Uranium Recovery from Uranyl Nitrate Solution

Abstract

A method for recovering useful metals from a nitrate solution of a metal cation or a metal oxide cation is carried out by dropping the nitrate solution from the inlet of a production column. The production column contains a circulating solution containing a base selected from any one of ammonia, ammonium hydroxide, an alkali metal hydroxide, and an alkaline earth metal hydroxide. The nitrate reacts with the base in the circulating solution and precipitates as a metal oxide salt or a metal hydroxide salt. The precipitate and the circulating solution are discharged from the outlet nozzle of the production column, the precipitate is collected by a basket disposed below the production column, and the circulating solution is recovered in a recovery tank disposed below the basket. The recovered circulating solution is pumped back from the recovery tank to the production column. The nitrate of the metal cation may be, for example, the nitrate of a radioactive metal cation such as uranium or uranyl cation.

Description

Technical Field

[0001] Various embodiments disclosed herein relate to the recovery of radioactive metals, such as uranium, as ceramics from raw materials for forming uranate gel particles, such as uranyl nitrate particles.

Background Art

[0002] Metal nitrates are useful precursors for metal oxides prepared by the sol-gel method, and the metals include main group metals (such as lead), transition metals (such as yttrium, iron, zirconium), or lanthanide metals.

[0003] For example, iron oxide has been prepared by heating the product of a sol-gel reaction between iron(III) nitrate and ethylene glycol. Depending on the conditions, maghemite and / or hematite may be formed from iron(III) nitrate. Lead zirconate titanate (PZT) powder can be prepared by the sol-gel method using lead nitrate, zirconium nitrate, and tetrabutyl titanate as precursors. Yttrium oxide can be prepared by the sol-gel method using yttrium nitrate as a precursor.

[0004] Nitrate precursors can also be used to prepare oxides of radioactive metals. Uranyl nitrate is a water-soluble uranium compound and is useful for the production of uranium oxide nuclei in nuclear fuel applications. Oxides of plutonium and thorium are also utilized in the nuclear energy field and can be prepared by the sol-gel method from the corresponding nitrates. Radioactive metal oxide gel particles can be prepared using those containing hexamethylenetetramine (HMTA) and urea in a uranyl nitrate solution. +2 A metal ion-urea complex of UO2((NH2)2CO)2 is initially formed, and urea may help suppress early gelation. This solution is then heated to a sufficient temperature to cause HMTA decomposition. When the metal ion-urea complex is heated, UO2 +2Or may dissociate to form similar uranyl oxides. Metal ions hydrolyze and condense as in reactions (1) and (2).

[0005] (UO2) +2 (aq) +2H2O→(UO2(OH)2) (aq) +2H + (1) 2(UO2(OH)2) (aq) →2UO3·2H2O (2)

[0006] At the same time, HMTA decomposes to produce ammonium hydroxide. Ammonium hydroxide raises the pH of the solution, promotes hydrolysis and condensation, and results in the formation of metal ion particles 2UO3·2H2O as spherical gel particles. The uranium oxide gel spheres are collected and sintered to form ceramic particles useful as the core of nuclear fuel pellets.

[0007] Uranyl nitrate waste is regulated as hazardous radioactive waste. Therefore, uranyl nitrate in waste or waste materials is not easily disposed of. Radioactive uranium can be recovered from a uranyl nitrate solution by generating an insoluble uranate using a base. For example, when uranyl nitrate is reacted with ammonia or ammonium hydroxide, ammonium diuranate is produced.

[0008] When handling ammonium diuranate (ADU) precipitates, there are problems in handling the material because the solid is viscous. When raw ADU is transferred between containers, a large amount of the material remains, making cleaning work difficult and causing losses due to waste of the material.

[0009] In view of the current need for an improved method for recovering uranium from waste uranyl nitrate solution, an overview of various embodiments is briefly introduced. In this overview, some simplifications and omissions may be made, but this is for the purpose of highlighting and introducing some aspects of the subject matter disclosed herein and is not intended to limit the scope of the invention. In subsequent sections, a detailed description of specific embodiments will follow to enable those skilled in the art to make and use the inventive concept.

[0010] When a sol-gel reaction is carried out using metal nitrates to produce metal oxides, unreacted nitrates often remain in the supernatant after the oxide gel is produced. Such unreacted metal nitrates, especially when they contain heavy metals and / or radioactive metal nitrates, cannot be easily disposed of. These nitrates are environmental pollutants and may be toxic to humans and animals exposed to them. The present disclosure relates to a method for recovering and reusing metals from waste metal nitrate solutions.

[0011] Although various embodiments disclosed herein relate to the recovery of uranium from uranyl nitrate solutions, the disclosed processes are not limited specifically to uranium or generally to radioactive metals. The disclosed method can be generalized to the recovery of metals from solutions of metal cations or metal oxycations of nitrates.

[0012] One general aspect disclosed herein involves a method for recovering useful metals from a solution of a nitrate of a metal cation or metal oxycation. The method includes adding a solution of the nitrate to a production column having an inlet and an outlet nozzle, the solution of the nitrate being added dropwise through the inlet, and the production column containing a circulating solution containing a base selected from the group consisting of ammonia, ammonium hydroxide, alkali metal hydroxides, and alkaline earth metal hydroxides. The method also includes reacting the nitrate in the solution with the base in the circulating solution to produce a metal oxide salt or a metal hydroxide salt as a precipitate. The precipitate and the circulating solution are discharged from the production column through the outlet nozzle, the precipitate is collected in a basket disposed below the production column, the circulating solution is recovered in a recovery tank disposed below the basket, and the recovered circulating solution is pumped from the recovery tank to the production column.

[0013] Embodiments may include one or more of the following features. In various embodiments, the nitrate is a salt of one of the following cations or oxycations. It is a transition metal (e.g., iron, zirconium, or titanium), a lanthanide metal (e.g., cerium), or an actinide metal (e.g., uranium, thorium, or plutonium).

[0014] In various embodiments disclosed herein, the nitrate is uranyl nitrate, thorium nitrate, or plutonium nitrate. When the nitrate is uranyl nitrate, the base is ammonia or ammonium hydroxide, and the precipitate is ammonium diuranate.

[0015] In various embodiments, the precipitate is retained within the basket during the washing and drying steps. The method can include transferring the basket containing the collected precipitate from below the production column to an oxidation furnace and heating the basket containing the collected precipitate in the oxidation furnace to convert the precipitate to a metal oxide.

[0016] One general aspect includes a system for recovering useful metals from a nitrate solution of a metal cation or a metal oxycation. This system also includes the following: a production column having an inlet and an outlet nozzle, the production column configured such that the inlet drips the nitrate solution into the production column, a basket disposed under the outlet nozzle, a recovery tank disposed under the basket, and a circulation system. This circulation system can include a first pump and a flow path between the recovery tank and the production column. The first pump is configured to pump a circulating solution containing a base from the recovery tank to the production column. The recovery tank is configured to receive the circulating solution from the production column.

[0017] In various embodiments, the production column is configured such that the base in the circulating solution reacts with the nitrate solution to produce a metal oxide salt as a precipitate, and the outlet nozzle is configured such that the circulating solution and the precipitate exit the production column. The basket is configured to collect the precipitate while allowing the circulating solution to flow into the recovery tank.

[0018] Various embodiments relate to a method for recovering uranium from a uranyl nitrate solution, which is performed by adding the uranyl nitrate solution dropwise to a production column having an inlet and an outlet nozzle. This production column contains a circulating solution containing a base that is ammonia, ammonium hydroxide, an alkali metal hydroxide, or an alkaline earth metal hydroxide. The uranyl nitrate solution reacts with the base in the circulating solution to produce ammonium diuranate as a precipitate. This precipitate and the circulating solution are discharged through the outlet nozzle of the production column, the precipitate is collected in a basket under the production column, while the circulating solution is recovered in a recovery tank disposed under the basket. The recovered circulating solution is pumped from the recovery tank to the production column.

[0019] In various embodiments, the base is ammonia or ammonium hydroxide, and the precipitate is ammonium diuranate. The base may be ammonium hydroxide.

[0020] The base may be an alkali metal hydroxide, and the precipitate may be an alkali metal diuranate.

[0021] This method can further include the steps of washing the diuranate precipitate with an aqueous washing solution and drying the washed precipitate. The precipitate may be held in a basket during the washing and drying steps.

[0022] This method can include the step of moving a basket containing the collected precipitate from below the production column to an oxidation furnace. Next, the basket containing the collected precipitate can be heated in the oxidation furnace to convert the precipitate to uranium oxide. The uranium oxide may be UO2, U2O5, UO3, U3O8, UO2O2, or a mixture thereof.

[0023] Various embodiments disclosed herein relate to a system for recovering uranium from a uranyl nitrate solution. The system includes: a production column having an inlet and an outlet nozzle, the production column configured such that the inlet drips the uranyl nitrate solution into the production column; a basket disposed below the outlet nozzle; a recovery tank disposed below the basket; a first pump; and a flow path between the recovery tank and the production column, which is a circulation system.

[0024] The first pump is configured to pump a circulating solution containing a base from the recovery tank to the production column, and the recovery tank is configured to receive the circulating solution from the production column. The production column is configured such that the base in the circulating solution reacts with the uranyl nitrate solution to produce diuranate as a precipitate. The outlet nozzle is configured such that the circulating solution and the precipitate can exit the production column. The basket is configured to collect the precipitate and allow the circulating solution to flow into the recovery tank.

[0025] A system for recovering uranium from a uranyl nitrate solution can also include a washing station, a washing liquid discharge port, a washing tank below the washing liquid discharge port, a second pump, and means for moving a basket containing the collected precipitate from below the outlet nozzle of the production column to the washing station. In various embodiments, the second pump is configured to pump the washing liquid from the washing tank to the washing liquid discharge port to generate a flow of the washing liquid. The moving means is configured to place the basket below the washing liquid discharge port such that the collected precipitate is washed by the flow of the washing liquid.

[0026] A system for recovering uranium from a uranyl nitrate solution can also include an oxidation furnace and means for moving a basket containing the washed precipitate from the washing station to the oxidation furnace. The oxidation furnace is configured to convert the precipitate into uranium oxide.

[0027] As described above, the methods and apparatuses disclosed herein are not limited to common radioactive metals and particularly uranium. Various embodiments relate to a method for recovering a metal from a metal nitrate solution, which is performed by adding the metal nitrate solution dropwise to a production column having an inlet and an outlet nozzle. The production column contains a circulating solution containing a base that is ammonia, ammonium hydroxide, an alkali metal hydroxide, or an alkaline earth metal hydroxide. The metal nitrate solution reacts with the base in the circulating solution to produce a metal oxide salt or a metal hydroxide salt as a precipitate. The precipitate and the circulating solution are discharged through the outlet nozzle of the production column, and the precipitate is collected in a basket disposed below the production column while the circulating solution is recovered in a recovery tank disposed below the basket. The recovered circulating solution is pumped from the recovery tank to the production column. In various embodiments, the nitrate is a transition metal nitrate such as iron(III) nitrate or yttrium(III) nitrate. When iron(III) nitrate is used as a precursor, the base in the circulating solution is ammonium hydroxide and the precipitate is iron(III) hydroxide. Iron(III) hydroxide is converted into iron oxide in a furnace.

[0028] In various embodiments, the nitrate is a lanthanide metal nitrate such as cerium(III) nitrate. When cerium(III) nitrate is used as a precursor, the base in the circulating solution is ammonium hydroxide and the precipitate is cerium(III) hydroxide. Cerium(III) hydroxide is converted to yttrium oxide in a furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] To better understand various exemplary embodiments, reference is made to the accompanying drawings.

Figure 1

Figure 2

Figure 3

[0030] In the present disclosure, it will be understood that precipitates of metal oxide salts include precipitates of metal oxide salts, metal hydroxide salts, mixtures thereof, or metal oxide salts having hydroxide ligands.

[0031] The systems and methods disclosed herein are useful for recovering metal values from solutions of metal nitrates used as precursors in the synthesis of metal oxides. If unreacted metal nitrates remain from the synthesis of the desired oxide, it is not economically desirable to discard such nitrates. It is preferred to recover the metal values from the nitrate solution and convert the metal directly to the desired product or recycle the metal for reuse.

[0032] Furthermore, many oxides are made from toxic heavy metals or radioactive metals. When performing a sol-gel reaction to produce metal oxides using metal nitrates, it is common for unreacted nitrates to remain in the supernatant after the oxide gel is formed. Such unreacted metal nitrates, especially when nitrates of heavy metals and / or radioactive metals are involved, cannot be easily disposed of. These nitrates are environmental pollutants and can be harmful to humans and animals exposed to them. Even if the metal itself or the metal nitrate itself is not considered harmful, it may undergo chemical changes in the environment to produce harmful compounds. Therefore, waste liquid containing metal nitrates cannot be discharged into the environment. The present disclosure relates to a method for recovering and reusing metals from waste metal nitrate solutions.

[0033] A method for recovering useful metals from a nitrate solution of a metal cation or a metal oxycation can include the following steps. That is, adding the nitrate solution dropwise to a production column having an inlet and an outlet nozzle, the production column containing a circulating solution containing a base selected from the group consisting of ammonia, ammonium hydroxide, alkali metal hydroxides, and alkaline earth metal hydroxides, reacting the nitrates in the nitrate solution with the base in the circulating solution to produce a metal oxide salt or a metal hydroxide salt as a precipitate, discharging the precipitate and the circulating solution through the outlet nozzle of the production column, collecting the precipitate with a basket disposed below the production column while recovering the circulating solution with a recovery tank disposed below the basket, and pumping the recovered circulating solution from the recovery tank back to the production column. Here, referring to the drawings, like numbers indicate like components or steps, and broad aspects of various exemplary embodiments are disclosed.

[0034] Figure 1 shows a system for recovering useful metals from a solution of a nitrate of a metal cation or a metal oxycation. The system includes a recovery station 100. The recovery station 100 has a production column 1 with an inlet 3 and an outlet nozzle 2. The inlet 3 carries the nitrate solution to the production column 1, and the nitrate solution is dripped into the production column 1 through the inlet 3. The production column 1 contains a circulating solution containing a base. The nitrate in the nitrate solution reacts with the base in the circulating solution to produce an oxide salt or a metal hydroxide salt as a precipitate. The precipitate and the circulating solution exit the production column 1 through the outlet nozzle 2. The precipitate is collected in a basket 5 below the production column 1, and the circulating solution is recovered in a recovery tank 6 below the basket 5. The recovered circulating solution is pumped from the recovery tank 6 to the production column 1 by a pump 4.

[0035] In various embodiments, the production column contains a circulating solution containing, as the base, ammonia, ammonium hydroxide, lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, or magnesium hydroxide.

[0036] The production column may contain a circulating solution containing, as the base, ammonia or ammonium hydroxide. The base reacts with the oxide salt or the metal hydroxide salt to precipitate a metal oxide salt or a metal hydroxide salt.

[0037] In various embodiments, the nitrate solution contains the following nitrates. It is a cation or oxycation of a main group metal (e.g., a Group 2 metal such as magnesium or calcium, a Group 13 metal such as gallium or indium, a Group 14 metal such as tin or lead, a Group 15 metal such as bismuth, or a Group 16 metal such as tellurium), a cation or oxycation of a transition metal (e.g., yttrium, zirconium, zinc, or iron), a cation or oxycation of a lanthanide metal (e.g., cerium), or a cation or oxycation of an actinide metal (e.g., thorium, uranium, or plutonium).

[0038] In various embodiments, the nitrate is iron(III) nitrate. The product column contains a circulating solution containing ammonium hydroxide as a base, and the base reacts with the iron(III) nitrate salt to precipitate iron(III) hydroxide.

[0039] In various embodiments, the nitrate is yttrium(III) nitrate. The product column contains a circulating solution containing ammonium hydroxide as a base, and the base reacts with the yttrium(III) nitrate salt to precipitate yttrium(III) hydroxide.

[0040] In various embodiments, the nitrate is a nitrate of a radioactive metal cation or oxycation, such as uranyl nitrate, thorium nitrate, or plutonium nitrate. The product column can contain a circulating solution containing an alkali metal hydroxide, an alkaline earth metal hydroxide, an ammonium hydroxide salt, or ammonia as a base. The base reacts with the nitrate to precipitate a salt of the radioactive metal cation or oxycation.

[0041] In various embodiments, the nitrate is uranyl nitrate, and the product column may contain a circulating solution containing an ammonium hydroxide salt or ammonia as a base. The base reacts with uranyl nitrate to precipitate ammonium diuranate of the formula (NH4)2U2O7.

[0042] In various embodiments, the nitrate is uranyl nitrate, and the product column may contain a circulating solution containing an alkali metal hydroxide M 1 OH as a base. The base reacts with uranyl nitrate to precipitate an alkali metal diuranate of the formula M 1 2U2O7.

[0043] In various embodiments, the nitrate is uranyl nitrate, and the product column may contain a circulating solution containing an alkaline earth metal hydroxide M 2 (OH)2 as a base. The base reacts with uranyl nitrate to precipitate an alkaline earth metal diuranate of the formula M 2 U2O7.

[0044] The following discussion focuses on the recovery of uranium from uranyl nitrate solutions. In the uranium recovery system shown in Figure 1, uranium is recovered from a nitrate solution of a metal cation or a metal oxycation. This system includes a recovery station 100. The recovery station 100 has a production column 1 with an inlet 3 and an outlet nozzle 2. The inlet 3 transports the uranyl nitrate solution to the production column 1, and the uranyl nitrate solution is dripped into the production column 1 through the inlet 3. The production column 1 contains a circulating solution containing a base. The uranyl nitrate in the uranyl nitrate solution reacts with the base in the circulating solution to produce ammonium diuranate as a precipitate. For example, when the base is ammonium hydroxide or ammonia, ammonium diuranate is obtained as a precipitate. The precipitate of ammonium diuranate and the circulating solution are discharged from the production column through the outlet nozzle 2. The precipitate is collected in a basket 5 placed under the production column 1, while the circulating solution is recovered in a recovery tank 6 placed under the basket 5. The recovered circulating solution is then sent from the recovery tank 6 to the production column 1 by a pump 4.

[0045] In embodiments where the nitrate is a nitrate of a radioactive metal cation or oxycation, it is desirable to provide a production column 1 with an outer diameter of 4.5 inches or less, 4 inches or less, 3 inches or less, or 2 to 4.5 inches to avoid a criticality event. In embodiments where the nitrate is a nitrate of a non-radioactive metal cation production column 1, a larger diameter can be used if desired.

[0046] The recovery system shown in Figure 1 may include a cleaning station 200. The basket 5 containing the recovered precipitate is transported to the cleaning station 200 and placed above a cleaning tank 7. An aqueous cleaning solution is circulated from the cleaning tank 7 by a pump 8 to an outlet above the basket 5. The cleaning solution then passes through the basket 5 and cleans the precipitate.

[0047] The boundaries of the recovery station 100 are defined by barriers 12 and 13. The boundaries of the cleaning station 200 are defined by barriers 13 and 14. As will be described later, the basket 5 can be suspended above the collection tank 6 and / or the cleaning tank 7 using rails or cables 15.

[0048] In various embodiments, the uranium recovery system may include a drying station 300. The basket 5 containing the washed precipitate is transported to the drying station 300 and suspended from the hook or loop 9 of the drying rack 10. The drying rack suspends the basket above the receiving tray 11.

[0049] Once the precipitate in the basket has dried, the basket 5 containing the dried precipitate is moved to the furnace.

[0050] As shown in FIG. 2, the basket 5 includes a porous material 23 formed of a material stable at temperatures from 500°C to 800°C. Suitable materials include stainless steel, titanium, molybdenum, titanium zirconium molybdenum alloy, nickel, tantalum, tungsten, nickel, nickel chromium alloy, and alloys thereof. The porous material 23 can be a mesh of wires formed from a metal or metal alloy. In various embodiments, the porous material 23 may be a perforated metal sheet formed from a metal or metal alloy. The porous material 23 may be a fabric or mesh formed from carbon fibers, ceramic fibers, or threads formed from such fibers.

[0051] The basket 5 includes a non-porous material 22 formed of a metal stable at temperatures from 500°C to 800°C, such as stainless steel, titanium, molybdenum, titanium zirconium molybdenum alloy, nickel, tantalum, tungsten, nickel, nickel chromium alloy, and alloys thereof. The non-porous material 22 adds rigidity to the basket 5.

[0052] The basket 5 may include an upper portion 21 with a hook or flange 21a. The hook or flange 21a may be configured to hang the basket 5 over the recovery tank 6 and the cleaning tank 7 by hooking onto a rail or cable 15 above the tanks 6 and 7. The hook or flange 21a may also be configured to hang the basket 5 over the tray 11 by hooking onto a hook or loop 9 of the drying rack 10.

[0053] Figure 3 shows a second embodiment of a system for recovering uranium from a uranyl nitrate solution. The uranium-deficient uranyl nitrate flows from the inlet 3 to the production column 1, which may be a glass or metal tube bolted to the uranyl nitrate recovery housing 31. The basket 5 is disposed within or above the recovery tank 6. The pump 4 pumps a base solution (e.g., an ammonium hydroxide solution) from the recovery tank 6 through the conduit 32 and into the production column 1 through the conduit 33. While the pump 4 is operating, a certain amount of the base solution is maintained within the production column 1. The uranium-deficient uranyl nitrate is dripped from the inlet 3 into the production column 1. The uranyl nitrate reacts with the base to form insoluble diuranate, which flows out of a nozzle (shown in Figure 1) at the bottom of the production column 1 together with the recirculating ammonium hydroxide solution. The insoluble diuranate is collected by the basket 5, and the ammonium hydroxide solution flows into the recovery tank 6 and is then pumped back into the production column 1.

[0054] The basket 5 is then moved to a position within or above the cleaning tank 7. The cleaning solution is sent by the pump 8 through the conduit 34 to an outlet at the top of the basket 5. The cleaning solution passes through the basket 5 and flows into the cleaning tank 7. The liquid within the cleaning tank 7 flows through the conduit 35 to the pump 8 and is recirculated back into the cleaning tank through the conduit 34. After cleaning, the cleaned basket 5 and its diuranate contents are moved to a drying station and stored on the tray 11 until the diuranate dries.

[0055] The basket 5 and its contents of dried diuranate are transferred to the recovery oxidation furnace 37. The recovery oxidation furnace 37 may be heated in various ways. The recovery oxidation furnace 37 may have a graphite wall that can be resistance-heated. The recovery oxidation furnace 37 may be heated by a conductive coil. The recovery oxidation furnace 37 may be heated by a high-temperature vertical tube furnace 36. The vertical tube furnace 36 may be equipped with a ceramic heating element such as a molybdenum disilicide (MoSi2) heating element. The vertical tube furnace 36 can reach a temperature of up to 1800 °C.

[0056] The precipitate is oxidized in the oxidation furnace. When the system converts a transition metal nitrate (e.g., iron(III) nitrate) to a transition metal oxide salt or transition metal hydroxide salt (e.g., iron(III) hydroxide) to recover the transition metal, this is heated to produce an oxide (e.g., iron(III) oxide). Similar procedures can also be applied to other actinide metal nitrates, lanthanide metal nitrates, and transition metal nitrates. For example, zirconium oxynitrate (ZrO(NO3)2), cerium nitrate (Ce(NO3)3), and yttrium nitrate (Υ(NO3)3) can react with ammonia or ammonium hydroxide to form a precipitate and be converted to an oxide by heating using the system shown in Figure 1 and / or Figure 2.

[0057] If the basket 5 contains ammonium diuranate, the temperature of the recovery oxidation furnace 37 is controlled based on the desired final product of the uranium oxide. When ammonium diuranate [(NH4)2U2O7] is heated from about 420 °C to 550 °C, the compound undergoes denitration and conversion to UO3. When ammonium diuranate is heated from about 550 °C to 850 °C, the compound is converted to an oxide having approximately the formula U3O8. However, such conversions occur under ideal circumstances, and usually, the final product is often a mixture or alloy of various uranium oxides such as UO2, U2O5, UO3, U3O8, UO2O2, or mixtures thereof. At temperatures above 900 °C, or above 1000 °C, ammonium diuranate has approximately the formula U8O21 may be converted into an oxide having

[0058] After the ammonium diuranate salt is converted into an oxide ceramic in the recovery oxidation furnace 37, the basket 5 containing the uranium oxide ceramic is transferred to the glove box 38 for cooling. When the basket 5 is cooled to the allowable temperature, the basket 5 is recovered through the path 41 and the uranium oxide content is recovered.

[0059] Although various embodiments have been described in detail in particular relation to certain aspects, it should be understood that the present invention is applicable to other embodiments and that the details may be varied in various obvious respects. As will be apparent to those skilled in the art, variations and modifications can be made within the spirit and scope of the present invention. Accordingly, the foregoing disclosure, description, and drawings are used for illustrative purposes only and do not limit the present invention in any way, which is defined only by the claims.

Claims

1. A method for recovering a useful metal from a solution of a nitrate of a metal cation or a metal oxycation, comprising: adding the nitrate solution dropwise from the inlet to a production column having an inlet and an outlet nozzle; the production column containing a circulating solution containing a base selected from the group consisting of ammonia, ammonium hydroxide, alkali metal hydroxides, and alkaline earth metal hydroxides; reacting the nitrate in the nitrate solution with the base in the circulating solution to form a precipitate as a metal oxide salt or a metal hydroxide salt; enabling the precipitate and the circulating solution to exit the production column through the outlet nozzle; collecting the precipitate in a basket disposed below the production column and recovering the circulating solution in a recovery tank disposed below the basket; pumping the recovered circulating solution from the recovery tank to the production column. A method comprising the above steps.

2. The method according to claim 1, wherein the nitrate is a salt of a cation or oxycation of a main group metal, a transition metal, a lanthanide metal, or an actinide metal.

3. The method according to claim 1, wherein the nitrate is uranyl nitrate, thorium nitrate, or plutonium nitrate.

4. wherein the nitrate is uranyl nitrate; the base is ammonia or ammonium hydroxide; and the precipitate is ammonium diuranate, The method according to claim 3.

5. The method according to claim 4, wherein the base is ammonium hydroxide.

6. The method according to claim 3, wherein the nitrate is uranyl nitrate, the base is an alkali metal hydroxide, and the precipitate is an alkali metal diuranate.

7. further washing the precipitate with an aqueous cleaning solution; drying the washed precipitate; wherein the precipitate is held in the basket during the washing and drying steps, The method according to claim 1.

8. further moving the basket containing the collected precipitate from below the production column to an oxidation furnace; heating the basket containing the collected precipitate in the oxidation furnace to convert the precipitate to a metal oxide, The method according to claim 7.

9. wherein the nitrate is uranyl nitrate; the base is ammonia or ammonium hydroxide; and the precipitate is ammonium diuranate, The metal oxide is UO ２ 、U ２ O ５ 、UO ３ 、U ３ O ８ 、UO ２ O ２ 、or a mixture thereof The method according to claim 8.

10. The method according to claim 1, wherein the nitrate is iron(III) nitrate.

11. ​ The base is ammonium hydroxide The precipitate is hydroxide (III), The method according to claim 10.

12. The nitrate is yttrium (III) nitrate or cerium (III) nitrate, The method according to claim 1.

13. The base is ammonium hydroxide, The precipitate is yttrium (III) hydroxide or cerium (III) hydroxide, The method according to claim 12.

14. A system for recovering a useful metal from a solution of a nitrate of a metal cation or a metal oxycation, comprising: A production column having an inlet and an outlet nozzle, the inlet being a production column configured to drip a nitrate solution into the production column; A basket disposed under the outlet nozzle; A recovery tank disposed under the basket; and A recirculation system including a first pump and a flow path between the recovery tank and the production column, The first pump is configured to pump a circulating solution containing a base from the recovery tank to the production column; The recovery tank is configured to receive the circulating solution from the production column; The production column is configured such that the base in the circulating solution reacts with the nitrate solution to form a metal oxide salt as a precipitate; The outlet nozzle is configured such that the circulating solution and the precipitate exit the production column; The basket is configured to collect the precipitate, and the circulating solution flows into the recovery tank; System.

15. The method according to claim 14, wherein the nitrate is uranyl nitrate, thorium nitrate, or plutonium nitrate.

16. The nitrate is uranyl nitrate, the base is ammonia or ammonium hydroxide, and the precipitate is ammonium diuranate, The method according to claim 15.

17. A washing station; A washing liquid discharge port; A washing tank disposed under the washing liquid discharge port; A second pump; and Means for transporting the basket containing the collected precipitate from under the outlet nozzle to the washing station, wherein The second pump is configured to pump the washing liquid from the washing tank to the washing liquid discharge port to generate a flow of the washing liquid. The means for transporting is configured to place the basket under the cleaning liquid discharge port so that the collected precipitate is cleaned by the flow of the cleaning liquid. The system according to claim 14. Claim 18 An oxidation furnace, and means for transporting the basket containing the cleaned precipitate from the cleaning station to the oxidation furnace, further comprising, wherein the oxidation furnace is configured to convert the precipitate into a metal oxide. The system according to claim 14. Claim 19 The nitrate is uranyl nitrate, the base is ammonia or ammonium hydroxide, the precipitate is ammonium diuranate, and the oxidation furnace is configured to convert the precipitate into uranium oxide. The system according to claim 18.

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