JPS6115936B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for selectively extracting indium from a solution containing indium and various metals, and particularly relates to a method for selectively extracting indium from a solution containing indium and various metals. The present invention relates to a method for selectively extracting . Smoke ash produced in the zinc and lead smelting process,
Trace amounts of indium are contained in various residues such as anode slime, electrolytic waste, etc., and attempts have been made in recent years to recover indium from these. Methods for separating indium include a method of precipitating it in the form of sulfide or hydroxide, and a method of utilizing displacement precipitation reaction (cementation). The former method requires complicated and troublesome processing operations due to the presence of precipitates, and the separation of indium from other metals is not good.On the other hand, the latter method also uses zinc, which is used for replacement,
If nobler metals such as cadmium and aluminum are present together with indium, separation from these metals cannot be achieved. Apart from these methods,
There is a method known as solvent extraction. The solvent extraction method separates indium from an indium-containing aqueous solution using an organic solvent containing an extractant that can selectively extract indium. When selecting an extractant, it must be taken into consideration that the extractant does not mix with the indium-containing aqueous solution and has the ability to selectively and efficiently extract only indium ions from the aqueous solution. Furthermore, the extractant is generally diluted with a diluent to reduce its viscosity, improve the dispersion of the extractant, and increase the contact efficiency of the extractant, so it dissolves well in the diluent. It is also necessary.
In addition, since back-extraction is performed after the extraction operation, it is also necessary to easily perform the back-extraction operation. Several extractants have been developed so far, but all of them have problems such as poor selectivity in extracting only indium ions from a large number of metal ion species, difficulty in back-extraction, and harsh extraction conditions. I wasn't completely satisfied. Therefore, attempts are still being made in the art to obtain optimal extractants for the selective extraction of indium. In response to such demands, the present invention was developed as a result of extensive research on indium solvent extractants.
-Ethylhexylphosphonic acid mono-2-ethylhexyl ester was found to be extremely effective in selectively extracting indium. The above-mentioned extractant is extremely selective to indium, and by appropriately selecting the conditions, it is possible to extract 98% or more of indium, and the back extraction operation can be performed easily. Thus, the present invention provides an indium solution comprising contacting a sulfuric acid acidic solution containing indium and other metals with an organic solvent containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant at a pH of 1.0 or less. A selective separation method is provided. Furthermore, the present invention provides a method for contacting a sulfuric acid acidic solution containing indium and other metals with an organic solvent containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant at a pH of 1.0 or less, and after extraction containing indium. A method for selective separation of indium is provided which comprises extracting the solvent with hydrochloric acid or sulfuric acid. The present invention will be explained in detail below. The above-mentioned leachate, which is a by-product of various smelting processes of zinc and lead, contains not more than 1.0 g/indium, but also various metal ions such as thallium, cadmium, zinc, arsenic, iron, and manganese. To selectively extract indium from solutions containing many metal ions, 2-ethylhexylphosphonic acid mono-2-
Organic solvents containing ethylhexyl ester as an extractant are extremely effective. 2-Ethylhexylphosphonic acid mono-2-ethylhexyl ester has the following structural formula: For the reasons mentioned above, the above-mentioned extractant is usually used after being diluted with a diluent such as mineral oil, a mixture of mineral oil and alcohol, or toluene. The dilution level is about 3 to 50% by volume. In order to selectively separate indium from an acidic sulfuric acid solution containing indium and other metals, which is the object of the present invention, it is important that the pH is 1.0 or less. The indium content can be processed from a low value of 1g/or less to a high value of around 30g/. The contact between the indium-containing sulfuric acid acidic solution and the organic solvent containing the extractant can be carried out either batchwise or continuously using well-known mixer-settler equipment, extraction towers, centrifugal extractors, and the like. The mixing temperature is chosen between 0 and 70°C, preferably between 10 and 40°C, depending on the diluent used. The volume ratio (O/A ratio) of the organic phase (organic solvent) to the aqueous phase (liquid to be treated) during contact is 1/15~
The ratio is about 5/1, preferably 1/2 to 2/1, and can be appropriately selected depending on the equipment used and operating conditions. The contact time depends on the contact efficiency, but from 5 to
60 minutes, usually 10 to 30 minutes is sufficient. The organic solvent after extraction is back-extracted with sulfuric acid or hydrochloric acid. Hydrochloric acid has better back extraction ability, but either can be selected depending on the process conditions. In the case of sulfuric acid, a concentration of 1 to 10 normal is selected, and in the case of hydrochloric acid, a concentration of 1.1 to 7 normal is selected.
O/A ratio is 1/5 to 10/1, preferably 2/1 to
The ratio is 5/1, and the temperature is 30-70℃, which is slightly higher than the extraction temperature. The contact time depends on the type of equipment used, but 5 to 30 minutes is sufficient. When the extractant accumulates iron and the like during cyclical use and its extraction ability decreases, the extraction ability can be recovered by washing it with mineral acid or the like. Example 1 After adjusting 90 ml of an aqueous solution containing various metal ions in addition to indium shown in the table to the five sulfuric acid concentrations shown in the same table, it was mixed with dispersol (Ciel An extraction test was carried out using an organic solvent diluted to 10% by volume with a chemical trade name. The results are shown in the table. The extraction conditions were as follows:
Temperature 20℃, time 15 minutes, stirring blade rotation speed 750rpm,
O/A=90ml/90ml.

[Table] From the table, it can be seen that the organic solvent containing the above extractant has an extremely excellent selective extraction property for indium.
It can be seen that almost no metal ions other than indium are extracted. As the sulfuric acid concentration increases, the indium extraction rate tends to decrease. The graph in the drawing shows the relationship between the indium extraction rate and the sulfuric acid concentration. Example 2 Using the same organic solvent as in Example 1, the organic solvent containing 0.632 g/indium after indium extraction was back-extracted using sulfuric acid and hydrochloric acid solutions. Sulfuric acid solutions for back extraction were used in concentrations of 100 g/, 300 g/, and 500 g/, and hydrochloric acid solutions were used in concentrations of 35 g/, 105 g/, and 175 g/. The back extraction conditions were as follows: O/A = 60ml/60ml, stirring rotation speed.
750rpm, temperature 50℃, time 15 minutes. The indium concentration of the liquid (aqueous phase) after back extraction is shown in the table. As can be seen from the table, hydrochloric acid has better back extraction performance. In the case of sulfuric acid, the results of back extraction are not good if the concentration is less than 300 g/concentration, but by repeating the back extraction operation two or more times, it can be raised to the same level as when the concentration is 300 g/concentration or more.

【table】

[Table] Example 3 3 diluted with dispersol to 3% by volume, 5% by volume and 10% by volume using 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant.
An extraction test was conducted on a sulfuric acid solution (25 g/) with a pH of 0.75 containing 1.01 g/indium using a different organic solvent. Other extraction conditions were the same as in Example 1. The indium concentration of the post-extraction solution is 0.139g/, 0.016g/ depending on the extractant concentration of 3%, 5%, and 10%, respectively.
and 0.003g/. Considerably high extraction rates can be obtained using organic solvents with extractant concentrations as low as 3%. Example 4 2- after extraction operation containing 1.01g/indium
Using ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant, an organic solvent diluted to 10% by volume with dispersol was added to a sulfuric acid solution.
Back extraction was carried out at temperatures of 30°C, 50°C and 70°C. Sulfuric acid concentration is 50g/, 100g/, 200g/ and
Four types of 300g/each were used. The reverse extraction conditions are
O/A=1, rotation speed 750 rpm, and time 15 minutes. The indium concentration of the liquid after back extraction (aqueous phase) was as follows.

[Table] From the table, it can be seen that the higher the back extraction temperature, the better the back extraction rate. It is noteworthy that the combination of a back extraction temperature of 70° C. and a sulfuric acid concentration of 300 g/ml can achieve an indium recovery of over 97%. The present invention provides a method for extracting and separating indium using an organic solvent that is extremely selective for indium, and by selecting appropriate conditions, substantially indium can be removed from an aqueous solution containing a large number of metal ions. It is extremely effective for recovering indium from various by-products of the smelting process, such as lead slag, because it can recover indium at a level of 97% or more, and the back extraction operation is easy.

[Brief explanation of the drawing]

The drawing shows the relationship between the indium extraction rate of the organic solvent used in the present invention and the concentration of sulfuric acid in the preliquid.

Claims (1)

[Claims] 1 A solution of sulfuric acid containing indium and other metals is mixed with 2-ethylhexylphosphonic acid mono2
- A selective separation method for indium that consists of contacting with an organic solvent containing ethylhexyl ester as an extractant at a pH of 1.0 or less.