JPH06340932A - Method for selectively dissolving metal - Google Patents

Abstract

PURPOSE:To selectively and efficiently recover only noble metal in the method for allowing a metallic material contg. noble metal and base metal to react in the soln. of a soluble halogen compd. and elemental halogen by using a specified solvent. CONSTITUTION:A metallic material contg. noble metal and base metal is dipped in a soln. of an elemental halogen and soluble halogen compd. to form a metal halide by oxidizing the metal with the elemental halogen. A polyhalogenometal anion complex is then formed with the soluble halogen compd. In this case, a solvent capable of dissolving the polyhalogenometal anion complex and incapable of dissolving base metal is used. Although such a solvent is not specified, a combination of methanol, tetraethyl-ammonium iodide and iodine is exemplified as the solvent, and gold is soluble and copper and Ni are sparingly soluble in the solvent. Further, an oxide film can be formed on the surface of the base metal of the metallic material prior to dissolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for selectively dissolving and recovering a noble metal, and more specifically, to a metal material in which a base metal and a noble metal coexist in a solution in which a soluble halogen compound and a halogen simple substance are dissolved. The present invention relates to a method for selectively dissolving only a noble metal by reacting with, and a method for reducing and recovering the selectively dissolved noble metal.

[0002]

2. Description of the Related Art Melting precious metals is an essential step for extracting and recovering valuable precious metals from various materials containing precious metals (for example, semiconductors and lead frames), and is extremely important industrially. .

As a conventional dissolution method for recovering such valuable precious metals, there has been known a method of dissolving the precious metals in an aqueous solution of an inorganic acid such as hydrochloric acid. However, there is a problem in that a large amount of acidic wastewater is generated and the treatment of this wastewater is very expensive.

Therefore, unlike such a method using an inorganic acid, a method has been proposed in which a noble metal is reacted with a simple substance of halogen and a soluble halogenated salt and dissolved in a solvent composed of at least one of water and a polar organic solvent. (JP-A-59-76834, JP-A-1-242730, JP-A-4-21726, etc.).

[0005]

By the way, in the case of carrying out the above-mentioned method for dissolving a noble metal using a simple substance of halogen and a soluble halogenated salt, further improvement is industrially required.

[0006] One of such major problems is a problem that the contaminant metal contained in the target material is dissolved at the same time as the target noble metal. Simultaneous dissolution of metals other than the target noble metal requires a complicated operation of removing unnecessary metal in the recovery process, which lowers the recovery rate of the target noble metal and increases the burden of recovery equipment and recovery cost. The solution was a big problem.

However, no industrially feasible technique has been proposed so far which can selectively dissolve only the target noble metal from a material in which a plurality of metals coexist.

[0008] In view of the current state of the art, the present inventor has conducted various studies in search of a selective dissolution method of only a target noble metal, which is a very useful method as an actual industrial technology when realized. .

As a result, in the method of dissolving a noble metal as a polyhalogeno metal anion complex (hereinafter abbreviated as "noble metal complex") with the above-mentioned simple substance of halogen and soluble halogen compound, the noble metal is dissolved in a solution prepared by using an appropriate solvent. It has been found that, in the case of melting the base metal, only the target noble metal can be selectively melted without melting the base metal.

Further, by utilizing the difference in properties between the noble metal and the base metal, a method in which only the noble metal can be dissolved as a noble metal complex by the above halogen simple substance and the soluble halogen compound when the target metal material is appropriately pretreated. I found it.

The present invention has been made on the basis of such findings, and an object thereof is to provide a method for dissolving a noble metal which can selectively dissolve only the noble metal from a metal material in which the noble metal and the base metal coexist. To do.

Another object of the present invention is to provide a recovery method capable of selectively and efficiently recovering the target noble metal by utilizing the above-mentioned dissolution method.

Still another object of the present invention is to construct a solution for selectively dissolving only noble metals by a combination of two or more kinds of solvents having a low mutual solubility, and to separate the solvent phase after dissolution. A method capable of facilitating the recovery treatment of the noble metal, in particular, by using a mixed solvent of these mixed solvents of an easily soluble solvent and a hardly soluble solvent of the noble metal complex, it is possible to dissolve the noble metal complex in a high concentration biased to one solvent. It's about providing a way to do it.

[0014]

Means for Solving the Problems and Actions The present inventor has completed the present invention as set forth in each of the claims in order to achieve the above object.

One of the features of the method for selectively dissolving a noble metal according to the present invention is that a metal material in which a noble metal and a base metal coexist is immersed in a solution containing a halogen simple substance and a soluble halogen compound, and the metal by the halogen simple substance is used. When the metal halide is formed by the oxidation reaction to the polyhalogenometal anion complex by the soluble halogen compound and the noble metal complex formed by the above reaction is dissolved in the solution, the base metal is not substantially dissolved. It is configured using a solvent having.

The reaction of dissolving the noble metal by the solution in which the simple substance of halogen and the halogen compound is dissolved appears as a reaction in which the noble metal is converted into a compound in which the noble metal is easily dissolved by contact with the solution. That is, a halogen atom is given from the halogen to the target noble metal to form a metal halide, which is converted into a highly soluble noble metal complex by the action of the soluble halogen compound and the noble metal is dissolved in the solvent. Examples of the soluble halogen compound that can be used in such a reaction include the following compounds (a) and (b). That is, the constituent cations are (a) an alkali metal ion, an alkaline earth metal ion,
Or general formula

[0017]

[Chemical 1]

(Wherein R ₁ , R ₂ R ₃ and R ₄ are hydrogen atoms or hydrocarbon groups having 6 or less carbon atoms), and the anion is a chlorine ion, a bromine ion or an iodine ion. Certain salts are suitable, such as sodium chloride, sodium bromide, potassium iodide, calcium iodide, tetraethylammonium iodide and the like.

(B) A compound obtained by adding hydrogen chloride, hydrogen bromide or hydrogen iodide to an aliphatic or aromatic mono- or polyamine, such as ethylenediamine dihydroiodide. The solution that can be used in the method of the present invention is selectively adopted as a solvent having the property of being able to dissolve a simple substance of halogen and a soluble halogen compound and also capable of dissolving a noble metal complex from the above solvents, and is uniformly used. Although not specified, it is possible to use, for example, a single polar organic solvent, a mixed solvent of an organic solvent and water, for example, alcohols, esters, ketones are suitable, for example, methyl alcohol, methyl acetate. , Methyl ethyl ketone, etc., select the noble metal and base metal contained in the target metal material, the type of halogen simple substance to be dissolved, and the type of soluble halogen compound so that the noble metal is selectively dissolved and the base metal is not dissolved. Therefore, it is not uniformly determined, but selective solubility for the target precious metal and insolubility for the base metal Suitability solvents with a soluble halogen compound, can be obtained by a combination of simple halogen. More specifically, for example, as a solvent for selectively dissolving only a noble metal from a target material in which a noble metal such as gold and palladium and a base metal such as copper and nickel coexist, for example, a single solvent of methanol and tetraiodide are used. A combination of methylammonium and iodine, or a mixed solvent of water and methyl acetate, tetramethylammonium iodide,
Examples thereof include combinations of iodides such as potassium iodide and ammonium iodide, and iodine.

The soluble halogen compound is preferably used in an amount of 0.5 times or more the molar amount of the noble metal to be dissolved. Chlorine, bromine, and iodine are used as the simple substance of halogen, and iodine is particularly preferable, and it is generally used in a molar amount of 0.25 times or more with respect to the noble metal to be dissolved.

Examples of the noble metal that is selectively dissolved by the method of the present invention include gold, silver, and platinum group (platinum, palladium, etc.).

In the above description, the fact that the solution for dissolving the noble metal does not substantially dissolve the base metal is not limited to the case where the concentration of the base metal complex contained in the solution is zero, but it is included in the target metal material. If the dissolution rate of the base metal is as low as about 10% or less, the burden of post-treatment after dissolution can be sufficiently reduced as compared with the conventional method in which the precious metal and the base metal are simultaneously dissolved. The mechanism by which the dissolution liquid does not dissolve the base metal is that the dissolution reaction occurs except when the above-mentioned dissolution reaction by the halogen simple substance and the soluble halide does not occur in the dissolution liquid, but the base metal complex to the solvent constituting this dissolution liquid Any of these may have a low solubility.

In the method of the present invention, it is preferable that at least two kinds of solvents, which are selected from organic solvents and water and constitute a mixed solvent as a mixed solvent, are formed of a combination of solvents having low mutual solubility. It is particularly preferable that the two or more kinds of solvents are composed of a combination of an easily soluble solvent and a poorly soluble solvent for the polyhalogeno noble metal anion complex. The low mutual solubility of the solvents means, for example, that the solvent of each phase can be easily separated by an operation such as separating it into upper and lower parts by allowing it to stand still and switching the flow path while flowing out from the lower part of the tank in which it is stored. It is sufficient if the relationship is such that it can be taken out.

By using a mixed solvent of such a combination (for example, a mixed solvent of ethyl acetate and water), the target metal material can be immersed in the solution in a stirring state (using a stirring blade device or in a turbulent flow state). , The noble metal complex can be dissolved in one solvent phase (ethyl acetate) at a higher concentration than that of the aqueous phase, and since these solvents are easily separated by standing, the noble metal complex is separated after standing. The precious metal is reduced and recovered from the solvent phase that is dissolved in the concentration, and the other aqueous phase is recycled to the next dissolution step. Reduction and downsizing of equipment can be realized.

The selective melting method of the noble metal of the present invention also achieves the object by performing a pretreatment for forming an oxide film on the base metal surface of the target metal material prior to the melting treatment of the target metal material. be able to.

The method of forming such an oxide film on the surface of the metal varies depending on the types of the noble metal and base metal contained in the target metal material, but for example, a method of heating the target metal material to oxidize it, or oxidizing the surface of the noble metal. It is possible to use a method in which a base metal is easily oxidized to form an oxide film without forming a film, for example, a method of contacting with an oxidizing agent such as a peroxo acid to oxidize the base metal.

Then, only the noble metal can be selectively dissolved by subjecting the target metal material, which has been pretreated to form such an oxide film, to the dissolution treatment using the above-mentioned solution, halogen simple substance, and soluble halogen compound. . In this case, since the base metal does not dissolve and react due to the presence of the oxide film, the solvent to be used can be appropriately selected without being restricted by the fact that the base metal complex is not dissolved.

[0028]

EXAMPLES Next, the present invention will be described in detail with reference to Examples.

Example 1 1 mmol of tetraethylammonium iodide and 0.5 mmol of iodine were dissolved in 10 g of methanol to prepare a solution.

This solution was placed in one reaction vessel, and a gold wire, a copper wire, and a nickel wire each having a diameter of 0.2 mm were separately immersed under stirring, and each was heated under reflux at around the boiling point for 30 minutes. When the molten state of each metal wire was measured by weight reduction, the gold wire was 100% melted, but the dissolution rate of the copper wire was 6.2.
%, And the nickel wire dissolution rate was 3.3%.

Example 2 1 mmol of tetraethylammonium iodide and 0.5 mmo of iodine were added to a mixed solvent of 5 g of methyl acetate and 5 g of water.
1 was dissolved to prepare a solution.

This solution was placed in one reaction tank, and a gold wire, a copper wire, and a nickel wire each having a diameter of 0.2 mm were individually immersed under stirring, and each was heated under reflux at around the boiling point for 15 minutes, When the dissolved state of each metal wire was measured, 1500 mg of the gold complex was dissolved in the solution in the reaction tank in which the gold wire was immersed, but copper and nickel were not dissolved in the solution in the reaction tank in which they were immersed. It was undetected. The measurement of the complex is I
This was done by CP emission spectrometry (same in the examples below).

Example 3 1 mmol of potassium iodide and 0.5 mmol of iodine were dissolved in a mixed solvent of 5 g of methyl acetate and 5 g of water to prepare a solution.

Prior to melting, the temperature was set at 2000 ° C., 5
A gold wire, a copper wire, and a nickel wire having a diameter of 0.2 mm that had been subjected to a burning treatment for 2 seconds were prepared.

The above-mentioned dissolved solution was placed in one reaction tank, and the gold wire, copper wire, and nickel wire which had been subjected to the above-mentioned burning treatment were immersed in the solution under stirring, and all were heated under reflux at around the boiling point for 15 minutes. When the dissolution state of the metal wire was measured, 500 mg of the gold complex was dissolved in the solution in the reaction tank in which the gold wire was immersed, but copper and nickel were copper and nickel were the solution in the reaction tank in which they were immersed. Then, it was not dissolved and was not detected.

Example 4 1 mmol of ammonium iodide and 0.5 mmol of iodine were dissolved in a mixed solvent of 5 g of methyl acetate and 5 g of water to prepare a solution.

Prior to melting, the temperature was set to 2000 ° C. and 5 ° C., respectively.
0.1 g of a metal material mixed with 10 parts of palladium, 45 parts of aluminum, and 45 parts of zinc that have been subjected to a burning treatment for 2 seconds
Prepared.

The above burned metal material was immersed in a reaction vessel containing the above solution, heated under reflux at around the boiling point, and the dissolved state was measured. As a result, 1000 mg / kg of palladium complex was dissolved in the solution. However, aluminum and zinc did not dissolve and were not detected.

Example 5 1 mmol of potassium iodide and 0.5 mmol of iodine were dissolved in 10 g of methanol to prepare a solution.

Further, 0.1 g of a metal material was prepared by mixing 10 parts of palladium, 45 parts of aluminum and 45 parts of zinc, which were each subjected to a combustion treatment at 2000 ° C. for 5 seconds prior to melting.

The above burned metallic material was immersed in a reaction vessel containing the above solution, heated under reflux at around the boiling point, and the dissolved state was measured.
Although mg / kg of the palladium complex was dissolved, aluminum and zinc were not dissolved and was not detected.

Example 6 1 mmol of ethylenediamine dihydroiodide and 0.5 mmol of iodine were dissolved in 10 g of methyl acetate to prepare a solution.

Further, 0.1 g of a mixed metal material containing 10 parts of palladium and 90 parts of copper, which had been previously oxidized by immersing in an aqueous solution of potassium peroxosulfate prior to dissolution, was prepared.

When the metal material subjected to the above-mentioned oxidation treatment was dipped in a reaction vessel containing the above-mentioned solution and heated under reflux at around the boiling point and the dissolution state was measured, it was found to be 80 in the solution.
Although 0 mg / kg of palladium complex was dissolved, copper was not dissolved and was not detected.

[0045]

According to the selective dissolution method of the present invention, the operation is simple, and it is possible to selectively dissolve gold, silver, and platinum group coexisting base metals without simultaneous dissolution.
Further, the following effects can be obtained.

Since the metal that is contaminated with the noble metal is selectively dissolved, the separation and purification step can be omitted, and the cost can be reduced.

If a strong acidic substance such as hydrochloric acid is not used, and if the type of organic solvent and the mixing ratio with water are taken into consideration, problems such as flammability can be greatly improved, and safety is excellent.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutomu Sugiura 1791-1 Toki-cho, Midori-ku, Chiba City, Chiba Prefecture (72) Inventor Hidetoshi Kawabuchi 6-10-9 Katsutadai, Yachiyo City, Chiba Prefecture (72) Hiroyuki Nakazawa 21-2 Midoricho, Mobara-shi, Chiba

Claims (6)

[Claims] 1. A metal material, in which a noble metal and a base metal coexist, is immersed in a solution in which a simple substance of halogen and a soluble halogen compound are dissolved to generate a metal halide by an oxidation reaction of the simple substance of halogen to a metal, and then the soluble halogen. In the dissolution method for producing a polyhalogenometal anion complex by a compound, in the above-mentioned solution, a polyhalogenometal anion complex of a noble metal produced in the above reaction is dissolved, but a base metal is characterized by using a solvent that is not substantially dissolved. A method for selectively dissolving a metal. 2. A metal material in which a noble metal and a base metal coexist is immersed in a solution in which a simple substance of halogen and a soluble halogen compound are dissolved, and a metal halide is produced by an oxidation reaction of the simple substance of halogen to a metal, and then the soluble halogen. In the dissolution method for forming a polyhalogeno metal anion complex with a compound, prior to the above-mentioned dissolution, a pretreatment for forming an oxide film on the surface of the base metal of the above-mentioned metal material is performed, and the selective dissolution method for the metal. 3. The solution according to claim 1 or 2, wherein the solution is composed of a polar organic solvent capable of dissolving a simple substance of halogen and a soluble halogen compound, or a mixed solvent of at least two kinds selected from an organic solvent and water. A method for selectively dissolving a metal, which comprises: 4. The metal according to claim 3, wherein at least two kinds of solvents selected from an organic solvent and water and constituting a solution as a mixed solvent are composed of a combination of solvents having low mutual solubility. Selective dissolution method. 5. The selection of a metal according to claim 4, wherein the at least two kinds of solvents constituting the solution as the mixed solvent are a combination of an easily soluble solvent of the polyhalogeno noble metal anion complex and a poorly soluble solvent. Dissolution method. 6. A metal selection method characterized in that the noble metal is recovered by reducing the polyhalogeno noble metal anion complex in a solution in which the noble metal is selectively dissolved by the dissolution method according to any one of claims 1 to 5. Recovery method.