CA1262635A - Method for recovering gallium - Google Patents
Method for recovering galliumInfo
- Publication number
- CA1262635A CA1262635A CA000486230A CA486230A CA1262635A CA 1262635 A CA1262635 A CA 1262635A CA 000486230 A CA000486230 A CA 000486230A CA 486230 A CA486230 A CA 486230A CA 1262635 A CA1262635 A CA 1262635A
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- Prior art keywords
- gallium
- polymer
- quinolinol
- liter
- mol
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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Abstract
ABSTRACT OF THE DISCLOSURE
A method for recovering gallium from an aqueous solution containing gallium, which comprises contacting the aqueous solution containing gallium to a porous polymer having a water-insoluble substituted quinolinol retained therein, to let the polymer adsorb gallium, and then eluting gallium from the polymer.
A method for recovering gallium from an aqueous solution containing gallium, which comprises contacting the aqueous solution containing gallium to a porous polymer having a water-insoluble substituted quinolinol retained therein, to let the polymer adsorb gallium, and then eluting gallium from the polymer.
Description
2~
. . .
TITLE OF THE IMVENTION
METHOD FOR RECOVERING GALIIUM
BACKGROUND OF THE INVENTION
FIELD OF TEIE INVENTION
The present invention relates to a method for recovering gallium. More particularly, it relates to a method for advantageously recovering gallium from a strongly basic aqueous solution such as an aqueous sodium aluminate solution formed by a Bayer process.
DESCRIPTION OF THE PRIOR ART
. It is known that gallium is contained in bauxite in an amount of from 0.002 to 0.01%. In the process for the production of alumina by a Bayer process, an alkali is recycled for repeated use, and a substantial amount of gallium is con-tained in the aqueous sodium aluminate solution formed in this process. An amalgamation method has been known as a method for recovering gallium from the aqueous sodium aluminate solution formed by this Bayer process. In recent years, a liquid-liquid extraction method has been developed as a superior method which will take the place of the amalgamation method.
According ~o this method, gallium is extracted from the aqueous sodiu}n aluminate solution containing gallium by means of an extracting agent prepared by dissolving a water-insoluble substituted quinolinol such as 7-(1-vinyl-3,3,5,5-tetramethylhexyl)-8-quinolinol in an .
organic solvent, ~nd then the extracting agent containing gallium is reverse]y extracted with an aqueous acid solution to recover gallium (Japanese Unexamined Patent Publication No. 32~11/1976). This method is practically useful as an industrial method, but it has a drawback that the substituted quinolinol in the extracting agent is susceptible to degradation. As a method for overcoming this drawback, there has been proposed a method wherein a quinolinol substituted by an alkyl group instead of the alkenyl group is used (Japanese Unexamined Patent Publication No. 52289/1978), or a me-thod wherein the operation is conducted in an inert atmosphere (Japanese Unexamined Patent Publication No. 40212/1979).
SUMMARY OF THE INVENTION
The present inventors have conducted a research to develop a method for recovering gallium in an industrially more advantageous manner than these liquid-liquid extraction methods, and as a result, have found that when the water-insoluble substituted quinolinol used in these liquid-liquid extraction methods is supported on a porous polymer, such a porous polymer exhibits excellent adsorptivity for gallium. Further, it has been unexpectedly found that the substituted quinolinol fixed in this porous polymer does not undergo degradation very much even if repeatedly used for the recovery of gallium from the aqueous sodium aluminate solution. The presént invention has been accomplished on the basis oE this
. . .
TITLE OF THE IMVENTION
METHOD FOR RECOVERING GALIIUM
BACKGROUND OF THE INVENTION
FIELD OF TEIE INVENTION
The present invention relates to a method for recovering gallium. More particularly, it relates to a method for advantageously recovering gallium from a strongly basic aqueous solution such as an aqueous sodium aluminate solution formed by a Bayer process.
DESCRIPTION OF THE PRIOR ART
. It is known that gallium is contained in bauxite in an amount of from 0.002 to 0.01%. In the process for the production of alumina by a Bayer process, an alkali is recycled for repeated use, and a substantial amount of gallium is con-tained in the aqueous sodium aluminate solution formed in this process. An amalgamation method has been known as a method for recovering gallium from the aqueous sodium aluminate solution formed by this Bayer process. In recent years, a liquid-liquid extraction method has been developed as a superior method which will take the place of the amalgamation method.
According ~o this method, gallium is extracted from the aqueous sodiu}n aluminate solution containing gallium by means of an extracting agent prepared by dissolving a water-insoluble substituted quinolinol such as 7-(1-vinyl-3,3,5,5-tetramethylhexyl)-8-quinolinol in an .
organic solvent, ~nd then the extracting agent containing gallium is reverse]y extracted with an aqueous acid solution to recover gallium (Japanese Unexamined Patent Publication No. 32~11/1976). This method is practically useful as an industrial method, but it has a drawback that the substituted quinolinol in the extracting agent is susceptible to degradation. As a method for overcoming this drawback, there has been proposed a method wherein a quinolinol substituted by an alkyl group instead of the alkenyl group is used (Japanese Unexamined Patent Publication No. 52289/1978), or a me-thod wherein the operation is conducted in an inert atmosphere (Japanese Unexamined Patent Publication No. 40212/1979).
SUMMARY OF THE INVENTION
The present inventors have conducted a research to develop a method for recovering gallium in an industrially more advantageous manner than these liquid-liquid extraction methods, and as a result, have found that when the water-insoluble substituted quinolinol used in these liquid-liquid extraction methods is supported on a porous polymer, such a porous polymer exhibits excellent adsorptivity for gallium. Further, it has been unexpectedly found that the substituted quinolinol fixed in this porous polymer does not undergo degradation very much even if repeatedly used for the recovery of gallium from the aqueous sodium aluminate solution. The presént invention has been accomplished on the basis oE this
3 . ~
discovery, and presents a ~otally new rnethod which may be called an impregnated resin method.
Namely, the present invention provides a method for recovering yallium from an aqueous solution containing gallium, which comprises contacting the aqueous solution containing galliurn to a porous polymer having a water-insoluble substituted quinolinol retained therein, to let the polymer adsorb gallium, and then eluting gallium from the polymer.
DETAILED DESCRIPTION OF THE INVENTION
Now, the present invention will be described in detail with refexence to the preferred embodiments.
The present invention i5 concerned with a method for separating gallium in an aqueous solution by the adsorption with a solid adsorbing agent. The present invention is particularly useful for the recovery of gallium from a strongly basic aqueous solution, usually a strongly basic aqueous solution having a p~ of at least 10. ~ typical representative of such a strongly basic aqueous sclution containing gallium is an aqueous sodium aluminate solution formed by a Bayer process. As is well known, in the Bayer process, bauxite is treated with an aqueous sodium hydroxide solution to form an aqueous sodium aluminate solution. This aqueous sodium aluminate solution is then subjected to hydrolysis, whereby a part thereof is converted to aluminum hydroxide and sodium hydroxide. The formed aluminum hydroxide is separated, -a~ --and the remaining aqueous sodium aluMinate sollltion containing sodium hydroxide i6 adjusted ~or its concentra-tion and used ayain for the treatment of bauxite. The aqueous sodium aluminate solution after the separation of aluminum hydroxide is cornposed, for instance, of from 150 to 200 g/liter of Na2O~ from 70 to lO0 g/liter of A12O3 and about 200 mg/li-ter of gallium.
The present invention can be advantageously applied for the recovery of gallium from such an aqueous sodium lO aluminate solution.
In the present invention, various types of conventional polymers may be used as the porous polymer useful as the carrier for the substituted ~uinolinol. It is usual to employ a porous polymer having a pore volume 15 of from 0.1 to 2 ml/g, preferably from 0.3 to 1.2 ml/g as measured by mercury injection method, and an internal surface area of at least 10 m /g, preferably from 50 to 800 m2/g as measured by BET method. Such porous polymers may be produced by various methods. However, they are ~ usually prepared by the copolymerization of a monovinyl compound with a polyvinyl compound, or polyvinyl compounds with one another, or by the homopolymerization of a polyvinyl compound. ~s such vinyl compounds, there may be mentioned hydrocarbons such as styrene, methylstyrene, vinylnaphthalene, butadiene or piperylene;
styrene derivatlves such as chlorostyrene, nitrostyrene or aminostyrene; acrylonitrile derivatives such as~-, - s acrylonitrile, methacrylonitrile or ~-acetoxy-acrylonitrile; acr~lic acid, methac~ylic acid and esters thereof; divinyl benzene, divinyl toLuene, divinyl xylene, divinyl naphthalene, divinyl ethylbenzene, 5 divinyl sulfone, divinyl ketone, divinyl furan, divinyl pyridine, diallyl phthalate, diallyl succinate, ethylene glycol dimethacrylate, diallyl amine, and N,N'-ethylene bisacrylamide. As a method for producing porous polymers from these vinyl compounds, it is usual to employ a conventional precipitation solvent method or a linear polymer co-existence method. In the precipitation solvent method, the monomer is dissolved in a solvent which is capable of dissolving the monomer, but incapable of dissolving the homopolymer, and then subjected to suspension polymerization in the presence of a suitable polymerization initiator, to obtain a spherical polymer having a diameter of from 0.1 to l mm. In the linear polymer co-existence method, the monomer and the linear polymer such as polystyrene are dissolved in a suitable solvent, and likewise subjected to suspension polymerization, and the linear polymer is extracted and removed from the formed polymer with a suitable solvent.
The porous polymer to be used in the present invention preferably has a polarity to some extent.
Accordingly, preferred is a porous polymer composed essentially of acrylonitrile or its derivative; acrylic acid, methacrylic acid or an ester thereo~; divinyl-sulfone, divinyl ketone, divinyl furan, diallyl 3~
phthalate, diallyl succinate, or ethylene glycol dimethacrylate. Particularly preferred is a porous polymer composed essentially of an ester such as an acrylate, a me-thacrylate, diallyl phthalate, diallyl succinate, or ethylene glycol diacrylate or dimethacrylate. As a commercial product of such an ester-type porous polymer, there may be mentioned HP-2MG
from Mitsubishi Chemical Industries, Ltd., or XAD-7 or ~AD-8 from Rohm and Haas Co.
In the present invention, a water-insoluble substituted quinolinol is supported on the above-mentioned porous polymer, and used for the separation o~
gallium. Like in the case of the liquid-liquid extraction, in the present invention, gallium is believed lS to form a complex with the substituted quinolinol, which is then adsorbed on the porous polymer. Accordingly, as the water-insoluble substituted quinolinol, those represented by the following general formula may be employed as in the case of the conventional liquid-liquid extraction method.
R R
R ~
OH
wherein R is a hydrocarbon group or a hydrogen atom.
It is preferred to employ a 7-substituted-8-quinolinol having a substituted or unsubstituted hydrocarbon group at the 7-position. As the hydrocarbon group, those haviny a carbon number of from 5 to 20, ~ ~3~ 3' particularly from 8 to 20, are preferred. E'or instance, there may be mentioned a 1,~,~,5-te~ramethylheptyl group, a 1,4,~,6,6-pentamethyl-1-heptenyl group or a l-vinyl-3,3,5,5-tetramethylhexyl group.
In order to support the above-men-tioned substituted quinolinol on the porous polymer, the substituted quinolinol is dissolved in a suitable solvent, and the porous polymer is immersed and impregnated therein.
As mentioned above, the adsorptivity of the porous 10 polymer for gallium is dependent on the subst~tuted ~uninolinol supported or retained in -the polymer.
Therefore, the greater the amount of the quinolinol retained in the porous polymer, the better.
;; A great amount of the substituted quinolinol may be -~ 15 retained by a method wherein the porous polymer is put in a solution of the substituted quinolinol, and then the solvent is removed by evaporation. According to this method, it i5 possible to retain from 0.1 to 0.6 g of the substituted quinolinol per 1 g of the polymer when the~
20 polymer is a porous polymer having a pore volume of from 0.3 to 1.2 ml/g~
The above method represents a typical method for retaining the substituted quinolinol in the porous ~` polymer according to the present invention. However, in 25 the present invention, the manner of retaining the quinolinol is not restricted to such a typical method, but generally covers such a manner tha-t the substituted quinolinol is held in the porous polymer by a physical or ,~ , i3.~.
chemical affinity other than reactions, and is not substantially eluted ~rom the polymer by the operation of the adsorption or elution of gallium, or any other operation according to the present invention, and at least no substantial elution of the substituted quinolinol is observed by the washing with water.
According to the present invention, by means of the porous polymer having the substituted quinolinoL retained therein, thus prepared, gallium is adsorbed from the aqueous solution containing gallium. The adsorption operation may be carried out in a agitation tank system.
However, it is advantageous to conduct the adsorption in a column system.
The higher the operation temperature, the greater the adsorption speed. Therefore, the adsorption operation is usually conducted at a temperature of from 40 to 80 C.
Gallium adsorbed on the porous polymer is then eluted - with an acidic eluting solution to recover gallium. As the eluting solution, sulfuric acid, nitric acid, hydrochloric acid or the like is usually employed.
Sulfuric acid or nitric acid is employed at a concentration of at least 0.5 mol/liter, preferably at least 1 mol/liter. In the case of hydrochloric acid, if the concentration exceeds about 5 mol/liter, gallium is likely to form a chlorocomplex ion ([GaCl4] ), which will then bond, by ion exchange, to the nitrogen atom of the substituted quinolinol turned into a pyridinium ion by the presence of hydrochloric acid, whereby gallium is ;3., g _ hardly eluted. Therefore, the concentration oE
hydrochloric acid should be at most 5 mol/liter.
Usually, the concentration of hydrochloric acid is selected within a range of ~rom 0.1 to 5 mol/liter, particularly from 0.5 to 4 mol/liter.
In the case where the recovery of gallium in the sodium aluminate formed by a Bayer process is conducted according to the method of the present inventi.on, aluminum as well as gallium is adsorbed on the porous 10 polymer, and in the above-mentioned eluting method, gallium and aluminum are eluted simultaneously. To avoid the simultaneous elution~ firstly the porous polymer is ` treated with from 0.01 to 0.1 mol/liter of sul~uric acid or nitric acid to elute aluminum, and then treated with 15 at least 0.5 mol/liter of sulfuric acid or nitric acid to : elute gallium. In the case where hydrochloric acid is used as the elut.ing agent, firstly the porous polymer is , treated with hydrochloric acid having a concentration exceeding S mol/liter to elute aluminum, and then treated 20 with hydrochloric acid having a concentration of from 0.1 to 5 mol/liter to elute gallium. Of these two-step elution methods, the former is a method in which the difference in the stability o the respective complexes of aluminum and gallium is utilized by controlling the 25 acid concentration, whereas the latter is a method wherein the chlorocomplex ion-forming ability of gallium is utilized. By either method, aluminum and gallium-can be substantially completely separated and recovered from the porous polymer. Further, in the method wherein the chlorocomplex ion-forminy ability is utilized, it is also possible to use a highly concentrated aqueous alkaline solution instead of hydrochloric acid having a 5 concentration of from 0.1 to 5 mol/liter, whereby gallium is eluted by ion exchange.
According to the present invention, the recovery of gallium from the gallium-containing aqueous solution is conducted as described above, and accordingly, the operation is simple and the loss of the water-insoluble substituted quinolinol into the aqueous phase is small as compared with the conventional liquid-liquid extraction method. Further, the present invention has a feature that the degradation of the substituted quinolinol is remarkably reduced. The reason for this is not clearly understood. However, this is believed somehow related to the fact that substituted quinolinol is fixed in the porous polymer.
Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted to these specific Examples.
E~AMPLE l A solution obtained by dissolving 2.25 g of Kelex lO0 [effective component: 7~ vinyl-3,3,5,5-tetramethyl-a 1`~ e~k hexyl)-8-quinolinol]~of Messrs. AshLand Chemical Co. in lO ml of acetone, was added to 15 g of Amberlite XAD-7 ~a polymer of ethylene glycol dimethacrylate, particlé size:
~J~ S
- 11 ~6/ oe fr~c/~ ~ ~ f 0.5 mm) i.e. a synthetic adsorbe]. manufactured by~Rohm and ~aas Co. Then, whlLe stirriny the mixture, acetone was evaporated over a period of 2 hours. Then, the dried product was washed with a 3N aqueous sodium hydroYide solution and 6N hydrochloric acid, and then washed with water, and the water around XAD-7 was removed. 5 g of such XAD-7 having the substituted quinolinol retained therein, was packed in a column having inner diameter o~
18 mm ~the packing height: about 30 mm). After 3N sodium hydroxide was passed through the column, 10 ml of an aqueous sodium aluminate solution of 50C prepared in the after-mentioned manner was passed therethrough at a flow rate of 1 ml/min.
Preparation of the aqueous sodium aluminate solution To a 3N aqueous sodium hydroxide solution, aluminum hydroxide and metal galliurn were dissolved to have the respective concentrations of Al = 0.2 mol/liter and Ga = 2.46 x 10 3 mol/liter, to obtain an aqueous sodium aluminate solution containing gallium.
Then, a 3N aqueous sodium hydroxide solution and water were successively passed through the column for washing, and then gallium was eluted b-y passing 20 ml of lN hydrochloric acid at a :Elow rate of 1 ml/min.
The gallium and aluminum concentrations in the aqueous sodium aluminate solution after the column treatment and in the eluting solution, were quantitatively analyzed by atomic-absorption spectro-photometry, whereby the adsorption rate of gallium was 100~, and the elution rate was 97.5%, ~7hereas the adsorp-tion rate of aluminum was 15-~, and the elution rate was 97%.
By using the above-mentioned column and aqueous sodium aluminate solution, the adsorption-elution operation was repeated 9 times under the same conditions, whereby no substatial change was obser~ed each time in the adsorption rates and elution rates of gallium and aluminum. Further, no elution of Kelex retained in the polymer was visually observed during these operations, and further no change in the outer appearance of the polymer was observed between the initial and final stages, and no color change was observed.
The adsorption-elution operation was conducted in the same manner as in Example 1 except that 4N sulfuric acid was used instead of hydrochloric acid in Example 1, whereby the adsorption rate of gallium was 100% and the elution rate was 99%, whereas the adsorption rate of aluminum was 14% and the elution rate was 98%.
100 ml of a kerosine solution containing 8~ of Relex 100 and 100 ml of the same aqueous sodium alumlnate solution as used in Example 1, were mixed and stirred at ` 25 50C for 2 hours, and then the mixture was permitted to ` separate in-to an organic layer and an aqueous layer.
To the organic layer, 100 ml-of lN hydrochloric- acid was mixed, and the mixture was stirred at 50C for 2 hours, and then perrnitted to separate into an organic layer and an aqueous layer. The gal:Liurn concentration in this aqueous layer was quantitatLvely analyzed, whereby the extraction rate of gallium wa.s 80%.
By using the same extracting agent, the above-mentioned extraction-reverse extraction was repeated, whereby the organic layer was gradually colored red ~rom the fifth operation.
The substituted quinolinol was retained in the same manner as in Example 1 except that HP-2MG (divinyl benzene-type polymer) i.e. a synthetic adsorber manufactured by Mitsubishi Chemical Industries, Ltd. was used instead of XAD-7 in Example 1. HP-2MG having the substituted quinolinol retained therein, thus prepared, was packed in a column having an inner diameter of 9 mm to have a packing height of about 150 mm.
By using thls column, the adsorption-elution operation was repeated 5 times in the same manner as in Example 1 except that the aluminum hydroxide and metal gallium concentrations in the aqueous sodium aluminate solution containing gallium were adjusted to be Al = 1.4 mol/liter and Ga - 2.4 x 10 3 mol/liter.
To examine -the effects of the repetition, the gallium concentration in the aqueous sodium aluminate solution and the gallium and aluminum concentrations in the eluting solution after the column treatment in the third operation and thereafter, were quantitatively analyzed by atomic-absorption spectrophotometry, whereby the adsorption rate of gallium was at least 90~ in every operation, and other results were as shown below.
OperationRecover~ rate (~)*
cycle Ga Al 3 94,6 0~21
discovery, and presents a ~otally new rnethod which may be called an impregnated resin method.
Namely, the present invention provides a method for recovering yallium from an aqueous solution containing gallium, which comprises contacting the aqueous solution containing galliurn to a porous polymer having a water-insoluble substituted quinolinol retained therein, to let the polymer adsorb gallium, and then eluting gallium from the polymer.
DETAILED DESCRIPTION OF THE INVENTION
Now, the present invention will be described in detail with refexence to the preferred embodiments.
The present invention i5 concerned with a method for separating gallium in an aqueous solution by the adsorption with a solid adsorbing agent. The present invention is particularly useful for the recovery of gallium from a strongly basic aqueous solution, usually a strongly basic aqueous solution having a p~ of at least 10. ~ typical representative of such a strongly basic aqueous sclution containing gallium is an aqueous sodium aluminate solution formed by a Bayer process. As is well known, in the Bayer process, bauxite is treated with an aqueous sodium hydroxide solution to form an aqueous sodium aluminate solution. This aqueous sodium aluminate solution is then subjected to hydrolysis, whereby a part thereof is converted to aluminum hydroxide and sodium hydroxide. The formed aluminum hydroxide is separated, -a~ --and the remaining aqueous sodium aluMinate sollltion containing sodium hydroxide i6 adjusted ~or its concentra-tion and used ayain for the treatment of bauxite. The aqueous sodium aluminate solution after the separation of aluminum hydroxide is cornposed, for instance, of from 150 to 200 g/liter of Na2O~ from 70 to lO0 g/liter of A12O3 and about 200 mg/li-ter of gallium.
The present invention can be advantageously applied for the recovery of gallium from such an aqueous sodium lO aluminate solution.
In the present invention, various types of conventional polymers may be used as the porous polymer useful as the carrier for the substituted ~uinolinol. It is usual to employ a porous polymer having a pore volume 15 of from 0.1 to 2 ml/g, preferably from 0.3 to 1.2 ml/g as measured by mercury injection method, and an internal surface area of at least 10 m /g, preferably from 50 to 800 m2/g as measured by BET method. Such porous polymers may be produced by various methods. However, they are ~ usually prepared by the copolymerization of a monovinyl compound with a polyvinyl compound, or polyvinyl compounds with one another, or by the homopolymerization of a polyvinyl compound. ~s such vinyl compounds, there may be mentioned hydrocarbons such as styrene, methylstyrene, vinylnaphthalene, butadiene or piperylene;
styrene derivatlves such as chlorostyrene, nitrostyrene or aminostyrene; acrylonitrile derivatives such as~-, - s acrylonitrile, methacrylonitrile or ~-acetoxy-acrylonitrile; acr~lic acid, methac~ylic acid and esters thereof; divinyl benzene, divinyl toLuene, divinyl xylene, divinyl naphthalene, divinyl ethylbenzene, 5 divinyl sulfone, divinyl ketone, divinyl furan, divinyl pyridine, diallyl phthalate, diallyl succinate, ethylene glycol dimethacrylate, diallyl amine, and N,N'-ethylene bisacrylamide. As a method for producing porous polymers from these vinyl compounds, it is usual to employ a conventional precipitation solvent method or a linear polymer co-existence method. In the precipitation solvent method, the monomer is dissolved in a solvent which is capable of dissolving the monomer, but incapable of dissolving the homopolymer, and then subjected to suspension polymerization in the presence of a suitable polymerization initiator, to obtain a spherical polymer having a diameter of from 0.1 to l mm. In the linear polymer co-existence method, the monomer and the linear polymer such as polystyrene are dissolved in a suitable solvent, and likewise subjected to suspension polymerization, and the linear polymer is extracted and removed from the formed polymer with a suitable solvent.
The porous polymer to be used in the present invention preferably has a polarity to some extent.
Accordingly, preferred is a porous polymer composed essentially of acrylonitrile or its derivative; acrylic acid, methacrylic acid or an ester thereo~; divinyl-sulfone, divinyl ketone, divinyl furan, diallyl 3~
phthalate, diallyl succinate, or ethylene glycol dimethacrylate. Particularly preferred is a porous polymer composed essentially of an ester such as an acrylate, a me-thacrylate, diallyl phthalate, diallyl succinate, or ethylene glycol diacrylate or dimethacrylate. As a commercial product of such an ester-type porous polymer, there may be mentioned HP-2MG
from Mitsubishi Chemical Industries, Ltd., or XAD-7 or ~AD-8 from Rohm and Haas Co.
In the present invention, a water-insoluble substituted quinolinol is supported on the above-mentioned porous polymer, and used for the separation o~
gallium. Like in the case of the liquid-liquid extraction, in the present invention, gallium is believed lS to form a complex with the substituted quinolinol, which is then adsorbed on the porous polymer. Accordingly, as the water-insoluble substituted quinolinol, those represented by the following general formula may be employed as in the case of the conventional liquid-liquid extraction method.
R R
R ~
OH
wherein R is a hydrocarbon group or a hydrogen atom.
It is preferred to employ a 7-substituted-8-quinolinol having a substituted or unsubstituted hydrocarbon group at the 7-position. As the hydrocarbon group, those haviny a carbon number of from 5 to 20, ~ ~3~ 3' particularly from 8 to 20, are preferred. E'or instance, there may be mentioned a 1,~,~,5-te~ramethylheptyl group, a 1,4,~,6,6-pentamethyl-1-heptenyl group or a l-vinyl-3,3,5,5-tetramethylhexyl group.
In order to support the above-men-tioned substituted quinolinol on the porous polymer, the substituted quinolinol is dissolved in a suitable solvent, and the porous polymer is immersed and impregnated therein.
As mentioned above, the adsorptivity of the porous 10 polymer for gallium is dependent on the subst~tuted ~uninolinol supported or retained in -the polymer.
Therefore, the greater the amount of the quinolinol retained in the porous polymer, the better.
;; A great amount of the substituted quinolinol may be -~ 15 retained by a method wherein the porous polymer is put in a solution of the substituted quinolinol, and then the solvent is removed by evaporation. According to this method, it i5 possible to retain from 0.1 to 0.6 g of the substituted quinolinol per 1 g of the polymer when the~
20 polymer is a porous polymer having a pore volume of from 0.3 to 1.2 ml/g~
The above method represents a typical method for retaining the substituted quinolinol in the porous ~` polymer according to the present invention. However, in 25 the present invention, the manner of retaining the quinolinol is not restricted to such a typical method, but generally covers such a manner tha-t the substituted quinolinol is held in the porous polymer by a physical or ,~ , i3.~.
chemical affinity other than reactions, and is not substantially eluted ~rom the polymer by the operation of the adsorption or elution of gallium, or any other operation according to the present invention, and at least no substantial elution of the substituted quinolinol is observed by the washing with water.
According to the present invention, by means of the porous polymer having the substituted quinolinoL retained therein, thus prepared, gallium is adsorbed from the aqueous solution containing gallium. The adsorption operation may be carried out in a agitation tank system.
However, it is advantageous to conduct the adsorption in a column system.
The higher the operation temperature, the greater the adsorption speed. Therefore, the adsorption operation is usually conducted at a temperature of from 40 to 80 C.
Gallium adsorbed on the porous polymer is then eluted - with an acidic eluting solution to recover gallium. As the eluting solution, sulfuric acid, nitric acid, hydrochloric acid or the like is usually employed.
Sulfuric acid or nitric acid is employed at a concentration of at least 0.5 mol/liter, preferably at least 1 mol/liter. In the case of hydrochloric acid, if the concentration exceeds about 5 mol/liter, gallium is likely to form a chlorocomplex ion ([GaCl4] ), which will then bond, by ion exchange, to the nitrogen atom of the substituted quinolinol turned into a pyridinium ion by the presence of hydrochloric acid, whereby gallium is ;3., g _ hardly eluted. Therefore, the concentration oE
hydrochloric acid should be at most 5 mol/liter.
Usually, the concentration of hydrochloric acid is selected within a range of ~rom 0.1 to 5 mol/liter, particularly from 0.5 to 4 mol/liter.
In the case where the recovery of gallium in the sodium aluminate formed by a Bayer process is conducted according to the method of the present inventi.on, aluminum as well as gallium is adsorbed on the porous 10 polymer, and in the above-mentioned eluting method, gallium and aluminum are eluted simultaneously. To avoid the simultaneous elution~ firstly the porous polymer is ` treated with from 0.01 to 0.1 mol/liter of sul~uric acid or nitric acid to elute aluminum, and then treated with 15 at least 0.5 mol/liter of sulfuric acid or nitric acid to : elute gallium. In the case where hydrochloric acid is used as the elut.ing agent, firstly the porous polymer is , treated with hydrochloric acid having a concentration exceeding S mol/liter to elute aluminum, and then treated 20 with hydrochloric acid having a concentration of from 0.1 to 5 mol/liter to elute gallium. Of these two-step elution methods, the former is a method in which the difference in the stability o the respective complexes of aluminum and gallium is utilized by controlling the 25 acid concentration, whereas the latter is a method wherein the chlorocomplex ion-forming ability of gallium is utilized. By either method, aluminum and gallium-can be substantially completely separated and recovered from the porous polymer. Further, in the method wherein the chlorocomplex ion-forminy ability is utilized, it is also possible to use a highly concentrated aqueous alkaline solution instead of hydrochloric acid having a 5 concentration of from 0.1 to 5 mol/liter, whereby gallium is eluted by ion exchange.
According to the present invention, the recovery of gallium from the gallium-containing aqueous solution is conducted as described above, and accordingly, the operation is simple and the loss of the water-insoluble substituted quinolinol into the aqueous phase is small as compared with the conventional liquid-liquid extraction method. Further, the present invention has a feature that the degradation of the substituted quinolinol is remarkably reduced. The reason for this is not clearly understood. However, this is believed somehow related to the fact that substituted quinolinol is fixed in the porous polymer.
Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted to these specific Examples.
E~AMPLE l A solution obtained by dissolving 2.25 g of Kelex lO0 [effective component: 7~ vinyl-3,3,5,5-tetramethyl-a 1`~ e~k hexyl)-8-quinolinol]~of Messrs. AshLand Chemical Co. in lO ml of acetone, was added to 15 g of Amberlite XAD-7 ~a polymer of ethylene glycol dimethacrylate, particlé size:
~J~ S
- 11 ~6/ oe fr~c/~ ~ ~ f 0.5 mm) i.e. a synthetic adsorbe]. manufactured by~Rohm and ~aas Co. Then, whlLe stirriny the mixture, acetone was evaporated over a period of 2 hours. Then, the dried product was washed with a 3N aqueous sodium hydroYide solution and 6N hydrochloric acid, and then washed with water, and the water around XAD-7 was removed. 5 g of such XAD-7 having the substituted quinolinol retained therein, was packed in a column having inner diameter o~
18 mm ~the packing height: about 30 mm). After 3N sodium hydroxide was passed through the column, 10 ml of an aqueous sodium aluminate solution of 50C prepared in the after-mentioned manner was passed therethrough at a flow rate of 1 ml/min.
Preparation of the aqueous sodium aluminate solution To a 3N aqueous sodium hydroxide solution, aluminum hydroxide and metal galliurn were dissolved to have the respective concentrations of Al = 0.2 mol/liter and Ga = 2.46 x 10 3 mol/liter, to obtain an aqueous sodium aluminate solution containing gallium.
Then, a 3N aqueous sodium hydroxide solution and water were successively passed through the column for washing, and then gallium was eluted b-y passing 20 ml of lN hydrochloric acid at a :Elow rate of 1 ml/min.
The gallium and aluminum concentrations in the aqueous sodium aluminate solution after the column treatment and in the eluting solution, were quantitatively analyzed by atomic-absorption spectro-photometry, whereby the adsorption rate of gallium was 100~, and the elution rate was 97.5%, ~7hereas the adsorp-tion rate of aluminum was 15-~, and the elution rate was 97%.
By using the above-mentioned column and aqueous sodium aluminate solution, the adsorption-elution operation was repeated 9 times under the same conditions, whereby no substatial change was obser~ed each time in the adsorption rates and elution rates of gallium and aluminum. Further, no elution of Kelex retained in the polymer was visually observed during these operations, and further no change in the outer appearance of the polymer was observed between the initial and final stages, and no color change was observed.
The adsorption-elution operation was conducted in the same manner as in Example 1 except that 4N sulfuric acid was used instead of hydrochloric acid in Example 1, whereby the adsorption rate of gallium was 100% and the elution rate was 99%, whereas the adsorption rate of aluminum was 14% and the elution rate was 98%.
100 ml of a kerosine solution containing 8~ of Relex 100 and 100 ml of the same aqueous sodium alumlnate solution as used in Example 1, were mixed and stirred at ` 25 50C for 2 hours, and then the mixture was permitted to ` separate in-to an organic layer and an aqueous layer.
To the organic layer, 100 ml-of lN hydrochloric- acid was mixed, and the mixture was stirred at 50C for 2 hours, and then perrnitted to separate into an organic layer and an aqueous layer. The gal:Liurn concentration in this aqueous layer was quantitatLvely analyzed, whereby the extraction rate of gallium wa.s 80%.
By using the same extracting agent, the above-mentioned extraction-reverse extraction was repeated, whereby the organic layer was gradually colored red ~rom the fifth operation.
The substituted quinolinol was retained in the same manner as in Example 1 except that HP-2MG (divinyl benzene-type polymer) i.e. a synthetic adsorber manufactured by Mitsubishi Chemical Industries, Ltd. was used instead of XAD-7 in Example 1. HP-2MG having the substituted quinolinol retained therein, thus prepared, was packed in a column having an inner diameter of 9 mm to have a packing height of about 150 mm.
By using thls column, the adsorption-elution operation was repeated 5 times in the same manner as in Example 1 except that the aluminum hydroxide and metal gallium concentrations in the aqueous sodium aluminate solution containing gallium were adjusted to be Al = 1.4 mol/liter and Ga - 2.4 x 10 3 mol/liter.
To examine -the effects of the repetition, the gallium concentration in the aqueous sodium aluminate solution and the gallium and aluminum concentrations in the eluting solution after the column treatment in the third operation and thereafter, were quantitatively analyzed by atomic-absorption spectrophotometry, whereby the adsorption rate of gallium was at least 90~ in every operation, and other results were as shown below.
OperationRecover~ rate (~)*
cycle Ga Al 3 94,6 0~21
4 96.3 0.24 97.1 0.24 * The recovery rate is a rate relative to the gallium or aluminum in the aqueous sodium aluminate solution containing gallium.
No elution of Kelex retained in the polymer was ; visually observed during the above operations, and no substantial change in the outer appearance of the polymer was observed between the initial and final stages of the operations.
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No elution of Kelex retained in the polymer was ; visually observed during the above operations, and no substantial change in the outer appearance of the polymer was observed between the initial and final stages of the operations.
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Claims (16)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for recovering gallium from an aqueous solution containing gallium, which comprises contacting the aqueous solution containing gallium to a porous polymer having a water-insoluble substituted quinolinol retained therein, to let the polymer adsorb gallium, and then eluting gallium from the polymer.
2. The method according to Claim 1, wherein the aqueous solution containing gallium is an aqueous sodium aluminate solution formed by a Bayer process.
3. The method according to Claim 1, wherein the water-insoluble substituted quinolinol is a 7-substituted-8-quinolinol having a C5-C20 hydrocarbon group at the 7-position.
4. The method according to Claim 1, wherein the water-insoluble substituted quinolinol is 7-(1-vinyl-3,3,5,5-tetramethylhexyl)-8-quinolinol.
5. The method according to Claim 1, wherein the porous polymer has a pore volume of from 0.3 to 1.2 ml/g.
6. The method according to Claim 5, wherein the porous polymer is composed essentially of an acrylate, a methacrylate, diallyl phthalate, diallyl succinate, ethylene glycol diacrylate and/or ethylene glycol dimethacrylate.
7. The method according to Claim 1, wherein the water-insoluble substituted quinolinol is retained in the porous polymer by mixing the water-insoluble substituted quinolinol solution with the porous polymer, and then ?vaporating and removing the solvent from the mixture.
8. A process for recovering gallium from an aqueous solution containing gallium, which comprises contacting an aqueous sodium aluminate solution containing gallium formed by a Bayer proce.ss, to a porous polymer having a water-insoluble substituted quinolinol retained therein, to let the polymer adsorb gallium, and then eluting aluminum and gallium from the polymer.
9. The method according to Claim 8, wherein the gallium-adsorbed porous polyrner is contacted with sulfuric acid or nitric acid having a concentration of from 0.01 to 0.1 mol/liter to elute aluminum, and then the polymer is contacted with sulfuric acid or nitric acid having a concentration of at least 0.5 mol/liter to elute gallium.
10. The method according to Claim 8, wherein the gallium-adsorbed porous polymer is contacted with hydrochloric acid having a concentration of more than 5 mol/liter to elute aluminum, and then the polymer is contacted with hydrochloric acid having a concentration of from 0.1 to 5 mol/liter to elute gallium.
11. A method for recovering gallium selectively from an aqueous basic solution containing gallium, which comprises dis-solving 7-substituted-8- quinolinol havlng a C5-C20 hydrocarbon group at the 7-position in a solvent, mixing the resulting solu-tion with a porous polymer having a pore volume of from 0.3 to 1.2 ml/g, letting the solvent evaporate to obtain a porous poly-mer retaining substantially only the substituted quinolinol, filling a column with the polymer, passing the aqueous basic solution through the column to absorb gallium in the polymer and passing an aqueous acid solution through the column to elute gal-lium.
12. The method according to claim 11, wherein the aque-ous solution containing gallium is an aqueous sodium aluminate solution formed by a Bayer process.
13. The method according to claim 11, wherein the water insoluble substituted quinolinol is 7-(1-vinyl-3,3,5,5-tetra-methylhexyl)-8-quinolinol.
14. The method of claim 11, wherein the porous polymer is composed essentially of an acrylate, a methacrylate, diallyl phthalate, diallyl succlnate, ethylene glycol diacrylate and/or ethylene glycol dimethacrylate.
15. The method according to claim 11, wherein the gal-lium adsorbed porous polymer is contacted wlth sulfuric acid or nitric acid havlng a concentratlon of from 0.01 to 0.1 mol/liter to elute aluminum, and then the polymer is contacted with sulfu-ric acid or nitric acid having a concentration of at least 0.5 mol/liter to elute gallium.
16. The method according to claim 11, wherein the gal-lium adsorbed porous polymer is contacted with hydrochloric acid having a concentration of more than 5 mol/liter to elute alu-minum, and then the polymer is contacted with hydrochloric acid having a concentration of from 0.1 to 5 mol/liter to elute gal-lium.
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Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000486230A CA1262635A (en) | 1985-07-03 | 1985-07-03 | Method for recovering gallium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000486230A CA1262635A (en) | 1985-07-03 | 1985-07-03 | Method for recovering gallium |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1262635A true CA1262635A (en) | 1989-11-07 |
Family
ID=4130917
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000486230A Expired CA1262635A (en) | 1985-07-03 | 1985-07-03 | Method for recovering gallium |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1262635A (en) |
-
1985
- 1985-07-03 CA CA000486230A patent/CA1262635A/en not_active Expired
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