CN109837401B

CN109837401B - Process for extracting uranium from phosphoric acid

Info

Publication number: CN109837401B
Application number: CN201711351569.2A
Authority: CN
Inventors: 黄飞熊
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-11-29
Filing date: 2017-12-15
Publication date: 2022-01-28
Anticipated expiration: 2037-12-15
Also published as: CN109837401A

Abstract

The invention relates to a process for extracting uranium from phosphoric acid, which comprises a first cyclic reaction and a second cyclic reaction; the first cycle is with D₂T or D₂D (higher uranium extraction capacity)Poor, less expensive) extractant for continuous extraction of uranium (increased by 5-fold in uranium content) from phosphoric acid (uranium content of about 65-70 μ g/ml in five stages (MS 101-105) and back-extraction with 30% Fe content²⁺The uranium is continuously back extracted into the phosphoric acid (uranium concentration is 34.7 times after the uranium is concentrated) by three sections (MS 106-108) of the phosphoric acid (reducing acid), the content of the first cycle uranium can reach more than 10g/l, and once the reducing acid Fe is used²⁺The concentration is insufficient and must be immediately replenished to avoid Fe²⁺The oxidation (MS 106-108) reaction tank must be water-sealed and passivated with nitrogen, and B-73 (Fe)³⁺/Fe²⁺) The ratio of (A) to (B) is controlled to be a fixed value, thereby overcoming the defect of poor back-extraction efficiency of the first cycle, and D used in the reaction of the second cycle₂T or D₂The D extractant and D-45 uranium are maintained at a constant value of more than 10g/l, and the extractant containing high-concentration uranium is fed at a stable speed, so that the iron content of the product is greatly reduced, and the product purity is improved.

Description

Process for extracting uranium from phosphoric acid

Technical Field

The invention relates to a uranium extraction process; more particularly, the present invention relates to a uranium phosphate extraction process capable of increasing the efficiency of the first recycle stripping section and reducing the severe emulsification phenomenon of the second recycle stripping section.

Background

Firstly, the ferrous ion (Fe) of the reducing acid B-73 is found in the back extraction section of the first cycle reaction²⁺) If the amount of the reducing acid is too low, the reducing acid cannot extract the uranium in the organic phase, and the uranium in the reducing acid is carried away by the organic extractant, although it is known from past experience that ferrous ions (Fe) are supplemented²⁺) But the ferrous ion (Fe) is replenished only when an abnormality is encountered²⁺) This results in labor and therefore the necessity of solving the problem of poor efficiency of the stripping section of the first cycle reaction.

Then, when the second circulation reaction is carried out, the back extraction section is found to generate a serious emulsification phenomenon, so that the organic and ammonium carbonate liquid can not be separated, the machine must be stopped to clean the emulsified substances, the emulsified substances are stored in a 50 gallon barrel and are stored, the machine is restarted to operate after the liquid level in the machine is replenished, the machine is stopped again to clean due to the serious emulsification generated in other days, and after the emulsified substances are cleaned by switching on and switching off for a plurality of times, the machine is still not cleanedThe method only needs to pump the organic matters in the V-205 and V-209 tanks into the first circulation to reconstitute D₂D(0.4mol D₂EHPA, 0.1mol DBBP-Kerosene), and reformulating D₂D is pumped into V-205 to be started up again, but emulsification still occurs after 3 hours of operation, but the emulsification problem of the back extraction section of the second cycle is found to exist already by looking up the previous field record, but the dosage of the medicament used in the previous reaction of the second cycle is small, the replacement is easy, and the improvement is not thorough.

In addition, the first cycle reaction and the second cycle reaction are linked, so it is necessary to improve the problem of poor efficiency of the first cycle reaction and the second cycle back extraction at the same time.

Disclosure of Invention

In view of the above, the present invention provides a uranium phosphate extraction process.

In order to achieve the above object, the present invention provides a uranium phosphate extraction process, which includes a first cyclic reaction and a second cyclic reaction;

the first circulation reaction comprises an extraction section and a back extraction section, wherein D used by the back extraction section₂T (0.5M bis (2-ethylhexyl) phosphate (D)₂EHPA) and trioctylphosphine oxide-Kerosene (0.125M TOPO-Kerosene)) were mixed and the concentration of the reducing acid P was maintained constant₂O₅The concentration of the reducing acid should be controlled to a constant value, and the concentration of the reducing acid should be supplemented immediately when the concentration of the reducing acid is insufficient, and B-73 (Fe)³⁺/Fe²⁺) The ratio of (A) to (B) is controlled to be constant and B-62 (Fe) is reduced²⁺) To reduce iron and hydrogen peroxide (H) in the second cycle₂O₂) The amount of the compound and impurities of the product;

the second circulation reaction comprises an extraction section and a back extraction section, wherein the back extraction section uses D₂D or is D₂T is used as an extractant, D-45 uranium is maintained at a high content, the concentration of ammonium carbonate for stripping is also maintained at a constant value, Aq precipitated at the bottom of the reaction tank is discharged at regular time, the extractant containing high-concentration uranium is fed at a stable speed, and Org: the ratio of Aq must be maintained constant.

Further, itIn the first cyclic reaction stripping section D₂T is 0.5M, D₂T is a mixture of 0.5M bis (2-ethylhexyl) phosphate and 0.125M trioctylphosphine oxide-kerosene.

Further, wherein the reducing acid P in the first recycle stripping section₂O₅The concentration was 30%.

Further, wherein B-73 (Fe) is present in the first stripping section³⁺/Fe²⁺) The ratio of (A) to (B) is between 1.0 and 2.5.

Further, wherein the extractant D in the second cyclic reaction stripping section₂The concentration of D was 0.4M.

Further, the uranium content of D-45 in the second cyclic reaction stripping section is more than 10 g/l.

Further wherein the ammonium carbonate concentration in the second recycle stripping section is 2M.

Further, wherein the second recycle stripping section has an Org: the ratio of Aq is 2: 1.

the invention has the following beneficial effects:

the uranium phosphate extraction process provided by the invention is to extract Fe³⁺/Fe²⁺The ratio of the first and second phases is controlled to be a fixed value so as to overcome the poor efficiency of the first cyclic reaction stripping section and improve the efficiency of the first cyclic reaction stripping section; and the serious emulsification phenomenon generated in the back extraction section in the second circulation reaction can be reduced, the content of organic uranium in the back extraction section of the second circulation reaction is increased, the iron content of the product is reduced, and the purity of the product is further increased.

Drawings

FIG. 1: the invention relates to a first circulation reaction flow chart of a uranium phosphate extraction process;

FIG. 2: the invention relates to a second circulation reaction flow chart of a uranium phosphate extraction process.

Wherein,

1-first cycle reaction; 11-a first cyclic extraction section; 12-a first loop stripping section;

2-second cycle reaction; 21-a second cyclic extraction section; 22-second cycle stripping section.

Detailed Description

Other features and advantages of the present invention will be further illustrated by the following examples, which are intended to be illustrative only and not limiting.

Referring to fig. 1 and fig. 2, fig. 1 is a first cyclic reaction flow chart of a uranium phosphate extraction process of the present invention, and fig. 2 is a second cyclic reaction flow chart of the uranium phosphate extraction process of the present invention.

The invention relates to a process for extracting uranium from phosphoric acid, which comprises a first cyclic reaction and a second cyclic reaction.

The first circulation reaction comprises an extraction section and a back extraction section, wherein the first circulation reaction extraction section mainly extracts hexavalent uranium, and the chemical reaction formula of the first circulation reaction extraction section is as follows:

in the reaction formula, HX is Di (2-ethylhexyl) phosphate (Di (2-ethylhexyl) phosphate, D₂EHPA) and TOPO is Tri-n-octylphosphine oxide (TOPO); in addition, the first circulation reaction back extraction section mainly utilizes reducing acid to remove hexavalent uranium (U)⁶⁺) Back extraction into tetravalent uranium (U)⁴⁺) The chemical reaction formula is as follows:

in order to investigate the reason why the second-cycle stripping section produces emulsification, the present inventors first performed on-site sampling, and the sampling results are shown in the following table (one).

Watch 1

The sampling of the B-83 uranium is only performed once at 08:30 every day, and when the concentration of the B-51 uranium is less than that of the B-83 uranium, the reducing acid cannot perform back extraction of the B-51 uranium, and is carried away by an extractant, so that the concentration of the B-73 uranium is gradually reduced.

In order to investigate the reason of the poor efficiency of the back-extraction section of the first cycle reaction, the present inventors analyzed the conventional operation method, raw material concentration, equipment and chemical reactants, and the analysis results are as follows:

discussing the relationship between the concentration of raw materials, chemical reaction and back extraction efficiency:

the concentration of B-51U detected on day three 08:30 of Table (I) above was 315. mu.g/ml-0.315 g/l, if B-51U is to be completely stripped by reducing acid B-73U

And U must be used

Fe (b) of²⁺To react.

But B-73settlerFe²⁺In an amount of only 2.7g/l, and B-72 Fe²⁺The amount was 12.4g/l and the B-73Mixer was pumped at a rate of 7.2l per hour, while 500l/hr of recycle acid was pumped into the B-73 Mixer.

Trial calculation of B-73Mixer Fe from the above information²⁺Should be as theoretical as

And this Fe²⁺Can only be mixed with

U of (1)⁶⁺A chemical reaction is carried out.

If Fe is therefore²⁺The content of the uranium is relatively reduced, if the B-51 uranium is required to be efficiently back-extracted, the content of the B-73Fe is relatively reduced²⁺The content must be maintained above a certain value.

Discussing the relationship between the operating method and equipment factors and the reaction efficiency:

suppose that B-51 (U: 0.3g/l) is pumped into MS-108 at a rate of 250l/hr to strip with the chlorogenic acid B-73, so that the total amount of uranium pumped per hour is 0.3x250 to 75g, which would require uranium

Fe (b) of²⁺Performing back extraction, and pumping reducing acid B-72 into MS-108 at a rate of 7.2l/hr in an amount of per hour

And theoretically Fe of B-72²⁺Continuously injecting into MS-108 at a rate of 7.2l/hr to supplement Fe of B-73²⁺Consumption (assuming Fe)²⁺Not oxidized by O2), high efficiency can be achieved by stripping, if B-72 is not continuously blanked and Fe of B-73²⁺35.3g of Fe was continuously consumed per hour²⁺The gradual decrease of the content results in incomplete stripping of B-51 uranium and thus poor overall stripping efficiency, so that the operation needs to be careful about correct flow rates of the organic extractant and the reducing acid and normal feeding, and about B-73Fe²⁺If the concentration is required to be kept above a fixed value at any time and the concentration does not reach the standard, the concentration needs to be supplemented, and finally, if the feed pump, the pipeline and the storage tank are leaked, the feed pump, the pipeline and the storage tank are immediately sealed to avoid Fe²⁺By O in the atmosphere₂And (4) oxidizing.

Discussing Fe³⁺/Fe²⁺The relation between the ratio and the stripping efficiency is as follows:

while utilizing Fe²⁺The chemical reaction formula for back extraction is as follows:

and Fe ═ Fe²⁺+Fe³⁺When B-73Fe²⁺Fe at decreasing time³⁺But relatively increased, so that Fe³⁺Increase to a certain concentration (Fe)³⁺/Fe²⁺Ratio of 5 or more) the reaction proceeds in reverse.

Watch 2

From the above table (II), Fe³⁺/Fe²⁺The ratio must be controlled below a specific fixed value, and the reduced acid can be normally back-extracted.

Discussing Fe³⁺/Fe²⁺、U⁶⁺/U⁴⁺The relation with the back extraction efficiency especially imitates the following test of the process conditions:

(1) discussing Fe²⁺ _aqAnd U⁶⁺ _orgThe relationship of (1):

taking out the reducing acid and B-62 (U: 0g/l, Fe)²⁺: 32.6g/l) in 100ml portions, and adding a little H₂O₂Making Fe²⁺After the change, 50ml of B-51 (U: 259. mu.g/ml) with water content of 60 ℃ is added, and the mixture is shaken in a separating funnel for 20 minutes, and then the acid analysis is carried out by clarification, and the analysis number is shown in the following table (III).

Watch (III)

As is clear from the above Table (III), when the reducing acid contained no uranium, 2.7g/l of Fe²⁺Is sufficient to completely strip the B-51 uranium.

(2) Taking reducing acid and B-62 (U: 0g/l, Fe)²⁺: 42.3g/l) of each 100ml and adding different amounts of H as in (1) above₂O₂Making Fe²⁺After the completion of the reaction, 50ml of B-51 (U: 207.6. mu.g/ml, Fe: 118.1. mu.g/ml) was added thereto, and after back-extraction, the analytical data were as shown in the following Table (IV).

Watch (IV)

From the above Table (IV), it is understood that Fe is contained when the reducing acid does not contain uranium_aq ²⁺1.0g/l should be sufficient to completely strip B-51 uranium and also Fe_aq ²⁺The solid reducing acid with negative correlation with the organic Fe contains Fe³⁺The more the organic iron content increases, the more the organic iron content increases.

(3) Discussing Fe³⁺/Fe²⁺、U⁶⁺/U⁴⁺Relationship to chemical reactions:

taking reducing acid B-72 (U)⁴⁺：7.59g/l、Fe²⁺: 28.4g/l) of each 100ml, and then adding H₂O₂Making Fe²⁺After the change, 50ml of B-51 (U: 259. mu.g/ml, Fe: 120. mu.g/ml) was added, respectively, and the analytical data after back extraction are shown in the following table (five).

Watch (five)

The extractant with high content of uranium, namely Fe, can be known from the table (V) for reverse extraction of high content of chlorogenic acid³⁺/Fe²⁺Ratio of

Therefore, the stripping cannot be performed, and when the ratio is

Can be back extracted to fix Fe³⁺/Fe²⁺Ratio and U⁶⁺/U⁴⁺Is in positive correlation, and from this, Fe is known³⁺/Fe²⁺The lower the ratio of (A) is, the better the stripping efficiency is.

(4.) discussing Fe³⁺/Fe²⁺、U⁶⁺/U⁴⁺Concentration versus chemical reaction:

take B-73 (U)⁴⁺：7.7g/l、U：7.87g/l、Fe²⁺: 10.6g/l, Fe: 31.4g/l) and adding H₂O₂Making Fe²⁺After the change, 50ml of B-51 (U: 25.9. mu.g/ml, Fe: 120. mu.g/ml) was added, respectively, and the analytical data after back extraction are shown in the following Table (six).

Watch (six)

From the sixth Table, it can be seen that Fe is contained when the reducing acid contains high uranium³⁺/Fe²⁺Ratio of

At this time, the B-51 uranium cannot be stripped, which may be caused by the large difference between the concentrations of the aqueous phase uranium and the organic phase uranium.

(5) Discussing Fe again³⁺/Fe²⁺、U⁶⁺/U⁴⁺In connection with chemical reactions:

100ml of B-72 (U) was taken⁴⁺：7.7g/l、U：7.87g/l、Fe²⁺: 10.6g/l, Fe: 31.4g/l) and 50ml of B-51 (U: 207.6. mu.g/ml, Fe: 118.1. mu.g/ml) were subjected to the back extraction as described in (3) and (4), and the analysis data after the back extraction is shown in the following Table (seven).

Watch (seven)

From the above table (VII), it can be seen that Fe is present³⁺/Fe²⁺Ratio of

Normal back extraction can be performed, but Fe³⁺/Fe²⁺Ratio of

The back extraction cannot be performed.

As can be seen from the above experiments, D used in the first-cycle reaction stripping section₂T(0.5M D₂EHPA, 0.125M TOPO-Kerosene) concentration is maintained at 0.5M, reducing acid P₂O₅The concentration should be controlled to about 30%, and the reducing acid should be supplemented immediately when the concentration is insufficient, and B-73 (Fe)³⁺/Fe²⁺) The ratio of (A) to (B) is controlled to be constant (between 1.0 and 2.5), and B-62 (Fe) is reduced²⁺) To reduce iron bloom and hydrogen peroxide (H) in the second cycle reaction₂O₂) The amount of (c) and the iron content of the product.

Since B-73 (Fe)³⁺/Fe²⁺) After the ratio of (A) is controlled to be a fixed value, the abnormal phenomenon of the stripping section of the first cycle reaction does not occur any more, and the tetravalent uranium is stripped smoothly all the time.

The second cyclic reactive extraction comprises an extraction section and a back extraction section, wherein the chemical reaction formula of the second cyclic reactive extraction section is as follows:

in addition, the extractant used in the second cyclic reaction stripping section is D₂T and D₂D, the back extraction process is divided into two steps:

by using D₂T is used as a first step of an extracting agent, and the chemical reaction formula is as follows:

step two, the chemical reaction formula is as follows:

by using D₂D, taking the D as a first step of the extracting agent, wherein the chemical reaction formula is as follows:

step two, the chemical reaction formula is as follows:

in order to investigate the reason why the second-cycle reaction stripping section produces severe emulsification, the present inventors analyzed the existing operation methods, raw materials, equipments and chemical reactants, and the analysis results are as follows:

whether emulsification is correlated with ammonium carbonate concentration is explored:

test 1: mixing the emulsified organic extractant with ammonium carbonate with a new configuration concentration of 2M in a ratio of 1: 1 and shaking to uniformly mix the emulsified organic extractant and ammonium carbonate, wherein the organic phase is in an emulsified state after shaking.

Test 2: mixing the emulsified organic extractant and ammonium carbonate with new configuration concentration of 1M in a ratio of 1: 1 and shaking to uniformly mix the emulsified organic extractant and ammonium carbonate, wherein the organic phase is in an emulsified state after shaking.

Test 3: the emulsified organic extractant is mixed with solid ammonium carbonate with purity of more than 90%, the solution is saturated and stirred, and the organic phase is still in an emulsified state after stirring.

Therefore, it can be seen from the above experiments 1-3 that different concentrations of ammonium carbonate can not improve the emulsification, and the concentration of ammonium carbonate is not a factor affecting the emulsification.

To investigate whether emulsification is associated with organic extractant concentration:

test 4: emulsifying the organic extractant (D)₂: 0.44M) to kerosene in a ratio of 1: 1 mixing and shaking to mix the emulsified organic extractant homogeneously with the kerosene, and after shaking the mixture was found to have a clear upper layer but a lower layer which was still emulsified.

Therefore, when the emulsified organic extractant (0.44M phosphoric acid) was further diluted twice with kerosene, the amount of suspended particles in the emulsion decreased, and it was found that the concentration of the extractant was correlated with the emulsification phenomenon.

Whether emulsification and organic uranium content are related is discussed:

test 5: mixing emulsified organic extractant (U: 1.5g/l) with D-45 (D)₂: 0.44M, U: 6g/l) in a ratio of 1: 1 and shaking to mix the emulsified organic extractant with D-45 uniformly, and after shaking, the emulsion was found to begin to agglomerate and sink to make the solution clear.

Test 6: mixing emulsified organic extractant (U: 1.5g/l) with D-45 (D)₂: 0.44M, U: 6g/l) in a ratio of 1: 2 mixing and shaking to mix the emulsified organic extractant with D-45 uniformly, and after shaking, the emulsion is found to be rapidly agglomerated and sink, and the solution is clarified more quickly.

From the above experiments, it can be seen that the total uranium amount in experiment 5 is

Total uranium of test 6

The emulsion can be combined with uranium in the organic extractant and then precipitated, and the more the content of uranium, the faster the compound generated precipitates, so that the emulsification phenomenon is directly related to the content of organic uranium, and the emulsification problem can be solved by increasing the uranium content of the organic extractant.

The correlation of emulsification with uranium content and extractant concentration was explored:

test 7: emulsifying the organic extractant (D)₂：0.44M、U：1.5g/l)、D-45(D₂: 0.44M, U: 6g/l) with D-71(2M ammonium carbonate, U: 2g/l) in a ratio of 1: 1: 2 and shaking, and finding that the organic extractant still generates an emulsified state.

As can be seen from test 7, the total uranium content was

And an extractant D₂Is composed of

In trial 7, uranium ammonium carbonate (AUT) is not easily formed and the organic liquid is emulsified because the uranium content is low and the extractant concentration is high.

Test 8: emulsifying the organic extractant (D)₂：0.44M、U：1.5g/l)、D-45(D₂: 0.44M, U: 6g/l), kerosene and D-71(2M ammonium carbonate, U: 2g/l) in a ratio of 2: 3: 1: 3 mixing and shaking, so that after shaking, yellow crystals are generated and the emulsification of the organic liquid is reduced to make the solution clear.

As can be seen from test 8, the total uranium content was

And an extractant D₂Is composed of

Since the concentration of the organic extractant is diluted to 0.37M by keroseneUranium ammonium carbonate (AUT) is formed when the amount of uranium reaches 3.0g/l, the emulsification of the organic liquid is reduced and clarified, and the dilution of the organic extractant concentration in comparison with experiment 7 shows that the emulsification can be improved.

Test 9: emulsifying the organic extractant (D)₂：0.44M、U：1.5g/l)、D-45(D₂: 0.44M, U: 6g/l), kerosene and D-71(2M ammonium carbonate, U: 2g/l) in a ratio of 2: 3: 1: 6 mixing and shaking, the organic extractant produces emulsification.

As can be seen from test 9, the total uranium content was

And an extractant D₂Is composed of

Although the concentration of the organic extractant was diluted to 0.37M with kerosene, uranium ammonium carbonate (AUT) was not easily produced when the total uranium amount was only 2.75g/l, and the organic liquid was emulsified, and it was found that the total uranium amount was maintained at 3.0g/l or more, and no emulsification occurred, as compared with test 8.

Test 10: emulsifying the organic extractant (D)₂：0.44M、U：1.5g/l)、D-45(D₂: 0.44M, U: 6g/l), kerosene, D-71(2M ammonium carbonate, U: 2g/l) and D-45 (D)₂: 0.44M, U: 6g/l) in a ratio of 2: 3: 1: 6: 6 mixing and shaking, the result was the same as that of test 8, yellow crystals were produced and the emulsification of the organic liquid was decreased to clarify the organic liquid.

As can be seen from test 10, the total uranium content was

And an extractant D₂Is composed of

When the concentration of the organic extractant is diluted to 0.4M and the total uranium content is 3.83g/l, uranium ammonium carbonate (AUT) is produced and the solution is clarified by the drop in the emulsification of the organic liquid.

Test 11: emulsifying the organic extractant (D)₂：0.44M、U：1.5g/l)、D-45(D₂: 0.44M, U: 6g/l), kerosene and D-71(2M ammonium carbonate, U: 2g/l) in a ratio of 1: 2: 1: 2 mixing and shaking, although the amount of yellow crystals produced decreases, the emulsification of the organic liquid can be improved and the solution becomes clear.

As can be seen from test 11, the total uranium content is

And an extractant D₂Is composed of

Although the total uranium content in trial 11 was less than 3g/l, the concentration of the organic extractant was only 0.33M and the amount of uranium ammonium carbonate (AUT) formed was reduced, and it was found that the dilution of the organic extractant concentration improved the emulsification phenomenon compared to trial 7.

Test 12: taking emulsified organic extractant (D)₂：0.44M、U：1.5g/l)22.5ml、D-32(D₂: 0.44M, U: 3.5g/l)30ml, kerosene 15ml and D-71(2M ammonium carbonate, U: 2g/l)35ml were mixed and shaken, resulting in emulsification of the organic liquid.

As can be seen from test 12, the total uranium content is

And an extractant D₂Is composed of

Although the concentration of the organic extractant is diluted to be below 0.4M, the total uranium content is less than 3g/l, and uranium ammonium carbonate (AUT) is not easy to generate, so that the organic liquid generates an emulsification phenomenon.

Test 13: taking emulsified organic extractant (D)₂：0.44M、U：1.5g/l)35ml、B-32(D₂: 0.4M, U: 0.005g/l)50ml, kerosene 20ml and D-71(2M ammonium carbonate, U: 2g/l)35ml were mixed and shaken, as a result of which only the organic liquid was clarified.

As can be seen from test 13, the total uranium content is

And an extractant D₂Is composed of

When the organic extractant concentration was diluted to 0.34M and the total uranium content was only 0.82g/l, no uranium ammonium carbonate (AUT) was produced but the organic liquor was clarified.

Test 14: taking emulsified organic extractant (D)₂：0.44M、U：1.5g/l)35ml、B-32(D₂: 0.4M, U: 0.005g/l)50ml, kerosene 20ml and D-71(2M ammonium carbonate, U: 2g/l)53ml were mixed and shaken, as a result of which only the organic liquid was likewise clarified.

As can be seen from test 14, the total uranium content is

And an extractant D₂Is composed of

When the organic extractant concentration is diluted to 0.34M and the total uranium content is 1.0g/l, uranium ammonium carbonate (AUT) is not easily produced but the organic liquid is clarified.

Then, the reason for the emulsification is proved by experiments, and the reason for the emulsification is judged by experiments of rapidly recovering the emulsified organic liquid from clarification according to the experiments 1 to 14, wherein the reason for the emulsification is that the uranium content is relatively low (2 to 3g/l), uranium ammonium carbonate (AUT) is not completely crystallized to form fine particles to be suspended in the organic phase, and the emulsification phenomenon cannot be caused when the uranium content is sufficient, and the experiments prove that:

test 15: taking D-45 (D)₂: 0.45M, U: 6.13g/l)50ml of a reaction mixture with D-71(2M ammonium carbonate, U: 2g/l)100ml were mixed and shaken, resulting in a small amount of yellow crystals and a clear organic liquid.

As can be seen from test 15, the total uranium content is

And an extractant D₂At 0.45M, the organic extractant concentration in trial 15 was higher, but uranium ammonium carbonate (AUT) was produced when the total uranium content was greater than 3.0g/l, and no emulsification of the organic liquid occurred.

Test 16: taking D-45 (D)₂: 0.45M, U: 2.81g/l)30ml of a reaction product with D-71(2M ammonium carbonate, U: 2g/l)60ml were mixed and shaken, as a result of which the organic liquid quickly emulsified and had to be clarified after a long period of time.

As can be seen from test 16, the total uranium content is

Uranium ammonium carbonate (AUT) is not easily formed and an emulsification phenomenon is generated because the total uranium amount is less than 3g/l, and thus it can be confirmed that the emulsification phenomenon generated by MSV-208 is caused by a low uranium content.

Test 17: taking D-45 (D)₂: 0.45M, U: 2.81g/l)45ml of ammonium chloride mixed with D-71(2M ammonium carbonate, U: 2g/l)45ml were mixed and shaken, as a result of which the organic liquid quickly emulsified and had to settle after a long period of time.

As can be seen from test 17, the total uranium content is

The formation of uranium ammonium carbonate (AUT) and the emulsification caused by the total uranium amount of less than 3g/l are not easy, and thus it can be proved that the emulsification caused by MSV-208 is also caused by the low uranium content.

Therefore, the results of the above tests 1 to 17 can be combined to form the following table (eight).

Watch (eight)

From the dry-based analysis of the uranium ammonium carbonate (AUT) products and emulsions listed in table (eight), it was found that the content of impurity components increased as the uranium content decreased.

Therefore, it can be deduced from the above experiments that the emulsion is formed by the poor crystallization of uranium ammonium carbonate, and because the content of uranium is not enough to react with 2M ammonium carbonate in the reaction tank, ammonium carbonate can easily elute iron and phosphate in the organic phase to form a complex ionic compound of uranium ammonium carbonate and phosphate, and because these ionic compounds are very fine and not easy to precipitate, they are suspended in the organic phase and cause emulsification.

It is deduced from the above test results that the emulsification is caused by the continuous recycling of Kerosene (Kerosene) as the extractant in the process, and the concentration of the extractant is gradually increased to 0.44M under the condition that the Kerosene (Kerosene) is gradually volatilized, so that the uranium capturing capability of the extractant is better than that of the extractant with the concentration of 0.4M, and D is higher than that of the extractant with the concentration of 0.4M₂T is compared with D₂D has stronger uranium extraction capability (D)₂T average uranium extraction capacity of D₂D1.6 times) and when the uranium content is low, the organic agent of the second loop reactive extraction stage will extract other impurities (iron being the most extracted impurities) in addition to the uranium, which will also elute into the ammonium carbonate solution as the uranium during the stripping of the second loop reactive stripping stage, disturbing the purity of the uranium ammonium carbonate (AUT) product, although D is low₂D(D₂EHPA + DBBP) has only D uranium extraction capacity₂T(D₂EHPA + TOPO) but using D at a concentration of 0.4M₂No emulsification was observed.

In order to avoid emulsification in the second recycle stripping section, 0.4M D was used in the stripping section₂D or D with concentration less than 0.4M₂T, D-45U used in the stripping section is maintained to be more than 10g/l, Aq precipitated at the bottom of the reaction tank is discharged at regular time, and an extractant containing high-concentration uranium is fed at a stable speed, wherein the ratio of Org: the ratio of Aq must be maintained at 2: 1.

the operation of the second circulation reaction stripping section is carried out for a month, the improved stripping efficiency is up to 97 percent, and the stripped U₃O₈The purity is maintained to be more than 96 percent, which really proves the improvement of the product quality, and the emulsification phenomenon is not generated in the back extraction process, thereby greatly reducing the waste of manpower and material resources.

The invention has the advantages that:

mixing Fe³⁺/Fe²⁺The ratio of (A) is controlled to be a fixed value so as to overcome the condition that the efficiency of the reaction stripping section of the first cycle is poor.

The content of organic uranium in the second circulation reaction stripping section is increased, so that the iron content of the product is reduced, and the purity of the product is increased.

In summary, the above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, so that all equivalent changes made in the description and drawings of the present invention should be included in the scope of the present invention.

Claims

1. A uranium phosphate extraction process is characterized by comprising a first cyclic reaction and a second cyclic reaction;

the first circulation reaction comprises a first circulation reaction extraction section and a first circulation reaction stripping section, wherein an extracting agent D used by the first circulation reaction stripping section₂The concentration of T is maintained constant, the concentration of the reducing acid phosphorus pentoxide is controlled constant, the reducing acid is supplemented immediately when the concentration of the reducing acid is insufficient, and Fe of B-73³⁺/Fe²⁺The ratio of (A) to (B) is controlled to be constant, and the Fe content of B-62 is reduced²⁺So as to reduce the dosage of iron and hydrogen peroxide in the second cycle and impurities of the product;

the second circulation reaction comprises a second circulation reaction extraction section and a second circulation reaction stripping section, wherein the second circulation reaction stripping section uses D₂D or is D₂T is used as an extractant, D-45 has high uranium content, the aqueous solution precipitated at the bottom of the reaction tank is discharged regularly, the concentration of ammonium carbonate for stripping is also kept constant, the extractant containing high uranium concentration is fed at a stable speed, and the organic liquid Org: the proportion of the aqueous solution Aq is required to be maintained at a constant value;

wherein D in the first cyclic reaction stripping section₂T is 0.5M, D₂T is formed by mixing 0.5M bis (2-ethylhexyl) phosphate and 0.125M trioctylphosphine oxide-kerosene;

wherein the extractant D2D in the second circulating reaction stripping section is formed by mixing 0.4mol of bis (2-ethylhexyl) phosphate and 0.1mol of dibutyl butyl phosphonate-kerosene;

wherein, the concentration of the phosphorus pentoxide of the reducing acid in the first circulation reaction back extraction section is 30 percent;

wherein Fe of B-73 in the first cyclic reaction stripping section³⁺/Fe²⁺The ratio of (A) to (B) is between 1.0 and 2.5;

wherein, the extractant D in the second circulation reaction back extraction section₂The concentration of D is 0.4M, the extractant D₂The concentration of T is less than 0.4M;

wherein the uranium content of D-45 in the second circulating reaction stripping section is more than 10 g/l;

wherein the concentration of ammonium carbonate in the second loop reaction stripping section is 2M;

wherein, the organic liquid Org in the second circulation reaction stripping section is as follows: the ratio of the aqueous solution Aq is 2: 1.