JP2006193763A - Method for separating and recovering noble metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new method for separating and recovering noble metals where, from a material comprising a plurality of noble metals and base metals, each noble metal can be efficiently separated in a pure state by a simple operation using an adsorption/elution agent inexpensively obtainable in large amounts, and easily regenerative after use, and which is suitable for performing on an industrial scale. <P>SOLUTION: Individual noble metals are classified and isolated at high purity from a material comprising a plurality of noble metals and base metals through: a step (a) where the material is dissolved with hydrochloric acid; a step (b) where the hydrochloric acid solution obtained by the step (a) is passed through a cellulose column, so as to adsorb noble metals; a step (c) where, from the cellulose with the noble metals adsorbed, the noble metals belonging to the first group are classified and recovered using a mixture of hydrochloric acid and 2-propanone as a development/elution agent; and a step (d) where the noble metals belonging to the second group are classified and recovered using a mixture of hydrochloric acid and 1-butanol as a development/elution agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a method for separating and recovering noble metals, more specifically, the present invention is a material containing a plurality of noble metals and base metals, such as precious metal ores, used automobile exhaust gas purification catalysts, electronic parts, denture materials, etc. Therefore, the present invention relates to a method for separately isolating and recovering each noble metal in a pure state.

  The industrial methods for separating and recovering precious metals such as gold, platinum, palladium, rhodium, iridium and ruthenium from the materials they contain have been electrolysis, chemical conversion, ion exchange. A wide variety of methods are known such as a solvent extraction method, an adsorption method, or a combination of these methods.

For example, in order to separate and recover gold from the ore, after melting it and separating the gold-containing components, this is treated with hydrochloric acid and chlorine or aqua regia to make a gold salt-containing aqueous solution, and then containing these gold salts A method of electrolyzing an aqueous solution to separate and recover gold (see Patent Document 1), a method of treating a gold salt-containing aqueous solution with an ion exchange resin (see Patent Document 2), and a method of solvent extraction using dibutyl carbitol (Patent Document) (Ref. 3), solvent extraction with 4-methyl-2-pentanone, adsorption to chelate resin, recovery (see Patent Document 4), recovery by adsorption to peat peat (Ref. Patent Document 5), etc. Are known.
According to these methods, since gold is recovered as a gold salt, it is finally necessary to further reduce it and convert it to gold.

  On the other hand, as a method for separating and recovering each noble metal from a material containing a plurality of noble metals, for example, a solution containing at least two kinds of noble metal chlorides is converted into at least one chromatograph containing a solid adsorbent having one or more Kd. Is used to adsorb a noble metal, and then elute the adsorbent adsorbing the noble metal with a halide salt solution to obtain a fraction containing only a single metal in the order of Ru, Rh, Pd, Pt, Ir, and Cs. (See Patent Document 6), a noble metal-containing halide feedstock solution is passed through a chromatographic medium, the noble metal is adsorbed on this medium, and each fraction contains at least one noble metal using an eluent. A method of mutual separation of noble metals that separates Ir and Ru ions as trivalent oxidation states during fractionation (see Patent Document 7), including chloro complexes of Ir and one or more other noble metals. When the acidic solution is passed through at least one chromatography column containing a solid absorbent and eluted into one or more fractions containing one or more noble metals, and Ir is separated from the other noble metal mixture. , Ir is present in a tetravalent oxidation state on the column, which is reduced from tetravalent to trivalent on the column, and the iridium (III) chloro complex is eluted from chloro complexes of other noble metals (patents) Reference 8), (a) adjusting the acidity of the feedstock solution to the range of 5.5 to 6.5 MHCl, (b) adjusting the redox potential of the feedstock solution to at least about 500 mV, (c) ) Passing the chromatographic medium through a solution with adjusted acidity and redox potential, allowing base metal, other impurity elements and platinum group metals to interact with the chromatographic medium; and (d) eluent. A method of separating platinum group metals from each other by eluting at least platinum and palladium from a medium during fractionation (see Patent Document 9), and separating a noble metal from its halide solution by glycol methacrylate chromatography. A method is known in which a noble metal is adsorbed on the medium by passing this solution through a graph medium, and then the adsorbed noble metal is eluted into a plurality of fractions using an acidic solution (see Patent Document 10).

  However, each of these methods must use a special adsorbent and eluent, which is inevitably costly and has a disadvantage that the separation operation is complicated and the separation efficiency is low. As an industrial separation method of precious metals, it was not always satisfactory.

  Therefore, it is not necessary to use an inexpensive adsorbent that is easily available, and no expensive eluent, and each precious metal can be isolated with a simple operation. A method has been desired in this field.

By the way, cellulose is an inexpensive adsorbent that is easily available, and some examples of separating noble metals using this cellulose have been reported. For example, after separating platinum by column chromatography of cellulose, and further passing a concentrated hydrochloric acid mixture of platinum, palladium, rhodium and iridium through cellulose, and developing using 4-methyl-2-pentanone as the mobile phase First, platinum and iridium elute, then palladium elutes, and finally rhodium elutes. By removing 4-methyl-2-pentanone from these eluates, the respective noble metal chlorides are obtained. It has been reported (see Non-Patent Documents 1 and 2).
However, in this case as well, a special eluent must be used, the operation is complicated, the separation efficiency is low, and it is completely unsuitable for industrial implementation.

US Pat. No. 4,229,270 (Claims and others) US Pat. No. 4,543,169 (Claims and others) US Pat. No. 4,390,366 (Claims and others) US Pat. No. 4,762,556 (Claims and others) US Pat. No. 4,936,910 (Claims and others) US Pat. No. 4,885,143 (Claims and others) JP-A-9-133670 (Claims and others) JP 2001-98335 A (Claims and others) JP 2001-516808 A (Claims and others) JP 2002-303614 A (Claims and others) “Analytica Himika Acta” (Anal. Chim. Acta), 1958, pp. 129-131 S. Eye. S. I. Ginzburg et al., “Analytical Chemistry of Platinum Metals”, New York City, Willy & Sons (NY Wiley & Sons), 1975. Pp. 466-479

  In the present invention, an adsorbent and an eluent that can be obtained in large quantities and at low cost from materials containing a plurality of noble metals and base metals, and that can be easily regenerated after use, can be efficiently used for each noble metal. The object of the present invention is to provide a novel method for separating and recovering noble metals that can be separated in a pure state and is suitable for implementation on an industrial scale.

  As a result of intensive research to develop an industrially feasible separation and recovery method for precious metals capable of separating and recovering individual precious metals with high purity from materials containing a plurality of precious metals and base metals, By using cellulose as an agent and using 2-propanone and 1-butanol as developing eluents, it was found that the object could be achieved, and the present invention was made based on this finding.

That is, the present invention
(A) a step of dissolving a material containing a plurality of noble metals and base metals in hydrochloric acid;
(B) passing the hydrochloric acid solution obtained in step (a) through a cellulose column and adsorbing a noble metal;
(C) a step of separating and recovering noble metals belonging to the first group by using a mixture of hydrochloric acid and 2-propanone as a developing and eluent, and (ii) hydrochloric acid and 1-butanol; The separation and isolation of individual noble metals with high purity from materials containing a plurality of noble metals and base metals, comprising the step of separating and recovering noble metals belonging to the second group using a mixture of The present invention provides a method for separating and recovering precious metals.

Next, the method of the present invention will be described in more detail.
In the method of the present invention, a material containing a plurality of precious metals and base metals is used as a raw material. Examples of such materials include precious metal raw ore and automobile exhaust gas purification that must be disposed of. Catalyst, synthetic reaction catalyst, electrolysis electrode, electronic component, denture material and the like. Examples of the ore include gold mine, platinum ore, and nickel ore residue.

  In the step (a) of the method of the present invention, a material containing a noble metal is dissolved in hydrochloric acid to obtain a hydrochloric acid solution. Precious metals are stable to acids and do not dissolve in hydrochloric acid, but dissolve in the presence of an oxidizing agent to form a chloride hydrochloric acid solution. As the oxidizing agent at this time, chlorine, concentrated nitric acid, and perchlorate are used. A mixture of 3 volumes of concentrated hydrochloric acid and 1 volume of concentrated nitric acid is so-called aqua regia and dissolves most precious metals such as gold and platinum well. Since silver reacts with hydrochloric acid and precipitates as silver chloride, it is removed using solid-liquid separation means such as filtration and centrifugation.

  When dissolved using this aqua regia, the obtained solution is heated to a temperature of around 100 ° C., and after removing nitric acid by bubbling air or an inert gas, the step (b) is performed. preferable. Next, in step (b), a hydrochloric acid solution containing the noble metal obtained in step (a) is passed through a column packed with cellulose as an adsorbent. The liquid passing speed at this time is preferably 15 to 40 ml / hr per unit area.

In this case, the cellulose to be used may be of any origin such as natural cellulose, regenerated cellulose, mercerized cellulose, etc., but it has a high α-cellulose content and is used as a filler for ordinary partition chromatography. You can choose from any. Especially preferred are granular celluloses suitable as column fillers. The cellulose is preferably used as a powder having a particle size that can be carried out on an industrial scale, that is, a bulk specific gravity of 0.15 to 0.40 g / ml, but a fibrous one can also be used if desired. The fibrous material is preferably fibrillated.
In this step (b), the metal contained in the hydrochloric acid solution is adsorbed on the cellulose including the base metal.

  Next, the cellulose column thus adsorbed with metal is separated and collected in the step (c) using a mixture of hydrochloric acid and 2-propanone as eluent and eluent first. To do. As a developing and eluent in this case, a mixture of hydrochloric acid and 2-propanone having a concentration of 2 to 12 M, preferably 2 to 10 M, and a volume ratio of 1 to 5 to 1 to 10 is used.

  Since the precious metals of the first group, that is, rhodium and palladium, are eluted by the treatment in the step (c), the fraction of the flowing metal is fractionated and recovered while being detected by ultraviolet spectroscopy or other means.

  In this way, after the first group of noble metals is recovered, then in step (d), the developing and eluents are replaced with a mixture of hydrochloric acid and 1-butanol, and likewise belong to the second group of noble metals. Collect at least one species separately. As a developing and eluent in this case, a mixture of hydrochloric acid and 1-butanol having a volume ratio of 1 to 12M, preferably 2 to 10M, in a volume ratio of 1 to 5 to 1 to 10 is used. The second group of noble metals, that is, gold, platinum, iridium and ruthenium, are eluted by the treatment in the step (d), and these are fractionated and collected in the same manner as in the step (c).

  Coexisting base metals having low affinity with cellulose, such as zinc, iron and copper, are removed through the cellulose column in the step (c). In addition, those having high affinity with cellulose, such as chromium, nickel, manganese and lead, are adsorbed to the cellulose column together with the noble metal. Since they exhibit different behavior, they can be easily separated in these steps.

Hereinafter, the difference in behavior of this noble metal and base metal with respect to cellulose will be described using a model solution containing rhodium, manganese, copper and iron.
After adding aqua regia to a mixture of rhodium, manganese, copper and iron and dissolving, it is heated and concentrated to remove nitric acid. Since this concentration causes rhodium chloride crystals to precipitate, concentrated hydrochloric acid is added to this and dissolved completely. Since a part of rhodium chloride is reduced by this treatment, an oxidizing agent such as chlorine gas or sodium perchlorate is added and completely oxidized to obtain 0.166 g of rhodium as a chloride, 0.345 g of manganese, A hydrochloric acid solution containing 1.635 g of copper and 1.493 g of iron, 0.023 g of chromium, 0.028 g of nickel and 0.026 g of lead is prepared. Next, 2-propanone and cellulose powder are added to this hydrochloric acid solution, and the mixture is stirred at room temperature to adsorb all the metal ions in the solution to cellulose, followed by filtration. The filtration residue is washed well with 2-propanone. The adsorption and filtration operations on cellulose are performed in an inert gas atmosphere, for example, a nitrogen atmosphere.

  Thus, when the cellulose which adsorb | sucked each metal ion was atomic absorption-analyzed and the recovery rate was calculated | required, rhodium 89.0 mass%, manganese 96.0 mass%, copper 28.0 mass%, iron 0 It was 0.5 mass%, chromium 83.0 mass%, nickel 99.0 mass%, and lead 99.0 mass%.

Subsequently, rhodium is separated and recovered as rhodium chloride by desorption using water or dilute hydrochloric acid. At this time, iron and copper are removed to a considerable extent, but other base metals remain together with rhodium. Base metals other than rhodium mixed in the eluent can be separated from rhodium in the step (c).

Next, an embodiment for continuously carrying out the method of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is an explanatory view showing an example of an apparatus suitable for carrying out the method of the present invention, which is a standing column 1, a liquid injection pipe 2 connected to the top thereof, and a liquid extraction connected to the bottom thereof. It consists of a tube 3.

  The column 1 contains a cellulose powder packed bed 4 and a filter 5 for fixing it, and a liquid injection tube 2 is connected to a noble metal-containing hydrochloric acid solution container (not shown) and a developing / eluent via a switching valve 6. It communicates with the container 8. On the other hand, the liquid take-out pipe 3 communicates with a plurality of distribution receptacles 10 through an electromagnetic switching valve 9. A detector 11 is disposed between the column bottom of the liquid extraction pipe 3 and the electromagnetic switching valve 9, and the switching valve is operated in conjunction with the detection result.

  In order to carry out the method of the present invention, the switching valve 6 is first operated to introduce a noble metal-containing hydrochloric acid solution from the top of the column 1 from a noble metal-containing hydrochloric acid solution container (not shown), and this hydrochloric acid solution is passed through the cellulose packed bed 4. . Then, when the hydrochloric acid solution passes through the column in this way, the noble metal chloride in the hydrochloric acid solution is adsorbed on the cellulose.

  Next, when the changeover valve 6 is switched to introduce the first development, eluent, that is, a mixture of hydrochloric acid and 2-propanone, the precious metal chloride is a fraction in which components A, B, C and D are mixed, and an E fraction. And the F fraction. Furthermore, when the first development and eluent are introduced and kept flowing down, the fractions containing A, B, C and D of the first group of precious metals, the E fraction and the F fraction flow out from the bottom of the column. It is received by the receiver 10. When the metal component in the liquid is detected by the detector 11, the information is transmitted to a switching mechanism (not shown) of the electromagnetic switching valve 9 and the switching valve is activated. , The flow path is switched to another distribution receptacle.

  In this way, when all of the first group of precious metals are separated and recovered, the development, the development into the eluent container 8, the second development from the eluent supply pipe 7, the eluent, that is, a mixture of hydrochloric acid and 1-butanol. Supply and continue to expand again, and separate and recover the second precious metal group A, B, C, D. In this way, separation and recovery of the noble metals A, B, C, D, E, and F contained in the hydrochloric acid solution can be performed.

The elution rate during this development can be fast enough for each precious metal-containing fraction to be completely separated, thus increasing the purity of the individual precious metals contained in each fraction, and thus A high-purity noble metal can be obtained. In this way, 2-propanone and 1-butanol in the used eluent, eluent, ie hydrochloric acid and 2-propanone mixture and hydrochloric acid and 1-butanol mixture, are recovered and purified by distillation. Can be reused. Cellulose is partly changed to glucose by hydrochloric acid, but it can be reused after washing it with water to remove it.
In addition, the method of the present invention does not need to be treated under heating unlike conventional methods, and any of them can be operated at room temperature.

The method of the present invention has the following advantages.
(1) The operation is simple.
(2) The adsorbent, the developing agent, and the eluent used are all inexpensive and readily available.
(3) The used cellulose, 2-propanone and 1-butanol can be purified and reused.
(4) Low energy consumption.
(5) Mass processing by automation is possible.
(6) Since 2-propanone and 1-butanol are easy to mix with water, it is easy to prevent fire.
(7) There is no risk of dioxin generation because no combustion treatment is performed to recover the noble metal.
Therefore, it is suitable as an industrial noble metal recovery method.

  Next, the best mode for carrying out the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Reference examples Rhodium (III) chloride tetrahydrate 0.166 g, manganese (II) 0.345 g, copper (II) chloride 1.85 g, iron (III) chloride 1.493 g, chromium (II) chloride 0.023 g Then, 0.028 g of nickel (II) chloride and 0.026 g of lead (II) chloride were dissolved in 1000 ml of 6M hydrochloric acid to prepare a model solution.
Next, 10 g of cellulose powder (trade name “KC Frog”, manufactured by Nippon Paper Chemical Co., Ltd.) and 50 g of 2-propanone are added to this hydrochloric acid solution, and the mixture is stirred for 4 hours at room temperature in a nitrogen atmosphere. Washed 3 times with 20 g of 2-propanone.
Next, the metal chloride adsorbed on the cellulose thus obtained was quantitatively analyzed using an atomic absorption spectrometer (manufactured by Shimadzu Corporation, product name “AA-6400F”). The results are shown in Table 1.

  As can be seen from this table, the noble metals Rh and the base metals Mn, Cr, Ni, and Pb are well adsorbed on cellulose, but Cu is hardly adsorbed and Fe is hardly adsorbed.

A solution containing Ru 6.3 g, Rh 1.6 g, Pd 7.4 g, Ir 2.5 g, Pt 3.0 g and Au 6.4 g in terms of chloride was prepared as a sample in 100 g of hydrochloric acid having a concentration of 6M.
100 mg of the sample was passed through a column chromatograph tube prepared by filling a glass tube having an inner diameter of 10 mm and a length of 500 mm with the same cellulose 13 g used in the reference example, and the noble metal was adsorbed on the cellulose.
Then, using the first development, eluent (mixture of 6M-hydrochloric acid 50 ml and 2-propanone 150 ml) and the second development, eluent (6M-hydrochloric acid 150 ml saturated with 1-butanol) under normal pressure at 25 ° C. , Each precious metal was separated and recovered at a development rate of 0.5 ml / min. Table 2 shows the recovery rate and purity of each noble metal recovered in this manner.

The parentheses in the purity column indicate other precious metals that accompany it.
As can be seen from this table, individual noble metals can be separated and recovered with high purity from a material containing a plurality of noble metals.

  About the rhodium containing hydrochloric acid solution used by the reference example, the process similar to Example 1 was performed, and the base metal in the rhodium isolate | separated and collect | recovered was quantitatively analyzed like Example 1. FIG. The results are shown in Table 3.

  As can be seen from this table, according to the method of the present invention, the coexisting base metal can be completely removed.

  The method of the present invention can be suitably used when collecting a noble metal from a precious metal ore or when collecting a noble metal from a waste containing a noble metal such as a used electronic component or a denture material.

Explanatory drawing which shows an example of an apparatus suitable for enforcing the method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Column 2 Liquid injection pipe 3 Liquid extraction pipe 4 Cellulose powder packed layer 5 Filter 6 Switching valve 7 Deployment, eluent supply pipe 8 Deployment, eluent container 9 Electromagnetic switching valve 10 Receiving receiver 11 Detector

Claims (6)

A method for separating and recovering noble metals, comprising the following steps (a) to (d), wherein each noble metal is separated and isolated with high purity from a material containing a plurality of noble metals and base metals.
(A) a step of dissolving the material in hydrochloric acid;
(B) passing the hydrochloric acid solution obtained in step (a) through a cellulose column and adsorbing a noble metal;
(C) a step of separating and recovering noble metals belonging to the first group by using a mixture of hydrochloric acid and 2-propanone as a developing and eluent, and (ii) hydrochloric acid and 1-butanol; A step of separating and recovering precious metals belonging to the second group using the mixture of   The method for separating and recovering a noble metal according to claim 1, wherein the step (a) is carried out using hydrochloric acid and chlorine.   The method for separating and recovering a noble metal according to claim 1, wherein the step (a) is performed using aqua regia.   The method for separating and recovering a noble metal according to any one of claims 1 to 3, wherein the noble metal belonging to the first group in step (c) is at least one selected from rhodium and palladium.   The method for separating and recovering a noble metal according to any one of claims 1 to 4, wherein the noble metal belonging to the second group in step (d) is at least one selected from gold, platinum, iridium and ruthenium. The method for separating and recovering a noble metal according to any one of claims 1 to 5, wherein the used cellulose column is washed with water, and 2-propanone and 1-butanol are purified by distillation and reused.

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