JP2005002414A - Method of recovering noble metal in solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of recovering noble metals in a solution by which particularly expensive platinum can efficiently be recovered in such a manner that it is separated from the other noble metals. <P>SOLUTION: An adsorption stage wherein a solution comprising noble metal elements is contacted with a chelating material to allow noble metals in the solution to be adsorbed; and a first elution stage where the chelating material with the noble metals adsorbed in the adsorption stage is contacted with a platinum elution liquid comprising perchlorate, so that the platinum in the noble metals adsorbed on the chelating material is eluted into the platinum elution liquid are performed to recover the platinum into the platinum elution liquid. Further, a second elution stage wherein the chelating material after the first elution stage is contacted with a metal elution liquid to elute the noble metals into the metal elution liquid is performed, so that the noble metals other than the platinum are recovered into the metal elution liquid. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for recovering a noble metal in a solution, and more particularly to a method for efficiently separating and recovering platinum from a plurality of noble metals such as platinum, palladium, and gold contained in a solution.
[0002]
[Prior art]
Precious metals such as gold, platinum and silver are used as decorative products because of their excellent corrosion resistance and gloss, and in recent years, their use as catalysts has also expanded. Since these noble metals are valuable resources, it is desirable to collect and reuse these noble metals from waste or liquid waste. For this reason, conventionally, techniques for recovering noble metals from wastes and waste liquids in various states have been proposed. For example, it has been proposed to recover noble metal by electrolysis from a waste liquid containing a high concentration of noble metal and to recover the noble metal from a waste liquid containing a low concentration of noble metal using a chelate ion exchange resin (for example, patents). Reference 1).
[0003]
[Patent Document 1]
JP-A-2001-279343
[Problems to be solved by the invention]
In addition, a specific noble metal is also separated and recovered from a solution containing a plurality of noble metals, but in any case, it requires a lot of labor, and the noble metal content in the solution is about several tens of ppm. In that case, there was a big problem with the recovery cost.
[0005]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for recovering a noble metal in a solution that can separate and recover an expensive platinum from other noble metals efficiently when recovering the noble metal in the solution.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a method for recovering a noble metal in a solution according to the present invention is a method for recovering a noble metal from a solution containing a noble metal element, wherein the solution is brought into contact with a chelating material to convert the noble metal in the solution to the chelating material. An adsorption process for adsorbing the precious metal in the adsorption process, and contacting the chelating material adsorbed with the precious metal in the adsorption process with a platinum eluent containing perchlorate so that platinum in the precious metal adsorbed on the chelating material is contained in the platinum eluent. And a first elution step for elution.
[0007]
Furthermore, the method for recovering a noble metal in the solution of the present invention includes a second elution step in which the chelating material that has finished the first elution step is brought into contact with a metal eluent to elute the noble metal into the metal eluent. It is characterized by. Further, performing a gold removal step of removing gold elements in the solution from the solution before the adsorption step, and further, the metal eluent is any one of thiocyanate, thiourea, mineral acid and dilute aqua regia. It is at least one, and the chelating material has at least one chelate functional group selected from the group having a functional group consisting of iminodiacetic acid, N-methyl-D-glucamine or polyethyleneimine.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic configuration diagram showing an example of a noble metal recovery device used for separating and recovering noble metal dissolved in a stock solution by platinum and noble metals other than platinum by the method of the present invention. The precious metal recovery apparatus is configured to separate a precious metal adsorption tank 11 that performs an adsorption process by bringing a stock solution into contact with a chelate material, and a chelate material that is mixed in the precious metal adsorption tank 11 and a stock solution (treatment liquid). A separation tank 12, a first elution tank 13 that performs a first elution step by bringing the chelate material separated in the first separation tank 12 into contact with a platinum eluent containing perchlorate, and the first elution tank 13 A second separation tank 14 for separating the chelate material after the platinum is eluted from the platinum eluent, and the chelate material separated in the second separation tank 14 is brought into contact with a metal eluent to perform a second elution step. A second elution tank 15 to be performed, and a third separation tank 16 for separating the chelate material after the precious metal is eluted in the second elution tank 15 and the metal eluent are provided.
[0009]
The noble metal adsorption tank 11, the first elution tank 13 and the second elution tank 15 use a complete mixing tank having a stirrer, but the contact method between the chelating material and each liquid is arbitrary, and a filling cylinder is used. Thus, it can be carried out in a downward or upward flow. The separation tanks 12, 14, and 16 that perform solid-liquid separation can use any solid-liquid separation means as long as the chelating material can be separated from each liquid. For example, filters, membrane separation, centrifugation, and the like can be used. These can be used, and these can also be used in combination. Further, this solid-liquid separation is performed by combining an appropriate solid-liquid separation means in the noble metal adsorption tank 11, the first elution tank 13, and the second elution tank 15, so that the adsorption tank and the It can also be carried out in an elution tank.
[0010]
As the chelating material used for recovering the noble metal, a chelating material having an ability to adsorb at least the noble metal contained in the stock solution, particularly platinum, is used. As this chelating material, various materials can be used depending on conditions such as the properties of the stock solution and the concentration of the noble metal. At least the chelating functional group introduced is iminodiacetic acid, N-methyl-D-glucamine, or polyethyleneimine. It preferably has at least one chelate functional group selected from the group having a functional group consisting of As a base material into which a chelate functional group is introduced, a synthetic resin such as polystyrene or a natural fiber such as cellulose can be used. The shape of the chelating material may be any of powder, short fibers, thread breaks, granules and beads. In consideration of handling properties and adsorption capacity, fibrous materials are most suitable. As an example, those having a molecular structure described in JP-A No. 2000-169828 are suitable, and those using a natural fiber or regenerated fiber as a base material and having a chelate functional group introduced therein are particularly preferred.
[0011]
In the noble metal adsorption tank 11, a stock solution in which a noble metal is dissolved is introduced from the stock solution introduction path 21, and the chelate material is introduced from the chelate material introduction path 22, and an adsorption process is performed in which the stock solution and the chelate material are brought into contact with each other. . Although the pH in this adsorption step varies depending on conditions such as the properties of the stock solution and the type of chelating material, it is usually preferable to carry out in the range of pH 0 to 3, so that hydrochloric acid or water can be supplied from the pH adjuster injection path 23 as necessary. The adsorption step is performed by injecting a pH adjusting agent such as sodium oxide to adjust the pH of the liquid in the tank to a pH suitable for adsorption of the noble metal. In this adsorption step, when the stock solution containing the noble metal and the chelating material come into contact, the noble metal in the stock solution is adsorbed by the chelating material and removed from the stock solution.
[0012]
The mixture of the undiluted solution (treatment solution) and the chelating material that has finished the predetermined adsorption process in the noble metal adsorption tank 11 is sent from the noble metal adsorption tank 11 to the first separation tank 12, and the chelate material that adsorbs the noble metal in the adsorption process and The stock solution from which the precious metal has been removed (processing solution) is separated, the separated processing solution is led out from the processing solution outflow path 24, and the separated chelating material is sent from the first separation tank 12 to the first elution tank 13.
[0013]
In the first elution tank 13, a platinum eluent containing perchlorate is introduced from the platinum eluent introduction path 25, and a first elution step is performed in which the chelating material that has adsorbed a noble metal and the platinum eluent are brought into contact with each other. The platinum in the noble metal adsorbed on the chelating material is eluted in the platinum eluent. The concentration of the perchlorate in the platinum eluent varies depending on the type of chelating material and the amount of precious metal adsorbed. Usually, about 0.01 to 3M is appropriate. If the concentration is too low, the platinum is sufficient. It becomes difficult to elute, and even if the concentration is increased, the elution effect is hardly improved.
[0014]
A mixture composed of a platinum eluent in which platinum eluted from the chelate material in the first elution step of the first elution tank 13 is dissolved and a chelate material in a state where a precious metal other than platinum is adsorbed is removed from the first elution tank 13. It is sent to the second separation tank 14 and the platinum eluent and the chelating material are separated. The separated platinum eluent is led out from the platinum eluent outlet path 26 in a state where platinum is dissolved, and the separated chelating material is sent from the second separation tank 14 to the second elution tank 15.
[0015]
In the second elution tank 15, a metal eluent is introduced from the metal eluent introduction path 27, and a second elution step is performed in which the chelate material in a state where a precious metal other than platinum is adsorbed is brought into contact with the metal eluent. Precious metals other than platinum adsorbed on the material are eluted in the metal eluent. The metal eluent used in the second elution step may be selected from those capable of eluting metal from the chelate material according to the type and amount of metal (noble metal) adsorbed on the chelate material and the type of chelate material. However, usually, any of thiocyanate, thiourea, mineral acid and dilute aqua regia may be used, and these may be contacted with the chelating agent in an appropriate order to elute a plurality of metals separately. Is possible.
[0016]
The mixture of the metal eluent and the chelating material that has finished the second elution step in the second elution tank 15 is sent from the second elution tank 15 to the third separation tank 16 to dissolve the metal other than platinum. The eluent and the chelating material after the various metals adsorbed in the adsorption step are eluted are separated. The separated metal eluent is led out from the metal eluent lead-out path 28 in a state where various metals are dissolved, and the separated chelate material is led out to the chelate material circulation path 29 in a state where no metal is adsorbed, It circulates in the noble metal adsorption tank 11 through the chelate material introduction path 22 and is reused in the adsorption process.
[0017]
On the other hand, the platinum eluent led out to the platinum eluent lead-out path 26 is subjected to post-treatment according to the platinum concentration in the platinum eluent. For example, when the platinum concentration in the platinum eluent is high to some extent, Platinum can be recovered by electrolytic treatment. Further, the metal eluent led out to the metal eluent lead-out path 28 is also processed according to the type of the dissolved metal, and can be recovered in a state suitable for each metal.
[0018]
In addition, when recovering platinum through such a process, if the stock solution contains gold at a relatively high concentration, it is preferable to perform a pretreatment to remove the gold element in advance before performing the adsorption process. . That is, when perchlorate comes into contact with the gold adsorbed on the chelate material in the adsorption process, the gold element changes to solid gold, and is mixed and accumulated in the chelate material used in circulation. Since this solid gold moves little by little to the processing solution and eluent, the gold recovery rate decreases when mixed in the processing solution, and the platinum impurities recovered when mixed in the platinum eluent. It becomes. The removal of gold from the stock solution before the adsorption step can be performed by a generally known method, and can be easily performed by adjusting the pH, for example.
[0019]
【Example】
As a chelating material, Kirest Fiber GRY manufactured by Kirest Co., Ltd. was used, and while removing the noble metal from the solution containing a plurality of noble metal elements, an experiment was conducted for separating and collecting platinum. For the experimental stock solution, an aqueous solution in which 20 ppm each of gold, indium, gallium, palladium, rhodium and platinum were dissolved and adjusted to pH 1.0 was used as a noble metal element.
[0020]
An open column having an inner diameter of 6 mm was filled with about 1 g of a chelating material (Cyrest fiber GRY), and 1.2 liters of the stock solution was introduced into this column at a flow rate of about 100 ml / h to perform an adsorption step. At this time, the liquid flowing out from the column was analyzed with a plasma emission analyzer, and the concentration of each element was measured. The result is shown in FIG. FIG. 2 is a graph showing the relationship between the stock solution introduction amount and the concentration of each noble metal element in the derived solution, and the vertical axis represents the ratio of the measured concentration (C) to the initial concentration (C0) (concentration ratio: C / C0), and the horizontal axis represents the amount of stock solution introduced [ml].
[0021]
From this result, it can be seen that indium, gallium and rhodium pass through the column without being adsorbed on the chelate material. In addition, it can be seen that gold reached 300 ml, palladium reached 360 ml and reached the breakthrough point, and platinum reached 900 ml. The reason why the concentration after the breakthrough point of gold and palladium is equal to or higher than the initial concentration is that gold and palladium desorbed from the chelating material are included.
[0022]
Next, after washing the chelating material into which 50 ml of distilled water was introduced into the column, 200 ml of 1M sodium perchlorate aqueous solution (platinum eluent) was introduced into the column at about 110 ml / h to carry out the first elution step. The concentration of each element in the liquid flowing out from the column was measured. The result is shown in FIG. FIG. 3 is a graph showing the relationship between the amount of platinum eluent introduced and the concentration of each noble metal element in the derived liquid, wherein the vertical axis represents the concentration of each noble metal element [ppm], and the horizontal axis represents platinum elution. The amount of liquid introduced [ml].
[0023]
From this result, it can be seen that platinum adsorbed on the chelating material elutes in a 1M sodium perchlorate aqueous solution in a short time, and gold and palladium are hardly eluted. In the initial 20 ml of the platinum eluent flowing out from the column, the proportion of platinum in the noble metal component increased from 16.6% to 94.9%, indicating that the platinum was purified.
[0024]
【The invention's effect】
As described above, according to the method for recovering a noble metal in a solution of the present invention, when recovering a noble metal from a solution containing a trace amount of a noble metal element, particularly expensive platinum can be efficiently separated and recovered. .
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a noble metal recovery apparatus.
FIG. 2 is a diagram showing the relationship between the amount of the stock solution introduced in the adsorption step of the example and the concentration ratio of each noble metal element in the derived solution.
FIG. 3 is a graph showing the relationship between the amount of platinum eluent introduced and the concentration of each noble metal element in the derived liquid in the first elution step of the example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Precious metal adsorption tank, 12 ... 1st separation tank, 13 ... 1st elution tank, 14 ... 2nd separation tank, 15 ... 2nd elution tank, 16 ... 3rd separation tank, 21 ... Stock solution introduction path, 22 ... Chelate Material introduction path, 23... PH adjuster injection path, 24... Treatment liquid outflow path, 25... Platinum eluent introduction path, 26. 29 ... Chelating material circulation path

Claims (5)

In the method of recovering a noble metal from a solution containing a noble metal element, an adsorption step of bringing the solution into contact with a chelating material to adsorb the noble metal in the solution to the chelating material, and the chelating material that adsorbs the noble metal in the adsorption step A first elution step in which platinum in the noble metal adsorbed on the chelating material in contact with a platinum eluent containing perchlorate is eluted into the platinum eluent. Collection method. The precious metal in the solution according to claim 1, further comprising a second elution step of bringing the chelate material that has finished the first elution step into contact with a metal eluent to elute the precious metal into the metal eluent. Collection method. The method for recovering a noble metal in a solution according to claim 1 or 2, wherein a gold removing step for removing gold element in the solution from the solution is performed before the adsorption step. 3. The method for recovering a noble metal in a solution according to claim 2, wherein the metal eluent is at least one of thiocyanate, thiourea, mineral acid, and dilute aqua regia. The solution according to claim 1 or 2, wherein the chelating material has at least one chelating functional group selected from the group having a functional group consisting of iminodiacetic acid, N-methyl-D-glucamine, or polyethyleneimine. Method for recovering precious metals.

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