JPS61238927A - Method for recovering palladium - Google Patents

Abstract

PURPOSE:To effectively recover high purity Pd from an aqueous soln. contg. Pd in a short time by bringing the soln. into contact with an extracting solvent contg. aldoxime represented by a specified formula. CONSTITUTION:An aqueous soln. contg. Pd is prepd. by dissolving a substance contg. Pd such as a waste catalyst or scraps in a mineral acid such as hydrochloric acid or aqua regia. The soln. contg. Pd is brought into liq.-liq. contact with an extracting solvent contg. aldoxime represented by the formula (where R is 7-11C alkyl). 2-Ethylhexanal oxime or the like is used as the aldoxime extracting reagent and added to an org. solvent such as paraffin hydrocarbon by 50-1wt%. Pd can be extracted and transferred to the solvent in a high yield. The solvent contg. the extracted Pd is brought into contact with an aqueous soln. of ammonia or a thio compound such as thiourea to obtain an aqueous soln. contg. Pd by back extraction.

Description

[Detailed description of the invention] (Industrial application field) The present invention is a method for recovering palladium by solvent extraction.

In particular, it relates to a method for selectively and efficiently recovering palladium with high purity from waste catalysts, plating waste liquids, various scraps, and anode slimes. Anode slime is produced during the smelting process of ores such as copper, nickel, and zinc, and contains gold, silver, various platinum metal elements (including palladium), selenium, tellurium, etc.

(Prior Art) Palladium is one of the industrially indispensable metals that is widely used in catalysts, electrical/electronic materials, dental materials, etc. Palladium is.

It is one of the rare elements whose concentrate hardly exists, and is mainly obtained as a by-product of copper smelting.

While Japan's demand for palladium ranks second in the world, most of the raw material copper concentrate is imported from abroad. Therefore, it is desired to effectively recover palladium from palladium-containing materials such as waste catalysts and various scraps.

Palladium is recovered from the palladium-containing material by dissolving the palladium-containing material in aqua regia.

This is carried out by a method in which powdered zinc, copper, formic acid, or formalin is applied to this to reduce it.

However, with this method, it is difficult to separate other metals, especially platinum group elements other than palladium, which have similar properties to palladium, such as iridium.

Moreover, since aqua regia is used, there is a drawback that harmful nitrogen oxides are generated.

In response, palladium recovery methods using solvent extraction methods and ion exchange methods have been proposed. In such a method, trace metal ions such as palladium can be relatively easily separated from an aqueous solution. In South Africa and the United Kingdom, precious metal refining plants using such solvent extraction methods and ion exchange methods are being constructed. In both of these plants, extractants are used to extract palladium. Hydroxyoxime and alkyl sulfide are used as the extractant. All of these extractants can selectively extract palladium. Shigashi.

If the extraction rate is very slow and the extraction is performed in a single batch operation, it may take several days to reach equilibrium.

(Problem that the invention attempts to solve) The present invention solves the above-mentioned conventional drawbacks.

The objective is to provide a method for effectively recovering high-purity palladium from palladium-containing materials such as spent catalysts and various scraps.

Another object of the present invention is to provide a method for recovering palladium by solution extraction using an extractant that can selectively extract palladium from the palladium-containing material, rapidly, and in high yield.

(Means for Solving the Problems) The palladium recovery method of the present invention involves bringing an extraction solvent containing an aldoxime represented by the following general formula as an extractant into liquid-liquid contact with a palladium-containing aqueous solution.

and extracting palladium into the solvent.

The above object is thereby achieved: (where R is an alkyl group having 7 to 11 carbon atoms).

In addition to the above recovery method, the palladium recovery method of the present invention further includes back-extracting the palladium-containing extraction solvent with an ammonia aqueous solution or a thio compound aqueous solution,
obtaining an aqueous palladium solution, thereby achieving the above object.

In the method of the present invention, palladium present in the form of a salt such as chloride in an aqueous solution is extracted and recovered. Therefore, when recovering palladium from waste catalysts and various scraps,
A palladium-containing aqueous solution is prepared by dissolving these palladium-containing substances in a mineral acid such as aqua regia. Palladium in aqueous solutions can be present in the form of chlorides, nitrates, sulfates, depending on the type of mineral acid used in preparing the aqueous solution and the method of treatment before extraction. A chloride (hydrochloric acid) solution is preferably used in view of the solubility of palladium and the price of mineral acids. Furthermore, recovery of palladium dissolved in aqua regia containing hydrochloric acid and nitric acid can also be suitably performed.

As an extractant, an aldoxime having the following structural formula is used: (where R is an alkyl group having 7 to 11 carbon atoms).

When this extractant is dissolved in a suitable organic solvent and the palladium-containing aqueous solution is brought into liquid-liquid contact, palladium is extracted into the organic layer. If the number of carbon atoms in the alkyl group of the extractant is 6 or less, the water solubility will be too high and the extractant will migrate to the aqueous phase and be lost. When the number of carbon atoms is 12 or more,
The viscosity of the organic solvent containing the extractant increases, making phase separation between the aqueous phase and the organic phase difficult. For example, the above aldoxime includes one.

There are 2-ethylhexanal oxime, n-octanal oxime, n-decanal oxime, and n-dodecanal oxime. Two or more types of extractants may be used in combination. Such mixtures of two or more types are relatively easy to obtain and often inexpensive. These aldoximes are readily produced in high yields by the reaction of aldehydes with hydroxylamine, for example in ethanol solvents.

Since aldehydes and hydroxylamine can be obtained at low cost as industrial chemicals, aldoximes can be provided at low cost.

When obtaining a mixture of two or more aldoximes, a mixture of two corresponding aldehydes is used. The production of aldoxime is shown by the following formula: (R is an alkyl group having 7 to 11 carbon atoms.) As the organic solvent, a conventional organic solvent that can dissolve the above-mentioned extractant can be used. For example, paraffinic hydrocarbons, naphthenic hydrocarbons, and aromatic hydrocarbons are preferably used. The above-mentioned extractant is generally contained in the organic solvent in a proportion of 100 to 0.5% by weight, preferably 50 to 1% by weight. When performing liquid-liquid extraction, free mineral acid may be included in the aqueous solution containing the palladium salt. For example, when using an aqueous solution of palladium in hydrochloric acid, the concentration of hydrochloric acid is approximately 0.01 to 5. ON is preferred. Although palladium can be extracted satisfactorily even with a highly concentrated mineral acid solution, more mineral acid is used than necessary, which is wasteful and reduces the deterioration of the extractant. When metals other than palladium are mixed in the aqueous solution.

If the mineral acid concentration is too high, these other metals will also be extracted into the organic phase at the same time. In particular, 2 with similar properties to palladium.
When separating valent or tetravalent platinum, the concentration of hydrochloric acid is 0.301-1. It is preferable to turn it ON.

A known method can be used for contacting the aqueous phase and the organic phase. It can be carried out by single-stage batch liquid-liquid contact, but it can also be carried out using a column-type or two-tank multi-stage liquid-liquid contacting apparatus. In this way, high yield and high purity palladium can be recovered in the organic phase.

When aldoxime, which is an extractant, is used for a long period of time, a portion of it is oxidized and turns into aldehyde, which may reduce its extraction ability. This is the LI used for 2wi hydrometallurgical smelting.
The same is true for hydroxyoxime extractants such as X64N (trade name). In such a case, a regeneration method used for hydroxyoxime extractants may be applied. This regeneration method.

For example, it is disclosed in Japanese Patent Application Laid-open No. 54-112377. According to the method, aldoxime, which has been partially converted to aldehyde, is mixed with a concentrated alkaline aqueous solution of hydroxyamine, and excess alkali is neutralized with sulfuric acid or the like. By such a method, it is possible to regenerate aldehyde into aldoxime.

When the palladium-containing organic phase thus obtained is then brought into contact with an aqueous ammonia solution or an aqueous thio compound solution, palladium is back-extracted into the aqueous phase. As the thio compound, thiourea, thiosulfate, thiocyanate, etc. are used. The concentration of the back extractant such as ammonia or thio compound is usually from 0.51 Wot/1 to saturation concentration, preferably from 1 to 5 mol/l. The organic phase after back extraction can be used as feed back to the extraction process. In this way, an aqueous solution containing palladium is obtained.

(Function) According to the method of the present invention, high-purity palladium can be effectively recovered in a short time from an aqueous solution containing palladium by a solution extraction method. Since the extractant used selectively extracts palladium in a predetermined mineral acid concentration range, it is possible to recover palladium selectively and in high yield even from an aqueous solution containing other metals. Normally, when the extraction performance of the extractant is excellent, back extraction is often difficult. However, in the method of the present invention, palladium can be effectively back-extracted using a specific back-extracting agent such as ammonia or a thio compound. Palladium in the back-extracted aqueous solution can be easily obtained as metallic palladium by known methods.

(Experiment example) The present invention will be explained below using experimental examples.

Dahui Charcoal [Extraction of palladium with 2-ethylhexanal oxime] (A) Extraction of palladium: 109.5 pp of palladium
m (Concentration as metal palladium; below.

The same applies to each metal) containing IN hydrochloric acid 0.
031 and 0.031 of a toluene solution of 2-ethylhexanal oxime (R in the structural formula of aldoxime used as an extractant corresponds to 1-ethylpentyl group) of 0.1 n+ol/l were shaken using a mechanical shaker.

When the palladium concentration in the aqueous phase was measured, it was 0.9 ppm after 10 minutes and below O.ippm after 20 minutes. It was found that approximately 20 minutes of shaking resulted in almost complete extraction of palladium.

Next, 1 containing palladium in a proportion of about 1100 pp
Extraction of palladium from aqueous hydrochloric acid solutions with zero concentrations was performed in the same manner as above. The concentrations of hydrochloric acid in the palladium-containing solutions used were different.

0.0IN, 0.03N, 0. IN, 0.2N, 0.3
N, 0.5N, 1. ON, 2. ON, 3. ON and 5
．． It is ON.

The shaking time is 20 minutes. After 20 minutes, the palladium concentration in the aqueous phase was measured. The exact initial concentration of palladium in each palladium-containing solution used and the concentration of palladium contained in the aqueous phase after extraction are shown in Table 1, respectively.

(Blank below) Table 1 (B) Reverse extraction of palladium: The organic phase containing 1104 pp of palladium extracted by the method in section (A) and an equal volume of the reverse extract were shaken for 30 minutes using a mechanical shaker. An aqueous IN ammonium thiocyanate solution was used as the back extraction solution. The concentration of palladium back-extracted into the aqueous phase was measured, and the back-extraction rate was calculated. The results are shown in Table 2.

Next, 2N ammonium thiocyanate was used as the back extraction solution.
Back extraction from the organic phase containing approximately 1100 pp of palladium was carried out using 2N ammonia and 1 mol/R aqueous thiourea solution, respectively. Table 2 shows the exact initial palladium concentration of the organic phase used, the concentration of palladium back extracted into the aqueous phase, and the back extraction rate. It is clear from Table 2 that an aqueous ammonium thiocyanate solution is particularly excellent as a back extraction solution.

Table 2 [Extraction of palladium with n-octanal oxime] According to the method in Experimental Example 1 (A) using n-octanal oxime as an extractant from aqueous hydrochloric acid solutions containing palladium at a ratio of about 1100 pp at six different concentrations. Palladium was extracted. The hydrochloric acid concentrations of the palladium-containing solutions used were 0.0 IN and 0.03 N, respectively.

0, IN, 0.5N, 1. ON and 3. is ON,
The shaking time was 30 minutes. The exact initial concentration of palladium in each palladium-containing solution used and the concentration of palladium contained in the aqueous phase after extraction are shown in Table 3, respectively.

Table 3 [Extraction of palladium with n-decanal oxime] Experimental example using n-decanal oxime as an extractant from aqueous hydrochloric acid solutions containing palladium at a ratio of about 1100 pp at seven different concentrations] According to the method in section (A) Palladium was extracted. The hydrochloric acid concentrations of the palladium-containing solutions used were 0.01N and 0.03N, respectively.

0°IN, 0.5N, 1. ON, 3. ON
and 5. ON, and the shaking time was 30 minutes. The exact initial concentration of palladium in each palladium-containing solution used and the concentration of palladium contained in the aqueous phase after extraction are shown in Table 4, respectively.

Table 4 [Extraction of palladium with n-dodecanal oxime] According to the method in Experimental Example 1 (A) using n-dodecanal oxime as an extractant from aqueous hydrochloric acid solutions containing palladium at a ratio of about 1100 pp at six different concentrations. Palladium was extracted. The hydrochloric acid concentrations of the palladium-containing solutions used were 0.01N and 0.03N, respectively.

0, IN, 0.5N, CON and 5. ON, and the shaking time was 30 minutes. The exact initial concentration of palladium in each palladium-containing solution used and the concentration of palladium contained in the aqueous phase after extraction are shown in Table 5, respectively.

Table 5 [Extraction of divalent and tetravalent platinum] (A) Extraction of divalent platinum: Experimental example 1 (A) from six different concentrations of aqueous hydrochloric acid solutions containing platinum (n) at a ratio of approximately 1100 pp. Platinum (II) was extracted according to the method of . The concentration of hydrochloric acid in each of the platinum (n) containing solutions used was 0.0 IN.

0, IN, 0.5N, 1. ON, 2. ON
and 5. ON, and the shaking time was 30 minutes. The exact initial concentration of platinum (If) in each platinum (II)-containing solution used and the platinum (TI) contained in the aqueous phase after extraction.
The concentrations of each are shown in Table 6.

Table 6 (B) Extraction of tetravalent platinum: Experimental example (A) using tetravalent platinum instead of divalent platinum
Extraction experiments were conducted in the same manner as described in Section 1. However, 0.5N
No extraction experiment was performed for the hydrochloric acid aqueous solution of 2. 3 instead of ON. An extraction experiment was conducted using an aqueous solution of ON in hydrochloric acid. The results are shown in Table 7.

Table 7 It is clear from Tables 6 and 7 that divalent and tetravalent platinum is hardly extracted when the concentration of hydrochloric acid is low. Therefore, when selectively extracting palladium from an aqueous solution containing a mixture of palladium and platinum, it is preferable to lower the mineral acid concentration (in the case of hydrochloric acid, lower than IN).

Daejakudan [Extraction of copper (U)] 1 containing copper (n) at a ratio of approximately 0.01 mol/l
Experimental Example 1 Using O, 1 mol/(l) of 2-ethylhexanal oxime from aqueous hydrochloric acid solutions of seven different concentrations.
Copper (n) was extracted according to the method in section (A). The hydrochloric acid concentration of each copper (n) containing solution used was 0.05N.
, 0. IN, 062N, 0.3N, Q. 4N, 0.
5N.

0.7N, 1. ON, 1.5N, 2. ON, 2°5
N, 3. ON, 4. ON, 5. ON,
6. ON, 7. ON and 8°ON, and the shaking time was 30 minutes. Copper (I) in each copper-containing solution used
The exact initial concentration of I) and the concentration of copper(n) contained in the aqueous phase after extraction are shown in Table 8, respectively.

(Left below) Table 8 [Extraction of nickel] 8 containing nickel at a ratio of approximately 0.01 mol/1
Nickel was extracted from aqueous hydrochloric acid solutions of various concentrations according to the method in Section (A) of Experimental Example 1. The hydrochloric acid concentration of each nickel-containing solution used was 0. IN, 1. ON,
2. ON, 3. ON, 4. ON, 5. O
N, 6. ON and 8. ON, shaking time is 3
The duration was 0 minutes. The exact initial concentration of nickel in each nickel-containing solution used and the concentration of nickel contained in the aqueous phase after extraction are shown in Table 9, respectively.

Table 9 [Extraction of iron (I)] Iron (I) was extracted from hydrochloric acid aqueous solutions of five concentrations containing iron (III) at a ratio of approximately 0.01 mol/It according to the method in Experimental Example 1 (A). III) extraction was performed. The hydrochloric acid concentration of the iron (DI) containing solution used was 0.01N,
0. IN, 1. ON, 2. ON and 5. O
It is N. Contact with the extract was performed by shaking in an incubator for 24 hours. The exact initial concentration of iron (III) in each iron-containing solution used and the concentration of iron (I[I) contained in the aqueous phase after extraction are shown in Table 10, respectively.

Table 10 [Extraction of cobalt (n)] Experimental example 1 (A) from four different concentrations of hydrochloric acid aqueous solutions containing cobalt (II) at a ratio of approximately 0.01 mol/l.
Kobal) (If) was extracted according to the method described in Section 3.

The hydrochloric acid concentration of the aqueous solution containing Kobal) (n) used was 0. IN, 1. ON, 2. ON and 5°ON
The shaking time was 30 minutes. The extraction rate of cobalt from 5°ON hydrochloric acid was 5.2%. 2. Almost no cobalt was extracted from hydrochloric acid below ON.

EXAMPLE 11J Extraction [Extraction of Zinc] The same method as in Experimental Example 9 was used except that an aqueous solution containing zinc was used instead of Kobal) (n). Zinc is 0°IN, 1. Very little was extracted from the hydrochloric acid solution of ON and 2,ON. 5. The extraction rate from ON hydrochloric acid was 0.8%.

Extraction of Cadmium Extraction was carried out in the same manner as in Experimental Example 9 except that an aqueous solution containing cadmium was used instead of cobalt (n).

Cadmium is 0. IN, 1. ON and 2. Very little was extracted from the hydrochloric acid solution of ON. 5. The extraction rate from ON hydrochloric acid was 3.2%.

Skin [Extraction of Magnesium] The same method as in Experimental Example 9 was used except that an aqueous solution containing magnesium was used instead of cobalt (II). Substantially no magnesium was extracted from the aqueous solution at any hydrochloric acid concentration.

Disembowelment dish U [Calcium extraction] The same method as in Experimental Example 9 was carried out except that an aqueous solution containing calcium was used instead of cobalt (n).

Substantially no calcium was extracted from aqueous solutions of any hydrochloric acid concentration.

Osa Masugai [Extraction of aluminum] The same method as in Experimental Example 9 was conducted except that an aqueous solution containing aluminum was used instead of cobalt (n). Aluminum was not substantially extracted from the aqueous solution at any concentration of hydrochloric acid.

Large Stomach Doctor ■ [Extraction of Manganese (II)] The same method as in Experimental Example 9 was used except that an aqueous solution containing manganese (II) was used instead of cobalt (I). Manganese was not substantially extracted from aqueous solutions of any hydrochloric acid concentration.

(Effects of the Invention) According to the method of the present invention, high-purity palladium can be effectively recovered in a short time from an aqueous solution containing palladium by the solution extraction method. The extractant used selectively extracts palladium in a predetermined mineral acid concentration range, so even from aqueous solutions containing other metals, only palladium can be extracted with high purity.

And it is possible to recover with high yield. Extracted palladium can be effectively back-extracted using specific back-extracting agents. By such a method, high-purity palladium can be effectively recovered from palladium-containing materials such as waste catalysts, plating waste liquids, and various scraps.

that's all

Claims (1)

[Claims] 1. A palladium recovery method comprising bringing an aqueous solution containing palladium into liquid-liquid contact with an extraction solvent containing an aldoxime represented by the following general formula as an extractant, and extracting palladium into the solvent. :▲There are mathematical formulas, chemical formulas, tables, etc.▼ (Here, R is an alkyl group with 7 to 11 carbon atoms). 2. A step of bringing an extraction solvent containing an aldoxime represented by the following general formula as an extractant into liquid-liquid contact with a palladium-containing aqueous solution to extract palladium into the solvent, and adding the palladium-containing extraction solvent to an ammonia aqueous solution or A palladium recovery method including the step of back-extracting with an aqueous thio compound solution to obtain an aqueous palladium solution: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (where R is an alkyl group having 7 to 11 carbon atoms). 3. The recovery method according to claim 2, wherein the thio compound is at least one selected from the group consisting of thiourea, thiosulfate, and thiocyanate.