Processes for recovery of uranium

Abstract

To provide an improved method for recovering uranium.SOLUTION: The present disclosure describes a method of recovering uranium including a continuous ion exchange (CIX) process including a single cycle or a dual cycle CIX process and at least a gradient elution or resin crowding process. The present disclosure also describes an apparatus including a single cycle or dual cycle CIX system and a gradient elution and / or resin crowding system. The present disclosure describes apparatus and process for recovering uranium from a source that involve a combination of one or more CIX processes and at least a gradient elution or resin crowding process to enhance the purity of the obtained uranium. In embodiments, the apparatus and process for recovering uranium described herein include a CIX apparatus and a gradient elution and / or resin crowding system.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to processes and methods for the recovery of uranium. [Background technology]

[0002] Uranium is an important heavy metal used in many ways in our daily lives. As an example, uranium provides nuclear fuel for generating electricity in nuclear power plants. It is also used industrially as a radioisotope, in medicine for diagnostic purposes, in food preservation, and in crop and livestock cultivation. Uranium is found in the Earth's crust, rocks, and seawater and can be recovered from the ocean. However, it is not concentrated enough in seawater to be economically recoverable.

[0003] Uranium is also found in phosphate rock, and different processes have been developed for the recovery of uranium from the phosphoric acid produced from phosphate rock. Three of the processes include the DEPA-Topo process, developed at Oak Ridge National Laboratory, which uses di(2-ethylhexyl)phosphoric acid and trioctylphosphine oxide as extractants; the OPAP process, also developed at Oak Ridge National Laboratory, which uses octylphenyl acid phosphate ester as the extractant; and the OPPA process, developed by Dow, which uses octylpyrophosphate as the extractant. However, these processes are based on solvent extraction (SX) technology, in which the extractant is dissolved in some kind of diluent, such as a high-purity kerosene-like solution, and then used in this diluted form for the recovery process. To eliminate the operational problems associated with these solvent extraction systems, particularly the potential for trace amounts of solvent to enter the phosphoric acid process after the U extraction process, which could cause major problems in rubber-lined equipment, attention is being paid to developing non-solvent extraction systems.

[0004] Phosphoric acid is an alternative source of uranium, depending on the starting uranium content in the phosphate rock. The presence of uranium in wet-process phosphoric acid has been well established, and uranium recovery from wet-process phosphoric acid is also commercially practiced. Ion exchange systems have also been used to recover uranium, and fixed-bed ion exchange systems have been used to recover uranium from various conventional sulfate and carbonate solutions (non-phosphate rock sources). Typically, these solutions are produced from the leaching of various ores, or from so-called "in situ" leaching, in which the leach solution is injected into the ground to leach out U-bearing materials, which are then recovered in a pumping well system.

[0005] U.S. Patent No. 9,702,026 discloses a process for the recovery of uranium from wet process phosphoric acid using a single or dual cycle continuous ion exchange (CIX) system. While prior art CIX systems simplify the recovery of uranium from wet process phosphoric acid, improvements are still needed to increase the purity of the recovered uranium. Summary of the Invention [Means for solving the problem]

[0006] The present disclosure describes an improved method for recovering uranium involving gradient elution and / or resin crowding processes. In embodiments, gradient elution and resin crowding are used in combination with one or more CIX processes. In embodiments, the method includes a single CIX process (single-cycle CIX process) that includes a gradient elution or resin crowding process. In embodiments, the method includes two CIX processes (dual-cycle CIX process), each including a gradient elution or resin crowding process, or only one of the CIX processes includes a gradient elution or resin crowding process.

[0007] The present disclosure also describes a CIX apparatus that includes a single or dual cycle CIX system and at least a gradient elution or resin crowding system for recovering uranium. [Brief explanation of the drawings]

[0008] [Figure 1] Figure 1 shows an exemplary single-cycle CIX apparatus and process for uranium recovery. The basic process blocks are shown along with the major material inputs and outputs. Stream numbers are listed as (Stream #) in the diagram for illustrative purposes. A gradient elution system or resin crowding system can be included in the primary CIX system.

[0009] [Figure 2] Figure 2 shows an exemplary dual-cycle CIX apparatus and process for uranium recovery. Basic process blocks are shown along with major material inputs and outputs. Stream numbers are listed as (Stream #) in the diagram for illustrative purposes. A gradient elution system or resin crowding system can be included in the primary and / or secondary CIX systems.

[0010] [Figure 3] Figure 3 shows an exemplary gradient elution system and process that can be part of the single- or dual-cycle CIX process shown in Figures 1 and 2. In this exemplary gradient elution process, the gradient elution process is included as part of a secondary CIX process of a dual-cycle CIX process involving an AE (i.e., anion exchange) resin medium. The AE medium (1) is loaded with uranyl carbonate complexes from the primary regeneration solution. As the resin progresses from section X to section X-1, exemplary acids (2)-(4), i.e., sulfuric acid, of increasing strength are added to the resin to remove contaminants loaded onto the AE medium with uranyl carbonate. In section X-2, a uranium-loaded secondary regeneration solution is produced. The AE medium is finally regenerated with the strongest acid (6) and washed with water before re-entering the secondary CIX process.

[0011] [Figure 4] Figure 4 shows an exemplary resin crowding process that can be part of the single- or dual-cycle CIX process shown in Figures 1 and 2. This exemplary resin crowding process is part of the secondary CIX process of a dual-cycle CIX process involving an AE resin. The AE media (1) is loaded with uranyl carbonate complexes from the primary regeneration solution. A portion of the uranium-loaded secondary regeneration solution is adjusted with a weak base (3), such as ammonia, and applied to the AE media. As the media progresses from Zone X to Zone X-2, the uranium in the secondary regeneration solution, converted to anionic form due to pH adjustment, is loaded onto the AE media and displaces contaminants on the AE resin. In Zone X-2, a uranium-loaded secondary regeneration solution is produced. The AE resin is finally regenerated with the strongest acid (4) and washed before re-entering the CIX process.

[0012] In both Figures 3 and 4, depending on how the secondary CIX system is configured, section X can be any section, such as section 27 in a system having a total of 30 sections. Because there is a considerable degree of flexibility inherent in the possible configurations that can be used for optimized operation, "X" is used to represent a specific section of the secondary CIX system. Sections X-X-4 are part of a gradient elution or resin crowding system. DETAILED DESCRIPTION OF THE INVENTION

[0013] Detailed Description The present disclosure describes an apparatus and process for recovering uranium from a source that involves a combination of one or more CIX processes and at least a gradient elution or resin crowding process to increase the purity of the obtained uranium. In embodiments, the apparatus and process for recovering uranium described herein includes a CIX apparatus and a gradient elution and / or resin crowding system. The CIX apparatus (and process) described herein includes a single-cycle or dual-cycle CIX apparatus (and process) and a gradient elution and / or resin crowding system (and process). In embodiments, a single-cycle CIX apparatus has a single CIX (primary CIX) system, and a dual-cycle CIX apparatus has two CIX systems, i.e., a primary CIX system and a secondary CIX system. In embodiments, a gradient elution process and / or a resin crowding process can be used in one or both cycles of a dual-cycle CIX apparatus.

[0014] The terms "recovery," "isolation," "removal," "extraction," and "purification" are used interchangeably to refer to obtaining a product, such as uranium, from a source. In embodiments, recovering uranium includes obtaining uranium in various chemical forms, including uranyl oxide, uranyl carbonate, uranyl hydroxide, uranyl ammonium compounds, including ammonium uranyl tricarbonate, and the like. Recovering uranium also includes obtaining uranyl ions. As used herein, the terms "uranium" or "U" refer to uranium in various chemical forms.

[0015] The source of uranium can be any source containing uranium. The uranium source used in the methods described herein includes sources of uranium-containing phosphates, such as phosphoric acid (PO) or raw phosphate. In an embodiment, the source of phosphate is from wet process (WP) phosphate. WP phosphate is obtained by digesting recovered phosphate rock with sulfuric acid and filtering the resulting slurry. Depending on the nature of the phosphate rock, most of the uranium that may be contained in the ore is dissolved and transported to the phosphate stream. WP phosphate is used to produce more than 90% of the world's phosphoric acid. The electric furnace process (EFP) is used to produce the remaining phosphoric acid. The majority of phosphoric acid produced by WP is used for fertilizer production. WP phosphate is less pure and concentrated than EFP phosphate, and is much cheaper to produce. A small percentage of WP phosphate is typically processed in a different solvent extraction process to produce higher quality, i.e., industrial-grade or even food-grade, phosphoric acid. Phosphoric acid produced by EFP (95-100%) is used for various industrial and food uses. EFP phosphate is much purer and more concentrated than WP phosphate, and is much more expensive to produce. EFP-produced phosphate also does not contain any uranium, as all of the uranium in the raw phosphate rock is carried over into the tailings industrial waste stream in the process.

[0016] In an embodiment, any phosphate rock that can be processed to produce WP phosphate and that contains some level of uranium is suitable as a source for recovering uranium.

[0017] In embodiments, the source of uranium includes uranium in any chemical and oxidation state or form. "Uranium in any chemical and oxidation state" refers to uranium dissolved in the source. An example is uranium dissolved in phosphoric acid during the preparation of phosphoric acid from the reaction of phosphate rock and sulfuric acid in a phosphoric acid plant. Uranium can be in either the +4 or +6 oxidation state and is most likely present as a cationic complex that can be extracted by ion exchange media.

[0018] CIX systems and processes were developed in the early 1980s. As technology advanced, second- and third-generation CIX systems were developed, which use less water and consume fewer chemicals, thus reducing operating costs. Continuous ion exchangers have multiple resin chambers that can be configured to allow for multiple processing steps. For example, there may be several chambers configured for extraction steps in the process. This can be followed by configuration of chambers to allow for resin washing, resin regeneration, and the like. Ion exchange for extraction of one or more components from the feed solution generally occurs first, which transfers the desired ions onto the column. This is generally followed by a water wash step to remove contaminated feed solution from the resin. This is followed by column regeneration and removal of the extracted ions from the column. After regeneration, another water wash step is used to minimize loss of any regeneration solution. Advantages of CIX systems include washing and regeneration of the resin media without interrupting the ion exchange process. Additionally, there is inherent flexibility in the approach that allows additional process steps, such as multiple regeneration solutions, post-loading and pre-water-washing resin treatments, and the like, to be incorporated into the CIX system configuration. These added process configurations are not practical with other ion exchange contacting systems, such as fixed-bed units. Furthermore, this flexibility allows for an entirely different approach to assessing ion exchange applications for processes that have not previously been considered practical (with previous contacting systems).

[0019] The primary difference between the CIX apparatus and process described herein and prior art methodologies, such as solvent extraction methods, is that in the CIX apparatus and process described herein, solid, polymeric, functionalized materials are used to extract uranium from the source. No liquid extractants or diluent solvents, such as high-purity kerosene, are used. Therefore, problems associated with emulsion formation and fire / explosion risks are essentially eliminated. Eliminating the need for organic diluents, such as kerosene, also eliminates the potential for downstream damage in existing operations that would result from entrained solvent materials.

[0020] The processes and systems for both chelating or complexing cation exchange (CE) and anion exchange (AE) described below are implemented in a continuous ion exchange (CIX) instrument system. The system used is a continuous operation in which there are multiple solid media chambers and multiple feed and discharge ports to / from the system that allow continuous solution feed and discharge. The system is such that the ports can be configured in a variety of ways, and once operational, solid media chambers can be transferred from one port or area to another without any interruption in the process flow.

[0021] In embodiments, an example of a type of CIX system includes the Calgon ISEP system (U.S. Patent No. 4,522,726), developed in the early 1980s. In this system, there is a fixed inlet and outlet distributor arrangement that directs fluids into and out of the system. There are multiple resin chambers mounted on a rotating table that moves the chambers from one area to the next. Another example would be an IONEX unit with a modified inlet / outlet fluid distribution arrangement that allows the resin chambers to remain stationary and moves fluid from one chamber to the next via a modified distribution system, providing a sample response similar to that in systems that utilize a rotating platform to move the chambers. These types of systems are essential for performing the multiple steps required to carry out this process.

[0022] More conventional types of ion exchange systems, such as fixed-bed units, which utilize manifolds for fluid distribution, are not flexible enough and are limited in the number of process steps that can be performed from a practical standpoint. Similarly, so-called semi-continuous ion exchange systems, such as "pulsed-bed" units, in which resin is periodically pulsed from one section of the unit to another, do not allow for truly continuous fluid flow and operational response. The nature of the process is such that multiple steps need to be performed without interruption, and the overall complexity of the ion exchange equipment system needs to be minimized. Truly continuous systems, such as those mentioned, meet this requirement.

[0023] Additionally, in the apparatus and processes described herein, the source of uranium, e.g., a phosphate source, can be returned to the phosphate facility. The apparatus and processes described herein include regeneration of the media using a regenerative chemical or combination of chemicals.

[0024] Furthermore, in the case of CIX, since the solid media (i.e., resin or equivalent material) does not have any solubility in the source of uranium, there is no need for any additional post-treatment of the solid media used in the ion exchange column. In addition, the uranium contained in the solid media is subsequently removed in the regeneration step of the process described herein. (Single Cycle Continuous Ion Exchange (CIX) Apparatus and Process)

[0025] The processes for recovering uranium described herein include single-cycle CIX apparatus and processes in which a solid contact medium is used to extract uranium from a source of uranium in a single CIX cycle. An exemplary embodiment of a single-cycle CIX apparatus and process is shown in FIG.

[0026] In an embodiment, the single-cycle CIX device includes the following major systems (ports): a pre-treatment system, which may include uranium source cooling and uranium source filtration and / or purification; Primary continuous contact (or primary CIX) systems, which contain the primary CIX system along with the systems required for the preparation of the primary pretreatment and regeneration solution (of the primary CIX system) and the peripheral equipment normally associated therewith, e.g., surge tanks, aqueous ammonia preparation, ammonium carbonate preparation (which is the primary regeneration solution), water wash feed systems, and the like; gradient elution and / or resin crowding systems (subports or subsystems), which may be part of the primary continuous contact system, for further removal of contaminants from the uranium source; A primary regenerant solution evaporation system, required to concentrate the primary regenerant solution and reduce the pH by decomposing excess ammonium carbonate; a uranyl precipitate filtration, washing, and digestion system in which the precipitated uranyl material is filtered, washed, and then digested with an acid solution to decompose the uranyl compounds and produce an acidified uranyl salt solution; an acidified uranyl salt solution precipitation (uranium precipitation) system in which an acidified uranyl salt solution is pH adjusted and soluble uranium is precipitated as an insoluble uranyl compound; A precipitated uranium washing and calcination system in which the insoluble uranyl compounds are washed, followed by drying and calcination of the uranyl compounds to produce a form of uranium, e.g., uranium oxide.

[0027] The single-cycle CIX process may also include uranium storage and automated packaging systems and steps, which are standard operations and will not be described in detail here. The single-cycle CIX process uses a single-cycle CIX device to recover uranium. The single-cycle CIX process is described below.

[0028] Pretreatment System and Process: A pretreatment system (and process) is not required, but can be used to remove suspended solids from the uranium source to minimize the accumulation of solids within the system. If the uranium source does not contain suspended solids, a pretreatment system (process) is not necessary. When phosphoric acid is used as the uranium source, a pretreatment system is used in the CIX process to remove suspended solids from the phosphoric acid. The uranium source is treated in a purification system to remove suspended solids in the source to a specific target level or below approximately 1,000 ppm. The purified source is then treated in an abrasive filtration system to reduce trace solids to levels below 100 ppm. It is important to note that, unlike fixed-bed ion exchange or solvent extraction systems, a certain level of solids is tolerable in the CIX process because there are routine, and sometimes frequent, "cleaning" steps within the CIX operation itself. The incoming uranium source (1) can be cooled and subsequently processed to remove suspended solids and trace color bodies. The solids can be returned to the original source. For example, solids from a phosphoric acid source (a source of uranium) can be returned to the phosphoric acid facility. Cooling systems are optional and can be site specific.

[0029] In an embodiment, pretreating the uranium source in a pretreatment system involves adding activated clay to the phosphoric acid from the gypsum / phosphate separation filter, followed by the addition of a flocculating material to solidify the solids, and the resulting mixture is sent to a clarification (settling) system. The clarified acid is then processed in a polishing filter to remove any remaining trace solids. Typically, activated clay is used, but other coagulation materials, such as activated silica, activated carbon powder, and the like, may also be used in place of activated clay. An organic flocculant is added to enhance the clarification of the solids. The primary function of the addition at this point is to enhance the coagulation of suspended solids in the feed source and to assist in enhancing the eventual settling of the solids from the liquid.

[0030] In an embodiment, the pretreatment system (process) includes systems (processes or steps) for clay addition, flocculant addition, and purification, followed by a system (process or step) for abrasive filtration, all of which are for the removal of solids from the uranium source.

[0031] Primary Continuous Contact (or Primary CIX) System: The primary CIX system (and process) performs two steps: an ion exchange extraction step to remove the target species, in this case uranium, and solid media regeneration. A uranium source (4), optionally a pretreated uranium source, first enters the primary CIX system, where it is contacted with a continuous system containing a suitable primary solid media. As the uranium source passes through the primary solid media, soluble uranium is transferred from the source to the solid media. The mechanism may be ion exchange transfer, and the uranium may be in cationic form as it is extracted from the source and transferred to the solid media. The uranium source (5), now depleted in uranium, can then be returned to the plant. As an example, the uranium source could be a phosphoric acid source that is returned to a phosphoric acid plant after uranium transfer to the primary solid media. Note that there may be some dilution of the source material, and therefore an evaporation unit may be included to remove small amounts of water from the source material. The uranium-loaded primary solid media is first washed with process water (7) to remove contaminating source solution from the resin. It is then regenerated by treatment with an alkaline carbonate solution (6) to convert the uranium to anionic uranyl carbonate complexes, which migrate from the solid media to the solution phase. The treatment then results in a regenerated primary solid media and a uranium-loaded primary regeneration solution (9) containing the anionic uranyl carbonate complexes. In an embodiment, the solid media in the primary CIX system is an ion exchange media.

[0032] The gradient elution or resin crowding system (and process), described in detail below, is a subsystem (sub-process) of the primary CIX system.

[0033] The primary solid medium for extracting uranium from a source can be any material that chelates or complexes uranium from the source. Primary solid medium includes chelating or complexing cation exchange (CE) media. As explained above, the primary solid medium removes uranium from the source in cationic form. The primary solid medium can be a primary CIX resin. Examples of useful resins and / or equivalent materials for the primary solid medium include: -LEWATIT® TP 260 TM Weakly acidic CE resins with chelating aminomethylphosphonic acid groups for the selective recovery of transition heavy metals, such as (Lanxess, Maharashtra, India); -AMBERLITE IRC-747 TM Aminophosphonic chelating resins such as Dow; Rohm & Haas, Philadelphia, PA) -S-930 TM Macroporous polystyrene-based chelating resins with iminodiacetic acid groups designed for the selective recovery of heavy metal cations, such as Purolite resin (Bala Cynwyd, PA); A composition or material comprising an agent having a chelating group, functionality, or moiety that binds uranium, such as an iminodiacetic acid group, an aminomethylphosphonic acid group, an aminophosphonic group, or a similar chelating functionality or moiety. Optionally, the composition or material comprises a bead, wire, mesh, nanobead, nanotube, nanowire, or other nanostructure, or a hydrogel. The agent can also be a non-resinous solid or semi-solid material.

[0034] In embodiments, the primary solid medium can be any resin or equivalent material containing one or more chelating groups, functional groups, or moieties that bind uranium from a source. In embodiments, the chelating groups, functional groups, or moieties bind uranium with high affinity from phosphoric acid. Examples of one or more such groups or moieties include iminodiacetic acid groups, aminomethylphosphonic acid groups, and aminophosphonic groups.

[0035] Prior to regeneration, the primary solid media is pretreated. The uranium-loaded primary solid media from the primary contacting step is washed with a small amount of water (7) and then transferred to the regeneration pretreatment step of the primary CIX process. During this portion of the primary CIX process, the uranium-loaded primary solid media is contacted with a small amount of alkaline carbonate solution (8) exiting the regeneration subsystem (of the primary CIX system) to prepare the primary solid media for regeneration. The alkaline carbonate solution (8) is part of the uranium-loaded regeneration solution that is recycled. The spent pretreatment solution is combined with the uranium-loaded primary regeneration solution (9) exiting the system.

[0036] Pretreatment of the primary solid media can also use a portion of the uranium-loaded primary regeneration solution that initially exits the regeneration system. This initial solution has a low uranium content and effectively neutralizes any residual acid in the primary solid media. This is important so that when the primary solid media enters the regeneration stage, there is no residual acid present that could react with the carbonate solution and reduce its pH.

[0037] Additionally, if any uranium is present in the pretreatment solution, this uranium will be reloaded onto solid media prior to its entry into the regeneration system, which has the added effect of allowing a level of uranium separation from contained contaminants by crowding the ion exchange sites with uranium.

[0038] It has also been discovered that by operating a portion of the pretreatment step of the primary CIX process in upflow mode, the primary solids media can be expanded between cycles. This expansion allows for periodic cleaning of the solids media, enabling the CIX equipment to handle much higher levels of solids than either fixed-bed or alternative solvent extraction systems. Any solids that accumulate within the system are then washed out of the system and transferred to a spent pretreatment solution storage area, where the solids are then disposed of. In embodiments, the initial pretreatment solution exiting the upflow section of the CIX may contain solids and be transferred to a spent pretreatment solution storage area. The solids can be disposed of as is, or the spent pretreatment solution is filtered to discard the solids and retain any uranium in the spent pretreatment solution.

[0039] After the regeneration pretreatment step, the pretreated primary solid media is contacted with an alkaline carbonate solution (6) to remove uranium and return the primary solid media to its extracted form. In this step, the alkaline carbonate solution converts uranium to an anionic (extracted form), i.e., anionic uranyl carbonate complex, which has no affinity for the primary solid media. The uranium thus transfers from the primary solid media in its extracted form to the alkaline solution phase, forming a uranium-loaded primary regeneration solution (9). The resulting regeneration solution (9) is then transferred to an evaporation system (primary regeneration solution evaporation system) for concentration of the anionic uranyl carbonate solution. The concentration of uranium in the primary regeneration solution (9) is significantly increased because the resulting volume of the primary regeneration solution is significantly less than the source of uranium loaded onto the solid media.

[0040] The regenerated primary solid media is washed with water before being returned to the primary CIX process.

[0041] In embodiments, suitable alkali carbonate solutions include ammonium carbonate, sodium carbonate, potassium carbonate, and the like. Selection of an appropriate solution is based on compatibility with the overall plant and process. In embodiments, ammonium carbonate is used as the alkali carbonate because it decomposes in the downstream evaporation / decomposition process to produce ammonium uranyl tricarbonate (AUT), which will reduce the pH of the loaded regeneration solution and thus enable uranium precipitation. It is important that the pH during the regeneration step be above a minimum value. In embodiments, the pH of the uranium-loaded primary regeneration solution is above about pH 9.0. If the pH falls below the minimum value, the uranium in the uranium-loaded primary regeneration solution may be reloaded onto the primary solid media. The minimum value depends on the alkali carbonate solution selected. As an example, an ammonium carbonate solution has a pH within the range of about pH 9.8 to about pH 10.5 due to the addition of ammonium, which is acceptable for this process.

[0042] In an embodiment, when the alkaline carbonate solution (6) used to remove uranium from the primary solid medium and form the anionic uranyl complex is ammonium carbonate, the anionic uranyl complex formed is ammonium uranyl tricarbonate, and the resulting uranium-loaded primary regeneration (9) solution comprises an ammonium uranyl tricarbonate solution.

[0043] Primary Regenerant Solution Evaporation System and Process: In this system (and process), the anionic uranyl carbonate solution is concentrated by evaporation. In an embodiment, the uranium-loaded primary regenerant solution (9) is heated in an evaporation system using indirect steam (10) to concentrate the AUT, decompose excess alkali carbonate, and reduce the pH of the solution. In an embodiment, the alkali carbonate solution is ammonium carbonate, and therefore the primary regenerant solution (9) containing the AUT is heated in an evaporation system using indirect steam to concentrate the AUT, decompose excess ammonium carbonate, and reduce the pH of the solution via the release of ammonia from the solution. As the pH is reduced, the solubility of uranium is reduced, which results in the formation of a uranyl precipitate. The alkali component resulting from the decomposition, e.g., ammonia (11B), is recovered and recycled, and the resulting solution is combined with the dilute alkali carbonate stream (11A). This allows for a high degree of recycling within the system and minimization of any resulting spent solution. Although other alkali carbonates can be used, ammonium carbonate is preferred because the properties of the resulting AUT are such that upon heating, the ammonia component decomposes and is released from solution, resulting in a decrease in pH and a decrease in the solubility of uranium in the solution. This is an important factor with AUT systems, as heating and evaporation will decompose the AUT. Other alkali carbonate systems, such as sodium and potassium carbonate, can also be used in conjunction with a reduction in the pH of the uranium-loaded primary regeneration solution (9), which requires the use of some form of acid to effect uranyl precipitation.

[0044] The primary regenerant solution evaporation system also includes a condenser to recover decomposed compounds, such as ammonia, from the regenerant solution and allow for recycling of the compounds.

[0045] Uranyl Precipitate Filtration / Washing / Digation System and Process: In this system (and process), uranyl precipitate (11) is first filtered and then washed with a small amount of water (12) to form a filter cake. The washed filter cake is then digested with acid (13) to dissolve the uranium and produce an acidified uranyl salt solution. Acids that can be used to digest the filter cake include sulfuric acid, nitric acid, hydrochloric acid, and equivalents. Organic acids such as acetic acid, glycolic acid, and equivalents can also be used, but in a typical recovery context, these organic acids are impractical and expensive. An important aspect of the process described herein is the ability to use acids that are most likely to be present in other operations in the phosphoric acid production process to minimize the introduction of new materials to the overall plant. As an example, if the phosphoric acid source facility uses H2SO4, sulfuric acid is used. From a production volume perspective, the majority of the world's phosphoric acid plants use H2SO4 as the digestion medium for phosphate rock. The resulting acidified uranyl salt solution (14) is then transferred to a precipitation system (Acidified Uranyl Salt Solution Precipitation System) for uranium precipitation. The lower pH, alkali carbonate-containing, dilute solution can be recycled (11A) to the primary CIX system and combined with the recovered alkali or anion components (11B) for reuse.

[0046] In this system, there is a filtration subsystem for filtering the uranyl precipitate, a washing system for washing the uranyl precipitate to form a filter cake, and a digestion system for digesting the filter cake with acid to dissolve the uranium and produce an acidified uranyl salt solution.

[0047] Acidified Uranyl Salt Solution Precipitation System and Process: In this uranium precipitation system (and process), an acidified uranyl salt solution (14) is combined with an alkaline solution (15), such as ammonium hydroxide, to increase the pH of the solution from about pH 2.5 to about pH 7.0, or from about pH 3.5 to about pH 6. After pH adjustment, a uranium precipitant (16), such as hydrogen peroxide, is added to form a uranyl peroxide precipitate or slurry (17). The uranyl precipitate or slurry is then transferred to a washing and calcination operation (precipitated uranium washing and calcination system).

[0048] Other alkaline solutions that may be used include sodium hydroxide, potassium hydroxide, and sodium or potassium carbonate.

[0049] While hydrogen peroxide is the preferred precipitant for producing high-quality uranium oxide, other precipitants can also be used. For example, ammonium hydroxide, ammonium carbonate, sodium hydroxide, sodium carbonate, or potassium hydroxide can be used as precipitants. These precipitants can be used by increasing the pH of the solution to 7 or above. As an example, the use of ammonium hydroxide will result in the formation of ammonium biuranate compounds at higher pHs, which may contain higher levels of impurities that need to be removed. Also, a preferred uranium compound is uranium oxide, which is formed using hydrogen peroxide as a precipitant. Other forms of uranium formed using other precipitates have limited uses other than for power and defense.

[0050] Precipitated Uranium Washing / Caustic System and Process: In this system (and process), as the uranyl precipitate (17) enters this process step, a small amount of a pH adjusting reagent (18) is added to adjust the pH of the precipitate. If the pH of the precipitate is low, e.g., below pH 2, an alkaline solution can be used for adjustment. If the pH is too high, e.g., above pH 5, a small amount of an acidic solution can be added. An example of an alkaline solution for increasing the pH includes ammonium hydroxide, and an example of an acidic solution for decreasing the pH includes sulfuric acid.

[0051] The mixture is then clarified, and the thickened uranyl precipitate is washed with a small amount of water (19). The uranyl solids are then centrifuged, and the recovered uranyl solids are transferred to a dryer / calciner system where they are decomposed to produce a uranium oxide product (21). Optionally, the process as described herein can further include separating the uranyl precipitate from the solution phase by settling, filtration, centrifugation, or a similar procedure, and then washing the uranyl precipitate with water. Washing can include washing the uranyl precipitate on a filter or repulping the uranyl precipitate with water, followed by settling, filtration, centrifugation, or a similar procedure, and optionally further washing the uranyl precipitate with water to remove most of any entrained secondary solution (without uranium) via additional filter washing, washing in a centrifuge, or optional additional repulping with water, followed by settling.

[0052] In embodiments, the precipitant used is hydrogen peroxide, and thus the uranyl precipitate formed is uranyl peroxide (UO42H2O). The processes described herein optionally include separating the uranyl peroxide from the solution phase by settling, filtration, centrifugation, or the like, and then washing the uranyl peroxide with water. The processes described herein further include drying the uranyl peroxide in a dryer / calciner system to form a dry solid material. In the dryer / calciner system, the uranyl peroxide is heated to a temperature sufficient to decompose or calcinate the uranyl peroxide and form a uranium oxide compound, e.g., U3O8.

[0053] It should be noted that the precipitated uranium at this stage is a uranyl peroxide compound that can be washed and dried without calcination to produce a dry U-peroxide material, if desired. Typically, however, the material is calcined to produce uranium oxide (U3O8) to produce a commercial standard product.

[0054] The spent solution from washing the uranyl precipitate is collected and filtered, and in an embodiment, the spent solution is recycled to upstream processes to minimize the overall plant aqueous spent solution volume (20).

[0055] In an embodiment, the calcined oxide product (U3O8) is lightly crushed and then dumped and loaded into drums for storage and shipping. An included drum loading system can be used to minimize the potential for dust generation. Dual-cycle continuous ion exchange (CIX) systems and processes

[0056] The uranium recovery processes described herein also include dual-cycle CIX apparatus and processes, in which two separate solid contact media are used to extract uranium from a uranium source. An exemplary embodiment of a dual-cycle CIX apparatus and process is shown in FIG. 2.

[0057] In an embodiment, a dual cycle CIX device for uranium recovery can be divided into the following major systems (ports): A pre-treatment system, which may include acid cooling of the uranium source and filtration and / or purification of the uranium source; Primary continuous contact (or primary CIX) systems, which contain the primary CIX system along with the systems required for the preparation of primary pretreatment and regeneration solutions (of the primary CIX system) and the peripheral equipment typically associated with them, e.g., surge tanks, regeneration solution preparation (e.g., ammonium carbonate), regeneration pretreatment solution preparation (e.g., ammonium hydroxide), and the like; Gradient elution and / or resin crowding systems (subports or subsystems), which may be part of the primary continuous contact system, for further removal of contaminants from the uranium source; A secondary continuous contact (or secondary CIX) system containing a secondary CIX system along with the systems required for the preparation of a secondary pretreatment regenerant solution (for the secondary CIX system) and the peripheral equipment normally associated therewith as discussed above; A gradient elution and / or resin crowding system (subport or subsystem), which may be part of a secondary continuous contacting system, for further removal of contaminants from the uranium source; a secondary regenerated solution precipitation system in which the secondary uranium-loaded regenerated solution is pH adjusted and soluble uranium compounds are precipitated as insoluble uranyl compounds; A precipitated uranium washing and calcination system in which the insoluble uranyl compounds are washed, followed by drying and calcination of the uranyl compounds to produce some form of uranium, such as uranium oxide.

[0058] The dual cycle CIX process can also include uranium storage and automated packaging systems and steps, which are standard operations and will not be described in detail here. The dual cycle CIX process uses a dual cycle CIX device to recover uranium. The dual cycle process is described below.

[0059] In embodiments, at least one of the primary CIX system or the secondary CIX system includes a gradient elution or resin crowding system. In embodiments, both the primary CIX system and the secondary CIX system include a gradient elution or resin crowding system.

[0060] Pretreatment System and Process: The pretreatment process is described above for single cycle CIX and therefore will not be repeated here.

[0061] Primary Continuous Contact (or Primary CIX) System: Similar to the single-cycle CIX primary CIX system (process), the dual-cycle CIX primary CIX system (and process) implements two steps: an ion exchange step and solid media regeneration. The uranium source (4), optionally a pretreated uranium source, first enters the primary CIX system, where it is contacted in a continuous system containing a suitable primary solid media. As the uranium source passes through the primary solid media, soluble uranium is transferred from the source to the solid media. The mechanism can be ion exchange transfer, and the uranium can be in cationic form when it is extracted from the source and transferred to the solid media. The uranium source (5), now depleted in uranium, can then be returned to the plant. As an example, the uranium source can be a phosphoric acid source that is returned to the phosphoric acid plant after uranium transfer to the solid media. The uranium-loaded primary solid media is then regenerated with an alkaline carbonate solution (9) to convert the uranium to anionic uranyl carbonate complexes, producing a regenerated primary solid media and a uranium-loaded primary regeneration solution containing anionic uranyl carbonate complexes.

[0062] A gradient elution or resin crowding system (and process), described in detail below, can be included as a subsystem (sub-process) of the primary CIX system.

[0063] The primary solid medium for extracting uranium from a source can be any material that chelates or complexes the uranium from the source and is described above under Single Cycle CIX, and therefore, that information will not be repeated here.

[0064] Prior to regeneration, the primary solid media is pretreated. The uranium-loaded primary solid media is washed with a small amount of water (6) contained therein and then transferred to the regeneration pretreatment step of the primary CIX process. During this portion of the primary CIX process, the uranium-loaded primary solid media is contacted with an alkaline pretreatment solution (7) to prepare the media for regeneration. The alkaline pretreatment solution used during the regeneration pretreatment step is a weak alkaline solution, such as ammonium hydroxide, which neutralizes any remaining free acid in the solid media. The spent alkaline pretreatment solution (8) can be sent to a wastewater system or recycled for other uses. Other weak alkaline solutions that can be used include weak sodium hydroxide, weak potassium hydroxide, and the like. However, weak ammonium hydroxide is preferred due to its compatibility with the CIX process and its common use in many phosphate complexes, especially where ammonium fertilizer is produced.

[0065] Following pretreatment of the primary solid media, the uranium-loaded primary solid media is regenerated using an alkaline carbonate solution (9) to convert the uranium to an anionic uranyl carbonate complex, which does not have any affinity for the primary solid media, and is added to the regenerated primary solid media to produce a uranium-loaded primary regeneration solution (10). Examples of alkaline carbonate solutions include ammonium carbonate, sodium carbonate, and potassium carbonate. The selection of an appropriate alkaline solution is based on compatibility with the overall plant and process. In an embodiment, the anionic uranyl carbonate complex is an ammonium uranyl tricarbonate complex when the alkaline carbonate solution is ammonium carbonate. As shown, the steps performed in the primary stage of the dual-cycle CIX process are essentially identical to the CIX operation in the single-cycle approach.

[0066] The uranium thus migrates from the primary solid media into the alkaline carbonate solution phase. The resulting uranium-loaded primary regenerated solution is a smaller volume compared to the volume of the uranium source used and contains a higher concentration of uranium in solution. The resulting uranium-loaded primary regenerated solution (10) is then transferred to the secondary CIX system. The concentration of uranium in the primary regenerated solution (10) is significantly increased because the resulting volume of the primary regenerated solution is significantly less than the uranium source loaded onto the solid media.

[0067] The regenerated primary solid media is washed with water before being returned to the primary CIX process.

[0068] As noted in the single cycle CIX process, it is important that the pH in the regeneration step be above a minimum value because if the pH falls below a certain level, the uranium in the primary regeneration solution may be reloaded onto the primary solid media. Information regarding the importance of pH during the regeneration step will not be repeated here.

[0069] Also, similar to the single-cycle CIX process, by operating a portion of the pretreatment in upflow mode, the primary solids medium can be expanded between cycles, which allows for periodic cleaning of the solids medium and allows the CIX process to handle much higher levels of solids than either fixed-bed or alternative solvent extraction systems. Any solids that accumulate within the system are then washed out of the system and transferred to a spent pretreatment solution storage area, and then ultimately the solids are disposed of. In embodiments, the initial pretreatment solution exiting the upflow section of the CIX may contain solids and be transferred to a spent pretreatment solution storage area. The solids can be disposed of as is, or the spent pretreatment solution is filtered to discard the solids and retain any uranium in the spent pretreatment solution.

[0070] Secondary Continuous Contact (or Secondary CIX) System and Process: In this system (and process), the uranium-loaded primary regenerant solution (10) is contacted with a secondary CIX solid media (second ion exchange system) utilizing a strong anion resin to extract uranium from the primary regenerant solution and load it onto the strong anion resin. The secondary regenerant solution is an acid other than phosphoric acid and can be an inorganic acid such as sulfuric acid (H2SO4), nitric acid (HNO3), hydrochloric acid (HCl), and the like. H2SO4 is the preferred acid in this case because it is used in most (but not all) phosphate facilities as the acid source for digestion of phosphate rock to produce so-called wet process phosphoric acid. Secondary CIX systems can be significantly smaller than primary CIX systems, and different solid media can be used. However, the principles of operation are similar to those used in primary CIX systems.

[0071] The uranium (anionic uranyl carbonate) contained in the primary regenerant solution (10) is transferred to a secondary solid medium. The secondary solid medium comprises a strong anionic ion exchange resin (AE) medium or equivalent material. Therefore, the secondary solid medium has a high affinity for the anionic uranyl carbonate complexes in the primary regenerant solution (10). In an embodiment, the dilute primary regenerant solution (11) from the secondary system is recycled to the greatest extent possible.

[0072] Strong anion exchange resins are commercially used to treat conventional uranium-bearing solution sources, such as those produced in some popular in-situ uranium leaching processes. In this disclosure, the use of AE is incorporated into a novel process for the recovery of uranium from phosphoric acid. AE is used after the uranium has been removed from the phosphoric acid and transferred to another solution phase, such as ammonium carbonate. A "traditional" ion exchange approach, i.e., the direct use of conventional cation or anion exchange resins with phosphoric acid, is impractical due to the highly complex nature of uranium in phosphoric acid media. Therefore, more powerful techniques, such as complexing or chelating ion exchange resins, are required to remove uranium from phosphoric acid. Once the uranium has been transferred to a more "traditional" solution phase, such as ammonium carbonate, approaches based on some modifications of current techniques, such as anion exchange, can be used. While some of the chemistry for the second CIX in a dual-cycle CIX system is similar to conventional methods, necessary adaptations still exist, such as how secondary extraction and subsequent regeneration are incorporated into the overall treatment system to have an integrated process approach.

[0073] A gradient elution or resin crowding system (and process), described in detail below, can be included as a subsystem (sub-process) of a secondary CIX system.

[0074] The secondary solid medium can be any strong anionic ion exchange material that extracts anionic uranium from the primary loaded regeneration solution (10) using a corresponding ion exchange between an anion, such as sulfate (SO4) anion, on the regenerated anionic resin for an anionic uranium complex, such as uranyl carbonate anion, in the primary loaded regeneration solution (10). The secondary solid medium should be a strong anionic ion exchange material. Examples of resins or equivalent materials for the secondary solid medium include: -LEWATIT® K 6267 TMStrongly basic anion exchange resins with type II quaternary ammonium functional groups for selective recovery of anionic heavy metal complexes, such as (Lanxess, Maharashtra, India); - Strong anionic resins established in the traditional uranium recovery industry, such as Dow-Rohm / Haas 21K, -PUROLITE A-600 TM Strongly basic anion exchange resins with type I quaternary ammonium functional groups for selective recovery of anions, such as (Purolite, Bala Cynwyd, PA); -A composition or material containing a drug having one or more chelating groups, functionalities, or moieties that bind anionic uranyl complexes. As an example, the chelating groups, functionalities, or moieties include Type I or Type II quaternary ammonium functionalities. Optionally, the composition or material includes beads, wires, meshes, nanobeads, nanotubes, nanowires, or other nanostructures, or hydrogels. The drug can also be a non-resinous solid or semi-solid material.

[0075] In embodiments, the secondary solid medium can be any resin or equivalent material containing Type I or Type II quaternary ammonium functional groups.

[0076] In an embodiment, the secondary solid medium is sulfuric acid (SO4) -2 groups, which are converted to strong anionic anions, e.g., (SO4) groups, via migration of the anionic groups from the resin (solid) phase to the liquid phase in exchange for anionic uranyl carbonate species originally present in the primary loading regeneration solution from the primary CIX system. -2 Uranium extraction is carried out via anion exchange of HSO. Note that other strong anionic groups, such as nitrate (NO) or chloride (Cl), can also be used. However, the preferred material is HSO, as this is generally the most common acid solution used in the phosphoric acid industry.

[0077] The loaded secondary solid media then undergoes pre-regeneration treatment by washing with water (12). The washed media is then regenerated by contact with a secondary regeneration solution (13), which is a strong acid such as H2SO4 but diluted with water to produce a less concentrated acidic solution for use as a regeneration material. The uranium-loaded secondary regeneration solution (14), now containing a high concentration of uranium, is then transferred to a uranium-loaded secondary regeneration solution precipitation system. The regenerated secondary solid media is washed with water before returning to the secondary CIX process. After the water wash, the solid media is washed with a small amount of weak ammonium hydroxide (not shown) to neutralize any traces of H2SO4 that may remain in the media. This is done so that the pH of the resin media entering the secondary loading or extraction section of the CIX is within the same range as that of the loaded regeneration solution obtained from the primary CIX system. In this way, uranyl carbonate is maintained as a strong anion in the primary solution (10) fed to the secondary cycle.

[0078] At initial start-up, the uranium-loaded secondary regenerated solution (14) may not be of sufficient purity. The initial uranium-loaded secondary regenerated solution (14) can be recycled and / or stored. Under normal conditions, even if the plant is shut down, once the process is underway, there will be purified solution available for storage and use in restarting the plant.

[0079] The use of an acidic secondary regeneration solution enhances secondary regeneration by ensuring that all of the uranium is reconverted to a cationic form that does not have any affinity for the anionic secondary solid media. In embodiments, the secondary regeneration solution (13) can be dilute sulfuric acid, dilute nitric acid, dilute hydrochloric acid, or an equivalent solution. The acid selected for the secondary regeneration solution depends on the acid source used for phosphoric acid production and whether any unique circumstances exist associated with the particular uranium recovery operation. In embodiments, when the source of uranium is also a source of phosphoric acid, sulfuric acid is used due to its compatibility with existing phosphoric acid operations. In the present system, acidic materials are used for regeneration. However, other regeneration solutions have also been used in other applications. Typically, these would be neutral salts of strong acid materials. These would include salts such as ammonium sulfate, ammonium nitrate, ammonium chloride, sodium chloride, sodium nitrate, sodium sulfate, potassium salts, and the like. For uranium recovery from phosphoric acid systems, H2SO4 is the preferred regeneration solution for the secondary CIX anion exchange.

[0080] In an embodiment, when ammonium carbonate is used as the primary regenerant solution in the primary CIX process and sulfuric acid is used as the secondary regenerant solution in the secondary CIX process, the cationic form of uranium in the uranium-loaded secondary regenerant solution is an acidic ammonium uranyl sulfate solution.

[0081] In the past, there have been concerns about using low pH solutions for the regeneration of anionic media because the residual carbonate solution remaining in the media after the secondary charge would react with the acid, decompose, form salts, and release carbon dioxide within the media bed. However, by implementing the CIX approach as described herein, a portion of the regeneration system can be operated in upflow mode; by operating the initial regeneration contact in this mode, there is a level of decomposition, and the released carbon dioxide actually assists in the expansion of the media bed, allowing for a level of media cleaning at the start of the secondary regeneration stage.

[0082] The use of upflow mode is discussed above with respect to pretreatment regeneration of primary CIX processes. In embodiments, the CIX processes described herein include the use of upflow mode, which can be operated with or without air assistance, to assist upwardly flowing liquid in expanding the media bed and loosening accumulated solids so that they can be washed from the solid media. In the case of secondary CIX processes, the release of carbon dioxide within the media bed allows for "in situ" gas formation and subsequent solid media refining.

[0083] The regenerated secondary solid media can be treated with water to remove entrained acidic regeneration solution. The secondary solid media can be further post-treated with an alkaline solution (not shown) to neutralize any residual acid in the media before re-entry into the secondary CIX process. Typically, this alkaline solution will consist of weak ammonium hydroxide, similar to that used in the primary CIX system following the post-load water wash to remove traces of phosphoric acid from the loaded resin prior to the ammonium carbonate regeneration step.

[0084] Secondary Regenerated Solution Precipitation System and Process: In this precipitation system (and process), the uranium-loaded secondary regenerated solution (14) is combined with an alkaline solution to increase the pH of the uranium-loaded secondary regenerated solution to about pH 2.5 to about pH 7.0 or about pH 3.5 to about pH 6. After pH adjustment, a precipitant (16) is added to form a uranyl precipitate or slurry. The uranyl precipitate or slurry is then transferred to a precipitated uranium washing and calcination system for decantation, washing, and calcination.

[0085] Examples of alkaline solutions that can be used to increase the pH of the uranium-loaded secondary regeneration solution include ammonium hydroxide, potassium hydroxide, and sodium hydroxide. Ammonium hydroxide is the preferred alkaline because it is generally used elsewhere in the process and can therefore be configured at a single point for use throughout the process. The alkaline solution can have a concentration of 10% to 30%. Optionally, the alkaline solution has a pH greater than 10 in its solution form.

[0086] An example of a precipitating agent includes hydrogen peroxide. In an embodiment, when hydrogen peroxide is added to a pH-adjusted uranium-loaded secondary regeneration solution, the uranyl precipitate formed is uranyl peroxide. Hydrogen peroxide forms uranyl peroxide, allowing excess peroxide to be present in solution, and is added in an amount sufficient to ensure complete uranyl peroxide precipitation. It is important to note that HO is used as the precipitating agent because uranyl peroxide will precipitate from the uranium-bearing solution at a slightly acidic pH. For example, with pH adjustment of the loaded secondary solution to pH 3-4, the peroxide material will precipitate. Equally important, many of the other impurities that may be present in the secondary loading solution do not precipitate under acidic conditions, and therefore, they can remain in the solution phase. In this way, further uranium purification is achieved.

[0087] Other methods exist for precipitating uranium from the secondary charge solution, which involve the addition of an alkaline solution, such as ammonium hydroxide, to raise the pH of the solution to a level above 7, forming a weakly alkaline solution. In such cases, uranium can be precipitated as ammonium uranyl diuranate. Sodium hydroxide or potassium hydroxide can also be used for alkaline precipitation. These precipitants can be used to increase the pH of the solution to 7 or above. As an example, the use of ammonium hydroxide will result in the formation of an ammonium diuranate compound at a higher pH, which may contain higher levels of impurities that would need to be removed.

[0088] Also, the preferred product is uranium oxide, formed using hydrogen peroxide as the precipitant. Thus, the use of hydrogen peroxide precipitation is a preferred means of providing minimal impurities, as precipitation occurs under mildly acidic conditions.

[0089] Precipitated Uranium Washing / Caining System and Process: In this system (and process), for example, pH adjustment, washing, and calcination of uranyl precipitate to form uranium oxide compounds or uranium is discussed under the single-cycle CIX process. Therefore, the information will not be repeated here.

[0090] The end product would be uranium oxide, similar to U3O8 produced from conventional uranium recovery operations that use various uranium ores (not phosphate) as feedstocks.

[0091] Many parts of the dual-cycle and single-cycle CIX procedures, such as the acid sweep, most of the primary extraction, and the precipitation and drying sections through to the final product, can be the same. One major difference between the two processes is that in dual-cycle, there is a second CIX system, while in single-cycle, there is a single CIX system. In the single-cycle CIX process, the second CIX system is essentially replaced by the primary regenerant solution evaporation system and the differential treatment of the concentrated primary regenerant solution ((14) in each figure) to create the acidified uranyl solution, which is common to both processes. From there, the processes are virtually identical. Gradient Elution (GE) and Resin Crowding (RC) Systems and Processes

[0092] It has been found that some contaminants are loaded onto the solid media along with the uranium and are eluted away along with the uranium when the regeneration solution is applied in the regeneration stage. Thus, the uranium-loaded primary and secondary regeneration solutions often contain contaminants in addition to uranium. As an example, a source of uranium, such as phosphoric acid, may contain dissolved iron. A small portion of the iron can be co-extracted with the uranium onto the primary CIX chelating resin. Although the proportion of dissolved iron in the co-extracted acid is small, the starting amount of iron can be high, so there is still a good portion of the iron loaded onto the primary resin along with the uranium for uranium recovery.

[0093] This disclosure describes processes for further removal of contaminants to enhance the purity of recovered uranium obtained from single- and dual-cycle CIX processes. These processes include gradient elution (GE) and resin crowding (RC). The GE and RC processes remove contaminants prior to removal of uranium from the solid media, which reduces contaminants in the final uranium product and results in a higher quality uranium product. Both of these processes utilize the strong affinity of uranium for CIX media compared to contaminants, resulting in selective removal of contaminants from uranium.

[0094] Gradient Elution (GE) Systems and Processes: In GE systems (and processes), a weak solution of alkaline carbonate regeneration solution, in the case of a primary CIX system, or a dilute solution of acidic regeneration solution, as would be used for a secondary CIX system, is applied to the solid media during pretreatment. The selection of the appropriate acid or base solution depends on whether the solid media is a chelating or complexing cationic ion exchange (CE) media or anionic ion exchange (AE) media. In the case of AE media in a secondary CIX system, a dilute acidic solution is used to remove anions, non-uranium anions, from the media. The concentration of the acid solution will start at a value less than one-third that of the actual solution that will be used for resin regeneration and uranium removal. The pH will be slightly higher than the actual regeneration solution, by about one pH point. Non-uranium anions have a lower affinity for the AE media than the uranyl complexes bound to the AE media. Therefore, even with a dilute regeneration solution, many of the non-uranium ions can be removed from the strong anion resin. Regarding the uranium recovery process, the present system has discovered that uranium has some of the highest affinity for the resin compared to other ions present. Therefore, by initially treating the resin with a solution weaker than that required to remove uranium, some of the non-uranium ions can be removed. After initial treatment with the weakest acid solution, the process continues by applying dilute acid solutions of increasing strength to the AE medium, continuously removing non-uranium anions from the AE medium until a practical point is reached where additional acid treatment will begin to remove uranium along with any remaining impurity materials. The maximum allowable strength for the gradient solution material will depend on the actual operating conditions, but as a rough guide, the maximum strength can be estimated to be 40% of the actual strength of the acid that will be used for regeneration and uranium removal. These values ​​may vary but can be empirically determined and controlled.

[0095] There are various known methods for generating dilute acid gradient solutions of various strengths. Examples of dilute acid solutions that can be used with the AE media in GE include dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid. The acid selected depends on its compatibility with the rest of the process. In an embodiment, when the source of uranium is the source of phosphoric acid, sulfuric acid is the most suitable acid for the process and the overall system.

[0096] In the case of complexing or chelating cation exchange (CE) media (in a primary CIX system), a dilute base solution is used. In this case, the solution is prepared by diluting a portion of the primary alkaline regeneration solution (ammonium carbonate). The same process described above is used for the dilute base solution, including increasing the strength of the dilute base solution to remove non-uranium cations, which have a lower affinity for the CE media. Examples of dilute base solutions that can be used with CE media include dilute ammonium carbonate, dilute sodium carbonate, and dilute potassium carbonate. The base chosen depends on its compatibility with the rest of the process. In an embodiment, the alkaline solution is ammonium carbonate, since this is the solution that will be used for the primary regeneration step.

[0097] The single-cycle and dual-cycle CIX processes described herein can include a GE process in the primary and / or secondary CIX processes. In a single-cycle CIX process, the solid medium in the primary CIX process is a CE medium. Therefore, a dilute base solution is the appropriate solution to be used for gradient elution. Similarly, in a dual-cycle CIX primary CIX process, the solid medium is a CE medium, and therefore, the appropriate solution is also a dilute base solution. However, in a dual-cycle CIX secondary CIX process, the solid medium is an AE medium. Therefore, in a GE process, the appropriate solution to be used in conjunction with the AE medium is a dilute acidic solution.

[0098] The GE process is performed during the pre-regeneration step of the primary or secondary CIX media, after uranium has been loaded onto the primary or secondary CIX media and before regeneration of the primary or secondary CIX media. In an embodiment, GE is performed during the primary pre-regeneration step of the primary CIX process for both single-cycle and dual-cycle CIX processes. GE begins after the uranium-loaded CE media, i.e., the primary CIX media, is washed with a small amount of water. In an embodiment, during GE of the primary CIX process, an increased strength dilute base solution, such as a dilute carbonate solution, is used to remove non-uranium cations. The strength of the dilute base solution is increased until most of the contaminants are removed from the CE media, while uranium is left on the resin to be removed in the primary regeneration step. The dilute base solution includes a dilute ammonium carbonate solution, a dilute sodium carbonate solution, or a dilute potassium carbonate solution. In an embodiment, the dilute base solution is a dilute ammonium carbonate solution.

[0099] After removal of most of the contaminants, the CE media is ready for regeneration, which involves converting the uranium on the CE media to anionic uranyl carbonate using alkaline carbonate (primary regeneration solution), as discussed above.

[0100] The GE process can also be performed during the secondary regeneration pretreatment step of the secondary CIX process of the dual-cycle CIX process. Similar to the primary CIX process, GE can begin after the AE media loaded with uranyl carbonate complexes, i.e., the secondary CIX media, is washed with a small amount of water. In an embodiment, during the GE of the secondary CIX process, an increased strength weak sulfuric acid solution is used to remove non-uranium anions. The strength of the dilute sulfuric acid solution is increased until most of the contaminants are removed, but uranium is not removed in this stage and is left for removal in the regeneration step.

[0101] After removal of the majority of the contaminants, the AE media is ready for regeneration, which involves converting the uranium on the AE media to a cationic form using a secondary regeneration solution, i.e., a weak acid, as described herein.

[0102] In an embodiment, when ammonium carbonate is used as the primary regenerant solution in the primary CIX process and sulfuric acid is used as the secondary regenerant solution in the secondary CIX process, the cationic form of uranium in the uranium-loaded secondary regenerant solution is an acidic ammonium uranyl sulfate solution.

[0103] In an embodiment, the GE process is performed in either the primary or secondary CIX process of a dual cycle CIX process. In an embodiment, the GE process is performed in both the primary or secondary CIX process of a dual cycle CIX process. The use of the present technique in both cycles in a dual cycle system provides further assurance of contamination control.

[0104] In an embodiment, the GE system implementing the GE process includes several zones within the CIX system itself. In each zone, different strengths of acid or base can be applied to the CE or AE media to remove a portion of the contaminants. The GE system would be implemented before the actual regeneration step. Following the GE portion of the process, the solid media would enter the actual regeneration zone within the CIX system for removal of uranium from the solid media, which involves treatment of the solid media with an alkaline or acid regeneration solution and subsequent conversion of the solid media to the form required for return to the loading portion of the process. The GE system can include 1 to 50 zones. The GE system can include 1, 2, 3, 4, or 5 zones. The GE system can include 1 to 50 zones, 5 to 45 zones, 10 to 40 zones, 15 to 35 zones, 20 to 34 zones, 22 to 33 zones, or 24 to 32 zones. The number of zones used for GE will depend on the specific system and the extent of contamination control required.

[0105] Figure 3 shows an example of a GE system and process that includes zones and is used in conjunction with a secondary CIX process to remove anionic contaminants. A chamber containing an AE media (1) loaded with a uranyl carbonate complex (from the primary regeneration solution) enters zone X of the GE process. Note that the zones are referred to as X, X-1, etc. This convention was chosen to allow for focus on the GE step, regardless of the actual zone this may be in a commercial system. Depending on the process, there may be several zones, e.g., 24 to 32, for a given commercial unit. Therefore, rather than choosing zone numbers for exposition, a general approach was used. In some processes, zone X may actually be zone 24 in the specific case. In this case, zone X-1 would be zone 23. In another process, the zone numbers may be different. Therefore, the use of X, X-1, etc. eliminates the need for specific numbering. It is important to recognize that the resin chambers move from right to left in this example, i.e., from zone X to zone X-1, etc. The AE media (1) is contacted with a solution of sulfuric acid (2) whose acid strength is significantly weaker than that used for the actual removal of uranium from the resin. The weakest sulfuric acid solution passes through the resin, removing anions that have a lower affinity for the resin than the uranyl carbonate complexes. The spent weakest solution (3) is then discharged from the system.

[0106] The chamber containing the solid media is then transferred to section X-1. In section X-1, the resin is contacted with a medium-strength sulfuric acid solution (4). The strength of the solution is controlled so that additional contamination is removed from the resin, but again, the acid in this section is weaker than that required for the removal of uranium from the resin. The spent medium-strength sulfuric acid (5) is also discharged from the system.

[0107] Depending on how the uranium recovery equipment is integrated into the phosphoric acid complex, opportunities may exist to utilize these spent solutions in other operations within the overall phosphoric acid production facility. These are factors that can be advantageously employed to increase the economic attractiveness of the process for a particular phosphoric acid operation.

[0108] After the medium-strength sulfuric acid treatment, the chamber containing the solid media is then transported to section X-2. In this section, the regeneration solution used to countercurrently contact the solid media chambers in sections X-4 and X-3 is collected from section X-3 and sent to section X-2 for final regeneration contact. The uranium-loaded secondary regeneration solution exiting section X-2 is transported to a uranium-loaded secondary regeneration solution precipitation system (8). In sections X-2-X-4, the AE media is countercurrently contacted with the strongest sulfuric acid (6), which is sent from section X-4 to section X-3 and then to section X-2. This countercurrent contact approach is used to maximize the potential concentration of uranium in the uranium-loaded secondary regeneration solution (8) exiting the CIX system and provide efficient regeneration of the media using a minimal amount of fresh regeneration solution.

[0109] The regenerated AE media (7) is then transferred to a post-regeneration water wash step and finally returned to the secondary CIX system where it is again contacted with fresh primary charge regeneration solution taken from the primary CIX system.

[0110] The GE process allows for the treatment of primary or secondary media for selective removal of anions from the resin. As an example, by taking advantage of the affinity of various anions for the AE resin in a secondary CIX system, sulfuric acid of varying strengths can be used to separate contaminants from the AE resin before U is removed. As shown, the same process concept can be applied to a primary CIX system, except that in this case, an alkali carbonate solution, e.g., ammonium carbonate, is used instead of an H2SO4 solution. The operating concept is the same; the only difference is that in the primary system, an alkali carbonate gradient is used.

[0111] Resin crowding (RC) systems and processes: RC processes can be performed during the pre-regeneration step of the primary or secondary CIX media, after uranium has been loaded onto the primary or secondary CIX media and before regeneration of the primary or secondary CIX media. The single-cycle or dual-cycle CIX processes described herein can also include RC systems (and processes). In a single-cycle CIX process, RC can be performed during the pre-regeneration step of the primary CIX process. In a dual-cycle CIX process, RC can be performed during one or both of the primary and secondary pre-regeneration steps of the primary and secondary CIX processes.

[0112] In both the single-cycle and dual-cycle CIX primary CIX systems and processes, RC can be initiated after the uranium-loaded CE media (primary CIX media) is rinsed with a small amount of water. A portion of the uranium-loaded primary regeneration solution, either recycled / stored or the (low-purity) initial start-up uranium-loaded regeneration solution, is pH-adjusted using a dilute sulfuric acid solution. The pH adjustment converts the anionic complex uranium in the solution to a cationic form so that it has affinity for the CE media and can be reloaded onto it. The pH-adjusted solution (cloud solution) is applied to the CE media. Due to the affinity of uranium for the CE media relative to other ions present, the uranium in the cloud solution displaces non-uranium contaminants, resulting in the CE media being more fully loaded with uranium before regeneration. It is important to note that a relatively small pH reduction in the loaded primary regeneration solution will cause the uranium component to reload onto the primary CE media. This sensitivity was discovered during regeneration testing of the primary CE media using ammonium carbonate solution. If there had been a pH reduction in the regeneration solution, for whatever reason, the uranium would not have been removed from the CE media; rather, the uranium that was in the regeneration solution would have loaded back onto the CE media. This was a clear detriment to regeneration efficiency, but it did demonstrate the potential for slight pH adjustment to a portion of the primary loading regeneration solution to allow reloading onto the resin prior to full regeneration and a "cloud" from non-uranium ions on the CE media.

[0113] Examples of dilute acids used to reduce the pH of a portion of the primary loading regeneration solution (ammonium uranyl carbonate) to generate a small amount of cloud solution for RC in the primary CIX process include sulfuric acid, nitric acid, and hydrochloric acid. In an embodiment, sulfuric acid is used because it is most compatible with process systems that use phosphoric acid as a source of uranium. Upon addition of the dilute acid to a portion of the primary loading regeneration solution (ammonium uranyl carbonate), the pH of the solution is reduced to a target value. Typically, the loading regeneration solution has a pH in the range of 10.0 to 10.5. With slight acidification, the pH of the portion to be used for clouding is reduced to approximately 8.0 to 8.5. Under these conditions, the uranium contained therein is in a non-anionic form.

[0114] After crowding, the majority of the non-uranium contaminants have been removed and additional uranium has been reloaded onto the resin. The CE media is then ready for regeneration, which involves converting the uranium on the CE media to anionic uranyl carbonate using an alkaline carbonate (primary regeneration solution), as described herein.

[0115] RC can also be performed during the secondary regeneration pretreatment step of the secondary CIX process of the dual-cycle CIX process. Similar to the primary CIX process, RC can be initiated after the AE media loaded with uranyl carbonate complexes (secondary CIX media) is rinsed with a small amount of water. A portion of the uranium-loaded secondary regeneration solution (e.g., uranyl sulfate solution) from storage / reclamation of a previous cycle or from initial startup is pH-adjusted with a dilute base solution and applied to the AE media. The pH adjustment converts the uranium in solution to an anionic form so that it has affinity for the AE media and can be reloaded onto it. Due to the affinity of uranium for the media relative to other ions present, the uranium in the cloud solution displaces non-uranium contaminants, resulting in the AE media being more fully loaded with uranium before regeneration.

[0116] Examples of bases that may be used in the secondary CIX process include ammonium hydroxide, sodium hydroxide, and potassium hydroxide. In embodiments, ammonium hydroxide is used because it is compatible with the overall process system.

[0117] After "crowding" of impurities from the resin and replacement with uranyl anion complexes, the AE media is ready for regeneration, which involves converting the uranium on the AE media to its cationic form using a secondary regeneration solution, i.e., dilute sulfuric acid.

[0118] In an embodiment, an RC system implementing the RC process includes one or more zones. In each zone, the pH-adjusted load regeneration solution from either the primary or secondary CIX system is pH-adjusted and then applied to either the CE or AE media, depending on the CIX in which the RC is being performed, to remove contaminants. The pH-adjusted primary or secondary regeneration solution can be obtained from another zone, such as a later zone in the sequence of zones through which the chamber containing the CE or AE media passes during the regeneration process. Following the RC section of the CIX system before regeneration, the solid media chamber travels through a regeneration zone following the RC. The RC section for each CIX system, either CE or AE, can consist of any number of ion exchange zones, but typically the RC section will have one to five zones. The number of zones depends on the specific operating characteristics of the CIX, either CE or AE. Following the RC portion of the CIX, the "crowded" resin is treated in the regeneration zone of the CIX, where it is contacted with a selected regeneration solution. For this system, ammonium carbonate solution would be used for the CE and dilute sulfuric acid would be used for the AE.

[0119] FIG. 4 shows an example of an RC system and process that includes an area and is used in conjunction with a secondary CIX process to remove anionic contaminants. The secondary CIX (AE) medium is sulfuric acid (SO4). -2Uranium extraction is carried out via anion exchange with uranium. After washing, the AE media (1) loaded with uranyl carbonate complex (from the primary regeneration solution) enters section X of the RC process. The AE media (1) is contacted with the solution exiting section X-1, which is fed forward to section X. This, as mentioned above, provides countercurrent contact and increased efficiency with a minimal amount of solution used. The spent RC solution exiting section X (2) contains the majority of impurities.

[0120] The crowding solution, i.e., the solution exiting zone X-1, can be prepared by taking a portion of the uranium-loaded secondary regeneration solution exiting zone X-2 (6), adjusting it with a base (3) to raise its pH, and moving this solution forward to zone X-1. For this example, the base used is a solution of dilute ammonia because this material is compatible with the overall uranium regeneration operation. Ammonia is chosen for its convenience and ease of handling, although other bases such as sodium hydroxide, potassium hydroxide, and the like can also be used.

[0121] Due to the nature of uranium in the sulfate solution (initial uranium-loaded secondary regeneration solution), when the pH is increased slightly, the uranium again assumes anionic nature, which again has a higher affinity for the AE media than other anions (contaminants). As the AE media moves from Zone X to Zone X-2, the pH-adjusted solution contacts the AE media containing uranium and contaminants, and the anionic uranium in the pH-adjusted solution displaces non-uranium anions (contaminants) on the AE media because anionic uranium has a higher affinity for the AE media than non-uranium anions. The non-uranium anions are transferred to the solution phase. The pH-adjusted solution leaving Zone X-1 is transferred to Zone X, creating countercurrent contact.

[0122] The displacement or extrusion of non-uranium anions by uranium anions of higher affinity provides a "crowding" effect because, as the AE medium loading becomes fully loaded with different anions, the anions with the highest affinity for the AE medium will displace or crowd out the anions with lower affinities. These lower affinity anions then migrate to the solution phase. Because uranium has the highest affinity for AE, the crowding step can be very efficient.

[0123] The spent RC solution (2) exiting area X is discharged through a secondary CIX system.

[0124] The uranium-loaded secondary regeneration solution (6) from Area X-2 is transferred to the secondary-loaded regeneration settling system.

[0125] As the AE media moves from zone X-2 to zone X-4, it is being regenerated using a strong acid, such as sulfuric acid. The regenerated AE media (5) is then transferred to a post-regeneration water wash step and finally returned to the secondary CIX system, where it is again contacted with fresh primary charge regeneration solution taken from the primary CIX system.

[0126] In an embodiment, the dual-cycle CIX apparatus (and process) includes a GE or RC system within a primary or secondary CIX system. In an embodiment, the dual-cycle CIX apparatus (and process) includes a GE system and an RC system, one within the primary CIX system and one within the secondary CIX system.

[0127] Examples of contaminants that can be removed by GE and RC processes include iron and phosphorus ions. While there may be trace amounts of other anion complexes that can be removed in AE systems, iron and phosphorus are the primary items to consider. For CE primary CIX systems, the operating concept is similar, except that in the case of CE, a portion of the loaded primary regeneration solution (ammonium uranyl carbonate) is treated with a small amount of acid, e.g., H2SO4, and then used to crowd the CE resin before the regeneration step. Again, under these conditions, uranium in a reduced pH solution is loaded back onto the resin, displacing contaminant ions that have a lower affinity for the resin compared to uranium.

[0128] The uranium obtained from the process described above will typically be recovered as a uranium oxide (U3O8) product. This material will be prepared as discussed above in a hydrogen peroxide precipitation system, with subsequent calcination of the precipitated uranyl peroxide to produce U3O8. Uranium may also be recovered as a diuranic acid compound.

[0129] The terms "area" or "port" or "system" can be used interchangeably to refer to a specific system used to perform a portion of an overall process. The terms "subarea" or "subport" or "subsystem" refer to a portion of a system that performs a subport of a specific portion of an overall process. With respect to GE and RC systems, the terms "system" and "subsystem" are used interchangeably.

[0130] In embodiments, the systems (units) described herein, such as the single-cycle CIX system, the primary and secondary CIX systems of a dual-cycle CIX system, the GE system, and the RC system, can each contain several zones, for example, 1 to 50 zones. The systems can each include 1, 2, 3, 4, or 5 zones. The systems can include 1 to 10 zones, 1 to 50 zones, 5 to 45 zones, 10 to 40 zones, 15 to 35 zones, 20 to 35 zones, 25 to 30 zones, or 24 to 32 zones. Zones are fixed feed and discharge points for the systems that do not move.

[0131] In embodiments, each of the systems described herein can have several resin chambers, e.g., 1 to 50 resin chambers. Each system can include 1, 2, 3, 4, or 5 zones. The systems can include 1 to 10 zones, 1 to 50 zones, 5 to 45 zones, 10 to 40 zones, 15 to 35 zones, 20 to 35 zones, 25 to 30 zones, or 24 to 32 zones. In embodiments, the resin remains within the chamber, and the resin chambers move from zone to zone, providing a continuous process without any interruptions. Each resin chamber remains within each CIX system or unit. For example, the resin chamber of the primary system does not move to the secondary system of a dual-cycle system.

[0132] As will be understood by one of ordinary skill in the art, each embodiment disclosed herein can comprise, consist essentially of, or consist of its particular described elements, steps, ingredients, or components. Accordingly, the terms "include" or "including" should be interpreted as reciting "comprises, consists of, or consists essentially of." The transitional terms "comprises" or "comprises" mean "including, but not limited to," and allow for the inclusion of unspecified elements, steps, ingredients, or components, even in major amounts. The transitional phrase "consisting of" excludes any unspecified element, step, ingredient, or component. The transitional phrase "consisting essentially of" limits the scope of the embodiment to the specified elements, steps, ingredients, or components and those that do not materially affect the embodiment.

[0133] All numerical values ​​expressing quantities of ingredients, properties of reagents, reaction conditions, and the like used in the specification and claims, unless indicated to the contrary, are to be understood as being modified in all instances by the term "about." Accordingly, the numerical parameters set forth in the specification and appended claims are approximations that may vary depending on the desired properties sought to be obtained. At the very least, each numerical parameter should be construed in light of at least the number of reported significant digits and by applying ordinary rounding techniques. Where further clarification is needed, the term "about," when used in conjunction with a stated numerical value or range, has the meaning reasonably ascribed to it by one of ordinary skill in the art, i.e., slightly more or slightly less than the stated value or range, ±20% of the stated value, ±15% of the stated value, ±10% of the stated value, ±5% of the stated value, ±4% of the stated value, ±3% of the stated value, ±2% of the stated value, ±1% of the stated value, or within any percentage range between ±1% and ±20% of the stated value.

[0134] Notwithstanding that the numerical ranges or parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0135] As used in the context of describing the present invention (particularly in the context of the claims below), the terms "a," "an," "the," and similar referents are intended to encompass both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of individually referring to each separate value falling within the range. Unless otherwise indicated herein, each separate value is incorporated herein to the same extent as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted otherwise by context. The use of any examples or exemplary language (e.g., "etc.") provided herein is intended merely to better elucidate the invention and does not pose a limitation on the scope of the invention as otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0136] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group element may be referenced and claimed individually or in any combination with other elements of the group or other elements found herein. It is anticipated that one or more elements of a group may be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion is made, the specification is deemed to contain the group as modified, and accordingly implements the written description of all Markush groups used in the appended claims.

[0137] The following exemplary embodiments and examples illustrate the exemplary methods provided herein. These exemplary embodiments and examples are not intended to limit the scope of the disclosure, and they should not be construed as such. It will be apparent that the method can be practiced in ways other than those specifically described herein. Numerous modifications and variations are possible in light of the teachings herein and, therefore, are within the scope of the disclosure. Exemplary Embodiments

[0138] The following are exemplary embodiments. 1. A single cycle continuous ion exchange (CIX) apparatus for recovering uranium, comprising: a) a primary CIX system, including a gradient elution (GE) or resin crowding (RC) system; b) a primary regenerated solution evaporation system; c) a uranyl precipitate filtration / washing / digestion system; d) an acidified uranyl salt solution precipitation system; e) a precipitated uranium cleaning / calcination system; Including, Optionally, the primary CIX system comprises a GE or RC system; Optionally, the single cycle CIX device includes a uranium product storage and automated packaging system. Single-cycle continuous ion exchange (CIX) unit. 2. A single-cycle CIX apparatus as described in embodiment 1, wherein the primary regenerated solution evaporation system includes a recovery condenser for recovering decomposed compounds, e.g., ammonia. 3. A dual-cycle CIX plant for recovering uranium, comprising: a) a primary CIX system, including a GE or RC system; b) a secondary CIX system, including a GE or RC system; c) a secondary regenerated solution precipitation system; d) a uranyl precipitate filtration / washing / digestion system; e) a precipitated uranium cleaning / calcination system; Including, Optionally, the primary and / or secondary CIX systems include GE or RC systems; Optionally, the single cycle CIX device includes a uranium product storage and automated packaging system. Dual cycle CIX device. 4. The single-cycle or dual-cycle CIX apparatus of any one of embodiments 1-3, further comprising a pretreatment system prior to the primary CIX system, the pretreatment system comprising a clay addition system / step, a flocculant addition system / step, and / or a purification system / step. 5. A single-cycle or dual-cycle CIX device according to any one of embodiments 1-4, wherein the primary CIX system comprises a complexed cation exchange (CE) medium. 6. The dual cycle CIX apparatus of any one of embodiments 3-5, wherein the secondary CIX system comprises an anion exchange (AE) medium. 7. A single-cycle or dual-cycle CIX device according to any one of embodiments 1-6, wherein the system allows for recycling, returning, or storing the solution. 8. A single or dual cycle CIX device according to any one of embodiments 1-7, wherein the system allows for routine cleaning of the solid media of the primary CIX and / or secondary CIX. 9. A single or dual cycle CIX apparatus as described in embodiment 8, wherein the primary and secondary CIX systems have at least one zone within the system operated in an upflow mode to allow expansion of the solid media for cleaning at least once per full cycle of the CIX system. 10. A single or dual cycle CIX apparatus according to any one of embodiments 1-9, wherein the system is connected in series for the recovery of uranium from a source. 11. A method for recovering uranium, comprising: a) providing a source of uranium; b) providing one or more CIX systems including a solid medium for binding uranium; c) applying a source of uranium to the solid medium under conditions that bind the uranium to the solid medium; d) recovering uranium by a single-cycle or dual-cycle CIX process; Including, Single-cycle CIX processes include GE or RC processes, Dual cycle ion exchange processes include GE and / or RC processes, method. 12. The method of embodiment 11, wherein the CIX system is a primary CIX system of a single-cycle CIX device. 13. The method of embodiment 11, wherein two CIX systems are present, the two CIX systems being the primary and secondary CIX systems of a dual-cycle CIX device. 14. The method of any one of embodiments 11-13, wherein the primary CIX system comprises a complexing cation exchange (CE) resin that binds uranium. 15. The method of embodiment 11 or 13, wherein the secondary CIX system comprises an anion exchange (AE) resin that binds uranium. 16. The method of any one of embodiments 11-15, wherein the method further comprises pretreating the source of uranium before step c). 17. The method of embodiment 16, wherein the pretreating step includes filtering or purifying the source of uranium using activated clay, activated carbon, activated silica, a flocculant, or a combination thereof. 18. The method of any one of embodiments 11-17, wherein the source of uranium is a source of phosphoric acid containing uranium in any oxidation state. 19. The method of any one of embodiments 11-18, wherein the source of uranium comprises a phosphoric acid solution or a phosphoric acid raw material. 20.CE medium is Weakly acidic CE media with chelating aminomethylphosphonic acid groups, Aminophosphonic chelating media, a macroporous polystyrene-based chelating medium with iminodiacetic acid groups, or a composition or material comprising an agent having a chelating group, functionality, or moiety that binds uranium, or comprising an iminodiacetic acid group, a chelating aminomethylphosphonic acid group, or an aminophosphonic group, optionally wherein the composition or material comprises a bead, wire, mesh, nanobead, nanotube, or hydrogel; 20. The method of any one of embodiments 11-19, comprising: 21. The method of any one of embodiments 11-20, wherein recovering uranium by a single-cycle ion exchange process or by a dual-cycle ion exchange process includes pretreating the CE media with an alkaline solution to neutralize free acid in the CE media, and subsequently regenerating the CE media with an alkaline carbonate solution at a pH greater than about 9.0 to produce a uranium-loaded primary regeneration solution and a regenerated CE media. 22. The method of embodiment 21, wherein the alkaline solution for pretreating the CE medium comprises ammonium hydroxide or sodium hydroxide. 23. The method of embodiment 21 or 22, wherein when pretreating the CE media, at least one zone is run in an upflow operating mode to allow purging of trace amounts of solids from the CIX system. 24. The method of any one of embodiments 21-23, wherein the step of regenerating the CE media using an alkaline carbonate solution includes converting uranium to an anionic uranyl carbonate complex to produce a uranium-loaded primary regeneration solution comprising the anionic uranyl carbonate complex, and the alkaline carbonate solution comprises ammonium carbonate, sodium carbonate, or potassium carbonate. 25. The method of any one of embodiments 21-24, wherein the step of regenerating the CE media further comprises washing the regenerated CE media with water or a weak acid solution before re-entering the CE media into the CIX process. 26. The method of any one of embodiments 21-25, wherein the single-cycle ion exchange process further comprises pretreating the CE media with an alkaline solution, the alkaline solution comprising a portion of the initial regeneration solution, thereby reloading the uranium contained in the initial regeneration solution onto the CE media. 27. The method of any one of embodiments 21-27, wherein the single-cycle ion exchange process further comprises concentrating the uranium-loaded primary regenerated solution in an evaporation unit to reduce the water content, decomposing excess alkali carbonate, forming bicarbonate, reducing the pH of the solution, and forming a uranyl precipitate, wherein the alkali carbonate is ammonium carbonate, sodium carbonate, or potassium carbonate, and optionally the alkali carbonate is ammonium carbonate and the uranyl precipitate is ammonium uranyl tricarbonate. 28. The method of embodiment 27, wherein the method further comprises filtering the uranyl precipitate and subsequently washing the precipitate with water to remove excess alkali carbonate or entrained carbonate / bicarbonate from the uranyl precipitate. 29. The method of embodiment 27 or 28, wherein the method further comprises recovering compounds released in the decomposition of the excess alkali carbonate and recycling the recovered compounds and the resulting solution to the CIX device, optionally wherein the released compound is ammonia. 30. The method of any one of embodiments 27-29, wherein the method further comprises digesting the uranyl precipitate with an acid solution to produce a uranyl salt solution, optionally wherein the acid solution comprises sulfuric acid, nitric acid, or hydrochloric acid. 31. The method of embodiment 30, wherein the method further comprises treating the uranyl salt solution with an alkaline solution to increase the pH of the solution to between about pH 2.5 and about pH 7 or between about pH 3.5 and about pH 6 to obtain a pH-adjusted solution, optionally wherein the alkaline solution comprises an alkali hydroxide, and optionally wherein the alkaline solution has a pH greater than about pH 10. 32. The method of embodiment 31, wherein the method further comprises adding an agent to the pH-adjusted solution in an amount sufficient to form a precipitate, the agent being hydrogen peroxide, ammonium hydroxide, ammonium carbonate, sodium hydroxide, sodium carbonate, or potassium hydroxide, and optionally, the agent being hydrogen peroxide and the precipitate being a uranyl peroxide precipitate. 33. The method of embodiment 32, wherein the method further comprises separating the precipitate from the pH-adjusted solution by (i) settling, filtering, or centrifuging the precipitate, followed by washing the precipitate with water, or (ii) washing the precipitate on a filter or repulping the precipitate with water, followed by settling, filtering, or centrifuging the precipitate; optionally, the method further comprises an additional step of washing the precipitate with water. 34. The method of embodiment 32, wherein the method further comprises drying the precipitate to form a dry solid. 35. The method of embodiment 34, wherein the method further comprises heating the dry solid to a temperature sufficient to decompose or calcinate the dry solid, and optionally, the dry solid is uranyl peroxide and calcining the dry solid forms uranium oxide. 36. The method of any one of embodiments 21-25, wherein the dual cycle ion exchange process further comprises treating the uranium-loaded primary regenerant solution in a second CIX system containing an anion exchange (AE) medium, and the anionic uranyl carbonate complexes are transferred to the AE medium. 37. The method of embodiment 36, wherein the AE medium comprises a functional group, including a type 1 quaternary ammonium. 38. The method of embodiment 36 or 37, wherein the method further comprises treating the AE medium with an aqueous solution to produce a washed AE medium. 39. The method of embodiment 38, wherein the method further comprises treating the washed AE media with an acidic solution to remove uranium from the AE media and produce a uranium-loaded secondary regenerated solution containing uranium in cationic form and regenerated AE media, optionally wherein the acidic solution comprises dilute sulfuric acid, nitric acid, or hydrochloric acid. 40. The method of embodiment 39, wherein the step of treating the washed AE media with an acidic solution is carried out in an upflow operating mode for at least one of the contacting steps (in at least one of the compartments) to purge any trace amounts of solids that may have accumulated in the CIX system. 41. The method of embodiment 39 or 40, wherein the method further comprises treating the regenerated AE medium with water. 42. The method of any one of embodiments 36-42, wherein the method further comprises post-treating the regenerated AE media with an alkaline solution prior to its re-entry into the second CIX system. 43. The method of any one of embodiments 36-42, wherein the method further comprises treating the uranium-loaded secondary regenerated solution with an alkaline solution to increase the pH of the solution to about pH 2.5 to about pH 7 or about pH 3.5 to about pH 6 to obtain a pH-adjusted solution, optionally wherein the alkaline solution comprises an alkali hydroxide, ammonium hydroxide, or sodium hydroxide at a concentration ranging from 10% to about 30%, and optionally wherein the alkaline solution has a pH greater than pH 10. 44. The method of embodiment 43, wherein the method further comprises adding a chemical to the pH-adjusted solution in an amount sufficient to form a precipitate, the chemical being hydrogen peroxide, ammonium hydroxide, ammonium carbonate, sodium hydroxide, sodium carbonate, or potassium hydroxide, and optionally, the chemical being hydrogen peroxide and the precipitate being a uranyl peroxide precipitate. 45. The method of embodiment 44, wherein the method further comprises separating the precipitate from the pH-adjusted solution by (i) settling, filtering, or centrifuging the precipitate, followed by washing the precipitate with water, or (ii) washing the precipitate on a filter or repulping the precipitate with water, followed by settling, filtering, or centrifuging the precipitate; optionally, the method further comprises an additional step of washing the precipitate with water. 46. ​​The method of embodiment 45, wherein the method further comprises drying the precipitate to form a dry solid. 47. The method of embodiment 46, wherein the method further comprises heating the dry solid to a temperature sufficient to decompose or calcinate the dry solid, and optionally, the dry solid is uranyl peroxide and calcining the dry solid forms uranium oxide. 48. The method of any one of embodiments 11-47, wherein the primary CIX system includes a GE or RC system. 49. The method of any one of embodiments 11, 13-26, and 36-47, wherein the secondary CIX system includes a GE or RC system. 50. The method of any one of embodiments 11, 13-26, 36-47, and 49, wherein the primary and secondary CIX systems include GE and / or RC systems. 51. The method of any one of embodiments 11-50, wherein the GE process carried out in the primary CIX system of a single-cycle or dual-cycle CIX process includes applying a dilute base solution to the primary CE media during a regeneration pretreatment step, which is performed after the primary CE media has been loaded with uranium and before regeneration of the primary CE media. 52. The method of embodiment 51, wherein the GE process includes applying a dilute base solution of increased strength to remove non-uranium cations from the primary CE medium. 53. The method of embodiment 51 or 52, wherein the dilute base solution comprises a dilute carbonate solution, such as a dilute ammonium carbonate solution, a dilute sodium carbonate solution, or a dilute potassium carbonate solution; optionally, the selected dilute base solution comprises an ammonium carbonate solution. 54. The method of any one of embodiments 11-50, wherein the RC process carried out in the primary CIX system of a single-cycle or dual-cycle CIX process includes adjusting the pH of a portion of the uranium-loaded primary regenerant solution using dilute acid to obtain a cloud solution. 55. The method of embodiment 54, wherein a portion of the uranium-loaded primary regenerant solution is obtained from an initial application of the primary regenerant solution to the primary CE medium or from a low-purity recycled / stored uranium-loaded regenerant solution. 56. The method of embodiment 54 or 55, wherein adjusting the pH of a portion of the uranium-loaded primary regeneration solution converts the uranium in the solution to a cationic form and obtains a cloud solution. 57. The method of embodiment 56, wherein the RC process further comprises applying the cloud solution onto the primary CE media during a regeneration pretreatment step, which is performed after the primary CE media has been loaded with uranium and before regeneration of the primary CE media. 58. The method of embodiment 57, wherein applying the cloud solution onto the primary CE medium reloads uranium onto the primary CE medium and displaces non-uranium contaminants from the primary CE medium. 59. The method of any one of embodiments 11, 13-26, and 36-57, wherein the GE process carried out in the secondary CIX system of the dual-cycle CIX process includes applying a weak acidic solution to the secondary AE media during a regeneration pretreatment step, which is performed after the secondary AE media has been loaded with uranium and before regeneration of the secondary AE media. 60. The method of embodiment 59, wherein the GE process includes applying a weak acidic solution of increased strength to remove non-uranium anions from the secondary AE medium. 61. The method of embodiment 59 or 60, wherein the weak acid solution comprises a weak sulfuric acid solution, a weak hydrochloric acid solution, or a weak nitric acid solution. 62. The method of any one of embodiments 11, 13-26, and 36-58, wherein the RC process carried out in the secondary CIX system of the dual-cycle CIX process includes adjusting the pH of a portion of the uranium-loaded secondary regenerated solution using a weak base to obtain a cloud solution. 63. The method of embodiment 62, wherein a portion of the uranium-loaded secondary regenerated solution is obtained from an initial application of the secondary regenerated solution to the secondary AE medium or from a low-purity recycled / stored uranium-loaded regenerated solution. 64. The method of embodiment 62 or 63, wherein adjusting the pH of a portion of the uranium-loaded secondary regeneration solution converts the uranium in the solution to an anionic form and obtains a cloud solution. 65. The method of embodiment 64, wherein the RC process further comprises applying the cloud solution onto the secondary AE media during a pre-regeneration treatment step, which is performed after the secondary AE media has been loaded with uranium and before regeneration of the secondary AE media. 66. The method of embodiment 65, wherein applying the cloud solution onto the secondary AE medium reloads uranium onto the secondary AE medium and displaces non-uranium contaminants from the secondary AE medium. 67. A single-cycle CIX system or a dual-cycle CIX system according to any one of embodiments 1-10, wherein the GE or RC system comprises one or more zones. 68. A single-cycle CIX system or a dual-cycle CIX system according to embodiment 67, wherein the GE system comprises different zones for applying acids or bases of different strengths to the solid medium. 69. A single-cycle CIX system or a dual-cycle CIX system according to embodiment 67, wherein the RC system comprises a different zone for applying a pH-adjusted secondary regeneration solution. 70. A single-cycle CIX system or a dual-cycle CIX system according to any one of embodiments 67-69, wherein the GE or RC system includes an area for regenerating the AE or CE medium.

[0139] Certain embodiments of the present invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those skilled in the art upon perusal of the foregoing description. The inventors anticipate that skilled artisans will adopt such variations as appropriate, and the inventors intend the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Also, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0140] The subject matter described above is provided by way of example only and should not be construed as limiting. Various modifications and changes can be made to the subject matter described herein without following the exemplary embodiments and applications shown and described and without departing from the true spirit and scope of the invention as set forth in the following claims.

[0141] All publications, patents, and patent applications cited herein are incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. While the foregoing has been described in terms of various embodiments, those skilled in the art will understand that various modifications, substitutions, omissions, and alterations may be made without departing from the spirit thereof. (Item 1) 1. A single cycle continuous ion exchange (CIX) apparatus for recovering uranium, comprising: a) a primary CIX system, including a gradient elution (GE) or resin crowding (RC) system; b) a primary regenerated solution evaporation system; c) a uranyl precipitate filtration / washing / digestion system; d) an acidified uranyl salt solution precipitation system; e) Precipitated uranium cleaning / calcination system and A single cycle continuous ion exchange (CIX) apparatus comprising: (Item 2) Item 1. The single-cycle CIX device according to item 1, wherein the system further comprises a pretreatment system before the primary CIX system. (Item 3) 1. A dual cycle CIX apparatus for recovering uranium, comprising: a) a primary CIX system, including a GE or RC system; b) a secondary CIX system, including a GE or RC system; c) a secondary regenerated solution precipitation system; d) a uranyl precipitate filtration / washing / digestion system; e) Precipitated uranium cleaning / calcination system and Including, Optionally, a dual cycle CIX apparatus, wherein only one of the primary or secondary CIX systems comprises a GE or RC system, and the other does not comprise a GE or RC system. (Item 4) Item 4. The dual-cycle CIX apparatus of item 3, wherein the system further comprises a pretreatment system before the primary CIX system. (Item 5) The primary CIX system is a single-cycle CIX device according to item 1 or 2 or a dual-cycle CIX device according to item 3 or 4, comprising a chelating or complexing cation exchange (CE) medium. (Item 6) 5. The dual-cycle CIX apparatus according to claim 3 or 4, wherein the secondary CIX system comprises an anion exchange (AE) medium. (Item 7) 10. The single-cycle CIX device of any one of items 1, 2, or 5 or the dual-cycle CIX device of any one of items 3-6, wherein the system allows for recycling, returning, or storing the solution. (Item 8) 8. A single or dual cycle CIX device according to any one of items 1-7, wherein the system allows for routine cleaning of the solid media of the primary CIX and / or the secondary CIX. (Item 9) 9. The single or dual cycle CIX apparatus according to claim 8, wherein the primary and secondary CIX systems are operated in an upflow mode to allow expansion of the solid media for purification. (Item 10) 10. A single or dual cycle CIX apparatus according to any one of items 1-9, wherein the systems are connected in series for the recovery of uranium. (Item 11) 1. A method for recovering uranium, comprising: a) providing a source of uranium; b) providing one or more CIX systems containing a solid medium for binding uranium; c) applying said source of uranium to said solid medium under conditions that bind said uranium to said solid medium; d) recovering said uranium by a single-cycle or dual-cycle CIX process; Including, The single cycle CIX process comprises a GE or RC process; The method, wherein the dual cycle ion exchange process comprises a GE and / or an RC process. (Item 12) Item 12. The method of item 11, wherein the CIX system is the primary CIX system of a single-cycle CIX device. (Item 13) Item 12. The method of item 11, wherein two CIX systems are present, the two CIX systems being the primary and secondary CIX systems of a dual-cycle CIX device. (Item 14) 14. The method of any one of items 11-13, wherein the primary CIX system comprises a chelating or complexing cation exchange (CE) resin that binds uranium. (Item 15) 14. The method of claim 11 or 13, wherein the secondary CIX system comprises an anion exchange (AE) resin that binds uranium. (Item 16) 16. The method of any one of items 11-15, further comprising pretreating the source of uranium prior to step c). (Item 17) 17. The method of claim 16, wherein the pre-treating step comprises filtering or purifying the source of uranium using activated clay, activated carbon, activated silica, a flocculant, or a combination thereof. (Item 18) 18. The method of any one of items 11-17, wherein the source of uranium is a source of phosphoric acid comprising uranium in any oxidation state. (Item 19) 19. The method of any one of items 11-18, wherein the source of uranium comprises a phosphoric acid solution or a phosphoric acid raw material. (Item 20) The above CE media is Weakly acidic CE media with chelating aminomethylphosphonic acid groups, Aminophosphonic chelating media, a macroporous polystyrene-based chelating medium with iminodiacetic acid groups, or A composition or material comprising an agent having a chelating group, functionality, or moiety that binds uranium, or comprising an iminodiacetic acid group, a chelating aminomethylphosphonic acid group, or an aminophosphonic group, optionally comprising a bead, wire, mesh, nanobead, nanotube, or hydrogel. 20. The method according to any one of items 11-19, comprising: (Item 21) 21. The method of any one of items 11-20, wherein recovering the uranium by a single-cycle CIX process or by a dual-cycle CIX process includes pretreating the CE media with an alkaline solution to neutralize free acid in the CE media, and subsequently regenerating the CE media with an alkaline carbonate solution at a pH greater than about 9.0 to produce a uranium-loaded primary regeneration solution and a regenerated CE media. (Item 22) 22. The method of claim 21, wherein the alkaline solution for pretreating the CE medium comprises ammonium hydroxide or sodium hydroxide. (Item 23) 23. The method according to item 21 or 22, wherein the step of pretreating the CE medium is carried out in an upflow operation mode. (Item 24) 24. The method of any one of items 21-23, wherein regenerating the CE media with an alkaline carbonate solution comprises converting the uranium to an anionic uranyl carbonate complex to produce the uranium-loaded primary regeneration solution comprising the anionic uranyl carbonate complex, wherein the alkaline carbonate solution comprises ammonium carbonate, sodium carbonate, or potassium carbonate. (Item 25) 25. The method of any one of items 21-24, wherein the step of regenerating the CE media further comprises washing the regenerated CE media with water or a weak acid solution before re-entering the CE media into the CIX process. (Item 26) 26. The method of any one of items 21-25, wherein the single cycle ion exchange process further comprises pretreating the CE media with an alkaline solution comprising a portion of the initial regeneration solution, thereby reloading the uranium contained in the initial regeneration solution onto the CE media. (Item 27) 28. The method of any one of claims 21-27, wherein the single cycle ion exchange process further comprises concentrating the uranium-loaded primary regenerated solution in an evaporation unit to reduce the water content and decompose excess alkali carbonate, followed by reducing the pH of the solution and forming a uranyl precipitate. (Item 28) 28. The method of claim 27, further comprising filtering the uranyl precipitate and subsequently washing the precipitate with water to remove excess alkali carbonate or contaminating carbonate / bicarbonate from the uranyl precipitate. (Item 29) 29. The method according to item 27 or 28, further comprising recovering compounds released in the decomposition of the excess alkali carbonate and recycling the recovered compounds and the resulting solution. (Item 30) 30. The method of any one of items 27-29, further comprising digesting the uranyl precipitate with an acid solution to produce a uranyl salt solution, optionally wherein the acid solution comprises sulfuric acid, nitric acid, or hydrochloric acid. (Item 31) Item 31. The method of claim 30, further comprising treating the uranyl salt solution with an alkaline solution to increase the pH of the solution to about pH 2.5 to about pH 7 or about pH 3.5 to about pH 6 to obtain a pH-adjusted solution, optionally comprising an alkali hydroxide, and optionally having a pH greater than about pH 10. (Item 32) 32. The method of claim 31, further comprising adding hydrogen peroxide to the pH-adjusted solution in an amount sufficient to form a uranyl peroxide precipitate. (Item 33) 33. The method of claim 32, further comprising separating the uranyl peroxide precipitate from the pH-adjusted solution by (i) settling, filtering, or centrifuging the precipitate, followed by washing the precipitate with water, or (ii) washing the precipitate on a filter or repulping the precipitate with water, followed by settling, filtering, or centrifuging the precipitate, optionally further comprising an additional step of washing the uranyl peroxide precipitate with water. (Item 34) 33. The method of claim 32, further comprising drying the uranyl peroxide precipitate to form a dry solid. (Item 35) 35. The method of claim 34, further comprising heating the dry solid to a temperature sufficient to decompose or calcinate the dry solid and form uranium oxide. (Item 36) 26. The method of any one of claims 21-25, wherein the dual cycle ion exchange process further comprises treating the uranium-loaded primary regenerated solution in a second CIX system containing an anion exchange (AE) medium, and the anionic uranyl carbonate complexes are transferred to the AE medium. (Item 37) Item 37. The method according to item 36, wherein the AE medium has a functional group containing type 1 quaternary ammonium. (Item 38) Item 38. The method according to item 36 or 37, further comprising treating the AE medium with an aqueous solution to produce a washed AE medium. (Item 39) Item 39. The method of item 38, further comprising treating the washed AE media with an acidic solution to remove uranium from the AE media and produce a uranium-loaded secondary regeneration solution containing the uranium in cationic form and regenerated AE media, optionally wherein the acidic solution comprises dilute sulfuric acid, nitric acid, or hydrochloric acid. (Item 40) Item 40. The method according to item 39, wherein the step of treating the washed AE media with the acidic solution is carried out in an upflow operation mode. (Item 41) 41. The method according to item 39 or 40, further comprising treating the regenerated AE medium with water. (Item 42) Item 42. The method of claim 41, further comprising post-treating the regenerated AE medium with an alkaline solution prior to its re-entry into the second CIX system. (Item 43) 43. The method of any one of items 36-42, wherein the method further comprises treating the uranium-loaded secondary regenerated solution with an alkaline solution to increase the pH of the solution to about pH 2.5 to about pH 7 or about pH 3.5 to about pH 6 to obtain a pH-adjusted solution, optionally the alkaline solution comprising alkali hydroxide, ammonium hydroxide, or sodium hydroxide at a concentration ranging from 10% to about 30%, and optionally the alkaline solution has a pH greater than pH 10. (Item 44) 44. The method of claim 43, further comprising adding hydrogen peroxide to the pH-adjusted solution in an amount sufficient to form a uranyl peroxide precipitate. (Item 45) Item 45. The method of claim 44, further comprising separating a uranyl peroxide precipitate from the pH-adjusted solution by (i) settling, filtering, or centrifuging the precipitate, followed by washing the precipitate with water, or (ii) washing the precipitate on a filter or repulping the precipitate with water, followed by settling, filtering, or centrifuging the precipitate, optionally further comprising an additional step of washing the uranyl peroxide precipitate with water. (Item 46) Item 46. The method of claim 45, further comprising drying the uranyl peroxide precipitate to form a dry solid. (Item 47) Item 47. The method of claim 46, further comprising heating the dry solid to a temperature sufficient to decompose or calcinate the dry solid and form uranium oxide. (Item 48) 48. The method of any one of items 11-47, wherein the primary CIX system comprises a GE or RC system. (Item 49) Item 11. The method of any one of items 11, 13-26, and 36-47, wherein the secondary CIX system comprises a GE or RC system. (Item 50) 50. The method of any one of items 11, 13-26, 36-47, and 49, wherein the primary and secondary CIX systems comprise GE and / or RC systems. (Item 51) 51. The method of any one of items 11-50, wherein the GE process carried out in the primary CIX system of the single-cycle or dual-cycle CIX process includes applying a dilute base solution to the primary CE medium during the regeneration pretreatment step. (Item 52) 52. The method of claim 51, wherein the GE process includes applying the dilute base solution of increased strength to remove non-uranium cations from the primary CE media. (Item 53) 53. The method of claim 51 or 52, wherein the dilute base solution comprises an ammonium carbonate solution, a dilute sodium carbonate solution, or a dilute potassium carbonate solution. (Item 54) 51. The method of any one of items 11-50, wherein the RC process implemented in the primary CIX system of the single-cycle or dual-cycle CIX process includes adjusting the pH of a portion of the uranium-loaded primary regenerant solution with dilute acid to obtain a cloud solution. (Item 55) 55. The method of claim 54, wherein a portion of the uranium-loaded primary regenerant solution is obtained from an initial application of the primary regenerant solution to the primary CE medium or from a lower purity recycled / stored uranium-loaded regenerant solution. (Item 56) 57. The method of claim 54 or 55, wherein adjusting the pH of a portion of the uranium-loaded primary regeneration solution converts the uranium in the solution to a cationic form to obtain a cloud solution. Item 57. The method of item 56, wherein the RC process further comprises applying the cloud solution onto the primary CE medium during the regeneration pretreatment step. (Item 58) 58. The method of claim 57, wherein applying the cloud solution onto the primary CE medium reloads the uranium onto the primary CE medium and displaces non-uranium contaminants from the primary CE medium. (Item 59) The method according to any one of items 11, 13-26, and 36-57, wherein the GE process carried out in the secondary CIX system of the dual-cycle CIX process includes applying a weak acid solution to the secondary AE medium during the regeneration pretreatment step. (Item 60) 60. The method of claim 59, wherein the GE process includes applying the weak acid solution of increased strength to remove non-uranium anions from the secondary AE medium. (Item 61) 61. The method of claim 59 or 60, wherein the weak acid solution comprises a weak sulfuric acid solution, a weak hydrochloric acid solution, or a weak nitric acid solution. (Item 62) 19. The method of any one of items 11, 13-26, and 36-58, wherein the RC process carried out in the secondary CIX system of the dual-cycle CIX process includes adjusting the pH of a portion of the uranium-loaded secondary regenerated solution with a weak base to obtain a cloud solution. (Item 63) Item 63. The method of item 62, wherein a portion of the uranium-loaded secondary regenerated solution is obtained from an initial application of the secondary regenerated solution to the secondary AE medium or from a lower purity recycled / stored uranium-loaded regenerated solution. (Item 64) Item 65. The method of claim 62 or 63, wherein adjusting the pH of a portion of the uranium-loaded secondary regeneration solution converts the uranium in the solution to an anionic form to obtain a cloud solution. Item 65. The method according to item 64, wherein the RC process further comprises applying the cloud solution onto the secondary AE medium during the pre-regeneration treatment step, which is performed after the secondary AE medium has been loaded with uranium and before regeneration of the secondary AE medium. (Item 66) Item 66. The method of claim 65, wherein applying the cloud solution onto the secondary AE medium reloads the uranium onto the secondary AE medium and displaces non-uranium contaminants from the secondary AE medium. (Item 67) 11. The single-cycle or dual-cycle CIX system of any one of items 1-10, wherein the GE or RC system comprises one or more zones. (Item 68) 68. The single-cycle or dual-cycle CIX system according to item 67, wherein the GE system comprises different zones for applying acids or bases of different strengths to the solid medium. (Item 69) Item 70. The single-cycle CIX system or dual-cycle CIX system according to Item 67, wherein the RC system comprises a separate zone for applying a pH-adjusted secondary regenerant solution. 70. The single-cycle or dual-cycle CIX system of any one of items 67-69, wherein the GE or RC system comprises an area for regenerating the AE or CE medium.

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