WO1994025633A1

WO1994025633A1 - Method of dissolving and recovering metal

Info

Publication number: WO1994025633A1
Application number: PCT/JP1994/000698
Authority: WO
Inventors: Yukimichi Nakao; Tsutomu Sugiura; Hidetoshi Kawabuchi; Hiroyuki Nakazawa
Original assignee: Japan As Represented By Director General Of Agency Of Industrial Science And Technology; Nihon Tennen Gas Kogyo Co., Ltd.
Priority date: 1993-04-27
Filing date: 1994-04-26
Publication date: 1994-11-10

Abstract

A method of dissolving and, if necessary, further recovering noble metals efficiently from industrial raw materials including gold plated materials such as waste electronic parts, platinum catalysts used in the petrochemical industry, and waste ornaments. The conventional dissolving methods using aqua regia, an alkali cyanide solution and so forth are dangerous and necessitate complicated procedures for separating dissolved matters. The invention method comprises dissolving a simple substance of halogen and a soluble halogen compound in a mixture of two solvents that are selected from the group consisting of organic solvents and water and are lowly soluble in each other, immersing raw noble metal materials in the resulting solution to dissolve them in the form of a complex, leaving the solution at rest to cause phase separation, reducing the noble metal complex dissolved in the solvent phase in a high concentration, and recovering the reduced noble metal.

Description

Technical field Metal dissolution method and recovery method.

The present invention relates to a method for dissolving a precious metal and, if necessary, recovering the precious metal. The present invention relates to a method for industrially producing a gold-plated material such as a waste electronic component, a platinum-based catalyst used in a petrochemical industry, a waste jewelry, etc. As a noble metal raw material, a noble metal was reacted with a simple halogen in the presence of a soluble halogen compound in a mixed solution of two or more solvents to dissolve it, and further, the desired noble metal was distributed to an aqueous phase or an organic solvent phase. It relates to a method for efficiently recovering precious metals in a state.

The present invention also relates to a method for selectively dissolving and recovering a noble metal. Specifically, when the above-mentioned noble metal raw material contains a base metal and a noble metal, a single solvent in which a soluble compound and a simple halogen are dissolved is used. By dissolving the noble metal by reacting it with a simple halogen in the presence of a soluble halogen compound and dissolving it in a dissolving solution consisting of or a mixture of two or more solvents, the base metal is not substantially dissolved or the solubility of the base metal is reduced. The present invention relates to a method for selectively dissolving a noble metal in a sufficiently low state, and a method for reducing and recovering the selectively dissolved noble metal. Background art

Dissolution of precious metals is an indispensable process for extracting and recovering valuable precious metals from various materials containing precious metals (for example, waste industrial materials such as semiconductors and lead frames). It is regarded as industrially important as a technology for recovering precious metals useful in, for example, platinum group such as Au, Ag, Pt, Pd, and Ru for effective use of resources.

Conventionally known methods for dissolving precious metals required to recover this valuable precious metal include (1) dissolving the precious metals in an aqueous solution of an inorganic acid such as aqua regia or hydrochloric acid, and (2) alkali cyanide. Dissolution in solution, or (3) Iodine and iodine A method of dissolving with a mixed aqueous solution containing a compound (Japanese Patent Application Laid-Open No. 59-76834, Japanese Patent Application Laid-Open No. H11-242730) is known. ) A method of contacting a halogen alone with a soluble halide salt and a solvent composed of water and a polar solvent (Japanese Patent Application Laid-Open No. 4-121726 (corresponding US Pat. No. 5,139,752)), etc. Proposed.

However, the conventional techniques described above have drawbacks for industrially implementing this. 'For example, in the method for dissolving precious metals using aqua regia or the like described in (1) above, the solution used is strongly acidic and dangerous, and even the contaminated base metal is dissolved, and the precious metal and base metal are separated in the recovery process. There is a disadvantage that the operation is complicated.

The method (2) of dissolving with an alkali cyanide solution is also highly dangerous, and may dissolve even a base metal, and is expensive and economical for wastewater treatment of a spent alkali cyanide solution. L ,.

The method (3) using a mixed aqueous solution of iodine and iodide, or the method (4) using a solution consisting of a simple substance of a halogen, a halide salt, water and a polar organic solvent, has a limit in dissolving ability to a noble metal. Yes, and because it is necessary to select a polar solvent that sufficiently dissolves the halide salt to be used, the type and amount of the halide salt that can be used are restricted, and the amount of solvent used is large, and oxidizing agents and reduction Due to the large amount of drug used, there are still many issues to be solved on an industrial scale.

In view of the above-mentioned current state of the art, the present inventor has realized a process that is highly safe, can use a small amount of chemicals and the like, can realize an inexpensive process, and is suitable for an industrial-scale process. We have done diligent research on the law.

In the course of that research, a method of treating a target noble metal with a metal halide using a halogen alone or a halide in a polar solvent proposed in Japanese Patent Application Laid-Open No. 4-21726, etc. This is an excellent method based on the reaction of dissolving this in a polar solvent as a polyhalogeno metal anion complex with a halogenated salt. All of which have the property of sufficiently dissolving the “noble metal complex”), and the types of halide salts that can be used It was noted that the amount of solvent used was limited, and the amount of solvent to be used had to be increased, resulting in the problem of using a large amount of chemicals such as a reducing agent.

That is, in a treatment method using a simple substance of halogen and a halide salt, if the above-mentioned restrictions on the solvent to be used can be eliminated, various problems can be solved at once, and it is extremely effective for implementation on an industrial scale.

The present inventor considers this point of view as a first point of interest. In a method of dissolving a noble metal as a noble metal complex using a simple halogen and a halide salt, two types having low mutual solubility, which were not expected at all from the prior art. By using a combination of the above-mentioned solvents, a method for effectively eliminating the above-mentioned restrictions has been found, and the present invention has been completed.

That is, a first object of the present invention made based on the first point of interest is to use the above-mentioned halogen unit and halide salt by using a mixed solution of two or more solvents having a low solubility in each other. In addition to dissolving the noble metal complex, this dissolving treatment allows the solvent phase in which the noble metal complex is dissolved at a relatively high concentration, preferably one solvent phase containing the noble metal complex at a high concentration, to be easily separated from the other solvent phases. It is an object of the present invention to provide a method that enables separation and allows subsequent treatment such as recovery of precious metal to be performed easily and efficiently.

Another object of the present invention in which a mixed solution of two or more solvents having a low solubility in each other is used is to stir a mixed solution of two or more solvents having a low solubility in each other. It is an object of the present invention to provide a method which can reduce restrictions on the solubility of a halogen or a halogen compound which acts on dissolution of a noble metal in a solvent when used in a mixed state as described below.

Further, another object of the present invention using a mixed solution comprising two or more solvents having a low solubility in each other is to use a combination of a hardly soluble solvent and a readily soluble solvent of a noble metal complex, By dissolving the compound at a high concentration so as to be unevenly distributed in a readily soluble solvent, thereby providing a method that can perform the above-mentioned processes such as recovery more efficiently.

A book that uses a mixture of two or more solvents that have a low solubility Another object of the present invention is not only to facilitate the dissolution and recovery of the target noble metal, but also to facilitate the regeneration of the halogen alone and the repeated use of the halogen compound and the organic solvent used in this method. Wastewater treatment can be drastically reduced or substantially omitted, and wastewater treatment equipment can be eliminated or downsized, and the cost can be reduced by drastically reducing the amount of chemicals used. It is intended to provide a method that can effectively realize the implementation in the field.

In addition, in the course of the research conducted by the present inventor to improve the efficiency of dissolving precious metals using the above-described halogen alone and a soluble halide salt, and furthermore, to improve the efficiency of industrial recovery, Apart from using a mixture of two or more solvents with low mutual solubility (dissolution solution), contaminated metals (metals other than precious metals) that may be included in the target material (waste precious metal industrial materials, etc.) Can be dissolved simultaneously with the target precious metal, so that the target precious metal can be selectively dissolved and recovered, and in some cases, from the viewpoint of recycling valuable contaminant metals that coexist with the precious metal. It was found to be beneficial. In other words, if the second point of interest of the present invention, which enables selective dissolution of the target noble metal without substantially dissolving such contaminating metals, can be realized, the recovery by simultaneous dissolution of metals other than the target noble metal This eliminates or reduces the complicated operation of removing unnecessary metals from precious metals, reduces the recovery rate of the target precious metals, and reduces the burden on recovery equipment and recovery costs. In addition to bleaching, contamination metals can be reduced. This is because the possibility of reusing valuable contaminant metals can be advantageously achieved by enabling the solids to be recovered separately from the precious metals.

However, an industrially feasible technology that can selectively dissolve only the target noble metal from a material in which multiple metals coexist has not yet been proposed. The present inventor has conducted various studies in search of a method for selectively dissolving only the target noble metal described above.

~ O

As a result, in the above-described method of dissolving a noble metal as a polyhalogenometal anion complex (noble metal complex) with a simple halogen and a soluble halogen compound, when the noble metal is dissolved in a dissolving solution prepared with an appropriate solvent, A phenomenon that only the target precious metal can be selectively dissolved without dissolving the base metal. did.

In addition, by utilizing the difference in the properties of noble metals and base metals, if the target metal raw material is appropriately pretreated, only the noble metal can be dissolved as a noble metal complex by the above-mentioned simple substance and soluble halogen compound. Found a way.

The method for selectively dissolving a noble metal according to the present invention is based on such knowledge, and its purpose is to dissolve a noble metal capable of selectively dissolving only a noble metal from a metal raw material in which a noble metal and a base metal coexist. It is to provide a dissolution method.

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

Still another object of the present invention is to provide a solution for selectively dissolving only the noble metal according to the first object, comprising a combination of two or more solvents having a low mutual solubility. A method in which the recovery of the noble metal can be facilitated by separating the solvent phase after dissolution, and in particular, by using a mixed solvent of a noble metal complex and a solvent that is sparingly soluble in the noble metal complex, It is an object of the present invention to provide a method capable of dissolving a noble metal complex at a high concentration. DISCLOSURE OF THE INVENTION ''

The present inventor has accomplished the present invention described in each claim of the above claims in order to achieve the above object.

One of the features of the method for dissolving a noble metal using a mixture of two or more solvents having low mutual solubility to achieve the above-described first object of the present invention is that at least two kinds of solvents selected from an organic solvent and water are used. At least one solvent constituting the mixture dissolves a simple halogen, and at least one other solvent constituting the mixture or at least one other solvent comprises a soluble halogen compound. At least one solvent that dissolves and forms a mixture of parentheses is a mixture comprising a combination of solvents that dissolve the polyhalogeno noble metal anion complex. The soluble halogen compound is dissolved, and the noble metal raw material is immersed while stirring the mixture. By this operation, the target precious metal When a halogen atom is given from the halogen, a metal halide is generated, and this is converted into a highly soluble polyhalogeno metal anion complex by the action of a soluble haeogen compound, and the solvent phase of the mixed solution, for example, an aqueous phase And dissolves in organic solvent phase.

Another feature of the present invention that achieves the first object is that following the step of dissolving the noble metal as a complex, the method of dissolving the noble metal as a complex utilizing the property that the mutual solubility of solvents is low. After the mixture is allowed to stand and each solvent phase is separated, a process is carried out in which the noble metal complex dissolved in any of the solvent phases at a high concentration is reduced and the noble metal is efficiently recovered.

The reason for adopting such a structure in the method for recovering a noble metal using the above-mentioned mixed solution of the present invention is that the noble metal complex (polyhalogenometal anion complex) generated by the reaction is biased to any phase of the mixed solution. If they are present, the treatment efficiency can be greatly improved by performing the subsequent process, reduction precipitation only on the phase in which the high concentration is dissolved. Further, by using a mixture of solvents having different properties, there is also obtained an advantage that a solvent having a different solubility of the simple halogen and the soluble halide required for dissolving the noble metal can be appropriately selected and used. The difference in solubility of the noble metal complex in each solvent of the mixed solution, and the magnitude of the difference are not necessarily essential in the present invention. This is because, for example, the phase in which the concentration is relatively low is circulated to the dissolution step after appropriate treatment and used for the next dissolution step, so that the precious metal recovery rate as a whole is not reduced. This is because the advantages of Ming can be effectively used.

In the above description, "the mutual solubility is low" of each solvent forming the mixed solution means that when the mixed solution is allowed to stand, it is easily separated into upper and lower phases and each phase is separated as a solvent. For example, the solvent of each phase can be easily removed separately by, for example, separating the liquid from the upper and lower parts by standing still and switching the flow path while flowing the liquid from the lower part of the storage tank. The solvent of the phase in which the noble metal complex is dissolved at a high concentration as described above is collected independently for the purpose of improving the subsequent treatment, etc., preferably within a few minutes or several tens of minutes. It is enough if it can be separated as much as possible o At least two types of solvents selected from organic solvents and water are selected as a combination of water and an organic solvent or a combination of organic solvents.From the viewpoint of running costs, for example, water and water It is preferable to use a combination of organic solvents having low solubility in water.

Examples of the organic solvent constituting the mixed solution of the present invention include liquid hydrocarbons, esters, ketones, nitriles, and halogenated hydrocarbons. For example, methyl acetate, ethyl acetate, Methyl ethyl ketone is particularly suitable.

The mixing ratio of the solvents having low mutual solubility is not uniformly determined by the solubility of the solvent with respect to a simple halogen, but is generally 1: 9 to 9: 1, preferably 2: 8 to 8: 2, and furthermore, Preferably, it can be used in the range of 4: 6 to 6: 4.

In the present invention, the mixed solution is used in combination with a solvent having low mutual solubility as described above. It is necessary to use a mixture. The mixing method is not particularly limited, but as a general means on an industrial scale, a stirring blade device can be used.

Further, in the present invention using the above mixed solution, at least two kinds of solvents forming the mixed solution are a readily soluble solvent in which the noble metal complex is dissolved at a high concentration, a low solubility of the noble metal complex, and a simple halogen or a soluble halogen compound. It is particularly preferable to use a readily soluble solvent in combination.

By using such a combination of solvents, the noble metal can be dissolved in one solvent at a high concentration and not dissolved in the other solvent as much as possible. If only the phase in which the noble metal or the like is dissolved at a high concentration is taken out, the subsequent recovery operation can be performed with higher efficiency. Since the phase in which the noble metal complex is dissolved at a low concentration contains a high concentration of the unreacted component of a simple halogen or a soluble halogen compound, it can be recycled to the dissolution step and used for the next dissolution step as described above. .

In the case of using a solvent in which the solubility of the noble metal complex is different, it is desirable that there is a difference as large as possible between the solubility of the two noble metal complexes, and the degree is not particularly limited. Is more than 3 Z 7 times, preferably 2/8 In many cases, it is preferable that the ratio be twice or more.

One of the features of the method for selectively dissolving a noble metal that achieves the second object of the present invention is that a metal material in which a noble metal and a base metal coexist is immersed in a solution in which a simple halogen and a soluble halogen compound are dissolved. Then, when the halogen is generated by the oxidation reaction of the metal with the simple halogen and the polyhalogenometal anion complex is formed by the soluble halogen compound, the noble metal complex generated by the above reaction is dissolved in the solution. However, the base metal is constituted by using a solvent having a property of substantially not dissolving. Examples of the noble metal selectively dissolved by the selective melting method include gold, silver, and platinum group metals (platinum, palladium, etc.). In the above description, the term “base metal” is a generic term for metals other than noble metals, and typically includes metals such as iron, nickel, cobalt, and copper, and alloys thereof.

The dissolving solution which can be used in the selective dissolving method of the present invention is a solvent having a property capable of dissolving a simple halogen and a soluble haegen compound and dissolving a noble metal complex from the above solvents. Although it is selectively adopted and is not uniformly determined, it is possible to use, for example, a single polar organic solvent, or a mixture of an organic solvent and water, such as alcohols and liquid hydrocarbons. , Esters, ketones, and halogenated hydrocarbons are suitable. For example, among methyl alcohol, methyl acetate, ethyl acetate, methyl ethyl ketone, etc., selectively dissolve noble metals and do not dissolve base metals. Uniform depending on the type of noble metal and base metal contained in the target metal material, the type of dissolved halogen alone, and the type of soluble halogen compound Without being determined, but can be for purposes noble suitability solvent with insoluble against the selective solubility and base metal, a soluble halogen compounds, may in the combination of simple halogen. More specifically, for example, as a solvent for selectively dissolving only 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 Examples include a combination of ethylammonium and iodine, or a mixed solvent of water and methyl nitrate, and a combination of iodide and iodine such as tetraethylammonium iodide, potassium iodide, and ammonium iodide. be able to. In the above description, the solution in which the noble metal is dissolved does not substantially dissolve the base metal, not to mention that the concentration of the base metal complex contained in the solution is zero, but the base metal contained in the target metal raw material is not limited to this. Includes cases where the dissolution rate is as low as 10% or less. With such a low concentration, the burden of post-treatment after dissolution can be sufficiently reduced as compared with the conventional method in which a noble metal and a base metal are simultaneously dissolved. When the dissolution solution does not dissolve the base metal, the mechanism is that the dissolution reaction does not occur except for the above-mentioned dissolution reaction due to hachigen alone or soluble haematogenide in the dissolution solution. It may be any case where the solubility of the base metal complex in the solvent used is low.

In the selective dissolution method of the present invention, a mixed solution of two or more selected from water and an organic solvent having a low mutual solubility as described above may be used as the dissolution solution. In particular, it is preferable that two or more kinds of solvents are composed of a combination of a readily soluble solvent and a slightly soluble solvent of the polyhalogeno noble metal anion complex for the same reason as described above.

By using a mixed solvent of such a combination (for example, a mixed solvent of ethyl ethyl and water), the target metal raw material can be immersed in a solution in a stirring state (using a stirring blade device or in a turbulent state). The noble metal complex can be dissolved in one of the solvent phases (ethyl acetate) at a higher concentration than the aqueous phase, and these solvents are easily separated by standing. The precious metal is reduced and recovered from the solvent phase after being dissolved to a concentration, and the other aqueous phase is recycled to the next dissolution process, thereby recovering a high rate of the precious metal and reducing the volume of the liquid during the reduction recovery. Phenomenon and, consequently, reduction of reducing agent and downsizing of equipment can be realized.

The method for selectively dissolving a noble metal according to the present invention achieves the object by performing a pretreatment for forming an oxide film on the surface of a base metal of the target metal material prior to the dissolution treatment of the target metal material. Can be.

The method of forming such an oxide film on the metal surface varies depending on the types of the noble metal and the base metal contained in the target metal raw material, but for example, a method of heating and oxidizing the target metal raw material can be used. When this oxide film is formed, noble metal raw materials Is preferably performed by shredding.

By subjecting the target metal raw material that has been subjected to the pretreatment for forming such an oxide film to a dissolution treatment using the above-described solution, a simple halogen, or a soluble halogen compound, only the noble metal can be selectively dissolved. In this case, since the base metal does not undergo a dissolution reaction due to the presence of the oxide film, an appropriate solvent can be selected as the solvent to be used without being restricted to dissolving the base metal complex.

In the present invention, the simple halogen used for dissolving the noble metal includes chlorine (C 1), bromine (Br), and iodine (I), and iodine is particularly preferably used. The concentration of the halogen simple substance is preferably at least 0.25 times the mole of the target noble metal, and more preferably at least 0.5 times the mole in order to promote the dissolution reaction.

Examples of the soluble halogen compound include the following, that is, those in which the constituent cation is any of the following (a) to (c).

(a) Alkali metal ion, alkaline earth metal ion, or the following general formula

^R 2

R N -R

R

(Wherein, R ₂ , R ₃ and R ₄ are a hydrogen atom or a hydrocarbon group having 6 or less carbon atoms) and a salt wherein the anion is a chloride ion, a bromine ion or an iodine ion Suitable are, for example, tetraethylammonium iodide, lithium iodide, and ammonium iodide.

(b) Compounds obtained by adding hydrogen chloride, hydrogen bromide, hydrogen iodide, and the like to aliphatic and aromatic mono- and polyamines, for example, ethylenediamine dihydroaideide.

(c) Compounds obtained by adding a hydrogen halide to an aminopolycarboxylic acid, such as glycine hydroaodiide. The amount of the soluble halogen compound is preferably at least 0.5 times, preferably at least equimolar, the amount of the target noble metal to be dissolved in order to promote the dissolution reaction and to improve the stability of the resulting complex.

The time required for dissolving the noble metal varies depending on the target noble metal, the soluble halogen compound to be used, the type and concentration of the halogen alone, and the type of the mixture of water and the organic solvent. The melting point is lower than the boiling point of the metal. The end point of the noble metal dissolution can be easily confirmed by the invisible charged noble metal.

According to the method using a mixed solution of two or more solvents of the present invention or a selective dissolution method, a noble metal is dissolved in an aqueous phase or an organic solvent phase, and a complex of the noble metal is further reduced. It can be recovered by ordinary methods such as drying and drying. The reducing agent used in the reduction may be any as long as it does not inhibit the reaction of the present invention by reducing the target noble metal, and examples thereof include sodium borohydride, hydrazine and its salts, sulfurous acid and its salts, and sodium hydrogen sulfite. it can. The reduction reaction can be performed, for example, on a phase in which the target noble metal is dissolved, after separating the aqueous phase or the organic solvent phase, for example. The treatment temperature is selected below the boiling point of the target phase, generally in the range of room temperature to 40 ° C and 50 ° C. The end point of the reduction reaction may be performed, for example, until no new precipitation phenomenon is observed while the reducing agent is being added.

The solvent after completion of the above reduction reaction and recovery of the target noble metal can be regenerated and used as a solution for the next dissolution step. For example, after the noble metal is recovered and separated, the aqueous phase or the organic solvent phase is oxidized, and then both phases are mixed to prepare a predetermined solution composition, which can be reused as a solution (the above-mentioned mixture). When the aqueous phase and the organic solvent phase are mixed again to form a regenerated mixed solution, it is necessary to adjust the oxidation ratio of the halogen compound so that the concentration of the halogen alone becomes a predetermined concentration. The oxidizing agent used in this oxidation reaction may be any oxidizing agent that has an oxidizing ability with respect to the halogen compound used within a range that does not inhibit the reaction of the present invention. Examples include sodium chlorite, hydrogen peroxide, and sodium nitrite.

The method of the present invention involves the use of expensive noble metals such as gold, silver, and platinum groups (platinum, palladium, ruthenium). Dissolution of tin, rhodium, etc.) Used effectively for recovery.

The present invention relates to a gold-plated material such as a waste industrial material in which a noble metal is added to a waste electronic component, a base metal or an alloy thereof, a platinum-based catalyst used in the petrochemical industry, a waste jewelry, and the like. It can be used for recovery, and when precious metals are exposed on the surface, these industrial raw materials can be used without shredding or shredded to an appropriate size suitable for immersion treatment. If the noble metal is not exposed on the surface of the raw material, the noble metal may be exposed on the surface by shredding or grinding. It can also be applied to crushing ore containing precious metals to extract precious metals. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram schematically showing an outline of the configuration of an apparatus used to carry out the method of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

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

Examples 1 to 7 shown below are examples corresponding to the first object of the present invention using a mixture of two or more types of water and organic solvents having low mutual solubility.

Example 1

FIG. 1 schematically shows an outline of an apparatus in which the following examples were performed. First, two kinds of predetermined solvents were charged into a reaction tank 1 using the apparatus shown in FIG. A simple noble metal material and a soluble halogen compound are added, and a predetermined noble metal material is added to these mixed solvents while being stirred by the stirring blade device 4 to be dissolved.

When it is confirmed that the dissolution of the noble metal material has been completed visually, the stirring blade device 4 is stopped and allowed to stand, and the two kinds of solvents are separated into upper and lower two phases.

After that, the on-off valves 5 and 6 are opened, and the separated phase (for example, a phase containing a high concentration of halogen alone and little dissolution of noble metal) in the lower part of the reaction tank 1 is transferred to the solution storage tank 2. When the transfer of the lower phase is completed, close the on-off valves 5 and 6 above. Next, the on-off valves 5 and 7 are opened, and the separated phase (for example, halogen (A phase in which the concentration of precious metals is low and the precious metal is dissolved in a high concentration) is transferred to the reduction / regeneration tank 3.

After the transfer of the liquid is completed, a reducing agent is added to the reducing and regenerating tank 3, and the desired noble metal is deposited under stirring by the stirring blade device 10, and the valve 8 is opened to let the precipitated noble metal flow downward to be drawn. Recover by filtration without filtration. Valve 8 closes as soon as the precious metal precipitates out.

After the dissolution and recovery processing of the noble metal is completed as described above, the concentration of the simple halogen is adjusted by performing a predetermined treatment such as oxidizing the solution in the solution storage tank 2 and the reduction and regeneration tank 3. These liquids are returned to the reaction tank 1 via 9 to prepare for the next dissolving operation.

The following noble metal was dissolved and recovered using the apparatus shown in Fig. 1.

(1-1) Dissolution process

1 mmol of tetraethylammonium iodide and 0.5 mmol of iodine were dissolved in 5 g of ethyl acetate and 5 g of water. Tetraethylammonium iodide was dissolved in the aqueous phase at a high concentration, and iodine was dissolved in the ethyl acetate at a high concentration.

This mixed solution is placed in a reaction tank, and sufficiently stirred with a stirring blade device.

A 2 mm gold wire (0.0421 g) was heated at reflux near the boiling point for 15 minutes. After the heating was completed, the mixture was allowed to stand for 1 minute.After the solvent was separated into two phases, each phase was separated and taken out. The concentration of the gold complex dissolved in each of the solvents was measured.

334 Omg / kg and 125 Omg / kg of gold were dissolved in the aqueous phase.

The measurement of the gold complex was carried out by means of an ICP emission spectrometry (the same applies to the following examples).

(1-1-2) Collection process

Next, sodium borohydride was added to each of the ethyl acetate phase and the aqueous phase in which the gold separated as above was dissolved as a complex to reduce gold, and the deposited gold was collected by filtration. .

When the concentration of the gold complex in the ethyl acetate phase and the aqueous phase after gold filtration was measured, no residual gold was detected, and the recovery was 100%. (1 -3) Second dissolution step

Instead of the recovery step of (1-2) above, the ethyl acetate phase of the mixed solution in which gold was dissolved in the dissolution step of (1-1) was taken out and the gold was added by adding sodium borohydride. The aqueous phase was reused as the aqueous phase in the next dissolution step.

Except using this aqueous phase, 345 Omg_kg of gold was dissolved in the ethyl acetate phase and 1180 mgZkg of gold was dissolved in the aqueous phase in the second dissolution step performed in the same manner as in (1-1) above. Therefore, it was confirmed that the gold could be collected without waste by repeating the above operations.

Example 2

(2-1) Dissolution process

In 5 g of cyclohexane and 5 of water, 1 mmo 1 of ethylenediamine dihydroaodide and 0.5 mmo 1 of iodine were dissolved. Ethylenediamine dihydroiodide was highly soluble in water and iodine was highly soluble in cyclohexane.

This mixed solution was placed in a reaction vessel, and a 0.2 mm diameter gold wire (0.0408 g) was refluxed and heated near the boiling point for 15 minutes while sufficiently stirring with a stirring blade device. After the heating was completed, the mixture was allowed to stand for 1 minute.After the solvent separated into two phases, each phase was separated and taken out. The concentration of the gold complex dissolved in each solvent was measured. 10 Omg / kg, 260 Omg / kg gold was dissolved in the aqueous phase.

(2-2) Recovery process

Next, hydrazine was added to the aqueous phase in which the gold separated as described above was dissolved as a complex to reduce and recover the gold. The recovery was 100%.

Example 3

(3-1) Dissolution process

In 5 g of methyl ethyl ketone and 5 g of water, 1 mmol of ammonium iodide and 0.5 mmol of iodine were dissolved. Ammonium iodide was highly soluble in water and iodine was highly soluble in methyl ethyl ketone. This mixed solution was put into a reaction tank, and a palladium wire (0.0200 g) having a diameter of 0.2 mm was refluxed and heated at about the boiling point for 15 minutes while sufficiently stirring with a stirring blade device. After heating, the mixture was allowed to stand for 1 minute to separate the solvent into two phases, and the concentration of the palladium complex dissolved in each phase after the separation was measured.The concentration was 290 Omg / kg for the methylethylketone phase and 290 Omg / kg for the aqueous phase. Had 14 Omg / kg of palladium dissolved.

3-2 (Recovery process)

Next, hydrazine was added to methyl ethyl ketone in which palladium separated as described above was dissolved as a complex to reduce and recover palladium, and the recovery was 100%.

Example 4

(4-1) Dissolution process

Potassium iodide (lmmo1) and iodine (0.5 mmol) were dissolved in 5 g of methyl ethyl ketone and 5 g of water. Potassium iodide was highly soluble in water, and iodine was highly soluble in methylethylketone.

This mixed solution was placed in a reaction vessel, and a palladium wire (0.0201 g) having a diameter of 0.2 mm was refluxed and heated at about the boiling point for 15 minutes while sufficiently stirring with a stirring blade device. After heating was completed, the solvent was allowed to stand for 1 minute to separate the solvent into two phases, and the concentration of the palladium complex dissolved in each phase after the separation was measured.

3 10 Omg / kg and 10 OmgZkg of palladium were dissolved in the aqueous phase.

(4-2) Recovery process

Next, sodium borohydride was added to the methyl ethyl ketone phase in which palladium separated as a complex was dissolved as described above to reduce and recover palladium. The recovery was 100%.

(4-3) Solution regeneration process

The separated aqueous phase was acidified, sodium hypochlorite was added to release 0.5 mmo 1 of iodine, and the above methyl ethyl ketone phase was mixed to obtain a regenerating solution.

The palladium wire having a diameter of 0.2 mm is redissolved in this reconstituted solution as described in (4) above. -When the same operation as in 1) was performed, the same solubility as the first time was obtained.

Example 5

(5-1) Dissolution process

Ammonium iodide (1 mmo1) and iodine (0.5 mmo1) were dissolved in carbon tetrachloride (5 g) and water (5) to prepare two solutions having the same composition. Ammonium iodide was highly soluble in water, and iodine was highly soluble in carbon tetrachloride.

Each of these mixed liquids was placed in a separate reaction tank, and while stirring sufficiently with a stirring blade device, a gold wire (0.0804 g) having a diameter of 0.2 mm was added to each, and the mixture was heated at reflux near the boiling point for 15 minutes. After heating was completed, the solution was allowed to stand for 1 minute to separate each solution into two phases, and the concentration of the gold complex dissolved in each phase after the separation was measured. 330 kg / kg of gold was dissolved in the / kg and the aqueous phase, respectively.

(5-2) Recovery process

For one of the two solutions in which gold was dissolved, the aqueous phase and the carbon tetrachloride phase were separated, and sodium hydrogen sulfite was added only to the aqueous phase to reduce and recover the gold.The amount of sodium bisulfite used was approximately 0.026 g.

On the other hand, the other solution in which gold was dissolved was added with sodium bisulfite and the gold was reduced and recovered while coexisting without separating the aqueous phase and the carbon tetrachloride phase.The amount of sodium bisulfite used was It was about 0.048 g.

Based on these comparisons, the amount of reducing agent used is reduced to about 12 in the case of separating and recovering gold by separating the phase in which the gold complex is dissolved at a high concentration, compared to the case where the phase is not separated. It was confirmed that reduction was possible.

(5-3) Solution regeneration process

Sodium hypochlorite is added to the aqueous phase solution from which the gold was recovered by adding the above reducing agent to release iodine, and combined with the separated carbon tetrachloride phase to form a prescribed solution The amount of sodium hypochlorite (5%) used was approximately 0.22 g.

On the other hand, the reducing agent was added without separating the aqueous and carbon tetrachloride phases while keeping both phases coexisting. When sodium hypochlorite was added to the solution from which the gold was recovered to release iodine and regenerated to the prescribed solution composition, the amount of sodium hypochlorite used was about 0.50.

From these comparisons, when the two phases are separated and the specified recovery operation is performed, and the recovered liquid is reused, the amount of the oxidizing agent used is reduced by about 1 to 2 compared to the case where the phases are not separated. It was confirmed that the amount could be reduced.

(5-4) Re-dissolution process

A 0.2 mm diameter gold wire (0.0804 g) was heated to reflux near the boiling point for 15 minutes in the reconstituted lysate. After the heating was completed, the mixture was allowed to stand for 1 minute to separate the solvent into two phases. When the concentration of the gold complex dissolved in the solvent was measured, about 150 mg / kg of gold was dissolved in the carbon tetrachloride phase and about 330 Omg / kg in the aqueous phase.

This confirmed that the reconstituted lysate had the same dissolving capacity as the initial adjusted lysate.

Example 6

In a mixed solvent of 9.5 methyl acetate and 0.5 g of water, 2.5 mmol of ethylenediamine hydrate and 1.25 mmol of iodine were dissolved to prepare a solution. Put this solution into the reaction tank and stir the waste jewelry material (18K necklace: Au ••• 78. 69%, Ag…: I 1.14%, Cu…: I 0.17%) 0. 1432 g was immersed and heated to reflux near the boiling point for about 2.5 hours. After heating until the original shape could not be retained, the components in the solution were measured. Gold was dissolved 100%, copper 28.5%, and silver 7.7%.

Example 7

Ammonium iodide 1 Ommo 1 and iodine 5 mmo 1 were dissolved in a mixed solvent of 40 g of methyl acetate and 10 g of water to prepare a solution.

This solution was put into a reaction tank, and 36. 7036 g of a waste palladium catalyst (grade 3% ··· using alumina pellets as a carrier) was immersed under stirring and heated to reflux near the boiling point for about 2 hours. When the dissolution rate was measured, about 10% of palladium was dissolved, and aluminum was only traces. Next, Examples 8 to 14 corresponding to the second object of the present invention in which a noble metal is selectively dissolved will be described.

Example 8

A solution was prepared by dissolving 1 mmol of tetraethylammonium iodide and 0.5 mm of iodine in 10 g of methanol.

Put this solution into three reaction tanks and stir under agitation. 2 mm diameter gold wire, copper wire, Nigel wire (gold wire 0.0393 g, copper wire 0.0120 g, Nigel wire 0-0130 g) were separately immersed, and each was heated at reflux near the boiling point for 30 minutes.The dissolution state of each metal wire was measured by weight loss.The gold wire dissolved 100%, but the copper wire was dissolved. The dissolution rate was 6.2%, and the dissolution rate of the nickel wire was 3.3%. Example 9

In a mixed solvent of 5 g of methyl acetate and 5 g of water, 1 mmol of tetraethylammonium iodide and 0.5 mmol of iodine were dissolved to prepare a solution.

Put this solution into three reaction tanks and stir under stirring a gold wire, copper wire, and Nigel wire with a diameter of 0.2 mm (gold wire 0.04 18 g, copper wire 0.0233 g, Nigel wire 0 0270 g) were separately immersed, and each was heated at reflux near the boiling point for 15 minutes.The dissolution state of each metal wire was measured. The gold complex was dissolved, but copper and nickel were not dissolved in the reaction bath in which they were immersed and were not detected. The measurement of the complex was performed by ICP emission spectrometry (the same applies to the following examples).

Example 10

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

Also, gold wire prior to dissolving each 2000 ^o C 5 seconds diameter 0. 2 mm was subjected to combustion treatment of copper wire, nickel wire (gold wire 0. 0412 g, copper 0. 0228 g, nickel wire 0 0246 g) was prepared.

The above solution was placed in three reaction tanks, and the gold, copper, and nickel wires subjected to the above combustion treatment were immersed under stirring, and all were heated at reflux near the boiling point for 15 minutes. When the dissolution state of the metal wires was measured, 50 Omg of the gold complex was dissolved in the solution of the reaction vessel in which the gold wire was immersed, but copper and nickel were dissolved in the solution of the reaction vessel in which these were immersed. Without detection.

Example 1 1

A solution was prepared by dissolving ammonium iodide lmmo 1 and iodine 0.5 mmol in a mixed solvent of 5 g of methyl acetate and 5 g of water.

Further, Parajiu beam 10 parts was subjected to combustion treatment in each 2000 ^e C 5 seconds prior to the dissolution, 45 parts of aluminum, were prepared 0. 1 g of the metal material obtained by mixing 45 parts of zinc (powder).

The metal material subjected to the above-mentioned combustion treatment was immersed in the reaction vessel containing the above solution, heated under reflux near the boiling point, and the dissolution state was measured.As a result, 100 pmg of the palladium complex was dissolved in the solution. However, aluminum and zinc did not dissolve and were not detected.

Example 12

A dissolution solution was prepared by dissolving 1 mmo 1 of potassium iodide and 0.5 mmo 1 of iodine in 10 g of methanol.

In addition, 0.1 g of a metal raw material (powder) was prepared by mixing 10 parts of palladium, 45 parts of aluminum, and 45 parts of subaluminum, each of which was subjected to a combustion treatment at 2000 ° C. for 5 seconds before melting.

The metal material subjected to the above combustion treatment was immersed in the reaction vessel containing the above solution, heated under reflux near the boiling point, and the dissolution state was measured.The solution contained 180 Omg Zkg of the palladium complex. but but it had been dissolved, aluminum, zinc ¹ Oh out non-detection does not dissolve

Example 13

Ammonium iodide 2.511111101 and iodine 1.25 mmo 1 were dissolved in a mixed solvent of 8.5 g of ethyl ethyl and 1.5 g of water to prepare a solution.

This solution was placed in a reaction tank, and 0.0478 g of waste jewelry (18 K necklace) was immersed under stirring and heated to reflux near the boiling point for about 80 minutes. I can not stop the original form The solution was allowed to stand still, the solvent was allowed to stand, the solvent was separated into two phases, and the components dissolved in each of the separated phases were measured. The total amount of gold in the ethyl acetate phase was 93%. 3%, silver 1% of total amount and copper 7% of total amount. On the other hand, 6.7% of the total amount of gold, 99% of the total amount of silver and 93% of the total amount of copper were dissolved in the aqueous phase.

Example 14

A solution was prepared by dissolving 2 mm 01 of tetraethylammonium iodide and 1 mmo 1 of iodine in 10 g of methanol.

Put this solution into a reaction tank, immerse 4.9923 g of waste industrial material obtained by applying gold plating to an alloy wire based on an alloy consisting of iron, cobalt and Niggel. Upon heating for about 30 seconds, it was confirmed that the gold color had disappeared and the gold had dissolved. After continuing heating and refluxing for about 3 minutes to confirm the solubility of the base material in the alloy wire, each component in the melt was measured. mg / kg, cobalt was 99 mg / kg, and Nigger was 282 mgZkg.

An aqueous solution of sodium bisulfite (25 w / v-%) 2. Oml was added to the above solution, and the mixture was stirred and left for about 5 hours to recover reduced gold. The residual gold in the solution after the reduction was measured, and was found to be about traces, and the recovery was almost 100%. Industrial applicability

According to the method for dissolving a noble metal using a mixture of two or more solvents having low mutual solubility of the present invention, and further according to the recovery method, the operation is simple as shown in Examples 1 to 7 above. , Gold, silver, platinum group and other precious metals can be recovered efficiently and efficiently with extremely high efficiency, reducing the amount of halogen compounds, simple halogens, and solvents used, and further reducing the amount of repeated use. The following various effects, such as improvement of safety and economy, can be obtained.

(1) When dissolving metals and noble metals, the target metal and the target noble metal can be arbitrarily distributed to the organic solvent phase or aqueous phase. (2) The solvent can be easily separated into two phases (or more), and this can reduce the amount of solvent used in the precious metal recovery process.

③ Along with the above ①, the amount of reducing agent and oxidizing agent used can be reduced.

強 The use of highly acidic substances such as aqua regia and highly toxic substances such as cyanide compounds is not used, and flammability and other problems are not significantly improved by selecting the type of organic solvent and the mixing ratio with water. It can be eliminated and has excellent safety.

単体 Since the halogen alone, the halogen compound and the solvent can be regenerated and reused, the cost of the dissolution and recovery process is greatly improved.

排出 Since discharge from the dissolution and recovery process to the outside of the system can be greatly reduced, the burden on wastewater treatment can be reduced, and the cost can be reduced.

Further, according to the selective dissolution method of the present invention, the operation is simple, and the selective dissolution can be performed without the simultaneous dissolution of the base metal coexisting with the gold, silver, and platinum groups. Since the noble metal is selectively dissolved without substantially dissolving the metal, the subsequent separation and purification step can be omitted or reduced, and the effect of reducing costs can be achieved.

Claims

The scope of the claims

1. A mixture of at least two kinds of solvents selected from an organic solvent and water, wherein at least one solvent constituting the mixture dissolves a simple halogen, and at least one solvent constituting the mixture or the mixture comprises Another solvent dissolves the soluble halogen compound, and at least one solvent constituting the mixture of the parentheses is a mixture comprising a combination of solvents dissolving the polyhalogeno noble metal anion complex. A method for dissolving a metal, comprising dissolving a simple halogen and a soluble halogen compound in a mixed solution having low solubility, and immersing a noble metal raw material while stirring the mixed solution.

2. In claim 1, at least two kinds of solvents forming the mixed solution are a combination of a readily soluble solvent of a polyhalogeno noble metal anion complex and a readily soluble solvent of a simple halogen, and have low mutual solubility of the solvents. A method for melting a metal, comprising:

3. The method for dissolving a metal according to claim 1, wherein the mixture comprises a combination of ethyl acetate and water.

4. The method for dissolving a metal according to claim 1, comprising a combination of cyclohexane and water.

5. The method for dissolving a metal according to claim 1, wherein the mixed liquid comprises a combination of methyl ethyl ketone and water.

6. The method according to claim 1, wherein the mixed solution comprises a combination of carbon tetrachloride and water.

7. Immerse the metal raw material in which the noble metal and the base metal coexist in a solution in which the simple halogen and the soluble halogen compound are dissolved, generate the metal halide by the oxidation reaction of the simple halogen to the metal, and then use the soluble halogen compound to generate the polyhalogeno. In a dissolution method for forming a metal yin complex,

A method for selectively dissolving a metal, comprising using a solvent in which the polyhalogenometal anion complex of a noble metal produced by the above reaction is dissolved, but the base metal is not substantially dissolved.

A metal raw material in which a precious metal and a base metal coexist is immersed in a solution in which a simple halogen and a soluble halogen compound are dissolved, and a metal halide is generated by an oxidation reaction of the simple halogen to the metal. In a dissolution method for forming a polyhalogenogold anion complex with a gen compound,

A method for selectively dissolving a metal, which comprises performing a pretreatment for forming an oxide film on the surface of the base metal as the metal raw material before the dissolution.

Claim 7 or Claim 8, wherein the solution is composed of a polar organic solvent that dissolves a simple halogen and a soluble compound, or a mixed solvent of at least two or more kinds selected from an organic solvent and water. A method for selectively dissolving a metal, comprising:

0. The method for selectively dissolving metals according to claim 9, wherein the dissolving solution is methanol.

1. The method for selectively dissolving metals according to claim 9, wherein the dissolving solution is a mixture of methyl acetate and water.

2. The method according to claim 9, wherein at least two kinds of solvents selected from an organic solvent and water to form a solution as a mixed solvent are a combination of solvents having low mutual solubility. Dissolution method.

3. In claim 12, at least two kinds of solvents constituting the solution as a mixed solvent are a polyhalogeno noble metal anion complex easily soluble solvent and a polyhalogeno noble metal anion complex are hardly soluble and halogen alone is easily soluble. A selective dissolution method of a metal, comprising a combination of the following solvents:

4. In claim 12, at least two kinds of solvents constituting the solution as a mixed solvent are a readily soluble solvent of a polyhalogeno noble metal anion complex, and a poorly soluble polyhalogeno noble metal anion complex and a soluble halogen compound. A method for selectively dissolving a metal, comprising a combination of soluble solvents.

5. The selective recovery of a noble metal, wherein the noble metal is recovered by reducing the polyhalogenometal anion complex in the solution in which the noble metal has been selectively dissolved by any one of claims 7 to 14. Method.

6. A mixture of at least two kinds of solvents selected from an organic solvent and water, and at least one solvent constituting the mixture dissolves a simple halogen and constitutes the solvent or the mixture. At least one other solvent dissolves the soluble haeogen compound, and at least one solvent constituting the mixture of parentheses is a mixture comprising a combination of solvents dissolving the polyhalogeno noble metal anion complex. Dissolving a simple halogen and a soluble halogen compound in a mixed solution having low mutual solubility between solvents, immersing a noble metal material under stirring of the mixed solution to dissolve as a polyhalogeno noble metal anion complex; and after the step, A step of reducing the above-mentioned complex dissolved in any of the solvent phases after standing and separating each solvent and recovering the complex as a noble metal. Dissolution method of recovering the genus.

7. In claim 16, at least two kinds of solvents forming the mixed solution are a combination of a readily soluble solvent of a polyhalogeno noble metal anion complex and a readily soluble solvent of a simple halogen, and the solubility between the solvents is high. A method for dissolving and recovering metals, which is characterized by low cost.

8. The method for dissolving metals according to claim 16, wherein the mixed solution comprises a combination of ethyl acetate and water.

9. The method for dissolving a metal according to claim 16, comprising a combination of cyclohexane and water.

0. The method according to claim 16, wherein the mixed solution comprises a combination of methyl ethyl ketone and water.

1. The method for dissolving a metal according to claim 16, wherein the mixed solution comprises a combination of carbon tetrachloride and water.