosphonic acid (Pd) is extracted from the extractant from which the palladium (Pd) has been extracted by using a royal flush using an extraction agent containing dialkyldithiophosphinic acid And palladium.

According to the method of the present invention, only palladium (Pd) can be selectively and efficiently extracted at various concentrations of hydrochloric acid containing platinum (Pt) and palladium (Pd), and palladium (Pd) can be extracted from the extractant containing palladium Pd) can be completely removed, and the platinum (Pt) and the palladium (Pd) can be efficiently separated.

Fig. 1 shows the name, structure and chemical formula of the solvent extractant used in Examples and Comparative Examples of the present invention.
FIG. 2 shows the effect of hydrochloric acid concentration on Pd (II) extraction using D2EHPA, PC88A, Cyanex 272, Cyanex 301, LIX 63 and LIX 84I as extractants, wherein the leach solution contains Pd 100 mg / / A = 1, diluent is kerosene).
Figure 3 shows the effect of hydrochloric acid concentration on the extraction of Pd (II) using TBP, Cyanex 923, TOA and Alamine 336 as extractants, wherein the leach solution contains Pd 100 mg / L, O / A = 1, Kerosene).
4 shows the effect of hydrochloric acid concentration on Pt (IV) extraction using D2EHPA, PC88A, Cyanex 272, Cyanex 301, LIX 63, LIX 84I, TBP, Cyanex 923, TOA and Alamine 336 as extractants , 100 mg / L of Pt, O / A = 1, and kerosene as a diluent).
FIG. 5 shows the effect of hydrochloric acid concentration on the extraction of Pt (IV) and Pd (II) using LIX 63, wherein the leach solution contains 100 mg / L of Pt, 100 mg / , The diluent is kerosene).
Figure 6 shows the effect of hydrochloric acid concentration on the extraction of Pt (IV) and Pd (II) using Cyanex 301, where the leach solution was 100 mg / L of Pt, 100 mg / L of Pd, , The diluent is kerosene).
FIG. 7 shows the effect of LIX 63 concentration on the extraction of Pd (II) (here, Pd 100 mg / L, O / A = 1, and diluent kerosene).
FIG. 8 shows the effect of concentration of Cyanex 301 in extracting Pd (II) (where Pd 100 mg / L, O / A = 1, diluent is kerosene).
Fig. 9 is a process diagram showing the steps of a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. Also, when a part is referred to as " including " an element, it does not exclude other elements unless specifically stated otherwise.

The present inventors have found that when using the following solvent extraction and stripping system, platinum (Pt) and palladium (Pd) can be separated at a higher efficiency than the conventional method, leading to the present invention.

The method according to the present invention comprises selectively extracting palladium (Pd) using an extractant containing dialkyldithiophosphinic acid in a hydrochloric acid leaching solution containing platinum (Pt) and palladium (Pd) And removing palladium (Pd) from the extractant from which the palladium (Pd) has been extracted by using aqua regia.

In the hydrochloric acid leach solution, the concentration of the hydrochloric acid is preferably 0.1 M or more, more preferably 0.5 to 9 M, in order to increase extraction efficiency of the extractant.

The optimum concentration of the extractant depends on the initial palladium concentration, and maintaining the concentration of the extractant at 0.01-0.02 M for 100 ppm of palladium can selectively extract palladium (Pd) to achieve high separation efficiency When the concentration of the extracting agent is more than 0.02M, it is preferable to maintain the above range because platinum (Pt) is partially extracted and the separation efficiency decreases.

It is preferable to use the diluted water at a rate of 2 times or less because the efficiency of stripping decreases when water is diluted 3 times or more with water (distilled water or deionized water).

The extractant may be Cyanex 301 (Bis (2,4,4-trimethylpentyl) dithiophosphinic acid).

[Example]

Fig. 1 shows the name, structure and chemical formula of the solvent extractant used in Examples and Comparative Examples of the present invention. These solvent extractants were used without further purification and kerosene from Daejung Chemicals & Metals was used as a diluent.

The solvent extraction and stripping processes were carried out by mixing the same volume (10 mL) of the organic phase and the aqueous phase, stirring with a stirrer for 30 minutes (extraction and stripping equilibrium reached within 30 minutes in the initial test) , All of which were carried out at room temperature (25 ± 1 ° C).

The metal ion concentration in the aqueous solution before and after the extraction was measured using an ICP-AES instrument, and the metal ion concentration in the organic phase from which the metal ions were extracted was calculated as the mass balance.

Through the solvent extraction test, the extraction rate and the removal rate of each component were calculated through the following [Formula 1] and [Formula 2].

[Formula 1]

(%) = (Metal equilibrium mass in organic phase) / (initial metal mass in aqueous solution before extraction) x 100

[Formula 2]

Removal rate (%) = (metal equilibrium mass in aqueous solution after removal) / (initial metal mass in organic phase before removal) x 100

The separation factor is derived from [Equation 3] below.

[Formula 3]

Separation Factor (?) = D _M1 / D _M2

(Where D _M1 is the distribution ratio of the M1 metal, D _M2 is the distribution ratio of the M2 metal, and the distribution ratio is the ratio of the metal concentration present in the organic phase to the metal concentration present in the aqueous phase at the equilibrium)

Effect of hydrochloric acid concentration on leaching solution

Since the concentration of Pd (II) contained in the leach solution of the secondary resource is about 50 to 500 mg / L, the concentration of Pd (II) in this embodiment is 100 mg / L, The effect of hydrochloric acid (HCl) concentration was confirmed.

According to the distribution of Pd (II) in hydrochloric acid solution, most of Pd (II) exists as PdCl ₄ ^2- when the concentration of hydrochloric acid is higher than 0.1M. That is, most of Pd (II) exists as anion complex in strong hydrochloric acid solution.

In order to evaluate the possibility of extracting Pd (II) present as an anion complex, organic solvent extractants having the concentrations shown in Table 1 below were used.

Extractant density Cyanex 301 0.02M LIX63 0.02M TOA 0.02M Alamine 336 0.02M D2EHPA 0.5M PC88A 0.5M Cyanex 272 0.5M LIX84I 0.5M TBP 0.5M Cyanex 923 0.5M

In Table 1, it is known that Pd (II) is well extracted in the case of Cyanex 301, LIX 63, TOA and Alamine 336. The concentration of the extractant was fixed at 0.02M and the relatively low extractability of D2EHPA, PC 88A , Cyanex 272, LIX 84I, TBP and Cyanex 923 were fixed at 0.5M. In this extraction step, the volume ratio of the organic phase to the aqueous phase (O / A) was set to 1.

Fig. 2 shows the change in the extraction rate of Pd (II) with the concentration of hydrochloric acid when using a cationic extractant.

As shown in FIG. 2, the extraction rate of Pd (II) by D2EHPA, PC88A and Cyanex 272 was negligible in the hydrochloric acid concentration range of 0.5-9M. On the other hand, Cyanex 301 showed the most Pd (II) extraction in the total hydrochloric acid concentration range. On the other hand, in the case of LIX 63, the extraction rate gradually decreased as the hydrochloric acid concentration increased from 0.5M to 5M, but the extraction rate decreased sharply above 5M. In addition, the extraction rate of Pd (II) by LIX 84I was much lower than that of LIX 63 and gradually decreased with increasing hydrochloric acid concentration.

That is, although the acid dissociation constant of the used cationic extractant was slightly different, it was confirmed that complete extraction of Pd (II) was possible when Cyanex 301 was used even in 9M strong hydrochloric acid solution. This is because the functional group of Cyanex 301 is thiophosphoryl group (-PSSH), while the functional groups such as D2EHPA, PC88A and Cyanex 272 are phosphate group (-POOH), sulfur (S) belongs to soft base and oxygen It becomes a hard base. According to the HSAB theory, Pd (II) is classified as a soft acid and can form stronger bonds with the soft base. As a result, Pd (II) tends to form complex with the functional group of Cyanex 301, .

Figure 3 shows the effect of HCl concentration on the extraction of Pd (II) by TBP, Cyanex 923, TOA and Alamine 336.

As shown in FIG. 3, the extraction rate of Pd (II) by Cyanex 923 was found to be complete between 0.5M and 3M, and the extraction rate rapidly decreased to 75% as the hydrochloric acid concentration increased. In contrast, the extraction rate of TBP was negligible. In the case of TOA and Alamine 336, the extraction of Pd (II) was mostly performed at 0.5M to 3M of hydrochloric acid concentration, and the extraction rate was remarkably decreased to 40% as the hydrochloric acid concentration was increased.

From the above results, it is confirmed that LIX 63, LIX 84 I, Cyanex 923, Cyanex 301, TOA, Alamine 336 and the like can be used for the extraction of Pd (II).

Selective extraction of Pd (II)

For the separation of platinum (Pt) and palladium (Pd), the extraction of palladium (Pd) should be efficient and the extraction of platinum (Pt) should be limited or not nearly done.

To this end, the extractability of the extractants to Pt (IV) was evaluated in a synthesis solution containing only Pt (IV).

In this test, the concentration of Pt (IV) was fixed at 100 mg / L, the concentration of these extracts was fixed at 0.1M, and the volume ratio of organic phase and water phase (O / A) was 1.

Figure 4 shows the change in the extraction rate of Pt (IV) in the leach solution with a hydrochloric acid concentration of 0.5M to 9M when various extractants were used.

As shown in FIG. 4, the extraction rate of Pt (IV) by Cyanex 923 was 83 to 95%. Regardless of the concentration of hydrochloric acid, the extraction rate of Pt (IV) was 100% for TOA and Almaine 336. On the other hand, the extraction rate of Pt (IV) by Cyanex 301 tended to decrease from 30% to 10% as the concentration of hydrochloric acid increased. For the other extractants Cyanex 272, D2EHPA, PC 88A, LIX 63 and LIX 84I, the extraction rate tended to increase slightly when the hydrochloric acid concentration was increased from 0.5M to 9M, but Pt (IV) was scarcely extracted.

4 shows that Cyanex 301 or LIX 63, which is an extraction agent having a high extraction rate of Pd (II) and a low extraction ratio of Pt (IV), may be used as a selective extractant for Pd (II) to Pt .

Thus, solvent extraction experiments were performed using mixed solutions containing Pd (II) and Pt (IV) using Cyanex 301 and LIX 63.

In this test, the concentrations of Pd (II) and Pt (IV) were fixed at 100 mg / L, and LIX 63 and Cyanex 301 were used at two concentrations of 0.01M and 0.02M, respectively. / A) was set to 1.

Fig. 5 shows the results of extraction tests of Pd (II) and Pt (IV) using LIX 63.

As shown in FIG. 5, the extraction rate of Pd (II) slightly decreased from 97% and 83% to 82% and 73%, respectively, as the hydrochloric acid concentration increased from 0.5M to 5M, and when the hydrochloric acid concentration increased to 9M The extraction rate of Pd (II) tends to decrease sharply. In contrast, the extraction rate of Pt (IV) was substantially 0% under the above conditions.

6 shows the extraction test results of Pd (II) and Pt (IV) using Cyanex 301.

As shown in FIG. 6, Pd (II) was extracted close to 100% in all the conditions tested, but Pt (IV) was not extracted at all.

Table 2 below shows the separation coefficients between Pd (II) and Pt (IV) by Cyanex 301 and LIX 63 derived from the above results.

HCl concentration
(M) The separation factor D _{Pd (II)} / D _{Pt (IV} ) Cyanex 301 Concentration (M) LIX 63 Concentration (M) 0.5 1414 2931 664 2123 1.0 1139 2113 580 953 3.0 1178 1847 440 633 5.0 1241 2319 405 223 7.0 1455 2271 50 40

(D _{Pd (II)} is the distribution ratio of Pd (II), D _{Pt (IV)} is the distribution ratio of Pt (IV)

As shown in Table 2, the separation factor between two metals by Cyanex 301 was higher than that by LIX 63 in the same extraction test.

In addition, the separation factor by Cyanex 301 was almost constant when the concentration of hydrochloric acid was changed from 0.5M to 9M, but the separation coefficient by LIX 63 tended to decrease with increasing hydrochloric acid concentration.

In other words, Cyanex 301 is an excellent extractant from LIX in view of selective extraction of Pd (II) to Pt (IV).

Extractant concentration effect

In this test, the extraction rates of LIX 63 and Cyanex 301 were checked at various concentrations of hydrochloric acid. The concentration of Pd (II) was fixed at 100 mg / L, and the volume ratio (O / A) of the organic phase to the aqueous phase was changed to 1M, 5M and 9M 1.

Fig. 7 shows the change in the extraction rate of Pd (II) according to the concentration change of LIX63.

As shown in FIG. 7, the hydrochloric acid concentration had a significant effect on the Pd (II) extraction by LIX 63. When the hydrochloric acid concentration was 1 and 5 M, the extraction rate of Pd (II) As the concentration increased from 0.003M to 0.015M, it increased to 88% and remained constant even though the LIX 63 concentration was further increased. On the other hand, when the concentration of hydrochloric acid was 9M, the extraction rate of Pd (II) by LIX 63 was much smaller than that at 1M and 5M HCl. In other words, it is not preferable to use LIX 63 in terms of extraction efficiency, since complete extraction of Pd (II) by LIX 63 is difficult under conditions of a hydrochloric acid concentration of 9M or more.

FIG. 8 shows the change in the extraction rate of Pd (II) according to the concentration change of Cyanex 301.

As shown in FIG. 8, the Cyanex 301 concentration rapidly increased from 10% to 100% as the concentration increased from 0.003M to 0.01M, and then remained constant even when the concentration of Cyanex 301 increased to 0.05M. That is, Cyanex 301 can completely extract Pd (II) from various concentrations of hydrochloric acid solution. In addition, no production of the third phase was observed in the extraction process of Cyanex 301.

Removal of Pd (II)

Since the ease of removal of the metal extracted in the solvent extraction process directly affects the re-use efficiency of the extractant, it is very important that the removal of the metal is easy to achieve an efficient process.

As can be seen from the results in Table 2, in view of the selective extraction of Pd (II) with respect to Pt (IV), Cyanex 301 is an excellent extracting agent compared to LIX 63.

However, it is very difficult to remove Pd (II) from Cyanex 301 compared with Pd (II) removal from LIX 63 from which Pd (II) is extracted. (IV) and Pd (II) can be completely removed from LIX 63 under the condition that the hydrochloric acid concentration is lower than 7M since thiourea (thiourea, (NH ₂ ) ₂ CS) For extraction, LIX 63 may be a good choice, but if the concentration of hydrochloric acid is higher than 7M, the extraction rate of Pd (II) by LIX 63 sharply decreases. Thus, for complete extraction of Pd (II) An extraction step is required, which is not preferable from the viewpoint of process efficiency.

Therefore, the present inventor carried out stripping tests on various materials in order to realize a stripping process capable of efficiently stripping Pd (II) from Cyanex 301 extracted from Pd (II).

In the stripping test of Cyanex 301, Pd (II) was extracted by contacting 0.02M of Cyanex 301 extractant with a 5M hydrochloric acid concentration solution containing 100 mg / L Pd (II). At this time, the volume ratio (O / A) of the organic phase to the aqueous phase was 1. As a result, an extractant having a concentration of Pd (II) of 97.5 mg / L in Cyanex 301 was obtained.

Table 3 below shows the types and removals (%) of materials tested to remove Pd (II) from Cyanex 301 from which Pd (II) was extracted.

Removal agent Removal rate (%) Remarks HCl 10 M 1.5 Comparative Example HCl 10.5 M 3.0 Comparative Example HCl 11.3 M 5.1 Comparative Example H2SO4 13 M 4.3 Comparative Example H2SO4 14 M 5.3 Comparative Example H2SO4 15 M 6.3 Comparative Example H2SO4 16 M 7.8 Comparative Example H2SO4 17.8 M 9.8 Comparative Example HNO3 11 M 5.1 Comparative Example HNO3 12 M 5.5 Comparative Example HNO3 13 M 6.3 Comparative Example HNO3 14.6 M 7.5 Comparative Example HClO4 10 M 3.5 Comparative Example HClO4 11 M 3.8 Comparative Example HClO4 12.3 M 4.1 Comparative Example 7.0 M HClO ₄ + 0.5MHCl 1.6 Comparative Example 0.5 M NaSCN 1.4 Comparative Example 0.5 M (NH ₂ ) ₂ CS 2.5 Comparative Example 0.1 M HCl + 0.5 M (NH ₂ ) ₂ CS 1.9 Comparative Example 1.0 M HCl + 0.1 M (NH ₂ ) ₂ CS 2.7 Comparative Example 0.1 M Oxalic acid 1.4 Comparative Example 5.0 M HCl + 5% H ₂ O ₂ 1.1 Comparative Example 0.1 M Oxalic acid + 5% H ₂ O ₂ 1.8 Comparative Example 1.0 M Ascorbic acid + 0.5 M HCl 2.3 Comparative Example 1.0 M Hydrazine + 0.5 M (NH ₂ ) ₂ CS 1.7 Comparative Example 0.1 M Na ₂ S ₂ O ₃ + 1M (NH ₂ ) ₂ CS 2.5 Comparative Example _{0.1 M Na 2 CO 3 + 0.1M} (NH 4) 2 CO 3 + 0.1MOxalicacid 1.5 Comparative Example (A / O = 1: 1) 99 Example (A / O = 2: 1) 100 Example (A / O = 3: 1) 100 Example (A / O = 5: 1) 100 Example (A / O = 7: 1) 100 Example

In Table 3, the royal flue is the result of using two times diluted with distilled water.

As shown in Table 3, among the various substances capable of providing electrons to the sulfur atom of Cyanex 301 and capable of bonding with Pd (II) of the organic extracting agent, only the number of kinetics achieved a removal rate of 99% or more, In the example, the removal rate of Pd (II) was negligible.

9, when Cyanex 301 is used as a hydrochloric acid leaching solution containing Pd (II) and Pt (IV), only Pd (II) can be selectively extracted with high efficiency. Cyanex 301 can be used to remove Pd (II) completely, thus enabling efficient reuse of the extractant Cyanex 301.

It is possible to efficiently separate palladium (Pd) and platinum (Pt) through a system including such extraction and stripping processes.

Claims (8)

As a method for separating platinum (Pt) and palladium (Pd) from hydrochloric acid leaching solution containing platinum (Pt) and palladium (Pd)
Selectively extracting palladium (Pd) using an extractant containing Cyanex 301 (Bis (2,4,4-trimethylpentyl) dithiophosphinic acid)
And separating the palladium (Pd) from the extraction agent from which the palladium (Pd) has been extracted using a royal flush. The method according to claim 1,
Wherein the concentration of hydrochloric acid is 0.1 M or more. The method according to claim 1,
Wherein the concentration of the hydrochloric acid is 0.5 to 9 M. The method according to claim 1,
Wherein the concentration of the extracting agent is 0.01 M or more per 100 ppm of palladium (Pd). The method according to claim 1,
Wherein the concentration of the extracting agent is 0.01 to 0.02 M per 100 ppm of palladium (Pd). The method according to claim 1,
Wherein said water is diluted twice or less with water. The method according to claim 6,
Wherein the volume ratio (A / O) of the water phase to the organic phase in the stripping step is 1: 1 or more. delete

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