Novel sorbent, method of preparation and use thereof

FIELD: chemistry.

SUBSTANCE: invention relates to sorbents and use thereof. The sorbent for antimony anions comprises particles or granules of zirconium oxide and has a distribution coefficient for the antimony anions of at least 10000 ml/g at a pH in the range of 2 to 10. The sorbent comprises particles with an average particle size in the range of about 10 nm to 100 um and having a flow rate of 100 to 10000 bed volumes per hour; the granules with an average size of 0.1 to 2 mm and having a flow rate of 10 to 50 bed volumes per hour. Also claimed is a method for the novel sorbent preparation and a method for antimony and, potentially, technetium removal from aqueous solutions, specifically from nuclear waste effluents. The distribution coefficient is high, which makes the material suitable for industrial application.

EFFECT: preparation process is straightforward and the sorbent can be produced from readily available materials at moderate conditions.

20 cl, 5 dwg, 5 tbl

 

Area of technology

The present invention relates to sorbents and their application. In particular, according to the present invention proposed new sorbents for removal of oxo-anions of antimony from aqueous solutions and dispersions. The invention also relates to a method of obtaining new sorbents. In addition, the invention relates to the use of anionic sorbents for the removal of radionuclides and non-radioactive compounds of antimony and technetium, including their oxo-anionic form (antimonate and pertechnetate), from liquid nuclear waste.

The level of technology

Ion-selective agents, for example inorganic adsorbents and ion exchangers, are increasingly used to remove key radionuclides, such as Co-60, Sr-90 and Cs-137 from liquid nuclear wastes because of their radiation stability, high sorption capacity and high cleaning efficiency [1, 2]. The materials used are available on an industrial scale cation exchangers or adsorbents (e.g., zeolites, titanates, silicotitanate, hexacyanoferrate), which can effectively remove various kinds of radioactive cations. Inorganic anion is quite rare and do not have high selectivity.

Regarding the radiation exposure of personnel and equipment Co-60, Co-58 and Cs-137 are the most dangerous radionuclides in liquid waste and drains atomic�x power plants (NPP). Improved systems of neutralization significantly reduce the discharge of these radionuclides at many energy companies, and further efforts were directed at the removal of other radionuclides, such as Cr-51, Ag-110 and Sb-125, prevailing in solution after the removal of cesium and cobalt.

Recently much attention was paid to125Sb. This element can exist in a completely soluble form in drainage waters (Floor Drain Waters) [3]. In a solution of antimony can exist in two oxidation States (+3, +5) and in the form of several hydroxyl compounds (such asSb(OH)6, Sb(OH)3(water.) andSb(OH)4+depending on the pH and oxidation conditions-recovery [4]. These chemical characteristics indicate that antimony is difficult to remove from solution.

Recent tests showed that the resin used in the standard demineralization, and ISE tools are not effective at removing Sb from liquid radioactive waste [5]. However, in some cases a number of commercially available inorganic katio�ITES, such as CoTreat, it is possible with high efficiency to apply for the removal of Sb-125 from drain waters of nuclear power plants [3], but their use is obviously limited sorption activity only in relation to the cations of antimony. As for other methods, the test program conducted by Duke Power Company's Oconee plant, showed that chemical additives in combination with ultrafiltration is an effective method of removing Sb-125 [6]. The study of other ways, such as electrodeionization, and filtration using a hollow fiber, is carried out in the framework of the programme for the removal of low level waste Institute electric power research [7].

Published several papers on the topic of removal of antimony with the use of zirconium oxide [8, 9]. In these studies of zirconium oxychloride (ZrOCl2) was used as a precursor of zirconium oxide, was studied and only the absorption of cations of antimony. The result of this research shows that with the application of the zirconium oxide can be achieved absorption less than 96% of trace amounts of antimony (which corresponds to the distribution coefficient less than 2000 ml/g). Such selectivity is, however, quite unsatisfactory for industrial applications.

Equally unsatisfactory results were obtained with the use of sorbents on the basis of zirconium oxide with polyacrylonitrile (P�N) as a binder [10, 11].

In conclusion it can be noted that the separation of free from media115mIn115Cd and132I132Those by speakers with zirconium oxide was previously considered in the prior art [12].

Brief description of the invention

Based on the foregoing, the object of the present invention is to eliminate at least part of the problems in the prior art and provision of a new anionic sorbent material, which possessed a high selectivity in respect of antimony contained in NPP emissions, and therefore, would be industrially applicable.

Another object of the invention is to provide a method of obtaining new anionic sorbents capable of removing radioactive isotopes of antimony.

Another object of the invention is to provide methods and sorption devices for the removal of antimony and possibly technetium, including their oxo-anions.

In particular, the object of the invention is the creation of anionic sorbents capable of removing radionuclides selected from the group: Sb-122, Sb-124, Sb-125 and TC-99 and mixtures thereof, and the corresponding non-radioactive particle.

The concept of the present invention is to provide a new material suitable for the removal of antimony and possibly also of technetium from aqueous solutions, wherein said material contains material based on�sid zirconium, which is characterized by the distribution coefficient of antimony at least 10,000 ml/g, and is in a fine particulate form, e.g. in powder or granulated material.

This material can be obtained by deposition, wherein the precursor containing zirconium, dissolved in acid or an aqueous solution of a strong acid, the pH of the solution after dissolution of the precursor increases, preferably gradually, at least to a pH of 2, in particular to a value in the range from 2 to 10, and the precipitate is collected and after washing allocate.

This material may be precipitated together with the ion(s) of alloying substances, such as ion(s) of antimony, to obtain a material capable to adsorb technetium from aqueous solution.

More specifically, the material according to the present invention mainly characterized by what is stated in the characterizing part of claim 1.

Method of obtaining a new ion exchange material is characterized by what is stated in the characterizing part of claim 8 and a method for removing antimony and possibly technetium from aqueous solutions is characterized by what is stated in the characterizing part of claim 15. The sorption system according to the invention are characterized by what is stated in clause 20.

The invention provides significant advantages.

According to the present invention offers� the new sorbent or ion exchange material, the granules or powder of zirconium oxide, the efficiency of which is several orders of magnitude higher than the efficiency of the previously described materials containing zirconium oxide. The distribution coefficient is so high that the material can be easily applied in industry. Method of obtaining is simple and inexpensive in the sense that we can easily get the materials used in moderate conditions.

The invention will be described in more detail with help of detailed descriptions with reference to the accompanying drawings.

Brief description of the drawings

Figures 1A and 1b represent a diffractogram obtained by x-ray powder diffraction (XRD), namely in the Figure 1A presents the diffraction pattern of the material containing ZrO2and Figure 1b is a diffractogram of a material containing Zr(Sb)O2;

Figure 2 presents the distribution rate125Sb antimonate) on ZrO and Zr(Sb)O (Sb 5%) in 0.1 M NaNO3as a function of pH;

Figure 3 shows the absorption in the column of material containing Zr(Sb)O, (Sb 5%)125Sb from the simulated drain water BWR1; and

Figure 4 shows the uptake of124Sb in a column filled with a material containing ZrO, - the initial velocity of flow 22 of the layer volumes/h was changed to 8 layer volumes/h at 780 volume of the layer.

Detailed description of preferred variants of the p�giving

For the purposes of the present invention, the term "sorbent" is used interchangeably with the term "resin" to refer to a material containing zirconium oxide, according to the present invention. The specific mechanism of sorption of antimony anions and ions of technetium material according to the invention has not been elucidated. Perhaps sorption based on the exchange of ions, but it is also possible that can happen, for example, the oxidation-recovery and processes of surface complexation. Of course, a combination of different mechanisms of sorption, and the present invention is not limited to any specific mechanism.

As the sorbent material containing zirconium oxide, can be used as such, i.e. with the addition of additional sorbent particles or groups, but for the sorption of technetium from aqueous solutions preferably adding alloying agent, preferably a trivalent ion, such as ion antimony.

As mentioned above, the material according to the present invention, capable of sorbing anions antimony (antimonate), and technetium, including their oxo-anions, mainly contains particles or granules of zirconium oxide, the distribution rate at which radioactive antimony is very high. The distribution coefficient is at least 10,000 ml/g or of at least 15,000 ml/g, in private�STI, at least 50000 ml/g. Preferably, the distribution coefficient at a pH ranging from 2 to 10 is at least 100,000 ml/g and, in particular, 250000 ml/g, for example at least 500000 ml/g, it is possible to 1000000 ml/g or more.

If the sorbent or resin is a powdery material, the average particle size is from 10 nm to 100 μm, and the flow rate (also known as "bandwidth") 100 to 10000 layer volumes per hour. On the other hand, if the ion exchanger is a granular material, the average particle size is from 0.1 to 2 mm, and the flow rate from 10 to 50 volumes of the layer per hour.

Preferably, the particles or granules according to the present invention are "self-supporting" or "not containing a filler, which means that the particles or granules used in the absence of a component that would increase their mechanical strength.

"The volume of a layer is calculated from the total bulk of material in the sorption vessel.

According to the present invention a method is provided which includes a combination of the following stages:

- dissolution of zirconium compounds in an aqueous medium at a pH below 1 with the formation of a solution containing zirconium;

- increase the solution pH to a value of at least pH 2 by adding the base;

- deposition of sediment containing zirconium oxide;

- washing of the precipitate containing zirconium oxide; and

- the allocation of zirconium oxide.

A method of producing a hydrated zirconium oxide is described in reference [13]. In the known method, the salt of zirconium in the solid state are mixed with a relatively low acid concentration (0.1 M), dissolved zirconium fully. After that to create an alkaline environment (pH=11,5), needed for the reaction, which is carried out at an elevated temperature, adding an alkali metal hydroxide.

On the contrary, in the method according to the present invention, the zirconium salt is first dissolved in concentrated acid, and then the oxide/zirconium hydroxide precipitated with the base. Thus, containing the zirconium raw material is completely dissolved to oxide/hydroxide, producing a reaction (deposition), which allows to obtain a product with interesting properties, as already mentioned and as will be discussed below.

As will be discussed in more detail below, the anion exchanger may further comprise ion alloying metal such as antimony, such as antimony (III), to improve joint sorption of technetium from aqueous solution.

The precursor containing zirconium as a rule, represents a halide of zirconium or oxoguanosine zirconium, such as zirconium chloride (IV), sulfate of zirconium (IV) carbonate of zirconium (IV) nitrate, MIDC�onium (IV), xinitrc zirconium (IV), oxychloride zirconium (IV) or a mixture thereof.

In the first stage of the method the precursor containing zirconium, dissolved in an aqueous solution of a mineral acid. The mineral acid may be hydrochloric acid, nitric acid or sulfuric acid, and can also be applied to strong organic acids such as sulfonic. At the same time can be applied a mixture of two or more acids. For the acid molarity of the aqueous solution is usually from 0.1 to 10 M, and a pH of 1 or less, often close to 0 and even below 0.

After dissolving the precursor in the acid pH of the solution is increased to values in the range from 2 to 10 by adding a base or "alkaline agent". The alkaline agent may be selected from the group of: hydroxides of alkali metals, hydroxides of alkaline earth metals, ammonia and ammonium hydroxide. In the examples used ammonia. Of course, there may be used an organic base such as organic, aliphatic or aromatic amines.

As a result of increasing the pH of the zirconium oxide will be separated from the aqueous phase. It should be washed, preferably intensively, water or an aqueous solution until such time as the boundary between the supernatant and sludge will not clearly point to a weak turbidity of the liquid. The precipitate is then isolated, heated and dried to get� material according to the present invention. When to introduce alloying agent, it is preferably added to the acidic solution containing zirconium.

Depending on the ways of carrying out the washing and separation can be obtained fillers in the form of particles or granules. Typically, the particles have a size ranging from about 10 nm to about 100 μm, preferably the average particle size is from about 50 nm to 10 μm. The granules have an average size ranging from about 0.1 μm to about 2 mm, and the pellets, which are suitable for use as an absorbent on an industrial scale, typically have a size of from about 0.1 to 2 mm.

The material obtained in this way, tends to be amorphous. The term "amorphous" means a material structure, in which XRD analysis gives a wide range of the diffraction peaks. This structure can also be considered as "nanocrystalline", i.e., the material contains tiny crystals size range which is very wide. As shown by the results below, the amorphous material has excellent sorption properties in relation to antimony, and technetium especially after alloying.

It is possible to increase the degree of crystallinity by thermal or hydrothermal treatment, i.e. by heating dry or wet powder or granules, or by heating �of material in suspension.

However, in a preferred embodiment of the present invention the sorbent is in the form of vitreous granules, easily applicable in dynamic conditions without binding.

According to the present invention is also a method of removal of antimony ions from aqueous solutions, in particular from liquid nuclear waste. Generally, the method comprises the steps:

- bringing into contact an aqueous solution containing antimony, zirconium oxide, ensuring binding of antimony oxide and zirconium with providing an aqueous solution with a reduced content of antimony, and

- Department of the specified aqueous solution of zirconium oxide,

wherein the zirconium oxide comprises an anionic adsorbent or ion exchanger consisting essentially of particles or granules of zirconium oxide and having a coefficient of distribution of antimony at least 10,000 ml/g, in particular at least 100,000 ml/g.

As described above, the method can be applied for the removal of radionuclides, i.e. radioactive antimony and possibly technetium, including their oxo-anionic form of wastewater containing nuclear waste. This will be demonstrated in the examples below. However, applying the material according to the present invention, it is also possible to remove from the solution and non-radioactive ions of antimony and technetium.

For application in industrial scale sorption materialnames or provide preferably in the form of the sorption layer. In particular, the sorption material is accommodated in the sorption unit, for instance in the case of ion-exchange column. Usually the sorption plant comprises inside the housing of the sorption layer formed by the sorption material according to the present invention. Typically, the housing includes means for inputting the liquid to be treated, the passage of fluid through the sorption material and means for withdrawing treated liquid (effluent). Means for input can be connected to a source of fluid containing antimony.

Maybe a few different designs.

In traditional column post or upload material between two supporting structures for the formation of the sorption layer. The sorption layer can be placed in the high-pressure apparatus or apparatus working under normal pressure. The treated liquid may be passed through the sorbent using a piston or by flux distribution using the distribution of funds.

According to another embodiment of the proposed placement of material within a cylindrical tank with circular cross-section and is provided with a porous wall inside or outside, or both inside and outside, to ensure the supply of the fluid inside or outside in the sorption layer in a round housing. The liquid may be omitted from the outside che�from the sorption layer in the inner space, limited internal wall of the tank with a circular cross section, or Vice versa.

Of course, can be considered and other structures. Usually, when applied in production before the sorption plant according to the flow direction of filter media are used to separate liquid from cleaned solids.

The sorption unit can be only one, or may be a plurality of sorption units, at least one of which is provided with a sorption material according to the present invention. Of course, the material according to the present invention may be combined in the sorption layer or a layer in sorption install with another ion exchanger or sorbent layer.

If you have multiple sorption devices they can be placed in series (in cascade), or in parallel, or in combination of serial and parallel placement. It is desirable to have at least two units arranged in parallel, to create the opportunity for service in respect of the sorption material and to replace it in one of the machines, while other parallel units are in operation.

Further more describes the preparation of the materials according to the present invention, and then using working examples will be considered�hree properties of new materials.

Obtaining

It is possible to produce non-alloyed Zr-oxide or Zr-oxides doped with antimony. Alloying antimony is necessary for effective removal of pertechnetate.

ZrO (undoped Sb)

ZrCl4was dissolved in 3 M mineral acid (HCl or HNO3may also H2SO4) with constant stirring. the pH of a solution containing zirconium, increased to values in the range from 2 to 9, adding slow/drop by drop a concentrated solution of ammonia (25% -30%), and continued the stirring for 30 minutes. The suspension was allowed to stand for 30 minutes, clean the supernatant was decanted. Dirty the precipitate was washed by adding an equal quantity of distilled water and stirring for 5 minutes. The suspension was left to stand for 60 minutes and clear supernatant was decanted. The washing procedure was continued until until after 60 minutes of settling, the supernatant remained slightly turbid, and the boundary between the supernatant and the precipitate does not become clear. Slightly turbid supernatant was decanted and the residue was dried at a temperature of 70°C on a plate to dry for 48 hours to dry the product and the generation of particles. As shown in Figure 1A, the XRD analysis showed the obtained amorphous materials.

Zr(Sb)O (material doped Sb)

ZrCl4RA�tarali 3 M mineral acid (HCl or HNO 3may also H2SO4) with constant stirring. From 1% to 50% (atomic %) of the alloying component, chloride of antimony (III) was added to the solution and dissolved within 15 minutes. the pH of a solution containing zirconium and antimony, increased to values in the range from 2 to 9, adding slow/drop by drop a concentrated solution of ammonia (25% -30%), and continued the stirring for 30 minutes. The suspension was left to stand for 30 minutes, clean the supernatant was decanted. Dirty the precipitate was washed by adding an equal quantity of distilled water and stirring for 5 minutes. The suspension was allowed to stand for 60 minutes, clean the supernatant was decanted. The washing procedure was continued until until after 60 minutes of settling, the supernatant remained slightly turbid, and the boundary between the supernatant and the precipitate does not become clear. Slightly turbid supernatant was decanted and the residue was dried at a temperature of 70°C on a plate to dry for 48 hours to dry the product and the generation of particles. As shown in Figure 1b, the XRD analysis showed the obtained amorphous materials.

As a precursor containing zirconium, in the above-mentioned synthesis instead of zirconium chloride (IV) can also be used sulfate of zirconium (IV) carbonate of zirconium (IV) nitrate C�rcone (IV), xinitrc zirconium (IV) and oxychloride zirconium (IV).

The above synthesis is different from the synthesis described by Bhattacharyya and Dutta [8], mainly as dissolved precursor containing zirconium. Bhattacharyya was dissolved ZrOCl2in the water, while in the above-mentioned synthesis for the dissolution of the precursor containing zirconium, used acids, particularly strong acids such as mineral acids.

Removal characteristics of antimony and technetium

Zirconium oxide is thoroughly investigated on the ability to remove124Sb,125Sb and99TC, using simulated and real liquid nuclear waste. Studies were performed in static and dynamic conditions. In the static experiments determined the distribution coefficient (kdfor radionuclides. The "strength" of the sorption process involving ion exchange:

RB+ARA+B(1)

where A is a radioactive oxo-anion, such asS124b(OH)4 ), Is a be exchanged anion (e.g., Cl-) attached to a solid matrix, R+(in this application, for simplicity, consider that the monovalent anion), is characterized by the selectivity coefficient KA/B[14, 15], i.e.

KA/B=[RA][B][A][RB](2)

where [R-A] and [R-B] represent the concentrations of anions in the sorbent (e.g., mmol/g), and [A] and [B] represent the concentrations of anions in solution. The distribution coefficient (kd[14, 15], i.e.

kd=[RA][A](3)

can be represented in logarithmic form:

logkd=log(KA/BQ) log[B](4)

since the radionuclide And, usually present in the solution and the sorbent in a much lower concentration than the non-radioactive counterions In ([R-B]=Q, the ion exchange capacity) [15]. Under these conditions (radionuclides in small quantities in the system) the selectivity coefficient is a constant, and kdnot dependent on the concentration in solution of the radionuclide A. Thus, the determination of kdgives you the opportunity to clearly assess the selectivity of material and can be used to compare the effectiveness of different sorption materials. Moreover, kdcan be applied to estimate the maximum dynamic capacity of the sorbent. If [A] is the initial concentration in solution, [R-A] represents the concentration in the sorbent in the saturation state, the [R-A]/[A]=kdgives the volume of fluid cleared of a given mass of sorbent.

In the static testing of bulk distribution coefficients were determined by applying the following formula [16]:

kd=the concentration of radionuclides in the sorbentthe concentration of radionuclides in solution� A0AeqAeqVm(5)

where:

And0and Aeqrepresent volumetric activity (Bq/l) or count rate (pulses/min) in the solution before and after contact with a sorption material, respectively.

V is the volume of solution (usually 10-20 ml), and

m represents the mass of sorption material (usually 100-20 mg) in contact with the solution.

In dynamic experiments, the solutions were passed through ion-exchange column (column volume is typically 1 cm3) filled with sorption material (grain size 0.15 to 0.30 mm, which is common for small-scale tests, see Fig.2-4), at different flow velocities (typically 10-20 cm3/h). From coming out of solution was collected fractions and calculated the degree of radioactivity. The deactivation coefficient (KD) for the exiting solution was calculated as the ratio of the volume activities respectively in the incoming solution (A0) and leaving the solution (A), i.e.

KD=A0/A.

If the material in the column has a very high capacity (as in the case when small amount Radion�of Klimov removed by highly selective materials), it is often difficult to measure the sorption capacity of the column experiments because of the time and activity linkages. However, the dimension kdby definition gives a theoretical maximum sorption capacity in terms of volume of solution (ml), which can be cleaned by using a given amount (g) of the sorption material.

A study in static conditions, carried out in 0.1 M NaNO3showed that sorption materials effectively remove Sb-125 at relatively high nitrate content in a wide pH range of the solution.

Figure 2 presents the distribution rate125Sb antimonate) on ZrO and Zr(Sb)O (Sb 5%) in 0.1 M NaNO3as a function of pH.

As will be shown, the material is doped Sb, has a slightly lower absorption of Sb than the undoped material.

Table I
The chemical composition of the simulated drain water nuclear power plants, used in tests of the sorbents;125Sb (antimony) indicator was added to the drain 9000-15000 atoms per minute/10 ml
Component mg/lPWR1PWR2BWR1
Na36,8 43,390,1
K7,775,0not found
Ca0,8629029,8
N3IN3160120not found
pH8,7-9,0no data6,2

Another study using simulated drain waters NPP showed that Sb-doped Zr-oxides were removed Sb-125 from the solution in most cases to levels lower than the detection limit (table II). Even in cases when Sb-125 remained in solution, the calculated values of kdover $ 5000000 ml/g.

Table II
Distribution coefficients (kd(ml/g) Sb-125 in a simulated floor drain waters
kdSb-125 (ml/g)
Model/metal OxideZr(Sb)O (5% Sb)Zr(Sb)O (3% Sb)
PWR16 502 700not found
PWR2not found5059700
BWR1not foundnot found

"Not detectable" means that the number of Sb-125 was below the detection limit.

In the study under dynamic conditions on a column filled with Zr(Sb)O (Sb 5%), was removed Sb-125 of simulated drain waters (BWR1, see Table I) with high efficiency, the ratio of deactivation KD most of our time was approximately 300-600 (see Fig.3). The CD remained at a constant level and, therefore, did not depend on the flow rate, which during the experiment was gradually increased from 10 volumes layer/h to 50 layer volumes/h. At the conclusion of the study, when it was processed 2500 volumes layer, signs of resource depletion column (i.e. dropping KD) was observed.

The column tests in the laboratory were also conducted using actual radioactive water nuclear power plants. Water from the pool the spent fuel of the Olkiluoto nuclear power plant (BWR, Finland) contained Sb-125 level 400 Bq/l (table III).

Table III
The fuel / water Olkiluoto-1 BWR, Finland
ComponentValueUnit of measure
Conductivity1µs/cm
SO424ág/l
Oxalate1,5ág/l
Cl-2ág/l
Sb-125396Bq/l
Cs-1378,6Bq/l
Co-6011,1Bq/l

In studies on a column of 1 l (2000 layer volumes) fuel water was passed through a column containing Zr(Sb)0 (Sb 5%). Sb-125 was detected in the solution, as can be seen from the results shown in Table IV. Calculated from the minimum apparently detected activity (MDA), equal to 1.7 Bq/�, the deactivation coefficient Sb-125 mattered more than 230.

Table IV
The removal of radionuclides from drain waters on the column (see Table III)
No. cleaned the volume of the layerCD
Sb-125Cs-137Co-60
360>2301,72,7
861>2301,51,7
1354>2301,41,4
1831>2301,31,0

CD mean coefficient of decontamination.

Samples of the water coolant of the primary circuit of the reactor were obtained from stop to repair the Reactor-1 Loviisa NPP for large emissions of antimony at low temperatures from 140°C to 55°C. Chemical analysis showed that the main component of the aqueous coolant was boric acid�TA (14 g/l), and that was a small amount of dissolved iron (68 ág/l). Main gamma-emitting radionuclides in aqueous coolant was a58With (240000 Bq/l) and124Sb (637000 Bq/l). These radionuclides were present mainly in the dissolved form, by filtering (0.45 µm) was able to remove only 7.4%58With and 8.2%124Sb.

Table V
Uptake of124Sb drain water from the Reactor-1 Loviisa NPP oxides of zirconium, obtained from different precursors
The precursor containing zirconiumkd(ml/g)The precursor containing zirconiumkd(ml/g)
ZrCl4NPAZrO(NO3)2NPA
ZrOCl2NPAZr(SO4)21603250
Zr(OH)2CO32754230

NAP means below the limit de�designing. Industrial ZrO2(Merck art.8914) has kd1650 ml/g.

The materials obtained with the help of various Zr-containing precursors were removed from the primary water coolant circuit of the Reactor-1 Loviisa NPP (table V) almost all124Sb. In most cases, the content of124Sb was below the detection limit (10-20 Bq/l), and when kdyou can measure whether his values were much greater than 1,000,000 ml/g (logkd>6). On the contrary, industrial zirconium oxide, supplied by Merck KGaA, Darmstadt, Germany, showed a low value of kdequal to 1650 ml/g.

Figure 4 shows the uptake of124Sb in a column filled with material according to the present invention containing ZrO. The initial velocity of flow equal to 22 layer volumes/h, changed to 8 layer volumes/h at 780 volume of the layer.

Column filled with undoped material containing ZrO, was very effective for removal of124Sb from the primary water coolant circuit. At higher flow velocity than the 22 volumes of the layer/h, the values of the deactivation coefficient was of the order of 1000 (Fig.4). When the flow rate decreased to 8 layer volumes/h, the decontamination factor was increased and was measured up to a value of 30000. In one of the waste samples, the content of124Sb was below the detection limit. IP�tanie been discontinued when cleared approximately 2800 volumes of water layer, due to the small amounts of sample. After termination of the test signs of resource depletion column was noted.

To study the stability bound of antimony in the column also conduct the test of elution.

During the test, first, 1 mmol/l solution of antimonate (marked with an Sb-125) was applied to the column, and the development of resource Zr(Sb)O was observed during the passage of approximately 500 volumes of the layer. In this phase 1 gram of Zr(Sb)O-containing material bound of 0.7 mmol of antimonate. Elution was performed exhausted column of 500 ml of boric acid (1000 ppm-1), and the eluent was collected in small fractions. All the selected fractions was determined the content of Sb-125, but it was at the background level. Thus, boric acid has been unable to wash any number of Sb-125 from a material that demonstrates an extremely strong bond Sb-125 with the material.

Thus, according to the invention proposed materials containing zirconium oxide, with an extremely high ability to absorb Sb, so in many cases, the content of Sb in solution drops below the detection limit. When kdit is possible to measure its value exceeds 1000000 ml/g, this means that the sorption capacity of ion exchangers according to the present invention m�may be even higher than 1000 m 3/kg. These values are much higher than those obtained for industrial materials (1650 ml/g) or experimental materials (794 ml/g, Reference 8).

The list of references

1. R. Harjula, J. Lehto, "Selective Separation of Radionuclides from Nuclear Waste Solutions with Inorganic Ion Etc", Radiochim. Acta, 86 (1999) 65.

2. R. Harjula, A. Paajanen, J. Lehto, E. Tusa, R. Smith and P. Standring, "Additional Testing Of CoTreat Inorganic Ion Exchange Media For The Removal Of Co-60 From Thorp Pond Water", Proceedings of Waste Management 2004 Conference, February 29-March 4, 2004, Tucson, AZ.

3. R. Harjula, J. Lento, A. Paajanen, L. Brodkin and E. Tusa, "Testing of highly selective CoTreat ion exchange media for the removal of radiocobalt and other activated corrosion product nuclides from NPP waste waters", Proceedings of Waste Management '99, Tucson, AZ, February 28-March 4, 1999.

4. K. M. Krupka and R. J. Seme, "Geochemical Factors Affecting the Behavior of Antimony, Cobalt, Europium, are technetium, and Uranium in Vadose Sediments", PNNL-11485, Pacific Northwest Laboratory, Richland, Washington, 2002.

5. Electric Power Research Institute, "Analysis of Advanced Liquid Waste Minimization Techniques at a PWR", TR-109444, 1998.

6. Electric Power Research Institute, "Improved Antimony Removal Using a Chemical Treatment and Microfiltration Process", TR-109443, 1998.

7. Electric Power Research Institute, "Enhanced Liquid Radwaste Processing Using Ultrafiltration and Chemical Additives: Results of Pilot Scale and Media Testing", TR-1009562, 2004.

8. D. K. Bhattacharyya and N. C. Dutta, "Immobilisation of Barium, Cadmium and Antimony Cations Over Zirconia", J. Nuc. Sci. Technol., (1991), 28 (11), 1014-1018.

9. D. K. Bhattacharyya and N. C. Dutta, "Uptake of several tracer cations and the separation of carrier free140La from140Ba and also115mIn from115Cd using a zirconium(IV) oxide column", in Recent Developments in Ion Exchange 2, Eds. P. A. Williams and M. J. Hudson, Elsevier, 1990, pp. 67-73.

10. Eva Mistova: "Selective Sorption of Sb(V) Oxoanion by Composite Sorbents based on Crium and Hydrous Zirconium Oxides", Ion Exchange Letters, [Online] vol. 1.

11. US 2005/051492 A1 (Troy Tranter J.).

12. D. K. Bhattacharyya and S. Basu: "Separation of carrier-free 115m In from 115 Cd and I from 132 132 Those Over the zirconium oxide column", Journal of Radioanalytical Chemistry, vol.52, No. 2.

13. WO 2004/007372 A1 (Magnesium Elektron Inc.).

14. F. Helfferich, Ion Exchange, McGraw-Hill, New York 1962, p.155.

15.R.Harjula, "Ion Exchange Theory", in Encyclopedia of Separation Science, Vol. 2, p.1651, Eds. I. D. Wilson, C. F. Poole, T. R. Adlard and M. Cooke, Academic Press, London, 2000.

16. "Understanding variation in partition coefficient, kd, values", Report EPA 402-R-99-004A, Vol.1, Ch.3, United States Environmental Protection Agency, 1999.

1. Sorbent antimony anions, essentially containing particles or pellets of zirconium oxide, characterized by the distribution coefficient of antimony anions of at least 10000 ml/g at pH in the range from 2 to 10,
moreover, these particles have an average size of from 10 nm to 100 μm, for which the flow rate is from 100 to 10000 layer volumes per hour, and these granules have an average size of from 0.1 to 2 mm, for which the flow rate is from 10 to 50 volumes of the layer per hour.

2. The sorbent according to claim 1, characterized in that the distribution coefficient of the anions of antimony is at least 15000 ml/g, in particular at least 50000 ml/g; suitable coefficient of antimony is at least 100000 ml/g, preferably at least 250000 ml/g.

3. Sorbent according to any one of claims.1 and 2, obtained by the method, which includes stages:
- dissolution of zirconium compounds in an aqueous medium at a pH below about 1�adowanie solution containing zirconium;
- increase the solution pH to a value of at least 2, by adding a base;
- deposition of sediment containing zirconium oxide;
- washing of the precipitate containing zirconium oxide; and
- allocation of zirconium oxide.

4. Sorbent according to any one of claims.1 and 2, further comprising ion alloying metal such as antimony, in particular Sb (III).

5. Sorbent according to any one of claims.1 and 2, essentially containing particles or pellets of amorphous zirconium oxide.

6. A method of producing a sorbent according to any one of claims.1-5 containing zirconium oxide, which includes stages:
- dissolution of zirconium compounds in an aqueous medium at a pH below 1 with the formation of a solution containing zirconium;
- increase the solution pH to a value of at least 2, by adding a base;
- deposition of sediment containing zirconium oxide;
- washing of the precipitate containing zirconium oxide; and
- allocation of zirconium oxide.

7. A method according to claim 6, characterized in that the zirconium compound is selected from the halides of zirconium and oxoguanosine zirconium, such as zirconium chloride (IV), sulfate of zirconium (IV) carbonate of zirconium (IV) nitrate, zirconium (IV), xinitrc zirconium (IV), oxychloride zirconium (IV), or mixtures thereof.

8. A method according to claim 6 or 7, characterized in that the zirconium compound is dissolved in aqueous acid solution, preferably an aqueous solution� mineral or organic acid.

9. A method according to any one of claims.6 or 7, characterized in that the pH of the solution increased to reach values in the range from 2 to 10 by adding an alkali selected from the group including hydroxides of alkali metals, hydroxides of alkaline earth metals, ammonia and ammonium hydroxide.

10. A method according to any one of claims.6 or 7, characterized in that the precipitate containing zirconium oxide, washed with water or an aqueous solution until such time as the boundary between the supernatant and the precipitate does not become clear.

11. A method according to any one of claims.6 or 7, characterized in that the solution containing zirconium, add alloying agent, preferably containing a precursor of antimony, preferably antimony precursor (III).

12. A method according to any one of claims.6 or 7, characterized in that the zirconium oxide is amorphous.

13. Method for removing radioactive or non-radioactive antimony anions from aqueous solutions, in particular from liquid nuclear waste, which includes stages:
- bringing into contact an aqueous solution containing antimony, with the sorbent according to any one of claims.1-5 containing zirconium oxide, with the provision of binding of antimony oxide and zirconium with providing an aqueous solution with a reduced content of antimony, and
- the separation of the specified aqueous solution from the sorbent containing zirconium oxide.

14. A method according to claim 13, including, if�eenie sorbent, containing zirconium oxide, which is doped with cations of trivalent antimony, for simultaneous removal from the solution of technetium.

15. A method according to claim 13, comprising the use of a sorbent according to any one of claims.1-5 or obtained according to any one of claims.6-12.

16. A method according to any one of claims.13-15, characterized in that the step of bringing into contact is carried out in the sorption plant comprising a vessel filled with desiccant.

17. The use of the sorbent according to any one of claims.1-5 to remove anions, antimony and possibly technetium, including their oxo-anionic forms, from liquid nuclear waste.

18. The sorption unit for the removal of anions of antimony and possibly technetium, including their oxo-anionic forms, from liquid nuclear wastes containing vessel with the sorbent according to any one of claims.1-5, provided with inlet openings for liquid waste and the outlets for the treated liquid waste.

19. Apparatus according to claim 18, characterized in that the sorbent is located in the case of ion-exchange column.

20. Apparatus according to claim 18 or 19, characterized in that the sorption system comprises a sorption layer formed by the sorption material, which is located in the housing containing means for input of the purified fluid, and outputs the processed fluid, and said means input connected to a source of fluid containing antimony.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention relates to the field of the sorption technology for the extraction of radionuclides and microelements in processing of various liquid and solid objects of radio-chemical enterprises. The claimed method includes a contact with a sorbent based on transitional metal cyanoferrate, with the contact being realised in a medium of a suspension, which contains humic acid in an amount of 0.15-0.25 g/l relative to the volume of the processed solution or 0.15-0.25 g/dm2 relative to the surface of the processed object, with the ratio Ssorb:L not less than 0.001 kg/l.

EFFECT: possibility to increase the degree of purifying polluted objects of the radio-chemical industry from radionuclides and microelements.

1 tbl

FIELD: ecology.

SUBSTANCE: invention refers to marine radioecology and biogeochemistry facilities. A method for determining the thorium-234 concentration in seawater bottom deposits consists in the fact that a radiochemical yield tracer is natural long half-life α-emitting isotope 232Th, initial activity of which is determined in the sub-sample with lead γ-emission -212 if the radioactive Th and Pb balance conditions are satisfied; another sub-sample taken by separating thorium from the respective elements by oxalate deposition, is used for liquid-scintiallation (LS) spectrometric analysis of 234Th and 232Th activities as shown by β- and α-emission; that is followed by calculating thorium radiochemical yield (R) and throrium-234 initial concentration (234Thyield, Bq/kg) by presented formulas.

EFFECT: invention provides more effective and reliable determination of the 234Th content.

FIELD: ecology.

SUBSTANCE: invention refers to radiation ecology and biogeochemistry, and aims at Th concentrating from seawater and determining its concentration. The method for thorium-234 concentration in seawater is implemented in series connected absorbers containing manganese dioxide that is followed by direct radiometric measurements of absorbed 234Th as shown by its primary β-emission. Each absorber works in the radially accurate regimen, which is generated by placing the disk absorber between diaphragms. The analysed water sample is supplied into the central portion of the absorber by means of a diaphragm with a central opening, then migrates to the periphery of the sorbed surface with using the diaphragm with peripheral openings.

EFFECT: varying the sedimentation process rate in the marine reservoirs.

FIELD: chemistry.

SUBSTANCE: claimed invention relates to system for purification of wastes flow, mainly liquid or water radioactive wastes, for their safe utilisation and converting them into one or two forms, including water form for safe discharge into the environment and hardening form for safe utilisation. Realisation of claimed invention includes realisation of five steps, designated as I-V. Synchronisation of selection of sorbent substances and multirecycle option for separation of target substances from wastes flow is included as stage of step II (sorption and isotopic recovery by means of powder sorbent). Other steps correlate with sorption step (II), including oxidation (I) to deactivate or destruct existing chelating agents, solid-liquid separation (III) and selective ion exchange (IV) to achieve final desirable result of wastes flow processing. Final step consists in final processing (V).

EFFECT: possibility of obtaining predetermined specific strategy for target element by means of synchronisation of selection of sorbent substances ad multicycle option for removal of target substances from flow of radioactive wastes.

28 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to field of recycling of radioactive solutions. Composition of extraction chromatographic material for selective separation of U(VI), Th(IV), Np(IV) and Pu(IV) from nitric acid solutions contains three components. As complexants composition contains 33% of methyltrioctylammonium nitrate (MTOAN) and 1-16% of phosphoryl podand. As matrix composition contains macroporous spherical granulated copolymer of styrene with divinylbenzene. As phosphoryl podand used are derivatives of 1,5-bis[2-(oxyethoxyphosphoryl)-4-(alkyl)phenoxy-3-oxapentane of general formula I , where Alk is alkyl C1-C12.

EFFECT: extension of spectrum of highly efficient selective sorbents for extraction of U(VI), Th(IV), Np(IV) and Pu(IV) from nitric acid solutions.

8 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to radio analytical chemistry and can be used to monitor content of radionuclides in fresh and sea water, in urine of individuals exposed to radiation and in samples of different process solutions. The method of extracting radionuclides from aqueous solutions includes filtering the solution through a selective sorbent placed in the drip chamber of an apparatus used for intravenous transfusion of infusion solutions and preparing an agent suitable for gamma-ray spectrometry.

EFFECT: faster method while maintaining high efficiency and reducing measurement errors and distortion of results due to absorption of the measured gamma-radiation by filters.

2 cl, 3 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to sorption extraction of caesium radionuclides from aqueous solutions. The method of extracting caesium radionuclides includes filtering an aqueous solution through a selective sorbent which is iron-potassium ferrocyanide on a support, desorption of caesium from the sorbent with an alkaline solution containing Trilon B and potassium oxalate. The eluate obtained from desorption is further filtered through a sorbent which is nickel-potassium ferrocyanide.

EFFECT: faster caesium extraction and minimal volume of obtained concentrate containing caesium radionuclides.

1 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to sorbents produced on the basis of fly grit microspheres of thermal electric power stations and can be used for removal of radio nuclides from liquid wastes. Synthesis of sorbent comprises deposition of active component on the surface of microspheres by mixing the latter with alkaline metal ferrocyanide solution (arrester), removal of excess arrester solution whereby arrester volume retained by microspheres is defined. Transition metal salt solution is added to the mix of microspheres and arrester to hold the mix to phase separation. Thereafter liquid phase is removed while obtained sorbent is dried. In compliance with second version, sorbent synthesis comprises processing of microspheres with the solution of vanadium, or zirconium or tungsten salts and removal of excess solution whereby salt solution volume retained by microspheres is defined. Thereafter, alkaline metal ferrocyanide solution (arrester) is added thereto, excess arrester solution is removed to hold the mix to phase separation. Thereafter liquid phase is removed while obtained sorbent is dried. In compliance with both versions, sorbent is dried at 60-80°C for 1-2 hours or at a room temperature for 15-20 hours.

EFFECT: efficient removal of cesium, cobalt, cerium, europium, etc.

11 cl, 6 dwg, 6 ex, 1 tbl

FIELD: physics.

SUBSTANCE: invention relates to safe operation of nuclear power plants. Content of uranium in process media of nuclear power plants is controlled as follows: collecting a sample of the process medium, alkanising said sample to pH 9-11 by adding ammonia, filtering through a cellulose acetate membrane with freshly deposited manganese dioxide, dissolving the membrane with manganese dioxide in hydrochloric acid while boiling, reducing uranium with ascorbic acid and zinc metal to oxidation state IV, and then determining content of uranium in the solution using a photometric method using arsenazo III in a chloride medium.

EFFECT: simple and faster control, lowering the uranium detection limit 40-fold.

FIELD: chemistry.

SUBSTANCE: radionuclides and toxic metal ions are removed from water using sorbents in form of gaize crumbs with diameter of 20-50 mm.

EFFECT: invention enables to avoid intermediate operations and use of deactivating substances.

FIELD: process engineering.

SUBSTANCE: invention relates to treatment of effluents. Proposed process comprises combining of heated gas and effluents to the make the mix thereof, separating of said effluents into drops to increase the area of interface between effluents and heated gas for accelerated heat and mass transfer between drops of said effluents and heated gas. Then, heat is transferred from heated gas to effluents for their partial evaporation, portion of effluents drops are removed from said mix for making of gas without fluid and concentrated fluid, and separation of suspended solids from concentrated fluid. Fluid concentration system comprises the concentrator unit. Note here that said concenytrator comprises gas inlet, gas outlet and mixing channel arranged there between. Note also that said mixing channel has contracted section for gas flow to up its rate at flowing from said inlet to said outlet. This system comprises fluid inlet pipe for liquid to be concentrated to be injected into mixing channel. Note here that said pipe is arranged in mixing channel between gas inlet and contracted section. Fog catcher is arranged downstream of concentrator unit and includes gas passage connected to gas outlet and including fluid collector to remove fluid from gas in fog catcher gas passage, and removed fluid connection vessel. Blower is connected to fog catcher to create gas flow to be forced to mixing channel and gas passage.

EFFECT: higher efficiency of treatment.

27 cl, 2 tbl, 17 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing a hydrogen-containing product and one or more products in the form of liquid water using catalytic steam reforming of hydrocarbons. The invention relates to a method wherein part of feed water is heated by a reforming product and the other part of feed water is heated by gaseous combustion products before feeding the feed water into a deaerator. Water contained in the gaseous combustion products is condensed to obtain a product in the form of liquid water. The present method can be combined with a water thermal treatment process.

EFFECT: easier extraction of water from gaseous combustion products, availability of low-grade heat of the reforming product stream for the water thermal treatment process.

19 cl, 8 dwg, 3 ex

FIELD: chemistry.

SUBSTANCE: method of purifying waste water from hexavalent chromium compounds includes reaction thereof with an iron-containing dispersant with simultaneous exposure to a magnetic field generated by an electromagnet to obtain an insoluble precipitate. The iron-containing dispersant used is ground iron or steel chips. Exposure is carried out using a controlled magnetic field, the direction of the intensity vector of which is varied by periodically changing the polarity of current in the electromagnet windings, and the intensity value is controlled by varying the value of current in the windings. A chromium hydroxide Cr(OH)3 precipitate is obtained by neutralising the unreacted mixture with an alkali.

EFFECT: high degree of purity of waste water while cutting the duration of the process, easy implementation and high efficiency of the method.

1 dwg, 2 ex

FIELD: process engineering.

SUBSTANCE: invention relates to water treatment. Treatment of water flow fed from Fischer-Tropsch reactor comprises the fed of water flow portion to aerator, to distiller and /or evaporator and therefrom to said aerator again. Note here that process gas is fed to said aerator to produce gaseous flow to be fed to the plant for production of synthesis gas.

EFFECT: possibility to use at least a portion of water flow fed from Fischer-Tropsch reactor as a process water for production of synthesis gas.

14 cl, 1 dwg

FIELD: machine building.

SUBSTANCE: electrohydraulic water activation installation comprises a chamber filled with water and equipped by electrodes, a cover with a channel for water supply. The chamber is limited by a recess in the piston bottom, cylinder walls and the cover with a channel for water supply, a plug with an insulated positive electrode is screwed into the cover, a cylindrical electrically insulated spring-damper is installed between the bottom part of the cylinder additionally serving as a negative electrode and the piston, the lateral part of the cylinder is fitted by a hole to discharge water after electrohydraulic impact in the water-filled chamber from a corona discharge between the electrodes at switching on of a high-frequency generator of primary pulses.

EFFECT: improvement of electrohydraulic water activation efficiency.

1 dwg

FIELD: chemistry.

SUBSTANCE: surface of a film of oil or oil products is treated with a reagent which contains a natural polymer and the reaction product is collected. The reagent used is polysaccharide microgel with mass of 20000-200000 Da and particle size of 50-600 nm in an aqueous solution with concentration of not less than 0.2 g/l. According to the first version of the method, before and after spraying the reagent, the periphery of the film of oil or oil products is treated with a biodegradable surfactant in the form of an aqueous solution with concentration of not less than 0.1 g/l. According to the second version of the method, the reagent is first mixed with a biodegradable surfactant in the form of an aqueous solution with concentration of not less than 0.1 g/l. Mixing is carried out until the ratio of the polysaccharide microgel to the biodegradable surfactant is 12:1-2:1.

EFFECT: high efficiency of the process of collecting oil or oil products from a water surface, low specific consumption of reagents and low residual content of said reagents in water.

2 cl, 6 ex

FIELD: oil and gas industry.

SUBSTANCE: invention can be used in gas and oil production industry for associated crude iodine production from iodine-lean confined groundwater. The method is implemented by a sequence of electrochemical iodide ion oxidation, molecular iodine sorption on carbon, electrochemical reduction of iodine to iodides, and desorption. All stages are performed in the same chemical reactor represented by a sorption column. Activated carbon with minimum iodine adsorption capacity of 1,000 mg/g is used as a sorbent. Graphite electrode at the column bottom is used as an anode, copper cathode in the form of plate at the column top is used as cathode. After the carbon is saturated with iodine, electrode polarity is reversed to desorb iodine from carbon in the form of iodide ions. Confined groundwater, including one with low iodine content, is used as iodine source.

EFFECT: enhanced iodine production efficiency.

2 cl, 1 dwg, 1 tbl, 1 ex

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to means for protection against contaminants introduced by gravity draining at steam pumping and/or those peculiar thereto. This system is used at the plant based on gravity draining at steam pumping for production of heavy oil. This control system allows the simultaneous control over silicon dioxide, hardness and oil contamination existing in evaporator feed water.

EFFECT: ruled out heat exchange surface fouling, higher reliability.

9 cl, 16 dwg

FIELD: chemistry.

SUBSTANCE: invention can be used in industry at the stage of fine or additional purification of water from traces of heavy metal ions, in the purification of vapour condensate in boiler houses and TPP plants in the creation of closed technological water circulation. To realise the method of ion-exchange water purification sewage waters and technological solutions are passed through a sorbent, containing hydrazide groups. as the sorbent used is activated carbon, preliminarily processed with a gas mixture of ammonia and hydrazine, taken in volume ratios of 1:2-2.5, at a temperature of 350-450°C. The method provides the removal of ions of metals with a variable valence: Cu2+, Zn2+, Ni2+, Cr3+, Fe3+, as well as ions of metals: Bi3+, Zr4+, Sr2+, Co2+ from water, with the preservation by the sorbent of the sorption activity in a wide range of the water solution pH values.

EFFECT: purification of water from traces of heavy metal ions.

1 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to water purification by crystallisation and can be used in everyday life, food industry and medicine. The water purification apparatus includes a temperature-controlled heat-exchange vessel 1, means of feeding source water for purification and means 2 of draining ice water and liquid concentrate of contaminants, means 3 of cooling and freezing water and means 5 of melting ice with cooling 4 and heating elements 6, a control unit 7 connected to the means of feeding source water for purification and draining ice water and liquid concentrate of contaminants 2 from the heat-exchange vessel 1 and means of cooling and freezing water 3 and melting ice 5. The heat-exchange vessel 1 has a flat slit-type internal cavity or an annular slit-type cavity 15, and one of the walls of the heat-exchange vessel 1, which is free from the cooling 4 and heating elements 6, is made of transparent material and has one or more internal air cavities 17.

EFFECT: invention improves the quality of water purification and enables to monitor the purification process.

3 dwg

FIELD: chemistry.

SUBSTANCE: method includes pyrohydrolysis in gas phase of fluorine containing zirconium salts in presence of water steam. As zirconium salt applied is zirconium tetrafluoride. Pyrohydrolysis is realised by heating of reactor to 900-950°C, with water steam temperature being from 700 to 1200°C, preferably 900-1000°C. Water steam is obtained by burning hydrogen in oxygen in burner, with dosed introduction of additional quantity of water steam, obtained by its evaporation at boiling temperature, into their volume.

EFFECT: invention makes it possible to obtain high-quality zirconium dioxide powder.

2 cl, 1 dwg, 1 ex

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