JP2016113650A - Selective separation recovery method for gold and palladium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gold and palladium separation method which can separate gold and palladium, from a gold ion-palladium ion solution comprising a plurality of metal ions, with high selectivity in a short time.SOLUTION: A selective separation method for gold and palladium includes a first step in which a noble metal desorbent comprising gold ions and palladium ions is reduced under an acidic condition to deposit and separate gold, and a second step in which the solution obtained in the first step is neutralized and reduced, to deposit and separate palladium.SELECTED DRAWING: None

Description

  The present invention relates to a gold and palladium selective separation and recovery method for selectively separating and recovering gold ions and palladium ions from a solution containing a plurality of metal ions.

  Noble metals such as gold, palladium, platinum, and rhodium are used in industrial catalysts, automobile exhaust gas purification catalysts, and many electrical appliances. Since these noble metals are expensive and useful as resources, they are conventionally collected and reused after use, that is, recycled. Recently, demands for resource conservation have increased, and the importance of recycling precious metals has increased.

  In order to recover precious metals, methods such as precipitation separation, ion exchange, electrolytic deposition, solvent extraction, and adsorption have been developed. Of these, solvent extraction is economical and easy to use. Widely adopted.

  The solvent extraction method includes, for example, an extraction step in which palladium ions are extracted to the organic phase side by bringing the aqueous phase in which palladium ions are dissolved into contact with the organic phase in which the palladium ion extractant is dissolved, and the organic phase is extracted to the organic phase side. It comprises a back extraction step in which palladium ions are back-extracted to the water phase side by bringing the palladium ions into contact with the aqueous phase in which the back extractant is dissolved.

  According to this method, palladium ions can be recovered with high selectivity, and thus are industrially used (see, for example, Patent Documents 1 and 2).

  Further, gold ions are also recovered by the same solvent extraction method as the palladium ions.

  However, since the solvent extraction method uses a large amount of an organic solvent, there are problems in terms of safety and environmental load. In addition, in the method using an extraction solvent such as dialkyl sulfide or dibutyl carbitol generally used in the extraction method, the extraction rate of low-concentration palladium ions and gold ions is insufficient, and high-concentration palladium ions Even if it is a metal ion solution, since extraction speed is slow, it has problems, such as low productivity.

  Therefore, development of a method for separating gold and palladium capable of separating gold and palladium from a gold ion-palladium ion solution containing a plurality of metal ions in a short time and with high selectivity is desired.

  In response to the above problems, the present inventors desorb a palladium ion separating agent that supports a specific functional group on an insoluble carrier and selectively adsorbs palladium ions, and palladium ions adsorbed on the palladium ion separating agent. A desorption agent has been proposed (see, for example, Patent Documents 3 and 4). By using these methods, it is possible to separate and recover palladium from a palladium ion solution containing a plurality of metal ions in a short time and with high selectivity, but there is no description regarding the separation and recovery of gold ions.

Japanese Patent Laid-Open No. 9-279264 JP 2010-59533 A JP 2013-91849 A JP 2012-149344 A

  The present invention has been made in view of the above-described background art, and can separate and recover gold and palladium from a gold ion-palladium ion solution containing a plurality of metal ions in a short time with high selectivity. An object is to provide a method for selectively separating gold and palladium.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have used a novel gold-palladium separation method shown in the present invention, so that from a gold ion-palladium ion solution containing a plurality of metal ions. The inventors have found that gold and palladium can be selectively separated and recovered in a short time and at a high selectivity, and the present invention has been completed.

That is, the present invention has the following gist.
[1] A first step in which a noble metal desorbent solution containing gold ions and palladium ions is reduced under acidic conditions to precipitate and separate gold, and after the first step, the noble metal desorbent solution is neutralized and reduced. And a method for selectively separating gold and palladium, comprising a second step of depositing and separating palladium.
[2] The method for selectively separating gold and palladium according to [1], wherein the acidic condition in the first step is pH 1 to 6, and the neutralizing condition in the second step is pH 6 or more.
[3] The above-mentioned [1] or [3], wherein the noble metal desorbent solution containing gold ions and palladium ions is obtained by bringing a noble metal desorbent into contact with a noble metal separating agent adsorbing gold ions and palladium ions. [2] The method for selectively separating gold and palladium as described in [2].
[4] The method for selectively separating gold and palladium according to any one of the above [1] to [3], wherein the precious metal desorbing agent is DL-methionine.
[5] The method for selectively separating gold and palladium as described in [3] or [4] above, wherein the functional group represented by the general formula (1) is bonded to the support in the noble metal separating agent.

（式中、Ｒは炭素数１〜１８の鎖式炭化水素基、炭素数３〜１０の脂環式炭化水素基、炭素数６〜１４の芳香族炭化水素基、カルボキシルメチル基、又はカルボキシエチル基を表し、ｎは１〜４の整数を表す。Ｚはアミド結合を表す。）
［６］一般式（１）で示される官能基が、一般式（２）で示される官能基であることを特徴とする前記［５］に記載の金とパラジウムの選択的分離方法。

(In the formula, R is a chain hydrocarbon group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 14 carbon atoms, a carboxylmethyl group, or carboxyethyl. And n represents an integer of 1 to 4. Z represents an amide bond.)
[6] The method for selectively separating gold and palladium according to the above [5], wherein the functional group represented by the general formula (1) is a functional group represented by the general formula (2).

（式中、Ｒは炭素数１〜１８の鎖式炭化水素基、炭素数３〜１０の脂環式炭化水素基、炭素数６〜１４の芳香族炭化水素基、カルボキシルメチル基、又はカルボキシエチル基を表し、ｎは１〜４の整数を表す。）
［７］一般式（１）又は（２）で示される官能基において、ｎが１の整数であることを特徴とする前記［５］又は［６］に記載の金とパラジウムの選択的分離方法。
［８］一般式（１）又は（２）で示される官能基が、メチレン基、エチレン基、炭素数３〜８の直鎖、分岐若しくは環状のアルキレン基、又は炭素数６〜１４のアリーレン基を介して担体に結合していることを特徴とする前記［５］乃至［７］のいずれかに記載の金とパラジウムの選択的分離方法。
［９］一般式（１）又は（２）で示される官能基が、ｎ−プロピレン基を介して担体に結合していることを特徴とする前記［５］乃至［８］のいずれかに記載の金とパラジウムの選択的分離方法。
［１０］担体が無機担体であることを特徴とする前記［５］乃至［９］のいずれかに記載の金とパラジウムの選択的分離方法。
［１１］担体がシリカゲルであることを特徴とする前記［５］乃至［１０］のいずれかに記載の金とパラジウムの選択的分離方法。

(In the formula, R is a chain hydrocarbon group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 14 carbon atoms, a carboxylmethyl group, or carboxyethyl. Represents a group, and n represents an integer of 1 to 4.)
[7] The method for selectively separating gold and palladium as described in [5] or [6] above, wherein n is an integer of 1 in the functional group represented by the general formula (1) or (2) .
[8] The functional group represented by the general formula (1) or (2) is a methylene group, an ethylene group, a linear, branched or cyclic alkylene group having 3 to 8 carbon atoms, or an arylene group having 6 to 14 carbon atoms. The method for selectively separating gold and palladium according to any one of [5] to [7], wherein the gold and palladium are bonded to a carrier via
[9] The functional group represented by the general formula (1) or (2) is bonded to the carrier via an n-propylene group, and is described in any one of the above [5] to [8] For selective separation of gold and palladium.
[10] The method for selectively separating gold and palladium as described in any one of [5] to [9] above, wherein the carrier is an inorganic carrier.
[11] The method for selectively separating gold and palladium as described in any one of [5] to [10] above, wherein the support is silica gel.

  According to the present invention, it is possible to selectively separate and recover gold and palladium from a gold ion-palladium ion solution containing a plurality of metal ions in a short time and with high selectivity.

  Further, the adsorbent and desorbent used in the present invention can be used repeatedly, and an organic solvent is not essential. As a result, gold and palladium can be separated and recovered economically without imposing an environmental burden.

  Hereinafter, the present invention will be described in detail.

  The method for selectively separating and recovering gold and palladium according to the present invention was obtained in the first step in which a noble metal desorbent solution containing gold ions and palladium ions was reduced under acidic conditions to precipitate and separate gold. It consists of a second step of neutralizing and reducing the noble metal desorbent solution to precipitate and separate palladium.

  In the first step of reducing the noble metal desorbent solution containing gold ions and palladium ions and precipitating and separating gold, it is necessary to reduce them under acidic conditions so that palladium is not simultaneously reduced and precipitated. As the acidic conditions, from the viewpoint of reduction precipitation of gold and precipitation of palladium, preferably pH 1 to 6, particularly preferably pH 2 to 5, is advantageous in terms of reduction efficiency of gold and selective separation of gold.

  The operation of the reduction treatment of the gold ion desorption solution is usually carried out under normal pressure and atmospheric atmosphere, and can also be carried out under pressurized or reduced pressure conditions and inert gas atmosphere. The operation of the reduction treatment is usually performed in a temperature range of 4 to 100 ° C, and a temperature range of 10 to 60 ° C is more preferable.

  In the second step of reducing and precipitating palladium, the metal palladium is preferably obtained by reduction at pH 6 or more, particularly preferably at pH 8 to 12.

  The reduction treatment of the palladium ion desorption solution is usually carried out under normal pressure and atmospheric atmosphere, and can also be carried out under pressurized or reduced pressure conditions and inert gas atmosphere. The operation of the reduction treatment is usually performed in a temperature range of 4 to 100 ° C, and a temperature range of 40 to 80 ° C is more preferable.

  The precious metal desorbent solution containing gold ions and palladium ions used in the present invention is preferably a precious metal desorbent solution obtained by bringing a precious metal desorbent into contact with a precious metal separating agent that has adsorbed gold ions and palladium ions. As the noble metal desorbing agent, DL-methionine is preferable. The noble metal desorbing agent is preferably used as a noble metal desorbing solution in an aqueous solution such as hydrochloric acid. Mineral acids other than hydrochloric acid may cause insufficient reduction of gold or palladium. The concentration of DL-methionine is not particularly limited, and for example, preferably 1 to 10% by weight, particularly preferably 1 to 5% by weight is selected from the viewpoint of solubility in water.

  The amount of the noble metal desorbent used is not particularly limited. For example, it is preferably 2 to 10000 times mol, and 5 to 1000 times mol is desorbed with respect to 1 mol of sulfur in the noble metal separating agent used in the present invention. It is particularly preferable in terms of efficiency and economy.

  A noble metal desorbent solution containing gold ions and palladium ions obtained by bringing the noble metal desorbent into contact with the above-described noble metal separating agent adsorbing gold ions and palladium ions is obtained.

  As a reduction method for the noble metal desorbent solution containing gold ions and palladium ions, a chemical reduction method in which a reducing agent such as hydrazine or ferrous chloride is added is preferable. The reducing agent used in the present invention is not particularly limited, and it is particularly preferable to use hydrazine in that no metal is mixed in the gold and palladium that have been reduced and precipitated.

  The neutralizing agent for neutralizing the noble metal desorbent solution containing gold ions and palladium ions in the second step of reducing and precipitating palladium is not particularly limited, and may be sodium hydroxide, potassium hydroxide, etc. in terms of solubility. Alkali metal hydroxides can be preferably used.

  Examples of the method for filtering the reduced and precipitated gold and palladium include a method using a membrane filter, filter paper, filter cloth, glass filter and the like, and filtration with a membrane filter or filter paper is preferable from the viewpoint of ease of operation.

  Gold and palladium obtained by filtration can be separated as a high-purity metal of 99% or more by heating and melting above the melting point of each metal.

  As the noble metal separating agent, one that adsorbs gold ions and palladium ions and hardly adsorbs other metals is preferable. For example, it is particularly preferable that the functional group represented by the general formula (1) is bonded to the carrier.

（式中、Ｒは炭素数１〜１８の鎖式炭化水素基、炭素数３〜１０の脂環式炭化水素基、炭素数６〜１４の芳香族炭化水素基、カルボキシルメチル基、又はカルボキシエチル基を表し、ｎは１〜４の整数を表す。Ｚは、−ＣＯＮＨ−で表わされるアミド結合を表す。）
また、一般式（１）で示される官能基が、一般式（２）で示される官能基であることが好ましい。

(In the formula, R is a chain hydrocarbon group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 14 carbon atoms, a carboxylmethyl group, or carboxyethyl. And n represents an integer of 1 to 4. Z represents an amide bond represented by -CONH-.)
Moreover, it is preferable that the functional group shown by General formula (1) is a functional group shown by General formula (2).

（式中、Ｒは炭素数１〜１８の鎖式炭化水素基、炭素数３〜１０の脂環式炭化水素基、炭素数６〜１４の芳香族炭化水素基、カルボキシルメチル基、又はカルボキシエチル基を表し、ｎは１〜４の整数を表す。）
一般式（１）及び（２）で示される官能基において、Ｒは炭素数１〜１８の鎖式炭化水素基、炭素数３〜１０の脂環式炭化水素基、炭素数６〜１４の芳香族炭化水素基、カルボキシルメチル基、又はカルボキシルエチル基を表す。

(In the formula, R is a chain hydrocarbon group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 14 carbon atoms, a carboxylmethyl group, or carboxyethyl. Represents a group, and n represents an integer of 1 to 4.)
In the functional groups represented by the general formulas (1) and (2), R represents a chain hydrocarbon group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and an aromatic having 6 to 14 carbon atoms. Represents a group hydrocarbon group, a carboxymethyl group, or a carboxyethyl group.

  The chain hydrocarbon group having 1 to 18 carbon atoms is not particularly limited, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group. , Undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group (cetyl group), heptadecyl group, octadecyl group (stearyl group), oleyl group, elaidyl group, isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, 2-ethylhexyl group, vinyl group, allyl group, 1-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 2-methylallyl group 1-heptynyl group, 1-hexenyl group, 1-heptenyl group, 1-octenyl Group, 2-methyl-1-propenyl group.

  The alicyclic hydrocarbon group having 3 to 10 carbon atoms is not particularly limited, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cyclodecyl group, and the like. A hexenyl group, a cyclohexadienyl group, a cyclooctenyl group, a cyclooctadienyl group, etc. are mentioned.

The aromatic hydrocarbon group having 6 to 14 carbon atoms is not particularly limited, and examples thereof include a phenyl group, a naphthyl group, an anthryl group, a tolyl group, a xylyl group, a cumenyl group, a benzyl group, a phenethyl group, a styryl group, and a cinnamyl group. , Biphenylyl group, phenanthryl group and the like.
R is preferably a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a phenyl group or a benzyl group, and more preferably an ethyl group, a propyl group, an isopropyl group, a phenyl group or a benzyl group, more preferably an ethyl group. Group and propyl group are preferred.

  In the functional groups represented by the general formulas (1) and (2), n represents an integer of 1 to 4, and is preferably 1.

  In the functional group represented by the general formula (1), Z represents an amide bond. Here, an amide bond and a bond represented by —CO—NH— are shown, and the direction of the bond is not limited, and the direction represented by the general formula (2) is preferable.

  The functional group represented by the general formula (1) or (2) is a methylene group, an ethylene group, a linear, branched or cyclic alkylene group having 3 to 8 carbon atoms, or an arylene group having 6 to 14 carbon atoms. It is particularly preferred that it is bound to a carrier.

  The linear or branched alkylene group having 3 to 8 carbon atoms is not particularly limited, and examples thereof include a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, and an octylene group. These may be linear or branched. The bonding position of the amide group is not particularly limited as long as it is on the carbon of the alkylene group.

  Examples of the cyclic alkylene group having 3 to 8 carbon atoms include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclohexenylene group, and a cyclohexadienylene group. , Cyclooctenylene group, cyclooctadienylene group and the like. Also in the cyclic alkylene group, the bonding position of the amide group is not particularly limited as long as it is on the carbon of the cycloalkylene group.

  Examples of the arylene group having 6 to 14 carbon atoms include a phenylene group, a naphthylene group, an anthrylene group, a tolylene group, a xylylene group, a cumenylene group, a benzylene group, a phenylene group, a styrylylene group, a cinnamylene group, a biphenylylene group, and a phenanthrylene group. Etc. Also in the arylene group, the bonding position of the amide group is not particularly limited as long as it is on the carbon of the arylene group.

  Of these, n-propylene groups are most preferred.

  Any carrier that is insoluble in the solvent can be used without particular limitation. The carrier that can be used is not particularly limited. For example, inorganic carriers such as silica gel, alumina, titania, magnesia, zirconia, iron oxide, copper oxide, glass, silica sand, talc, mica, clay, wollastonite; styrene polymer, styrene -Polystyrene polymers such as crosslinked divinylbenzene; Polyolefins such as polyethylene, polypropylene and polyvinyl chloride; Acrylic polymers such as polymethyl methacrylate and polyethyl acrylate; Polylysine particles, polyvinylamine particles, polymethylglutamic acid, polyvinyl alcohol And the like, and the like. Of these carriers, inorganic carriers are preferable in terms of chemical resistance and price, and silica gel is particularly preferable in terms of high versatility.

  Next, a method for adsorbing gold and palladium on the noble metal separating agent will be described.

  The method for adsorbing gold ions and palladium ions to the noble metal separating agent is performed by bringing the noble metal separating agent into contact with a solution containing gold ions and palladium ions.

  The method for bringing the solution containing gold ions and palladium ions into contact with the noble metal separating agent is not particularly limited. For example, a slurry containing a solution containing gold ions and palladium ions and the noble metal separating agent is prepared, The method (fluidized bed) which stirs this is mentioned. In addition, a method (fixed bed) in which a noble metal separating agent is packed in a column or the like and a solution containing gold and palladium ions is circulated and brought into contact therewith can be mentioned.

  In the above-described method for adsorbing gold ions and palladium ions, the solution containing gold ions and palladium ions to be brought into contact with the noble metal separating agent is not particularly limited. For example, a solution in which jewelry is dissolved, or a platinum group metal wet solution A solution after acid leaching in the refining process is mentioned.

  The above solution containing gold ions and palladium ions contains, in addition to gold and palladium ions, platinum group metal ions such as platinum ions and rhodium ions, base metal ions such as copper ions, iron ions, nickel ions and zinc ions. May be. When this solution is brought into contact with the noble metal separating agent exemplified in the present invention, gold and palladium ions are selectively adsorbed.

  The solution containing gold ions and palladium ions is not particularly limited, and an aqueous solution is preferably used in terms of environmental load.

  The liquid property of the solution containing gold ions and palladium ions is not particularly limited, and is preferably acidic. There is no limitation in particular as an acid used in order to make the solution containing gold ion and palladium ion acidic, For example, inorganic acids, such as hydrochloric acid, a sulfuric acid, nitric acid, are mentioned. Of these, hydrochloric acid is particularly preferred because it is used as an acid leaching solution for gold ions and palladium ions.

  There is no limitation in particular as acid concentration in the solution containing a gold ion and a palladium ion, 0.1-10 mol / L (liter) is preferable and 0.1-5 mol / L is more preferable. If the acid concentration is within this range, gold ions and palladium ions can be adsorbed without impairing the adsorption efficiency of the noble metal separating agent.

  In the adsorption method of gold ions and palladium ions, the amount of the noble metal separating agent used in the present invention is the amount of sulfur in the noble metal separating agent with respect to a total of 1 mol of gold and palladium ions in the solution containing the gold ions and palladium ions. Is preferably 0.1 to 100 times mol, more preferably 0.5 to 10 times mol.

The present invention will be specifically described below, but the present invention is not construed as being limited by these examples.
(Analysis method)
1. The metal ion concentration in the aqueous solution was measured with an ICP emission spectroscopic analyzer (OPTIMA 3300 DV, manufactured by Perkin Elmaer).

  2. The nitrogen content was measured with a fully automatic elemental analyzer (2400II, manufactured by PerkinElmer Japan).

  3. The sulfur content was measured by ion chromatography. Ion chromatography measurement was performed with the following pretreatment, apparatus, and measurement conditions.

Pretreatment: The sample was introduced into an automatic sample combustion apparatus (AQF-100, manufactured by Mitsubishi Chemical Analytic Co., Ltd.), and SO ₄ ²⁻ produced by combustion was collected in an adsorbent (internal standard material PO ₄ ⁻ ).

Measuring device: IC-2001 manufactured by Tosoh Corporation
Separation column: TSKgel SuperIC-AP (4.6 mmΦ × 150 mm)
Detector: Electrical conductivity detector Eluent: 2.7 mmol / L NaHCO ₃ and 1.8 mmol / L Na ₂ CO ₃
4). The average pore diameter of the noble metal separating agent was measured by a nitrogen adsorption method according to the BET method using a measuring device (model: BELSORP-mini) manufactured by Japan BEL.

  5. The average particle diameter of the noble metal separating agent was measured by a laser diffraction method using Microtrac MT3300 manufactured by Nikkiso Co., Ltd.

Reference example 1
Preparation of Gold and Palladium Separation Agents Used in Examples 1 to 4 and Comparative Example 1 The noble metal separation agent represented by the chemical formula (5) schematically including the bonding of the functional group to the carrier is the following method Prepared according to

ディーン・スターク装置付き５００ｍＬナス型フラスコに、シリカゲル（富士シリシア化学社製、商品名：ＰＳＱ６０Ｂ）１００ｇ、水５ｇ、及びｏ（オルト）−キシレン ２００ｇを量り取り、６０℃で激しく攪拌しながら、予め調製しておいた３−アミノプロピルトリメトキシシラン ３５．９ｇとｏ−キシレン ３５．９ｇの混合溶液を１０分間かけて滴下した後、９０℃まで昇温し、１時間攪拌した。次に、１１０℃まで昇温し、１．５時間攪拌した。ディーン・スターク装置に溜まったメタノール、ｏ−キシレン、及び水の混合溶液は系外に廃棄した。

In a 500 mL eggplant-shaped flask equipped with a Dean-Stark apparatus, 100 g of silica gel (manufactured by Fuji Silysia Chemical Co., Ltd., trade name: PSQ60B), 5 g of water, and 200 g of o (ortho) -xylene are weighed and stirred in advance at 60 ° C. A prepared mixed solution of 35.9 g of 3-aminopropyltrimethoxysilane and 35.9 g of o-xylene was dropped over 10 minutes, and then the temperature was raised to 90 ° C. and stirred for 1 hour. Next, it heated up to 110 degreeC and stirred for 1.5 hours. The mixed solution of methanol, o-xylene, and water collected in the Dean-Stark apparatus was discarded outside the system.

  Next, 0.005 g of 3,5-bis (trifluoromethyl) phenylboronic acid and 48 g of (ethylthio) acetic acid were weighed and heated to reflux for 24 hours with vigorous stirring. After cooling to room temperature, the reaction mixture was filtered, and the collected solid was washed with methanol to obtain a noble metal separating agent.

Sulfur content 1.34 mmol / g, nitrogen content 1.43 mmol / g
Average pore diameter 4μm, average particle diameter 60μm
Using the noble metal separating agent obtained in Reference Example 1, selective recovery of gold and palladium was evaluated.

  In addition, the adsorption liquid used for evaluation of separation performance is as follows.

    Adsorbing solution: 1M hydrochloric acid solution containing 200 mg / L each of gold, palladium, platinum and rhodium.

  The noble metal desorption solution used for the evaluation of the separation performance is a 5% hydrochloric acid aqueous solution of 5% DL-methionine.

  The adsorption / desorption rate of gold ions and palladium ions was calculated by the following formula.

Gold adsorption / desorption rate (%) = Amount of gold adsorbed / desorbed on noble metal separating agent ÷ Amount of gold ion contacted with noble metal separating agent × 100%
Palladium adsorption / desorption rate (%) = Palladium ion adsorbed / desorbed on precious metal separating agent ÷ Palladium ion contacted with precious metal separating agent × 100%
Moreover, the gold selectivity and the palladium selectivity were calculated by the following formulas.

Gold selectivity (%) = amount of gold deposited ÷ total amount of metal deposited × 100%
Palladium selectivity (%) = amount of precipitated palladium / amount of precipitated metal × 100%
Further, the gold recovery rate and the palladium recovery rate were calculated by the following formulas.

Gold recovery rate (%) = Amount of deposited gold / Amount of gold contacted with precious metal separating agent × 100%
Palladium recovery rate (%) = amount of precipitated palladium / amount of palladium contacted with a precious metal separating agent × 100%
Examples 1-4, Comparative Example 1
Noble metal adsorption / desorption process:
0.24 g of the noble metal separating agent obtained in Reference Example 1 was packed in a glass column having a diameter of 5 mm and a length of 5 cm. Next, 10 mL of 1 mol / L hydrochloric acid aqueous solution was supplied from the top of the column using a peristaltic pump. Next, 50 mL of the adsorbed liquid is passed through the column at a flow rate of SV = 30 hr ⁻¹ , then 10 mL of 1M hydrochloric acid is passed at the same liquid passing speed, and both liquids are combined and separated from the column outlet. The amount of gold ion, palladium ion, platinum ion and rhodium ion in the medium was measured, and the amount of gold ion, palladium ion, platinum ion and rhodium ion adsorbed on the noble metal separating agent was calculated. Next, 7 mL of the precious metal desorption solution is passed through the column at a flow rate of SV = 30 hr ⁻¹ , 7 mL of 1M hydrochloric acid is passed through at the same flow rate, and both solutions are separated from the column outlet and separated. The amount of gold ion, palladium ion, platinum ion and rhodium ion in the medium was measured, and the amount of gold ion, palladium ion, platinum ion and rhodium ion desorbed from the noble metal separating agent was calculated. Here, SV is represented by the following equation.

SV (hr ⁻¹ ) = flow rate (mL / hr) ÷ volume of precious metal separating agent packed in the column (mL)
Noble metal reduction deposition process:
0.19 g of reducing agent hydrazine pentahydrate was added to the noble metal desorbent solution containing gold ions and palladium ions obtained in the noble metal adsorption / desorption step, and the pH was adjusted to 1 to 8 with an 8 mol / L aqueous sodium hydroxide solution. Prepared and stirred at 50 ° C. for 10 minutes. After allowing to cool to room temperature, the liquid was filtered and the filtrate was collected. The amount of gold ion, palladium ion, platinum ion, and rhodium ion in the filtrate was measured, and the reduced metal species and the amount of metal were calculated (first step).

  The filtrate obtained above was adjusted to pH 10 with an aqueous 8 mol / L sodium hydroxide solution as a neutralizing agent and stirred at 80 ° C. for 30 minutes (neutralization reduction). After cooling to room temperature, the liquid was filtered to obtain a filtrate. The amount of gold ion, palladium ion, platinum ion, and rhodium ion in the filtrate was measured, and the reduced metal species and the amount of metal were calculated (second step).

  The results are shown in Table 1.

  In the noble metal adsorption / desorption step, a noble metal desorption solution containing gold ions and palladium ions was obtained. Examples 1 to 4 are examples in which reduction treatment was performed by the method of the present invention, but gold and palladium could be selectively separated.

  On the other hand, unlike Comparative Example 1, Comparative Example 1 is an example in which gold is made alkaline when reducing and precipitating, but gold and palladium cannot be selectively separated.

  Provided is a method for selective separation of gold and palladium capable of separating gold and palladium from a gold ion-palladium ion solution containing a plurality of metal ions in a short time and with high selectivity.

  The gold and palladium separation method of the present invention can separate gold and palladium from a gold ion-palladium ion solution in a short time and with high selectivity, and can be widely used in the field of precious metal recovery from the viewpoint of environmental conservation. it can.

Claims (11)

  A first step of reducing a noble metal desorbent solution containing gold ions and palladium ions under acidic conditions to precipitate and separate gold; and after the first step, the noble metal desorbent solution is neutralized and reduced, and palladium A method for selectively separating gold and palladium, which comprises a second step of precipitating and separating the material.   The method for selectively separating gold and palladium according to claim 1, wherein the acidic condition in the first step is pH 1 to 6, and the neutralizing condition in the second step is pH 6 or more.   The noble metal desorbent solution containing gold ions and palladium ions is obtained by bringing a noble metal desorbent into contact with a noble metal desorbent adsorbing gold ions and palladium ions. For selective separation of gold and palladium.   The method for selectively separating gold and palladium according to any one of claims 1 to 3, wherein the precious metal desorbing agent is DL-methionine. 5. The method for selectively separating gold and palladium according to claim 3, wherein the noble metal separating agent has a functional group represented by the general formula (1) bonded to a support.

(In the formula, R is a chain hydrocarbon group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 14 carbon atoms, a carboxylmethyl group, or carboxyethyl. And n represents an integer of 1 to 4. Z represents an amide bond.) The method for selectively separating gold and palladium according to claim 5, wherein the functional group represented by the general formula (1) is a functional group represented by the general formula (2).

(In the formula, R is a chain hydrocarbon group having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 14 carbon atoms, a carboxylmethyl group, or carboxyethyl. Represents a group, and n represents an integer of 1 to 4.)   7. The method for selectively separating gold and palladium according to claim 5, wherein n is an integer of 1 in the functional group represented by the general formula (1) or (2).   The functional group represented by the general formula (1) or (2) is via a methylene group, an ethylene group, a linear, branched or cyclic alkylene group having 3 to 8 carbon atoms, or an arylene group having 6 to 14 carbon atoms. The method for selectively separating gold and palladium according to any one of claims 5 to 7, wherein the gold and palladium are bonded to a carrier.   The gold according to any one of claims 5 to 8, wherein the functional group represented by the general formula (1) or (2) is bonded to the carrier via an n-propylene group. A method for selective separation of palladium.   10. The method for selectively separating gold and palladium according to claim 5, wherein the carrier is an inorganic carrier.   The method for selectively separating gold and palladium according to any one of claims 5 to 10, wherein the carrier is silica gel.