JP3113762B2 - Separation method of copper and lead from precious metal solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating copper (Cu) and lead (Pb) from a solution in which a noble metal such as a noble metal waste liquid is dissolved.

[0002]

2. Description of the Related Art Conventionally, this type of separation method includes C
When the contents of u and Pb are large compared to the noble metal, the noble metal and the aqua regia or hydrochloric acid / chlorine solution of Cu and Pb are completely changed to chloride, and then zinc (Zn) is immediately introduced and only the noble metal is added. Reduced and separated from Cu and Pb as black powder, or
When the contents of Cu and Pb are smaller than the noble metal, most of the noble metal is dropped by ammonium chloride (NH ₄ Cl), separated as a salt of (NH ₄ ) ₂ MCl ₆ , and the remaining liquid is reduced by Zn. A method of recovering by using is known (see “Platinum Family and Industrial Use”, published by Sangyo Tosho Co., Ltd. on December 20, 1956, page 218).

[0003]

However, in the conventional separation method, when a noble metal is separated from a solution containing a large amount of Cu and Pb, when the noble metal is reduced with Zn, the noble metal precipitates as a black powder. , And Pb are also precipitated at the same time, so that Zn reduction is performed again to reduce the contents of Cu and Pb, dropped by NH ₄ Cl, and the noble metal is reduced to (NH ₄ ).
₂ Separation as a salt of MCl ₆ , then redissolution and wet purification, there is a problem that the number of steps is increased. Also, Zn
Since noble Cu and Pb cannot be completely separated from the noble metal by Zn reduction, the content of Cu and Pb is larger than the solution separated by electrolysis even in the purification step. It is necessary to repeat the purification a few times.
Furthermore, there is a problem that the noble metal remains in the residual liquid after the Zn reduction. Therefore, the present invention reduces the number of processes and
It is an object of the present invention to provide a method for separating copper and lead from a noble metal solution which can shorten a work-in-progress period and have a high purity with a small loss of noble metal.

[0004]

In order to solve the above-mentioned problems, a method for separating copper and lead from a noble metal solution according to the present invention is characterized in that a noble metal anode is placed in an anode chamber of an electrolytic cell in which an anode and a cathode are separated by a cation exchange membrane. It is characterized in that an aqua regia or a hydrochloric acid / chlorine solution containing an ionic complex and copper and lead is put therein, and an electrolytic solution containing a metal cation which is more base than hydrogen and is trivalent or more than hydrogen is put in a cathode chamber to perform electrolysis. The noble metals are platinum (Pt), palladium (P
d), one or more of rhodium (Rh), osmium (Os), iridium (Ir), ruthenium (Ru) and gold (Au). Also, aqua regia or hydrochloric acid containing the noble metal anion complex and copper or lead /
The chlorine solution is characterized by being concentrated by evaporation and then diluted with water to adjust the pH to 0.5 to 2.

[0005]

In the above means, since the noble metal is an anion complex, it stops in the anode compartment, while Cu and Pb are present as cations and move through the cation exchange membrane to the cathode compartment. In addition, the pH of aqua regia or a hydrochloric acid / chlorine solution containing a noble metal anion complex and copper or lead is adjusted to 0.5 to 2,
Furthermore, the reason why alkali such as sodium hydroxide is not used for this adjustment is that the concentration of ions such as H ⁺ and Na ^{+, which} have a higher transport number than that of impurities such as Cu and Pb, is sufficiently reduced to reduce the concentration of impurities such as noble metal anion complex. This is to promote movement. As a cation contained in the electrolyte solution to be put into the anode chamber, a metal cation which is more base than H ⁺ and has a valence of 3 or more is used because the ion exchange membrane is proactively made of a metal cation having a valence of 2 or less. The trivalent or higher metal cations that pass therethrough are very difficult to pass through the ion exchange membrane.
(However, if electrolysis is continued for a long time, metal cations having a valency of 3 or more may pass or clogging of the exchange membrane may occur.) Electrolysis is performed at a low current density of 1 to 4 A / acm ² .

[0006]

Hereinafter, examples of the present invention will be described together with comparative examples. Examples 1 to 7 First, as shown in Tables 1 and 2, an anionic complex of a noble metal (one or more of Pt, Pd and Rh) and C
1.4 L of each aqua regia containing u and Pb was concentrated to 50 L by evaporation to 0.7 L. Precious metals and C in each aqua regia before and after concentration
The concentrations of u and Pb were as shown in Tables 1 and 2, respectively. Then, each aqua regia concentrated to 0.7 l was purified with pure water to pH
0.5-1.5 range (approximately 3.7 times), specifically, 0.7l
Diluted to 2.5 l and adjusted to about pH 1.0. Precious metals and Cu, Pb in each aqua regia diluted to 2.5 l as described above
Were as shown in Tables 1 and 2, respectively.

Next, each aqua regia diluted to 2.5 liters is
An anode (Ti-Pt plate) and a cathode (Ti plate) are placed in an anode compartment of an electrolytic cell partitioned by a cation exchange membrane (for example, Selemion CMV or Nafion 324), while a cathode compartment which is lower than H ^{+ and} has a valence of 3 or more. AlCl as electrolyte containing metal cations
₃ Add 150 g / l solution and check the current density of the anode in Tables 1 and 2.
The electrolysis was performed for 24 hours as shown in (1). The concentrations of the noble metals and Cu and Pb in each solution in the anode chamber after electrolysis and the purity of the noble metal solutions are as shown in Tables 1 and 2, respectively. In each cathode plate, Cu, Pb and trace amounts of noble metals are contained. The trace amount of the noble metal was decomposed by electrodeposition, and the ratio of the trace amount of the noble metal to the noble metal in the anode chamber was as shown in Tables 1 and 2, respectively. The current density of the anode is preferably set in the ranges shown in Tables 1 and 2, respectively. If the anode congestion is below the lower limit, H
^While the generation of ² is large and metallization occurs in the anode chamber, if the upper limit is exceeded, the leakage of the precious metal increases significantly.

[0008]

[Table 1]

[0009]

[Table 2]

Comparative Examples 1 to 7 For comparison, as shown in Tables 3 and 4, first, Examples 1 to 7
Noble metal anion complex similar to 7 and each aqua regia containing Cu and Pb were reduced with Zn to precipitate a black powder of the noble metal. At the time of this reduction, the noble metal in the proportions shown in Tables 3 and 4
n and remained in the reduced solution, and Cu and Pb entered into the precipitate at the ratios shown in Tables 3 and 4 by adsorption and entrainment of the solution.
Subsequently, the precipitate was filtered, and unnecessary salts were removed by washing. Thereafter, the filtrate was calcined to remove unnecessary salts. As a result, about 1% could be removed. During this firing, a slight loss of the noble metal occurred. Next, when each fired product was dissolved in aqua regia or hydrochloric acid / chlorine solution, the purity of the noble metal solution became as shown in Tables 3 and 4, respectively. On the other hand, the noble metal remained in the Zn reduction waste liquid as a loss as shown in Tables 3 and 4, and it was difficult to remove the noble metal from the noble metal (the Zn concentration was as high as about 80 g / l). ). That is, in order to separate Cu from the waste liquid of Zn reduction, Cu is precipitated by hydroxide reduction by sodium nitrite reduction and separated, but at this time, 5 to 10% of the noble metal enters the hydroxide by adsorption or the like. is there.

[0011]

[Table 3]

[0012]

[Table 4]

As can be seen from Tables 1 to 4, Example 1
According to Nos. To 7, it can be seen that a high-purity noble metal solution can be obtained by reducing the loss of the noble metal, and the number of steps can be reduced and the in-process time can be shortened.

[0014]

As described above, according to the method for separating copper and lead from a noble metal solution of the present invention, since the noble metal is an anion complex, it stops in the anode compartment, while Cu and Pb are converted as cations. Since it is present, it passes through the cation exchange membrane and moves to the cathode compartment, so that noble metal loss can be reduced and a highly pure noble metal solution can be obtained as compared with the conventional separation method. Can be significantly improved, the number of steps can be reduced, and the in-process period can be shortened.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Isamu Kawano 2015-7 Takaya, Ichikawa-shi, Chiba Investigator, Tanaka Kikinzoku Kogyo Co., Ltd. Ichikawa Plant Kyoko Arita (56) References JP-A-61-246395 (JP, A) JP-A-60-128279 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C25C 1/00-7/08

Claims (3)

(57) [Claims] 1. A noble metal anion is charged with a complex and an aqua regia or a hydrochloric acid / chlorine solution containing copper and lead in an anode chamber of an electrolytic cell in which an anode and a cathode are separated by a cation exchange membrane. 3. A method for separating copper and lead from a noble metal solution, wherein an electrolyte solution containing a metal cation having a valence of 3 or more is added to perform electrolysis. 2. The method according to claim 1, wherein the noble metal is one or more of platinum, palladium, rhodium, osmium, iridium, ruthenium and gold. Separation method. 3. The aqua regia or hydrochloric acid / chlorine solution containing the noble metal anion complex and copper and lead is concentrated by evaporation and then diluted with water to adjust the pH to 0.5 to 2. The method for separating copper and lead from a noble metal solution according to claim 1 or 2.