JP2890830B2 - Purification method of scandium oxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to one or two types of impurity metals (Fe, Al, Sn, Zr, Ti, Pb, Ca, Cu, Zn, Th) contained in scandium oxide. (See more than one species). Scandium (Sc) has almost no raw material ore that can be used industrially, and is industrially separated and recovered from uranium leachate, titanium (Ti) slag, tin (Sn) slag, and the like. However, the above-mentioned metals are contained in the above-mentioned raw materials, and it is necessary to separate these metals in order to recover scandium. The present invention provides a method for purifying scandium oxide having a good separation effect and high recovery efficiency.

[Problems of the Prior Art] As a method for separating the impurity metal from an aqueous solution containing the above-mentioned impurity metal ion together with scandium ion, the following method has been conventionally known.

(A) Add an alkali such as ammonia or caustic soda to the above solution and hydrolyze it at around pH 3-4 to make Al, Sn, Zr,
A method of precipitating a hydroxide such as Ti.

(B) A method in which hydrochloric acid and nitric acid are added to the above solution, and Zr, Ti, Hf, and Th are separated at the time of adsorption by ion exchange.

(C) The above solution is made into an acidic solution of hydrochloric acid and nitric acid, and
Separation at the time of adsorption and elution of ion exchange using a different ion exchange resin.

(D) A method in which the above solution is converted into an acidic solution of hydrochloric acid and nitric acid, and Zr, Ti, Hf, and Th are separated by solvent extraction.

(E) The above solution is made into an acid solution of hydrochloric acid and nitric acid, and
Separation by solvent extraction using a different solvent.

However, each of the above methods has the following problems. For example, each of the above methods (a) to (e) cannot separate the impurity metal alone at the same time, and the methods (a) and (b)
As described in (a) or (c), (d) and (e), the above methods are combined for separation and purification, and no effective method for simultaneously separating the impurity metal from scandium has been known.

[Knowledge of Problem Solving] The present inventors have attempted to separate scandium from the impurity metal by a precipitation separation method. When a complexing agent is used, scandium forms a complex in an alkaline region of about pH 9.5. Focusing on the fact that the impurity metal does not form a complex, a complex of scandium is formed in an alkaline solution, which is dissolved in the alkaline solution, and the precipitate of the impurity metal is separated effectively and easily. It has been found that it can be separated from impurity metals.

[Constitution of the Invention] The present invention provides a method for purifying scandium oxide containing the above-mentioned impurity metal, having the following constitution.

(1) Impurity metals (Fe, Al, Sn, Zr, Ti, Pb, Ca, Cu,
Scandium oxide containing one or more of Zn and Th) is dissolved at a pH of 2 or less using hydrochloric acid or nitric acid, and an alkali other than carbonate is added to the solution to adjust the pH to 3 or less.
The scandium and the impurity metal were precipitated as hydroxides by adjusting as described above, and a carbonate compound was added to the solution containing the precipitate to form a scandium complex under alkalinity and redissolved, thereby precipitating the remaining impurity metal. A method for purifying scandium oxide, comprising recovering scandium oxide after separation by filtration.

(2) After separating the precipitate of the impurity metal by filtration, hydrochloric acid or nitric acid is added to the filtrate, and then oxalic acid or an oxalate compound is added to precipitate scandium oxalate. The precipitate is collected by filtration and roasted. The purification method according to claim 1, wherein the scandium oxide is recovered by heating.

(3) The method according to claim 1 or 2, wherein the complex is formed by the carbonate compound at a temperature of 60 ° C or lower.

[Detailed Description of the Invention] The method of the present invention relates to a method for purifying scandium oxide containing an impurity metal. In the present purification method, the impurity metals are Fe, Al, Sn, Zr, Ti, Pb, Ca, C
It refers to one or more of u, Zn, and Th. Hereinafter, a method for purifying scandium oxide containing the impurity metal will be specifically described.

The scandium oxide containing the impurity metal is dissolved at a pH of 2 or less using hydrochloric acid or nitric acid while heating. If the pH of the solution exceeds 2, undissolved scandium oxide remains, which is not preferable. An alkaline substance such as aqueous ammonia or caustic soda is added to the solution, and the pH is adjusted to 3 or more to form hydroxide precipitates of scandium and impurity metals. When the pH of the solution is less than 3, precipitation of scandium hydroxide is not sufficient. When the pH of the solution exceeds 7, the consumption of alkali increases.

A carbonate compound as a complexing agent for the scandium precipitate is added to the solution containing the hydroxide precipitate of the scandium and the impurity metal. By adding this carbonate compound, the scandium precipitate forms a complex under alkalinity and dissolves again in the liquid. On the other hand, the impurity metal remains as a hydroxide precipitate or a carbonate precipitate. Therefore, by filtering this and separating the precipitate, scandium and the impurity metal can be separated.

As a complexing agent, sodium carbonate, potassium carbonate, ammonium carbonate and the like can be used. As shown in Examples described later, the solution becomes alkaline by adding these carbonate compounds, and the scandium precipitate is complexed and dissolved. This complexing agent is added as a powder or a solution. In order to prevent the liquid volume from increasing, it is preferable to add the powder. In addition, when adding the carbonate compound as a complexing agent, the liquid temperature is preferably as low as possible, suitably at 60 ° C. or lower, and more preferably at room temperature. If the liquid temperature is higher than this, scandium complex formation ability is weakened, and part of scandium remains as a precipitate, which is not preferable.

The scandium from which the impurity metal has been separated as described above is recovered as an oxalate precipitate. Specifically, hydrochloric acid or nitric acid is added to the solid-liquid separated scandium solution to adjust the pH to about 2 to 0.8 as shown in Examples 1 to 3, and oxalic acid or an oxalate compound is added thereto to convert the scandium to oxalate. Turn to precipitate. The precipitate is collected by filtration. As the oxalic acid compound to be added, ammonium oxalate is preferable since impurities are not mixed.

Examples and Comparative Examples Hereinafter, the present invention will be specifically described with reference to Examples.

Example 1 To 145 ml of a scandium hydrochloride acid solution of pH 0.8 containing impurities shown in Table 1, 16 ml of commercially available special grade ammonia water was added, and p
H was set to 6.5. This produced a hydroxide precipitate of scandium and the above impurities. To the solution containing the precipitate, 25 g of ammonium carbonate was added as a powder, and the mixture was stirred for 10 minutes. The pH of the solution at this time was 10.4. This was filtered to separate impurities, and 298 ml of a filtrate was obtained. To this was added 30 ml of commercially available special grade hydrochloric acid to adjust the pH of the solution to 1.0. afterwards,
13g of reagent grade oxalic acid was added as powder and stirred for 5 minutes,
A scandium oxalate precipitate formed. Scandium oxalate obtained by filtering this precipitate was roasted at 700 ° C. to obtain 2.8 g of purified scandium oxide. This was subjected to analysis. The results of this analysis are shown in Table 1. The results show that all impurity metals have been removed and purified. The recovery rate of scandium was 85%.

Example 2 To 100 ml of a scandium nitrate acid solution (Sc concentration: 21.45 mg / l) containing impurities shown in Table 2 and having a pH of 1.5, 11 ml of commercially available special grade ammonia water was added to adjust the pH to 8.8. This produced a hydroxide precipitate of scandium and the above impurities. 100 ml of a solution of 200 g / l sodium carbonate in the solution containing this precipitate
Was added and stirred for 10 minutes. At this time, the pH of the solution was 10.2. This was filtered to separate impurities to obtain 318 ml of a washing solution. To this was added 35 ml of commercially available special grade nitric acid to adjust the pH of the solution to 0.8.
Was adjusted. Thereafter, 16 g of a reagent grade ammonium oxalate was added as it was and stirred for 5 minutes to produce a scandium oxalate precipitate. This was filtered and the scandium oxalate obtained was roasted at 700 ° C. to obtain 2.83 g of purified scandium oxide.
This was subjected to analysis. The results of this analysis are shown in Table 2. The results show that all impurity metals have been removed and purified. The recovery rate of scandium was 86
%Met.

Example 3 To 100 ml of a scandium nitrate acid solution of pH 1.5 containing impurities shown in Table 2, 11 ml of commercially available special grade ammonia water was added to adjust the pH to 8.8. This produced a hydroxide precipitate of scandium and the above impurities. To the solution containing the precipitate, 80 ml of a solution of 200 g / l of sodium bicarbonate was added and stirred for 10 minutes. The pH of the solution at this time was 8.1. This was filtered and impurities were separated to obtain 257 ml of a filtrate. To this was added 32 ml of commercially available special grade nitric acid to adjust the pH of the solution to 0.8. Thereafter, 16 g of a reagent grade ammonium oxalate was added as it was and stirred for 5 minutes to produce a scandium oxalate precipitate.
Thereafter, in the same manner as in Example 2, purified scandium oxide 3.03
g was obtained. The results of the analysis are shown in Table 3. The results show that all impurity metals have been removed and purified. The recovery rate of scandium was 92%.

Comparative Example To 100 ml of a scandium nitric acid acidic solution having a pH of 1.5 and containing impurities shown in Table 2, 13 g of reagent grade oxalic acid was added as it was, and stirred for 5 minutes to form a scandium oxalate precipitate. Thereafter, in the same manner as in Example 2, the purified scandium oxide was used.
3.1 g was obtained. The results of this analysis are shown in Table 4. From the results shown, a refining effect can be obtained for some impurity metals, but the refining effect is much lower than in Examples 1 to 3, and the refining effect is significantly lower.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Etsuji Kimura 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsui Kinzoku Co., Ltd. Central Research Laboratory (58) Field surveyed (Int.Cl. ⁶ , DB name) C01F 17 / 00

Claims (3)

(57) [Claims] 1. An impurity metal (Fe, Al, Sn, Zr, Ti, Pb, C
a, Cu, Zn, or Th) is dissolved in hydrochloric acid or nitric acid at a pH of 2 or less using hydrochloric acid or nitric acid, and an alkali other than carbonate is added to the solution to adjust the pH. By adjusting the amount to 3 or more, scandium and the impurity metal are precipitated as hydroxides, and a carbonate compound is added to the solution containing the precipitate to form a scandium complex under alkalinity and redissolved to precipitate the remaining impurity metal. A method for purifying scandium oxide, comprising collecting scandium oxide after separating by filtration. 2. The precipitate of the impurity metal is separated by filtration, and then hydrochloric acid or nitric acid is added to the filtrate, followed by adding oxalic acid or an oxalate compound to precipitate scandium oxalate.
The purification method according to claim 1, wherein the precipitate is collected by filtration and roasted to recover the scandium oxide. 3. The method according to claim 1, wherein the complex is formed by the carbonate compound at a temperature of 60 ° C. or lower.