JP3437506B2 - How to recover high purity platinum - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for obtaining high-purity platinum. More specifically, it relates to a method of separating palladium from an aqueous solution containing palladium and platinum to obtain highly pure platinum. Furthermore, the present invention relates to a method for obtaining high-purity platinum by separating palladium from the platinum-containing extract obtained in the smelting step.

[0002]

2. Description of the Related Art Platinum obtained in a smelting process contains tellurium,
Impurities such as palladium and iron are contained, and sponge platinum obtained from them has hitherto not been able to satisfy the standard. Above all, it is difficult to separate palladium from platinum because of its close chemical properties with platinum.

A solvent extraction method is known as a method for separating platinum and palladium (Japanese Patent Laid-Open No. 25352/1993).
No. 4, Japanese Patent Laid-Open No. 11-229052).
JP-A-3-253524 describes a solvent extraction method using a dialkylethane as an extractant.
In this method, it is suggested that palladium and platinum can be separated by adjusting the concentration of hydrochloric acid and the extraction time, but normally, palladium and platinum are simultaneously extracted and recovered. Japanese Patent Application Laid-Open No. 11-229052 discloses a nitric acid acidic solution containing platinum and palladium.
A method of separating palladium and platinum by extracting palladium with a oxime-based solvent and then contacting it with an octylamine-based solvent to extract platinum is described, but it requires two steps of extraction.

Allyl alcohol is added to a mixed hydrochloric acid acidic solution of platinum and palladium to reduce palladium to a metallic form, the filtrate after washing by filtration is made alkaline with sodium hydroxide, and formic acid is added to heat the platinum to the metal. Reduced to
There is also provided a method for separating platinum and palladium by filtering (Japanese Patent Laid-Open No. 6-287654), but the process is complicated.

Thus, at present, a satisfactory method for efficiently and easily separating palladium from a platinum-containing aqueous solution containing palladium has not been provided.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to efficiently separate palladium from an aqueous solution containing palladium and platinum and recover highly pure platinum. Another object is to provide a method for recovering high-purity platinum by separating palladium from a platinum-containing platinum extract obtained from the smelting step.

[0007]

[Means for Solving the Problems] On the other hand, the present applicant notices that dimethylglyoxime is used in a quantitative analysis method of palladium, and adds dimethylglyoxime to a gold electrolytic solution containing palladium. , A method for purifying a gold electrolytic solution in which a palladium complex is generated and precipitated to separate palladium (Japanese Patent Laid-Open No. 11-12778). The present inventors focused their attention on the fact that this precipitation method using dimethylglyoxime can be used in order to separate palladium in the platinum smelting process, and as a result of diligent research, dimethylglyoxime was added under specific conditions. By doing so, it was found that palladium can be separated with a high removal rate, and the present invention has been completed.

That is, according to the present invention, the pH of an aqueous solution containing platinum and palladium is adjusted to a value higher than 8 and then dimethylglyoxime is added to highly remove palladium from the aqueous solution containing platinum and palladium. It was found that the rate of separation and removal can be increased efficiently. further,
It was also found that palladium can be removed at a higher removal rate when the amount of dimethylglyoxime added is 2 or more in terms of molar ratio to the amount of palladium in the liquid. Also,
The present invention is more useful when the aqueous solution containing platinum and palladium is the aqueous solution obtained from the platinum extraction step in the smelting step. Furthermore, the present invention also provides a method for recovering highly pure platinum using the aqueous platinum solution from which palladium has been removed in this way.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to FIGS.
A description will be given according to the flowchart shown in FIG. FIG. 1 is a flowchart showing a step of recovering platinum (Pt step) from an extract containing palladium, platinum, etc. obtained from a copper smelting step or the like. FIG. 2 shows a step from the post-tributyl phosphate (TBP) back-extraction liquid (hereinafter referred to as a chloroplatinic acid solution) to crystallization of Pt in the Pt step as a palladium removal step (Pd removal step).

The outline of the depalladium step is as follows. First, the pH of the chloroplatinic acid solution is adjusted to neutralize, iron and the like are precipitated in the neutralizing step, and then dimethylglyoxime (DMG).
Is added to remove palladium.

The present inventors have now revealed that the pH of the neutralization step affects the Pd removal rate by the addition of DMG. When the pH of the neutralization step is 8 or less,
The effect of removing Pd is poor, and when the pH exceeds 8, the effect of removing Pd remarkably increases. In addition, the present inventors
It was also found that the addition amount of DMG affects Pd removal in the addition step. That is, when DMG is added in a molar ratio of 2 or more with respect to the amount of Pd in the liquid, the Pd removal rate is further increased.

The effects of the pH in the neutralization step and the amount of DMG added on the Pd removal rate will be described in detail below with reference to Examples 1 and 2.

Example 1 A chloroplatinic acid solution was adjusted to pH 1 with a NaOH solution.
After adjusting to, the mixture was filtered through 5C filter paper, and a part of the filtrate was used as a sample for analysis. 300 ml of this filtrate was collected, and NaO was added.
Immediately after adjusting the neutralization pH (5-10) with H solution to 1
It was filtered with a membrane filter of μ. 25 of this filtrate
0 ml was sampled and the molar ratio (Pd in the solution after adjusting DMG / pH) =
DMG was added so that the amount became 2, and the mixture was stirred for 1 hour, and then filtered through a 1 μ membrane filter again to measure the amount of filtrate and the amount of residue, which was used as a sample for analysis.

Table 1 shows the concentration of each component in the after-treatment liquid treated with each neutralized pH and after the addition of DMG.

[Table 1] Concentration in solution after neutralization and in solution after addition of DMG

Furthermore, the neutralization pH, the neutralized solution and DM
The relationship with the Pd and Pt concentrations in the liquid after addition of G is shown in FIG.

From Table 1 and FIG. 3, the Pd concentration is 55 to 12 if neutralized at a pH higher than 8 and then DMG is added.
It can be seen that it decreases from 5 mg / L to several mg / L. On the other hand, when DGM was added in the region lower than pH 8, the Pd concentration decreased only to about 21 mg / L.

[0016]

Example 2 To test the effect of DMG addition amount, p
H was set to 8.5, and the addition molar ratio of DMG (DMG / p
After the H adjustment, the same method as in Example 1 was repeated except that Pd) in the liquid was changed and analyzed. The results are shown in Table 2 and FIG.

[Table 2] DMG addition amount and Pd concentration Table 2 and FIG. 4 show that after adjusting the pH above 8, DMG
It is shown that the Pd removal rate is further increased when is added so that the molar ratio (Pd in the liquid after adjusting DMG / pH) is 2 or more.

Next, an example in which Pt is recovered from the chloroplatinic acid solution by the method of the present invention is shown as Example 2.

Example 3 By the method of Example 1, a high-purity Pt-containing solution from which Pd has been removed is obtained. At this time, the pH when adding DGM was adjusted to 8.5. High purity Pt obtained
46 L of concentrated hydrochloric acid is added to 460 L of the containing solution to make a 1 M hydrochloric acid solution. Add 200 g / L ammonium chloride solution to add P
Crystallization is performed using t as ammonium chloroplatinate. The purity of the platinum sponge obtained by firing this ammonium chloroplatinate is 9
It was 9.95% or more.

[0018]

As described above, in the present invention, after adjusting the pH of the aqueous solution containing platinum and palladium to more than 8, dimethylglyoxime is added to the Pt aqueous solution to obtain a high removal rate of Pd. I was able to separate it. In addition, the addition amount of DMG was changed to a molar ratio (DMG /
By adjusting the Pd in the liquid after pH adjustment to 2 or more, it was possible to obtain the effect of separating Pd with a higher removal rate. This Pd separation method is particularly effective in separating Pd from the Pd-containing Pt aqueous solution obtained by the smelting step. Further, according to the method of the present invention, high-purity Pt can be obtained by crystallizing Pt from the Pt aqueous solution from which Pd has been separated.

[Brief description of drawings]

FIG. 1 is a flowchart showing a platinum recovery process (Pt process) in a smelting process.

FIG. 2 is a flowchart showing a palladium removal step (Pd removal step) of the present invention.

FIG. 3 is a diagram showing the effect of neutralization pH on Pd removal.

FIG. 4 is a diagram showing the effect of the amount of DMG added on Pd removal.

Claims (4)

(57) [Claims] 1. An aqueous solution containing platinum and palladium is adjusted to a pH of more than 8 and then dimethylglyoxime is added to separate the palladium from the aqueous solution containing platinum and palladium. How to separate. 2. The method according to claim 1, wherein the addition amount of dimethylglyoxime is 2 or more in terms of molar ratio with respect to palladium in the liquid. 3. The method according to claim 1, wherein the aqueous solution containing platinum and palladium is the aqueous solution obtained from the platinum extraction step in the smelting step. 4. A method for recovering high-purity platinum from a platinum-containing aqueous solution after separating palladium by the method according to claim 1.