JP5994912B2 - Scandium recovery method - Google Patents

Description

  The present invention relates to a method for recovering scandium, more specifically, a method for efficiently recovering scandium contained in nickel oxide ore using a chelate resin.

  Scandium is extremely useful as an additive for high-strength alloys and as an electrode material for fuel cells. However, since the production amount is small and expensive, it has not been widely used.

  By the way, nickel oxide ores such as laterite or limonite ore contain a small amount of scandium. However, since nickel oxide ore has a low nickel-containing grade, it has not been industrially used as a nickel raw material for a long time. Therefore, there has been little research on industrially recovering scandium from nickel oxide ore.

  However, in recent years, an HPAL process in which nickel oxide ore is charged into a pressure vessel together with sulfuric acid and heated to a high temperature of about 240 to 260 ° C. to separate the solid and liquid into a leachate containing nickel and a leach residue is being put into practical use. is there. Impurities are separated by adding a neutralizing agent to the leachate obtained by this HPAL process, and then a sulfiding agent is added to recover nickel as nickel sulfide. The nickel sulfide is then recovered in the existing nickel smelting process. Electrical nickel and nickel salt compounds are obtained by treatment.

  When the above HPAL process is used, scandium contained in the nickel oxide ore is contained in the leachate together with nickel (see Patent Document 1). When the neutralization agent is added to the leachate obtained by the HPAL process to separate impurities, and then the sulfiding agent is added, nickel is recovered as nickel sulfide, while scandium is acidic after the addition of the sulfiding agent. Since it is contained in the solution, nickel and scandium can be effectively separated by using the HPAL process.

  As a method for recovering scandium from the acidic solution, it has been proposed to adsorb scandium to a chelate resin having an iminodiacetate as a functional group to separate and concentrate the scandium (see Patent Documents 2 to 4). .

JP-A-3-173725 JP-A-1-133920 JP-A-9-176756 JP-A-9-194211

  However, even if the methods described in Patent Documents 1 to 4 are used, there is a further problem in order to efficiently recover high-quality scandium.

  Nickel oxide ores contain not only scandium but also aluminum and chromium. Among these, chromium has a property of strongly adsorbing to the chelate resin, and therefore once chromium is adsorbed to the chelate resin, it is difficult to separate the chromium from the chelate resin.

  When impurities are adsorbed on the chelate resin, the amount of scandium adsorbed on the chelate resin thereafter decreases, so that the equipment efficiency decreases. Further, since both scandium and impurities are adsorbed on the chelate resin, the quality of the recovered scandium is reduced when the chelate resin is reused after the impurities are adsorbed.

  An object of the present invention is to efficiently recover high-quality scandium when recovering scandium from nickel oxide ore using a chelate resin.

  As a result of intensive studies to solve the above problems, the present inventors can remove impurities adsorbed on the chelate resin by bringing sulfuric acid of a specific normality into contact with the chelate resin after elution of scandium. As a result, the present invention has been completed. Specifically, the present invention provides the following.

  (1) In the present invention, after iminodiacetic acid is used as a functional group, sulfuric acid of 0.1 N or less is brought into contact with a chelate resin adsorbed with scandium, aluminum and chromium, and after removing aluminum from the chelate resin, This is a method for recovering scandium, in which sulfuric acid of 1N or more and less than 3N is brought into contact to obtain a scandium eluent.

  According to the present invention, since the chelate resin after eluting scandium is brought into contact with sulfuric acid having a specific normality, high-quality scandium can be efficiently recovered.

It is a figure for demonstrating the collection method of the scandium which concerns on this invention. It is a figure which shows the relationship between pH of the metal containing solution which let the chelate resin flow, and the adsorption amount to the chelate resin of the metal. It is a figure which shows the relationship between the repetition frequency of a scandium elution process, and the density | concentration of the scandium contained in the scandium eluent after a repetition.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. Can do.

  FIG. 1 is a diagram for explaining a scandium recovery method according to the present invention. The present invention is a leaching step S1 in which nickel oxide ore containing scandium, aluminum and chromium is charged together with sulfuric acid into a pressure vessel and separated into a leaching solution and a leaching residue under high temperature and high pressure, and the leaching solution is neutralized. Neutralizing step S2 to obtain a neutralized starch and a liquid after neutralization by adding an agent, a sulfurizing step S3 in which a sulfurizing agent is added to the liquid after neutralization and separated into nickel sulfide and liquid after sulfurization, The post-solution is brought into contact with a chelate resin having iminodiacetic acid as a functional group to adsorb scandium to the chelate resin, and sulfuric acid of 0.1 N or less is brought into contact with the chelate resin adsorbing scandium in the adsorption step S4. The aluminum removal step S5 for removing the aluminum adsorbed on the chelate resin in the adsorption step S4, and sulfuric acid of 1N or more and less than 3N on the chelate resin that has undergone the aluminum removal step S5. A scandium elution step S6 to obtain a scandium eluent, and a chelate resin that has undergone the scandium elution step S6 is contacted with 3N or more sulfuric acid to remove chromium adsorbed on the chelate resin in the adsorption step S4; including.

  In the present invention, in order to efficiently separate scandium and impurities adsorbed on the chelate resin in the adsorption step S4, first, aluminum is separated with sulfuric acid having a relatively low normality, and then scandium is separated with sulfuric acid having a higher normality. Separate, and then separate the chromium with higher normality sulfuric acid. As described above, the present invention is characterized in that the separation of the metal ions adsorbed on the chelate resin is divided into three stages, whereby high-quality scandium can be efficiently recovered as compared with conventionally known methods.

<Leaching step S1>
In the leaching step S1, nickel oxide ore containing scandium, aluminum, and chromium is charged into a pressure vessel together with sulfuric acid, and is solid-liquid separated into a leachate and a leach residue under high temperature and pressure.

  The leaching step S1 may be performed according to a conventionally known HPAL process, and is described in Patent Document 1, for example.

<Neutralization step S2>
In the neutralization step S2, a neutralizing agent is added to the leachate obtained in the leaching step S1 to obtain a neutralized starch and a neutralized solution. Valuable metals such as scandium and nickel are contained in the solution after neutralization, and most of impurities such as aluminum are contained in the neutralized starch.

  The neutralizing agent may be a conventionally known neutralizing agent, and examples thereof include calcium carbonate, slaked lime, and sodium hydroxide.

  In the neutralization step, it is preferable to adjust the pH to a range of 1 to 4. A pH of less than 1 is not preferable because neutralization is insufficient and the neutralized starch and the post-neutralized solution may not be separated. If the pH exceeds 4, not only impurities such as aluminum but also valuable metals such as scandium and nickel are included in the neutralized starch, which is not preferable.

<Sulfurization step S3>
In the sulfiding step S3, a sulfiding agent is added to the neutralized solution to separate the sulfide and the sulfidized solution. Nickel, cobalt, zinc and the like are contained in the sulfide, and scandium and the like are contained in the post-sulfurized solution.

  A conventionally known sulfurizing agent is sufficient, and examples thereof include hydrogen sulfide gas, sodium sulfide, and sodium hydrogen sulfide.

<Adsorption process S4>
In the adsorption step S4, the solution after sulfurization is brought into contact with a chelate resin having iminodiacetic acid as a functional group to adsorb scandium to the chelate resin.

  By the way, the lower the pH range, the smaller the amount of adsorption of impurities contained in the nickel oxide ore. Therefore, the adsorption | suction to the chelate resin of an impurity can be suppressed by letting the liquid of the pH range as low as possible flow through a chelate resin. However, when the pH is less than 2, not only the amount of impurities adsorbed but also the amount of scandium adsorbed decreases. For this reason, it is not preferable to allow a solution in an extremely low pH range to pass through the resin to be adsorbed.

<Aluminum removal step S5>
In the aluminum removal step S5, 0.1 N or less sulfuric acid is brought into contact with the chelate resin having adsorbed scandium in the adsorption step S4, and the aluminum adsorbed on the chelate resin in the adsorption step S4 is removed.

  When removing aluminum, the pH is preferably maintained in the range of 1 to 2.5, and more preferably in the range of 1.5 to 2.0. If the pH is less than 1, not only aluminum but also scandium is removed from the chelate resin, which is not preferable. A pH exceeding 2.5 is not preferable because aluminum is not properly removed from the chelate resin.

<Scandium elution step S6>
In the scandium elution step S6, 1N or more and less than 3N sulfuric acid is brought into contact with the chelate resin that has undergone the aluminum removal step S5 to obtain a scandium eluent.

  When obtaining a scandium eluent, it is preferable to maintain the normality of sulfuric acid used in the eluent within a range of 0.3N or more and less than 3N, and more preferably within a range of 0.5N or more and less than 2N. When the normality is 3N or more, not only scandium but also chromium is contained in the scandium eluent, which is not preferable. When the normality is less than 0.3 N, scandium is not appropriately removed from the chelate resin, which is not preferable.

<Chromium removal step S7>
In the chromium removal step S7, 3N or more sulfuric acid is brought into contact with the chelate resin that has undergone the scandium elution step S6, and the chromium adsorbed on the chelate resin in the adsorption step S4 is removed.

  When removing chromium, if the normality of sulfuric acid used in the eluent is less than 3N, it is not preferable because chromium is not properly removed from the chelate resin.

<Iron removal process>
Moreover, although not shown in figure, iron may be contained as an impurity in nickel oxide ore. In this case, prior to the aluminum removal step S5, sulfuric acid having a normality smaller than the normality of sulfuric acid used in the aluminum removal step S5 is brought into contact with the chelate resin that has adsorbed scandium in the adsorption step S4, and the chelate resin is obtained in the adsorption step S4. It is preferable to remove the iron adsorbed on the surface.

  When removing iron, it is preferable to maintain pH in the range of 1-3. If the pH is less than 1, not only iron but also scandium is removed from the chelate resin, which is not preferable. If the pH exceeds 3, iron is not appropriately removed from the chelate resin, which is not preferable.

<Re-adsorption of scandium eluent on chelate resin>
Although not an essential aspect, a neutralizing agent is added to the scandium eluate obtained in the scandium elution step S6 to adjust the pH to a range of 2 to 4, preferably 2.7 to 3.3 centered on pH 3. (Step S11), then a reducing agent is added (step S12), and then sulfuric acid is added to adjust the pH to a range of 1 to 2.5, preferably 1.7 to 2 centering on pH 2. .3 (step S13), a solution after pH adjustment of the scandium eluate is obtained, and the adsorption step S4, the aluminum removal step S5, and the scandium elution step S6 are performed again using this pH adjusted solution. Preferably it is done. By passing through these steps, the quality of the recovered scandium can be further enhanced. In addition, it is possible to reduce the chemical cost and the equipment scale when separating scandium from the scandium eluent.

  The addition of the reducing agent is preferably carried out so that the oxidation-reduction potential (ORP) is maintained in a range in which the silver / silver chloride electrode is used as a reference electrode and exceeds 200 mV to 300 mV or less. When a sulfiding agent is used as the reducing agent, if the oxidation-reduction potential is 200 mV or less, the sulfur content derived from the added sulfiding agent precipitates as a fine solid, which clogs the filter cloth in the filtration step after sulfiding. This may cause deterioration of solid-liquid separation and decrease in productivity, or clogging in the resin tower or uneven flow of liquid when re-flowing through the chelate resin, resulting in inability to perform uniform flow. obtain. On the other hand, when the oxidation-reduction potential exceeds 300 mV in all reducing agents, problems such as residual iron ions adsorbing to the resin and inhibiting the adsorption of scandium may occur.

  The neutralizing agent may be a conventionally known neutralizing agent, and examples thereof include calcium carbonate. The reducing agent may be a conventionally known reducing agent, and examples thereof include a sulfurizing agent such as hydrogen sulfide gas and sodium sulfide, sulfur dioxide gas, hydrazine, and metallic iron.

  When re-adsorbing the scandium eluent to the chelate resin, the chelate resin that has been used may be reused or a new chelate resin may be used, but from the viewpoint of preventing contamination of impurities. Therefore, it is preferable to reuse the chelate resin that has undergone the chromium removal step S7 or use a new chelate resin. In particular, by reusing the chelate resin that has undergone the chromium removal step S7, not only contamination of impurities can be prevented, but also the amount of chelate resin used can be suppressed.

<Purification of scandium eluent>
By performing the scandium elution step S6 again on the scandium eluate obtained in the scandium elution step S6, the concentration of the scandium eluent can be increased.

  As the scandium elution step S6 is repeated many times, the concentration of the recovered scandium increases. However, if the number of scandium elution steps S6 is repeated too many times, the increase in the concentration of the recovered scandium is reduced. The number of repetitions is preferably 8 times or less.

<Recovery of scandium>
Scandium is oxidized by adding alkali or oxalic acid to the scandium eluent to separate the precipitate and the post-precipitation solution (step S21), and then washing the precipitate with water, drying, and baking. It can be recovered as scandium (step S22).

[Addition of alkali or oxalic acid (step S21)]
In the case of adding alkali to the scandium eluent, it is sufficient that the alkali is a conventionally known alkali, for example, calcium carbonate, slaked lime, sodium hydroxide, etc., but when the scandium eluent is a sulfuric acid solution, the alkali is a calcium salt. In this case, since the gypsum is generated by neutralization, the alkali is preferably sodium hydroxide.

  When adding an alkali to a scandium eluent, it is preferable to adjust pH to the range of 8-9 in process S21. A pH of less than 8 is not preferable because neutralization is insufficient and scandium cannot be sufficiently recovered. If the pH exceeds 9, the amount of neutralizing agent used is increased, leading to an increase in cost.

  By adding oxalic acid to the scandium eluent, higher-grade scandium can be recovered than when adding alkali. The amount of oxalic acid added is not particularly limited, but is preferably 1.05 to 1.2 times the calculated amount of scandium contained in the scandium eluent. If it is less than 1.05 times, the total amount of scandium contained in the scandium eluent may not be recovered, which is not preferable. Exceeding 1.2 times is not preferable because it may lead to an increase in cost and the amount of an oxidizing agent necessary for decomposition of excess oxalic acid, for example, hypochlorous acid soda, increases.

[Washing / Drying / Roasting (Step S22)]
After separating the scandium eluate into a precipitate and a post-precipitation solution, the precipitate is washed with water, dried and roasted. Through this step, extremely high-quality scandium oxide can be obtained.

  The roasting conditions are not particularly limited. For example, the baking may be performed in a tubular furnace and heated at about 900 ° C. for about 2 hours.

  The invention described in this embodiment includes the following inventions.

  (1) A leaching process in which nickel oxide ore containing scandium, aluminum and chromium is charged together with sulfuric acid into a pressure vessel and separated into a leaching solution and a leaching residue under high temperature and high pressure, and a neutralizing agent is added to the leaching solution. In addition, a neutralization step of obtaining a neutralized starch and a post-neutralization solution, a sulfidation step of adding a sulfiding agent to the post-neutralization solution and separating the nickel sulfide and the post-sulfurization solution, and the post-sulfurization solution Contacting the chelate resin having iminodiacetic acid as a functional group to adsorb the scandium to the chelate resin, contacting the chelate resin adsorbing scandium in the adsorption step with 0.1 N or less sulfuric acid, An aluminum removal step for removing aluminum adsorbed on the chelate resin in the adsorption step, and a sulfuric acid of 1N or more and less than 3N in contact with the chelate resin that has undergone the aluminum removal step, A scandium elution step of obtaining an indium eluate, and a chromium removal step of contacting the chelate resin having undergone the scandium elution step with sulfuric acid of 3N or more to remove chromium adsorbed on the chelate resin in the adsorption step. Collection method.

  (2) A neutralizing agent is added to the scandium eluent to adjust the pH to a range of 2 to 4, then a reducing agent is added, and then sulfuric acid is added to a pH of 1 to 2.5. The scandium eluent solution after pH adjustment is obtained by adjusting to the above, and the adsorption step, the aluminum removal step, and the scandium elution step are performed again using this pH adjusted solution, and the scandium recovery according to (1) Method.

  (3) A solution after the pH adjustment of the scandium eluate is obtained, and the cycle of performing the adsorption step, the aluminum removal step, and the scandium elution step is repeated using the pH adjustment solution, and the scandium elution solution according to (2) Collection method.

  (4) An alkali is added to the scandium eluent to separate a precipitate and a post-precipitation solution, and then the precipitate is dried and roasted to obtain scandium oxide. (1) to (3) The method for recovering scandium according to any one of the above.

  (5) Oxalic acid is added to the scandium eluent to separate a precipitate and a post-precipitation solution, and then the precipitate is dried and baked to obtain scandium oxide. (1) to (3 ). The method for recovering scandium according to any one of the above.

  (6) The scandium recovery method according to any one of (1) to (5), wherein the chelate resin that has passed through the chromium removal step is used again in the adsorption step.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention does not receive a restriction | limiting at all in these description.

<Preliminary test> Relationship between pH of sulfuric acid and amount of metal adsorbed on chelate resin

  In order to investigate the relationship between the pH of sulfuric acid and the amount of metal adsorbed on the chelate resin, the metal special grades listed in Table 1 were dissolved in 0.1 to 3N sulfuric acid, and the solution was functionalized with iminodiacetic acid. The solution was passed through a column packed with a chelate resin (product name: Diaion CR11, manufactured by Mitsubishi Chemical Corporation). The amount of resin was 4 ml, and the flow rate was 0.53 ml / min so that the SV was 8, and the flow rate was 240 ml (Bed Volume: BV = 60). There are four types of metals, scandium (Sc), aluminum (Al), chromium (Cr), and iron (Fe), and the metal concentrations in the solution are 0.3 mmol / L, 0.1 mol / L, and 0.01 mol, respectively. / L, 0.03 mol / L. The solution after dissolving in concentrated sulfuric acid is adjusted to six types of pH 0.5, 1.0, 1.5, 2.0, 3.0, 4.0 by adding slaked lime. The solution was passed through the column. The liquid temperature was 60 ° C.

  The amount of adhesion to the chelate resin at this time was calculated by measuring the amount of the eluent and the concentration of the metal contained in the eluent. The results are shown in FIG. The horizontal axis of FIG. 2 indicates the pH of the metal-containing solution that has passed therethrough, and the vertical axis (left) indicates the amount of metal adsorbed on 1 liter of chelate resin (unit: mmol / L). The vertical axis (right) in FIG. 2 shows the ratio of the amount of scandium adsorbed to the amount of impurities adsorbed. For example, Sc / Al represents the ratio of the amount of scandium adsorbed to the amount of aluminum adsorbed, Sc / Cr represents the ratio of the amount of scandium adsorbed to the amount of chromium adsorbed, and Sc / Fe represents the amount of iron adsorbed. The ratio of scandium adsorption is shown.

  According to FIG. 2, it can be seen that a suitable pH for adsorbing to the chelate resin varies depending on the type of metal. For example, if the metal is iron, it is easily adsorbed to the chelate resin at a relatively high pH, and if the metal is aluminum, then the metal is easily adsorbed to the chelate resin at a high pH, and the metal is scandium. If the metal is aluminum, it is easy to adsorb to the chelate resin at the next highest pH, and if the metal is chromium, it is easy to adsorb to the chelate resin at the lowest pH.

  From this, it is possible to remove impurities from the chelate resin appropriately and efficiently recover scandium after passing through the sulfuric acid solution having different pHs stepwise through the chelate resin after the adsorption step S4. Inferred.

<Example 1> Removal of chromium adsorbed on chelate resin [leaching step S1]
First, nickel oxide ore is charged into an autoclave together with concentrated sulfuric acid, and a slurry containing valuable metals such as scandium and nickel is produced over one hour under the condition of 245 ° C., and a leachate containing the valuable metals from this slurry. And solid-liquid separation into leaching residue.

[Neutralization step S2]
And calcium carbonate was added to this leachate, pH was adjusted to the range of 1-4, and the neutralized starch and the liquid after neutralization were obtained. Valuable metals such as scandium and nickel are contained in the solution after neutralization, and most of impurities such as aluminum are contained in the neutralized starch.

[Sulfurization step S3]
Subsequently, hydrogen sulfide gas was blown into the liquid after neutralization, and nickel, cobalt, and zinc were separated from the liquid after sulfidation as sulfides.

[Adsorption process S4]
Slaked lime was added as a neutralizing agent to this post-sulfurized solution to adjust the pH to 1.6. The composition of this adsorbent is: Ni: 0.036 g / l, Mg: 6.5 g / l, Mn: 2.8 g / l, Fe: 1 g / l, Al: 2.3 g / l, Cr: 0.037 g / L, Sc: 0.014 g / l. Next, the adsorbed liquid was passed through a column packed with the chelate resin CR11 type. The amount of resin was 4 ml, and the flow rate was 0.53 ml / min so that the SV was 8, and the flow rate was 240 ml (Bed Volume: BV = 60). The liquid temperature was 60 ° C.

[Aluminum removal step S5]
Next, 80 ml of a sulfuric acid solution having a concentration of 0.1 N was passed through this chelate resin at a flow rate of 2.7 ml per minute (SV becomes 40). The remaining aluminum-rich cleaning solution discharged from the column was stored as an aluminum cleaning solution, a part of which was sampled and analyzed by ICP.
The analysis values were Ni: 7 mg / l, Mg: 1 mg / l, Mn: 4 mg / l, Fe: 1 mg / l, Al: 84 mg / l, Sc: 3 mg / l. Cr and Ca were below the lower limit.

[Scandium elution step S6]
Thereafter, 40 ml of a sulfuric acid solution having a concentration of 1N was passed through the chelate resin (SV becomes 40) at a flow rate of 8 ml per minute. The eluent discharged from the column was stored as a scandium eluent, sampled and analyzed.
The analysis values were Ni: 5 mg / l, Fe: 126 mg / l, Al: 4 mg / l, Cr: 10 mg / l, Sc: 43 mg / l. Mn and Ca were below the lower limit. The scandium quality simply calculated is 67%.

[Chromium removal step S7]
Finally, 80 ml of 3N sulfuric acid solution was passed through the chelate resin at a flow rate of 2.6 ml per minute (SV was 40). The cleaning liquid discharged from the column was stored as a chromium cleaning liquid, sampled and analyzed.
The analytical values were Fe: 2 mg / l, Cr: 30 mg / l. Ni, Mg, Mn, Al, Ca, and Sc were below the lower limit.

[Reuse of chelate resin after chromium removal step S7]
The chelate resin after the chromium cleaning was washed by flowing 40 ml of water at a flow rate of 2.6 ml per minute, and repeated use for the adsorption treatment S4 was repeated a plurality of times. As a result, it was confirmed that even when used repeatedly in the adsorption treatment S4, high-quality scandium can be recovered to the same extent as when it is replaced with a new chelate resin.

<Comparative example>
Steps S1 to S6 were performed under the same conditions as in Example 1 except that the chromium removal step S7 was not performed. The chelate resin was reused under the same conditions as in Example 1. However, since chromium was not sufficiently eluted from the chelate resin, the amount of scandium adsorbed on the chelate resin was lower than that in Example 1, and the quality of recovered scandium was lower than that in Example 1.

<Example 2> Re-adsorption of the scandium eluent obtained in the scandium elution step S6 The pH of the scandium eluate obtained in Example 1 was adjusted to 3, and then the redox potential was a value using the silver-silver chloride electrode as a reference electrode. Then, a reducing agent was added so as to be −200 mV or less, and then adjusted with sulfuric acid so that the pH was in the range of 1 to 2.5.

  Next, scandium eluent was passed through 4 ml of the same type of chelate resin as in Example 1 under the same conditions as in Example 1, and then the same 0.1N, 1N, and 3N sulfuric acid solution as in Example 1 Washing and elution were respectively carried out to obtain a resorbed aluminum cleaning solution, a resorbed scandium eluent, and a resorbed chromium eluent.

The composition of the re-adsorbed aluminum cleaning solution was 3 mg / l for Al and 0.24 g / l for Sc, and all the other elements mentioned above were below the lower limit.
The composition of the re-adsorbed scandium eluent was 1 mg / l for Fe and 0.4 g / l for Sc, and other than that, the lower limit. A scandium quality of 99.8% was obtained.
The composition of the resorbed chromium eluent was 1 mg / l for both Fe and Sc, and all other elements were below the lower limit.
It was confirmed that the re-adsorption improves the quality of scandium.

<Example 3> Purification of scandium eluent The scandium eluent was purified by repeating the scandium elution step S6 a plurality of times. That is, the scandium eluate obtained in the scandium elution step S6 was again subjected to the scandium elution step S6, and after increasing the concentration of scandium, the composition of the scandium eluent was measured again.

  The result at this time is shown in FIG. The horizontal axis in FIG. 3 indicates the number of times that the scandium elution step S6 is repeated, and the vertical axis indicates the concentration of scandium contained in the scandium eluent after the repetition. In addition, the dotted line of FIG. 3 is an approximate line by the least square method. According to FIG. 3, the more the scandium elution step S6 is repeated, the higher the concentration of recovered scandium. However, even if it is excessively repeated, the degree of increase in the concentration of recovered scandium is reduced. It can be seen that the number of times of repeating the scandium elution step S6 is preferably 8 or less.

<Example 4> Addition of oxalic acid to scandium eluent A sodium hydroxide solution was added to the scandium eluent obtained by the same method as in Example 1 above, and the pH was maintained in the range of 8 to 9 to scandium hydroxide. Precipitate was produced. Washed with pure water, separated into solid and liquid, then added hydrochloric acid to the collected scandium hydroxide precipitate and stirred while maintaining the pH of the slurry in the range of 1.0 to 1.5. Was completely dissolved to obtain a redissolved solution.

  Next, in the redissolved solution, oxalic acid dihydrate (Mitsubishi Gas Co., Ltd.) crystals, which are twice the calculated amount of scandium contained in the redissolved solution, are dissolved and mixed with stirring for 60 minutes. This produced a white crystalline precipitate of scandium oxalate. The produced white crystalline precipitate is filtered by suction, washed with pure water, dried at 105 ° C. for 8 hours, put in a tubular furnace and maintained at 850 to 900 ° C. to be baked, whereby scandium oxide Got.

  Subsequently, scandium oxide was roasted in the same manner as in Example 1 and analyzed by emission spectroscopy. As a result, the impurity quality was 10 ppm for nickel, 20 ppm for iron, 10 ppm for aluminum, and 10 ppm for chromium, and it was confirmed that the obtained scandium oxide was extremely high quality.

Claims (1)

  Contact the chelating resin with iminodiacetic acid as a functional group and adsorbed scandium, aluminum and chromium with 0.1N or less sulfuric acid, remove aluminum from the chelating resin, and then add 1N or more and less than 3N sulfuric acid to the chelating resin. A method for recovering scandium, which is brought into contact to obtain a scandium eluent.

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