Method for removing uranium sources from water

Abstract

The present invention relates to a method for removing a uranium source from water, a kit for removing a uranium source from water, and the use of a powder comprising (i) an alkaline earth metal carbonate, (ii) an alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) an alkali metal carbonate in a method for removing a uranium source from water.

Description

[0001] The present invention relates to a method for removing uranium sources from water, a kit for removing uranium sources from water, and the use of a powder comprising (i) an alkaline earth metal carbonate, (ii) an alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) an alkali metal carbonate in the method for removing uranium sources from water. Background Technology

[0002] Uranium is a heavy metal that, while rare, can be found in the natural environment and has been widely adopted due to nuclear testing and industrial uses. Furthermore, uranium can also be found in fertilizers, such as phosphate fertilizers, and its release into groundwater can cause particularly serious problems. Although the use of uranium for power generation remains crucial, uranium and its ions, especially cations like uranyl cations, are toxic and carcinogenic. While uranium exists in low concentrations in the Earth's crust, it can still be found in significant quantities in water sources, particularly in potable and drinking water.

[0003] Due to the aforementioned negative health effects, water treatment plants are working to reduce uranium levels, especially in drinking water. Although several solutions have been developed over the years, the solubility of uranyl cations in water remains a challenging task for removing uranium from water.

[0004] My doctoral dissertation, "Removal of Uranium from Drinking Water by Adsorption of Granular Ferric Hydroxide (GEH)," by Carsten Bahr, Faculty III of the Technical University Berlin, 2012, considered and tested several methods for reducing uranium content in water. In this regard, it is noteworthy that, for example, the chemical properties of uranium in water are highly complex, depending on pH, as multiple distinct phases exist, some even parallel, such as different hydroxide and carbonate complexes between pH 4 and 8. Another method for uranium removal is disclosed in DE4313127A1. From a thermodynamic perspective, the active phase, for example, during the precipitation of uranyl ions in an aqueous environment, remains unknown. Furthermore, other parameters such as total inorganic carbon (TIC) and water hardness, for example, are affected by calcium... 2+ The effects of ions, etc., remain unclear. So far, it is speculated that higher TIC and higher Ca... 2+The concentration of certain ions is unfavorable for uranium removal. However, it is speculated that higher concentrations of carbonate and / or calcium ions are also unfavorable for uranium removal.

[0005] Although further studies have been conducted to optimize uranium removal from water, it is still necessary to further reduce the uranium content in water, especially in potable and / or drinking water. Summary of the Invention

[0006] The inventors have discovered a method in which a further significant reduction in the amount of uranium source in water can be achieved by using a specific combination of reagents in a process step. Specifically, the inventors have found that adding an iron (III) salt and a powder containing an alkaline earth metal carbonate, optionally (ii) an alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) an alkali metal carbonate, at a suitable pH, achieves a remarkable reduction in the amount of uranium source in water, an effect that cannot be achieved by any single method alone. Furthermore, the inventors have found that, according to the prior art, calcium ions and carbonate ions have an adverse effect on the removal of uranium source, particularly uranyl cations, from water, but they do not affect the process because both ions are added with the powder. Even if Ca... 2+ The same applies to both total inorganic carbon (TIC) and carbonates. Conversely, the inventors found that carbonates and Ca... 2+ It has a synergistic effect in uranium removal.

[0007] In a first aspect, the present invention relates to a method for removing uranium sources from water, comprising:

[0008] a) Provide water containing uranium sources;

[0009] b) Optionally, the pH of the water containing the uranium source is adjusted to a range between 4.5 and <7.0;

[0010] c) Add an iron(III) salt, for example, an aqueous solution of an iron(III) salt, to the water containing the uranium source;

[0011] d) Adding the powder to the water, wherein the powder comprises (i) an alkaline earth metal carbonate, optionally (ii) an alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) an alkali metal carbonate, and forming a precipitate comprising the uranium source; and

[0012] e) Remove the precipitate containing the uranium source.

[0013] In addition, a kit for removing uranium sources from water was disclosed, comprising, in individual containers, […].

[0014] - Iron(III) salts, especially aqueous solutions of iron(III) salts; and

[0015] - A powder comprising (i) an alkaline earth metal carbonate, (ii) an alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) an alkali metal carbonate.

[0016] In addition, the present invention relates to the use of powders comprising (i) alkaline earth metal carbonates, (ii) alkaline earth metal compounds selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) alkali metal carbonates in a method for removing uranium sources from water.

[0017] Other aspects and embodiments of the invention are disclosed in the dependent claims and can be obtained from the following description, drawings and examples, but are not limited thereto.

[0018] Attached Figure

[0019] The accompanying drawings are intended to illustrate embodiments of the invention and to provide a further understanding thereof. They serve as an explanation of the concepts and principles of the invention in conjunction with the description. Other embodiments and many of the described advantages can be seen from the drawings. Elements in the drawings are not necessarily to scale. Unless otherwise stated, identical, functionally equivalent, and operationally equivalent features and parts are indicated by the same reference numerals in the drawings.

[0020] Figure 1 and 2 An exemplary method of the present invention is illustrated schematically.

[0021] Detailed Description of the Invention

[0022] definition

[0023] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] Within the scope of this invention, the uranium source is not particularly limited, as long as it is in water. Specifically, the uranium source is dissolved in water, i.e., a soluble uranium compound or ion. Common sources of uranium in water are, for example, uranyl cations, particularly uranyl(VI) ions UO2. 2+ And complex uranium compounds and ions, such as UO2(OH)2 and UO2(CO3). 2- UO2(CO3)3 4- and UO2(OH)4 2- Using this method and kit, especially for uranyl(VI) ions (UO2), 2+At least some of the uranium and / or its complexes may be removed, but the removal of at least some of the other uranium-containing substances that may be present in the solution due to equilibrium reactions or other reasons is not excluded.

[0025] While uranium sources can be removed from water in this kit and method, it is not necessary to remove all uranium sources; that is, quantitative removal is performed, but only a portion of the uranium sources are removed, for example, reducing their content below a specific expected value before continuing to supply them to, for example, consumers. In particular, in this method, the amount of at least one soluble uranium source in the water is reduced, and further particularly the total amount of soluble uranium compounds and / or ions in the water is reduced.

[0026] Unless otherwise stated or the context clearly indicates otherwise, quantities in this invention are given in wt.%

[0027] Before providing a detailed description of the invention, it should be understood that the invention is not limited to the specific components of the process steps of the methods described herein, as such methods can vary. It should also be understood that the terminology used herein is for describing particular embodiments only and is not intended to be limiting. It must be noted that the singular forms “a,” “an,” and “the” used in the specification and appended claims include singular and / or plural references unless the context explicitly specifies otherwise. For example, the term “a” as used herein can be understood as a single entity or as “one or more” entities. It should also be understood that, unless the context explicitly specifies otherwise, the plural forms include singular and / or plural designations. Furthermore, it should be understood that, given a range of parameters defined by numerical values, these ranges are considered to include these limiting values.

[0028] In a first aspect, the present invention relates to a method for removing uranium sources from water, comprising:

[0029] a) Provide water containing uranium sources;

[0030] b) Optionally, the pH of the water containing the uranium source is adjusted to a range between 4.5 and <7.0;

[0031] c) Add an iron(III) salt, for example, an aqueous solution of an iron(III) salt, to the water containing the uranium source;

[0032] d) Adding the powder to the water, wherein the powder comprises (i) an alkaline earth metal carbonate, optionally (ii) an alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) an alkali metal carbonate, and forming a precipitate comprising the uranium source; and

[0033] e) Remove the precipitate containing the uranium source.

[0034] Specifically, the steps in this method are performed in a given order, i.e., a), b), c), d), e). Furthermore, the removal of uranyl (UO2) from water is particularly important. 2+ )cation.

[0035] In this method, it is not excluded that further steps are performed in addition to steps a) to e). According to some embodiments, no additional steps are performed between two or more of these steps, such as between steps a) and b), between steps b) and c), between steps c) and d), and / or between steps d) and e). It is also not excluded that further steps are performed after step e).

[0036] In this method, there are no particular restrictions on the water containing the uranium source provided in step a). The water can come from any source, including natural water, mineral water, potable water, drinking water, mining wastewater, groundwater, open-pit mine lakes, fertilizer production, wastewater from fertilization areas, etc., especially water from drinking water or fertilizer production, such as the production of phosphate fertilizers, for example, phosphate fertilizer. There are also no particular restrictions on the water supply, and the water can flow continuously or discontinuously. Furthermore, the entire method can be carried out under continuous or discontinuous flow, or only some steps can be performed continuously while others are discontinuous. In this method, it is also possible to provide only a portion of the water source without treating another part of the method, i.e., dividing the water source into two or more different streams and applying the method only to a portion of the different streams (e.g., a single stream), for example, as a tributary. The different streams can then be merged again, such that a single stream contains the original amount of uranium source, while the stream treated by this method has at least partially removed uranium source, such that after merging the streams, the resulting stream still has a reduced amount of uranium source compared to the original water. In this way, reagents can be saved in this method while still obtaining a satisfactory amount of uranium source, for example, below a given limit. Furthermore, partial water flow can be treated more efficiently, for example, due to better contact with different reagents.

[0037] Step b) optionally adjusts the pH of the water containing the uranium source to a range between 4.5 and <7.0, without particular limitation, and is an optional step. According to a preferred embodiment, step b) is performed. According to a preferred embodiment, the pH is adjusted to a range between 5.0 and <7.0, more preferably between 5.2 and 6.8, further preferably between 5.4 and 6.6, even more preferably between 5.6 and 6.4, particularly between 5.7 and 6.3, for example between 5.8 and 6.2, for example between 5.9 and 6.1, for example approximately 6.0. For this purpose, the pH of the water can be appropriately measured before step b). Surprisingly, it has been found that setting a slightly acidic pH is beneficial for steps c) and d), particularly step d).

[0038] There are no particular restrictions on adjusting the pH of the water. A suitable pH value can be set based on the initial pH by adding appropriate reagents, such as acids or bases. In some implementations, the pH of the water is measured before adding the appropriate reagent, and then the reagent is selected based on the measured pH. If the pH is too alkaline, at least one acid, especially a mineral acid, and further particularly a non-oxidizing mineral acid, is added. If the pH is too acidic, at least one base is added, such as an alkali metal hydroxide solution or an alkaline earth metal hydroxide, preferably a NaOH solution.

[0039] According to some implementation schemes, adjusting the pH of the water containing the uranium source in step b) includes:

[0040] bi) measures the pH of water containing uranium sources, and

[0041] b-ii) Add an acid, particularly an aqueous solution of an acid, to the water containing the uranium source, wherein the acid is preferably an inorganic acid, particularly an aqueous solution of hydrochloric acid and / or an aqueous solution of sulfuric acid. Particularly preferred is the use of an HCl solution in step b). The concentration of the acid in the aqueous solution is not particularly limited and can be between 0.5% and 40% w / w, preferably between 0.8% and 35% w / w, more preferably 1% and 30% w / w, for example between 3% and 25% w / w, between 5% and 20% w / w, for example between 7.5% and 15% w / w, for example about 10% w / w.

[0042] Add a suitable reagent, such as at least one acid, until a suitable pH is obtained in step b). After the addition of the reagent, the pH can be controlled by a suitable pH measurement, for example, using a continuous pH measurement device, whether in continuous or discontinuous flow.

[0043] If the pH of the water in step a) is alkaline, i.e., >7.0, or has a pH of 7.0, then optional step b) is specifically performed. This is typically the case for most water sources, so step b) is performed according to certain embodiments. However, if the pH is acidic, i.e., below 7.0, particularly 6.0 or below, step b) can also be omitted. When the water is too acidic, an alkali can be added, as described above. Furthermore, it should be considered that a further decrease in pH can be achieved in step d) due to the addition of iron (III) salts, making it less problematic to start from an acidic pH after step a). By setting the pH in step b), the equilibrium of the uranium source in the water can be appropriately set so that the uranium source exists primarily in a form capable of reacting appropriately with the substances in steps c) and / or d).

[0044] Furthermore, there are no particular limitations on adding an aqueous solution of an iron(III) salt, such as an iron(III) salt, to the water containing the uranium source in step c). The inventors have found that iron(III) salts are particularly useful when the powder in step d) is added, especially subsequently. While there are no particular limitations on the iron(III) salt, a suitable water-soluble iron(III) salt is preferred. According to some embodiments, the iron(III) salt is ferric chloride (III) and / or ferric sulfate (III), preferably ferric chloride (III). In particular, the aqueous solution of the iron(III) salt is appropriately diluted. In particular, the inventors have found that adding iron(III) ions in step c) before adding the powder in step d) can achieve the effect of reducing the amount of uranium source.

[0045] According to certain embodiments, iron (III) salt, particularly ferric (III) chloride, is added in an amount of 1-100 mg / L of water, preferably 2-50 mg / L of water, more preferably 2-25 mg / L of water, even more preferably 3-20 mg / L of water, and even more preferably 8-19 mg / L of water, particularly preferably 14-18 mg / L of water, for example 15-17.5 mg / L, for example 16-17 mg / L, for example about 17 mg / L. This means that adding this amount of iron (III) salt results in a final iron ion concentration of 1-100 mg / L of water treated by this method, preferably 2-50 mg / L, more preferably 2-25 mg / L, even more preferably 3-20 mg / L, and even more preferably 8-19 mg / L, particularly preferably 14-18 mg / L, for example 15-17.5 mg / L, for example 16-17 mg / L, for example about 17 mg / L. In particular, it has been found that at such concentrations, the amounts of counterions of the salt, such as chloride and / or sulfate ions, are acceptable and do not interfere with the reaction.

[0046] According to certain embodiments, aqueous solutions of iron(III) salts are prepared for addition to water, particularly in situ. Surprisingly, solutions prepared in this in situ yielded better results. Without being bound by any theory, it is speculated that this enhances the formation of iron(III) colloids in the water to be treated.

[0047] Furthermore, the inventors specifically discovered that performing step c) before step d), and particularly after step b), yielded improved results. Without being bound by theory, it is hypothesized that iron(III) ions can form suitable hydroxide colloids at appropriate pH levels, thus positively impacting subsequent uranium removal. In this regard, the inventors noted that the colloids would have a negative surface charge at pH 6, which appears to have a positive effect on uranium precipitation, while at pH 8, the iron hydroxide colloids have a positive surface charge. Zero charge should be observed at around pH 7. Moreover, no such effect was observed with iron(II) ions, which are considered too water-soluble. It was also found that performing step c) after step b) could further lower the pH, with a suitable pH after c) likely between 5 and 6, for example, between 5.2 and 5.8, and a target pH after c) likely of, for example, 5.5.

[0048] Step d) involves adding powder to water, wherein the powder comprises (i) an alkaline earth metal carbonate, optionally (ii) an alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) an alkali metal carbonate, and forms a precipitate containing a uranium source without particular limitation. According to some embodiments, at least one calcium salt is present as compound (i) and / or optionally compound (ii). Specifically, step d) is performed after step c). According to a preferred embodiment, the powder in step d) is added in a dry state, i.e., without anhydrous or any other solvent. In this regard, it is preferable to coat the powder with a device that can keep the powder dry, as its components may be hygroscopic. Without being bound by any theory, it is presumed that the addition of dry powder promotes the formation of iron (III) colloids, which act on the adsorption and / or binding of the uranium source. In particular, if an alkaline earth metal compound selected from chloride and / or nitrate compounds is present, especially an alkaline earth metal chloride, this appears to lead to supersaturation and kinetic effects during the precipitate formation process. In this regard, anhydrous calcium chloride, as a hemihydrate and / or dihydrate, is particularly preferred as an alkaline earth metal compound, while highly hydrated compounds such as hexahydrate are less preferred, likely due to the increased water content in the molecule. The addition of the dry powder can be appropriately carried out using suitable application equipment, such as a metering unit.

[0049] The powder added in step d) comprises (i) an alkaline earth metal carbonate, optionally (ii) an alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) an alkali metal carbonate. While other components, such as dropper aids, are not excluded, the powder preferably consists of (i) at least one alkaline earth metal carbonate, optionally (ii) at least one alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) at least one alkali metal carbonate, except for unavoidable impurities. According to a preferred embodiment, in step d), and in the powder used in this kit and application, the powder comprises component (iv), i.e., at least one alkali metal carbonate, and according to a particularly preferred embodiment, in step d), and in the powder used in this kit and application, the powder comprises components (ii) and (iv), i.e., alkaline earth metal compounds selected from chloride and / or nitrate compounds, particularly alkaline earth metal chlorides, and at least one alkali metal carbonate.

[0050] In the powder of step d), and in this kit and application, component (i) is not particularly limited, as long as it is an alkaline earth metal carbonate, such as magnesium carbonate, calcium carbonate, strontium carbonate and / or barium carbonate. Preferably, component (i) is magnesium carbonate and / or calcium carbonate, particularly preferably calcium carbonate.

[0051] In the powder of step d), and in this kit and application, optional component (ii) is not particularly limited, as long as it is an alkaline earth metal compound selected from chloride and / or nitrate compounds, preferably magnesium chloride, calcium chloride, magnesium nitrate and / or calcium nitrate, more preferably calcium chloride and / or calcium nitrate, particularly preferably calcium chloride, and particularly preferably anhydrous calcium chloride as a hemihydrate and / or dihydrate.

[0052] In the powder of step d), and in this kit and application, component (iii) is not particularly limited, as long as it is an alkali metal bicarbonate, such as lithium bicarbonate, sodium bicarbonate (baking soda) and / or potassium bicarbonate, preferably sodium bicarbonate, optionally mixed with potassium bicarbonate.

[0053] In the powder of step d), and in this kit and application, optional component (iv) is not particularly limited, as long as it is an alkali metal carbonate, such as lithium carbonate, sodium carbonate (soda ash), potassium carbonate, and preferably sodium carbonate. If magnesium carbonate and / or calcium carbonate are used as component (i) in the powder, it seems unnecessary to include compound (iv). However, if it is included, it appears that enhanced precipitate formation can be achieved.

[0054] In the powder of step d), and in this kit and application, the preferred powder contains at least calcium carbonate and sodium bicarbonate, the more preferred powder contains at least calcium carbonate, sodium bicarbonate and sodium carbonate, and the particularly preferred powder contains calcium chloride, calcium carbonate, sodium bicarbonate and sodium carbonate.

[0055] In the powder of step d), and in this kit and application, the powder typically consists of calcium carbonate, sodium bicarbonate and sodium carbonate, and particularly preferably the powder consists of calcium chloride, calcium carbonate, sodium bicarbonate and sodium carbonate.

[0056] Without being bound by any theory, it is speculated that the powder added in step d) allows for the adjustment of a suitable pH to maximize the interaction of the uranium source, which, based on the equilibrium in water, should be approximately 6-7. The lime-carbonate equilibrium in the water to be treated can be effectively influenced by the separate addition of alkaline earth metal ions, particularly calcium and carbonate ions. In particular, the processes of deacidification, hardening, remineralization, and other equilibrium processes in the water can be controlled individually in this way. Specifically, in this case, the dissolution and resorption of calcite can occur in parallel at high reaction rates. The dissolution in step d) preferably occurs in a rapid ionic reaction. Supersaturation can be avoided by adding crystals, therefore the addition of powder is preferred. The fixation of the uranium material can occur on the formed iron compound, which can then be separated.

[0057] Contrary to the method for uranium removal disclosed in DE4313127A1, particularly the metering of the powder in step d), a completely different effect was achieved. Surprisingly, the addition of an alkaline substance such as Ca(OH)₂ not only resulted in differences in kinetics and thermodynamics, particularly in the saturation index of the substances involved, but also an observable effect on the final product. When lime slurry is used, the saturation index of CO₂ is initially negative, followed by a positive saturation index of calcium, whereas in step d), the use of a mixed component, particularly as a powder, resulted in a positive saturation index for CO₂, reaching a point where both CO₂ and calcium saturation indices are zero. This thermodynamic equilibrium differs in terms of chemical potential from any process using lime slurry, as described in DE4313127A1, where uranium removal appears to be based on precipitation with phosphate. The details of these two different processes are not yet clear. However, the method in DE4313127A1 is disadvantageous because uranium complexes were observed to redissolve in an alkaline medium containing hydroxides. Therefore, setting a suitable pH prior to step d) is advantageous.

[0058] According to some embodiments, if components (i) and (ii) are present in step d), the molar ratio of components (i) and (ii) is in the range of 1:2 to 1:6; and / or, if component (iv) is present, the molar amount of component (iv) relative to component (iii) is at most 200 mol%. According to some embodiments, the molar ratio of components (i), (ii), (iii), and (iv) is in the range of 1:0:2:0 to 1:6:7:10. According to certain embodiments, the molar ratio of components (i), (ii), (iii), and (iv) is in the range of 1:2:2:3 to 1:6:7:10, preferably 1:3:4:6 to 1:5:6:9, more preferably 1:4:4.5:8 to 1:5:5.5:8.5, and / or in the range of 1:0:2:3 to 1:0:6:10, preferably 1:0:2.5:4 to 1:0:5:8, more preferably 1:0:3:5 to 1:0:4:6.

[0059] According to some embodiments, the amount of powder added in step d) is 20-500 mg / L water, preferably 35-350 mg / L water, more preferably 55-190 mg / L water, even more preferably 70-150 mg / L water, particularly preferably 80-120 mg / L water, for example 100 mg / L water, i.e., to obtain a given concentration in the water to be treated.

[0060] According to some embodiments, after step d), water is allowed to react for a certain residence time, for example, between 10 s and 15 h, between 30 s and 12 h, between 1 min and 11 h, between 5 min and 10 h, between 10 min and 6 h, between 30 min and 3 h, or for example, about 1 h. According to some embodiments, water is allowed to react for a certain residence time, for example, at least 30 min, and particularly at least 1 h after step d). With this residence time, precipitation forms well. However, it is not excluded that the reaction may allow for no residence time, for example, in flowing conditions, although in most cases, even so, there is a certain "residence time" or time available for reaction until the next step is reached. Therefore, differences in reactor design, etc., do not appear to have a significant effect on uranium removal, while in preliminary experiments, a sufficiently long residence time is observed to be advantageous.

[0061] According to some embodiments, an alkaline substance or alkaline solution is added after step d), particularly after allowing the water to react for a period of time (as described above). The alkaline substance is not particularly limited. According to some embodiments, the alkaline substance is Ca(OH)₂, NaOH, and / or KOH, preferably Ca(OH)₂ and / or NaOH, more preferably Ca(OH)₂, and the alkaline solution is an aqueous solution of Ca(OH)₂, NaOH, and / or KOH, preferably Ca(OH)₂ and / or NaOH, more preferably Ca(OH)₂. According to certain embodiments, the alkaline substance or alkaline solution is added in such a manner that its concentration is between and includes 1-500 mg / L, for example, between and includes 5-500 mg / L, for example, between and includes 10-500 mg / L, for example, between and includes 20-500 mg / L of the water to be treated, for example, between and includes 50-300 mg / L of the water to be treated, for example, between and includes 70-200 mg / L of the water to be treated, for example, between and includes 100-150 mg / L of the water to be treated. Using such an alkaline substance and / or alkaline solution, the pH can be altered again, thereby further binding and / or adsorbing uranium materials. However, care should be taken to set a suitable pH for the water after treatment, for example, in the case of potable or drinking water.

[0062] When adding alkaline substances or alkaline solutions, it is particularly preferred that the carbonate hardness of the water be as low as possible, preferably less than 1 mmol / L, and more preferably less than 0.5 mmol / L.

[0063] According to some implementation schemes, it is preferable that the water does not become alkaline before step e).

[0064] During precipitate formation, the uranium source does not need to bind with the precipitate, and simple adsorption of the precipitate is sufficient. Therefore, the precipitate contains the uranium source, but the uranium source does not need to form chemical bonds with the components of the precipitate. The inventors have found that precipitation and adsorption are possible due to the heterogeneous surface of the complex formed in step d), but the actual uranium removal mechanism may still be affected by further parameters. However, it is speculated that adsorption and / or bonding are influenced by the formed colloidal ferric hydroxide surface, neutral Fe... III (OH)3 exists in a pH range of approximately 5 to 11, with a maximum pH of approximately 8, and is a positively charged substance, Fe. III (OH)2 +The presence of precipitates within a pH range of approximately 2 to 9, with a maximum pH of approximately 5, indicates that within the pH range defined by this method, not only the complex uranium chemistry but also the complex iron(III) chemistry influences precipitate formation. Due to the complex chemistry of different Fe(III) phases, such as ferric(III) hydroxide, and the presence of other substances from the added powder, particularly carbonate ions, precipitate formation may also involve at least the adsorption of the uranium source, for example, in the form of complex ions, as well as co-precipitation and / or precipitation, depending on the specific complexes formed by the uranium source, the amount of which varies at a given pH.

[0065] Furthermore, there are no particular limitations on the removal of uranium source precipitates in step e). For example, the precipitates can be removed by filtration, flotation, etc. According to some embodiments, the water is not adjusted to an alkaline pH before step e).

[0066] According to some embodiments, step e) includes filtration, particularly through a membrane filter and / or a sand filter. According to some embodiments, the sand filter is made of filter gravel with a particle size of 0.1-1.2 mm, preferably 0.2-1.0 mm, more preferably 0.4-0.8 mm. According to some embodiments, the membrane filter has a pore size in the range of 0.10-0.70 μm, preferably 0.15-0.63 μm, more preferably 0.22-0.45 μm.

[0067] In some embodiments, a coagulant aid is added before step e). The coagulant aid is not particularly limited. For example, polyelectrolytes, such as... Anionic polyelectrolytes like 2530TR can be used as coagulant aids.

[0068] According to some embodiments, the pH of the water can be appropriately adjusted, for example, after step e), to approximately pH 7, for example, using NaOH or an aqueous NaOH solution. Surprisingly, it has been found that adding NaOH or an aqueous NaOH solution and setting an alkaline pH before step e) can lead to the redissolution of uranium materials. Therefore, according to some embodiments, the metered feeding of alkaline NaOH or an aqueous NaOH solution, according to some examples, is carried out after step e) for precipitate removal. While neutralization is generally considered beneficial for the precipitation of Fe(III) materials, it has been surprisingly found that an acidic pH is advantageous for uranium removal.

[0069] When the water is very turbid, it is preferable to include a solids removal step before step a) to avoid side reactions with the mud. There are no particular limitations on this, and it may include, for example, flotation, filtration, etc.

[0070] Exemplary methods of the present invention are as follows: Figure 1As shown. After step 1, which provides water containing the uranium source, in step 2, the pH of the water containing the uranium source is adjusted to a range between and including 4.5 and <7.0. Step 3 then involves adding an iron (III) salt, such as an aqueous solution of an iron (III) salt, to the water containing the uranium source, followed by step 4, which involves adding a powder to the water, wherein the powder comprises (i) an alkaline earth metal carbonate, optionally (ii) an alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) an alkali metal carbonate, forming a precipitate containing the uranium source. After this, the precipitate containing the uranium source is removed in step 5. Another exemplary method of the invention is as follows... Figure 2 As shown, step 2 is omitted, for example, if the water already has a suitable pH, then as described above.

[0071] Further disclosure of a kit for removing uranium sources from water, comprising, in individual containers,

[0072] - Iron(III) salts, especially aqueous solutions of iron(III) salts; and

[0073] - A powder comprising (i) an alkaline earth metal carbonate, (ii) an alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) an alkali metal carbonate.

[0074] The kit can be specifically used in this method. Therefore, the embodiments described above in conjunction with the components of the kit can also be applied to this kit, and vice versa, especially with respect to the iron (III) salt and the powder containing (i) an alkaline earth metal carbonate, (ii) an alkaline earth metal compound selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) an alkali metal carbonate.

[0075] The present invention also relates to the use of powders comprising (i) alkaline earth metal carbonates, (ii) alkaline earth metal compounds selected from chloride and / or nitrate compounds, (iii) at least one alkali metal bicarbonate, and optionally (iv) alkali metal carbonates in a method for removing uranium sources from water.

[0076] The specific implementation scheme of the powder described above in relation to the method and kit of the present invention is also applicable to the application of the present invention.

[0077] The above embodiments can be combined arbitrarily if appropriate. Other possible embodiments and implementations of the invention include combinations of features not expressly mentioned in the embodiments of the invention above or below. In particular, those skilled in the art will add various aspects as improvements or supplements to the various basic forms of the invention. Example

[0078] The invention will now be described in detail with reference to several embodiments thereof. However, these embodiments are illustrative and do not limit the scope of the invention.

[0079] Different treatment embodiments were carried out to treat water containing uranium sources.

[0080] General experimental setup

[0081] Water containing uranium is provided. This water is pumped through a treatment system comprising: a first inlet for adding a solution to adjust its pH, a second inlet for adding a solution containing iron salts, a third inlet for adding powders for treatment, and a fourth inlet for adding an alkaline solution. Subsequently, the precipitate settles in a settling tank, and a sample is extracted from the supernatant. The solution was filtered using a belt 12A filter, and the filtrate was analyzed, particularly for the remaining uranium.

[0082] After each possible addition of a component at the first through fourth inlets, water flows into the corresponding tank, where it is allowed to remain for a certain reaction / residence time. If no substance is added from the corresponding inlet, the water is also retained in the tank for better comparison of results. After the possible addition of an iron salt solution, water flows into the container and is held there for approximately 7 minutes. To allow for the possible addition of powder from the third inlet, the powder is added to the tank, where it is mixed with water using a stirrer for 30 minutes. After this mixing, the water is transferred to another reactor, where it is held for approximately 1 hour. Water flows through the system at a pump rate of 1000 L / h and a temperature of 7–16 °C. Finally, the water flows through a filter. After this filtration, a sample is taken from the treated water and the amount of residual uranium is measured.

[0083] In various embodiments, to adjust the pH to 6, 1.48 mL / L of 2N HCl aqueous solution is added to achieve a final pH of 6.01; to set the pH to 7, 0.34 mL / L of 2N HCl aqueous solution is added to achieve a final pH of 6.98; and to set the pH to 8, 0.14 mL / L of 2N NaOH aqueous solution is added to obtain a final pH of 8.01.

[0084] To add iron salts, the following solution was prepared in situ.

[0085] Weigh out ferric sulfate hexahydrate (II) and mix it with water to make a Fe(II) solution, which will be named Fe(II) below.

[0086] Weigh out ferric chloride (III) hexahydrate and mix it with water to prepare a Fe(III) solution, which will be referred to as Fe(III) below. Typically, the pH decreases upon the addition of a Fe(III) salt.

[0087] Two powder mixtures, Mixture 1 and Mixture 2, were prepared as the powders to be added. The composition of each mixture is as follows:

[0088] Mixture 1 (per 100g): Calcium chloride (hemihydrate CaCl2 + 0.5H2O) 32g, sodium carbonate 43g, sodium bicarbonate 20g, calcium carbonate 5g

[0089] Mixture 2 (per 100g): Sodium carbonate 60g, sodium bicarbonate 30g, calcium carbonate 10g

[0090] The pH may increase after the addition of powder from Mixture 1. For example, when the initial pH was set to 6, the pH decreased to 5.1 when 17 mg / L of Fe(III) salt was added to the water to be treated, and increased to 5.6 after the addition of 100 mg / L of powder from Mixture 1.

[0091] If Ca(OH)2 or NaOH is added as an alkaline solution from the fourth inlet, the final pH after addition will reach between 8 and 9.

[0092] Refer to Example 1

[0093] For reference, water is pumped through the system, filtered, and then the uranium content of the supernatant is measured.

[0094] Comparative Examples 1-8 (CE1-8)

[0095] Compared with the reference examples, in Comparative Example 1, Fe(II) salt solution was added at 17 mg / L of water to be treated; in Comparative Example 2, Fe(III) salt solution was added at 17 mg / L of water to be treated; in Comparative Example 3, powder mixture 1 was added at 100 mg / L of water to be treated; in Comparative Examples 4 to 6, after initially setting different pH values ​​(pH 6, 7, and 8), Fe(II) solution was added to CE1 and mixture 1 was added to CE3; in Comparative Examples 7 and 8, after adjusting the initial pH values ​​to 7 and 8, Fe(III) solution was added to CE2 and mixture 1 was added to CE3.

[0096] Examples 1-13

[0097] In Examples 1 and 2, the initial pH was adjusted to 6, and then 17 mg / L of water to be treated was added to Fe(III) solution, followed by 100 mg / L of water to be treated to mix 1 in powder form, and the reaction, sedimentation and filtration were carried out as described above.

[0098] Example 3 roughly corresponds to Examples 1 and 2, except that Fe(III) solution is added to achieve a concentration of 10 mg / L in the water to be treated.

[0099] In Example 4, compared to Example 3, a Ca(OH)2 solution was added after the reaction, while Example 5 roughly corresponds to Example 4, except that the concentration of powder mixture 1 was adjusted to 150 mg / L of the water to be treated.

[0100] Example 6 roughly corresponds to Example 3, except that the concentration of Fe(III) solution is increased to 14 mg / L of the water to be treated.

[0101] Example 7 roughly corresponds to Examples 1 and 2, except that mixture 2 is used instead of mixture 1.

[0102] Example 8 roughly corresponds to Example 7. However, after the reaction, a Ca(OH)2 solution was added.

[0103] Examples 9-11 roughly correspond to Examples 1 and 2, except that a Ca(OH)2 solution is added after the reaction.

[0104] Example 12 corresponds to Examples 9-11, except that the concentration of powder mixture 1 is adjusted to 150 mg / L of water to be treated.

[0105] Example 13 corresponds to Examples 9-11 except that NaOH solution is used instead of Ca(OH)2 solution.

[0106] The uranium concentration obtained after filtration, along with possible initial pH settings, possible iron salts added, their types and concentrations, possible powder types added, and the Ca(OH)2 solutions that may have been added in Reference Example 1 (ref. 1), Comparative Examples 1-8 (CE1-8), and Examples 1-8 (1-8), are given in Table 1 below.

[0107] Table 1

[0108]

[0109] *150mg / L mixture 1

[0110] As can be clearly seen from Table 1, adding iron(II) salt alone (CE 1) or adding iron(II) salt and mixture 1 did not lead to a significant reduction in uranium concentration, even with different initial pH levels (CE 4-6). Furthermore, adding Fe(III) salt solution alone (CE 2) and adding mixture 1 alone (CE 3) did not achieve a substantial reduction in uranium concentration. Moreover, when the initial pH was 7 or 8 (CE 7 and 8), adding Fe(III) salt solution and mixture 1 did not achieve a sufficient reduction in uranium content.

[0111] In contrast, after setting the initial pH to 6, the addition of Fe(III) salt and mixture 1 (Examples 1, 2, 3, and 6) resulted in a significant reduction in uranium content, with the addition of 17 mg / L Fe(III) salt yielding better results than the addition of 10 and 14 mg / L, respectively. For the addition of 10 mg / L Fe(III) salt, uranium removal was enhanced by the final addition of Ca(OH)₂ (Examples 4 and 5), with improved results obtained when mixture 1 was added at 100 mg / L (Example 4) compared to when it was added at 150 mg / L (Example 5). When mixture 2 was used instead of mixture 1, the improvement in uranium content was smaller (Examples 7 and 8 compared to Examples 1 and Examples 9-11, respectively). The best results were obtained when the initial pH was adjusted to 6, Fe(III) salt was added at 17 mg / L, mixture 1 at 100 mg / L, and Ca(OH)₂ or NaOH was added finally (Examples 9-11 and 13). Similarly, increasing the amount of mixture 1 to 150 mg / L (Example 12) yielded less favorable results for reducing uranium concentration.

[0112] The methods, kits, and applications of this invention enable improved removal of uranium sources from water. Surprisingly, the presence of total inorganic carbon and calcium ions was found to have no negative impact, contrary to findings in the prior art.

[0113] Example 14

[0114] With 1m 3 Raw water with an iron content of 1.21 mg / L and a uranium content of 14.8 g / L is introduced into a tank (approximately 500 L) at a rate of 400 mL / m³. 3 The pH was lowered to pH 6.0 by using an aqueous solution of HCl (35%). Additionally, at a concentration of 360 mL / m 3 Ferric chloride (III) solution (corresponding to 12.4 g / m³) 3 Fe and 23.6 g / m 3 The introduction of Cl ions as described above into the in-situ generated has a concentration of approximately 17 g / m 3A ferric chloride aqueous solution of Fe (pH lowered to 5.5). As described above, 100 g / m³ is added via a vibrating feeder. 3 Mixture 1 was prepared and allowed to react for approximately 30 minutes. After sand filtration and removal of uranium material until the residual concentration of uranium was 2.11 g / L and the residual concentration of Fe was 1.23 mg / L, an aqueous solution of NaOH (35%) (550 mL / m³) was used. 3 Adjust the pH back to pH 6 before reintroducing water.

[0115] Example 15

[0116] Example 15 was performed as in Example 14, except that NaOH was added before sand filtration.

[0117] The pH was 5.63 (uranium concentration 14.8 μg / L) after the addition of ferric chloride (III), 7.29 (uranium concentration 16.4 μg / L) after the addition of sodium hydroxide, and 7.41 (uranium concentration 16.9 μg / L) after filtration. Although effective uranium removal was observed with the addition of ferric chloride (III) and mixture 1, subsequent addition of NaOH until the pH became alkaline resulted in slight redissolution of the uranium. This confirms that an acidic pH prior to filtration is beneficial for uranium removal, and that the addition of NaOH is only beneficial after filtration.

Claims

1. A method for removing a uranium source from water, comprising: a) providing water comprising a uranium source; b) optionally adjusting the pH of the water comprising a uranium source in the range between 4.5 and < 7.0; c) adding a ferric salt to the water comprising a uranium source; d) adding a powder to the water, wherein the powder comprises component i an alkaline earth metal carbonate, component ii an alkaline earth metal compound selected from the group consisting of chloride and / or nitrate compounds, component iii at least one alkali metal bicarbonate, and component iv an alkali metal carbonate, wherein the molar ratio of component i, component ii, component iii and component iv is in the range of 1 :0:2:3 - 1 :6:7:10, and forming a precipitate comprising the uranium source; and, e) removing the precipitate comprising the uranium source; wherein the ferric salt is added in an amount of 1 - 100 mg / L water; the powder is added in an amount of 20 - 500 mg / L water in step d).

2. The method of claim 1, wherein, The ferric salt is an aqueous solution of a ferric salt.

3. The method of claim 1, wherein, The ferric salt is iron chloride and / or iron sulfate.

4. The method of claim 3, wherein, The ferric salt is iron chloride.

5. The method of claim 1, wherein, The molar ratio of component i and component ii in step d) is in the range of 1 :2 to 1 :

6.

6. The method of claim 1, wherein, The molar amount of component iv is at most 200 mol% relative to component iii.

7. The method of claim 1, wherein, Step e) comprises filtration.

8. The method of claim 7, wherein, The filtration in step e) is by a membrane filter and / or a sand filter.

9. The method of claim 1, wherein, A coagulant aid is added prior to step e).

10. The method of claim 1, wherein, The powder is added in an amount of 35 - 350 mg / L water in step d).

11. The method of claim 1, wherein, The ferric salt is added in an amount of 2 - 50 mg / L water.

12. The method of claim 11, wherein, The ferric salt is added in an amount of 3 - 20 mg / L water.

13. The method of claim 11, wherein, The ferric salt is added in an amount of 8 - 19 mg / L water.

14. The method of claim 11, wherein, The ferric salt is added in an amount of 14 - 18 mg / L water.

15. The method of claim 1, wherein, Step b) of adjusting the pH of the water comprising a uranium source comprises: b-i) measuring the pH of the water comprising a uranium source, and, b-ii) adding an acid to the water comprising a uranium source.

16. The method of claim 15, wherein, The acid in step b-ii) is an inorganic acid.

17. The method of claim 15, wherein, The acid in step b-ii) is an aqueous solution of hydrochloric acid and / or an aqueous solution of sulfuric acid.

18. The method of claim 1, wherein, The water is reacted for 10 min - 6 h after step d).

19. A kit for removing a uranium source from water, comprising in separate containers: - a ferric salt; and, - a powder comprising component i an alkaline earth metal carbonate, component ii an alkaline earth metal compound selected from the group consisting of chloride and / or nitrate compounds, component iii at least one alkali metal bicarbonate, and component iv an alkali metal carbonate, wherein the molar ratio of component i, component ii, component iii and component iv is in the range of 1 :0:2:3 - 1 :6:7:

10.

20. The kit of claim 19, wherein, The ferric salt is an aqueous solution of a ferric salt.

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