JPS58135128A - Recovery of indium - Google Patents

Abstract

PURPOSE:To recover In and Sn from an aqueous solution acidified with sulfuric acid or an aqueous solution of hydrofluorosilicic acid containing ions of In and Sn, in high recovery, by the combination of the extraction with an organic solvent containing alkyl phosphate with the back extraction with sulfuric acid containing free sulfuric acid at a specific concentration. CONSTITUTION:An aqueous solution acidified with sulfuric acid or an aqueous solution of hydrofluorosilicic acid containing indium ion and tin ion is brought into contact with an organic solvent solution containing alkyl phosphate to extract the indium ion and the tin ion in the organic solvent solution. The organic solvent solution containing the extracted indium ion and tin ion is brought into contact with an aqueous solution acidified with sulfuric acid containing 550-1,000g/1 of free sulfuric acid to convert the tin ion to the crystal of tin sulfate. The selective removal of tin can be carried out by the above back extraction with the aqueous solution acidified with sulfuric acid. When the concentration of the free sulfuric acid is <550g/1, the ratio of tin removal by the back extraction is lowered and the amount of tin remaining in the organic phase is increased. When the concentration of the free sulfuric acid exceeds 1,000g/1, the amount of indium extracted together with tin by the back extraction becomes undesirably high.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for concentrating and recovering indium from an acidic sulfuric acid aqueous solution or an aqueous silicofluoric acid solution containing indium and tin by solvent extraction.

Indium exists in extremely small amounts in various raw material ores for smelting, such as zinc, lead, copper, and tin, and does not exist as an ore of indium alone. Therefore, it is necessary to recover indium by processing these smelting intermediate products containing trace amounts of indium, which are both contained in steel and zinc.

Since it requires a separate operation tube for tin, cadmium, arsenic, and many other metals, many processes have to be combined, which is not industrially or economically advantageous.

However, in recent years, the technology of solvent extraction has been developed, and many methods have been published for extracting indium from an aqueous solution containing indium and performing S-condensation.

As described above, the present invention is advantageous in that when indium ions and tin ions coexist, for example, in the reflux solution in tin electrolytic refining, tin electrolysis, lead-tin alloy electrolyte, etc., indium accumulates.

This invention relates to an effective method for fractionating indium and tin and concentrating indium when they coexist with tin ions.

Originally, indium and tin have similar electrochemical properties, and although the tin in the electrolytic solution is mainly 21dj, some of it is oxidized and becomes 41+tj.

The coexistence of seven is not simple. Indium ion and -
Solvent extraction of ions is possible with an aI# medium containing dialkyl phosphoric acid, and furthermore, 501-/-g from the above organic solvent containing extracted indium ions and tin ions.
The following play #1fIIItII! The method of back-extracting indium and tin with an aqueous solution containing or hydrochloric acid is USP
Specification No. 3462352 and JP-A-55-14873
It is disclosed in Publication No. 5.

However, in these known methods, even if the 1IllIl[, O/A ratio, or contact time in back extraction of each back extraction solution is varied, both indium and tin ions are back extracted at the same time, and sufficient amounts of indium and tin ions are removed. I was unable to achieve a layered effect. In addition, the above indium and til
500? /1 or more free 1] 11 sulfur #1
When mixed with an aqueous solution containing 1, the relationship with the extract (a third phase is generated, phase separation becomes poor, and as mentioned above,
Since the separation property of indium and tin is also poor, it is practically 500?
/Regret to surpass IJ! It has been held that concentrated aqueous solutions cannot be used for back extraction of this solvent.

Furthermore, as a method for separating indium and tin, a method has been proposed in which tin ions are first separated by displacement using zinc powder, followed by the above-mentioned solvent extraction, and then back-extracted with hydrochloric acid. On the contrary, the zinc powder 11 conversion method dissolves zinc, and the electrolyte itself cannot be reused, so it is necessary to create and adjust a new electrolyte. Furthermore, since the tin sponge recovered contains a large amount of undecomposed zinc, another one is required to recover the tin.

The present inventors solved the above-mentioned drawbacks of the prior art, extracted and recovered indium from a sulfuric acid aqueous solution or a silicic acid aqueous solution containing indium and tin in a high yield, and electrolyzed the aqueous solution from which indium was extracted again. Recovery method for indium that can be used for We have arrived at the present invention, which achieves the objective by increasing the free sulfuric acid sKt of sulfuric acid #[for back extraction combined with extraction with Jl16.

That is, the gist of the present invention is to convert a sulfuric acid acidic aqueous solution or a silifluoric acid aqueous solution containing indium ions and tin ions into alkylphosphorus #! Includes *bath! The indium ions and -ions' are extracted into the organic solvent solution by contacting with $8 liquid, and then the extracted indium ions and tin ions are added to the organic solvent solution containing tr550), /J
-1000)/J of free M sulfuric acid in the range of 1-rf#. According to the present invention, 1 g 1 m of an organic solvent containing di-alkyl phosphorus from which indium and tin have been conventionally extracted
It has been said that sulfuric acid aqueous solutions containing free sulfuric acid of 11C500f74 or more cannot be used when back-extracting with
5501f/-e ~ 100OP/J for back extraction of organic solvents containing alkyl phosphorus 111 from which indium and tin have been extracted
By using a sulfuric acid aqueous solution containing free 1111 sulfuric acid in the range of After solid-liquid separation using the well-known technology of
Next, when liquid phase separation is performed, the third phase disappears and phase separation is easily performed, resulting in a solvent phase with an increased abundance ratio of In/8.

This solvent phase with an increased abundance ratio of In/8n can be easily extracted as a concentrated aqueous solution of indium by back-extraction using known hydrochloric acid.

In the present invention #i, the alkyl phosphoric acid used for extraction of indium and tin ions includes di- or mono-alkyl esters of phosphoric acid, phosphorous acid, or hypophosphorous acid, and the alkyl group is octyl 41! ! It is preferable that the liquid phase has a small loss of water to the liquid phase. Specific examples include di-2-ethylhexyl phosphoric acid, 2-ethylhexyl phosphoric acid, 2-ethylexylphonic acid, and mixtures thereof.

The organic solvent for dissolving these alkyl phosphoric acids may be any stable compound that does not mix with water and freely dissolves the alkyl phosphoric acid into II, such as paraffinic kerosene, Shersol 70. Naphthenic notispazole, aromatic 7erzorum, etc. have a gT capacity, but kerosene is preferred because it is cheap.Next, the free sulfur rsav of the sulfuric acid acidic aqueous solution used for back extraction is 550 f/l-1000 t/J.
(D range, preferably in the range of 60 (1/J to 850 P/J). If the free end sulfuric acid concentration is less than 550 f/l,
The rate of tin removal by back extraction decreases and the amount of tin remaining in the organic phase increases.

Also, if the free 4-sulfuric acid degree exceeds 1ooo)/J.

The upper limit is 100 OP/J because the amount of indium that is back-extracted with tin increases, which is undesirable, and in some cases, the compound used in the organic phase deteriorates.

The young fruits of the present invention are as follows.

Since the detinning rate of the 111gl acid acid oil extraction process is high, the indium concentrated water obtained from the hydrochloric acid back extraction process111? [The inside is low, this #! It is easy to remove tin from the liquid (cementation with indium), and it is possible to recover indium in a high yield.

(2) Conventionally, when indium accumulated in electrolyte solutions such as tin electrolysis, lead electrolysis, and clam tin alloy electrolysis is recovered by solvent extraction, a detining process (replacement separation with zinc powder) is carried out prior to the solvent extraction. ), and as a result, it could not be reused as an electrolyte. However, according to the *invention, a 4FFL detinning process (reverse sulfuric acid extraction process) is provided for the organic phase separated after solvent extraction, and the aqueous phase after solvent extraction is Although the contents of tin and indium decreased, there was no change in the amount of sulfate, so tin sulfate crystals were dissolved in the water tank after the extraction of the molten metal to reduce the tin ion content of the raw electrolyte. It can be returned to normal temperature and reused as an electrolyte.

(3) The *111 liquid separated from the liquid phase can be repeatedly used as a back extraction solution for detining by simply replenishing the amount of sulfuric acid consumed as tin sulfate. Moreover, indium ions are contained in this sulfuric acid solution. Since the amount is not exceeded by a certain amount, there is no effect on the recovery of indium.

(4) The more highly concentrated sulfuric acid is used, the larger the 0/A ratio can be selected, which is very advantageous in actual operation.

The separated and recovered tin sulfate is precipitated as crystals and has very high purity as tin sulfate. Therefore, it can be said that the present invention also provides a method for recovering tin sulfate crystals.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

゛Example 1 Indium ion = rtip, m ion approximately 35? DZEHP
DP-8R manufactured by Daihe Kagaku Co., Ltd. was used as a sample with kerosene.
”1lIa18J diluted to fit/4 (o/a=4
: 5) Extraction operation was carried out at room temperature using t-t, followed by free sulfuric acid 650) / J of back-extracted sulfuric acid solution for detining 800
A sickle obtained by obtaining crystals of tin sulfate with aj (0/mu=10:1),
Table 1 shows the results obtained when carrying out a series of steps of phase separation and back extraction of indium with 7N hydrochloric acid (110/mu = 8:l).

From Table 1, 11** of organic 5m
The content of In and 80 present in 5a and the back extraction wheel after treatment are as follows: ll2m.

Its excellent selective detinning effect is obvious.

Table 2 Comparative Example Similar to J1Gal, acid-related silica iron containing indium and -electrode mteixoJKnL, D2EMPhf>
When 1w5et74 kerosene #1E8J was used for tsukude extraction and direct hydrochloric acid back extraction was performed on the organic fII-mediated liquid without merocytic de-extraction using OC, the results shown in Summary 39 were obtained. It was done. @Acid reverse sleeve release is shown in 1i13*.

(a) Two-stage back extraction with 6N4 acid and 9NkIi @ Three conditions were used: one-stage back extraction with 1-8N acid and one-stage back extraction with 19N hydrochloric acid.

Comparing the contents of In and An in the hydrochloric acid back extraction solution and the ratio to the original liquid in Table 3 with the data in Table 1 according to the method of the present invention, the effect of providing one sulfuric acid detinning becomes even clearer.

Patent applicant Mitsubishi Metals Corporation Agent Yoshinao Shirakawa

Claims (1)

[Claims] 11) Convert sulfuric acid acidic water S solution containing indium ions and tin ions or silicofluoric acid water F# solution to alkyl phosphoric acid t-
The indium ions and tin ions are extracted into the liquid by contacting with an organic solvent solution, and then the extracted indium ions and tin ions are added to the organic solvent f#Il[550? /J ~ 100 (includes a selective detinning step of contacting an acidic sulfuric acid aqueous solution containing g12 of free S sulfur with an a range of 1/A and back-extracting the - ions as crystals of tin sulfate into the mg of sulfuric acid acidic water. A method for recovering indium, characterized by the following.