CA1157278A - Solvent extraction process for the recovery of uranium - Google Patents
Solvent extraction process for the recovery of uraniumInfo
- Publication number
- CA1157278A CA1157278A CA000379569A CA379569A CA1157278A CA 1157278 A CA1157278 A CA 1157278A CA 000379569 A CA000379569 A CA 000379569A CA 379569 A CA379569 A CA 379569A CA 1157278 A CA1157278 A CA 1157278A
- Authority
- CA
- Canada
- Prior art keywords
- uranium
- aliphatic amine
- diluent
- oxide
- bearing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B60/00—Obtaining metals of atomic number 87 or higher, i.e. radioactive metals
- C22B60/02—Obtaining thorium, uranium, or other actinides
- C22B60/0204—Obtaining thorium, uranium, or other actinides obtaining uranium
- C22B60/0217—Obtaining thorium, uranium, or other actinides obtaining uranium by wet processes
- C22B60/0252—Obtaining thorium, uranium, or other actinides obtaining uranium by wet processes treatment or purification of solutions or of liquors or of slurries
- C22B60/026—Obtaining thorium, uranium, or other actinides obtaining uranium by wet processes treatment or purification of solutions or of liquors or of slurries liquid-liquid extraction with or without dissolution in organic solvents
Abstract
28,222 TITLE: SOLVENT EXTRACTION PROCESS FOR THE RECOVERY
OF URANIUM
ABSTRACT OF THE DISCLOSURE
An extractant comprising a mixture of an aliphatic amine, a trialkylphosphine oxide and a water-immiscible, hy-drocarbon diluent has been found to achieve substantially higher degrees of uranium loading into the extraction solvent when extracting a uranium-bearing, sulfate-containing acidic leach solution with a free sulfuric acid content of less than 20.0 grams per liter.
OF URANIUM
ABSTRACT OF THE DISCLOSURE
An extractant comprising a mixture of an aliphatic amine, a trialkylphosphine oxide and a water-immiscible, hy-drocarbon diluent has been found to achieve substantially higher degrees of uranium loading into the extraction solvent when extracting a uranium-bearing, sulfate-containing acidic leach solution with a free sulfuric acid content of less than 20.0 grams per liter.
Description
~ ~5727~
28,2~
TITLE: SOLVENT EXTRACTION PROCESS FOR THE RECOVE~Y
OF URANIUM
BACKGROUND OF THE INVENTION
The methods used to extract uranium values from its ores vary widely, and composition of the uranium minerals is only one o~ several factors affecting the choice of milling methods.
The ore itself may vary from hard, i~neous rock to soft, we~kly-cemented sedimentary rock. The principal gangue mineral may be quartz, which is relatively inactive chemically, or there may be fairly large amounts of acid- consuming ~.in-erals, such as calcite, present. Some of the ores are highlyrefractory ancl require intensive treatment, while others li-terally fall apart while being transported from the mine to the mill.
After grinding and preconcentration, if practiced, tbe uranium values are leached from the ore with a suitable reagent, normally in mechanically agitated tanks or columns.
Ores containing limestone or sandstone, with a high percentage of calcite as the grain cementing material, are generally leached in alkaline circuits. Ores cemented with clay, silica~
or organic material are generally leached in acidic circuits.
It is the recovery of uranium from the acid leach liquors that the present invention is primarily concerned with.
Three principal extraction processes are currently in practice to this end: ion exchange, resin-in-pulp ion exchange and solvent extraction. The latter has been rapidly accepted by industry since its commercial inception in the 1950's because *
1 ~5~278 of the high recovery and purity of uranium product generated by this process.
The extractants in general use are alkylamines. The process is based on the property of these solvents, which are immiscible with water, to form complexes with uranium salts.
These complexes are soluble in an excess of 4 he solvent. 7~hen clarified pregnant leach solution is brought into contact with the organic solvent, the uranium is distributed between the aqueous and organic phases. Under proper process conditions, the uranium can be extracted almost quantitatively into the organic phase while most of the other constituents of the leach liquor remain in the aqueous phase. After mixing to ensure contactS the mixture of solutions is removed to a quiet settling tank where the lighter, but uranium-loaded organic layer rises to the surface and is decanted for stripping. After the solvent is stripped of its uranium content, it is returned to the mixers to meet incoming pregnant leach liquor. The uranium is stripped in an aqueous solution from which it is precipitated, usually as a very pure "yellow cake." These operations are normally conducted in batteries of cells in a countercurrent system.
Organophosphorus compounds reported in the art for use as solvents for extracting uranium from acid-leach liquors are di(2-ethylhexyl)phosphoric acid, (D2EHPA) and dodecylphos-phoric acid, (DDPA). These t~o solvents are reported to have about equal selectivity for uranium.
The alkylamines generally are tertiary aliphatic amines with high molecular weight, athough secondary amines may be useful. It is customary to use a high-flash-point kerosene as the carrier or diluent for the alkylamine. Long-chain alcohols can also be employed to improve the compatibility of the solvent and the carrier.
Stripping of the loaded alkylamine extractants is a relatively simple operation and a variety of stripping agents may be used. Nitrates and sulfates are satisfactory with close pH control. Soda ash and caustic soda have also been used commercially. The end product of the extraction process is a purified uranium solution that generally must be precipitated 7~78 and dewatered prior to shipment.
Currently, uranium is recovered from acidic sulfate solutions by extracting the leach liquors with a mixture of a triisooctylamine extractant and an isodecanol or tridecanol phase modifier both dissolved in a kerosene diluent. There is a need, however, for an improved process whereby the loading into the or~anic phase is increased and requiring fewer ex-tractions to provide an acceptable aqueous raf~inate, an ac-ceptable raffinate usually containing less than 10 parts per million (ppm) of U30g.
SUMMARY OF THE IN~ENTION
The present invention provides a novel solvent-extraction process for recovering uranium from a uranium-bearing, acidic, sulfate-containing leach solution. The pro-cess comprises initially adjusting the uranium-bearing leach solution to a free sulfuric acid content of less than 20 grams per liter; adding an effective amount of an extractant to form an organic and aqueous phase mixture wherein the extractant comprises an aliphatic amine or its sulfate salt, a trialkyl--phosphine oxide and a water-immiscible, hydrocarbon diluent;
agitating the leach solution so as to allow the uranium to form an organic complex; settling the two-phase mixture; and sep-arating the acidic aqueous phase from the uranium-bearing organic phase. The instant process is advantageous in that it 25 provides substantially higher uranium loading into the ex-traction solvent which, in turn, allows for the processing of leach liquors containing higher concentrations of uranium.
Furthermore, the instant process reduces t;he uranium concen-tration in the raffinate thereby providing increased overall 30 productivity since fewer extractions are required to produce an acceptable raffinate.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, the ura-nium-bearing, acidic leach solution is initially assayed to 35 determine the free sulfuric acid content. If the free sulfuric acid content îs above 20 gra~s per liter, the solution is treated with an alkalizing agent to adjust the frae suffuric acid content, preferably to about 5 to lO grams per liter.
1 ~5727~
~ Yhen the acidic leacll solution is prol1erly adjustcd, an effect:ive amount of a solvent is then addcd. Generally, the effective amount will vary depending upon the specific u-raniwn ore being treated, the concentration of ura-nium in the leacll liquor, the free sulfuric acid content of the leach liquor and the like. Ilowevel~, in most commercial applications, contacting from about 0.05 ~o 1.0 part by volume of the solvent with about 1.0 part by volume of the urani-um-bearing, acidic leach solution will be effective.
The solvent comprises a mixture of from about 1.0 to 10.0 percent, by volume, of an aliphatic amine or the sulfate salt thereof, from abo~lt 1.0 to lO.O percent, by vol~ne, of a trialkylphosphine oxide and from about 98.0 ~o SO.0 percent, by volume, of a water-immiscible, hydrocarbon diluent. The pre-ferred amounts of these components are, by volume, about 2.0 to 5.0 percent ali-phatic amine, about 2.0 to 5.0 percent trialkylphosphine oxide and 96.0 to 90.0 percent water-immiscible, hydrocarbon diluent.
Suitable aliphatic amines for use in the instant process have eight to eighteen carbon atoms per alkyl group, inclusive. More preferably, these C8 to C18 aliphatic amines are tertiary aliphatic amines. Representative aliphatic amines for use in the instant process include, but are not limited to, n-octyl-amine, 2-ethylhexylamine, n-dodecylamine, n-octadecylamine, di-n-octylamine, bis~2-ethylhexyl)amine, di-n-octadecylamine, tris(2-ethylhexyl)amine, triiso-octylamineJ and tri-n-dodecylamine. The preferred aliphatic amine being triiso-octylamine.
Suitable trialkylphosphine oxides for use in the instant process in-clude, but are not limited to, tri-n-hexylphosphine oxide, tricyclohexylphos-phine oxide, tri-n-octylphosphine oxide, triisooctylphosphine oxide and tri-n-dodecylphosphine oxide. The preferred trialkylphosphine oxide being tri-n-octylphosphine oxide.
I ~ 7 ~3 Suitable water-immi.scible, hydrocarbon diluents useful in the instant process include, but are not lim:ited to, benzene, toluene, xylene, naphtha, ker-osene and the like.
- 4a -. ~ .
.
~ ~5~278 Kerosene being the pref`erred diluent.
The solvent may be used as prepared. Preferably, it ls preconditioned by contacting it with a solution of sùlfuric acid in water to convert the amine to the sulfate salt.
In carryin~ out the process of the present inven-tion, the uranium-bearing aqueous solution is contacted ei-ther by batch, continuously co-current or continuously count-er~current, with the extraction solvent. The ratio of aqueous to organic phase should be chosen to most effectively remove the uranium. Aqueous to organic ratios of from 1:20 to 20:1 are believed to be effective, although other ratios may prove to be effective, depending upon the specific separation.
Phase contact is commonly achieved in devices called "mixer--settlers", although many other types of devices are available and suitable. In the mixer, one phase is dispersed within the other by stirring or some other appropriate form of agitation.
The extraction solvent then forms a complex with the uranlum which reporis to the organic phase of the two-phase liquid mixture. The dispersion then flows to the settler where phase disegagement occurs under quiescent conditions. Generally, extraction is carried out between 0-100C., preferably 20-_70C.
The organic phase, now loaded with uranium ex-tracted from the uranium-bearing, acidic leach solution, may be further processed by contact with an aqueous solution containing a stripping agent to remove the uranium from the organic phase back into the aqueous phase. Suitable stripping agents include, but are not limited to, sodium chloride, ammonium carbonate, sodium hydroxide, ammonium sulfate, ammo-3 nium chloride, sodium carbonate, ammonium hydrsxide, sodiumsulfate and hydrochloric acid. Preferably, sodium carbonate is employed as the stripping agent. The stripped organic phase is then separated from the uranium-loaded aqueous phase and utilized again to extract uranium from the acidic leach solution as previously described. The uranium- bearing aque-ous phase is precipitated and dewatered to obtain the purified uranium.
- J 15~278 Whereas the exact scope of the instant invention is set forth in the appended claims, the followirlg specific examples illustrate certain aspects o~ the present invention, and more particularly, point out methods of evaluating the same. However, the examples are set forth for illustration only and are not to be construed as limitations on the pres-ent invention except as set forth in the appended claims. All parts and percentages are by volume unless otherwise speci-fied.
An aqueous, uranium-bearing, acidic leach solution is prepared to provide 1.0 gram per liter of U30g, 2.5 grams per liter of free sulfuric acid and 50 grams per liter of total ~04~2,added as Na2S04.
Equal volume samples of the acidic leach solution are extracted with a solvent at different volume ratios of aqueous (A) to organic (0) phases. The solvent used to extract the uranium comprise:
Extraction Composition A:
3%, by volume, of triisooctylamine 3~, by volume, of tri-n-octylphosphine oxide 94~, by volume, of kerosene Extraction Composition B:
3%, by volume, of triisooctylamine 3%, by volume, of isodecanol 94%, by volume, of kerosene The solvents are equilibrated before being added to the acidic leach liquors by agitation for 15 minutes with an equal volume of a 5% aqueous solution Or sulfuric acid to convert the amine in the composition to its sulfate salt. The resulting solvent is used to extract the uranium leach solu-tion in the ratios shown in Table I.
The extraction isotherms for the various combina-tions of uranium-bearing, acidic leach solutions and solvents 35 are obtained by equilibrating aliquots of the aqueous and organic phase for 15 minutes on a shaker at 240C. Test results are reported in Table I below.
~ ~5~278 ~ C;~ 0~ G~ ~ a~ t` I`
O o o ~
~ O O O O O O O O
~
O
_ ,~
U~
~r ~ O
O _ Q
U~ ~ 0~ ~
~:: O C~ ~
,~ s:: I` ~ ~I co u~
O~ r~
~) O O O ~1 ~ 3 N t~
~n .
O
U~ U
~1 ~. O
~; ~ D u~
~` ~ 1` ~ ~1 0~ r~
m o ~ o O O ,, ~ U~ ~ ~ o o o ~ O
E-l H ,1 ~
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~ U U
H 1:: t` ~ 1~1 L'l --1 L'l ~`1 L-~ (l~ ~ D 00 0 t~
~) O O O .-1 ~`I t~l ~1 O I ~ u~ In ~ I ~ ~ ~ ~ ~ ~r 1 ~57278 The procedure of Example 1 is followed in every material detail except that the free sulfuric acid content of the leach solution is 5.0 grams per liter. Test results are reported in Table II.
~ ~57278 ~ co o o o a~ o o o o ,~ ~ ~ ~
~ o o o o ~ o o o m ~
~_ ,~
~ U~
c~ ~ R~
O ~ o ~1 ~ O
X ,~ ~: I` ~ ~ ~ ~ ~ o U~
11~ ~ ~r ~ co ,~ ~;r ~ oo a~
h o o ~J t~
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n r~
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U~
H ¦ ~;1 O
H ~C
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¢ ~,~ ~
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E~ ~
~1 ~ ~ _, E~ ~ ., ~C U~
~ 3~
Z; ~ r~
;~ ~ o o ,~
o ~ O ~ ~ ~ ~ ~ ~ ~D
1 ~727~
~ 10 --The procedure of Example 1 is followed in every material detail except that the free sulfuric acid content of the leach solution is 10.0 grams per liter. Test results are reported in Table III.
3o 3 ~ ~ o ~
O O o ~r) Lfl ~ 1 G
~ O O O O r~
m O O O O O O O O
o ~ ~ o UO~ _, o t~
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O ~ ~ ~ ~ ~ oo n ~ cn ~ o o o ~ ~ In ~ ~ ~`I
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E~ HO R ~ ~¢
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H O~1 ¦
Z ~ C~ 0 C~ 1-l Lrl CO
'¢ (1 ~t' Ci~ CO r~ ~ O N ~--O O o ~ ~ ~ ~ r~
I U~
~ I O
1 ~7~7~
The procedure of Example 1 is followed in every material detail except that the free ~ulfuric acid content of the leach solution is 20.0 grams per liter. Test results are reported in Table IV.
3o 1 ~57278 o o o o o o C o o o o o o o ~ o ~ .,, ol E¦ u ~ ~ ~ e o ~ o O O
a~
21~: v ~ 1 Z E ~ o o o o o o o o ,~ C
O. U1 ~ h O o ~1 ~ ~
`I "' ~ Ln o _I ~ ~ ~ ~ ~ ~o 1 157~78 The procedure of Example 1 is followed in every material detail except that the free sulfuric acid content of leach solution is 50.0 grams per liter. Test results are reported in Table V.
.
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28,2~
TITLE: SOLVENT EXTRACTION PROCESS FOR THE RECOVE~Y
OF URANIUM
BACKGROUND OF THE INVENTION
The methods used to extract uranium values from its ores vary widely, and composition of the uranium minerals is only one o~ several factors affecting the choice of milling methods.
The ore itself may vary from hard, i~neous rock to soft, we~kly-cemented sedimentary rock. The principal gangue mineral may be quartz, which is relatively inactive chemically, or there may be fairly large amounts of acid- consuming ~.in-erals, such as calcite, present. Some of the ores are highlyrefractory ancl require intensive treatment, while others li-terally fall apart while being transported from the mine to the mill.
After grinding and preconcentration, if practiced, tbe uranium values are leached from the ore with a suitable reagent, normally in mechanically agitated tanks or columns.
Ores containing limestone or sandstone, with a high percentage of calcite as the grain cementing material, are generally leached in alkaline circuits. Ores cemented with clay, silica~
or organic material are generally leached in acidic circuits.
It is the recovery of uranium from the acid leach liquors that the present invention is primarily concerned with.
Three principal extraction processes are currently in practice to this end: ion exchange, resin-in-pulp ion exchange and solvent extraction. The latter has been rapidly accepted by industry since its commercial inception in the 1950's because *
1 ~5~278 of the high recovery and purity of uranium product generated by this process.
The extractants in general use are alkylamines. The process is based on the property of these solvents, which are immiscible with water, to form complexes with uranium salts.
These complexes are soluble in an excess of 4 he solvent. 7~hen clarified pregnant leach solution is brought into contact with the organic solvent, the uranium is distributed between the aqueous and organic phases. Under proper process conditions, the uranium can be extracted almost quantitatively into the organic phase while most of the other constituents of the leach liquor remain in the aqueous phase. After mixing to ensure contactS the mixture of solutions is removed to a quiet settling tank where the lighter, but uranium-loaded organic layer rises to the surface and is decanted for stripping. After the solvent is stripped of its uranium content, it is returned to the mixers to meet incoming pregnant leach liquor. The uranium is stripped in an aqueous solution from which it is precipitated, usually as a very pure "yellow cake." These operations are normally conducted in batteries of cells in a countercurrent system.
Organophosphorus compounds reported in the art for use as solvents for extracting uranium from acid-leach liquors are di(2-ethylhexyl)phosphoric acid, (D2EHPA) and dodecylphos-phoric acid, (DDPA). These t~o solvents are reported to have about equal selectivity for uranium.
The alkylamines generally are tertiary aliphatic amines with high molecular weight, athough secondary amines may be useful. It is customary to use a high-flash-point kerosene as the carrier or diluent for the alkylamine. Long-chain alcohols can also be employed to improve the compatibility of the solvent and the carrier.
Stripping of the loaded alkylamine extractants is a relatively simple operation and a variety of stripping agents may be used. Nitrates and sulfates are satisfactory with close pH control. Soda ash and caustic soda have also been used commercially. The end product of the extraction process is a purified uranium solution that generally must be precipitated 7~78 and dewatered prior to shipment.
Currently, uranium is recovered from acidic sulfate solutions by extracting the leach liquors with a mixture of a triisooctylamine extractant and an isodecanol or tridecanol phase modifier both dissolved in a kerosene diluent. There is a need, however, for an improved process whereby the loading into the or~anic phase is increased and requiring fewer ex-tractions to provide an acceptable aqueous raf~inate, an ac-ceptable raffinate usually containing less than 10 parts per million (ppm) of U30g.
SUMMARY OF THE IN~ENTION
The present invention provides a novel solvent-extraction process for recovering uranium from a uranium-bearing, acidic, sulfate-containing leach solution. The pro-cess comprises initially adjusting the uranium-bearing leach solution to a free sulfuric acid content of less than 20 grams per liter; adding an effective amount of an extractant to form an organic and aqueous phase mixture wherein the extractant comprises an aliphatic amine or its sulfate salt, a trialkyl--phosphine oxide and a water-immiscible, hydrocarbon diluent;
agitating the leach solution so as to allow the uranium to form an organic complex; settling the two-phase mixture; and sep-arating the acidic aqueous phase from the uranium-bearing organic phase. The instant process is advantageous in that it 25 provides substantially higher uranium loading into the ex-traction solvent which, in turn, allows for the processing of leach liquors containing higher concentrations of uranium.
Furthermore, the instant process reduces t;he uranium concen-tration in the raffinate thereby providing increased overall 30 productivity since fewer extractions are required to produce an acceptable raffinate.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, the ura-nium-bearing, acidic leach solution is initially assayed to 35 determine the free sulfuric acid content. If the free sulfuric acid content îs above 20 gra~s per liter, the solution is treated with an alkalizing agent to adjust the frae suffuric acid content, preferably to about 5 to lO grams per liter.
1 ~5727~
~ Yhen the acidic leacll solution is prol1erly adjustcd, an effect:ive amount of a solvent is then addcd. Generally, the effective amount will vary depending upon the specific u-raniwn ore being treated, the concentration of ura-nium in the leacll liquor, the free sulfuric acid content of the leach liquor and the like. Ilowevel~, in most commercial applications, contacting from about 0.05 ~o 1.0 part by volume of the solvent with about 1.0 part by volume of the urani-um-bearing, acidic leach solution will be effective.
The solvent comprises a mixture of from about 1.0 to 10.0 percent, by volume, of an aliphatic amine or the sulfate salt thereof, from abo~lt 1.0 to lO.O percent, by vol~ne, of a trialkylphosphine oxide and from about 98.0 ~o SO.0 percent, by volume, of a water-immiscible, hydrocarbon diluent. The pre-ferred amounts of these components are, by volume, about 2.0 to 5.0 percent ali-phatic amine, about 2.0 to 5.0 percent trialkylphosphine oxide and 96.0 to 90.0 percent water-immiscible, hydrocarbon diluent.
Suitable aliphatic amines for use in the instant process have eight to eighteen carbon atoms per alkyl group, inclusive. More preferably, these C8 to C18 aliphatic amines are tertiary aliphatic amines. Representative aliphatic amines for use in the instant process include, but are not limited to, n-octyl-amine, 2-ethylhexylamine, n-dodecylamine, n-octadecylamine, di-n-octylamine, bis~2-ethylhexyl)amine, di-n-octadecylamine, tris(2-ethylhexyl)amine, triiso-octylamineJ and tri-n-dodecylamine. The preferred aliphatic amine being triiso-octylamine.
Suitable trialkylphosphine oxides for use in the instant process in-clude, but are not limited to, tri-n-hexylphosphine oxide, tricyclohexylphos-phine oxide, tri-n-octylphosphine oxide, triisooctylphosphine oxide and tri-n-dodecylphosphine oxide. The preferred trialkylphosphine oxide being tri-n-octylphosphine oxide.
I ~ 7 ~3 Suitable water-immi.scible, hydrocarbon diluents useful in the instant process include, but are not lim:ited to, benzene, toluene, xylene, naphtha, ker-osene and the like.
- 4a -. ~ .
.
~ ~5~278 Kerosene being the pref`erred diluent.
The solvent may be used as prepared. Preferably, it ls preconditioned by contacting it with a solution of sùlfuric acid in water to convert the amine to the sulfate salt.
In carryin~ out the process of the present inven-tion, the uranium-bearing aqueous solution is contacted ei-ther by batch, continuously co-current or continuously count-er~current, with the extraction solvent. The ratio of aqueous to organic phase should be chosen to most effectively remove the uranium. Aqueous to organic ratios of from 1:20 to 20:1 are believed to be effective, although other ratios may prove to be effective, depending upon the specific separation.
Phase contact is commonly achieved in devices called "mixer--settlers", although many other types of devices are available and suitable. In the mixer, one phase is dispersed within the other by stirring or some other appropriate form of agitation.
The extraction solvent then forms a complex with the uranlum which reporis to the organic phase of the two-phase liquid mixture. The dispersion then flows to the settler where phase disegagement occurs under quiescent conditions. Generally, extraction is carried out between 0-100C., preferably 20-_70C.
The organic phase, now loaded with uranium ex-tracted from the uranium-bearing, acidic leach solution, may be further processed by contact with an aqueous solution containing a stripping agent to remove the uranium from the organic phase back into the aqueous phase. Suitable stripping agents include, but are not limited to, sodium chloride, ammonium carbonate, sodium hydroxide, ammonium sulfate, ammo-3 nium chloride, sodium carbonate, ammonium hydrsxide, sodiumsulfate and hydrochloric acid. Preferably, sodium carbonate is employed as the stripping agent. The stripped organic phase is then separated from the uranium-loaded aqueous phase and utilized again to extract uranium from the acidic leach solution as previously described. The uranium- bearing aque-ous phase is precipitated and dewatered to obtain the purified uranium.
- J 15~278 Whereas the exact scope of the instant invention is set forth in the appended claims, the followirlg specific examples illustrate certain aspects o~ the present invention, and more particularly, point out methods of evaluating the same. However, the examples are set forth for illustration only and are not to be construed as limitations on the pres-ent invention except as set forth in the appended claims. All parts and percentages are by volume unless otherwise speci-fied.
An aqueous, uranium-bearing, acidic leach solution is prepared to provide 1.0 gram per liter of U30g, 2.5 grams per liter of free sulfuric acid and 50 grams per liter of total ~04~2,added as Na2S04.
Equal volume samples of the acidic leach solution are extracted with a solvent at different volume ratios of aqueous (A) to organic (0) phases. The solvent used to extract the uranium comprise:
Extraction Composition A:
3%, by volume, of triisooctylamine 3~, by volume, of tri-n-octylphosphine oxide 94~, by volume, of kerosene Extraction Composition B:
3%, by volume, of triisooctylamine 3%, by volume, of isodecanol 94%, by volume, of kerosene The solvents are equilibrated before being added to the acidic leach liquors by agitation for 15 minutes with an equal volume of a 5% aqueous solution Or sulfuric acid to convert the amine in the composition to its sulfate salt. The resulting solvent is used to extract the uranium leach solu-tion in the ratios shown in Table I.
The extraction isotherms for the various combina-tions of uranium-bearing, acidic leach solutions and solvents 35 are obtained by equilibrating aliquots of the aqueous and organic phase for 15 minutes on a shaker at 240C. Test results are reported in Table I below.
~ ~5~278 ~ C;~ 0~ G~ ~ a~ t` I`
O o o ~
~ O O O O O O O O
~
O
_ ,~
U~
~r ~ O
O _ Q
U~ ~ 0~ ~
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,~ s:: I` ~ ~I co u~
O~ r~
~) O O O ~1 ~ 3 N t~
~n .
O
U~ U
~1 ~. O
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m o ~ o O O ,, ~ U~ ~ ~ o o o ~ O
E-l H ,1 ~
S-l til O O O O O O o o Z Q ~ f~
H ,_1 1::
~1 ~1 C) ~ .,1 ~ :
~ U U
H 1:: t` ~ 1~1 L'l --1 L'l ~`1 L-~ (l~ ~ D 00 0 t~
~) O O O .-1 ~`I t~l ~1 O I ~ u~ In ~ I ~ ~ ~ ~ ~ ~r 1 ~57278 The procedure of Example 1 is followed in every material detail except that the free sulfuric acid content of the leach solution is 5.0 grams per liter. Test results are reported in Table II.
~ ~57278 ~ co o o o a~ o o o o ,~ ~ ~ ~
~ o o o o ~ o o o m ~
~_ ,~
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c~ ~ R~
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n r~
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U~
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E~ ~
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o ~ O ~ ~ ~ ~ ~ ~ ~D
1 ~727~
~ 10 --The procedure of Example 1 is followed in every material detail except that the free sulfuric acid content of the leach solution is 10.0 grams per liter. Test results are reported in Table III.
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The procedure of Example 1 is followed in every material detail except that the free ~ulfuric acid content of the leach solution is 20.0 grams per liter. Test results are reported in Table IV.
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a~
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`I "' ~ Ln o _I ~ ~ ~ ~ ~ ~o 1 157~78 The procedure of Example 1 is followed in every material detail except that the free sulfuric acid content of leach solution is 50.0 grams per liter. Test results are reported in Table V.
.
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2'1 r-l ~`3 ~`3 1 ~727 When the procedure of Example 2 is followed in every material detail except that for composition A there is nol~
employed 5%, by volume, of n-octylamine; 7%, by volume, of triisooctylphosphine oxide and 88%, by volume, of benzene, substantially equivalent results are obtained.
When the procedure of Example 2 is followed in every material detail except that for Composition A there is now employed 7~, by volume, of di-n-octadecylamine; 9%, by volume, of tri-n-dodecylphosphine oxide and 84~, by volume~ of tolu-ene, substantially equivalent results are obtained~
~XAMPLE 8 When the procedure of Example 2 is followed in every material detail except that for Composition A there is now employed 9%, by volume, of tris(2-ethylhexyl)amine; 2%, by volume, of tri-n-hexylphosphine oxide and 89%, by volume, of xylene; substantially equivalent results are obtained.
EX~PLE 9 When the procedure of Example 2 is followed in every material detail except that for Composition A there is now employed 2%, by volume, of tri-n-dodecylamine; 5%, by volume, of tricyclohexylphosphine oxide and 93%, by volume, of naphtha and said Composition is not contacted with sulfuric acid to convert the amine to the sulfate salt prior to extraction, substantially equivalent results are obtained.
employed 5%, by volume, of n-octylamine; 7%, by volume, of triisooctylphosphine oxide and 88%, by volume, of benzene, substantially equivalent results are obtained.
When the procedure of Example 2 is followed in every material detail except that for Composition A there is now employed 7~, by volume, of di-n-octadecylamine; 9%, by volume, of tri-n-dodecylphosphine oxide and 84~, by volume~ of tolu-ene, substantially equivalent results are obtained~
~XAMPLE 8 When the procedure of Example 2 is followed in every material detail except that for Composition A there is now employed 9%, by volume, of tris(2-ethylhexyl)amine; 2%, by volume, of tri-n-hexylphosphine oxide and 89%, by volume, of xylene; substantially equivalent results are obtained.
EX~PLE 9 When the procedure of Example 2 is followed in every material detail except that for Composition A there is now employed 2%, by volume, of tri-n-dodecylamine; 5%, by volume, of tricyclohexylphosphine oxide and 93%, by volume, of naphtha and said Composition is not contacted with sulfuric acid to convert the amine to the sulfate salt prior to extraction, substantially equivalent results are obtained.
Claims (15)
1. A process for extracting uranium from a uran-ium-bearing, sulfate-containing acidic leach solution which comprises:
(a) adjusting the uranium-bearing leach solu-tion to a free sulfuric acid content of less than 20 grams per liter;
(b) adding an effective amount of a solvent to form an organic and aqueous phase mixture wherein the solvent comprises an aliphatic amine or its sulfate salt, a trialkyl-phosphine oxide and a water-immiscible, hydrocarbon diluent;
(c) agitating the leach solution so as to allow the uranium to form an organic complex;
(d) settling the two-phase mixture; and (e) separating the acidic aqueous phase from the uranium-bearing organic phase.
(a) adjusting the uranium-bearing leach solu-tion to a free sulfuric acid content of less than 20 grams per liter;
(b) adding an effective amount of a solvent to form an organic and aqueous phase mixture wherein the solvent comprises an aliphatic amine or its sulfate salt, a trialkyl-phosphine oxide and a water-immiscible, hydrocarbon diluent;
(c) agitating the leach solution so as to allow the uranium to form an organic complex;
(d) settling the two-phase mixture; and (e) separating the acidic aqueous phase from the uranium-bearing organic phase.
2. The process of Claim 1 wherein the uranium-bearing, sulfate-containing acidic leach solution is adjusted to a free sulfuric acid content of about 5-10 grams per liter.
3. The process of Claim 1 wherein the solvent comprises, by volume, from about 1.0 to 10.0 percent of an aliphatic amine or the sulfate salt thereof, from about 1.0 to 10.0 percent of a trialkylphosphine oxide and from about 98.0 to 80.0 percent of a water-immiscible hydrocarbon diluent.
4. The process of Claim 3 wherein the solvent comprises, by volume, from about 2.0 to 5.0 percent of an aliphatic amine or the sulfate salt thereof, from about 2.0 to 5.0 percent of a trialkylphosphine oxide and from 96.0 to 90.0 percent of a water-immiscible, hydrocarbon diluent.
5. The process of Claim 3 wherein the aliphatic amine has eight to eighteen carbon atoms inclusive.
6. The process of Claim 5 wherein the aliphatic amine is a tertiary aliphatic amine.
7. The process of Claim 6 wherein the tertiary aliphatic amine is triisooctylamine.
8. The process of Claim 3 wherein the trialkyl-phosphine oxide is tri-n-octylphosphine oxide.
9. The process of Claim 3 wherein the diluent is an aromatic or aliphatic petroleum distillate or a mixture of the two.
10. The process of Claim 9 wherein the diluent is selected from the group consisting of benzene, toluene, xy-lene, naphtha and kerosene.
11. The process of Claim 10 wherein the diluent is kerosene.
12. The process of Claim 3 wherein the aliphatic amine is a tertiary aliphatic amine having eight to eighteen carbon atoms, inclusive or the sulfate salt thereof, the trialkylphosphine oxide is tri-n-octylphosphine oxide and the diluent is kerosene.
13. The process of Claim 3 or 4 wherein the alipha-tic amine is triisooctylamine or the sulfate salt thereof, the trialkylphosphine oxide is tri-n-octylphosphine oxide and the diluent is kerosene.
14. The process of Claim 1 wherein the effective amount of the solvent is from about 0.05 to 1.0 part, by volume, per 1.0 part of uranium-bearing, sulfate containing acidic leach solution.
15. The process of Claim 1 wherein the resultant uranium-bearing organic phase is thereafter stripped by an aqueous solution containing a stripping agent and separated from the resultant uranium-loaded aqueous phase for reuse as a solvent.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000379569A CA1157278A (en) | 1981-06-11 | 1981-06-11 | Solvent extraction process for the recovery of uranium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000379569A CA1157278A (en) | 1981-06-11 | 1981-06-11 | Solvent extraction process for the recovery of uranium |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1157278A true CA1157278A (en) | 1983-11-22 |
Family
ID=4120216
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000379569A Expired CA1157278A (en) | 1981-06-11 | 1981-06-11 | Solvent extraction process for the recovery of uranium |
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| Country | Link |
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| CA (1) | CA1157278A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011095679A1 (en) * | 2010-02-02 | 2011-08-11 | Outotec Oyj | Extraction process |
-
1981
- 1981-06-11 CA CA000379569A patent/CA1157278A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011095679A1 (en) * | 2010-02-02 | 2011-08-11 | Outotec Oyj | Extraction process |
| CN102741433A (en) * | 2010-02-02 | 2012-10-17 | 奥图泰有限公司 | Extraction process |
| US8926924B2 (en) | 2010-02-02 | 2015-01-06 | Outotec Oyj | Extraction process |
| EA021530B1 (en) * | 2010-02-02 | 2015-07-30 | Ототек Оюй | Extraction process |
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