JP3225188B2 - Extractant for palladium extraction and recovery method of palladium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is palladium extraction extractant BACKGROUND OF THE INVENTION, and to a process for recovering palladium, particularly waste such as electric and electronic materials, spent catalyst, anode mud electrolytic copper bath, an anode of a nickel electrolyte bath The present invention relates to a method for selectively recovering palladium from mud or the like with high purity.

[0002]

2. Description of the Related Art Palladium is an extremely important metal in industry and widely used as various catalysts such as electronic / electric materials, dental materials, and catalysts for treating automobile exhaust gas, and is one of rare metals. In recent years, the recycling of pulp and metals by recycling has become an important issue, and the advanced recycling of rare metals, such as palladium, has been strongly desired. There is also an urgent need to establish a technology for efficient recovery and recycling of palladium from material waste.

[0003]

As a technique for selective and efficient separation of trace metals such as noble metals, a solvent extraction method and an ion exchange method have attracted attention from the viewpoint of energy saving. In the solvent extraction method, the target metal is selectively separated from other metals, that is, an extractant that selectively binds to the target metal at a high rate is selected, and the extracted target metal is easily back-extracted. It is very important. Solvent extraction of palladium is industrially practiced in South Africa and the United Kingdom, and o-hydroxym, amino acid derivatives, alkyl sulfides, and the like are used as extractants. However, it is said that there is a need for an extractant that has higher selectivity and can be back-extracted in a short time in order to improve an effective extraction separation technique.

An object of the present invention is to provide an extractant which is highly selective for palladium and can be back-extracted in a short time, and a method for recovering palladium .

[0005]

The present inventors have SUMMARY OF THE INVENTION As a result of intensive studies in order to achieve the above object, they found not that of compounds suitable for use in palladium extractant, and completed the present invention. That is, the bis (dialkyldithiophosphato) alkanes used in the present invention are represented by the following general formula (I):

Embedded image (In the formula, n is an integer of 1 to 6, and R is a linear or branched alkyl group having 1 to 6 carbon atoms.)

In the bis (dialkyldithiophosphato) alkane represented by the general formula (1), the extraction efficiency of palladium is further increased as the carbon chain length of the alkane portion becomes longer. If the total number of carbon atoms is too large, it exhibits surface active properties, which causes a problem that the phase separation of the aqueous phase / organic phase becomes difficult. Accordingly, in the present invention
In the bis (dialkyldithiophosphato) alkanes to be used, R is an alkyl group having 1 to 6, preferably 2 to 5 carbon atoms, and n is desirably an integer of 1 to 6.

[0007] The bis (dialkyldithiophosphato) alkanes used in the present invention include industrially inexpensive lower alcohols, phosphorus pentasulfide (P ₂ S ₅ ), ammonia,
It can be easily produced in high yield using a dihaloalkane. That is, the method for producing bis (dialkyldithiophosphato) alkanes represented by the above general formula (I) used in the present invention comprises a general formula ROH (where R is a straight or branched chain having 1 to 6 carbon atoms). An alcohol represented by a linear alkyl group) and phosphorus pentasulfide (P ₂ S ₅ ),
After reacting at 0-65 ° C for 4-6 hours, the general formula

Embedded image And the reaction product is filtered, if necessary, to remove solids, and the reaction product and ammonia are removed, preferably
After reacting at 0-60 ° C for 1-2 hours, the general formula

Embedded image To form an ammonium salt of a dialkyl dithiophosphate represented by the formula: and, if necessary, purifying the reaction product by, for example, recrystallization from isopropanol, etc., and reacting the reaction product with the general formula Hal (C _n H _2n ) Hal (Where Hal is C
l, Br or I, n is an integer of 1 to 6, and C _n
H _2n is a linear or branched divalent group) in a non-reactive organic solvent, preferably at 50 to 60 ° C. for 2 to 3 hours. purifying the reaction product Te consists recovering.

As the non-reactive organic solvent which can be used in the above-mentioned production method, acetone, methanol,
Examples include ethanol, isopropanol, and a mixture of these alcohols and benzene. As a method for purifying the final product, for example, a method comprising removing a non-reactive organic solvent, then extracting with ether, removing ether to obtain a crude product, and further purifying by a chromatographic method. Can be adopted.

The extractant for extracting palladium of the present invention contains a bis (dialkyldithiophosphato) alkane represented by the above general formula (I) and an organic solvent, and the method for recovering palladium of the present invention. Is to extract palladium ions with an extractant containing a bis (dialkyldithiophosphato) alkane represented by the general formula (I) and an organic solvent, and then back-extract the extracted palladium with a back-extraction solution. It becomes.

In the present invention, the organic solvent used for the extractant includes aliphatic hydrocarbons such as kerosene and heptane, aromatic hydrocarbons such as toluene and xylene, and polar organic solvents such as 1,2-dichloroethane and chloroform. No. Further, as the back-extraction solution, an aqueous solution of a thio compound such as thiourea, a thiosulfate such as ammonium thiosulfate or sodium thiosulfate, a thiocyanate such as ammonium thiocyanate or sodium thiocyanate, or a hydrochloric acid solution containing these is used. , Can be favorably back-extracted. In this way, pure palladium can be recovered.

In the present invention, palladium present in the form of chloride, nitrate, sulfate and perchlorate in an aqueous solution is extracted and recovered. Therefore, palladium is a waste catalyst,
In order to recover palladium from various wastes, the palladium-containing waste is treated with aqua regia to prepare an aqueous solution containing palladium. A chloride solution is preferably used because of the solubility of palladium. The recovery of palladium dissolved in aqua regia is also preferably performed.

[0012]

EXAMPLES The present invention will be described below in more detail with reference to examples. Example 1 0.5 mol of ethyl alcohol and phosphorus pentasulfide (P ₂ S ₅ )
0.125 mol was reacted at 60 ° C. for 5 hours to produce diethyl dithiophosphate, and the reaction product was filtered to remove solids. 0.2 mol of ammonia was added to the filtrate containing the reaction product and reacted at 60 ° C. for 1.5 hours to produce an ammonium salt of diethyl dithiophosphate, and the reaction product was purified. The reaction product and dibromomethane (0.27 mol) were dissolved in 100 ml of acetone at 60 ° C.
For 2 hours, and the reaction product was purified to obtain bis (diethylthiophosphato) methane. The yield and physical properties of the product were as shown in Table 1.

Examples 2 to 4 In place of dibromomethane used in Example 1, dibromoethane, dibromopropane or dibromobutane was used to obtain the target compound in the same manner as in Example 1. The yields and physical properties of the products were as shown in Table 1. Examples 5 to 8 In the same manner as in Examples 1 to 4 except that isobutyl alcohol was used in place of ethyl alcohol used in Examples 1 to 4, the target compounds were obtained. The yields and physical properties of the products were as shown in Table 1.

[0014]

R and n in the table represent R in the general formula (I).
And n, R _f is the transfer rate in thin-layer chromatography, and K _DR is the partition ratio of the compound in 1,2-dichloroethane to an aqueous solution. In the following description, the compounds obtained in Examples 1 to 8 are described as Compounds 1 to 8, respectively.

Example 9 Extraction of Noble Metal Ion with Compounds 1 to 8 Palladium ion (Pd²⁺), Silver
ON (Ag⁺), Gold ions (Au³⁺) Or platinum ion
(Au⁴⁺) Is 1.0 × 10^-FourContains M (mol / l), inorganic
Sodium perchlorate, sodium chloride as salt or inorganic acid
Solution containing 0.1M sodium chloride, sodium nitrate, or hydrochloric acid
And 2.5 × 10^-3
And 10 ml of a 1,2-dichloroethane solution containing
Shake for 1 hour in a canister shaker to extract precious metals
Was measured, and the extraction rate (%) was determined. Table 2 shows the results.
To Table 3 below. It should be noted that Cu²⁺, Pb²⁺, N
i ²⁺, Zn²⁺, Fe³⁺, Co²⁺Extraction rate measured for
Was 0%, and was not extracted at all.

[0017]

[0018]

Example 10 Effect of hydrochloric acid concentration on palladium extraction 10 ml of hydrochloric acid solution containing 10.6 ppm of palladium
And 10 ml of a 1,2-dichloroethane solution containing 2.5 × 10 ⁻³ M of bis (diethyldithiophosphato) butane (compound 4) or bis (diisobutyldithiophosphato) butane (compound 8) using a mechanical shaker. 1
The amount of palladium extracted was measured by shaking over time, and the extraction rate (%) was determined. The hydrochloric acid concentrations of the used hydrochloric acid solutions were 0.1N, 0.5N, 1.0N, 1.5N, and 2.N respectively.
0N and 3.0N. Table 4 shows the results. In addition,
When the shaking time was 18 hours, the extraction rate was almost 100% at any hydrochloric acid concentration.

[0020]

Example 11 Back extraction of palladium Extracted with the hydrochloric acid concentration of 0.1 N by the method of Example 10.
The organic phase containing 2 ppm of palladium was back-extracted with a 0.5N hydrochloric acid solution containing the same amount of 0.5% thiourea as the organic phase. Table 5 shows the back extraction ratio calculated from the extracted palladium concentration.

[0022]

Example 12 Half-extraction time in palladium extraction with bis (diisobutyldithiophosphato) butane A solution containing 26.6 ppm of palladium, 1.0 M of sodium chloride or sodium nitrate, and bis (diisobutyldithiophosphato) 1.0 × 10 ^-3 butane
The M-containing 1,2-dichloroethane solution was shaken with a mechanical shaker to measure the amount of extraction, and the time required for 50% extraction was determined. This value was 3.7 hours when sodium chloride was used, and 0.75 hours when sodium nitrate was used.

Example 13 Comparison of Addition Efficiency of Palladium with Bis (diisobutyldithiophosphato) butane A 1.0 M hydrochloric acid solution containing 10.6 ppm of palladium was added to 1.0 × 10 ⁻³ M bis (diisobutyldithiophosphato). Shake with a solution of butane in 1,2-dichloroethane,
The amount of palladium extracted from bis (diisobutyldithiophosphato) butane 18 hours after sufficient extraction equilibrium was reached,
From this, the addition efficiency of palladium to this extractant was determined to be 95.1%.

[0025]

The novel bis (dialkyldithiophosphato) alkanes of the present invention are suitable for extracting palladium, and can selectively, efficiently and effectively convert palladium from an aqueous solution containing palladium by a solution extraction method. It can be extracted and recovered in high purity and high yield by rapid back extraction. By such a recovery method, it is possible to efficiently recover the spent catalyst and palladium in various scraps.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Patent Publication No. 42-4454 (JP, B1) Japanese Patent Publication No. 37-4873 (JP, B1) Japanese Patent Publication No. 38-6197 (JP, B1) US Patent No. 3014058 (US U.S. Pat. No. 2,288,628 (US, A) U.S. Pat. No. 2,873,228 (US, A) Chemical Abstracts, Vol. 74, no. 9 (1971) Abstract No. 41810k Chemical Abstracts, Vol. 54, No. 19 (1960) Abstract No. 19458h (58) Fields investigated (Int. Cl. ⁷ , DB name) C07F 9/165 B01D 11/04 C01G 55/00 CA (STN) CAOLD (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A compound of the general formula (I) Wherein n is an integer of 1 to 6, R is a linear or branched alkyl group having 1 to 6 carbon atoms, and bis (dialkyldithiophosphato) alkanes represented by the formula: An extractant for palladium extraction, comprising a solvent. 2. A palladium ion represented by the general formula (I): ## STR2 ## Wherein n is an integer of 1 to 6, R is a linear or branched alkyl group having 1 to 6 carbon atoms, and bis (dialkyldithiophosphato) alkanes represented by the formula: A method for recovering palladium, comprising extracting with an extractant containing a solvent and back-extracting the extracted palladium with a back-extraction solution.