JP7276043B2 - Scandium recovery method and ion exchange treatment method - Google Patents

Description

The present invention relates to a scandium recovery method and an ion exchange treatment method applied to the recovery method.

Scandium (Sc) is extremely useful as an additive for high-strength aluminum alloys and as an electrode material for fuel cells. However, its use was limited due to its low production volume and high cost.

By the way, it is known that nickel oxide ores represented by laterite ore and limonite ore contain a small amount of scandium. However, since the nickel oxide ore has a low nickel-containing grade, there is a problem that the recovery of nickel is costly. For this reason, it can only be used as a raw material for stainless steel by subjecting it to pyrometallurgical refining in which it is melted at a high temperature in a furnace to obtain ferronickel, which is an alloy of iron and nickel.

When nickel oxide ore is processed using the pyrometallurgical method, scandium is separated from nickel, but it is distributed into slag, which is a chemically stable form, along with many impurities, so scandium can be recovered in high purity. is technically difficult to do. Therefore, almost no research has been conducted to industrially recover scandium contained in nickel oxide ore.

However, in recent years, high-pressure acid leaching (High Pressure Leaching) is performed by charging nickel oxide ore together with sulfuric acid into a pressurized vessel and heating it to a high temperature of about 240 ° C to 260 ° C to separate solid and liquid into a leach solution containing nickel and a leach residue. Acid Leach (HPAL) process has been industrially put into practical use (see, for example, Patent Document 1).

In this HPAL process, a neutralizing agent is added to the leachate obtained from the leaching process to separate impurities, and then a sulfiding agent is added to recover nickel as nickel sulfide. Then, by treating the recovered nickel sulfide in an existing nickel refining process, a nickel salt compound such as electrolytic nickel or nickel sulfate can be obtained.

When such an HPAL process is used, the scandium contained in the nickel oxide ore is contained in the leachate together with nickel. Then, a neutralizing agent is added to the resulting leachate to separate impurities, and then a sulfiding agent is added to perform a sulfidation treatment. Nickel is recovered as nickel sulfide, while scandium is recovered as a sulfiding agent. It comes to be included in the acidic solution (post-sulfidation solution) after the addition. Therefore, nickel and scandium can be effectively separated by using the HPAL process.

However, the scandium separated by the HPAL process is dilute and contains a wide variety of impurities, so further purification is required to concentrate and recover the scandium by separating it from the impurities. This purification treatment is reported, for example, in Patent Document 2 as a method using a chelate resin.

Specifically, in the method disclosed in Patent Document 2, first, nickel and scandium are selectively leached into an acidic aqueous solution from nickel oxide ore under high temperature and high pressure in an oxidizing atmosphere to obtain an acidic solution. The pH of the acid solution is adjusted to a range of 2-4 to selectively precipitate and recover nickel as sulfide by use of a sulfiding agent. Next, the obtained solution after nickel recovery (solution after sulfurization) is brought into contact with a chelate resin to adsorb scandium, the chelate resin is washed with a dilute acid, and after washing, the chelate resin is brought into contact with a strong acid. It is to elute scandium.

It is known that the impurities contained in nickel oxide ore include elements such as iron, aluminum, chromium, manganese, and magnesium, although the types and amounts vary depending on the region of production. .

In particular, chromium contained in nickel oxide ore behaves similarly to scandium and is easily adsorbed by chelate resins, but it is difficult to elute unless high-concentration sulfuric acid is used to elute scandium. .

Therefore, Patent Document 3 discloses a method of eluting chromium from a chelate resin using a sulfuric acid solution having a higher concentration than the sulfuric acid solution used for eluting scandium.

Specifically, in Patent Document 3, ion exchange treatment using a chelate resin is performed on a post-sulfidation liquid obtained by hydrometallurgical treatment using nickel oxide ore containing scandium, aluminum, and chromium as a raw material. A scandium recovery method with an exchange step is disclosed. In the ion exchange step, the post-sulfurization solution is brought into contact with a chelate resin to adsorb scandium onto the chelate resin, and the scandium elution step is carried out to bring the chelate resin into contact with sulfuric acid of 0.3 N or more and less than 3 N to obtain a scandium eluate. and a chromium removing step of contacting the chelating resin that has undergone the scandium elution step with 3N or higher sulfuric acid to remove chromium adsorbed on the chelating resin.

That is, in the method disclosed in Patent Document 3, the impurity element chromium is also adsorbed on the chelate resin together with scandium, and the difference in concentration of the sulfuric acid solution used for elution is used to extract scandium in a state where chromium is adsorbed on the chelate resin. eluted from the chelate resin and separated from the chromium.

However, even if chromium is eluted from the chelate resin by such a method, chromium gradually accumulates in the chelate resin as the chelate resin is used repeatedly, and the adsorption of scandium may be hindered by that amount. rice field. As a result, the recovery amount of scandium is reduced, the concentration of scandium eluted from the chelate resin is also reduced, and the scandium concentration process is hindered.

In order to completely elute chromium from the chelate resin, a method of increasing the concentration of the sulfuric acid solution and increasing the amount of solution passing through the solution is considered to have a certain effect on such a problem. However, the use of a large amount of excessively strong acid is not preferable because it increases the cost of using sulfuric acid and damages to the resin. In addition, the treatment of the strongly acidic solution containing chromium after elution from the chelate resin is costly and troublesome.

JP-A-3-173725 JP-A-9-194211 JP 2014-218719 A

The present invention has been proposed in view of such circumstances. An object of the present invention is to provide a method for efficiently concentrating scandium while suppressing a decrease in productivity.

As a result of extensive studies, the present inventors have found that in the ion exchange treatment in which scandium is brought into contact with at least an acidic solution containing scandium and chromium in contact with the chelate resin, the acidity By maintaining the temperature of the solution in a predetermined low temperature range and contacting it, it is possible to suppress the adsorption of chromium to the chelate resin, and by utilizing this, the amount of scandium recovered can be increased, and the present invention has been completed. reached.

(1) A first aspect of the present invention is a method for recovering scandium from an acidic solution containing at least scandium and chromium, wherein scandium in the acidic solution is removed by contacting the acidic solution with a chelate resin. an ion exchange treatment step of adsorbing to a chelate resin and then obtaining a scandium eluate, wherein in the ion exchange treatment step, when the acidic solution is brought into contact with the chelate resin, the temperature of the acidic solution exceeds 20 ° C. A method for recovering scandium in which the temperature is maintained at 50° C. or less and contacted.

(2) A second aspect of the present invention is based on the first aspect, wherein the acidic solution is obtained by subjecting nickel oxide ore to a leaching treatment with sulfuric acid and adding a sulfiding agent to the obtained leaching solution to produce nickel sulfide. This is a method for recovering scandium, which is a solution after separation.

(3) A third aspect of the present invention is the method for recovering scandium according to the first or second aspect, wherein the chelate resin is a resin having iminodiacetic acid as a functional group.

(4) In a fourth aspect of the present invention, in any one of the first to third aspects, the ion exchange treatment step includes bringing the acidic solution into contact with the chelate resin to adsorb scandium on the chelate resin. a step of contacting a chelate resin that has adsorbed scandium with less than 0.3 N sulfuric acid to remove aluminum adsorbed on the chelate resin; A step of contacting and eluting scandium adsorbed on the chelating resin to obtain a scandium eluate, a step of contacting the chelating resin from which scandium has been eluted with 3N or more sulfuric acid to remove chromium adsorbed on the chelating resin; and repeatedly using the chelate resin after removing the chromium in the step of adsorbing the scandium.

(5) A fifth aspect of the present invention is an ion exchange treatment method for obtaining a scandium-enriched solution by subjecting an acidic solution containing at least scandium and chromium to an ion exchange treatment using a chelate resin. comprising a step of causing scandium in the acidic solution to be adsorbed on the chelating resin by bringing the acidic solution into contact with the chelating resin; This is an ion-exchange treatment method in which contact is made while maintaining the temperature in the range of over 20°C to 50°C or less.

According to the present invention, when scandium is recovered from an acidic solution containing at least scandium and chromium through ion exchange treatment using a chelate resin, adsorption of chromium to the chelate resin can be suppressed.

As a result, even when the chelate resin is used repeatedly, the amount of scandium adsorbed to the chelate resin can be prevented from decreasing. As a result, the scandium concentration in the scandium eluate obtained by eluting from the chelating resin can be increased, and high-purity scandium can be recovered, and the amount of scandium recovered can be increased.

It is a process drawing which shows an example of the flow of the recovery|recovery method of scandium. FIG. 4 is a graph showing measurement results of distribution coefficients of scandium and chromium to the chelate resin with respect to the liquid temperature of the post-sulfidation liquid.

Hereinafter, specific embodiments of the present invention (hereinafter referred to as "present embodiments") will be described in detail, but the present invention is not limited to the following embodiments, and the gist of the present invention is changed It can be implemented with appropriate changes within the scope of not doing so. In this specification, the notation "X to Y" (X and Y are arbitrary numerical values) means "X or more and Y or less".

A method for recovering scandium according to the present invention is a method for recovering scandium from an acidic solution containing at least scandium (Sc) and chromium (Cr). For example, the acidic solution includes a solution obtained by subjecting nickel oxide ore to a leaching treatment with sulfuric acid and adding a sulfiding agent to the obtained leaching solution to separate nickel sulfide.

Specifically, this scandium recovery method includes an ion exchange treatment step of bringing an acidic solution into contact with a chelate resin to adsorb scandium in the acidic solution to the chelate resin, and then obtaining a scandium eluate. In the ion exchange treatment step, when the acidic solution is brought into contact with the chelate resin, the temperature of the acidic solution is kept in a relatively low temperature range, specifically in a range of more than 20° C. and 50° C. or less. Characterized by

As described above, in the method for recovering scandium according to the present invention, in the ion exchange treatment step using the chelate resin, the temperature of the acidic solution to be brought into contact with the chelate resin is adjusted so that the contact is maintained at a relatively low temperature. I have to. This makes it possible to suppress adsorption of chromium, in particular, contained in the acidic solution to the chelate resin, and prevent a decrease in the amount of scandium adsorbed to the chelate resin even when the chelate resin is used repeatedly. As a result, the scandium concentration of the scandium eluate obtained by eluting from the chelate resin can be increased, and the purity of the recovered scandium can be improved. Moreover, the recovery amount of scandium can be increased.

FIG. 1 is a process diagram showing an example of the flow of a scandium recovery method. This example shows the flow of recovering scandium from the post-sulfidation liquid, which is an acidic solution obtained through the hydrometallurgical process of nickel oxide ore. The post-sulfidation liquid contains at least scandium and chromium.

As shown in FIG. 1, the scandium recovery method includes a hydrometallurgical treatment step S1 in which a nickel oxide ore hydrometallurgical process is performed to generate nickel sulfide and a post-sulfided liquid, and a hydrometallurgical treatment step S1. and an ion exchange treatment step S2 for obtaining a scandium eluate by subjecting the acidic solution obtained from (1) to an ion exchange treatment, and a scandium recovery step S3 for recovering scandium from the scandium eluate. It is also possible to have a re-adsorption treatment step S4 for re-adsorbing the scandium eluate to the chelate resin.

(1) Hydrometallurgical processing step As the acidic solution containing scandium to be processed for recovery of scandium, as described above, nickel oxidation such as a sulfuric acid acidic solution obtained by leaching nickel oxide ore with sulfuric acid A solution obtained through hydrometallurgical processing of ore can be used.

Specifically, as the acidic solution containing scandium, the nickel oxide ore is leached with sulfuric acid under high temperature and high pressure to obtain a leachate (S11), and a neutralized precipitate containing impurities is added to the leachate by adding a neutralizing agent to the leachate (S11). and a neutralization step S12 in which a post-neutralization solution is obtained, and a sulfurization step S13 in which a sulfurizing agent is added to the post-neutralization solution to obtain nickel sulfide and a post-sulfuration solution. A post-sulfidation solution can be used. The flow of the hydrometallurgical treatment step S1 will be briefly described below.

(Leaching process)
In the leaching step S11, for example, using a high-temperature pressurized container (autoclave) or the like, sulfuric acid is added to a slurry of nickel oxide ore and stirred at a temperature of 240° C. to 260° C. to form a leaching solution and a leaching residue. 2. Forming a leach slurry. The treatment in the leaching step S11 may be performed according to the conventionally known HPAL process.

Nickel oxide ores mainly include so-called laterite ores such as limonite ores and saprolite ores. The nickel content of laterite ores is typically 0.8% to 2.5% by weight and is contained as a hydroxide or magnesium silicate (magnesium silicate) mineral. Also, these nickel oxide ores contain scandium.

In the leaching step S11, while washing the leaching slurry composed of the obtained leaching solution and leaching residue, solid-liquid separation into the leaching solution containing nickel, cobalt, scandium, etc. and the leaching residue, which is hematite, is performed. In the solid-liquid separation process, for example, after the leach slurry is mixed with the cleaning liquid, a flocculant supplied from a flocculant supply facility or the like can be used and a solid-liquid separation facility such as a thickener can be used.

(Neutralization process)
The neutralization step S12 is a step of adding a neutralizing agent to the resulting leachate to adjust the pH, thereby obtaining a neutralized sediment containing impurity elements and a post-neutralization solution. Due to the neutralization treatment in the neutralization step S12, valuable metals such as nickel, cobalt and scandium are contained in the post-neutralization liquid, and most of the impurities including iron and aluminum become neutralized precipitates.

Conventionally known neutralizing agents can be used, and examples thereof include calcium carbonate, slaked lime and sodium hydroxide.

(Sulfurization process)
The sulfurization step S13 is a step of adding a sulfurizing agent to the post-neutralization solution obtained in the neutralization step S12 to obtain a nickel sulfide and a post-sulfuration solution. Nickel, cobalt, zinc and the like are converted into sulfides by the sulfurization treatment in the sulfurization step S13, and scandium is included in the post-sulfuration solution.

Specifically, in the sulfiding step S13, a sulfiding agent such as hydrogen sulfide gas, sodium sulfide, or sodium sulfide hydrosulfide is added to the obtained post-neutralization liquid to obtain a sulfide containing nickel and cobalt with few impurity components. (hereinafter also simply referred to as "nickel sulfide") and a post-sulfidation solution that stabilizes the nickel concentration at a low level and contains scandium.

In the sulfurization treatment in the sulfurization step S13, slurry containing nickel sulfide is subjected to a sedimentation separation treatment using a sedimentation separation device such as a thickener, and the nickel sulfide is separated and recovered from the bottom of the thickener. On the other hand, the post-sulfidation solution containing scandium, which is an aqueous solution component, is recovered by overflowing.

In the scandium recovery method, the post-sulfidation solution obtained through each step of the nickel oxide ore hydrometallurgical treatment step S1 as described above is subjected to the scandium recovery treatment, and is an acidic solution containing at least scandium and chromium. It can be used as a solution.

(2) Ion exchange treatment step In the ion exchange treatment step S2, scandium is a step of obtaining a scandium eluate in which the is concentrated.

The post-sulfidation solution, which is an acidic solution containing scandium, contains, in addition to scandium, at least impurities such as chromium that remain in the solution without being sulfurized in the sulfurization treatment in the sulfurization step S15 described above. For this reason, when recovering scandium from the post-sulfurization liquid, it is preferable to remove impurities contained in the post-sulfurization liquid in advance to concentrate scandium.

The ion exchange treatment step S2 includes, for example, an adsorption step S21 in which the post-sulfidation solution is contacted with a chelate resin to adsorb scandium, and an adsorption step S21 in which the chelate resin that has adsorbed scandium is brought into contact with a predetermined normality of sulfuric acid to remove aluminum. An aluminum removal step S22, a scandium elution step S23 in which a chelating resin is contacted with sulfuric acid having a predetermined normality to obtain a scandium eluate, and a chelating resin is contacted with sulfuric acid having a predetermined normality to remove chromium adsorbed on the chelating resin. and a chromium removal step S24 to remove can be exemplified.

The type of chelate resin used for ion exchange treatment is not particularly limited. For example, a resin having iminodiacetic acid as a functional group can be used, and such a chelate resin can enhance scandium adsorption selectivity. Alternatively, for example, a chelate resin may be packed in a column, and an acidic solution may be passed through the column to bring it into contact with the chelate resin, thereby causing the chelate resin to adsorb scandium.

(adsorption process)
In the adsorption step S21, for example, a column is filled with a chelate resin, and a post-sulfidation solution, which is an acidic solution, is passed through the column to bring the acidic solution into contact with the chelate resin, thereby adsorbing scandium in the solution onto the chelate resin. . As the chelate resin, as described above, for example, a resin having iminodiacetic acid as a functional group can be used.

Here, in the method for recovering scandium according to the present invention, in the adsorption step S21, when the acidic solution is brought into contact with the chelate resin to adsorb scandium, the acidic solution is brought into contact while being adjusted and maintained within a predetermined temperature range. . Specifically, it is characterized in that the temperature of the acidic solution is kept above 20° C. and below 50° C., and brought into contact with the chelate resin.

When trying to recover scandium from the post-sulfidation liquid obtained through the hydrometallurgical treatment step S1 by the HPAL process as described above, the liquid temperature of the post-sulfidation liquid at the time of passing through the chelate resin is 60 ° C. ~ A relatively high temperature of about 80° C. is common. This is because the pressure leaching (treatment in the leaching step S11) in the hydrometallurgical treatment step S1 is performed at a high temperature of about 240°C to 250°C, and the solubility in the solution must be maintained as high as possible. This is because there is no need to provide a cooling facility in order to make the facility compact.

With respect to such a general temperature range, in the recovery method according to the present invention, the liquid temperature of the post-sulfuration liquid to be brought into contact with the chelate resin is lowered to 50°C or lower, preferably 40°C or lower, and then the chelate resin is brought into contact with the liquid. I am trying to let More specifically, the temperature of the post-sulfidation liquid is lowered from the conventional general range of 60°C to 70°C to 50°C or less using cooling equipment, a heat exchanger, or the like, and the temperature range is reduced. while maintaining contact with the chelating resin.

According to such a method, the adsorption amount of chromium ions contained in the post-sulfidation solution to the chelate resin can be reduced, and the adsorption amount of scandium ions can be increased accordingly.

Specifically, the adsorption rate of scandium exceeds 90% by contacting the chelate resin while maintaining the liquid temperature of the post-sulfidation liquid, which is an acidic solution, at 50°C. Moreover, when contact is made while maintaining the liquid temperature preferably at 40° C. or less, scandium is adsorbed at an adsorption rate of approximately 100%. For this reason, the amount of scandium recovered by elution from the chelate resin can be increased extremely effectively, which is preferable.

Further, even when the chelate resin from which chromium has been removed in the later-described chromium removal step S24 is repeatedly used again in the adsorption step S21, it is possible to suppress a decrease in the amount of scandium adsorbed. As a result, the scandium concentration in the scandium eluate obtained by eluting from the chelating resin can be increased, and high-purity scandium can be recovered, and the amount of scandium recovered can be increased.

In addition, since the amount of chromium adsorbed to the chelate resin can be suppressed in this way, there is no need to remove chromium using, for example, a high-concentration sulfuric acid solution, thereby suppressing damage to the chelate resin and extending its life. can be done.

Although the temperature of the acidic solution is maintained at a relatively low temperature, it is, of course, not preferable to set it to a temperature that causes it to freeze or become supersaturated and crystallize during passage of the solution. In addition, when deposits of calcium or the like called scaling occur, the chelate resin and facilities such as piping are damaged, and it takes time and effort to remove the deposits. Therefore, considering practical handling, the temperature is preferably above 20°C, preferably room temperature, that is, 25°C as the lower limit, and more preferably 30°C as the lower limit.

(Aluminum removal step)
In the aluminum removal step S22, the chelate resin that has adsorbed scandium in the adsorption step S21 is brought into contact with sulfuric acid of less than 0.3N to remove aluminum adsorbed on the chelate resin. When aluminum is removed from the chelate resin with sulfuric acid, a solution (aluminum eluate) in which aluminum is eluted is recovered.

When removing aluminum, the pH of the sulfuric acid brought into contact with the chelating resin is preferably maintained in the range of 1.0 to 2.5, more preferably in the range of 1.5 to 2.0. If the pH of the sulfuric acid is less than 1.0, not only aluminum but also adsorbed scandium may be removed from the chelating resin. On the other hand, if the pH of sulfuric acid exceeds 2.5, aluminum may not be properly removed from the chelating resin. Therefore, the sulfuric acid concentration should be less than 0.3N, preferably about 0.1N to 0.2N.

(Scandium elution step)
In the scandium elution step S23, the aluminum-removed chelate resin is brought into contact with 0.3 N or more and less than 3.0 N sulfuric acid to elute scandium from the chelate resin to obtain a scandium eluate.

When obtaining the scandium eluate, it is preferable to maintain the normality of the sulfuric acid used in the eluent (solution for elution) in the range of 0.3N or more and less than 3.0N, and 0.5N or more and less than 2.0N. It is more preferable to keep it within range. When the normality is 3.0 N or more, not only scandium but also chromium as an impurity adsorbed on the chelate resin may be eluted and included in the scandium eluate. On the other hand, when the normality is less than 0.3N, scandium is not appropriately eluted from the chelating resin, which is not preferable.

The scandium eluate obtained from the scandium elution step S23 may be repeatedly used, that is, the scandium eluate may be brought into contact with the chelate resin again to repeat the scandium elution step S23 (scandium eluate purification). Thereby, the concentration of scandium contained in the scandium eluate can be increased.

(Chromium removal step)
In the chromium removal step S24, the chelate resin from which scandium has been eluted through the scandium elution step S23 is brought into contact with sulfuric acid of 3.0 N or higher to remove chromium, which is an impurity adsorbed on the chelate resin. When chromium is removed from the chelate resin with sulfuric acid, a solution in which chromium is eluted (chromium eluate) is recovered.

When removing chromium, the normality of sulfuric acid is preferably 3.0N or more. If the normality of sulfuric acid is less than 3.0N, chromium may not be properly removed from the chelate resin.

Here, the chelate resin after removing the chromium adsorbed on the chelate resin in the chromium removal step S24 can be reused as the chelate resin for adsorbing scandium by repeating the adsorption step S21 described above.

As described above, in the recovery method according to the present invention, the liquid temperature of the post-sulfidation liquid, which is an acidic solution, is kept at a relatively low temperature of more than 20°C and 50°C or less, so that it contacts the chelate resin. Therefore, the adsorption amount of chromium can be suppressed. As a result, almost no chromium remains in the chelate resin recovered through the chromium removal step S24. Therefore, even when the chelate resin after removing chromium is repeatedly used, chromium is not gradually accumulated, and the decrease in the amount of scandium adsorbed can be effectively prevented.

In addition, since the chelate resin can be effectively used repeatedly in this manner, the scandium recovery treatment can be economically and efficiently carried out, which is preferable.

(Iron removal step)
Moreover, although not shown, an iron removal step for removing iron as an impurity may be provided prior to the above-described aluminum removal step S22. The post-sulfidation solution may contain iron derived from nickel oxide ore as a raw material. In such a case, from the viewpoint of reducing impurities and increasing the scandium concentration in the scandium eluate, it is preferable to provide an iron removal step to remove iron adsorbed on the chelate resin.

Specifically, the iron removal step is provided as a step before the aluminum removal step S22. Removes adsorbed iron. When removing iron, the pH of sulfuric acid is preferably maintained in the range of 1.0 to 3.0. If the pH of the sulfuric acid is less than 1.0, not only iron but also scandium may be removed from the chelating resin, while if the pH of the sulfuric acid is greater than 3.0, the iron is adequately removed from the chelating resin. may not be removed.

(3) Scandium recovery step The scandium recovery step S3 is a step of recovering scandium from the scandium eluate obtained through the ion exchange treatment step S2. For example, scandium can be recovered in the form of scandium oxide.

The treatment method in the scandium recovery step S3 is not particularly limited, and a known method can be used. For example, a method of recovering as precipitates of scandium hydroxide by adding an alkali to the scandium eluent and neutralizing it, or a method of adding oxalic acid to the scandium eluent and recovering it as oxalate precipitates. (oxalation treatment) can be used. Among others, impurities can be separated more effectively by a method using oxalation treatment.

Specifically, in the recovery method using oxalation treatment, oxalic acid is added to the scandium eluate to form a precipitate of scandium oxalate, and then the scandium oxalate is dried and roasted to oxidize. Recovered as scandium. In addition, in the oxalation treatment, a precipitate of scandium oxalate may be formed by adding extraction residue to a reaction tank containing an oxalic acid solution.

The roasting treatment is, for example, a treatment in which the precipitate of scandium oxalate obtained by oxalation treatment is washed with water, dried, and then roasted. Through this roasting treatment, scandium can be recovered as extremely high-purity scandium oxide. The roasting treatment conditions are not particularly limited, but, for example, they may be placed in a tubular furnace and heated at about 900° C. for about 2 hours.

Although not shown, prior to the scandium recovery step S3, the scandium eluate obtained through the ion exchange treatment step S2 may be subjected to a solvent extraction treatment (solvent extraction step). By performing the solvent extraction treatment in this way, for example, impurities contained in the scandium eluate can be selectively extracted into an organic solvent containing an extractant, and the scandium eluate can be purified, thereby concentrating scandium. A solution (residue) can be obtained.

(4) Re-adsorption treatment step Although not an essential aspect, a re-adsorption treatment may be performed to cause the scandium eluent obtained through the ion exchange treatment step S2 to be re-adsorbed to the chelate resin (re-adsorption treatment). adsorption treatment step S4).

Specifically, as a treatment for the scandium eluate for re-adsorption of the chelate resin, for example, a neutralizing agent is added to the scandium eluate to adjust the pH to a range of 2.0 or more and 4.0 or less, preferably pH 3.0. The pH is adjusted to the range of 2.7 to 3.3 centered on 0, then a reducing agent is added, and then sulfuric acid is added to adjust the pH to a range of 1.0 or more and 2.5 or less, preferably pH 2.5. Processing is performed to adjust the range from 1.7 to 2.3 with 0 as the center. The ion exchange treatment step S2 (adsorption step S21, aluminum removal step S22, scandium elution step S23) is performed again using the solution after adjusting the pH in this way (the solution after pH adjustment).

In this way, the obtained scandium eluate is subjected to re-adsorption treatment, and the treated solution (pH-adjusted solution) is repeatedly subjected to the ion exchange treatment step S2 to be re-adsorbed to the chelate resin. It is possible to further improve the quality of scandium contained in the steel. In addition, it is possible to reduce the chemical cost and the scale of equipment when separating scandium from the scandium eluate.

Here, as the neutralizing agent, a conventionally known one can be used, and examples thereof include calcium carbonate. Also, conventionally known reducing agents can be used, and examples thereof include sulfurizing agents such as hydrogen sulfide gas and sodium sulfide, sulfur dioxide gas, hydrazine, metallic iron, and the like.

The addition of the reducing agent is preferably carried out so that the oxidation-reduction potential (ORP) is maintained in the range of more than 200 mV to 300 mV or less with a silver/silver chloride electrode as a reference electrode. For example, when a sulfiding agent is used as a 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, clogging the filter cloth in the filtration process after sulfurization. This may cause deterioration of solid-liquid separation, resulting in a decrease in productivity. In addition, when the liquid is passed through the chelate resin again, clogging or uneven flow of the liquid may occur in the column, which may cause problems such as inability to pass the liquid uniformly. On the other hand, when the redox potential exceeds 300 mV for all reducing agents, residual iron ions and the like may be adsorbed on the chelate resin, which may cause problems such as inhibition of scandium adsorption.

When the scandium eluate is re-adsorbed onto the chelate resin, the chelate resin that has already been used may be reused, or a new chelate resin may be used. From the viewpoint of preventing contamination with impurities, it is preferable to reuse the chelate resin recovered through the chromium removal step S24, or to use a new chelate resin. In particular, by reusing the chelate resin recovered through the chromium removal step S24, it is possible not only to prevent contamination with impurities, but also to reduce the amount of chelate resin used.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[Test Example 1: Verification of liquid temperature of post-sulfurization liquid brought into contact with chelate resin]
The nickel oxide ore is subjected to a hydrometallurgical treatment based on the HPAL process to recover nickel, and the post-sulfidation solution, which is an acidic solution obtained, is brought into contact with a chelate resin having iminodiacetic acid as a functional group, and the sulfurization is performed. After that, an ion exchange treatment was performed to adsorb scandium in the liquid to the chelate resin. The post-sulfidation solution contained at least scandium and chromium.

At this time, when the post-sulfurization liquid was brought into contact with the chelate resin, the temperature of the post-sulfurization liquid was adjusted to and maintained at a predetermined temperature. Specifically, 1 L of the post-sulfurization liquid was put into a beaker, and the temperature of the post-sulfurization liquid (liquid temperature) was controlled at 30°C to 60°C. 30 ml of a chelate resin was added thereto, and the post-sulfuration liquid was brought into contact therewith by batch processing to adsorb scandium.

By such treatment, the concentration of each element before and after adsorption was measured, and the distribution coefficient between scandium and chromium was obtained from the following formula [1].
Partition coefficient = target element concentration in resin (mg/L)/target element concentration in liquid after adsorption (mg/L)
Formula [1]

FIG. 2 shows the measured results of the distribution coefficient of scandium and chromium to the chelate resin, that is, the relationship of the temperature dependency with respect to the liquid temperature of the post-sulfidation liquid. In addition, it shows that it is easy to adsorb|suck to a chelate resin, so that a distribution coefficient is large.

As can be seen from the graph in FIG. 2, the higher the temperature of the post-sulfidation liquid brought into contact with the chelate resin, the higher the amount of chromium adsorbed on the chelate resin, while the amount of scandium adsorbed gradually decreases. rice field. In particular, when the liquid temperature of the post-sulfidation liquid exceeds 50° C., it can be seen that the adsorption amount of chromium increases sharply.

Based on these results, when an acidic solution containing at least scandium and chromium is brought into contact with a chelate resin to adsorb scandium, the liquid temperature of the liquid after sulfurization (liquid temperature at the time of adsorption) is adjusted to 50° C. or less. Thus, it was confirmed that adsorption of chromium to the chelate resin could be effectively suppressed.

Note that the higher the liquid temperature, the more chromium is adsorbed, and the amount of scandium adsorbed tends to decrease. This means that when the elution of chromium from the chelate resin becomes insufficient in the chromium removal step (step S24 in FIG. 1), even if the chelate resin is repeatedly used to adsorb scandium again, the chelate resin It is believed that the remaining chromium reduces the sites where scandium can be adsorbed, resulting in a significant reduction in scandium adsorption.

[Test Example 2: Verification of the relationship between the liquid temperature of the post-sulfidation liquid and the amount of scandium recovered]
Subsequently, the effect of liquid temperature on the amount of scandium recovered was examined.

Specifically, the post-sulfurization liquid obtained through the hydrometallurgical treatment is passed through a column filled with 0.5 liters of a chelate resin having iminodiacetic acid as a functional group in a liquid volume of 10 liters, thereby sulfiding. The subsequent liquid was brought into contact with a chelate resin to adsorb scandium. Next, a sulfuric acid solution having a concentration of 0.5 N was passed through the chelating resin to elute scandium.

After scandium was eluted, chromium was eluted using a sulfuric acid solution having a concentration of 5N corresponding to one volume of the chelate resin. Further, after the chromium was eluted, the resin was washed with pure water to remove the sulfuric acid solution remaining on the resin.

Such a treatment cycle of adsorption, elution, and washing was repeated 20 times, and the adsorption rate of scandium in each batch was investigated. The adsorption rate is defined by the following formula [2], and the average scandium adsorption rate of 20 cycles was obtained. A scandium adsorption rate of 90% was used as a criterion for acceptance in industrial operations.
Scandium adsorption rate = (amount of scandium in post-sulfidation liquid - amount of scandium in post-adsorption liquid)/amount of scandium in post-sulfidation liquid Formula [2]

(Example 1)
In Example 1, the liquid temperature of the obtained post-sulfurization liquid was adjusted and maintained at 30° C., and 11000 cc of the post-sulfurization liquid was passed through and brought into contact with 550 cc of the chelate resin having iminodiacetic acid as a functional group. , adsorbed scandium and other impurities in the post-sulfidation solution.

Thereafter, scandium was eluted from the chelating resin using a sulfuric acid solution having a concentration of 0.5N. After scandium was eluted, chromium was eluted using a sulfuric acid solution having a concentration of 5N, and then the chelate resin was washed with water to remove the sulfuric acid solution remaining on the resin.

The average value of the scandium adsorption rate at this time was 99%, and scandium could be adsorbed almost completely.

(Example 2)
In Example 2, the conditions were the same as in Example 1, except that the temperature of the obtained post-sulfurization solution was adjusted and maintained at 40° C. and brought into contact with the chelate resin.

As a result, the average value of the scandium adsorption rate was 99%, and scandium could be adsorbed almost completely.

(Example 3)
In Example 3, the conditions were the same as in Example 1, except that the temperature of the obtained post-sulfurization solution was adjusted and maintained at 50° C. and brought into contact with the chelate resin.

As a result, the average adsorption rate of scandium was 96%.

(Comparative example 1)
In Comparative Example 1, the conditions were the same as in Example 1, except that the temperature of the obtained post-sulfiding solution was adjusted and maintained at 60° C. and brought into contact with the chelate resin.

As a result, the average value of the scandium adsorption rate was 79%, which was much lower than the above-described Examples 1 to 3 and was below the pass/fail criteria.

(Comparative example 2)
In Comparative Example 2, the temperature of the obtained post-sulfidation solution was adjusted and maintained at 60° C. and brought into contact with the chelate resin, and the amount of the sulfuric acid solution used for eluting chromium after eluting scandium was used in Example 1. The conditions were the same as in Example 1, except that the amount of the sulfuric acid solution was doubled.

As a result, the average value of the scandium adsorption rate was 86%, which was much lower than the above-described Examples 1 to 3 and was below the pass/fail criteria. In addition, since a large amount of sulfuric acid solution was used, the treatment was not economically efficient.

(Comparative Example 3)
In Comparative Example 3, the temperature of the obtained post-sulfidation solution was adjusted and maintained at 30° C. and brought into contact with the chelate resin, and the amount of the sulfuric acid solution used for eluting chromium after eluting scandium was used in Example 1. The conditions were the same as in Example 1, except that the amount was 0.5 times that of the sulfuric acid solution.

As a result, the average value of the scandium adsorption rate was 60%, which was much lower than the above-described Examples 1 to 3 and fell below the pass/fail criteria.

As described above, from the results of Examples and Comparative Examples in Test Example 2, it was found that the scandium adsorption rate can be stabilized in a range exceeding 90% by lowering the temperature of the post-sulfiding liquid and bringing it into contact with the chelate resin. rice field. Specifically, it was found that a nearly 100% scandium adsorption rate can be obtained by bringing the liquid into contact with the chelate resin at a liquid temperature of 50° C. or lower, particularly 40° C. or lower. In addition, by lowering the liquid temperature of the post-sulfidation liquid and bringing it into contact with the chelate resin, the amount of chromium adsorbed is reduced, and at the same time, by eluting chromium sufficiently, the adsorption rate of scandium to the chelate resin is stabilized. I also found that I could keep it higher.

It was confirmed that the sulfuric acid solution used for eluting chromium from the chelate resin needs not only the concentration but also the volume of the chelate resin (one time) or more.

Claims (5)

In a method for recovering scandium from an acidic solution containing at least scandium and chromium,
contacting the acidic solution with the chelating resin to adsorb scandium in the acidic solution to the chelating resin; eluting the scandium adsorbed to the chelating resin to obtain a scandium eluate ; and the chelating resin. An ion exchange treatment step having a step of removing chromium adsorbed on
In the step of adsorbing the scandium to the chelate resin in the ion exchange treatment step, the temperature of the acidic solution is maintained in the range of more than 20° C. and 50° C. or less when bringing the acidic solution into contact with the chelate resin. make contact,
In the step of removing chromium adsorbed on the chelate resin in the ion exchange treatment step, a sulfuric acid solution having a concentration of 3N or more and an amount equal to or more than the volume of the chelate resin (1 time) is used.
Scandium recovery method. The acidic solution is a solution after subjecting nickel oxide ore to leaching treatment with sulfuric acid and adding a sulfiding agent to the obtained leachate to separate nickel sulfide.
The method for recovering scandium according to claim 1. wherein the chelate resin is a resin having iminodiacetic acid as a functional group;
The method for recovering scandium according to claim 1 or 2. The ion exchange treatment step includes
contacting the chelating resin that has adsorbed scandium with less than 0.3N sulfuric acid to remove aluminum that has adsorbed to the chelating resin;
In the step of eluting the scandium adsorbed on the chelate resin to obtain a scandium eluate, the chelate resin from which aluminum has been removed is brought into contact with sulfuric acid of 0.3 N or more and less than 3 N, and the scandium adsorbed on the chelate resin is eluted to obtain a scandium eluate. obtaining an eluent,
Repeatedly using the chelate resin after removing the chromium in the step of adsorbing the scandium,
The method for recovering scandium according to any one of claims 1 to 3. An ion exchange treatment method for obtaining a scandium-enriched solution by subjecting an acidic solution containing at least scandium and chromium to an ion exchange treatment using a chelate resin,
contacting the acidic solution with the chelating resin to adsorb scandium in the acidic solution to the chelating resin; eluting the scandium adsorbed to the chelating resin to obtain a scandium eluate; removing adsorbed chromium ;
In the step of adsorbing scandium to the chelate resin, when the acidic solution is brought into contact with the chelate resin, the temperature of the acidic solution is maintained in the range of more than 20 ° C. and 50 ° C. or less .
In the step of removing chromium adsorbed on the chelate resin in the ion exchange treatment step, a sulfuric acid solution having a concentration of 3N or more and an amount equal to or more than the volume of the chelate resin (1 time) is used.
Ion exchange treatment method.

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