JP6172099B2 - Scandium recovery method - Google Patents

Description

  The present invention relates to a scandium recovery method, and more particularly to a scandium recovery method for easily and efficiently recovering scandium contained in nickel oxide ore using solvent extraction with an amine-based extractant.

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

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

  However, in recent years, an HPAL process has been put into practical use, in which nickel oxide ore is charged together with sulfuric acid into a pressure vessel and heated to a high temperature of about 240 ° C. to 260 ° C. to separate into solid and liquid leachate containing nickel and leach residue. ing. 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.

  However, it is known that the nickel oxide ore described above may contain an actinide element such as thorium. In this case, in the chelate resins and organic solvents disclosed in Patent Document 2 and Patent Document 3, many actinoid elements exhibit behavior similar to scandium, and it is difficult to separate from scandium. In addition, the nickel oxide ore leachate contains impurities such as iron and aluminum at the same time and at a higher concentration. Due to the effects of these large amounts of impurities, high purity scandium from nickel oxide ore is industrially produced. No suitable method has been found for recovery.

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

  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 that can easily and efficiently recover high-quality 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-quality scandium from nickel oxide ore by subjecting an acidic solution containing scandium and thorium, an actinoid element, to solvent extraction using an amine-based extractant. The present inventors have found that this can be done and have completed the present invention. That is, the present invention provides the following.

  (1) A first invention of the present invention is a scandium recovery method in which nickel oxide ore is leached with sulfuric acid, the obtained leachate is passed through an ion exchange resin, and then scandium is recovered through a solvent extraction process. In the solvent extraction treatment, by using an amine-based extractant as an extractant for solvent extraction, thorium contained in the solution to be treated is extracted into the extractant, and scandium remaining in the solution to be treated after extraction is extracted. It is a method for recovering scandium characterized by separating.

  (2) Further, in the second invention of the present invention, in the first invention, the extractant after extracting thorium in the solution to be treated is added to 1.0 mol / l or more and 3.0 mol / l as a cleaning liquid. A method for recovering scandium characterized by mixing a sulfuric acid solution having a concentration of 1 or less, performing scrubbing to separate scandium contained in the extractant into the cleaning liquid, and recovering scandium from the scrubbing cleaning liquid. .

  (3) Further, in the third invention of the present invention, in the first invention, the extractant after back extraction and the back extract are obtained by performing reverse extraction by adding carbonate to the extractant after extraction. The thorium extracted in the extractant is separated and recovered in the back extract, and this is a scandium recovery method.

  (4) Further, in the fourth invention of the present invention, in the second invention, the extractant and back extract liquid after back extraction are obtained by adding carbonate to the scrubbing extractant and performing back extraction. The thorium extracted in the extractant is separated and recovered in the back extract, and this is a scandium recovery method.

  (5) The fifth invention of the present invention is characterized in that, in the third or fourth invention, the extractant after back extraction is repeatedly used as an extractant for extracting thorium in the solution to be treated. The scandium recovery method.

  (6) Moreover, the sixth invention of the present invention is the process according to any one of the first to fifth inventions, wherein the solution to be treated is subjected to the nickel oxide ore by sulfuric acid under high temperature and high pressure. A leaching step of leaching to obtain a leachate, a neutralization step of adding a neutralizing agent to the leachate to obtain a neutralized starch containing impurities and a post-neutralization solution, and a sulfidizing agent to the post-neutralization solution A method for recovering scandium, characterized in that it is the post-sulfurized solution obtained by wet smelting treatment of nickel oxide ore having a sulfiding step of adding nickel sulfide and a post-sulfurized solution.

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

It is a flow figure for explaining the recovery method of scandium concerning the present invention. It is a flow figure for explaining an example of the whole flow to which the recovery method of scandium concerning the present invention was applied. It is a graph which shows the extraction rate of Sc, Th, Al, and Fe contained in the organic solvent after the solvent extraction process in an Example. It is a graph which shows the relationship between the sulfuric acid concentration and the washing | cleaning rate (recovery rate by washing | cleaning) when the sulfuric acid solution as a washing | cleaning liquid is added to the extractant after solvent extraction in an Example, and the scrubbing (washing) process is performed.

  Hereinafter, specific embodiments of the scandium recovery method according to the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. However, the present invention can be implemented with appropriate modifications within a range not changing the gist of the present invention.

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

  In this scandium recovery method, thorium in the acidic solution is extracted into the extractant by subjecting the acidic solution (processed solution) containing scandium and thorium to a solvent extraction process using an amine-based extractant. And separated from scandium which will remain in the acidic solution after extraction. And about the scandium which came to be contained in the extraction residual liquid by solvent extraction, it can be collect | recovered by well-known methods, such as adding oxalic acid and collect | recovering as a deposit, for example.

  As described above, the scandium recovery method according to the present embodiment is characterized by performing a solvent extraction process using an amine-based solvent extractant in separating and recovering scandium by solvent extraction. According to such a method, impurities can be separated with higher quality, stable operation can be performed even from a raw material containing many impurities such as nickel oxide ore, and high quality. Can be efficiently recovered.

  For example, in the scandium recovery method according to the present embodiment, as shown in the flowchart of FIG. 1, nickel is obtained by leaching nickel oxide ore with an acid such as sulfuric acid to obtain an acidic solution containing scandium and thorium. Oxide ore hydrometallurgical treatment step S1, scandium elution step S2 for obtaining scandium eluate in which scandium is concentrated by removing impurities from the acidic solution, and scandium eluent for solvent extraction using an amine-based extractant It is assumed to have a solvent extraction step S3 for extracting thorium into the extractant and separating it from the scandium remaining in the acidic solution after extraction, and a scandium recovery step S4 for recovering scandium from the extracted residue. it can.

≪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 and thorium to be treated 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.

(1) Leaching step In the leaching step S11, for example, using a high-temperature pressurized container (autoclave) or the like, sulfuric acid is added to the slurry of nickel oxide ore, and the mixture is stirred at a temperature of 240 ° C to 260 ° C. It is a step of forming a leaching slurry comprising leaching residues. 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.

(2) Neutralization process Neutralization process S12 adjusts pH by adding a neutralizing agent to the leachate obtained by leaching process S11 mentioned above, and neutralized starch containing an impurity element and the liquid after neutralization It is a process to obtain. 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 process in neutralization process S2, it is preferable to adjust pH to the range of 1-4, suppressing the oxidation of the isolate | separated leachate, and adjusting pH to the range of 1.5-2.5. Is more preferable. 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.

(3) Sulfurization step Sulfurization 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 above-described neutralization step S12. 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, while an aqueous solution. The liquid after sulfidation, which is a 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 nickel oxide ore hydrometallurgical treatment step S1 is subjected to scandium and thorium, which are targets of scandium recovery treatment. Can be used as an acidic solution.

<2-2. Scandium (Sc) elution step>
In the present embodiment, the post-sulfurization solution, which is an acidic solution containing scandium and thorium obtained by leaching nickel oxide ore with sulfuric acid as described above, is applied as the target solution for the scandium recovery treatment. be able to. However, in the post-sulfurization solution that is an acidic solution containing scandium and thorium, in addition to scandium and thorium, aluminum, chromium, and the like remaining in the solution without being sulfided by the sulfurization treatment in the above-described sulfurization step S13 are included. include. Therefore, when this acidic solution is subjected to solvent extraction, as a scandium elution step S2, impurities contained in the acidic solution are removed in advance and scandium (Sc) is concentrated to produce a scandium eluent (scandium-containing solution). It is preferable to make it.

  In the scandium elution step S2, for example, an ion exchange treatment using a chelate resin is 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. Can do.

  In the following, referring to the flow chart of FIG. 2, as 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 taken as an example. However, the present invention is not limited to this method.

  The process shown as an example in FIG. 2 relates to the ion exchange process S2. Specifically, the sulfidized solution obtained in the sulfurization step S13 of the nickel oxide ore hydrometallurgy treatment step S1 is brought into contact with the chelate resin to adsorb the scandium in the sulfidized solution to the chelate resin. ) Eluent is obtained.

  The form of the ion exchange step S2 is not particularly limited. For example, an 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 in which scandium is adsorbed are set to 0.8. An aluminum removal step S22 for removing aluminum adsorbed on the chelate resin by contacting 1N or less of sulfuric acid; a scandium elution step S23 for obtaining a scandium eluent by contacting sulfuric acid of 0.3N or more and 3N or less to the chelate resin; and Examples thereof include 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. Hereinafter, the outline of each process will be briefly described.

[Adsorption process]
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 process]
In the aluminum removal step S22, 0.1 N or less sulfuric acid is brought into contact with the chelate resin that has adsorbed scandium in the adsorption step S21 to remove aluminum adsorbed on the chelate resin. In addition, when removing aluminum, it is preferable to maintain pH in the range of 1 or more and 2.5 or less, and it is more preferable to maintain in the range of 1.5 or more and 2.0 or less.

[Scandium elution step]
In the scandium elution step S23, sulfuric acid of 0.3N or more and less than 3N is brought into contact with the chelate resin that has undergone the aluminum removal step S22 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 less than 3N, and more preferably maintained in the range of 0.5N to less than 2N.

[Chromium removal process]
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 chromium, if the normality of sulfuric acid used in the eluent is less than 3N, it is not preferable because chromium is not properly removed from the chelate resin.

<2-3. Solvent extraction process>
Next, in the solvent extraction step S3, the scandium-containing solution obtained in the scandium elution step S2, that is, an acidic solution containing scandium and thorium that is an impurity is brought into contact with the extractant, and an extraction solution containing scandium is obtained. obtain.

  The mode in the solvent extraction step S3 is not particularly limited, but the extraction containing the scandium-containing solution and the organic solvent extractant to extract impurities (thorium) and a small amount of scandium leaves the organic solvent and scandium remaining after extraction. An extraction step S31 for separating into a residual liquid; a scrubbing step S32 for obtaining a post-washing liquid by mixing a sulfuric acid solution in an organic solvent after extraction to separate a small amount of scandium extracted in the organic solvent after extraction into an aqueous phase; It is preferable to perform a solvent extraction process including a back extraction step S33 in which a back extractant is added to the organic solvent after washing and impurities (thorium) are back extracted from the organic solvent after washing.

(1) Extraction step In the extraction step S31, a scandium-containing solution and an organic solvent containing an extractant are mixed to selectively extract impurities (thorium) in the organic solvent, and extracted with an organic solvent containing thorium. The remaining liquid is obtained. The scandium recovery method according to the present embodiment is characterized in that a solvent extraction process using an amine-based extractant is performed in the extraction step S31. By performing solvent extraction using an amine-based extractant, thorium as an impurity can be extracted more efficiently and effectively and separated from scandium.

  Here, the amine-based extractant has characteristics such as low selectivity with scandium and no need for a neutralizing agent during extraction. For example, Primene JM-T, which is a primary amine, secondary amine. An amine-based extractant known under a trade name such as LA-1, a tertiary amine, TNOA (Tri-n-octylamine), or TIOA (Tri-i-octylamine) can be used.

  At the time of extraction, it is preferable to use the amine-based extractant diluted with, for example, a hydrocarbon-based organic solvent. The concentration of the amine-based extractant in the organic solvent is not particularly limited, but is preferably about 1% by volume or more and 10% by volume or less in consideration of phase separation during extraction and back extraction described later, In particular, it is more preferably about 5% by volume.

  Further, the volume ratio between the organic solvent and the scandium-containing solution at the time of extraction is not particularly limited, but the organic solvent molar amount is about 0.01 to 0.1 times the metal molar amount in the scandium-containing solution. It is preferable to make it.

(2) Scrubbing (washing) step In the above-described extraction step S31, when scandium is slightly present in the solvent from which thorium as an impurity is extracted from the scandium-containing solution, the extract obtained in the extraction step S31 Before back-extracting, it is preferable to scrub (wash) the organic solvent (organic phase) to separate the scandium into an aqueous phase and recover it from the extractant (scrubbing step S32).

  In this way, the scrubbing step S32 is provided to wash the organic solvent, and by separating the slight scandium extracted by the extractant, scandium can be separated in the washing liquid, and the recovery rate of scandium is further increased. Can be increased.

  As a solution (cleaning solution) used for scrubbing, a sulfuric acid solution, a hydrochloric acid solution, or the like can be used. Moreover, what added the soluble chloride and sulfate to water can also be used. Specifically, when a sulfuric acid solution is used as the cleaning solution, it is preferable to use one having a concentration range of 1.0 mol / l or more and 3.0 mol / l or less.

  Since the number of cleaning stages (number of times) depends on the type and concentration of the impurity element, it can be appropriately changed depending on each amine-based extractant and extraction conditions. For example, when the phase ratio O / A = 1 of the organic phase (O) and the aqueous phase (A) is set to 1, the scan number extracted in the organic solvent is detected by the analyzer by setting the number of stages to about 3 to 5 stages. Separation can be achieved to below the lower limit.

(3) Back extraction step In the back extraction step S33, impurities (thorium) are back extracted from the organic solvent from which the impurities (thorium) are extracted in the extraction step S31. Specifically, in this back extraction step S33, a reverse extraction solution (back extraction start solution) is added to and mixed with an organic solvent containing an extractant, thereby causing a reaction opposite to the extraction process in the extraction step S31. Thorium is back-extracted to obtain a post-extraction solution containing thorium.

  As described above, in the present embodiment, thorium as an impurity is selectively extracted using an amine-based extractant as an extractant in the extraction process in the extraction step S31. From this viewpoint, from the viewpoint of efficiently and effectively separating thorium as an impurity from an organic solvent containing an extractant to regenerate the extractant, the back-extraction solution includes, for example, carbonates such as sodium carbonate and potassium carbonate. It is preferable to use a solution containing a salt.

  The concentration of the carbonate-containing solution that is the back extraction solution is preferably about 0.5 mol / l to 2 mol / l, for example, from the viewpoint of suppressing excessive use.

  In addition, when the scrubbing process is performed on the organic solvent containing the extractant in the scrubbing step S32 described above, the reverse extraction solution is similarly added to and mixed with the extractant after the scrub. An extraction process can be performed.

  The extractant after adding thorium by adding a carbonate solution such as sodium carbonate to the extractant after extraction or after scrubbing and separating thorium is extracted again in the extraction step S31. It can be used repeatedly as an extractant used for processing.

<2-4. Scandium recovery process>
Next, in the scandium recovery step S4, when scrubbing is performed in the extraction step S31 in the solvent extraction step S3 and the scrubbing step S32, scandium is recovered from the scrubbing cleaning solution. To do.

  The scandium recovery method in the scandium recovery step S4 is not particularly limited, and a known method can be used. For example, oxalic acid is added to the extraction residual liquid and the washing liquid to form a scandium oxalate precipitate, and then the scandium oxalate is dried and roasted to recover it as scandium oxide. it can. In the following, an outline of a method for recovering scandium as scandium oxide by performing a roasting process after oxalate conversion will be described with reference to the flowchart of FIG.

[Oxalization step]
The oxalate formation step S41 is a step in which a predetermined amount of oxalic acid is added to the extraction residual liquid and the washing liquid obtained in the solvent extraction step S2 to precipitate and precipitate as a scandium oxalate solid and separate.

  The amount of oxalic acid added is not particularly limited, but it may be 1.05 to 1.2 times the equivalent amount required for precipitating scandium contained in the extraction residual liquid as oxalate. preferable. If the amount added is less than 1.05 times the equivalent amount required for precipitation, there is a possibility that the entire amount of scandium cannot be recovered. On the other hand, when the amount of addition exceeds 1.2 times the equivalent amount required for precipitation, the solubility of the obtained scandium oxalate increases, so that the scandium is redissolved and the recovery rate decreases, or excess oxalic acid The amount of oxidizing agent such as hypochlorous soda used for decomposing is increased.

[Roasting process]
The roasting step S42 is a step in which the precipitate of scandium oxalate obtained in the oxalate forming step S41 is washed with water and dried, and then roasted. By undergoing the roasting process in this roasting step S42, scandium can be recovered as extremely high-quality 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. In addition, 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.

<Example 1>
[Preparation of scandium-containing solution]
Based on a known method such as the method described in Patent Document 1, nickel oxide ore is subjected to pressure acid leaching using sulfuric acid, the pH of the obtained leachate is adjusted to remove impurities, and then a sulfurizing agent is added. Then, nickel was separated and a solution after sulfidation was prepared. Table 1 shows the composition of the post-sulfurization solution.

  An impurity such as thorium is added to the post-sulfurized solution as necessary with a reagent, an ion exchange treatment using a chelate resin is performed, and a concentration treatment is performed by a known method such as heating to obtain an original solution before extraction. Got. Table 2 shows the composition of the original solution before extraction.

[Solvent extraction]
[Extraction process]
100 liters of the solution having the composition shown in Table 2 was used as the extraction starting solution. This was mixed with 50 liters of an organic solvent adjusted to 5% by volume of an amine-based extractant (manufactured by Dow Chemical Co., Primemine JM-T) using a solvent (manufactured by Shell Chemicals Japan Co., Ltd., Shellsol A150). The mixture was stirred for a minute to obtain a residual extract containing scandium. In addition, no clad was formed during extraction, and phase separation after standing proceeded rapidly.

  The composition of each element contained in the extracted 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, most of the scandium (Sc) contained in the original liquid before extraction was distributed to the extraction residual liquid through the extraction process, and Al, Fe, etc. were not extracted. Was confirmed. Moreover, thorium (Th) contained in the extraction starting liquid was extracted at a high extraction rate.

[Scrubbing (cleaning) process]
Next, a 50 liter organic solvent (extracted organic phase) containing scandium obtained in the extraction step is mixed with a sulfuric acid solution having a concentration of 1 mol / l and 50 liters so that the phase ratio (O / A) is 1. Mix and wash with stirring for 60 minutes. Thereafter, the aqueous phase was separated by standing, and the organic phase was again mixed with 50 liters of a new sulfuric acid solution having a concentration of 1 mol / l and washed, and the aqueous phase was separated in the same manner. Such washing operation was repeated 5 times in total.

  By washing the extracted organic phase 5 times, scandium contained in the extracted organic phase could be separated into the aqueous phase and recovered. On the other hand, the impurities contained in the extracted organic phase remain at a low level of 1 mg / l, and only scandium extracted in the organic solvent can be effectively separated into the aqueous phase, and only the impurities can be removed. I understood.

[Back extraction process]
Next, sodium carbonate having a concentration of 1 mol / l is mixed in the extracted organic phase after washing so as to have a phase ratio of O / A = 1/1, and stirred for 60 minutes to give a back extraction treatment. (Thorium) was back extracted into the aqueous phase.

  The composition of various elements contained in the liquid after back extraction obtained by this back extraction operation was analyzed. In Table 4, the percentage of the value of each element contained in the liquid after back extraction divided by the quantity of each element extracted in the organic phase in the extraction step is calculated, and the result is obtained as the recovery rate (%). Show.

  As can be seen from the results of the recovery rates shown in Table 4, by performing the solvent extraction process described above, thorium contained in the original liquid before extraction is separated, and scandium that can be recovered from the extracted residual liquid and the liquid after washing, It was confirmed that high purity scandium could be obtained by separation.

<Example 2>
The post-sulfurization solution having the same composition shown in Table 1 used in Example 1 is subjected to ion exchange treatment and concentration treatment by the same method as in Example 1, and the obtained scandium hydroxide is dissolved again with sulfuric acid. Thus, a chelate eluent (hydroxide solution) having the composition shown in Table 5 was obtained and used as the original solution before solvent extraction.

  A chelate eluent (hydroxide solution) having the composition shown in Table 5 was used as an extraction start solution, and subjected to solvent extraction using an amine-based extractant. As in Example 1, Primemine JM-T (manufactured by Dow Chemical Company) was used as the amine-based extractant, and this was diluted to 5% with a solvent (manufactured by Shell Chemicals Japan, Shellzol A150). The extraction equilibrium pH was set to 1, and the amounts of organic amount (O) and starting extraction solution (A) were selected as shown in Table 6 based on the ratio of the organic amount to the metal amount in the solution.

  FIG. 3 is a graph showing the results of extraction rates (%) of Sc, Th, U, Al, and Fe contained in the organic solvent. 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 organic amount / metal amount (unit: mol / mol, hereinafter the same), which is the ratio of the organic amount to the metal amount, is in the range of 0.01 to 0.1, the amine It was found that thorium can be efficiently separated from scandium by solvent extraction using a system extractant, and as a result, scandium can be concentrated in the extracted residue. Specifically, when O / A is 0.5 (organic amount / metal amount = 0.02), the extraction rate of thorium is 50%, whereas the extraction rate of scandium is 4%.

  In addition, it is not preferable that the organic amount / metal amount is less than 0.01 times because the phase separation between the organic phase and the aqueous phase is poor. On the other hand, when the organic amount / metal amount exceeds 0.1 times, the organic phase contains a large amount of scandium, which is not preferable.

  Subsequently, sulfuric acid was mixed with the organic solvent after extracting scandium according to Example 2-3 and washed. Table 7 shows the concentration conditions of sulfuric acid used for washing.

  FIG. 3 is a graph showing the relationship between the concentration of sulfuric acid used for cleaning and the cleaning rate. Here, the washing rate refers to the proportion of the metal that has been separated from the organic solvent and contained in the sulfuric acid.

  As can be seen from the graph of FIG. 3, scandium could be separated and recovered from the organic solvent at any sulfuric acid concentration, but particularly when the sulfuric acid concentration was 1 mol / l or more and 3 mol / l or less. While only thorium was left in the organic solvent, only scandium could be efficiently separated and recovered from the organic solvent.

Claims (6)

In the scandium recovery method of leaching nickel oxide ore with sulfuric acid, passing the obtained leachate through an ion exchange resin, and then recovering scandium through solvent extraction treatment,
In the solvent extraction treatment, by using an amine-based extractant as an extractant for solvent extraction, thorium contained in the solution to be treated is extracted into the extractant, and scandium remaining in the solution to be treated after extraction is extracted. A method for recovering scandium characterized by separating.   A sulfuric acid solution having a concentration of 1.0 mol / l or more and 3.0 mol / l or less as a cleaning liquid is mixed with the extractant after extracting thorium in the solution to be treated, and scandium contained in the extractant is added to the extractant. 2. The method for recovering scandium according to claim 1, wherein scrubbing is performed in the cleaning liquid, and scandium is recovered from the cleaning liquid after scrubbing.   Extraction agent and back extract after back extraction are obtained by adding carbonate to the extract after extraction and back extraction, and thorium extracted in the extraction agent is separated into back extract and recovered The method for recovering scandium according to claim 1, wherein:   Extraction agent and back extract after back extraction are obtained by adding carbonate to scrubbing extract and back extraction, and thorium extracted in the extract is separated and recovered in back extract The method for recovering scandium according to claim 2.   The method for recovering scandium according to claim 3 or 4, wherein the extractant after back extraction is repeatedly used as an extractant for extracting thorium in the solution to be treated. The solution to be treated subjected to the solvent extraction treatment is
A leaching step of leaching the nickel oxide ore with sulfuric acid under high temperature and high pressure to obtain a leachate;
A neutralization step of obtaining a neutralized starch containing impurities and a neutralized solution by adding a neutralizing agent to the leachate;
A sulfidizing agent is added to the post-neutralized liquid to obtain a nickel sulfide and a post-sulfurized liquid, and is a post-sulfurized liquid obtained by a hydrometallurgical treatment of nickel oxide ore. Item 6. The method for recovering scandium according to any one of Items 1 to 5.

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