GB2082154A - Extracting uranium values from aqueous phosphoric acid - Google Patents
Extracting uranium values from aqueous phosphoric acid Download PDFInfo
- Publication number
- GB2082154A GB2082154A GB8026084A GB8026084A GB2082154A GB 2082154 A GB2082154 A GB 2082154A GB 8026084 A GB8026084 A GB 8026084A GB 8026084 A GB8026084 A GB 8026084A GB 2082154 A GB2082154 A GB 2082154A
- Authority
- GB
- United Kingdom
- Prior art keywords
- phosphoric acid
- stream
- uranium
- contactor
- organic solvent
- 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.)
- Granted
Links
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 title claims abstract description 81
- 229910000147 aluminium phosphate Inorganic materials 0.000 title claims abstract description 41
- 229910052770 Uranium Inorganic materials 0.000 title claims abstract description 37
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 title claims abstract description 37
- 239000003960 organic solvent Substances 0.000 claims abstract description 24
- 239000007788 liquid Substances 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 16
- 239000002904 solvent Substances 0.000 claims description 12
- 239000003638 chemical reducing agent Substances 0.000 claims description 3
- SEGLCEQVOFDUPX-UHFFFAOYSA-N di-(2-ethylhexyl)phosphoric acid Chemical compound CCCCC(CC)COP(O)(=O)OCC(CC)CCCC SEGLCEQVOFDUPX-UHFFFAOYSA-N 0.000 claims description 3
- 239000003085 diluting agent Substances 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- ZMBHCYHQLYEYDV-UHFFFAOYSA-N trioctylphosphine oxide Chemical compound CCCCCCCCP(=O)(CCCCCCCC)CCCCCCCC ZMBHCYHQLYEYDV-UHFFFAOYSA-N 0.000 claims description 3
- 238000000605 extraction Methods 0.000 abstract description 9
- 239000012071 phase Substances 0.000 description 17
- 239000002253 acid Substances 0.000 description 8
- 239000008346 aqueous phase Substances 0.000 description 7
- 239000012074 organic phase Substances 0.000 description 7
- 239000011368 organic material Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000002367 phosphate rock Substances 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000005352 clarification Methods 0.000 description 2
- 238000004945 emulsification Methods 0.000 description 2
- 239000003337 fertilizer Substances 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 1
- 239000003350 kerosene Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000010405 reoxidation reaction Methods 0.000 description 1
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
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Manufacturing & Machinery (AREA)
- Environmental & Geological Engineering (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Extraction Or Liquid Replacement (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
In the extraction of uranium values from aqueous phosphoric acid containing those values, a stream of the phosphoric acid and a stream (6) of an organic solvent selective for uranium are passed in separate phases (28, 29) through a continuous rotary liquid/liquid contactor (5) in which the phases are gently intermingled during their passage. The uranium is then stripped from the uranium-rich organic solvent in a second contactor (9) and recycled to the first contactor.
Description
SPECIFICATION
Extraction of uranium values from aqueous phoshoric acid
This invention relates to the extraction of uranium values from aqueous phosphoric acid. Phosphoric acid is made in large quantities by the wet process from phosphate rockforthe production of phosphate fertiliser. Phosphate rock as mined usually contains uranium in minor proportions; by virtue of the quantities of phosphate rock processed, it is however a valuable source of uranium.
The extraction of uranium values from dilute phoshoric acid is already known. The phosphoric acid is contacted with an organic solvent consisting of an extractant which is selective for uranium and which is dissolved in an organic diluent. The uranium values are transferred to the solvent and are thereafter stripped from the solvent in a stripping stage, by contacting the uranium-rich solvent with a stripping agent.
In the known process, both the extraction and the stripping are performed in mixer-settlers. Raw phoshoric acid derived from many phosphate rock sources naturally contains soluble organic material which, when the phosphoric acid is fiercely agitated with the extractant in the mixers, promotes emulsification of the solvent and causes a part of the solvent to be lost in the phosphoric acid raffinate; not only does that loss represent an economic burden on the process, but, more significantly, the inclusion of appreciable amounts of the solvent in the treated phosphoric acid prevents the immediate use of the phosphoric acid forfertiliser production.Consequently, it has been necessary to treat the phosphoric acid prior to uranium extraction for removal of soluble organic material and to process the phosphoric acid after the extraction for removal of any organic solvent that may be present. The equipment necessary for those treatments adds to the complexity and expense of the process.
Furthermore, the violent agitation in the mixers of the stripping stage results in loss of the organic solvent to the stripping agent.
The present invention resides in a process for extracting uranium values from aqueous phosphoric acid using an organic solvent containing an extractant selective for uranium and is characterised in that a stream of the aqueous phosphoric acid and a stream of the organic solvent are passed in separate phases through a continuous rotary liquid/liquid contactor in which the aqueous phosphoric acid and the solvent are gently intermingled during their passage. Surprisingly the gentle intermingling of the streams in the rotary contactor does not give rise to emulsification of the organic solvent, even when soluble organic material is present in the phosphoric acid feed stream, and minimises the proportion of the organic solvent that leaves the contactor in the phosphoric acid raffinate.It then becomes unnecessary to treat the phosphoric acid feed for removal of soluble organic material or to treat the phosphoric acid raffinate for recovery of the contained organic solvent prior to passing the phosphoric acid forward forfertiliser production.
Preferably, the uranium values are stripped from the uranium-rich solvent stream from the contactor by contacting that stream with a stripping stream in a second, similar, continuous rotary contactor. The stripping stream leaving the second contactor is found to include minimal quantities of the organic solvent.
The invention will be more readily understood by way of example from the following description of a process for the extraction of uranium values from wet-process phosphoric acid, reference being made to the accompanying drawings, in which
Figure 1 is a flow diagram of part of the process, and
Figure 2 diagrammatically shows a radial section through one of the contactors.
Referring to the drawing, dilute phosphoric acid containing a minor proportion of uranium values is pumped on line 1 from the phosphoric acid plant to a holding tank 2 where oxidant entered at 3 is mixed with the acid to oxidise the uranium to the hexavelent form. Standby clarification equipment 4 is provided to remove suspended matter should insufficient clarification occur in the phosphoric acid plant. No equipment is supplied for removing soluble organic material from the phosphoric acid feed.
The clarified acid is pumped from tank 2 to a continuous rotary contactor 5 where it is contacted with a countercurrent stream of an organic solvent fed on line 6 and constituted by an extractant selective for uranium dissolved in an organic diluent.
The two streams flow through the contactor as discrete phases, the lighter organic solvent stream being uppermost, but during their movement through the contactor the streams are subject to gentle intermingling causing intimate contacting of each phase with the other as will be described in detail subsequently.
The phosphoric acid raffinate leaves the contactor on line 7, now containing little uranium and negligible amounts of entrained organic solvent, and is pumped directly, and without further treatment, to the fertiliser production plant. The uranium-rich organic solvent stream, which leaves the contactor on line 8, passes to a stripping stage 9 where the uranium values are stripped and is recycled on line 6 to the contactor 5.
The stripping stage 9 is constituted by a second continuous contactor, which is similar to contactor 5, and in which the uranium-rich solvent stream is contacted with a stripping stream on line 10. A side stream of phosphoric acid from line 7 is pumped on line 11 to tank 12 where it is mixed with metallic iron, a ferrous salt or other reducing agent entered on line 13 and pumped out on line 10 as the stripping stream. In the contactor 9, the reducing agent reduces the uranium values to quadravalent form and renders them preferentially soluble in the phosphoric acid to which they are transferred. The strip phosphoric acid leaving contactor 9 on line 14 now contains uranium values at a concentration substantially higher than that of the uranium in the phosphoric acid feed to contactor 5 and is treated after reoxidation in known manner for recovery of the uranium.Part of the uranium loaded strip acid is recycled on line 15 to tank 12.
As will be seen, the use of the contactor 5 for the extraction of the uranium values from the phosphoric acid feed eliminates the need for equipment, other than that normally provided in the phosphoric acid plant, for removing soluble organic material from the feed. More important, the equipment normally supplied for removing contained organic solvent from the raffinate on line 7 is no longer needed; in experiments on phosphoric acid from Moroccan phosphate rock, the phosphoric acid raffinate on line 7 was found to contain less than 20 parts per million of hydrocarbon, whereas it is generally accepted that the maximum permitted figure is 50 ppm. Similarly the use of the contractor 9 in place of the customary mixer-settlers for the stripping stage ensures minimum loss of organic solvent to the strip acid on line 14.
The preferred organic solvent is a mixture of a dialkylphosphoric acid and a trialkylphosphine oxide dissolved in an organic solvent, such as kerosene.
The best extractant at present known is a mixture of di(2-ethylhexyl) phosphoric acid (D2EHPA) and trioctylphosphine oxide (TOPO).
Each of the contactors 5 and 9 is generally as described in U.K. Patent No. 972,035. As illustrated in
Figures 1 and 2, the contractor comprises a stationary drum 16, which has a near-horizontal axis, and in which rotates a rotor consisting of a shaft 17 carrying a series of discs 18 which separate the interior of the drum 16 into a sequence of compartments 20. In each compartment 20, there is a ring of buckets 21, carried by the discs 18 and extending across the compartment. Those buckets rotate with the shaft 17 and discs 18, to cause intermingling of the two phases passing through the contactor. The end compartments 22 do not have buckets 21. As shown in Figure 1, the discs 18 do not extend entirely to the drum 16, and instead leave an annular gap 23 (Figure 2) between the edge of each disc and the drum for the passage of the phases through the drum.
Although Figure 1 shows contactors having only six discs 18, and five compartments disregarding the end compartments, it is to be understood that in
practice a larger number of compartments are
employed, the actual number depending on the
parameters of the process.
As previously stated, the aqueous phase - the
dilute phosphoric acid - and the organic phase -the solvent stream from line 6 - pass through the
contactor 5 as discrete phases, the rotor of the
contactor being turned at a slow speed of a few
revolutions per minute in order to avoid the vigorous
intermixing that takes place in a mixer settler.Thus,
as shown in Figure 2 the organic and aqueous
phases indicated respectively at 28 and 29 form a
stable interface 30, which is usually located on the
axis of the contacton The phases move from com
partment to compartment via the annular gaps 23
and, in each compartment, are subject to gentle
intermingling by the rotary action of the buckets 21;
as the rotor turns, the buckets raise aqueous phase
into the organic phase 28 and shower the latter into the former, the discharge from each bucket being distributed over the arcuate path of the buckets and the droplets of the aqueous phase returning through the organic phase back to the aqueous phase 29.
Similarly, on the descent of each bucket, organic phase is taken down and released into the aqueous phase as droplets which return to the organic phase 28. This gentle intermingling of the phases occurs in each compartment 20 and the phases are thus subject to multi-stage contacting. As each phase moves through the other phase in droplet form, the area of contact between the two phases is large and the contacting process is therefore enhanced. In the final compartment 22, the two phases settle out completely, so that, when discharged on lines 7 and 8 each phase contains a little of the other phase.
The operation of contactor 9 is exactly similar, the lower aqueous phase being constituted by the - phosphoric acid on line 10 and the upper organic phase by the organic solvent stream from line 8.
Again, there is negligible loss of each phase to the other phase on exiting from the contactor.
Claims (5)
1. A process for extracting uranium values from aqueous phosphoric acid using an organic solvent containing an extractant selective for uranium
characterised in that a stream of the aqueous phosphoric acid and a stream of the organic solvent are passed in separate phases through a continuous rotary liquid/liquid contactor in which the aqueous phosphoric acid and the solvent are gently interm
ingled during their passage.
2. A process according to claim 1, in which the
uranium values are stripped from the uranium rich solvent stream from the contactor by contacting that stream with a stripping stream in a second continuous rotary contactor.
3. A process according to claim 2, in which the stripping stream is, or contains, phosphoric acid containing a reducing agent.
4. A process according to any one of the preced
ing claims, in which the uranium values in the feed stream of aqueous phosphoric acid is oxidised to hexavalent form prior to entry to the contactor in which that feed stream is intermingled with the
organic solvent.
5. A process according to any one of the preced:
ing claims in which the organic solvent comprises a
mixture of di-(2-ethylhexyl) phosphoric acid and trioctylphosphine oxide dissolved in an organic
diluent.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8026084A GB2082154B (en) | 1980-08-11 | 1980-08-11 | Extracting uranium values from aqueous phosphoric acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8026084A GB2082154B (en) | 1980-08-11 | 1980-08-11 | Extracting uranium values from aqueous phosphoric acid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2082154A true GB2082154A (en) | 1982-03-03 |
| GB2082154B GB2082154B (en) | 1983-06-02 |
Family
ID=10515364
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8026084A Expired GB2082154B (en) | 1980-08-11 | 1980-08-11 | Extracting uranium values from aqueous phosphoric acid |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2082154B (en) |
-
1980
- 1980-08-11 GB GB8026084A patent/GB2082154B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2082154B (en) | 1983-06-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |