JP2017137553A - Method for collecting scandium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and efficiently collect scandium of high purity from nickel oxide ore.SOLUTION: There is provided a method for collecting scandium which includes: an adsorption step S21 of passing a scandium-containing solution through an ion exchange resin to adsorb scandium on the ion exchange resin; an elution step S23 of eluting the scandium from the ion exchange resin to obtain a post-elution liquid; a scandium extraction step S3 of subjecting a solution containing the scandium to solvent extraction using a scandium extraction agent containing an amide derivative to obtain an organic phase containing the scandium, after the elution step S23; and preferably, further includes a precipitation step S42 of adding an oxalic acid to a back extraction liquid of the organic phase containing the scandium to precipitate scandium oxalate, and an oxidation step S43 of oxidizing the scandium oxalate to obtain scandium oxide, where a pH of the solution when the oxalic acid is added to the solution containing the scandium is 0 or more and 1.0 or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a scandium recovery method, and more particularly to a method for recovering scandium contained in nickel oxide ore simply and efficiently using solvent extraction with a scandium extractant containing a specific amide derivative.

  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, HPAL (High Pressure Acid Leach) in which nickel oxide ore is charged into a pressure vessel together with sulfuric acid and heated to a high temperature of about 240 ° C. to 260 ° C. and separated into a leaching solution containing nickel and a leaching residue. ) The process is in practical use. In this HPAL process, impurities are separated by adding a neutralizing agent to the obtained leachate, and then nickel is recovered as nickel sulfide by adding a sulfiding agent to the leachate from which impurities have been separated. And by processing this nickel sulfide by the existing nickel smelting process, electric nickel and a nickel salt compound can be obtained.

  When the HPAL process as described above is used, scandium contained in the nickel oxide ore is contained in the leachate together with nickel (see Patent Document 1). And when neutralizing agent is added to the leachate obtained by the HPAL process to separate impurities, and then sulfurizing agent is added, nickel is recovered as nickel sulfide, while scandium is added after the sulfurizing agent is added. Because it becomes contained in the acidic solution, nickel and scandium can be effectively separated by using the HPAL process.

  There is also a method in which scandium is separated using a chelate resin (see Patent Document 2). Specifically, in the method disclosed in Patent Document 2, first, nickel and scandium are selectively leached into an acidic aqueous solution under high temperature and high pressure in an oxidizing atmosphere from a nickel-containing oxide ore to obtain an acidic solution. Then, after adjusting the pH of the acidic solution to a range of 2 to 4, nickel is selectively collected as a sulfide by using a sulfurizing agent. Next, the obtained nickel-recovered solution is brought into contact with a chelate resin to adsorb scandium, the chelate resin is washed with dilute acid, and then the washed chelate resin is brought into contact with a strong acid to elute scandium from the chelate resin. It is to do.

As a method for recovering scandium from the above acidic solution, a method of recovering scandium using solvent extraction has also been proposed (see Patent Documents 3 and 4). Specifically, in the method described in Patent Document 3, first, in addition to scandium, an aqueous phase scandium-containing solution containing at least one of iron, aluminum, calcium, yttrium, manganese, chromium, and magnesium is used. An organic solvent obtained by diluting 2-ethylhexylsulfonic acid-mono-2-ethylhexyl with kerosene is added, and the scandium component is extracted into the organic solvent. Next, in order to separate yttrium, iron, manganese, chromium, magnesium, aluminum and calcium extracted together with scandium in an organic solvent, they are removed by adding scrubbing with an aqueous hydrochloric acid solution, and then in the organic solvent. by adding NaOH solution, scandium remaining in the organic solvent to prepare a slurry containing Sc (OH) _3, which by the Sc (OH) ₃ obtained by filtration was dissolved in hydrochloric acid, to obtain the chloride scandium solution. Then, oxalic acid is added to the obtained scandium chloride aqueous solution to form a scandium oxalate precipitate. The precipitate is filtered to separate iron, manganese, chromium, magnesium, aluminum, and calcium into the filtrate, followed by calcination. Thus, high-purity scandium oxide is obtained.

  Patent Document 4 describes a method of selectively separating and recovering scandium from a scandium-containing supply liquid by bringing the scandium-containing supply liquid into contact with an extractant at a constant rate by batch processing.

  As for the quality of scandium recovered by these methods, it is known that a purity of about 95% to 98% can be obtained in terms of scandium oxide. However, although it is of a sufficient quality for applications such as addition to alloys, it has a higher purity for applications such as fuel cell electrolytes, for which demand has been increasing in recent years. For example, a grade of about 99.9% is required.

JP-A-3-173725 JP-A-9-194211 Japanese Patent Laid-Open No. 9-291320 International Publication No. 2014/110216

  However, the nickel oxide ore described above contains various other impurity elements such as manganese and magnesium in addition to iron and aluminum. In this case, in the chelate resins and organic solvents disclosed in Patent Document 2 and Patent Document 3, some impurity elements exhibit similar behavior to scandium, and it is difficult to effectively separate and recover from scandium. In addition, impurities such as iron and aluminum contained in the leachate of nickel oxide ore are much higher in concentration than scandium, and due to these large amounts of impurities, high purity scandium is produced from nickel oxide ore. No suitable method has been found for recovery.

  The present invention has been proposed in view of the above-described circumstances, and an object of the present invention is to provide a scandium recovery method capable of easily and efficiently recovering high-purity scandium from nickel oxide ore.

  The inventors of the present invention have made extensive studies in order to solve the above-described problems. As a result, it is possible to easily and efficiently recover high-purity scandium from nickel oxide ore by subjecting an acidic solution containing scandium to solvent extraction of scandium using a scandium extractant containing a specific amide derivative. As a result, the present invention has been completed. That is, the present invention provides the following.

  (1) In the first invention of the present invention, an adsorption process in which a solution containing scandium is passed through an ion exchange resin and the scandium is adsorbed on the ion exchange resin, and a sulfuric acid solution is passed through the ion exchange resin. Elution step of eluting the scandium from the ion exchange resin to obtain a solution after elution, and after the elution step, the solution containing the scandium is subjected to solvent extraction using a scandium extractant containing an amide derivative. And a scandium extraction method that includes a scandium extraction step of separating into an aqueous phase containing impurities and an organic phase containing scandium.

  (2) In addition, the second invention of the present invention further includes a concentration step of concentrating the post-elution liquid after the elution step in the first invention, wherein the impurity extraction step is a step of the concentration step. This is a scandium recovery method to be performed later.

  (3) Further, in the third invention of the present invention, in the first or second invention, the post-elution solution contains trivalent iron as an impurity, and after the elution step, water containing the scandium is contained. The method further includes a reduction step of reducing the trivalent iron contained in the phase to divalent iron, and the scandium extraction step is a scandium recovery method performed after the reduction step.

  (4) Further, in the fourth invention of the present invention, in any one of the first to third inventions described above, the scandium back extraction is obtained by subjecting the organic phase containing scandium to back extraction to obtain a scandium back extract. And a step of adding oxalic acid to the scandium-containing solution after the scandium back extraction step to precipitate scandium oxalate; and an oxidation step of oxidizing the scandium oxalate to obtain scandium oxide. And a scandium recovery method in which the pH of the solution is 0 or more and 1.0 or less when oxalic acid is added to the solution containing scandium.

（式（Ｉ）において、Ｒ^１及びＲ^２は、それぞれ同一又は別異のアルキル基を示す。アルキル基は直鎖でも分鎖でも良い。Ｒ^３は水素原子又はアルキル基を示す。Ｒ^４は水素原子、又はアミノ酸としてα炭素に結合される、アミノ基以外の任意の基を示す。） (5) The fifth invention of the present invention is the scandium recovery method according to any one of the first to fourth inventions, wherein the amide derivative is represented by the following general formula (I).

(In Formula (I), R ¹ and R ² each represent the same or different alkyl group. The alkyl group may be linear or branched. R ³ represents a hydrogen atom or an alkyl group. R ⁴ represents A hydrogen atom or an arbitrary group other than an amino group bonded to the α-carbon as an amino acid is shown.)

  (6) Further, in a sixth invention of the present invention according to any one of the first to fifth inventions, the solution that is passed through the ion exchange resin in the adsorption step is nickel oxide ore under high temperature and high pressure. This is a scandium recovery method, which is an acid solution leached with sulfuric acid.

  According to the present invention, high-purity scandium can be easily and efficiently recovered from nickel oxide ore.

It is a flowchart for demonstrating the scandium collection | recovery method which concerns on embodiment of this invention. It is a graph which shows the relationship between pH and an extraction rate when the acidic solution containing scandium, divalent iron, and trivalent iron is attached | subjected to the solvent extraction process by the organic solvent containing amide derivative D2EHAG. It is a graph which shows the relationship between the pH of the extraction start liquid in the scandium extraction process S33 using the organic solvent containing amide derivative D2EHAG, and the extraction rate of Sc, Fe (II), and Al. It is a graph which shows the relationship between the density | concentration of the back extraction liquid (sulfuric acid) in scandium back extraction process S34, and the ratio of the scandium contained in the liquid after back extraction.

  Hereinafter, specific embodiments of the method for recovering scandium according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and the gist of the present invention is changed. In the range which does not carry out, it can change and implement suitably.

<< 1. Scandium recovery method >>
FIG. 1 is a flowchart showing an example of a scandium recovery method according to this embodiment. In this scandium recovery method, scandium and impurities are separated from an acidic solution containing scandium and impurities, which is obtained by leaching nickel oxide ore with an acid such as sulfuric acid. It is efficiently recovered.

  In this scandium recovery method, scandium is extracted into a scandium extractant (organic phase) by subjecting an acidic solution (processed solution) containing scandium and impurities to solvent extraction using a scandium extractant containing an amide derivative. And separated from impurities remaining in the acidic solution (aqueous phase). Scandium extracted by the scandium extractant (organic phase) is subjected to back extraction, separated into an acidic solution (aqueous phase) containing scandium and an organic phase, oxalic acid is added to the aqueous phase, and scandium oxalate is added. It is recovered by precipitating.

  As described above, the scandium recovery method according to the present embodiment is characterized in that when separating and recovering scandium by solvent extraction, it is subjected to solvent extraction using a scandium extractant containing an amide derivative. According to such a method, impurities can be separated more effectively, stable operation can be performed even from a raw material containing many impurities such as nickel oxide ore, and high purity. Can be efficiently recovered.

  For example, as shown in the flow diagram of FIG. 1, the scandium recovery method according to this embodiment is a nickel oxide ore that obtains an acidic solution containing scandium and impurities by leaching the nickel oxide ore with an acid such as sulfuric acid. A hydrometallurgy treatment step S1, a scandium elution step S2 for obtaining a scandium eluate in which scandium is concentrated by removing impurities from the acidic solution, and the scandium eluent is a solvent using a scandium extractant containing an amide derivative. Scandium is extracted into scandium extractant (organic phase), and scandium extraction step S3 in which it separates from other impurities remaining in the acidic solution (aqueous phase), and scandium extractant (organic phase) is subjected to back extraction. And a scandium recovery step S4 for recovering scandium from the back extract (aqueous phase) containing scandium. .

≪2. About each step of the scandium recovery method >>
<2-1. Nickel oxide ore hydrometallurgical treatment process>
An acidic solution obtained by treating nickel oxide ore with sulfuric acid can be used as the acidic solution containing scandium to be processed for scandium recovery.

  Specifically, as an acidic solution subjected to solvent extraction, a leaching step S11 in which nickel oxide ore is leached with an acid such as sulfuric acid at high temperature and high pressure to obtain a leachate, and a neutralizer is added to the leachate to remove impurities. A nickel oxide ore having a neutralization step S12 for obtaining a neutralized starch and a post-neutralization solution, and a sulfurization step S13 for obtaining a nickel sulfide and a post-sulfurization solution by adding a sulfiding agent to the post-neutralization solution The post-sulfurization solution obtained by the hydrometallurgical treatment step S1 can be used. Below, the flow of the hydrometallurgical treatment process S1 of nickel oxide ore will be described.

[Leaching step S11]
The leaching step S11 is composed of a leachate and a leaching residue by adding sulfuric acid to a slurry of nickel oxide ore and stirring at a temperature of 240 ° C. to 260 ° C. using, for example, a high-temperature pressurized container (autoclave). It is a process of forming a leaching slurry. In addition, what is necessary is just to perform the process in leaching process S11 according to the conventionally known HPAL process, for example, it describes in patent document 1. FIG.

  Here, examples of the nickel oxide ore include so-called laterite ores such as limonite ore and saprolite ore. Laterite ore usually has a nickel content of 0.8 to 2.5% by weight, and is contained as a hydroxide or siliceous clay (magnesium silicate) mineral. These nickel oxide ores contain scandium.

  In the leaching step S11, the leaching slurry composed of the obtained leaching liquid and leaching residue is washed, and solid-liquid separation is performed into the leaching liquid containing nickel, cobalt, scandium, and the like, and the leaching residue that is hematite. In this solid-liquid separation process, for example, after the leaching slurry is mixed with a cleaning liquid, the solid-liquid separation process is performed by a solid-liquid separation facility such as a thickener using a flocculant supplied from a flocculant supply facility or the like. Specifically, the leaching slurry is first diluted with a cleaning liquid, and then the leaching residue in the slurry is concentrated as a thickener sediment. In this solid-liquid separation treatment, it is preferable to use solid-liquid separation tanks such as thickeners connected in multiple stages and perform solid-liquid separation while washing the leaching slurry in multiple stages.

[Neutralization step S12]
The neutralization step S12 is a step of adding a neutralizing agent to the leachate obtained in the above-described leaching step S11 to adjust pH to obtain a neutralized starch containing an impurity element and a post-neutralization solution. By the neutralization treatment in this neutralization step S12, valuable metals such as nickel, cobalt, and scandium are included in the post-neutralization solution, and most of impurities such as iron and aluminum become neutralized starch. .

  A conventionally well-known thing can be used as a neutralizer, For example, a calcium carbonate, slaked lime, sodium hydroxide etc. are mentioned.

  In the neutralization treatment in the neutralization step S12, it is preferable to adjust the pH to a range of 1 to 4 while suppressing the oxidation of the separated leachate, and adjust the pH to a range of 1.5 to 2.5. More preferably. If the pH is less than 1, neutralization becomes insufficient, and there is a possibility that the neutralized starch and the liquid after neutralization cannot be separated. On the other hand, when the pH exceeds 4, not only impurities such as aluminum but also valuable metals such as scandium and nickel may be contained in the neutralized starch.

[Sulfurization step S13]
The sulfidation step S13 is a step of obtaining a nickel sulfide and a post-sulfurization solution by adding a sulfiding agent to the post-neutralization solution obtained by the neutralization step S12 described above. By the sulfiding treatment in the sulfiding step S13, nickel, cobalt, zinc and the like become sulfides, and scandium and the like are included in the solution after sulfiding.

  Specifically, in the sulfiding step S13, a sulfurizing agent such as hydrogen sulfide gas, sodium sulfide, sodium hydrogen sulfide is blown into the obtained post-neutralized liquid, and sulfide containing nickel and cobalt having a small amount of impurity components. Product (nickel / cobalt mixed sulfide) and the nickel concentration are stabilized at a low level, and a post-sulfurization solution containing scandium or the like is produced.

  In the sulfiding treatment in the sulfiding step S13, the nickel / cobalt mixed sulfide slurry is subjected to settling separation using a settling separator such as a thickener, and the nickel / cobalt mixed sulfide is separated and recovered from the bottom of the thickener. On the other hand, the post-sulfurization solution that is an aqueous solution component is recovered by overflowing.

  In the scandium recovery method according to the present embodiment, the post-sulfurization solution obtained through each step in the above-described nickel oxide ore hydrometallurgical treatment step S1 is an acid containing scandium that is the target of the scandium recovery process. It can be used as a solution.

<2-2. Scandium (Sc) elution step>
As described above, a post-sulfurization solution that is an acidic solution containing scandium obtained by leaching nickel oxide ore with sulfuric acid can be applied as a target solution for scandium recovery treatment. However, the post-sulfurization solution that is an acidic solution containing scandium contains, in addition to scandium, for example, aluminum, chromium, and other impurities that remain in the solution without being sulfided by the sulfidation treatment in the above-described sulfidation step S13. ing. Therefore, when subjecting this acidic solution to solvent extraction, as a scandium elution step S2, impurities contained in the acidic solution are removed in advance to concentrate scandium (Sc), and a scandium eluent (scandium-containing solution) is used. Preferably, it is generated.

  In the scandium elution step S2, for example, an ion exchange treatment method can be used to separate and remove impurities such as aluminum contained in the acidic solution to obtain a scandium-containing solution in which scandium is concentrated.

  In the following, referring to the flow chart of FIG. 1, as an example of a method of removing impurities contained in an acidic solution and concentrating and eluting scandium, a method of performing an ion exchange reaction using a chelate resin is given as an example. However, the present invention is not limited to this method.

  The mode of the ion exchange reaction is not particularly limited. For example, the adsorption step S21 in which the post-sulfurization solution is brought into contact with the chelate resin to adsorb scandium to the chelate resin, and the chelate resin having adsorbed scandium is 0.1N. An aluminum removal step S22 for removing aluminum adsorbed on the chelate resin by contacting with the following sulfuric acid, and a scandium elution step S23 for obtaining a scandium eluent by contacting the chelate resin with 0.3 to 3N sulfuric acid. Can be illustrated. Further, although not essential, in order to make the chelate resin reusable, 3N or more sulfuric acid is brought into contact with the chelate resin that has undergone the scandium elution step S23, and the chromium removal that removes the chromium adsorbed on the chelate resin in the adsorption step S21 It is preferable to further include step S24. Hereinafter, the outline of each process will be briefly described.

[Adsorption process S21]
In the adsorption step S21, the sulfurized solution is brought into contact with the chelate resin to adsorb scandium to the chelate resin. The type of chelate resin is not particularly limited, and for example, a resin having iminodiacetic acid as a functional group can be used.

[Aluminum removal step S22]
Although not essential, prior to elution of scandium from the chelate resin adsorbing scandium in the adsorption step S21, 0.1 N or less sulfuric acid was brought into contact with the chelate resin adsorbed scandium in the adsorption step S21 and adsorbed on the chelate resin. It is preferable to perform an aluminum removal step S22 for removing aluminum. By performing aluminum removal process S22, aluminum can be removed from chelate resin, making scandium adsorb | suck to chelate resin.

  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.

[Scandium elution step S23]
In the scandium elution step S23, 0.3 to 3N sulfuric acid is brought into contact with the chelate resin adsorbed with scandium to obtain a scandium eluent. When obtaining a scandium eluent, the normality of sulfuric acid used in the eluent is preferably maintained in the range of 0.3N to 3N, and more preferably in the range of 0.5N to 2N.

[Chromium removal step S24]
Although not essential, in order to be able to reuse the chelate resin, a chromium removal step S24 in which 3N or more sulfuric acid is brought into contact with the chelate resin that has undergone the scandium elution step S23, and the chromium adsorbed on the chelate resin in the adsorption step S21 is removed. It is preferable to carry out. In the chromium removal step S24, 3N or more sulfuric acid is brought into contact with the chelate resin that has undergone the scandium elution step S23, and the chromium adsorbed on the chelate resin in the adsorption step S21 is removed. When removing the chromium, if the normality of the sulfuric acid used for the eluent is less than 3N, the chromium is not properly removed from the chelate resin, which may cause a problem when the chelate resin is reused.

<2-3. Scandium extraction process>
Next, in the scandium extraction step S3, the scandium eluate obtained in the scandium elution step S23 is subjected to solvent extraction with a scandium extractant containing an amide derivative, so that impurities in the extraction residual liquid are extracted (water In the phase), the scandium is distributed to the extractant (organic phase) to separate scandium and impurities, and the scandium-containing extract (organic phase) and sulfuric acid are contacted to contain scandium. A back extract (aqueous phase) is obtained.

  The embodiment in the scandium extraction step S3 is not particularly limited, but a scandium-containing solution and an extractant that is an organic solvent are mixed to extract a slight impurity and an extracted organic solvent (organic phase) from which scandium is extracted, leaving the impurity. Scandium extraction step S33 that separates into the extracted residual liquid (aqueous phase), and a sulfuric acid solution is mixed with the organic solvent after extraction, and the scandium extracted into the organic solvent after extraction is separated into the aqueous phase to obtain a back extract. It is preferable to have a back extraction step S34.

[Concentration step S31]
Although not essential, when the scandium concentration in the eluent is extremely low, the scandium may be concentrated by neutralization with sodium hydroxide or dissolution with sulfuric acid. By passing through the concentration step S31, the volume of scandium-containing solution can be reduced, and as a result, the amount of scandium extractant used can be suppressed.

[Reduction Step S32]
Although not essential, it is preferable to perform a reduction treatment S32 for reducing trivalent iron contained as an impurity in the scandium eluent to divalent iron before mixing the scandium-containing solution and the organic solvent containing the extractant. By performing this reduction treatment S32, in the subsequent scandium extraction step S33, the selectivity to iron extraction residue (aqueous phase) as an impurity increases, and as a result, the quality (purity) of the recovered scandium is increased. be able to.

  The aspect of reduction process S32 is not specifically limited. For example, blowing hydrogen sulfide gas into the scandium eluent can be mentioned.

[Scandium Extraction Step S33]
In the scandium extraction step S33, a scandium-containing solution and an organic solvent containing an extractant are mixed, scandium is selectively extracted into the organic solvent, and contains an organic solvent (organic phase) containing scandium and impurities. A residual extraction liquid (aqueous phase) is obtained. The scandium recovery method according to the present embodiment is characterized in that in this scandium extraction step S33, solvent extraction is performed using a scandium extractant containing an amide derivative. By performing a solvent extraction process using a scandium extractant containing an amide derivative, various metals (aluminum, iron, etc.) contained in the scandium-containing solution can be separated as impurities.

(Amide derivative)
The amide derivative constituting the scandium extractant has a feature of high selectivity with scandium. Examples of such amide derivatives include those represented by the following general formula (I). By introducing an alkyl group into the amide skeleton, the lipophilicity can be increased and used as an extractant.

In the formula, the substituents R ¹ and R ² each represent the same or different alkyl group. The alkyl group may be linear or branched, but the alkyl group is preferably branched because solubility in an organic solvent can be improved. By introducing an alkyl group into the amide skeleton, the lipophilicity can be increased and used as an extractant.

In R ¹ and R ² , the carbon number of the alkyl group is not particularly limited, but is preferably 5 or more and 11 or less. When the number of carbon atoms is 4 or less, the water solubility of the amide derivative increases, and the amide derivative may be contained in the aqueous phase. When the number of carbon atoms is 12 or more, the surface activity is increased and an emulsion is easily formed. In addition, when the carbon number is 12 or more, the third amide derivative layer can be formed separately from the aqueous phase containing the acidic solution and the organic phase containing the organic solvent.

R ³ represents a hydrogen atom or an alkyl group. R ⁴ represents a hydrogen atom or an arbitrary group other than an amino group bonded to the α-carbon as an amino acid.

  The amide derivative is not particularly limited as long as it can selectively extract scandium, but is preferably a glycinamide derivative in that it can be easily produced. When the amide derivative is a glycinamide derivative, the above glycinamide derivative can be synthesized by the following method.

First, 2-halogenated acetyl halide is added to an alkylamine having a structure represented by NHR ¹ R ² (R ¹ and R ² are the same as the above substituents R ¹ and R ² ), and an amine is obtained by nucleophilic substitution reaction. Is substituted with 2-halogenated acetyl to give 2-halogenated (N, N-di) alkylacetamide.

  Next, the above-mentioned 2-halogenated (N, N-di) alkylacetamide is added to glycine or an N-alkylglycine derivative, and one of the hydrogen atoms of the glycine or N-alkylglycine derivative is (N, N) by a nucleophilic substitution reaction. Substitution with an N-di) alkylacetamide group. A glycine alkylamide derivative can be synthesized by these two-step reactions.

  In addition, histidine amide derivatives, lysine amide derivatives, and aspartic acid amide derivatives can be synthesized by replacing glycine with histidine, lysine, and aspartic acid. The extraction behavior with glycine alkylamide derivatives, histidine amide derivatives, lysine amide derivatives, and aspartic acid amide derivatives is considered to fall within the range of results using glycine derivatives from the complex stability constants of manganese, cobalt, and the like.

When the compound represented by the general formula (I) is a histidine amide derivative, the histidine amide derivative is represented by the following general formula (II).

When the compound represented by the general formula (I) is a lysine amide derivative, the lysine amide derivative is represented by the following general formula (III).

When the compound represented by the general formula (I) is an aspartic acid amide derivative, the aspartic acid amide derivative is represented by the following general formula (IV).

In the formulas (II) to (IV), the substituents R ¹ and R ² are the same as those described in the formula (I).

  The amide derivative may be a normal-methylglycine derivative.

(Extraction of scandium)
In order to extract scandium ions using the amide derivative, this acidic aqueous solution is added to and mixed with the organic solution containing the amide derivative while adjusting the acidic aqueous solution containing the target scandium ion. Thereby, the target scandium ion can be selectively extracted into the organic phase.

  At the time of extraction, it is preferable to use a scandium extractant containing an amide derivative diluted with, for example, a hydrocarbon-based organic solvent. The organic solvent may be any solvent as long as the amide derivative and the metal extraction species are dissolved, for example, a chlorinated solvent such as chloroform and dichloromethane, and an aromatic hydrocarbon such as benzene, toluene and xylene. And aliphatic hydrocarbons such as hexane. These organic solvents may be used alone or in combination, and alcohols such as 1-octanol may be mixed.

  The concentration of the amide derivative can be appropriately set depending on the concentration of scandium, but considering phase separation during extraction and back-extraction described later, the concentration is about 10% by volume to 30% by volume with respect to 100% by volume of the organic solvent. It is preferable that there is about 20 volume% especially.

  In order to efficiently recover scandium from an acidic aqueous solution containing scandium and impurities (mainly divalent iron and aluminum), the organic extractant is adjusted while adjusting the pH of the acidic aqueous solution containing scandium to 2.5 or lower. It is preferable to add a solution, and it is more preferable to add an organic solution of the extractant while adjusting the pH to 1.5 or lower. If the pH is too high, not only scandium but also impurities may be extracted into the organic phase.

  The lower limit of the pH is not particularly limited, but it is more preferable to add the organic solution of the extractant while adjusting the pH to 1 or more. If the pH is too low, scandium cannot be sufficiently extracted, and scandium may remain in the aqueous phase.

  What is necessary is just to set stirring time and extraction temperature suitably with the conditions of the acidic aqueous solution of a scandium ion, and the organic solution of an extracting agent.

[Scandium Back Extraction Step S34]
In the scandium back extraction step S34, scandium is back extracted from the organic solvent from which scandium was extracted in the scandium extraction step S33. Specifically, in the scandium back extraction step S34, a reaction reverse to the extraction process in the scandium extraction step S33 occurs by adding and mixing a back extraction solution (back extraction start solution) to an organic solvent containing an amide derivative. Thus, scandium is back-extracted to obtain a back-extracted liquid (aqueous phase) containing scandium.

  As a solution used for back extraction, a sulfuric acid solution, water, or the like can be used. Moreover, what added the soluble sulfate to water can also be used. Specifically, when a sulfuric acid solution is used as the back extraction solution, it is preferable to use a solution having a concentration range of 1.0 mol / L to 2.0 mol / L.

  The number of reverse extraction steps (number of times) depends on the type and concentration of the impurity element, and can be appropriately changed depending on the scandium extractant made of the amide derivative used, the extraction conditions, and the like. For example, when the phase ratio O / A = 1 of the organic phase (O) and the aqueous phase (A) is set to 1, the number of reverse extraction stages is about 3 to 5, so that scandium extracted in the organic solvent can be analyzed. Can be recovered to below the lower detection limit.

  The extraction agent (organic phase) after adding the sulfuric acid solution to the extraction agent after the extraction and recovering scandium is repeatedly used as the extraction agent in the scandium extraction step S33. can do.

<2-4. Scandium recovery process>
Next, in the scandium recovery step S4, scandium is recovered from the back extract obtained in the scandium extraction step S3.

  The scandium recovery method in the scandium recovery step S4 is not particularly limited, and a known method can be used. Known methods include adding alkali to the post-extraction solution (aqueous phase) to neutralize and recover it as scandium hydroxide starch, or adding oxalic acid to the post-extraction solution (aqueous phase) and oxalic acid. Examples thereof include a method of recovering as a scandium starch. Among these, it is preferable to add oxalic acid to the post-extraction solution (aqueous phase) in that impurities can be more effectively separated.

  In the method of adding oxalic acid to the liquid after back extraction (aqueous phase), first, if necessary, scandium contained in the liquid after back extraction (aqueous phase) is concentrated. Subsequently, oxalic acid is added to the aqueous phase to form a scandium oxalate precipitate, and then the scandium oxalate is dried and roasted to be recovered as scandium oxide.

[Concentration step S41]
When the scandium concentration in the back extract obtained in the scandium extraction step S3 is low, the post-extract solution (aqueous phase) can be neutralized with sodium hydroxide and dissolved with sulfuric acid to concentrate scandium. preferable.

  In addition to sodium hydroxide, calcium carbonate and slaked lime are also known as neutralizing agents. However, the liquid after back extraction (aqueous phase) is a sulfuric acid solution, and if the neutralizing agent contains Ca, gypsum is generated by the addition of the neutralizing agent, which is not preferable.

  The pH when the neutralizing agent is added is preferably 6.0 or more. If the pH is too low, neutralization is insufficient and Sc may not be sufficiently recovered.

  The upper limit of the pH when the neutralizing agent is added is not particularly limited, but from the viewpoint of suppressing the use amount of the neutralizing agent, the pH when the neutralizing agent is added is preferably 7.0 or less. .

[Scandium Oxalate Precipitation Step S42]
In the scandium oxalate precipitation step S42, a predetermined amount of oxalic acid is added to the liquid after back extraction (aqueous phase) or the concentrate after the concentration step S41, and precipitated and precipitated as a scandium oxalate solid to separate from the liquid phase. It is a process to do.

  The pH when oxalic acid is added is preferably 0 or more and 1.0 or less, more preferably 0.5 or more and 1.0 or less, and further preferably 0.7 or more and 1.0 or less. preferable. If the pH is too low, the solubility of scandium oxalate will increase, and the scandium recovery rate can be reduced. If the pH is too high, not only scandium oxalate but also the oxalate of impurities contained in the solution after back extraction (aqueous phase) or the concentrate after the concentration step S41 may precipitate, and the scandium purity of the precipitate may decrease.

  When the scandium recovery step S4 is directly performed on the scandium eluent obtained through the hydrometallurgical treatment step S1 and the scandium elution step S2 without performing the scandium extraction step S3, the pH when oxalic acid is added is 0. Otherwise, the oxalate salt of impurities contained in the scandium eluent may also precipitate, and the scandium purity of the precipitate may decrease. Therefore, in order to obtain high-quality scandium, the pH must be in the vicinity of 0 even if the yield is sacrificed.

  In the invention described in the present embodiment, since the original solution used in the scandium oxalate precipitation step S42 is purified, high-quality scandium can be recovered even if the pH when oxalic acid is added is close to 1. Therefore, the invention described in the present embodiment has a remarkable effect that both quality and yield can be achieved.

  The amount of oxalic acid added is not particularly limited, but may be 1.05 times or more and 3.0 times or less the equivalent amount required for precipitating scandium contained in the extracted residue as oxalate. Preferably, the amount is 1.5 times or more and 2.5 times or less, more preferably 1.7 times or more and 2.3 times or less. If the amount added is too small, there is a possibility that the entire amount of scandium cannot be recovered. On the other hand, if the amount added is too large, the solubility of the resulting scandium oxalate increases, so that scandium is redissolved and the recovery rate decreases, or excessive sodium chlorite is decomposed to decompose excess oxalic acid. The amount of the oxidizing agent used increases.

[Roasting step S43]
The roasting step S43 is a step in which the precipitate of scandium oxalate obtained in the scandium oxalate precipitation step S43 is washed with water and dried, and then roasted. By undergoing the roasting process in the roasting step S43, scandium can be recovered as extremely high-purity scandium oxide.

  The conditions for the roasting treatment 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. Industrially, it is preferable to use a continuous furnace such as a rotary kiln because drying and roasting can be performed in the same apparatus.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all.

<Test Example 1> Construction of scandium recovery process [Example 1]
[Wet smelting treatment step S1]
(Leaching step S11)
First, nickel oxide ore was subjected to pressure acid leaching using sulfuric acid based on a known method such as the method described in Patent Document 1.

(Neutralization step S12)
Subsequently, the pH of the obtained leachate was adjusted to remove impurities.

(Sulfurization step S13)
Thereafter, a sulfiding agent was added to the leachate after removing the impurities to remove the solid nickel sulfide to prepare a post-sulfurization solution. This solution after sulfiding is used as a scandium-containing solution (original solution before extraction). Table 1 shows the composition of the post-sulfurization solution.

  It should be noted that an aqueous sodium hydroxide solution is added to the post-sulfurization solution obtained through the hydrometallurgical treatment step S1 until the pH becomes 6.8 to generate a hydroxide starch, and the scandium contained in the hydroxide starch is produced. When the quality (purity) was measured, the quality (purity) of scandium was only about 0.1% by weight.

[Scandium elution step S2]
(Adsorption process S21)
Next, the obtained post-sulfurized solution was brought into contact with the chelate resin to adsorb scandium to the chelate resin. In this example, a resin having iminodiacetic acid as a functional group was used as the chelate resin.

(Aluminum removal step S22)
Next, 0.05 N sulfuric acid was brought into contact with the chelate resin on which scandium was adsorbed to remove aluminum adsorbed on the chelate resin.

(Scandium elution step S23)
Next, 0.5N sulfuric acid was brought into contact with the chelate resin on which scandium was adsorbed to obtain a scandium eluent.

  In addition, an aqueous solution of sodium hydroxide is added to the scandium eluent obtained through the hydrometallurgical treatment step S1 and the scandium elution step S2 until the pH becomes 6.8 to generate a hydroxide starch, As a result of measuring the quality (purity) of scandium contained in the product, the quality (purity) of scandium was about 50% by weight. This grade is inappropriate when it is desired to provide high-purity scandium.

[Scandium extraction step S3]
(Concentration step S31)
Subsequently, the scandium eluent was concentrated by a known method such as heating to obtain a pre-extraction original solution. Table 2 shows the composition of the original solution before extraction.

(Reduction process S32)
Hydrogen sulfide gas was blown into the original solution before extraction to reduce the valence of iron ions contained as impurities from 3 to 2.

(Scandium extraction step S33)
(1) Synthesis of Amide Derivative D2EHAG As an example of an amide derivative, a glycinamide derivative represented by the above general formula (I), that is, N- [N, N-bis (2- Ethylhexyl) aminocarbonylmethyl] glycine (N- [N, N-Bis (2-ethylhexyl) aminocarbonylmethyl] glycine) (or N, N-di (2-ethylhexyl) acetamido-2-glycine (N, N-di (2 -Ethylhexyl) acetamide-2-glycine), hereinafter referred to as "D2EHAG").

D2EHAG was synthesized as follows. First, as shown in the following reaction formula (V), 23.1 g (0.1 mol) of commercially available di (2-ethylhexyl) amine and 10.1 g (0.1 mol) of triethylamine were fractionated and mixed with chloroform. Then, 13.5 g (0.12 mol) of 2-chloroacetyl chloride was added dropwise, then washed once with 1 mol / l hydrochloric acid, then with ion-exchanged water, and the chloroform phase was separated. did.
Next, an appropriate amount (about 10 to 20 g) of anhydrous sodium sulfate was added and dehydrated, followed by filtration to obtain 29.1 g of a yellow liquid. When the structure of this yellow liquid (reaction product) was identified using a nuclear magnetic resonance analyzer (NMR), the yellow liquid was identified as 2-chloro-N, N-di (2-ethylhexyl) acetamide (hereinafter “ CDEHAA ”)). The yield of CDEHAA was 90% with respect to di (2-ethylhexyl) amine as a raw material.

  Next, as shown in the following reaction formula (VI), methanol was added to and dissolved in 8.0 g (0.2 mol) of sodium hydroxide, and the solution in which 15.01 g (0.2 mol) of glycine was further added was stirred. Then, 12.72 g (0.04 mol) of the above CDEHAA was slowly added dropwise and stirred. After completion of the stirring, the solvent in the reaction solution was distilled off, and chloroform was added to the residue to dissolve it. The solution was acidified by adding 1 mol / l sulfuric acid, washed with ion-exchanged water, and the chloroform phase was separated.

An appropriate amount of anhydrous magnesium sulfate was added to the chloroform phase for dehydration and filtration. The solvent was removed again under reduced pressure to obtain 12.5 g of a yellow paste. The yield based on the above CDEHAA amount was 87%. When the structure of the yellow paste was identified by NMR and elemental analysis, it was confirmed that it had a D2EHAG structure as shown in FIGS. Through the above steps, an amide derivative D2EHAG as a scandium extractant was obtained.

(2) Solvent extraction of scandium contained in reducing solution 50 L of reducing solution after performing reduction step S32 is used as an extraction starting solution, and a solvent (Maruzen Oil Co., Ltd., Swazol 1800) is added to D2EHAG to add D2EHAG. 100 liters of an organic solvent whose concentration was adjusted to 20% by volume was mixed and stirred at room temperature for 60 minutes to carry out a solvent extraction treatment to obtain an organic solvent (organic phase) containing scandium.

The composition of each element contained in the extracted organic phase (organic phase) obtained by this extraction was analyzed. In Table 3, the percentage of the value obtained by dividing the amount of each element contained in the extracted organic phase by the amount of each element contained in the original solution before extraction is calculated, and the result is shown as the extraction rate (%). .

  As can be seen from the extraction rate results shown in Table 3, through the scandium extraction step S33, most of the scandium (Sc) contained in the original liquid before extraction (aqueous phase) is distributed to the organic solvent (organic phase), and Al Many impurities such as Fe and Fe could be separated.

[Back extraction step S34]
Subsequently, a sulfuric acid solution having a concentration of 1 mol / L is mixed with the extracted organic phase so as to have a phase ratio of O / A = 1/1, and the mixture is stirred for 60 minutes to perform the reverse extraction treatment S34, and scandium is added to water. Back extracted into phase (aqueous phase).

  The composition of various elements contained in the liquid after back extraction obtained by repeating this back extraction operation 3 times was analyzed. Table 4 calculates the percentage of the value obtained by dividing the amount of various elements contained in the solution after back extraction by the amount of various elements extracted in the organic phase in the scandium extraction step S33, and calculates the percentage of the back extraction (%) Shows the result.

  As can be seen from the recovery results shown in Table 4, by performing the solvent extraction process described above, almost 100% of the impurities contained in the original liquid before extraction was separated, and the organic after the scandium extraction step S33 was separated. Most of the scandium recovered from the phase could be recovered.

[Scandium recovery step S4]
[Concentration step S41]
Next, an aqueous sodium hydroxide solution is added to the obtained back extract until the pH reaches 6.8 to produce a hydroxide starch, which is thoroughly washed and then dissolved in sulfuric acid to start the next step. A liquid was obtained.

[Scandium Oxalate Precipitation Step S42]
Next, oxalic acid dihydrate (manufactured by Mitsubishi Gas Chemical Co., Inc.) in an amount that is twice the calculated amount of scandium contained in the starting solution is dissolved in the obtained starting solution. The mixture was stirred and mixed for 60 minutes to form a white crystalline precipitate of scandium oxalate. The pH of the solution at this time was 1.0.

[Roasting step S43]
Next, the obtained scandium oxalate precipitate was subjected to suction filtration, washed with pure water, and dried at 105 ° C. for 8 hours. Subsequently, the dried scandium oxalate was put in a tube furnace and maintained at 1100 ° C. and baked (fired) to obtain scandium oxide.

The composition of various elements contained in the starting liquid obtained in the concentration step S41 and the composition of various elements contained in scandium oxide obtained by roasting were analyzed by emission spectroscopic analysis. Table 5 shows the removal rate obtained by dividing the amounts of various components after roasting by the amounts of various components before the scandium oxalate precipitation step S42 (that is, included in the starting liquid obtained in the concentration step S41). %).

  “Others” in the component column in Table 5 means elements contained in nickel oxide ores such as nickel, magnesium, chromium, manganese, calcium, cobalt, etc., and neutralizers added when processing nickel oxide ores It is a generic term for various elements such as elements derived from, and is described as the total of analysis values of these detected components. In this embodiment, aluminum and iron are not included in “Others”.

As can be seen from the removal rate results shown in Table 5, aluminum and iron other than scandium and other impurities can be almost completely removed, and the purity as scandium oxide (Sc ₂ O ₃ ) exceeds 99.9% by weight. An extremely high purity scandium oxide could be obtained.

[Comparative Example 1]
In the scandium eluate obtained through the hydrometallurgical treatment step S1 and the scandium elution step S2, the amount of oxalic acid dihydrate added is 1.2 times the calculated amount of scandium contained in the starting solution. The scandium recovery step S5 was performed in the same manner as in Example 1 except that the pH of the solution after addition of oxalic acid was 0. And the quality (purity) of the scandium contained in the scandium oxide after roasting (baking) was measured.

As a result, impurity components including aluminum and iron can be almost completely separated, and the purity as scandium oxide (Sc ₂ O ₃ ) after roasting can be ensured to be 99.9% by weight or more. The actual yield was lower than the method of Example 1 combined with acidification treatment.

  In the case of Comparative Example 1, the scandium eluent contains iron and aluminum in addition to scandium. Therefore, in the scandium recovery step S4, giving priority to the actual yield, when the addition amount of oxalic acid dihydrate and the pH of the solution after the addition of oxalic acid are set to the same conditions as in Example 1, a precipitate of scandium oxalate Iron and aluminum are also included. Therefore, the quality (purity) as high as Example 1 cannot be obtained.

<Test Example 2> Optimization of scandium extraction step S3 [Test Example 2-1] Effect of reduction step S32 In order to verify the effect of reduction step S32, scandium, divalent iron, and trivalent iron of D2EHAG were used. The extraction behavior was investigated.

Several types of sulfuric acid acidic solutions each containing 1 × 10 ⁻⁴ mol / l of scandium, divalent iron, and trivalent iron and adjusted to pH 1.1 to 7.9 were prepared and used as original solutions. In addition, divalent iron was prepared using ferrous sulfate and trivalent iron using ferric sulfate.

  A normal dodecane solution containing 0.01 mol / l of D2EHAG and having the same volume as the above original solution was added to a test tube containing the original solution, placed in a thermostatic chamber at 25 ° C., and shaken for 24 hours. At this time, the pH of the sulfuric acid solution was adjusted to be constant using sulfuric acid, ammonium sulfate and ammonia having a concentration of 0.1 mol / l.

  After shaking, the organic phase was back extracted with 1 mol / l sulfuric acid. And the density | concentration of each component contained in the said original liquid in a back extraction phase was measured using the induction plasma emission spectroscopy analyzer (ICP-AES). From this measurement result, the extraction rate of each component was defined and determined by the amount in the organic phase / (the amount in the organic phase + the amount in the aqueous phase). The results are shown in FIG. The horizontal axis of FIG. 2 is the pH of the sulfuric acid acidic solution, and the vertical axis is the extraction rate (unit:%) of various components contained in the original solution.

  It can be seen from FIG. 2 that the extraction behavior differs between divalent iron and trivalent iron. For acidic solutions containing scandium and divalent iron, the organic phase containing scandium and divalent iron are contained by performing solvent extraction with D2EHAG while adjusting the pH to 1.2 to 4.5. The water phase can be separated.

  On the other hand, for the acidic solution containing scandium and trivalent iron, in the region where scandium can be extracted into the organic phase, trivalent iron is also extracted into the organic phase, so for the acidic solution containing scandium and trivalent iron, Solvent extraction with D2EHAG cannot be performed.

  Therefore, in order to efficiently remove iron ions contained in the original solution, prior to performing the scandium extraction process S33 using D2EHAG, a reduction step S32 for reducing the trivalent iron contained in the original solution to divalent iron is performed. It is preferable.

[Test Example 2-2] Optimum pH of scandium pre-extraction original solution (extraction start solution) in scandium extraction step S33
A hydrometallurgical treatment step S1, a scandium elution step S2, an impurity extraction step S3, and a reduction step S32 were performed in the same manner as in Example 1. Through these steps, a scandium pre-extraction original solution having the composition shown in Table 6 was obtained.

The scandium extraction step S33 using an organic solvent containing D2EHAG was performed on the original scandium extraction solution (extraction start solution) having the composition shown in Table 6. As in Example 1, the organic solvent is SWAZOL 1800 manufactured by Maruzen Petroleum Corporation, and the concentration of D2EHAG is 20% by volume. The organic amount (O) and the amount of the extraction starting liquid (A) were set to O / A = 2, and the extraction equilibrium pH was selected as the extraction conditions shown in Table 7.

  FIG. 3 is a graph showing the results of extraction rates (%) of Sc, Al, and Fe (II) contained in the organic solvent (organic phase) after solvent extraction. The extraction rate was a percentage of a value obtained by dividing the amount of each element contained in the extracted organic phase by the amount of each element contained in the original solution before extraction.

  As can be seen from the graph of FIG. 3, when the pH is 1.0, scandium and other impurities can be efficiently separated, and as a result, scandium is selectively extracted into an organic solvent after extraction. I found out that I could do it. Specifically, when the pH was 1.0, the scandium extraction rate was 56%, whereas the impurity extraction rate was less than 3%.

  In order to efficiently recover scandium from an acidic aqueous solution containing scandium and impurities (mainly divalent iron and aluminum), the pH of the acidic aqueous solution containing scandium is 2.5 or less, more preferably 1. It was confirmed that it is preferable to add the organic solution of the extractant while adjusting to 5 or less.

Test Example 2-3 Optimal Concentration of Sulfuric Acid Used in Scandium Back Extraction Step S34 The organic phase obtained in Test Example 2-2-1 was mixed with sulfuric acid and subjected to the back extraction step S34. Table 8 shows the concentration conditions of sulfuric acid used for back extraction.

  FIG. 4 is a graph showing the relationship between the concentration of scandium used for back extraction and the back extraction rate of scandium. Here, the back extraction rate refers to the proportion of the metal that has been separated from the organic solvent and contained in the sulfuric acid.

  From the graph of FIG. 4, it was confirmed that the sulfuric acid concentration is preferably 1 mol / L or more in order to obtain a high yield.

S1 Hydrometallurgical treatment process S2 Scandium elution process S3 Scandium extraction process S4 Scandium recovery process

Claims (6)

An adsorption step of passing a solution containing scandium through an ion exchange resin and adsorbing the scandium to the ion exchange resin;
An elution step of passing a sulfuric acid solution through the ion exchange resin, eluting the scandium from the ion exchange resin, and obtaining a liquid after elution;
After the elution step, the solution containing scandium is subjected to solvent extraction using a scandium extractant containing an amide derivative, and separated into an aqueous phase containing impurities and an organic phase containing scandium. A scandium recovery method comprising: A concentration step of concentrating the post-elution solution after the elution step;
The scandium recovery method according to claim 1, wherein the impurity extraction step is performed after the concentration step. The post-elution solution contains trivalent iron as an impurity,
After the elution step, further comprising a reduction step of reducing the trivalent iron contained in the scandium-containing aqueous phase to divalent iron,
The scandium recovery method according to claim 1 or 2, wherein the scandium extraction step is performed after the reduction step. A scandium back extraction step of subjecting the organic phase containing scandium to back extraction to obtain a scandium back extract;
After the scandium back extraction step, a precipitation step of adding oxalic acid to the scandium-containing solution to precipitate scandium oxalate;
An oxidation step of oxidizing the scandium oxalate to obtain scandium oxide,
The scandium recovery method according to any one of claims 1 to 3, wherein the pH of the solution when oxalic acid is added to the solution containing scandium is 0 or more and 1.0 or less. The scandium recovery method according to any one of claims 1 to 4, wherein the amide derivative is represented by the following general formula (I).

(In Formula (I), R ¹ and R ² each represent the same or different alkyl group. The alkyl group may be linear or branched. R ³ represents a hydrogen atom or an alkyl group. R ⁴ represents A hydrogen atom or an arbitrary group other than an amino group bonded to the α-carbon as an amino acid is shown.)   The scandium recovery method according to any one of claims 1 to 5, wherein the solution passed through the ion exchange resin in the adsorption step is an acid solution obtained by leaching nickel oxide ore with sulfuric acid under high temperature and high pressure.

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