JP2021137702A - Oil separator and refining method of scandium using the same - Google Patents

Abstract

To provide an oil separator where oil content in oil-mixed water and foreign matter such as suspended matter, amorphous residue and the like can be reduced to a very low level and operation can be stably performed.SOLUTION: An oil separator treating oil-mixed water containing suspended matter comprises: a clarifier 2 removing oil content and foreign matter from the oil-mixed water; a coalescer 30 removing the oil content from the oil-mixed water supplied from the clarifier 2; a second activated carbon adsorption tower 40 removing the oil content from the oil-mixed water supplied from the coalescer 30; and a hollow fiber membrane filter 50 removing fine foreign matter from the oil-mixed water supplied from the second activated carbon adsorption tower 40. Impurities can be reduced to a ppm level or less though being an aqueous phase having a lot of suspended matter and amorphous residues and high purity scandium can be refined.SELECTED DRAWING: Figure 1

Description

The present invention relates to an oil-water separator and a scandium purification method using the same. More specifically, the present invention relates to an oil-water separator for treating oil-containing mixed water containing oil and suspended solids, and a scandium purification method using the same.

As a method of refining (smelting) a metal such as nickel from a raw material such as oxide ore, the ore as a raw material is leached with an acid or the like to obtain an acidic leachate containing nickel, and this leachate is used as an electrolytic solution. There is a method of obtaining a metal to be recovered such as nickel by electrowinning.

However, the raw material often contains a wide variety of impurities other than the metal to be recovered, which are not suitable for recovery or affect the quality of the target metal, and the above-mentioned leachate is often used for electrowinning prior to electrowinning. It is necessary to separate impurities by subjecting them to the purification process.

There are various methods for the purification step, and among them, for example, a solvent extraction method in which the above-mentioned acidic leachate is brought into contact with an organic solvent containing an extractant to separate a target metal or impurity in the leachate is widely used. ..

The solvent extraction method is generally performed through three steps of extraction, washing, and back extraction.
The organic solvent used is an extractant that acts on the extraction diluted with a diluent.
At the extraction stage, the organic solvent and the liquid to be treated (the leachate in the refining step or the acid leachate) are mixed, and the metal ions in the liquid to be treated are transferred (extracted) to the organic solvent. At this time, the liquid that has not been transferred to the solvent remains in the "liquid to be treated after extraction" (also referred to as "drawing residual liquid"). When left to stand here, the liquid to be treated (aqueous phase) and the organic solvent (organic phase) are separated into an organic phase on the upper side and an aqueous phase on the lower side due to the difference in specific gravity. Each "solution" is collected.

In the subsequent washing (also referred to as "scrubbing"), in order to remove the liquid to be treated remaining in the organic solvent, an acid solution or water is mixed with the organic solvent after extraction, stirred, allowed to stand, separated and organic. Wash the solvent.
In the final back extraction (also referred to as "stripping"), a new (metal ion-free) acid solution is added to the washed organic solvent and stirred. In this back extraction, the metal ions extracted in the organic solvent are transferred (back-extracted) from the extractant to the acid solution.

When the back extraction is completed, the acid solution (aqueous phase) containing the target metal ion and the organic solvent (organic phase) that exhales the metal ion and returns to the same state as the first are formed, and both are allowed to stand and separated. ..
However, in reality, even if the organic phase and the aqueous phase are separated by standing still, they cannot be completely (ideally) separated. Therefore, some organic solvents are dissolved and mixed in water, and the impurities contained in them are oxidized by the influence of agitation. (Called) may occur.

Therefore, the aqueous phase that has completed the solvent extraction step is actually an oil-mixed water in which a small amount of oil is mixed, although it is called an aqueous phase.
If the mixed water containing oil is continued in the subsequent process as it is, it may affect the product quality, and if it is discharged to the sea area through the wastewater treatment process, it may affect the environment, which is preferable. No.
Therefore, it is industrially indispensable to supply the above-mentioned oil-mixed water to the oil-water separation device to remove the oil.

The prior art of Patent Document 1 is an oil-water separation device for treating oil-mixed water containing suspended solids, which is a decontamination device for removing suspended solids from the oil-mixed water and an oil-mixed water discharged from the decontamination device. Is equipped with a coalesser to be supplied. Even if the oil-mixed water contains suspended solids, it is supplied to the corelesser after the suspended solids are removed by the decontamination device, so it is possible to prevent the suspended solids from adhering to the filter of the corelesser, and the oil-water separation performance There is an advantage that the decrease can be prevented.

However, in the solvent extraction method in which an acid is added to the ore to leach the metal to be recovered and purified by using solvent extraction, the oil mixed water obtained in the solvent extraction step may contain a suspended substance. be. Especially in the industrial process of leaching metal from ore and refining it, a large amount of liquid is often handled, and the ore also contains a large amount of impurity components such as _{iron, aluminum, manganese, silica (SiO 2) and calcium.} Therefore, some of these impurity components are leached into the acid solution together with the metal to be recovered such as nickel, and are oxidized during the treatment to become oxides, which often generate a large amount of suspended substances.

Further, in the solvent extraction treatment, an amorphous residue called a clad may be generated between the organic solvent (oil phase) and the liquid to be treated (aqueous phase). The clad is a state in which the organic phase and the aqueous phase are physically mixed. When the clad is generated, the solvent extraction process is stopped and filtration is performed to remove the clad, or if the clad cannot be completely removed, an organic extractant is used. There is a problem that processing such as replacement is required, which increases cost and labor.
As described above, in the solvent extraction step, a large amount of suspended solids were generated, and there were many opportunities for clad to be generated, so that stable operation was not easy.

Further, in recent years, depending on the metal to be recovered, it has become necessary to reduce even the impurity component derived from the suspended solids. For example, it is known that the above-mentioned nickel oxide ore also contains a trace amount of scandium, but when this scandium is to be recovered and used as an electrolyte material for a fuel cell, the impurity level is set to several ppm. An ultra-high purity scandium compound that suppresses from (parts per million) to the level of ppb (parts per billion) is required depending on the component, and it is also necessary to reduce suspended substances as much as possible from the viewpoint of product quality. .. However, it was not easy to stably reduce impurities down to the ppb level by the method of Patent Document 1.

Japanese Unexamined Patent Publication No. 2014-124039

In view of the above circumstances, it is an object of the present invention to provide an oil-water separation device capable of reducing oil content in oil-mixed water and foreign substances such as suspended solids and amorphous residues to a very low level and capable of stable operation. .. Another object of the present invention is to provide a method for purifying scandium using the oil-water separator.

The oil-water separator of the first invention is an oil-water separator that treats oil-mixed water containing foreign substances such as suspended solids, and is a turbidizer for removing oil and foreign substances from the oil-mixed water, and the removal. A corelesser for removing oil from the oil mixed water supplied from the turbidizer, a second activated carbon adsorption tower for removing oil from the oil mixed water supplied from the corelesser, and the second activated charcoal adsorption tower. It is characterized by comprising a hollow fiber membrane filter for removing oil and fine foreign matter from the oil mixed water supplied from the water.
The oil-water separation device of the second invention is characterized in that, in the first invention, the hollow fiber membrane filter uses a filter medium having a pore diameter of 1 nm or more and 100 nm or less.
The oil-water separation device of the third invention is characterized in that, in the first or second invention, the decontamination device comprises a first activated carbon adsorption tower and a cartridge filter provided downstream thereof.
The oil-water separator of the fourth invention is characterized in that, in the first, second or third invention, the oil-containing mixed water is an aqueous phase obtained by solvent extraction from a leachate obtained by leaching ore with an acid.
The scandium purification method of the fifth invention is characterized in that scandium is obtained by using the oil-water separation device according to claim 1, 2 or 3.

According to the first invention, even if suspended solids are contained in the oil-containing mixed water, the decontamination device can remove foreign substances and oils including suspended solids and amorphous residues, and the corelesser can further remove the oils. Further, since the oil content can be further removed by the second activated carbon adsorption tower and then the oil content and fine foreign substances can be removed by the hollow fiber membrane filter, the impurity component derived from the oil content and suspended solids can be reduced to a very low level. Moreover, by arranging the decontamination device, the corelesser, the second activated carbon adsorption tower, and the hollow fiber membrane filter in this order, the upstream equipment can reduce the burden on the downstream equipment and stabilize the removal of impurities to a very low level. And now you can do it.
According to the second invention, since the pore size of the filter medium is 100 nm or less, suspended solids and amorphous residues can be reduced to fine particles, and since it is 1 nm or more, clogging is less likely to occur.
According to the third invention, the oil contained in the oil-mixed water can be adsorbed by the first activated carbon adsorption tower, and foreign substances such as suspended solids and amorphous residues can be removed by the cartridge filter. Therefore, since most of the oil content and the foreign matter can be removed in the front stage of the oil-water separation device, the oil content and the fine foreign matter can be efficiently removed in the rear stage.
According to the fourth invention, foreign matter can be reduced to a level of less than ppm even though it is an aqueous phase in which fine suspended solids and amorphous residues remain in addition to the oil content.
According to the fifth invention, by using the oil-water separator of the first invention, the second invention or the third invention, impurities can be removed to the level of less than ppm in free organic, so that the purity is suitable for the electrolyte material of the battery. Scandium can be obtained.

It is explanatory drawing of the oil-water separation apparatus 1 which concerns on one Embodiment of this invention.

Next, an embodiment of the present invention will be described with reference to the drawings.
The oil-water separation device of the present invention can be used for oil-water separation in all industrial fields. In the following embodiment, a case where it is used for treating an aqueous phase obtained in a solvent extraction step such as nickel refining will be described as an example.

As shown in FIG. 1, in the solvent extraction step, the organic solvent (oil-based) and the liquid to be treated (aqueous) are mixed and then allowed to stand to separate the oil phase and the aqueous phase due to the difference in specific gravity. The liquid to be treated (aqueous) is an aqueous solution containing the target metal, such as an aqueous solution of nickel sulfate, cobalt sulfate, nickel chloride, or cobalt chloride. As an apparatus used in the solvent extraction step, for example, a mixer settler type extraction apparatus is known.

The aqueous phase is an acidic aqueous solution, but is an oil-mixed water in which a small amount of oil (organic solvent) that has not been separated is mixed. Further, the oil mixed water obtained in the solvent extraction step contains foreign substances such as suspended solids and amorphous residues. The organic solvent is used in the repeated solvent extraction step.

≪Basic configuration≫
As shown in FIG. 1, the oil-water separation device 1 according to the embodiment of the present invention includes a turbidity device 2, a corelesser 30, a second activated carbon adsorption tower 40, and a hollow fiber membrane filter 50. They are connected in series in this order from upstream to downstream. In the illustrated oil-water separation device 1, the decontamination device 2 includes a first activated carbon adsorption tower 10 and a cartridge filter 20.

≪Configuration and function of each component device≫
The configurations and functions of each component device will be described below.
(1st activated carbon adsorption tower 10)
The first activated carbon adsorption tower 10 is filled with activated carbon 11. Activated carbon is a carbon substance provided with an extremely large number of pores, and can adsorb and remove fine oil droplets and water-soluble oil by the physical adsorption action of the pores, and can adsorb and remove various foreign substances.

(Cartridge filter 20)
As the cartridge filter 20, various filter exchangeable filters are used. A typical example is a filter sheet bent into a pleated shape to form a cylinder. This type of filter collects foreign matter as it passes through the eyes of the filter sheet. In the present invention, it is mainly used for removing foreign substances such as suspended solids and amorphous residues in oil-mixed water.

(Corelesser 30)
The corelesser 30 is a device that passes oil-mixed water through a filter, captures minute oil droplets with a filter, agglomerates and coarsens the oil droplets, and separates the oil-water by the difference in specific gravity. The purpose of the present invention is to remove the oil that has not been completely removed by the first activated carbon adsorption tower 10 and separate it from the aqueous phase.

(2nd activated carbon adsorption tower 40)
The second activated carbon adsorption tower 40 is a device that is filled with activated carbon 41 like the first activated carbon adsorption tower 10 and removes minute oil droplets and water-soluble oil components. The corelesser 30 is provided to remove oil that has not been completely separated and to reduce the supply of oil and foreign matter to the downstream hollow fiber membrane filter 50 as much as possible. At the stage of passing through the second activated carbon adsorption tower 40, oil, suspended solids and amorphous residues are removed to a considerable extent.

(Hollow fiber membrane filter 50)
The hollow fiber membrane filter 50 is a filter that collects fibers whose central portion is hollow (straw-shaped) and uses them as a filter medium, and is porous with a large number of fine pores on the fiber surface. When raw water passes through this hollow fiber membrane, a small amount of foreign matter can be collected.
In the present invention, it is used to adsorb and remove a trace amount of oil and foreign matter contained on a filter by using an ultrafine hollow fiber membrane. The hollow fiber membrane has a microfiltration membrane with separation performance at the nanometer (nm) level, and if foreign substances such as suspended solids can be removed up to this class, it can be sufficiently used for ultra-high purity product applications. Further, in the hollow fiber membrane filter 50, in addition to being able to effectively adsorb and separate a trace amount of oil contained on the filter, the filter also has a characteristic of being less likely to be clogged, so that it is also very effective in removing oil.

The material of the filter medium fiber used for the hollow fiber membrane filter 50 is not particularly limited, and any material can be used. The pores on the surface of the filter medium preferably have a pore diameter capable of collecting particles having a size of 100 nm. With a filter having a pore size exceeding 100 nm, the hollow fiber membrane filter cannot collect the filter, the turbidity (TSS) increases, and it becomes difficult to maintain the quality. Therefore, the upper limit is preferably 100 nm or less. On the other hand, if the pore diameter becomes extremely small, blockage is likely to occur, so the lower limit is preferably about 1 nm or more.

≪Technical significance of sequence order≫
The reason why the first activated carbon adsorption tower 10 is arranged in the uppermost stream is that when the oil mixed water containing suspended solids is supplied to the corelesser 30 as it is, the suspended solids adhere to the surface layer of the filter and the filter is physically blocked. This is to prevent this because it may end up.

Since the cartridge filter 20 is provided directly below the first activated carbon adsorption tower 10, foreign substances such as suspended solids that could not be completely removed by the first activated carbon adsorption tower 10 can be removed. Further, even if the activated carbon leaks from the first activated carbon adsorption tower 10, it can be captured by the cartridge filter 20 and the adverse effect on the corelesser 30 can be prevented.

Since the decontamination device 2 (first activated carbon adsorption tower 10 and cartridge filter 20) and the corelesser 30 primary remove the oil content in the oil-mixed water, the oil content burden on the second activated carbon adsorption tower 40 is reduced. .. Then, since the oil content is reduced, the water-soluble oil can be further removed by the second activated carbon adsorption tower 40, and the TOC concentration (total organic carbon concentration) can be reduced.

The reason why the second activated carbon adsorption tower 40 is arranged upstream of the hollow fiber membrane filter 50 is to sufficiently secure the function of the hollow fiber membrane filter 50.
That is, when the filter of the hollow fiber membrane filter 50 is closed, the oil-water separation performance of the hollow fiber membrane filter 50 is deteriorated, and the frequency of replacing the closed filter of the hollow fiber membrane filter 50 is increased. The effort will increase.
If the oil content is removed in advance in the second activated carbon adsorption tower 40 as in the present embodiment, the burden on the hollow fiber membrane filter 50 becomes lighter, and fine suspended solids and amorphous residues are reduced to a very low level. Can be removed.

If only the quality of the aqueous solution discharged from the oil-water separation device 1 is to be ensured, it seems that the liquid should be passed through the hollow fiber membrane filter 50 from the beginning, but the solution obtained by processing the raw material ore is used. Due to the presence of a large amount of coarse suspended solids, it quickly becomes clogged and cannot be filtered. Moreover, in order to stably remove suspended solids even when the concentration of suspended solids varies depending on the ore composition or the like, it is preferable to perform microfiltration with the hollow fiber membrane filter 50 in the final stage in order to stabilize the operation.

≪Usage in solvent extraction process≫
As shown in FIG. 1, the oil-mixed water obtained in the solvent extraction step is first supplied to the first activated carbon adsorption tower 10, and the contained oil and foreign matter are adsorbed and removed. The oil mixed water supplied from the first activated carbon adsorption tower 10 is supplied to the cartridge filter 20, and foreign substances such as suspended solids are further removed. The oil-mixed water supplied from the cartridge filter 20 is supplied to the corelesser 30, the oil is removed, and the oil-water is separated. The oil (organic solvent) discharged from the corelesser 30 is sent back to the solvent extraction step and used again.

On the other hand, the oil mixed water supplied from the corelesser 30 is supplied to the second activated carbon adsorption tower 40, and the water-soluble oil is removed. The treatment liquid discharged from the second activated carbon adsorption tower 40 is further supplied to the hollow fiber membrane filter 50, and the hollow fiber membrane filter 50 removes fine oils and foreign substances such as suspended solids. The post-treatment liquid discharged from the hollow fiber membrane filter 50 is sent to the wastewater treatment step.

With the above configuration, the following advantages can be obtained in this embodiment.
(1) Even if suspended solids are contained in the oil-mixed water, foreign substances such as suspended solids are removed by the first activated carbon adsorption tower 10 and the cartridge filter 20 with most of the oil, and then supplied to the corelesser 30. Foreign matter such as suspended solids can be prevented from adhering to the filter 31 of the corelesser 30, and deterioration of oil-water separation performance can be prevented.

(2) The treated liquid discharged from the second activated carbon adsorption tower 40 is supplied to the hollow fiber membrane filter 50. Therefore, even if there are suspended solids that are too fine to be removed by the activated carbon packed tower or the cartridge filter, they can be removed. That is, in the present invention, impurities can be reduced to the level of ppm (parts per million) or less. Furthermore, stable quality can be ensured against changes in the raw materials to be supplied and variations in operating conditions.

(3) The oil-water separation device 1 of the present embodiment can also be used when recovering a trace amount of scandium contained in nickel oxide ore and using it as an electrolyte material for a battery. The electrolyte material of the battery requires high-purity scandium whose impurity level is reduced to a level of ppm or less. However, in the oil-water separator 1 of the present embodiment, scandium having a purity of about 99.9% can be obtained. Therefore, such a request can be satisfied.

(Other embodiments)
In the embodiment of FIG. 1, the decontamination device 2 is configured by the first activated carbon adsorption tower 10 and the cartridge filter 20. In addition to the above, as the decontamination device, an activated carbon adsorption tower alone, a packed tower such as a sand filter, a filter press, a pressure filter such as a bag filter, a sand filter pond, a membrane filter, a cartridge filter alone, or the like can be used. ..
However, in general, since the suspended solids contained in the oil-containing mixed water obtained in the solvent extraction step have a low concentration, an activated carbon-filled tower or a cartridge filter having a low capacity and easy handling is adopted as in the present embodiment. Is preferable.

Next, an embodiment will be described.
In both the examples and the comparative examples, in the solvent extraction step, operations satisfying the following conditions were performed.
<Liquid to be treated>
A sulfuric acid acidic solution having a scandium concentration of 10 g / L was used as the liquid to be treated for solvent extraction. It also contained impurities such as iron, chromium and aluminum.

<Organic solvent>
As the organic solvent in the solvent extraction step, a solvent having an amine functional group (manufactured by Cognis, trade name: Primene JM-T) was used, and the mixture was diluted with a diluent (trade name: Wasol).
The pH of the above-mentioned solution to be treated (sulfuric acid acidic solution, that is, acid leachate) was adjusted with a sodium hydroxide solution having a NaOH concentration of 200 g / L, and the solution was mixed with the above-mentioned organic solvent.

<Extractor>
A mixer settler type brewing device was used as the brewing device. The above liquid to be treated (acidic sulfuric acid solution) was passed through the liquid at a flow rate of about 130 liters / minute and subjected to solvent extraction to obtain an aqueous phase and an oil phase on the discharge side. The oil phase / aqueous phase ratio in solvent extraction was set to 1/3. Extraction was performed at room temperature.

The suspended solids concentration of the oil-mixed water (aqueous phase) obtained in the solvent extraction step was in the range of 10 to 13 mg / L when measured by the method of increasing the weight of the filter paper by filtration.

(Example 1)
The oil-mixed water obtained in the above solvent extraction step was oil-water separated using the oil-water separation device 1 shown in FIG.
The first activated carbon adsorption tower 10 is filled with 360 kg of activated carbon having a particle size of 0.5 to 1.7 mm, and oil-mixed water is passed at a flow rate of 10.8 / hour per unit time (space velocity: SV). Liquid.
For the cartridge filter 20, an apparatus having a pore diameter of 10 μm was used.
As the filter of the corelesser 30, a bundle of 12 filter elements having a diameter of 150 mm, a height of 480 mm, and a filtration hole diameter of 2 μm was used.
The second activated carbon adsorption tower 40 is filled with 360 kg of activated carbon having the same particle size of 0.5 to 1.7 mm as that of the first activated carbon adsorption tower 10, and the oil mixed water discharged from the corelesser 30 is flowed per unit time (space velocity). : SV) was passed at a flow rate of 10.8 (L / h).
Further, for the hollow fiber membrane filter 50, a trade name character manufactured by Kuraray Co., Ltd. equipped with a filter having a pore diameter of 17 nm was used.

(Comparative Example 1)
Oil-water separation was performed using the same apparatus as in Example 1 except that the hollow fiber membrane filter 50 was not used.

The results are shown in Table 1. The turbidity was measured using a commercially available turbidity meter and used as an index of amorphous residue in the solution. The unit is the nephelometer turbidity unit (NTU). In addition, the surface condition of the filtered liquid after standing still was visually observed.

In Example 1, it was confirmed that the turbidity and the contained organic matter were significantly reduced by passing through the hollow fiber membrane filter 50. In Comparative Example 1 in which the hollow fiber membrane filter 50 was not passed, the organic substance could not be completely removed, but in Example 1, since it could be completely removed, the sulfuric acid root derived from the organic component in the scandium product (SO ₄ ^2- ) It turned out to be useful for suppressing dignity.
Specifically, in the treatment up to the conventional corelesser corresponding to Comparative Example 1, the turbidity was 0.7 and the organic component remained, but in the filtration up to the hollow fiber membrane filter 50 which is Example 1. By attaching, the turbidity was reduced to 0.4 and organic matter could be removed.

Further, in order to confirm the effect of Example 1 in terms of product quality, a liquid that has passed through the hollow fiber membrane filter 50 and an oxalic acid aqueous solution are used as the original liquid and reacted with oxalic acid crystals to generate a scandium oxalate slurry. The quality of scandium oxalate obtained by filtering was confirmed.
Specifically, an aqueous oxalic acid solution having a concentration of 100 g / l was added and reacted at room temperature for 4 hours, and then stirring was continued for 1 hour to promote particle growth of scandium oxalate.
For the impurity grade, the total value of the impurity components detected by the analyzer such as iron, manganese, aluminum, nickel, calcium and silicon was evaluated as the total suspended solids amount (TSS).
As shown in Table 2, by performing the filtration using the hollow fiber membrane filter 50 in Example 1, a large difference was generated in the total impurity grade, the organic odor, and the color of the product, and the effect of Example 1 could be confirmed. ..

The results (60-day test) when the actual operation was performed for 60 days are shown below.
In Example 1, the recovered organic amount did not decrease even on the 60th day from the start of the liquid passing, and the initial recovered organic amount could be maintained. Further, the filter replacement work of the cartridge filter 20 did not occur during the operation of 60 days. These results are supported by the low total suspended solids (TSS) of about 50 ppm.

In Comparative Example 1, the amount of recovered organic material decreased to 44% on the 60th day from the start of passing the liquid. This result is also supported by the high total suspended solids (TSS) of about 600 ppm.

The results of Example 1 above also show that the quality of the obtained scandium is high.

1 Oil-water separation device 2 Decontamination device 10 1st activated carbon adsorption tower 20 Cartridge filter 30 Corelesser 40 2nd activated carbon adsorption tower 50 Hollow fiber membrane filter

Claims (5)

An oil-water separator that treats oil-mixed water containing foreign substances such as suspended solids.
A decontamination device for removing oil and foreign matter from the oil-mixed water,
A corelesser for removing oil from the oil mixed water supplied from the turbidizer, and
A second activated carbon adsorption tower for removing oil from the oil mixed water supplied from the corelesser, and
An oil-water separation device comprising a hollow fiber membrane filter for removing oil and fine foreign substances from the oil-containing mixed water supplied from the second activated carbon adsorption tower. The oil-water separation apparatus according to claim 1, wherein the hollow fiber membrane filter uses a filter medium having a pore diameter of 1 nm or more and 100 nm or less. The oil-water separation device according to claim 1 or 2, wherein the decontamination device includes a first activated carbon adsorption tower and a cartridge filter provided downstream thereof. The oil-water separation apparatus according to claim 1, 2 or 3, wherein the oil-mixed water is an aqueous phase obtained by solvent extraction from a leachate obtained by leaching ore with an acid. A scandium refining method, which comprises obtaining scandium using the oil-water separator according to claim 1, 2 or 3.

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