ONE-STEP METHOD FOR ELECTROKINETIC URANIUM EXTRACTION AND SEPARATION FROM SANDSTONE-TYPE URANIUM DEPOSIT

Abstract

A one-step method for electrokinetic uranium extraction and separation from sandstone-type uranium deposit is provided, including: using an activating leaching agent to adjust pH of activation environment as pH3, converting uranium elements in sandstone-type uranium deposit into positively charged uranyl and its complexes; applying direct current (DC) electric field with voltage gradient of 0.1 V/cm to 2 V/cm between cathode and anode, and allowing the uranium elements to move toward a cathode chamber under the action of the electric field and to undergo selective reduction by receiving electrons to produce a low-valent insoluble uranium-containing substance precipitated on the cathode surface. The present invention, through activating leaching, allows the formation of positively charged uranium ions and their complexes only, and electrophysical effects such as electromigration and electroosmosis promote directional movement of uranium toward cathode, thereby achieving uranium extraction from a sandstone-type uranium deposit.

Claims

1. A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, the method comprising: uranium activation: using an activating leaching agent to adjust a pH of an activation environment as pH3, converting uranium elements in the sandstone-type uranium deposit into positively charged uranyl and its complexes; wherein the activating leaching agent is a mixture of FeCl.sub.3 and a chlorine-containing inorganic acid; a solid-liquid ratio of the sandstone-type uranium deposit to the activating leaching agent is 1 kg: 1-10 L, and a concentration of FeCl.sub.3 in the activating leaching agent is 10 g/L to 20 g/L; electric field drive: introducing an activated sandstone-type uranium deposit into a direct current (DC) electric field, applying a DC electric field with a voltage gradient of 0.1 V/cm to 0.5 V/cm between a cathode and an anode, and allowing the uranium elements to move toward a cathode chamber (4) under an action of the electric field and thus to be directionally enriched in the cathode chamber (4); electrode selective reduction and fixation of uranium: both the cathode and the anode being conductive plastic electrodes, allowing selective reduction of the positively charged uranium elements on a surface of the cathode conductive plastic electrode (2) by electrochemically reducing them to a low-valent insoluble uranium-containing substance and precipitating it on the surface of the cathode conductive plastic electrode (2), such that the uranium-containing precipitate is collected on the surface of the cathode conductive plastic electrode (2).

2. The one-step method for electrokinetic uranium extraction and separation from the sandstone-type uranium deposit according to claim 1, wherein the solid-liquid ratio of the sandstone-type uranium deposit to the activating leaching agent 1 kg: 5-10 L.

3. The one-step method for electrokinetic uranium extraction and separation from the sandstone-type uranium deposit according to claim 1, wherein a pH of the activating leaching agent is 0.5-3.

4. The one-step method for electrokinetic uranium extraction and separation from the sandstone-type uranium deposit according to claim 3, wherein the pH of the activating leaching agent is 0.5-1.

5. The one-step method for electrokinetic uranium extraction and separation from the sandstone-type uranium deposit according to claim 1, wherein the chlorine-containing inorganic acid is selected from any one or more of HCl, HClO, and HClO.sub.4.

6. The one-step method for electrokinetic uranium extraction and separation from the sandstone-type uranium deposit according to claim 1, wherein after adding the activating leaching agent, the sandstone-type uranium deposit is activated at a temperature of 0-40 C. for 1-24 hours, and then a direct current with a voltage gradient of 0.1 V/cm to 0.5 V/cm is applied between the cathode and the anode for 1-24 hours.

7. The one-step method for electrokinetic uranium extraction and separation from the sandstone-type uranium deposit according to claim 1, wherein the sandstone-type uranium deposit is separated from the cathode conductive plastic electrode (2) and the anode conductive plastic electrode (3) by a cathode filter (6) and a anode filter (7) respectively to form the cathode chamber (4) and an anode chamber (5), and the uranium elements enter the cathode chamber through the cathode filter (6); and, the cathode filter (6) and the anode filter (7) are both nylon filters; and, a mesh size of the cathode filter (6) and a mesh size of the anode filter (7) are both 400 mesh.

8. The one-step method for electrokinetic uranium extraction and separation from the sandstone-type uranium deposit according to claim 2, wherein the sandstone-type uranium deposit is separated from the cathode conductive plastic electrode (2) and the anode conductive plastic electrode (3) by a cathode filter (6) and a anode filter (7) respectively to form the cathode chamber (4) and an anode chamber (5), and the uranium elements enter the cathode chamber through the cathode filter (6); and, the cathode filter (6) and the anode filter (7) are both nylon filters; and, a mesh size of the cathode filter (6) and a mesh size of the anode filter (7) are both 400 mesh.

9. The one-step method for electrokinetic uranium extraction and separation from the sandstone-type uranium deposit according to claim 3, wherein the sandstone-type uranium deposit is separated from the cathode conductive plastic electrode (2) and the anode conductive plastic electrode (3) by a cathode filter (6) and a anode filter (7) respectively to form the cathode chamber (4) and an anode chamber (5), and the uranium elements enter the cathode chamber through the cathode filter (6); and, the cathode filter (6) and the anode filter (7) are both nylon filters; and, a mesh size of the cathode filter (6) and a mesh size of the anode filter (7) are both 400 mesh.

10. The one-step method for electrokinetic uranium extraction and separation from the sandstone-type uranium deposit according to claim 4, wherein the sandstone-type uranium deposit is separated from the cathode conductive plastic electrode (2) and the anode conductive plastic electrode (3) by a cathode filter (6) and a anode filter (7) respectively to form the cathode chamber (4) and an anode chamber (5), and the uranium elements enter the cathode chamber through the cathode filter (6); and, the cathode filter (6) and the anode filter (7) are both nylon filters; and, a mesh size of the cathode filter (6) and a mesh size of the anode filter (7) are both 400 mesh.

11. The one-step method for electrokinetic uranium extraction and separation from the sandstone-type uranium deposit according to claim 5, wherein the sandstone-type uranium deposit is separated from the cathode conductive plastic electrode (2) and the anode conductive plastic electrode (3) by a cathode filter (6) and a anode filter (7) respectively to form the cathode chamber (4) and an anode chamber (5), and the uranium elements enter the cathode chamber through the cathode filter (6); and, the cathode filter (6) and the anode filter (7) are both nylon filters; and, a mesh size of the cathode filter (6) and a mesh size of the anode filter (7) are both 400 mesh.

12. The one-step method for electrokinetic uranium extraction and separation from the sandstone-type uranium deposit according to claim 6, wherein the sandstone-type uranium deposit is separated from the cathode conductive plastic electrode (2) and the anode conductive plastic electrode (3) by a cathode filter (6) and a anode filter (7) respectively to form the cathode chamber (4) and an anode chamber (5), and the uranium elements enter the cathode chamber through the cathode filter (6); and, the cathode filter (6) and the anode filter (7) are both nylon filters; and, a mesh size of the cathode filter (6) and a mesh size of the anode filter (7) are both 400 mesh.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 is a flow chart showing a one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit according to the present invention.

[0036] FIG. 2 is a schematic diagram showing the one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit according to the present invention.

[0037] FIG. 3 is a diagram showing a phase equilibrium analysis of uranium deposit under different pH according to the present invention.

[0038] Reference numeral: power supply1; cathode conductive plastic electrode2; anode conductive plastic electrode3; cathode chamber4; anode chamber5; cathode filter6; anode filter7; sandstone-type uranium deposit8.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts are within the scope of protection of the present invention.

[0040] It should be noted that if specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0041] Throughout the present invention, all features, such as values, amounts, contents, and concentrations, specified in numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible subranges and individual values within those ranges.

[0042] The features described in the present invention may be combined in any manner, and as long as there are no conflicts between the combinations of these features, all possible combinations should be considered within the scope of the present specification. Each feature disclosed in the present specification may be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the features disclosed are merely general examples of equivalent or similar features.

[0043] Currently, sulfuric acid is the most common leaching agent used to extract uranium from uranium deposit. However, the use of sulfuric acid cause the coexistence of positively charged UO.sub.2.sup.2+ and negatively charged UO.sub.2(X).sub.2.sup.2 and UO.sub.2(X).sub.3.sup.4 particles. Due to their varying charge properties, their migration directions in the electric field also differ, making it impossible to achieve directional and controllable collection of uranium. Furthermore, the use of H.sub.2SO.sub.4 is prone to reaction to generate insoluble matters that block the leaching channels. In addition, the final products are all uranium-containing leachates, which require further processing to remove impurities and refine the uranium. Uranium leachates have complicated compositions, causing the problems of high technical difficulty, complex process, and high cost in uranium purification.

[0044] Therefore, the present invention provides a one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit. Referring to FIG. 1, the uranium activation, electric drive, and selective reduction technologies are combined together. The uranium in the sandstone-type uranium deposit is converted into positively charged uranium, so that it moves toward the cathode conductive plastic electrode 2 under the action of an electric field and then electrically reduced at the cathode conductive plastic electrode 2 to convert the uranium into a low-valent insoluble uranium-containing substance that is precipitated on the surface of the cathode conductive plastic electrode 2, while other impurity metal ions are not precipitated on the surface of the cathode conductive plastic electrode 2 through hydroxides, thereby enriching uranium.

[0045] The present invention uses FeCl.sub.3+HCl as a leaching agent, combined with electric drive technology. FeCl.sub.3 not only provides Fe.sup.3+ to oxidize UO.sub.2 in the sandstone-type uranium deposit, but also provides Cl.sup. to form positively charged complex ions UO.sub.2Cl.sup.+ with uranyl ions. HCl also provides Cl.sup. while maintaining an acidic pH environment of sandstone-type uranium deposit. This allows only positively charged uranium complexes to form in the sandstone-type uranium deposit, rather than causing the uranium elements in the system to exist as both anions and cations. Thus, after applying an electric field, electrophysical effects such as electromigration and electroosmosis of positively charged uranium-containing particles including uranyl ions and uranyl complex cations can promote the rapid enrichment of uranium in the cathode chamber. Furthermore, under the action of the applied electric field, positively charged species migrate toward the cathode conductive plastic electrode 2, while negatively charged species migrate toward the anode conductive plastic electrode 3. As a result, the adsorption of positively charged uranium ions by negatively charged mineral particles is reduced, further improving the leaching rate of uranium. Furthermore, the energization process not only accelerates the flow of liquid within the deposit but also oxidizes tetravalent uranium that was not oxidized during the activation process, further increasing uranium dissolution. Under low pH and a suitable electric field, the positively charged uranium-containing particles enriched in the cathode chamber are selectively reduced by the cathode conductive plastic electrode, while simultaneously preventing the precipitation of other metallic impurity ions. The positively charged uranium-containing particles are then electrically reduced through electron transfer, resulting in a high-purity uranium-containing precipitate on the surface of the cathode conductive plastic electrode 2.

[0046] By using the activating leaching agent of the present invention, the uranium elements in the system exist in the forms of UO.sub.2.sup.2+, UO.sub.2Cl.sup.+ formed by the complexation of UO.sub.2.sup.2+ and Cl.sup., and positively charged particles such as (UO.sub.2).sub.2OH.sup.3+, (UO.sub.2).sub.2(OH).sub.2.sup.2+, (UO.sub.2).sub.3(OH).sub.4.sup.2+, and (UO.sub.2).sub.3(OH).sup.5+ produced by the hydrolysis of UO.sub.2.sup.2+.

[0047] In addition, the present invention conducted a phase equilibrium analysis in the study. When the pH reaches 4.2, the reaction system will start to produce uranyl hydroxide precipitation, which affects the leaching of uranium elements, referring to FIG. 3. In the technology of the present invention, although under acidic conditions, as the pH increases, the uranium content and impurity rate from cathode electroreduction will be affected. Therefore, the present invention controls the acidic environment to be pH3.

[0048] The conductive plastic electrodes used in the present invention are both electrically conductive and corrosion-resistant, making them particularly suitable for use in low-pH environments and enabling more economical extraction and purification of uranium elements from a sandstone-type uranium deposit. For example, the electrokinetic geosynthetic (EKG) electrodes described in Chinese Patent CN118724422A may be used, but other conductive plastic electrodes may also be used without being limited thereto.

[0049] The following is a detailed description of the one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit provided by the present invention through Embodiments 1 to 17.

Embodiment 1

[0050] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, the method including:

[0051] 5 L of the activating leaching agent FeCl.sub.3+HCl at the pH of 3 is continuously introduced into 1 kg of the sandstone-type uranium deposit with a uranium concentration of 400 g/g, where the FeCl.sub.3 concentration is 10 g/L, and the pH is adjusted with the HCl. During the activation process, some insoluble tetravalent uranium in the deposit is gradually converted into soluble hexavalent uranium, including UO.sub.2.sup.2+, UO.sub.2Cl.sup.+ formed by the complexation of UO.sub.2.sup.2+ and Cl.sup., and positively charged particles such as (UO.sub.2).sub.2OH.sup.3+, (UO.sub.2).sub.2(OH).sub.2.sup.2+, (UO.sub.2).sub.3(OH).sub.4.sup.2+, and (UO.sub.2).sub.3(OH).sup.5+ produced by the hydrolysis of UO.sub.2.sup.2+.

[0052] The cathode and anode are conductive plastic electrodes and electrically connected to the negative and positive electrodes of a power supply 1, respectively. A 400-mesh nylon anode filter 7 is placed between the anode conductive plastic electrode 3 and the sandstone-type uranium deposit 8, forming an anode chamber 5. A 400-mesh nylon cathode filter 6 is placed between the sandstone-type uranium deposit 8 and the cathode conductive plastic electrode 2, forming a cathode chamber 4, as shown in FIG. 2. After 24 hours of activation, a stable direct current with a voltage gradient of 0.5 V/cm is introduced for 24 hours. This current not only accelerates the flow of liquid within the deposit but also oxidizes tetravalent uranium that was not oxidized during the activation process, further enhancing uranium dissolution. Uranium elements first electrochemically migrate to the cathode conductive plastic electrode 2 in the form of positively charged particles. Subsequently, uranium elements are selectively reduced on the surface of the cathode conductive plastic electrode 2. Through charge transfer between the electrode surface and the charged particles, hexavalent uranium in the positively charged uranium-containing particles is electrochemically reduced to tetravalent uranium, which precipitates on the surface of the cathode conductive plastic electrode 2 as UO.sub.2. After the power was turned off, elution and measurement are conducted, and it is found that the uranium attached to the cathode conductive plastic electrode 2 weighs 307.6 mg, accounting for 76.9% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 2

[0053] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 1, except that:

[0054] The pH of the activating leaching agent used is 2. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 337.2 mg, accounting for 84.3% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 3

[0055] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 1, except that:

[0056] The pH of the activating leaching agent used is 1. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 350.0 mg, accounting for 87.5% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 4

[0057] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 1, except that:

[0058] The pH of the activating leaching agent used is 0.5. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 356.8 mg, accounting for 89.2% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 5

[0059] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 2, except that:

[0060] The volume of the activating leaching agent FeCl.sub.3+HCl used is 1 L. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 261.6 mg, accounting for 65.4% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 6

[0061] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 5, except that:

[0062] The volume of the activating leaching agent FeCl.sub.3+HCl used is 3 L. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 289.2 mg, accounting for 72.3% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 7

[0063] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 5, except that:

[0064] The volume of the activating leaching agent FeCl.sub.3+HCl used is 8 L. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 345.2 mg, accounting for 86.3% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 8

[0065] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 5, except that:

[0066] The volume of the activating leaching agent FeCl.sub.3+HCl used is 10 L. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 360.4 mg, accounting for 90.1% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 9

[0067] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 2, except that:

[0068] The concentration of the FeCl.sub.3 in the activating leaching agent used is 15 g/L. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 348.8 mg, accounting for 87.2% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 10

[0069] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 9, except that:

[0070] The concentration of the FeCl.sub.3 in the activating leaching agent used is 20 g/L. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 357.2 mg, accounting for 89.3% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 11

[0071] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 2, except that:

[0072] The voltage gradient applied between the cathode and anode electrodes is 0.1 V/cm. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 281.2 mg, accounting for 70.3% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 12

[0073] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 11, except that:

[0074] The voltage gradient applied between the cathode and anode electrodes is 0.2 V/cm. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 298.0 mg, accounting for 74.5% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 13

[0075] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 11, except that:

[0076] The voltage gradient applied between the cathode and anode electrodes is 0.3 V/cm. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 316.8 mg, accounting for 79.2% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 14

[0077] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 11, except that:

[0078] The voltage gradient applied between the cathode and anode electrodes is 0.4 V/cm. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 323.6 mg, accounting for 80.9% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 15

[0079] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 2, except that:

[0080] The voltage gradient applied between the cathode and anode electrodes is 1.0 V/cm. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 327.6 mg, accounting for 81.9% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 16

[0081] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 15, except that:

[0082] The voltage gradient applied between the cathode and anode electrodes is 1.5 V/cm. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 314.4 mg, accounting for 78.6% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

Embodiment 17

[0083] A one-step method for electrokinetic uranium extraction and separation from a sandstone-type uranium deposit, basically the same as that in Embodiment 15, except that:

[0084] The voltage gradient applied between the cathode and anode electrodes is 2.0 V/cm. It is finally found that the uranium attached to the cathode conductive plastic electrode 2 weighs 265.2 mg, accounting for 66.3% of the total uranium content of the sandstone-type uranium deposit used in the experiment.

[0085] Table 1 shows the conditions of various embodiments of the present invention and the amount of uranium electro-reduced by the cathode conductive plastic electrode

TABLE-US-00001 Percentage of FeCl.sub.3 Activating Electrokinetic Voltage uranium electro- Solid-liquid pH concentration extraction extraction gradient reduced by Impurity Embodiment ratio(kg:L) value (g/L) time(h) time(h) (V/cm) cathode(%) rate 1 1:5 3 10 24 24 0.5 76.9% 1.6% 2 1:5 2 10 24 24 0.5 84.3% 1.3% 3 1:5 1 10 24 24 0.5 87.5% 0.6% 4 1:5 0.5 10 24 24 0.5 89.2% 0.3% 5 1:1 2 10 24 24 0.5 65.4% 4.5% 6 1:3 2 10 24 24 0.5 72.3% 2.1% 7 1:8 2 10 24 24 0.5 86.3% 1.0% 8 1:10 2 10 24 24 0.5 90.1% 0.8% 9 1:5 2 15 24 24 0.5 87.2% 1.1% 10 1:5 2 20 24 24 0.5 89.3% 0.9% 11 1:5 2 10 24 24 0.3 70.3% 0.4% 12 1:5 2 10 24 24 0.2 74.5% 0.6% 13 1:5 2 10 24 24 0.3 79.2% 0.7% 14 1:5 2 10 24 24 0.4 80.9% 1.1% 15 1:5 2 10 24 24 1.0 81.9% 10.4% 16 1:5 2 10 24 24 1.5 78.6% 16.2% 17 1:5 2 10 24 24 2.0 66.3% 21.3%

[0086] As can be seen from Table 1, in Embodiments 1-4, when the solid-liquid ratio is 1:5, the FeCl.sub.3 concentration is 10 g/L, the activation extraction time is 24 h, and then the electrokinetic extraction time is 24 h under the voltage gradient of 0.5 V/cm, the amount of uranium precipitated on the cathode conductive plastic electrode 2 by electroreduction increases as the pH value decreases, with reduced impurity rate and improved uranium purity. The solid-liquid ratio of Embodiment 2 is different from those of Embodiments 5-8, as the solid-liquid ratio decreases, the amount of uranium precipitated by electroreduction gradually increases and the impurity rate decreases. The FeCl.sub.3 concentration of Embodiment 2 is different from those of Embodiments 9 and 10, trivalent iron ions function as the oxidant for tetravalent uranium in the activation process, as the FeCl.sub.3 concentration increases, the amount of uranium precipitated by electroreduction gradually increases and the impurity rate decreases. The voltage gradient of Embodiment 2 is different from those of Embodiments 11-17, as the voltage gradient increases within the range of 0.1 V/cm to 0.5 V/cm, the amount of uranium precipitated by electroreduction significantly increases, and the content of other impurity elements in the precipitate on the cathode surface is relatively low, that is, at the low voltage gradient of 0.1 V/cm to 0.5 V/cm, applying the present invention to perform one-step electrokinetic extraction from a sandstone-type uranium deposit cam produce a high-purity uranium-containing precipitate on the cathode. Embodiments 15-17 show the extraction and separation effects at a higher voltage gradient, at a high voltage gradient, the amount of uranium precipitated by electroreduction on the cathode surface significantly decreases with the increase of the voltage gradient, and the impurity rate also increases, which may be caused by the change in system pH due to electrolysis. Therefore, in practical applications, it is necessary to take into consideration the electrolysis situation at a high voltage gradient. The intense electrolysis of the cathode causes the significant increase in pH of the cathode liquid and triggers the formation of a large amount of hydroxide precipitation of other metal elements. They precipitate into the cathode liquid or adhere to the cathode surface, reducing the uranium extraction rate and purity. However, using a low voltage gradient can achieve high and pure uranium extraction and separation effects while saving electricity.

[0087] At the same pH, the activating leaching agent of the present invention requires less amount of HCl compared to uranium leaching with H.sub.2SO.sub.4. The present invention utilizes HCl+FeCl.sub.3 as the activating leaching agent, resulting in the formation of only positively charged uranium complexes in the sandstone-type uranium deposit. Under the action of electric current, the adsorption of uranium ions by mineral particles is reduced, further improving the leaching rate of uranium. High-valent uranium complexes undergo electrophysical effects such as electromigration and electroosmosis, migrating continuously toward the cathode chamber and being selectively reduced on the surface of the cathode conductive plastic electrode. Furthermore, in the present invention, the initial pH of the reaction system is controlled to be low, and the electric field strength is controlled to weaken the electrolysis. Therefore, when the cathode receives electrons and undergoes an electrically-induced reduction, high-valent uranium cations can be reduced to low-valent insoluble uranium and fixed on the electrode surface, while other impurity metal ions will not be precipitated on the cathode surface through hydroxides. At the same time, uranium has a high reduction potential and is reduced and fixed on the surface of the cathode conductive plastic electrode prior to other impurity metal ions, which is beneficial to improving the purity of the enriched uranium and realizing the one-step method for electrokinetic uranium extraction and separation.

[0088] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.