Method of selective americium removal from nitric water phase

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy and can be used during recycling and disposal of the spent nuclear fuel. Method includes americium extraction from nitric water phase by means of its circulation in the first extractor, washing of the obtained organic phase in the second extractor, and selective reextraction of the americium in the third extractor. Then the lanthanides reextraction is performed from the obtained phase by means of its circulation in the forth extractor.

EFFECT: selective extraction of the americium is ensured from the nitric water phase containing americium, curium and fission products including lanthanides and yttrium, and optionally containing uranium, plutonium and neptunium in trace quantities.

23 cl, 2 dwg, 10 tbl, 3 ex

 

The technical field to which the invention relates

The present invention relates to a method that allows selectively removing americium from nitric acid aqueous phase containing americium, and curium fission products, including the lanthanides, but not containing uranium, plutonium and neptunium or containing these three last element only in trace amounts.

This method finds application in the field of processing and disposal of irradiated nuclear fuel in which it is of special interest in the purification of americium refined, resulting from the implementation of methods for the extraction and purification of uranium and plutonium, such as the PUREX ways and COACH™.

The level of technology

Methods that allow to extract and purify the uranium and plutonium present in the solution resulting from the dissolution of irradiated nuclear fuel, such as the PUREX method (which is currently used in plants for the reprocessing of irradiated nuclear fuel) and the method COACH™ (which is described in the international PCT application WO 2007/135178, [1]), lead to the formation of liquid waste, which was given the name raffinate.

These are refined aqueous solutions with high acidity caused by nitric acid, typically from 2 to 5 M, which contain americium, curium, the lanthanides, such as lanthanum, cerium, �resetin, neodymium, samarium and europium, fission products, not related to the lanthanides, such as molybdenum, zirconium, rubidium, ruthenium, rhodium, palladium and yttrium, and other metal elements, which do not belong to the lanthanide or fission products, such as iron and chromium.

Americium is the main source of residual radioactivity after 300 years of waste generated as a result of localization of these refined (more specifically through vitrification). For example, the time required for the radioactivity returned to the level of the same order as that of the radioactivity of natural uranium used to make nuclear fuel, is ten thousand years.

Selective extraction of americium present in the raffinate resulting from the implementation of the PUREX ways and COACH™ before they are sent for vitrification, would significantly reduce the heat load of vitrified waste and, thereby, the surface area available for the storage of these wastes.

In irradiated fuel after 5 years of cooling, curium 90% is in form CT-244, the half-life is 18 years. Other isotopes CT-243, CT-245, St-246, a half-life exceeding 30 years, accounting for only about 10% of the isotopes of curium. Taking into account the fact that the curium is a neutron emitter, �that makes handling difficult, and since Cm-244 in the decay leads to the formation of Pu-239 with a half-life less than 30 years, it would be preferable not to dispose directly curium with americium.

For the extraction of americium from the aqueous phase was proposed a number of ways.

More specifically, it is about the way SESAME.

This method, described in the French patent No. 2731717 [2], involves the electrochemical oxidation of americium which is stable in aqueous solution with the degree of oxidation of III - americium (VI) with, on the one hand, electrochemical mediator, whose role is to facilitate the formation of americium (VI), and, on the other hand, a complexing agent, whose role is to stabilize americium (VI) in aqueous solution. Then hexavalent americium can be selectively extracted from the aqueous phase in which it is located, the organic phase containing the extracting solvent is a substance, such as tri-n-butyl phosphate (or TBP), or acidic extracting a substance, such as bis(2-ethylhexyl)phosphoric acid (HDEHP or).

Application of the method for SESAME selective extraction of americium from the raffinate resulting from the implementation of the PUREX ways and COACH™, is not considered for the simple reason that the presence of oxidizable fission products significantly alters the efficiency of the electrochemical oxide�termination of americium and, therefore, the efficiency of the extraction of this element of the organic phase. That is why this method was proposed and to date only applied for the purification of aqueous solutions containing only americium, curium and in some cases, the lanthanides, such as those occurring as a result of the implementation of methods SANEX and DIAMEX.

In addition, the known method TALSPEAK.

This method described by B. Weaver, and F. A. Kappelmann (V. Weaver, and F. A. Kappelmann) in the report, oak ridge national laboratory Report ORNL-3559, 1964) [3], provides for the separation of americium and curium after the separation of these two elements from the lanthanides and other decay products. For this it uses the organic phase consisting of a mixture of TBP/HDEHP in aromatic solvent type toluene or diisopropylbenzene, and the aqueous phase containing a mixture of polyamino acid/hydroxycarbonic acid, the pH of which is set at 2 to 3 by adding a base.

In relation to cleaning raffinate resulting from the implementation of the PUREX method or COACH™, method TALSPEAK would reduce the acidity of this raffinate so that its pH was brought to the level that is greater than 1, with the arising of a fairly large risk of hydrolysis of the fission products present in the raffinate, which can lead to the formation of insoluble �of Reducto, containing, for example, zirconium, molybdenum or ruthenium.

In addition, in the method TALSPEAK separation of americium and curium from the fission products can only be achieved with an organic phase comprising aromatic solvent, whereas in the PUREX ways and COACH™ is used aliphatic solvent.

From this it follows that application of the method TALSPEAK after the PUREX method or COACH™ also cannot be considered.

In addition, the known method ALINA.

This method, which was described in the application for U.S. patent No. 2007/0009410, [4], involves the extraction of americium from the aqueous phase containing curium and in some cases other elements such as the lanthanides, with the use of the organic phase, consisting of a synergistic mixture of (chlorophenyl)dithiophosphinic acid/three(ethylhexyl)phosphate or (chlorophenyl)dithiophosphinic acid/oxide trialkylphosphine in ISO-octane and tert-butylbenzene. The selectivity of this compound would be sufficient for the selective extraction of americium from the aqueous phase, containing from 0.1 to 0.5 mol/l of nitric acid.

The use of this method for cleaning a raffinate resulting from the implementation of the PUREX method or COACH™, would require, as in the case of the method TALSPEAK, reduce the content of nitric acid in the raffinate to a maximum of 0.5 mol/l, to ensure sufficient �effektivnosti extraction and separation, that also leads to the risk of hydrolysis of the fission products present in the raffinate, and, consequently, the formation of insoluble products.

Furthermore, the organic phase used in the method ALINA, can largely be extracted some of the fission products, such as zirconium, molybdenum, ruthenium and palladium, resulting in a reduction of the perceiver and the extractive capacity of this phase relative to the americium and, most importantly, a significant complication of the method with subsequent attempts to retrieve one of americium in an appropriate aqueous phase.

In addition, the organic phase used in the method ALINA, includes four components, one of which leads to the formation of decomposition products containing sulfur atoms or chlorine that may be difficult to apply within the industrial way in the nuclear industry due to the possibility of formation of sulfuric or hydrochloric acid. The presence of these four components is considerably complicates the processing becomes dirty organic phase, which is" the problem has not even been investigated to date.

In addition, the known method DIAMEX 2.

This method, described in [5], involves the extraction of americium from the aqueous phase containing curium, when using an organic phase consisting of malonamide DMDOHEMA TPH in the Selectivity of this molecule would be sufficient for extraction of americium with a yield of 99% in the medium with the concentration of nitric acid, at least about 1.7 mol/l, even though 99% of curium will remain in the aqueous phase, as follows from the experiment conducted with the recovered solution in 2002. Although this method is of interest to the cleaning solution with a very high acidity, to produce an aqueous solution containing only americium and curium, it requires subsequent extraction cycles other organic solvents, which complicates the overall scheme.

Finally, the known method DIAMEX-SANEX.

This method was proposed in the French patent No. 2845616, [6] for the separation of actinides with the oxidation state III, that is, americium and curium from the lanthanides after the implementation of the PUREX method.

This method is based on the use of two of the extracting agents operating in non-overlapping chemical fields, namely: first extractive substances of the type of solvent, which is able to simultaneously extract the actinides (III) and lanthanides from aqueous phase with high acidity caused by nitric acid, and the second extraction of the substance, the type of acid that is able to extract the lanthanides from aqueous phase with low acidity, due to nitric acid.

Schematically the method comprises the co-extraction of actinides (III) and lanthanides from aqueous phase with high acidity, which they n�are gone, the organic phase containing the extracting solvent is a substance, then, after adding the acid extraction of the substance to the organic phase, extravergine actinides (III) from the organic phase acidic aqueous solution. When this acidic extracting the substance helps to keep the lanthanides in organic phase and, thus, to avoid joint extracoronary last with actinides (III).

So, during the work, the inventors found that a surprising way by using two of the extracting agents operating in non-overlapping chemical fields, can be used for selective extraction of americium from aqueous nitric acid phase containing in addition to this element and curium fission products, including the lanthanides, provided an appropriate choice of, on the one hand, the first extracting substances and, on the other hand, certain conditions in which this shall be implemented.

It is on this observation, the present invention is based.

Disclosure of invention

It is known that in the field of extraction of liquid liquid, that is, when using the difference of the solubility of the chemical elements, which must be divided between the aqueous phase and the organic phase is:

- the distribution coefficient between the two phases, organic and aqueous, Metalli�die element M, denoted by dm, corresponds to the ratio between the concentration (or activity) of this element in the organic phase and the concentration of the same element in the aqueous phase;

- the coefficient of extraction of the metal element M, denoted Eat, corresponds to the up/down*dm, i.e. the product of the relationship between the volume or volumetric flow rate (if the contacting phase circulate) the organic phase and the volume or volumetric flow rate of the water phase on the distribution coefficient dm of this element; whereas

- separation factor of two metal elements M1 and M2, denoted FSM1/M2, corresponds to DM1/DM2, i.e. the ratio of the distribution coefficient of element Ml and the coefficient of the element M2.

Thus, an object of the present invention is a method for the selective extraction of americium from the aqueous phase A1, which contains at least 0.5 mol/l nitric acid, americium, and curium fission products, including the lanthanides, but does not contain uranium, plutonium and neptunium or contains these last three elements only in trace amounts, wherein the method is characterized in that it includes at least the following steps:

a) extraction of americium and lanthanides from aqueous phase A1, the circulation of this water phase in the first countercurrent extractor with not water-miscible organic�phase, which contains the extracting solvent is a substance capable of greater extraction of americium than curium from acidic aqueous phase, and optionally acidic extracting a substance in an organic solvent;

(b) washing the organic phase obtained in step a), the circulation of this organic phase in the second counter-current extractor with the aqueous phase A2, which contains at least 0.5 mol/l of nitric acid;

c) optional additions to the organic phase obtained in step B), the acid extraction of the substance, if one is not present in this phase;

(d) selective Stripping of americium present in the organic phase obtained in step B) or in step (C), by circulating this organic phase in the third countercurrent extractor with water phase A3, the pH of which is at least equal to 1, and which contains one or more complexing agents; and

(e) Stripping of lanthanides present in the organic phase obtained in step (C), by circulating this organic phase in the fourth countercurrent extractor with water phase A4, which contains less than 1.5 mol/l of nitric acid;

and also the fact that the ratio of volumetric flow rates at which circulate the organic phase and the aqueous phase A1 in the first extractor and the ratio of the volume with�of Orosei threads in which circulate the organic phase and the aqueous phase A2 in the second extractor, is chosen so that the coefficient of extraction of americium provided in each of the stages a) and B), was higher than 1, and the coefficient of extraction of curium, provided in each of the stages a) and b) was below 1.

Thus, in the method of the invention is used in the extraction solvent, the acidic substance and extracting a substance, such as in the way DIAMEX-SANEX, but:

- on the one hand, the extracting solvent is a substance chosen from among the extracting solvent of substances which are able to be extracted from the acidic aqueous phase to a greater extent americium than curium, that is, those that the distribution coefficient of americium provided during extraction is always higher coefficient of curium, secured during the same extraction, and this occurs regardless of the conditions in which this occurs extraction, and

on the other hand, adjusting the relationship between the volumetric flow rates at which circulate organic and aqueous phase extractors allocated to stages a) and b), so that at each of these stages for americium is provided an extraction rate of above 1 and curium is provided an extraction rate of below 1,

so you can separate these two elements from each d�UGA in the above-mentioned steps a) and b),

the americium is in the organic phase, whereas curium remains in the aqueous phase.

According to the invention, the extracting solvent is a substance more specifically may be selected from among:

- maleimides such as N,N'-dimethyl-N,N'-dibutyltindilaurate (or DMDBTDMA), N,N'-dimethyl-N,N'-dioctylsulfosuccinate (or DMDOHEMA), N,N'-dimethyl-N,N'-dictionaryname (or DMDOOMA), N,N'-dimethyl-N,N'-distinguishedName (or DMDOHMA) or N,N'-dimethyl-N,N'-dibutyltindilaurate (or DMDBDDEMA);

- oxides of carbamoylphosphate, such as oxide (or MEW);

- sulphides of triisobutylene;

- carbamoylphosphate such as dihexyl-N,N-diethylcarbamoyl (or DHDECMP); and

- mixtures thereof.

More specifically, the acid extracting agent (so named because of the presence of one or more acidic functionalities) can be selected from among:

- acids containing phosphorus, such as mono - and dialkylphosphorous acid, in particular di(2-ethylhexyl)phosphoric acid (HDEHP or), di-(n-hexyl)phosphoric acid (or HDHP), di-(1,3-dimethylbutyl)phosphoric acid (or HBDMBP) or diisodecylphthalate acid (or DIDPA), mono - and dialkylphosphorous acids such as 2-ethylhexyl-2-ethylhexyl-phosphonic acid (or NINER), mono - and dialkylphosphinate acid, thiophosphamide �of islote, thiophosphonate acid and thiophosphonate acids;

- lipophilic carboxylic acids;

- sulfonic acid, such as dinonylnaphthalene sulfonic acid (or HDNNS); and

- mixtures thereof.

Regarding the organic solvent, it can be selected from among all polar or aliphatic organic solvents, which are used to implement the extraction of the liquid fluid in the treatment of irradiated nuclear fuel, such as toluene, xylene, tert-butyl-benzene, triisopropylbenzene, kerosene, linear or branched dodecanes, such as n-dodecane or hydrogenated tetrapropylene (or TPH), Isan, normal paraffin hydrocarbon (NPH), mechanicalinternational and 5,5'-[oxybis-(metalinox)]bis(1,1,2,2,3,3,4,4-octadecene).

According to the invention to the aqueous phases A1 and A2 preferably add one or more complexing agents for:

to increase the rate of separation of americium and curium, marked FSAm/cm, in the implementation of stages a) and b);

to prevent the migration of the organic phase of some fission products that do not belong to the lanthanides, but which can be extracted in the extraction solvent substance, such as, for example, palladium and zirconium;

- or to enable the combination of these two results.

This or these to�plexopathies, which should have the ability of being in the water phase with high acidity, almost with a pH of<0, to form complexes preferably with curium, rather than with americium and/or substantially to form complexes with fission products, migration in which the organic phase is undesirable, may be more particularly selected from among:

- carboxylic acids such as oxalic acid, malonic acid or metaxalona acid (also known as ketomalonate acid);

- hydroxycarbonic acids such as glycolic acid, citric acid or tartaric acid;

- polyamino acids such as N-(2-hydroxyethyl) ethylenediaminetriacetate acid (or HEDTA), nitrilotriacetate acid (or NTA) or diethylenetriaminepentaacetic acid (or DTPA);

- pyridin polycarboxylic acids, such as dipicolinic acid (or DPA, which is also known as 2,6-pyridine dicarboxylic acid);

- diglycolamine such as tetraethyleneglycol (or TEDGA), tetramethyldisilane (or TMDGA) or tetrapropylammonium (or TPDGA);

- amine, polyazines grafted with alkyl chains comprising from 1 to 8 carbon atoms, hydroxyxine, hydroxamic acids and β-diketones.

As indicated above, one or more complexing agents also Pris�stuut in the aqueous phase A3, which is used in step (d) for the selective extracoronary americium from the organic phase, obtained either as a result of step (b), if an acidic extraction substance is present in the organic phase from step (a), or, otherwise, the result of step (C).

This or these complexing agents, which should have the ability of being in the water phase with low acidity, almost with a pH≥1, to form complexes preferably with americium, rather than the lanthanides may be more particularly selected from among:

- carboxylic acids such as oxalic acid, malonic acid or metaxalona acid;

- hydroxycarbonic acids such as glycolic acid, citric acid or tartaric acid;

- polyamino acids such as HEDTA, NTA or DTPA;

- pyridin polycarboxylic acids such as DPA;

hydrophilic polypyridine;

- amine, polyazines grafted with alkyl chains comprising from 1 to 8 carbon atoms.

The aqueous phase is A4, which is used during stage (e) to extravergine of lanthanides from the organic phase, may not contain any complexing agent. In this case it will be a simple solution of nitric acid, the acidity of which preferably fits in the range of acidity for which the extracting capability.�there are organic phase is minimal in relation to the lanthanides, and the concentration of which is preferably less than 1.5 mol/liter.

However, this solution may be added one or more complexing agents of the type of carboxylic acids, hydroxycarbonic acids, polyamino acids, diglycolamine, sulfonic acids, phosphoric acids or polyazines grafted with alkyl chains comprising from 1 to 8 carbon atoms, more specifically, if it is assumed also to extragonadal from the organic phase in step (e) metal elements, such as zirconium and iron, which, although they do not belong to the lanthanide were extracted from the aqueous phase A1 phase a), and then remained in the organic phase.

According to the first embodiment of the method according to the invention the acid extraction substance is added to the organic phase after step (b).

Thus, phase a) is carried out using the organic phase, which contains only the extracting solvent substance as the extracting agent, and the method includes all the steps from a) to e).

In this case, the step (C) is preferably carried out, creating in the third extractor circulation of the organic phase, which not only contains the same extracting solvent substance, as that which is present in the organic phase used in step a), in the same concentration and in the same �organicheskoi solvent, but which additionally contains an acidic extraction substance, while this phase is added in said third extractor to organic phase resulting from stage (b).

In this case, the step (e) preferably should be an additional step involving the separation of the extracting solvent and acid extraction of a substance for subsequent re-use.

The extractive separation of the two substances can be effected by any of the procedures described in the above cited reference [6], namely:

- the Stripping of one of the two extracting substances from the organic phase;

- extractive distillation of a substance with a lower point of evaporation, if the point of evaporation extracting these two substances differ sufficiently;

- cryogenic hardening extracting substances with a higher solidification point, if the point of solidification extracting these two substances sufficiently removed from each other; or

the stratification of the mixture, i.e. the stimulation of the formation of two organic phases, which are not mixed with each other, each of which is substantially enriched in one of two extractive substances.

According to the invention the separation of the two extractive substances preferred�Stateline is the procedure leading to the removal of acidic extracting substances from the organic phase resulting from step (e), and preservation of the extracting solvent in this phase.

Indeed, because:

- on the one hand, it is desirable that the industrial implementation of the method according to the invention for cleaning raffinate were in the form of a sequence of cycles, each of which allows you to clear a certain amount of raffinate,

on the other hand, the organic phase also contains an organic solvent, and in which,

- finally, the extracting solvent substance and the solvent intended for use, starting from the first stage of the cycle,

it is desirable that they could remain in combination with each other from the beginning to the end of the loop.

This can greatly simplify operations with organic solvent compared to the separation of the two extractive substances that would lead to the preservation of the acidic extraction of substances in the organic phase, and would make mandatory the secondary branch of the acidic extraction of substances from the organic solvent and the trapping of the latter for re-dissolving it in the extracting solvent.

Selective removal of acidic extracting substances from the organic phase preferably assistantsecretary extracting this substance.

Then, after this removal of the organic phase is subjected to a treatment step, which may include, as is well known in itself, the lavage of this phase, one or more aqueous phases capable of extragonadal impurities and decomposition products which it contains, it does not extragere the extracting solvent is a substance, and one or more filtering procedures thus washed organic phase, if it contains a precipitate.

Preferably the organic phase obtained as a result of that treatment, separated into two fractions: a first fraction, which must consist only of the extracting solvent and the organic solvent intended for reuse in step (a) of the next cycle, and a second fraction, which is reextracted acidic extracting a substance for its re-use in step (C) of the next cycle.

Thus, it becomes possible to optimally limit the volume consumed in the extraction of substances, and the volume of organic waste and, thereby, reduce operating costs method.

According to a second embodiment of the method according to the invention the acid extraction substance is present in the organic phase from step (a).

Stage a) is carried out using� the organic phase, which contains both the extracting solvent, the acidic substance and extracting the substance, and the method does not include any step (C), no phase separation of the two extractive substances.

On the contrary, it preferably includes after step e) the step of treatment of the organic phase to remove impurities and degradation products that have accumulated during the previous stages, with a view to its reuse in the next cycle.

This treatment step may, as before, to include one or more washing water solutions and, optionally, one or several filtering procedures.

Although the advantage of this second embodiment is that it involves fewer treatments than in the previous version, it is found that some metal elements such as molybdenum, zirconium and iron, not extracted from the aqueous phase with high acidity of the organic phase containing only one of the extracting solvent is a substance, be extractable if this organic phase also contains acidic extracting a substance.

From this it follows that the presence of acidic organic phase in the extraction of a substance from step (a), leads to the fact that these metal elements are extracted from the aqueous phase A1 during this stage and �they remain in the organic phase during stage (b).

Furthermore, according to this second embodiment of the method preferably includes the additional step involving selective extravergine from the organic phase of molybdenum, for example, by means of the aqueous phase with low acidity, i.e. typically with pH 3, containing a complexing agent capable of selectively form complexes with molybdenum, such as citric acid.

This extra step is preferably carried out between step b) and step (d), in this case, the step (C) is not used.

As mentioned above, zirconium and iron can be extracoronary from the organic phase in step (e) together with the lanthanides by adding to the aqueous phase A4 one or more reasonably selected complexing agents.

According to the invention is preferably used:

- malonamic, such as DMDOHEMA, as the extracting solvent because of the pronounced ability of extractive substances of this type be extracted to a greater extent americium than curium, from the aqueous phase with high acidity caused by nitric acid;

acid containing phosphorus as an acidic extraction of a substance and, more specifically, dialkylphosphorous acid, such as HDHP or HDEHP, especially if acidic extraction substance is present in organic�coy phase, starting with step a); indeed, while extracting a substance of this type is able to play the role of a modifier phase and significantly increase the acid number of phase A1, which may occur stratification (i.e. the appearance of a third phase, which is the result of saturation of the organic phase metallic materials), and therefore, the capacity of the organic phase; and

- aliphatic solvent as the organic solvent, and more particularly, TPH, which is the solvent used in the PUREX method, currently implemented at the plants for the reprocessing of irradiated nuclear fuel.

In addition, it is preferable that the aqueous phase A1 contained nitric acid in a concentration of from 2 to 6 mol/l and contain one or more complexing agents, which are preferably selected from among hydroxycarbonic acids, polyamino acids and diglycolamine, with a particularly preferred use of hydrophilic diglycolamine, such as TEDGA.

Indeed, due to the fact that they are in a nitric acid aqueous phase is associated curium in the complexes to a far greater extent than americium, hydrophilic diglycolamine significantly increase the rate of separation of americium and curium, FSAm/Cm/in step a). Moreover, they also allow to increase the odds div�tion of americium and heavy lanthanides, such as samarium, europium and gadolinium, americium and yttrium and americium, and zirconium.

Preferably diglycolate present in the aqueous phase A1, combined with a polyamino acid such as HEDTA or DTPA, which enables to inhibit the extraction of palladium in organic phase.

However, the aqueous phase A1 may also contain, as a complexing agent and a carboxylic acid, such as oxalic acid, which enables to inhibit the extraction of molybdenum, zirconium and iron, if the organic phase does not contain dialkylphosphorous acid from step (a).

As the aqueous phase A2 preferably using a solution containing nitric acid in a concentration of from 2 to 6 mol/l and preferably containing one or more of the same complexing agents who were present in the aqueous phase A1, in the same concentration ranges.

The aqueous phase preferably A3 is a solution containing polyamino acid, such as HEDTA or DTPA, as well as carbon fiber or hydroxycarbonate acid, such as glycolic acid, is able to simultaneously play the role of a complexing agent and a buffer, the pH of which is from 2 to 4 by adding bases hydroxide, such as caustic soda, carbonate such as sodium carbonate or ti�and amine or hydroxylamine.

With respect to the aqueous phase A4 preferably using a solution containing from 0.5 to 1.5 mol/l of nitric acid and dipicolinic, such as TEDGA, alone or in combination with carboxylic acid such as oxalic acid.

According to the invention the ratio between the flow rates of streams in which circulate the organic phase and the aqueous phase A1 in the first extractor and the ratio between the flow rates of streams in which circulate the organic phase and the aqueous phase A2 in the second extractor, preferably selected so that the coefficient of extraction of americium provided in each of the stages a) and b), was higher than or equal to 1.40, and the coefficient of extraction of curium, provided in each of the stages a) and B), is lower than or equal to 0.90.

You can also reduce the number of stages present in the extractors, which carry out the steps a) and b), to obtain a satisfactory separation of americium and curium in the course of these stages.

The method of the invention has several advantages. More specifically:

- it allows you to extract americium from nitric acid aqueous phase from the extraction ratio is at least equal to 99,90% and 99.95% of the time;

- he uses no reaction of oxidation-recovery of americium or any other metallic element and, therefore, does not have the disadvantages associated with this reactie�;

- organic phase, in which it is used, has no component that can lead to the formation of chlorinated degradation products that may be difficult to work in the nuclear industry;

- the organic phase may contain aliphatic solvent; and

- it can be applied to the purification of aqueous phases with increased acidity caused by nitric acid, without the need to reduce the acidity of these phases.

Considering all these reasons, it is of special interest for the purification of americium refined, resulting from the implementation of methods for the extraction and purification of uranium and plutonium, such as the PUREX ways and COACH™.

Other features and advantages of the method of the invention will become apparent from the examples below, examples of the implementation of this method and giving reference to the attached figures.

Of course, these examples are illustrative only of the invention and in no case should not be construed as a limitation of this object.

Brief description of the drawings

Fig.1 is a schematic diagram of a first illustrative embodiment of the method of the invention.

Fig.2 is a schematic diagram of a second illustrative embodiment of sposibo the invention.

In illustrative embodiments, is shown in Fig.1 and 2, all the operations of extraction, washing, Stripping and Stripping is performed in a multi-stage type extractors mixers - decanters, pulsed columns or centrifugal extractors.

The organic phase flows entering or emerging from these devices, symbolically indicated by the solid double line, while the ow of the water phase, the incoming and outgoing of the mentioned devices, symbolically indicated by the solid single line.

The implementation of the invention

Example 1. A detailed description of the first embodiment of the method according to the invention

Fig.1 schematically shows a first embodiment of the method according to the invention, designed for cleaning in industrial scale raffinate obtained after the first cleaning cycle of the PUREX method or COACH™, for the purpose of selective extraction of americium present in the raffinate.

This raffinate, referred to below and in Fig.1 the aqueous phase A1, consists of an aqueous solution of high acidity caused by nitric acid, which contains americium, curium, and lanthanides (La, CE, Pr, Nd, Sm, Eu, Gd,...), the fission products that are not related to the lanthanides (Mo, Zr, Ru, Rd, Pa, Y,...), and other metal elements, which are neither lanthanides, no fission products, such as jelly�about and chrome.

At the same time, it does not contain uranium, plutonium and neptunium, or, if any of these elements is still present, it is found only in trace amounts, that is, its mass percentage is less than about 0.30%.

In this first example, the method is carried out in the form of a sequence of cycles, each of which includes eight of the following stages:

1) extraction of americium and lanthanides present in the aqueous phase A1, the organic phase containing the extracting substances only extracting solvent substance;

2) washing the organic phase resulting from the extraction;

3) adding an acidic extraction of the substance to the organic phase obtained after the washing;

4) selective Stripping of americium from the organic phase, enriched, thus, the acid extracting agent;

5) re-extraction of lanthanides present in the organic phase obtained after Stripping of americium;

6) reextraction acidic extracting substances from the organic phase obtained after Stripping of lanthanides;

7) purification of the organic phase, now containing as the extracting substances only extracting solvent substance; and

8) reextraction acidic extraction of substances in �raccio thus purified organic phase.

In the first stage (referred to as "Extraction of Am+Ln" in Fig.1), circulate the water phase in the first countercurrent extractor with not miscible with water, the organic phase, which contains the extracting solvent is a substance capable of greater extraction of americium than curium, from concentrated nitric acid medium in an organic solvent.

This is the extracting solvent, the substance is preferably malonamide, type DMDOHEMA, which is usually used at a concentration of from 0.5 to 0.7 mol/l, for example, of 0.65 mol/l.

Organic solvent is TRN.

Before or during the introduction of the aqueous phase A1 in the first extractor its acidity caused by nitric acid, in some cases adjusted so that it is preferably ranged from 3 to 5 mol/l, for example, a 4 mol/l.

In addition, in the aqueous phase A1 add two complexing agent, namely, polyamino acid, type HEDTA, usually at a concentration of from 0.01 to 0.1 mol/l, and oxalic acids, typically at a concentration of from 0.01 to 0.5 mol/liter.

At the second stage (referred to as "Washing" in Fig.1), circulate the organic phase obtained after the first extractor, the second counter-current extractor with the aqueous phase A2, typically containing from 2 to 3 mol/l nitric acid, for example, a 2.4 mol/l, and those �e complexing agents in the same range of concentrations, that and the aqueous phase A1.

Choosing properly the relationship between the volumetric flow rates at which circulate the organic and aqueous phases in each of the extractors: the first and second, and the number of steps in these extractors (see example 3), thus, as a result of the second stage receives the organic phase, in which all, or nearly all americium, part of cerium and praseodymium and a very small amount of lanthanum, samarium and neodymium, and the aqueous phase, which is all, or nearly all curium, the rest of cerium, praseodymium, lanthanum, samarium and neodymium, as well as all other metal elements that were present in the aqueous phase A1.

The aqueous phase obtained as a result of this second phase, is withdrawn to the first extractor, where it connects with the aqueous phase A1 and added to it, whereas the organic phase is withdrawn to the third extractor, which are simultaneously the third stage and the fourth stage (having the name "Reextraction Am" in Fig.1).

In the third extractor, the organic phase is:

- on the one hand complement the organic phase of the same composition as that of the organic phase used for the implementation of the first phase, but which also contains acidic extraction substance type HDHP, usually at a concentration of from 0.1 to 0.5 mol/l, for example, order� of 0.3 mol/l; and

on the other hand, circulate the organic phase with a counter-current aqueous phase A3 for selective Stripping of americium.

This aqueous phase contains a polyamino acid, a type of DTPA, usually at a concentration of from 0.01 to 0.1 mol/l, and carbon or hydroxycarbonate acid, type of glycolic acid, is able to simultaneously play the role of a complexing agent and a buffer, usually at a concentration of from 0.1 to 1 mol/L.

Preferably the pH is set at 2 to 4, for example, 3, by adding a base, such as soda.

As a result, the aqueous phase, which contains, as a metal element only americium, and the organic phase, which contains cerium, praseodymium, lanthanum, samarium and neodymium, which were partially extracted during the first phase.

At the fifth stage (having the name "Reextraction Ln" in Fig.1), circulate the organic phase in the fourth countercurrent extractor with water phase A4, which generally contains from 0.5 to 1 mol/l nitric acid and optional diglycolate, usually at a concentration of from 0.01 to 0.5 mol/liter.

So, as a result of the fifth stage get the organic phase, which no longer contains any of the metal elements, which it was loaded during the first phase, but which contents�t in addition to the extracting solvent and acid extraction of a substance a certain amount of impurities and degradation products, more specifically radiolysis that have accumulated during the previous stages.

At the sixth stage (having the name "Reextraction HDHP" in Fig.1), circulate the organic phase in the fifth countercurrent extractor with an aqueous solution with a pH above 7, for example, a hydroxide, such as caustic soda, carbonate such as sodium carbonate, amine or hydroxylamine.

Then on the seventh stage (which has the name of "Cleaning DMDOHEMA+THREE" in Fig.1) circulate the organic phase, thus freed from the HDHP, in the sixth with a counter-current extractor aqueous solution of strong bases or the salts of strong bases with a pH at least equal to 8, such as a soda solution or sodium carbonate, and in some cases carry out one or several filtering procedures, if the organic phase contains a precipitate.

At the eighth stage (having the name "Reextraction HDHP" in Fig.1) thus purified organic phase is divided into two fractions: the first fraction is 75 to 95% (by volume) of this phase and the second fraction is from 5 to 25% (by volume) of the said phase, and which is reextracted HDHP.

This Stripping, for example, can be carried out by acidification of the basic aqueous solution used for the extraction HDHP from the organic phase, by adding a solution of 4 - 5 M nitric acid, and about�by ensuring the circulation of this solution acidified in the seventh with a counter-current extractor fraction of the organic phase, you want to extragonadal is extracting a substance.

Thus catch the organic phase in the form of two fractions, one of which contains only DMDOHEMA in TPH, and the other of which contains both DMDOHEMA and HDHP in TPH.

Now these fractions can be re-used, respectively, in the first phase and the third phase of the next cycle.

Example 2. A detailed description of the second embodiment of the method according to the invention

Fig.2 schematically shows a second embodiment of the method according to the invention, also designed for cleaning in industrial scale raffinate obtained after the first cleaning cycle of the PUREX method or COACH™, for the purpose of selective extraction of americium present in the raffinate, but in which the acidic extraction substance is present in the organic phase at all stages of the method.

In this second example, each cycle of the method includes the following six stages:

1) extraction of americium and lanthanides present in the aqueous phase A1, the organic phase containing simultaneously extracting solvent, the acidic substance and the extracting agent;

2) washing the organic phase resulting from the extraction;

3) selective Stripping of molybdenum from the organic phase obtained as a result of premiani�;

4) selective Stripping of americium from the organic phase, thus freed from molybdenum;

5) re-extraction of lanthanides present in the organic phase obtained after Stripping of americium; and

6) purification of the organic phase.

In the first stage (referred to as "Extraction of Am+Ln" in Fig.2), circulate the water phase in the first countercurrent extractor with the organic phase containing simultaneously extracting solvent, the acidic substance and extracting the substance in TPH.

The extracting solvent substance is DMDOHEMA, as in example 1, which is also usually used at a concentration of from 0.5 to 0.7 mol/l, for example 0.6 mol/l, whereas the acidic extraction substance is HDEHP, which is usually used at a concentration of from 0.1 to 0.5 mol/l, for example, of 0.3 mol/l.

As in example 1, due to nitric acid, the acidity of the aqueous phase A1 in some cases adjusted before or during its introduction in the first extractor so that it is preferably ranged from 2 to 6 mol/l, for example, a 4 mol/l.

In addition, it added two complexing agent, namely, HEDTA, as in example 1, but here with a higher concentration, typically 0.05 mol/l, and diglycolamine type TEDGA usually at a concentration of from 0.01 to 0.5 mol/l, for example, 0.05 mol/l.

At the second stage (having name�s "Flushing" in Fig.2), circulate the organic phase obtained after the first extractor, the second counter-current extractor with the aqueous phase A2, usually containing from 4 to 6 mol/l of nitric acid, for example, 5 mol/l, and the same complexing agents within the same ranges of concentrations, and the aqueous phase A1.

Choosing appropriately the ratio between the flow rates of streams in which circulate the organic and aqueous phases in each of the extractors: the first and second, and the number of steps in these extractors (see example 3), thus, as a result of the second stage receives the organic phase, in which all, or nearly all americium, cerium, lanthanum, praseodymium, neodymium, molybdenum, and iron, and a very small amount of zirconium, and the aqueous phase, which contains the rest of Zirconia and all or almost all other metallic elements, that are present in the aqueous phase A1, including curium.

The aqueous phase obtained as a result of this second phase, is withdrawn to the first extractor, where it connects with the aqueous phase A1 and added to it, whereas the organic phase is withdrawn to the third extractor, in which the third stage (having the name "Reextraction Mo" in Fig.2).

For this circulate mentioned organic phase in the third extractor with protiviti�ω aqueous solution, containing the complexing agent, the type of citric acid, typically at a concentration of from 0.1 to 1 mol/l, pH of which is set at 2 to 4, for example 3, by adding a base, such as soda.

Thus, as a result of the third stage receives the aqueous phase containing molybdenum, and the organic phase is freed from this element.

In the fourth stage (having the name "Reextraction Am" in Fig.2), circulate the organic phase in the fourth countercurrent extractor with water phase A3, which contains polyamino acid type HEDTA, usually at a concentration of from 0.01 to 0.5 mol/l, and carbon or hydroxycarbonate acid, type of glycolic acid, is able to simultaneously play the role of a complexing agent and a buffer, usually at a concentration of from 0.1 to 1 mol/l, and the pH of which is preferably set at 2 to 4, for example, 3, by adding a base, such as soda.

So, as a result of the fourth stage receive the aqueous phase, in which the number of metal elements contained only americium, and the organic phase, which contains cerium, lanthanum, praseodymium, neodymium and iron, provided that the molybdenum was extrahieren during the third stage.

At the fifth stage (having the name "Reextraction Ln" in Fig.2) circulate about this�egy for organic phase in the fifth with a counter-current extractor aqueous phase A4, usually contains from 0.5 to 1 mol/l nitric acid and two complexing agent, namely diglycolate type TEDGA, which is usually used at a concentration of from 0.01 to 0.5 mol/l and not necessarily that of oxalic acid, which is usually used at a concentration of from 0.01 to 0.8 mol/liter.

So, as a result of the fifth stage get the organic phase, which no longer contains any of the metal elements, which it was loaded during the first phase, but which contains in addition to the extracting solvent and acid extraction of a substance a certain amount of impurities and degradation products, more specifically radiolysis that have accumulated during the previous stages.

At the sixth stage (which has the name of "Cleaning DMDOHEMA+HDEHP+TRN" in Fig.2) this organic phase is purified in the same manner as in example 1.

Now thus purified organic phase can be reused in the first phase of the next cycle.

Example 3. Confirmation of examples 1 and 2

The following material shows the values of the distribution coefficients of metal elements received:

for americium and curium by calculation of the ratio of the activity of these elements in this organic phase activity to the same elements in the aqueous phase after bringing it into contact with this �organicheskoi phase;

- in relation to the other metal elements by calculating the difference between the initial and final concentrations of these elements in this aqueous phase and the ratio between this difference and the initial concentration of the same elements in the same aqueous phase.

All measurements of the activity of americium and curium were performed alpha spectrometry, whereas all measurements the concentrations of the other metal elements were performed by atomic-emission spectrometry with inductively coupled plasma, also known by the acronym ICP-AES.

1) confirmation of the first example of implementation:

Extraction of americium and lanthanides/washed organic phase:

These stages were confirmed by tests in the pipe, supplemented by calculations based on the results obtained in these tests. Tests in the pipe were carried out using:

as organic phase: phase consisting of 0.65 mol/l DMDOHEMA in TPH;

as the aqueous phase A1: solution simulating raffinate obtained by purification of the PUREX method of irradiated nuclear fuel type UOX3 (excluding curium, which was present only in trace amounts), to which was added 0.01 mol/l oxalic acid and 0.01 mol/l HEDTA; and

as the aqueous phase A2: solution acidity due to nitrogen Ki�LOTOS, equal to 2.4 M, and containing 0.01 mol/l oxalic acid and 0.01 mol/l HEDTA.

Due to nitric acid, the acidity of the aqueous phase A1 was 4.2 mol/l, and its qualitative and quantitative composition of the metal elements is presented in table I below. All the elements were dissolved in nitrate form.

Table I
Concentration
mmMG/L
Am0,73170
Cm1,4·10-53,4·10-3
Y1,7150
La2,9410
CEthe 5.7790
Pr2,6370
Nd9,41360
Sm1,8 270
Eu0,3452
Gd0,3250
Pd5,0530
Zr131190
Mo121130
Fe1,8100

The organic phase, pre-balanced by the acid by the addition of 3M nitric acid was brought into contact with the aqueous phase A1 rate of 1.3 per volume of the aqueous phase A1 to 1 volume of organic phase and aqueous phase A2 rate of 3.1 per volume of the aqueous phase A2 1 volume of organic phase, and the phase of the left under stirring for 10 minutes at a constant temperature of 25°C.

After decantation and separation of the aqueous and organic phases was measured activity of americium and curium in each of these phases, whereas the concentration of other metal elements were measured only in the aqueous phase.

Then the organic phase was brought into contact with the aqueous phase A2 rate of one volume of the organic phase 3.1 volume of the aqueous phase, and both phases of�left under stirring for 10 minutes at a constant temperature of 25°C.

And in this case, after decantation and separation of these phases was also measured activity of americium and curium in each of them, whereas the concentration of other metal elements were measured only in the aqueous phase.

In table II below shows the distribution coefficients (DMthe extraction coefficients Eat and partition coefficients FSAm/Mobtained on the basis of such measurements of activity and concentration.

Y
Table II
ExtractionWashing
DMEMFSAm/MDMEMFSAm/M
Am6,21,4314,51,441
Cm4,10,941,52,80,901,6
1,20,28the 5.20,90,295,0
La3,60,831,72,60,831,7
Cethe 4.71,081,33,41,091,3
Pr4,30,991,43,10,991,5
Nd3,60,831,72,60,831,7
Sm4,10,941,52,90,931,6
Eu3,3 1,92,40,771,9
Gd2,20.512,91,60,512,8
Pd0,80,187,70,60,197,5
Zr0,40,0914,00,30,1015
Mo0,90,21the 6.60,60,197,5
Fe2,10,482,91,50,483,0

Calculations carried out on the basis of the distribution coefficients and coefficients extraction presented in this table show that on an industrial scale can be achieved very good separation of these elements, applying extractors having a sufficient number of steps.

For example, the scheme, which provided for the application:

- extractor with 24 steps for phase extraction in combination with extractor with 24 steps to a washing step;

- the same acidity as in the tests in the pipe;

the same extractive substances (DMDOHEMA) and complexing agents (HEDTA+oxalic acid) as those that were used in the tests in the pipe, and at the same concentrations; and

- relationship of volumetric flow rates And proportional relationship of the volumes used in the tests in the pipe, namely relations of volumetric flow rates And right - of 0.23 for the extraction step and 0.32 for stage wash;

leads to the distributions given in table III below.

Table III
The aqueous phase obtained after extractionThe organic phase obtained after washing
Am0,05%99,95%
Cm99,80%0,20%
Y100% 0%
La99,55%0,45%
CE22,16%77,84%
Pr70,64%29,36%

The aqueous phase obtained after extractionThe organic phase obtained after washing
NdRUB 99.56%0,44%
Smof 99.11%0,89%
Eu100%0%
Gd100%0%
Pd100%0%
Zr100%0%
Mo100%0%
Fe100%0%

So, americium is present � organic phase, the resulting washing, more than 99, 95%, along with approximately 78% of cerium, 29% of praseodymium, but only 0.2% of curium and 0.4-0.9% of lanthanum, neodymium and samarium. Other fission products remain in the aqueous phase.

- Re-extraction of americium:

This phase was confirmed by tests in the tube, which were performed using:

- organic phase, simulating the organic phase, which would be obtained using the described design scheme, and contains, therefore, 0.4 mol/l of nitric acid, americium, lanthanum, cerium, praseodymium, neodymium and samarium, and to which was added with 0.15 mol/l HDHP; and

as the aqueous phase A3: a solution containing 0.05 mol/l DTPA and 1 mol/l glycolic acid, the pH of which was adjusted to 3 by the addition of soda.

These two phases are brought into contact with each other, one to one by volume, 1/25 volume of the aqueous phase occurred by adding a small amount of HUME soda. The purpose of adding this small amount of soda was due to partial neutralization of nitric acid acidity of the organic phase so that after bringing the two phases into contact pH of the aqueous phase A3 could remain at a level close to 3 and, consequently, in the field of acidity where the system DTPA/glycolic acid selectively binds to complexes of americium.

The organic and aqueous phases were left under stirring for 10 minutes at a constant temperature of 25°C. Then, after decantation and separation of these phases was measured activity of americium in each of them, whereas the concentration of other metal elements were measured only in the aqueous phase.

Table IV below shows the distribution coefficients of dm, and the partition coefficients of REE/Al obtained on the basis of such measurements of activity and concentration.

Table IV
dmFSM/Am
Am0,061
La21350
CE13217
Pr467
Nd1,728
Sm1,932

The obtained distribution coefficients are quite satisfactory, as they have allowed �s to provide on an industrial scale, the Stripping of americium in the preservation of lanthanides in organic phase, when using the ratio of volumetric flow rates And about 2.

In addition, all sharing ratio exceeds 20, which is sufficient to ensure separation of americium and lanthanides using an extractor that has a limited number of steps, for example, 16 steps.

- Re-extraction of lanthanides:

This phase was confirmed by tests in the tube, which were performed using:

- organic phase, which was obtained as a result of testing in the pipe relating to the Stripping of americium; and

as the aqueous phase A4: either 1M aqueous solution of nitric acid or a solution of 0.5 M nitric acid containing 0.2 mol/l TEDGA.

These two phases are brought into contact with each other, one to one by volume, and left under stirring for 10 minutes at a constant temperature of 25°C.

Then, after decantation and separation of these phases was measured concentration of lanthanum, cerium, praseodymium, neodymium and samarium only in the aqueous phase.

In table V below presents for each type of the aqueous phase A4 distribution coefficients of dm, obtained on the basis of the thus measured concentration.

Table V
The lanthanidesdm A4-HNO31MFSM/AMA=HNO30.5 M+TEDGA 0.2 M
La0,40,06
CE0,60,03
RG0,60,02
Nd0,60,01
Sm0,60,01

These distribution coefficients are quite satisfactory, since they would provide on an industrial scale quantitative Stripping of lanthanides using extractor having at most 8 steps, and the relationship of volumetric flow rates of the organic and aqueous phases of 0.5 or 6.5 depending on what is used, aqueous phase: aqueous solution of 1M nitric acid or a solution of 0.5 M nitric acid containing 0.2 mol/l TEDGA. The utilization of the phase of the second type is to significantly reduce the amount of the produced water stream.

2) Confirmation of the second example of implementation:

Extraction of americium and lanthanides/washed organic phase:

This phase was confirmed by tests in the pipe based on the results obtained in these tests. Tests in t�ube were performed using:

as organic phase: phase consisting of 0.6 mol/l DMDOHEMA and 0.3 mol/l HDEHP in THREE;

as the aqueous phase A1: solution acidity, due to nitric acid equal to 4M, identical qualitative and quantitative composition of the solution, presented in table I above, to which was added 0.05 mol/l TEDGA and 0.05 mol/l HEDTA; and

as the aqueous phase A2: solution acidity, due to nitric acid equal to 5M, and containing 0.07 mole/liter TEDGA and 0.05 mol/l HEDTA.

The organic phase, pre-balanced by the acid by addition of 4M nitric acid was brought into contact with the aqueous phase A1 at the rate of one to one by volume, and phase left under stirring for 10 minutes at a constant temperature of 25°C.

After decantation and separation of the aqueous and organic phases was measured activity of americium and curium in each of these phases, whereas the concentration of other metal elements were measured only in the aqueous phase.

Then the organic phase was brought into contact with the aqueous phase A2 at a rate of one to one by volume, and these phases have left under stirring for 10 minutes at a constant temperature of 25°C.

And in this case, after decantation and separation of the organic and aqueous phases was also measured activity of americium and curium in each of these phases, whereas conc�Tracey other metal elements were measured only in the aqueous phase.

In table VI below shows the distribution coefficients of dm, the coefficients extraction Eat and partition coefficients FSAm/m, obtained on the basis of such measurements of activity and concentration.

Table VI
ExtractionWashing
DMEMFSAm/MDMEMFSAm/M
Am3,41,410,521,61
Cm1,90,761,80,210,632,5
Y0,140,056240,010,0352
La3,41.411,13,30,5
CE4,01,60,90,92,70,6
Pr3,71,50,90,72,10,7
Nd3,11,31,10,361,11,4
Sm1,00,43,40,130,394
Eu0,960,383,50,050,1510
Gd0,560,23/td> 6,10,020,0626
Pd0,050,02680,10,3the 5.2
Zr0,0240,0091421,9the 5.70,3
Mo46180,126780
Fe59240,0610300,1

In the absence of TEDGA in the aqueous phase A1, the partition coefficients of americium and other metal elements similar to those shown in table II above, because the high acidity caused by nitric acid, DMDOHEMA is the predominant substance for extracting americium, curium and lanthanides (III). HDEHP is predominant for �straccia molybdenum, zirconium and iron, and plays the role of a modifier phase, allowing DMDOHEMA to extract more cations than in the case when it is used separately.

In the presence of TEDGA it was noted that the partition coefficients have changed. The partition coefficients of americium and curium, heavy lanthanides (Sm, Eu, Gd), yttrium and zirconium increased. In contrast, the partition coefficients of americium and light lanthanides (La, CE, Pr, Nd) remain low only in the absence of TEDGA. This means that TEDGA allows you to not only increase the coefficient of separation of americium and curium, but also the coefficients of the separation of lanthanides with neighboring atomic numbers.

Comparison of the results obtained, respectively, for the extraction and washing, shows that using a larger amount of TEDGA allows you to increase the coefficient of separation of americium and curium. Thus, the transition from the content of TEDGA in 0.05 M (column "extraction") to the contents of TEDGA 0.07 M (column "flushing"), separation factor FSAm/Cmincreased by 40%. In addition, the separation factor FSAm/Cmmore than doubled, while the separation factor FSAm/Cmhas been reduced by half.

These results show that, due to TEDGA, the behavior of a smaller number of lanthanides approaches the behavior of americium, which reduces the risk of accumulation of these elements under the action of reek�traction during stage washing and Stripping during the extraction step.

In addition, the increase in the separation factor FSAm/Cmsuggests reducing the number of steps required for the extraction of americium and washing of the organic phase resulting from the extraction, compared to the number of steps required for carrying out the same operations in the absence of TEDGA. Indeed, the separation factor FSAm/Cmchanged from 1.6 (table II) to 2.5 (table VI), reduces the number of steps in half.

So, these calculations are performed on the basis of the distribution coefficients and partition coefficients in table VI above, show that the scheme provides for the application:

- extractor with 15 steps for extraction in combination with apparatus 12 steps for washing;

- the same acidity as in the tests in the pipe;

- extracting the same substances (DMDOHEMA+HDEHP) and complexing agents (TEDGA+HEDTA), as those that were used in the tests in the pipe, and at the same concentrations; and

- relationship of volumetric flow rates And for the extraction of 0.4 and 3 for washing;

leads to the distributions shown in table VII below.

Table VII
Water� phase, obtained after extractionThe organic phase obtained after washing
Am0,05%99,95%
Cm99,92%0,07%
Y100%0%
La0,01%99,99%
CE0,01%99,99%
Pr0%100%
Nd0,10%99,90%
Sm99.97% of0,02%
Eu99,99%0,01%
Gd100%0%
Pd100%0%
Zr99,20%0,80%
Mo0% 100%
Fe0%100%

So, americium is present in the organic phase obtained as a result of flushing, in the amount of more than 99.95%, along with approximately 100% of lanthanum, cerium, praseodymium, neodymium, molybdenum and iron, but only 0.07 percent of curium and 0.8% zirconium. Other fission products remain in the aqueous phase resulting from the extraction.

- Stripping of molybdenum:

This phase was confirmed by tests in the tube, which were performed using:

- organic phase, simulating the organic phase, which would be obtained using the described design scheme, and contains, therefore, of 0.33 mol/l nitric acid and americium, lanthanum, cerium, praseodymium, neodymium, zirconium, molybdenum, and iron; and

as the water phase: solution containing 0.2 mol/l citric acid, pH of which was adjusted to 3 by the addition of soda.

These two phases are brought into contact with each other, one to one by volume, with 1/30 of the volume of the aqueous phase occurred by adding a small amount of 10M soda intended for partial neutralization of nitric acid, the organic phase.

The organic and aqueous phases were left under stirring for 10 minutes at a constant temperature of 25°C. Then, after decanter�and and separation of these phases was measured activity of americium in each of them, whereas the concentration of other metal elements were measured only in the aqueous phase.

In table VIII below shows the distribution coefficients (DMand the partition coefficients P8 m/mo>obtained on the basis of such measurements of activity and concentration.

Table VIII
DMFSM/Mo
Am199-102
La402-103
CE472-103
RG673-103
Nd603-103
Zr5132-104
Mo0,021
Fe157-102

As shown by this table�and, the distribution coefficients of metal elements other than molybdenum, above 1, and the partition coefficients of these elements and molybdenum above 700.

Thus, it is possible to plan implementation on an industrial scale selective Stripping of molybdenum extractor that has a limited number of steps, for example, 8 degrees, and with using the ratio of volumetric flow rates Of from 1 to 10 so as to form the water flow a small amount.

- Re-extraction of americium:

This phase was confirmed by tests in the tube, which were performed using:

- organic phase, which was obtained as a result of testing in the pipe relating to the Stripping of molybdenum; and

as the aqueous phase A3: solution containing 0.05 mol/l HEDTA and 1 mol/l glycolic acid, the pH of which was adjusted to 3 by the addition of soda.

These two phases are brought into contact with each other, one to one by volume, and left under stirring for 10 minutes at a constant temperature of 25°C. Then, after decantation and separation of these phases was measured activity of americium in each of them, whereas the concentration of other metal elements was measured only in the aqueous phase.

In table IX below shows the distribution coefficients (DMand the partition coefficients FS/Am obtained on the basis of such measurements of activity and concentration.

Table IX
DMFSM/Am
Am0,131
La8,263
CE5,139
RG2,620
Nd1,612
Zr105807
Fe1186

As this table shows, the distribution coefficients of all the metal elements different from americium, above 1, and the partition coefficients of these elements and americium above 9.

Thus, it is possible to plan implementation on an industrial scale Stripping of americium extractor having a number of stages of order 16, and when using the volumetric relationship soon�TEI threads About/A of 0.5 to 2.

- Re-extraction of lanthanides:

This phase was confirmed by tests in the tube, which were performed using:

- organic phase, which was obtained as a result of testing in the pipe relating to the Stripping of americium; and

as the aqueous phase A4: solution acidity, due to nitric acid equal to 1M, containing 0.2 mol/l TEDGA and 0.8 mol/l oxalic acid.

These two phases are brought into contact with each other, one to one by volume, and left under stirring for 10 minutes at a constant temperature of 25°C. Then, after decantation and separation of these phases was measured concentration of the different metal elements only in the aqueous phase.

In table X below shows the distribution coefficients (DMobtained on the basis of these measurements the concentration.

Table X
dm
La0,003
CE0,001
RG0,001
Nd0,001
Zr0,002
Fe0,015

The obtained distribution coefficients are quite satisfactory, since they would provide on an industrial scale quantitative Stripping of lanthanides, iron and zirconium in applying the extractor having about 4 steps and when the ratio of the volumetric velocity Of the order of 0.1.

Cited references

[1] the international application WO 2007/135178

[2] French patent No. 2 731 717

[3] V. Weaver et F. A. Kappelmann, Rapport ORNL-3559, 1964

[4] Application for U.S. patent No. 2007/0009410

[5] R. Baron, M. Lecomte, B. Boullis et D. Warin, " Separation of the Long Lived Radionuclides: Current Status and Future R&D Program in France ", Proceedings of Global 2003, New Orleans, Louisiana, November 2003, p.508-511.

[6] French patent No. 2845616

1. Method for the selective extraction of americium from the aqueous phase A1, which contains at least 0.5 mol/l nitric acid, americium, and curium fission products, including the lanthanides, and optionally contains uranium, plutonium and neptunium in trace amounts, characterized by the fact that it includes at least the following stages:
(a) extraction of americium and lanthanides from aqueous phase A1 through this circulation of the water phase in the first countercurrent extractor with not miscible with water, the organic phase, which contains the extracting solvent substance, which can be extracted from the acidic aqueous phase to a greater degree�Yeni americium, than curium, and, optionally, an acidic extracting a substance in an organic solvent;
(b) washing the organic phase obtained in step (a), by circulating this organic phase in the second counter-current extractor with the aqueous phase A2, which contains at least 0.5 mol/l of nitric acid;
c) optionally, adding to the organic phase obtained in step b), the acid extraction of the substance, if it was not present in the used organic phase at the stage a);
(d) selective Stripping of americium present in the organic phase obtained in step b) or step c), by circulating this organic phase in the third countercurrent extractor with water phase A3, pH which is at least equal to 1, and which contains one or more complexing agents; and
(e) re-extraction of lanthanides present in the organic phase obtained in step c), by circulating this organic phase in the fourth countercurrent extractor with water phase A4, which contains less than 1.5 mol/l of nitric acid;
and the fact that the ratio between the flow rates of streams in which circulate the organic phase and the aqueous phase A1 in the first extractor and the ratio between the flow rates of streams in which circulate the organic phase and the aqueous phase A2 in the second extractor, so choose, Thu�would coefficient extraction of americium in each of the stages a) and b) was above 1 and the coefficient of extraction of curium in each of the stages a) and b) was below 1.

2. A method according to claim 1, wherein the extracting solvent is a substance selected from malonamides, oxides of carbamoylphosphate, sulphides of triisobutylene, carbamoylphosphate and mixtures thereof.

3. A method according to claim 2, wherein the extracting solvent substance is malonamide and preferably N,N'-dimethyl-N,N'-dioctylsulfosuccinate.

4. A method according to any one of claims. 1-3, in which acidic extracting a substance selected from mono - and dialkylphosphorous acids, mono - and dialkylphosphorous acids, mono - and dialkylphosphinate acids, thiophosphonic acids, thiophosphonic acids, thiophosphonic acids, lipophilic carboxylic acids, sulfonic acids and mixtures thereof.

5. A method according to claim 4, wherein the acidic extraction substance is dialkylphosphinate acid, preferably di-(n-hexyl)phosphoric acid or di-(2-ethylhexyl)phosphoric acid.

6. A method according to any one of claims. 1-3, in which the organic solvent is an aliphatic solvent and preferably hydrogenated tetrapropylene.

7. A method according to any one of claims. 1-3, in which the aqueous phase A1 contains nitric acid in a concentration of from 2 to 6 mol/liter.

8. A method according to any one of claims. 1-3, in which the aqueous phase A1 contains one or more complexing agents selected from hydroxycarbonic acids, polyamino acids and diglycolamine.

9. JV�according to claim sob 8, in which the aqueous phase A1 contains one diglycolate.

10. A method according to any one of claims. 1-3, in which diglycolate combined with a polyamino acid.

11. A method according to any one of claims. 1-3, in which the aqueous phase A2 contains nitric acid in a concentration of from 2 to 6 mol/liter.

12. A method according to claim 8 in which the aqueous phase A2 contains the same or the same complexing agents, and the aqueous phase A1, and in the same concentration ranges.

13. A method according to any one of claims. 1-3, in which the aqueous phase A3 is a solution containing polyamino acid and hydroxycarbonate acid, the pH of which is set at 2 to 4 by the addition of the base.

14. A method according to any one of claims. 1-3, in which the aqueous phase A4 is a solution containing from 0.5 to 1.5 mol/l of nitric acid and dipicolinic, alone or in combination with carboxylic acid.

15. A method according to claim 9, in which diglycolamine is tetramethyldisilane.

16. A method according to any one of claims. 1-3, in which the organic phase used in step a) contains only the extracting solvent substance, such that the method includes all the steps from a) to e).

17. A method according to claim 16, after step e) includes the step of dividing the two extractive substances.

18. A method according to claim 17, in which the extractive separation of the two substances is performed by Stripping the acid ek�traineomega substances from the organic phase.

19. A method according to claim 18, after which phase separation of the two extractive substances includes a stage of purification of the organic phase.

20. A method according to claim 19, which after purification of the organic phase includes the step of Stripping the acid extraction of a substance in a fraction of the organic phase.

21. A method according to any one of claims. 1-3, in which the organic phase used in step a) contains the extracting solvent, the acidic substance and extracting the substance, so that the method does not include stage c).

22. A method according to claim 21, which after step (e) includes the step of treatment of the organic phase.

23. A method according to any one of claims. 1-3, in which the aqueous phase A1 is a raffinate obtained after the first cleaning cycle of the PUREX method or COACH™.



 

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FIELD: chemistry.

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EFFECT: reduction of the prime cost of the product due to the simplification of the technological process with the preservation of a degree of the uranium extraction, increased degree of the extraction of noble metals, reduction of fire hazard of the production and simplification of technological equipment construction.

12 cl, 1 dwg, 7 tbl, 6 ex

FIELD: physics, atomic power.

SUBSTANCE: invention relates to a method with which uranium from a natural uranium concentrate may be purified. The method includes extracting uranium present as uranyl nitrate in an aqueous phase A1 resulting from the dissolution of the natural uranium concentrate in nitric acid using an organic phase which contains an extractant in an organic diluent; washing the organic phase obtained at the end of step a), with an aqueous phase A2, and extracting the uranyl nitrate from the organic phase obtained at the end of step b), by circulating said organic phase in an apparatus as a counter-current of an aqueous phase A3. The extractant is an N,N-dialkylamide and the ratio between the flow rate at which the organic phase obtained at the end of step b) and the aqueous phase A3 circulate in the apparatus where step c) occurs, is greater than 1.

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15 cl, 2 tbl, 4 ex

FIELD: physics, atomic power.

SUBSTANCE: invention relates to methods of processing uranium-containing solutions obtained from dissolving fluorination cinder when producing uranium hexafluoride. The method includes dissolving cinder in nitric acid solution, extracting uranium from the fluorine-containing nitric acid solution via reduction thereof with hydrazine on a platinum catalyst, with constant removal of uranium tetrafluoride precipitate from the catalyst surface, separating the catalyst from the nitric acid solution and the uranium tetrafluoride precipitate, providing an equimolar radio of fluoride ions to uranium (IV) in the obtained solution and separating the uranium tetrafluoride precipitate from the nitric acid solution, wherein the nitric acid solution is reused to resolve fluorination cinder with preliminary fortification with nitric acid.

EFFECT: invention provides a high degree of reducing uranium and reduces the amount of nitrate- and fluorine-containing wastes.

3 cl, 2 dwg

FIELD: metallurgy.

SUBSTANCE: invention relates to hydraulic metallurgy, particularly to extraction of uranium from used phosphate solutions. This process consists in adding the solvent to initial solution, said solvent being selected from the series: KMnO4, K2Cr2O7, HNO3, H2O2, KClO3. Then, uranium-bearing sediment is precipitated by acidity correction by ammonia to pH 2.8-4.0 at 20-35°C. Filtered precipitate is treated by 20-35% solution of NaOH at 80-85°C for 1.5-2.0 hours.

EFFECT: higher yield of uranium, return of high-enriched uranium to fuel cycle, lower costs of higher safety at long-term storage, accounting and control.

2 cl, 1 tbl, 4 ex

FIELD: chemistry.

SUBSTANCE: method involves leaching a concentrate with aqueous nitric acid solution at high temperature to obtain a pulp which consists of a solid phase and an aqueous phase, filtering off the aqueous phase in form of uranyl nitrate solution, extraction refining uranium using tributyl phosphate in a hydrocarbon diluent. The filtered uranyl nitrate solution, which contains uranium in concentration of 200-400 g/l, dissolved silicon in concentration of 1.0-3.2 g/l and nitric acid in concentration of 1-2 mol/l, is held until stabilisation of viscosity before being fed for extraction.

EFFECT: preventing escape of the aqueous phase with the uranium extract, which improves efficiency of the extraction stage, lowers content of impurities in the uranium extract and enables to obtain a product which meets ASTM C 788-03 requirements.

1 dwg, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to method of uranium extraction from mother liquors. Method includes obtaining resin, modified by aminophosphonic groups, and obtaining mother liquor, which contains from 25 to 278 g/l of sulphate and uranium. After that, mother liquor is passed through resin, modified by aminophosphonic groups, in acid form to separate uranium from mother liquor. Then, elution of uranium from resin is realised.

EFFECT: possibility of sorption extraction of uranium from solutions, which contain high concentrations of sulfate.

7 cl, 1 tbl, 3 ex

FIELD: metallurgy.

SUBSTANCE: proposed process comprises leaching of uranium by nitric acid and separation of water phase from undissolved precipitate. Then, undissolved precipitate is mixed with fluorine-bearing agent, dissolution of produced charge and/or charge as a suspension in nitric acid solution. Produced solution is returned to production process for extraction of uranium. Nitric acid concentration in solution makes at least 2 mol/l. Dilution is carried out at fluorine-ion concentration at, at least, 15 g/l. Dilution is performed at 60-100°C.

EFFECT: decreased losses of uranium, minimised wastes.

4 cl, 1 dwg, 1 tbl

FIELD: chemistry.

SUBSTANCE: method involves dissolving wastes in concentrated nitric acid, oxalate precipitation from the solution, drying and calcining the americium oxalate to americium dioxide. The solution obtained by dissolving wastes with high concentration of impurity cations, one of which is ferric iron, is mixed with a reducing agent for reducing ferric iron to ferrous iron. After reduction, the solution with acidity by nitric acid of 1-2.5 mol/l is taken for extraction of americium with a solid extractant based on different-radical phosphine oxide, followed by washing and re-extraction of americium. Oxalate precipitation is carried out from the re-extract with americium concentration of not less than 3 g/l and nitric acid concentration of not less than 3 mol/l, said precipitation being carried out in two steps: adding an oxalate ion to the americium-containing solution in weight ratio to americium of (2-7):1 and then adding water to the separated precipitate in volume ratio to the precipitate of (3-8):1 and the oxalate ion in weight ratio to americium of (1-4):1. The obtained reaction mixture is boiled and taken for separation of americium oxalate from the solution.

EFFECT: high output of the product and degree of purity thereof.

4 cl

FIELD: metallurgy.

SUBSTANCE: metallic uranium obtaining method involves electrolysis of uranium dioxide in the melt of lithium and potassium chlorides in an electrolysis unit with a graphite anode and a metal cathode and release of metallic uranium on the cathode and carbon dioxide on the anode. First, mixtures of uranium dioxide and carbon are prepared in molar ratio of 6:1 and 1:1 by crushing the corresponding powders; the obtained powders are briquetted into pellets. To the anode space of the electrolysis unit, which is formed with a vessel with porous walls, which is arranged in a ceramic melting pot, there loaded are pellets obtained from mixture of uranium dioxide and carbon, and melt of lithium and potassium chlorides. To the cathode space of the electrolysis unit, which is formed with the vessel walls with porous walls and the ceramic melting pot, there loaded is melt of lithium and potassium chlorides and uranium tetrachloride in the quantity of 5-15 wt % of lithium and potassium chlorides. Electrolysis is performed at the electrolyte temperature of 500-600°C, cathode density of current of 0.5-1.5 A/cm2, anode density of current of 0.05-1.5 A/cm2, in argon atmosphere with periodic loading to anode space of pellets of mixture of uranium dioxide and carbon.

EFFECT: current yield of metallic uranium is 80-90% of theoretical.

1 ex

FIELD: chemistry.

SUBSTANCE: method involves dissolving a chemical concentrate of natural uranium in nitric acid solution, extracting and re-extracting uranium. The dissolved concentrate contains 1.2-3.7 wt % iron to uranium, 1.4-4.0 wt % sulphur to uranuim and 0-0.7 wt % phosphorus to uranium in nitric acid solution. Nitric acid and water are taken in an amount which provides the following concentration in the solution fed for extraction: uranium 450-480 g/l, iron (III) ions 0.1-0.3 mol/l, sulphate ions 0.2-0.6 mol/l, phosphate ions 0-0.10 mol/l, and free nitric acid 0.8-2.4 mol/l, and saturation of extractant with uranium during extraction is maintained in accordance with the ratio: Y ≤90.691-34.316·[SO4]+7.611·([Fe]-[PO4])+5.887·[HNO3]-9.921·[SO4]·[HNO3]+19.841·[SO4]2+7.481·([Fe]-[PO4])·[HNO3]-64.728·([Fe]-[PO4])·[SO4]+92.701·[SO4]·[HNO3]·([Fe]-[PO4])-185.402·[SO4]2·([Fe]-[PO4]), where Y is saturation of the extractant with uranium, %, and concentration in the solution fed for extraction, mol/l: [SO4] - sulphate ions, [PO4] - phosphate ions, [HNO3] - nitric acid, [Fe] - iron (III) ions.

EFFECT: obtaining raffinates with low uranium content.

1 tbl

FIELD: mining.

SUBSTANCE: invention relates to the metal mining industry and can be used for processing of gold-containing concentrates, mainly quartz, carried out prior to gravitational enrichment. The method of processing gold-containing concentrate prior to enrichment comprises supplying pulp into cavitation dispersion medium, dispersion with opening the grains of gold particles on zones of their natural adhesion with the rock. Processing of the pulp is carried out in stator-free rotary-pulsation unit, at the output of which the flow of the pulp is additionally processed by two turbulence promoters mounted on the pulp pipeline, each of which represents a swirler mounted inside the pipe. The flow of pulp processed in the rotary-pulsation unit is first directed as co-current to the first turbulence promoter, the swirler of which is mounted in the pipe with a diameter equal to the diameter of the pulp pipeline, then tangentially - to the second turbulence promoter, the swirler of which is mounted in the pipe of larger diameter, smoothly passing in the diameter at the outlet of the second turbulence promoter, equal to the diameter of the pulp pipeline.

EFFECT: improvement of efficiency of gold extraction.

3 dwg, 2 tbl, 1 ex

FIELD: nanotechnology.

SUBSTANCE: invention relates to the improved method of obtaining the metal nanoparticles for use in thermocatalytic processes of hydrocarbon crude refining. The method of obtaining the metal nanoparticles includes their recovery from organic metal salt in the thermal treatment conditions in a hydrocarbon crude medium, and the recovery is carried out of the organic salt having the formula M(OOC-R)n or M(SOC-R)n, wherein R represents alkyl, aryl, C17H33-, isoalkyl, tert-alkyl, alkylaryl, diethylamino-, possibly comprising a hydroxyl or amino group, n=1-3, and M represents a metal of the elements of the periodic table, at a temperature above the decomposition temperature of the said organic salt. The size of the nanoparticles obtained is preferably 1-100 nm.

EFFECT: improvement of the method of obtaining.

4 cl, 11 ex, 4 dwg, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to hydrometallurgical processing of mineral material, particularly scandium-containing "tailings" obtained during beneficiation of titanium-magnetite ore by wet magnetic separation. The method of extracting scandium is three-step sulphuric acid leaching of scandium, wherein at the first step, leaching is carried out with recycled solution after extraction of scandium at temperature of 30-50°C and solid to liquid ratio of 1:6-7 for 3-4 hours; the pulp is then divided into a solid phase and a liquid phase; at the second step, a portion of the solution obtained from the first step is returned to the solid phase and sulphuric acid is added to concentration of 340-360 g/l and sodium fluoride is added in amount of 20-25 kg fluorine/t solid; leaching is carried out at temperature of 95-98°C and solid to liquid ratio of 1:2.5-3 for 3-4 hours; further, at the third step, the pulp is diluted in solid to liquid ratio of 1:6.5-7.5; treatment is carried out at temperature of 95-98°C for 3-4 hours.

EFFECT: invention increases extraction of scandium, cuts the overall duration of the leaching process and consumption of sulphuric acid and sodium fluoride.

3 ex, 1 tbl

FIELD: process engineering.

SUBSTANCE: invention relates to treatment of siderite ores containing large amounts of magnesium oxide (over 9 wt %) and intended for production of two reconnaissance device with high content of iron and high-purity magnesium oxide. Proposed method comprises crushing and sizing of initial ore, magnetising annealing, dry magnetic separation of annealed product and leaching of magnesium oxide from magnetic fraction by acid solution. Magnetising annealing is carried out in conditions inhibiting oxygen entry at 480-650°C for time interval sufficient for decomposition of iron and magnesium decomposition. After magnetic separation, extracted magnetic fraction is additionally crushed to leach magnesium oxide therefrom by carbonic acid solution and to extract magnesium carbonate on heating to 75-100°C to be decomposed to magnesium oxide at 600-750°C.

EFFECT: higher ecological safety.

3 cl, 2 tbl

FIELD: metallurgy.

SUBSTANCE: technological complex includes hydraulic cyclone block with distributor of suspensions in the form of pulp, electric driven pump, suction and delivery pulp lines, coarse crushed ore supply conveyor, fine ore crushing mill, particle-size classifier, sump, technological water supply system, shutoff and control valves and automatic control and monitoring system. Each hydraulic cyclone is made in the form of cylindrical conical housing with receiving chamber in upper part, which is connected by means of feed branch pipe to pulp distributor, and equipped with cover plate with drain branch pipe and sand head piece combined at the bottom with similar header with similar head pieces of other hydraulic cyclones. Mill is connected at the inlet to coarse grained ore receiver and at the outlet to particle-size classifier having two outlet channels by means of which the latter is interconnected via fine fraction of ore with sump, and by means of the other one it is switched to mill in recirculation manner. Sump is interconnected via T-piece and suction pulp line with delivery technological water supply pipeline with possibility of controlled change-over to washout of pulp in sump, and turbine pump is interconnected with similar delivery pipeline in adjustable manner.

EFFECT: increasing efficiency and improving the quality of ore suspension separation as per fractions at reduction of power costs, increasing stability and operating life without stops for repair and replacement of quick-wearing parts; improving hydraulic cyclone designs.

5 cl, 6 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to ore suspension separation, particularly, to hydrocyclone units used in fine ore suspension separation systems in mining, metallurgy, chemical industry, etc. Proposed system comprises unit of hydrocyclones, pulp distributor whereto connected are one to eight hydrocyclones with total capacity of 550 to 2600 m3/h of separated ore suspension. Unit hydrocyclones are mounted on common frame. Every hydrocyclone is shaped to tapered-cylinder housing with intake chamber, feed and discharge branch pipes, and sand bed integrated with those of other hydrocyclones and provided with inner lining of wear resistant material. Hydrocyclone housing cylindrical part ID is 2.9-3.6 times larger than that of discharge branch pipe while cross-section of the latter makes 1.27-1.89 of cross-section area of feed branch pipe and is 5.0-14.0 times larger than that of sand bed outlet channel at taper angle of hydrocyclone housing bottom of 16-22 degrees.

EFFECT: higher efficiency and quality of suspension separation, power savings, continuous operation.

11 cl, 3 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to ore suspension separation, particularly, to hydrocyclone units used in fine ore suspension separation systems in mining, metallurgy, chemical industry, etc. Proposed system comprises unit of hydrocyclones, pulp distributor whereto connected are one to eight hydrocyclones with total capacity of 180 to 1600 m3/h of separated ore suspension. Unit hydrocyclones are mounted on common frame. Every hydrocyclone is shaped to tapered-cylinder housing with intake chamber, feed and discharge branch pipes, and sand bed integrated with those of other hydrocyclones and provided with inner lining of wear resistant material. Hydrocyclone housing cylindrical part ID is 2.7-3.3 times larger than that of discharge branch pipe while cross-section of the latter makes 1.05-1.75 of cross-section area of feed branch pipe and is 3.3-9.0 times larger than that of sand bed outlet channel at taper angle of hydrocyclone housing bottom of 18-22 degrees.

EFFECT: higher efficiency and quality of suspension separation, power savings, continuous operation.

11 cl, 3 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to ore suspension separation. Fine complex ore suspension separation system comprises set of hydraulic cyclones, pulp distributor and one to six hydraulic cyclones with total output of 12 to 70 m3/h mounted on frame support. Every hydraulic cyclone is made up of cone housing with intake chamber, feed and discharge branch pipes, and sand bed integrated along the bottom with beds of other cyclones, and furnished with inner lining from wear proof material. Cone section of hydraulic cyclone is formed by variable-thickness lining. Housing cylindrical section ID is 3.5-5.0 times larger than discharge branch pipe outlet diameter while branch pipe cross-section area makes 0.6-1.0 of feed branch pipe cross-section area and is 6-25 times larger than that of sand bed outlet channel at inner taper angle of housing bottom of 14-18 degrees.

EFFECT: higher efficiency and quality of separation, stable and reliable operation.

11 cl, 3 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to selective separation of ore suspensions. Proposed complex comprises unit of hydraulic cyclones with control valves, electrically driven pump, suction and pressure pump lines, coarse ore feed conveyor, ore fine grinder, selective classifier, sump, service water supply system, control valves and automatic control system. Every hydraulic cyclone is shaped to tapered cylinder housing with intake chamber at its top communicated via feed branch pipe with pulp distributor and provided with colder with drain branch pipe and sand bed communicated, at its bottom, via sand manifold, with similar beds of other cyclones. Ore fine grinder inlet is communicated with coarse ore intake while its outlet is communicated wit selective classifier having two outlet ducts, one being connected with sump and another one being communicated with grinder. Sump is communicated via T-joint and suction pulp line with pressure pipeline of water supply system to switch over to pulp wash-out in sump while turbo pump is communicated with turbo delivery pump.

EFFECT: higher efficiency and quality of separation, power savings, perfected design.

5 cl, 5 dwg

FIELD: metallurgy.

SUBSTANCE: production of palladium soluble in nitric acid is carried out by restoration of a suspension of a compound PdCl2 by sodium or ammonium formate in acid or weak-acid medium. Restoration is carried out at the temperature of 50-110°C.

EFFECT: production of palladium practically fully soluble in nitric acid safe in pure air atmosphere and resistant to oxidation on air without additional heating.

3 tbl, 2 ex

FIELD: autoclave hydrometallurgy, in particular hydrometallurgical reprocessing sulfide concentrates.

SUBSTANCE: method for reprocessing of sulfide concentrates with high content of pyrrotine includes blending of raw concentrate with mineral stabilizing additive; autoclave oxidative leaching of produced mixture in aqueous pulp under oxygen pressure at temperature above the sulfur melting temperature in presence of surfactant to convert non-iron metals into solution, sulfur - to elementary form, iron - to oxides; deposition of non-iron metal sulfides from oxidized pulp solution followed by recovery of non-iron metal sulfides and elementary sulfur by flotation into multiple sulfur-sulfide concentrate and iron oxides into rock refuse. Alkali or alkali-earth compounds with aluminum silicate are used as stabilizing additive, added at mass ratio of pyrrotine to total silica and alumina content of 1:(0.05-0.33) and mass ratio of copper to pyrrotine <1:55; or at mass ratio of pyrrotine to total silica and alumina content of 1:(0.5-0.8) and mass ratio of copper to pyrrotine 1:55 or more. Pyrrolitine decomposition ratio is at least 95 %, and leaching yield of sulfide mass is not less than during treatment of common pyrrotine concentrate.

EFFECT: improved method for reprocessing of sulfide concentrates.

9 cl, 1 tbl, 4 ex

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