JPH0813053A - Refining method of rhodium - Google Patents

Abstract

PURPOSE:To efficiently separate and recover Rh with a high recovery rate and high refining efficiency by incorporating an oxidizing agent to an org. soln. of a hydrochloric acid contg. the Rh, heating the soln. and subjecting the soln. to a complex strengthening treatment, then diluting the soln. with pure water and immediately passing the soln. through a cation exchange resin. CONSTITUTION:The oxidizing agent, such as nitric acid or hydrogen peroxide, is incorporated to the acidic soln. of the hydrochloric acid contg. the Rh together with various kinds of impurities at 100 to 600ml per 1g Rh and the son. is subjected to the complex strengthening treatment involving a heat treatment for about 2 to 6 hours at 40 to 80 deg.C. As a result, the Rh in the soln. is converted to complex anions, such as [RhCl4]<->. This soln. is then diluted with the pure water to about pH 0 to 1.0 and thereafter the soln. is rapidly passed through the cation exchange resin while the Rh complex is in a non-equil. state. As a result, the platinum group metals contg. the Rh are adsorbed in nearly the whole amt. in the resin. Only the Rh is thereafter selectively desorbed from the resin by using a 6N hydrochloric acid, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for efficiently and simply purifying rhodium from an acidic hydrochloric acid solution containing rhodium along with various impurities.

[0002]

2. Description of the Related Art A conventional chemical precipitation method has been mainly used as a method for purifying rhodium from a solution containing rhodium together with a large amount of various impurity metals (Fe, Cu, Pb, Ni, Cr, etc.). Instead of the wet method, various methods using an ion exchange resin have recently been proposed to improve the recovery rate of rhodium. For example, JP-A-3-277731 and JP-A-3-277730 can be cited. In the former method, rhodium-containing aqueous solution in which chlorides of various metals are dissolved as impurities is first passed through a cation exchange resin to remove cation impurities such as base metal, and then heat treatment is performed after adjusting the acid concentration. It is a solution that is passed through an anion exchange resin to adsorb and remove anion impurities of noble metals other than rhodium, and the liquid that flows out becomes a purified solution of rhodium. Further, the latter method is the same as the former method except that a resin impregnated with an organic solvent having an anion exchange group is used instead of the anion exchange resin.

However, in the conventional method as described above, when the amount of impurities is large, the cation exchange resin cannot completely remove the cation impurities such as base metal, and rhodium is partially adsorbed on the cation exchange resin. Furthermore, since it is also adsorbed on the anion exchange resin, a separate treatment is required for each. In addition, since the effluent is finally a rhodium purified liquid, it is not possible to deal with impurities that could not be adsorbed on the resin, and there is a problem that the purification rate and the recovery rate are insufficient.

The present invention is completely different from the conventional method in which only an anion exchange resin is used, and a platinum group metal containing rhodium is adsorbed to the anion exchange resin, and then rhodium can be selectively separated therefrom with a high recovery rate. It provides an epoch-making method.

[0005]

The present invention provides a method for purifying rhodium from a hydrochloric acid acidic solution containing rhodium together with various impurities, and a complex strengthening treatment in which an oxidizing agent is added to the hydrochloric acid acidic solution for heat treatment. Characterized by diluting the solution with pure water, immediately passing this solution through an anion exchange resin to adsorb the platinum group metal to the resin, and then selectively separating only rhodium from the resin In this way, the above problems are solved.

[0006]

In the present invention, rhodium is easily adsorbed to the anion exchange resin by subjecting the acidic hydrochloric acid solution containing rhodium together with impurities to complex strengthening treatment, and the rhodium-containing platinum is passed through the resin immediately after dilution. Almost all of the group metal can be adsorbed on the anion exchange resin, and the recovery rate of rhodium is dramatically improved as compared with the conventional method.

Hereinafter, the present invention will be described in more detail. The solution targeted by the present invention is, for example, a hydrochloric acid acidic solution such as a collector metal. In a hydrochloric acid solution, rhodium easily forms a chlorine complex ion according to the minus monovalent chloride ion concentration as shown in the following formulas 1 to 6.

[0008]

(Equation 1)

(Equation 2)

(Equation 3)

(Equation 4)

[Formula 5]

[Formula 6]

In the acidic solution of hydrochloric acid, a part of rhodium is dissolved in the form of cation complex [RhCl ₂ ] (plus monovalent ion) and [RhCl ₃ ] (charge of 0), and they are anion exchanged. Does not stick to resin. Only the negative ion number of the Rh hydrochloric acid complex ion is adsorbed on the anion exchange resin. That is, [RHCl ₄ ] (minus monovalent), [RhCl ₅ ] (minus divalent), [R
hCl ₆ ] (minus trivalent).

When the selectivity of Rh ion chlorine complex formation and resin adsorption of Rh chlorine complex is regarded as the result of competitive reaction, R
When h is complexed, h is more likely to form a complex with more chlorine as the surrounding chlorine ion concentration is higher. In addition, when adsorbing to a resin, the lower the concentration of free chloride ions around the part that does not participate in complex formation, the easier it is to adsorb to the resin, and the greater the number of chlorine ions in the Rh complex due to the difference in the charge of the complex, the greater the resin adsorption. It is considered easy to do.

Therefore, in the present invention, Rh is added to an oxidizing agent such as nitric acid or hydrogen peroxide in a relatively concentrated hydrochloric acid solution and heat-treated to obtain a complex anion ([RHCl ₄ ] (minus monovalent)). , [RhCl ₅ ] (minus divalent), [R
hCl ₆ ] (minus trivalent)), diluted with pure water to reduce the concentration of free chlorine ions, and then immediately ion-exchanged.

Regarding the acid concentration of the base solution for carrying out complex anionization, when the hydrochloric acid concentration is lower than 2N, the initial complexation rate (the ratio of chlorine complex anions from the beginning) is low and the free chlorine concentration is high. Since it also becomes low, the effect of the addition of the oxidizing agent does not increase, which is not preferable. Further, the Rh concentration in the original solution is preferably 10 g / l or less.

In the present invention, it is not the hydrogen ion concentration that affects the reaction but the chlorine ion concentration. However, since it is difficult to measure the chlorine ion concentration quickly, it is convenient to measure the pH with a pH meter. It is measured and used as a criterion for the chlorine ion concentration.

The amount of the oxidizing agent added to the hydrochloric acid acidic solution is
100 g of 62% nitric acid for 1 gram of Rh in the liquid
˜600 ml, more preferably 400 ml, and the same applies when hydrogen peroxide is used as the oxidant. If the amount of nitric acid added exceeds 600 ml, the amount of pure water at the time of dilution increases, which is not desirable. The heating temperature is 40 to 80 ° C., and the heating time is 2 hours to 6 hours, preferably 60 ° C. for 4 hours. If the heating temperature exceeds 80 ° C, the material of the equipment will be expensive due to the nature of the solution, and it is assumed that one batch process will be carried out in two-side operation per day. It is not preferable because it may not be processed depending on the day.

After the heat treatment, it is diluted with pure water, and the pH of the liquid is preferably adjusted to 0 to 1.0. When the pH is 0 or less, Rh is less likely to be adsorbed on the resin, and when the pH is 1.0 or more, the amount of liquid after dilution becomes enormous, which is not realistic. Immediately after diluting with pure water to reduce the concentration of free chlorine ions, the Rh complex having a large amount of chlorine ions is dissolved in a non-equilibrium state, and chlorine is released over time to reach an equilibrium state. To do. Therefore, it is necessary to quickly pass the resin through the resin after dilution. The resin is preferably passed within 24 hours, more preferably within 12 hours.

By passing the solution through the anion exchange resin, almost all the platinum group metal containing Rh is adsorbed on the anion exchange resin. Generally, in the case of a hydrochloric acid acidic solution, when the acid concentration is high, the chloride ion is more easily adsorbed to the resin than the Rh complex anion because of the difference in distribution coefficient. As for the relationship between the distribution ratio of Rh to the anion exchange resin and the HCl concentration, the Kraus table is well known, and according to it, the adsorption distribution ratio of Rh to the resin is 4
It becomes 0 at around 6 regulations. Therefore, Rh adsorbed on the anion exchange resin can be released from the resin using 4 to 6N hydrochloric acid. That is, when Rh is adsorbed on the resin and 4 to 6N hydrochloric acid is passed through, R
Free chlorine ions other than those forming h complex ions increase. As a result of the competitive reaction, the chlorine complex anion of Rh leaves the resin and instead the chlorine ion adsorbs to the resin.
In practice, the concentration of hydrochloric acid passed through the resin can be 2 to 8 N, but preferably it is 4 to 6 N as described above. The amount of hydrochloric acid to be passed is set to be 3 to 4 times the amount of resin in the column.

As the anion exchange resin usable in the present invention, any strongly basic anion exchange resin can be used, for example, Dowex SBR (trade name, manufactured by Dow Chemical Co.), Amberlite IR-120B ( Organo, trade name), DIAION SA-10 (manufactured by Mitsubishi Kasei Co., Ltd.), etc., but care must be taken because the Rh adsorption amount per unit resin varies depending on the particle size of the resin.

[0018]

Example 1 An example of purifying Rh contained therein by using a commercially available hydrochloric acid acidic solution in which a collector metal is dissolved (impurity grade in the solution is shown in Table 1) is shown. In the liquid, as shown in Table 1, a large amount of cationic impurities (Cu, Cr, N
i)) was dissolved and the Rh concentration was 329 mg / l. After heating 100 ml of this hydrochloric acid acidic solution to 60 ° C., 10 ml of 62% nitric acid was added, and the mixture was kept at 60 ° C. for 4 hours while stirring. Then, the solution was cooled and diluted with pure water to pH 0, and passed through the resin at SV = 2. As the anion exchange resin, used was one in which 200 ml of Diaion SA10AS was packed in a test column, and hydrochloric acid adjusted to pH 0 was passed through until the pH of the effluent became 0. After passing the sample solution, push out with 400 ml of pure water to let the sample solution in the column flow out of the column, and then pass 6N hydrochloric acid in an amount 3 times the resin amount to desorb Rh adsorbed on the resin. Let At that time, the desorption rate of Rh from the resin is 1 regardless of the adsorption rate to the resin.
At 00%, all Rh adsorbed was desorbed. The Rh net amount in the total effluent was calculated from the analytical value, and the recovery rate of Rh was calculated. The same test was performed 3 times, and the average value of the Rh recovery rates was calculated to be 98.7%.

[0019]

[Table 1]

[0020]

Example 2 Example 1 was repeated except that the same amount of hydrogen peroxide (35%) was added instead of nitric acid under the same conditions as in Example 1.
Rh was purified in the same manner as in. As a result, the average recovery rate was 96.3%.

[0021]

[Example 3] Rh was purified in the same manner as in Example 1 except that the heat treatment was carried out at 40 ° C. as a result,
The average recovery rate of Rh was 88.4%.

[0022]

Example 4 Rh was purified in the same manner as in Example 1 except that the pH after dilution with pure water was 1.0. as a result,
The recovery rate of Rh was 92.3%.

[0023]

COMPARATIVE EXAMPLE 1 Same as Example 1, except that no oxidizing agent was added and only heat treatment was performed. Other conditions are Example 1
And tested in the same manner. As a result, the average recovery rate of Rh was 69.3%.

[0024]

Comparative Example 2 Under the same conditions as in Example 1, no oxidizing agent was added, no heat treatment was performed, and only pure water was diluted and tested. Other conditions are the same as those in the first embodiment. as a result,
The average recovery rate of Rh was 51.6%.

[0025]

Comparative Example 3 100 ml of the same original solution as in Example 1 was passed through the anion-exchange resin as it was without adding an oxidizing agent or diluting it. Other conditions were tested in the same manner as in Example 1.
As a result, the average recovery rate of Rh was 34.1%.

The results of the above Examples and Comparative Examples are summarized in Table 2.

[0027]

[Table 2]

[0028]

According to the present invention as described above, Rh can be efficiently recovered by using only an anion exchange resin, the whole process is simple, and the number of treatment days is short.
Even when a large amount of cations such as base metals are contained, the cations are not adsorbed, and only anions such as platinum group metals are adsorbed on the anion exchange resin, and then only Rh is selectively separated and recovered. Therefore, it has an unprecedented unique effect that Rh with a high purification rate can be obtained with high efficiency, and is extremely useful in the art.

Claims (1)

[Claims] 1. A method for purifying rhodium from a hydrochloric acid acidic solution containing rhodium together with various impurities, in which a oxidizing agent is added to the hydrochloric acid acidic solution to carry out a heat treatment for complex strengthening, and then the solution is diluted with pure water. Then, the solution is immediately passed through an anion exchange resin so that the platinum group metal is adsorbed on the resin, and then only rhodium is selectively separated from the resin.