A method for extracting uranium trioxide from boundary grade uranium ore based on agitation leaching

Abstract

The invention discloses a method for extracting U3O8 from a boundary grade ore based on stirring leaching, the method comprising the following steps: 1) ore grinding; 2) stirring leaching; 3) ore classification; 4) ion exchange adsorption of uranium from fine mud pulp; 5) leaching a resin loaded with uranium; 6) enriching uranium by extraction-stripping of the leaching solution; 7) precipitating ammonium diuranate from the stripping solution; 8) calcining the ammonium diuranate to obtain U3O8. The method can effectively reduce the energy consumption in the process of ore grinding and solid-liquid separation while effectively leaching the boundary grade uranium ore, and reduce the raw material consumption by leaching the coarse particle ore and recycling the efficient raw materials and solutions, thereby realizing the economic recovery of uranium in the boundary grade uranium ore.

Description

Technical Field

[0001] The invention relates to a method for processing uranium ore, in particular to a method for extracting U3O8 from boundary grade uranium ore based on stirring leaching, and belongs to the technical field of uranium ore hydrometallurgy. Background Art

[0002] Among the hard rock uranium resources, the lowest industrial grade is 0.05%, and 0.03% is the boundary grade. At present, no uranium mines with boundary grades have been developed in China. For such uranium-containing ores with boundary grades or lower than the boundary grade, the uranium in the ore is generally enriched through mineral processing to reach a higher grade to meet the conditions for economic mining before development; or when such uranium resources are co-existing with other valuable polymetallics, uranium and other valuable leaching are comprehensively extracted to improve the economic benefits of ore development; or low-grade uranium resources co-existing with polymetallics are processed by mineral processing, and useful elements are grouped and processed separately. Different uranium ores have different mineral processing properties. The uranium distribution in some ores is relatively dispersed, and it is impossible to group or enrich the valuable elements in them by mineral processing or other methods.

[0003] For the direct treatment of low-grade hard rock uranium ore, the heap leaching process is often used. Generally speaking, the processing cost of the heap leaching process is lower than that of agitation leaching, which can improve the economic benefits of the development of low-grade uranium ore. However, agitation leaching still has its irreplaceable advantages. Generally speaking, heap leaching has high requirements for the permeability of the ore, and not all ores are suitable for heap leaching. Compared with heap leaching, agitation leaching has higher mass transfer efficiency, shorter leaching time, and a smaller footprint for equipment and facilities. In arid and water-scarce areas, agitation leaching has the advantages of using less water than heap leaching.

[0004] At present, it is difficult to directly process boundary grade uranium ore by agitation leaching process due to production cost. Compared with heap leaching, the cost of agitation leaching is mainly increased in ore grinding and solid-liquid separation. If the cost of the above processes can be reduced as much as possible, the economic efficiency of agitation leaching process will be greatly improved. Summary of the invention

[0005] In view of the technical problems of high cost and low uranium recovery rate in the process of treating boundary grade uranium ore by stirring leaching process in the prior art, the purpose of the present invention is to provide a method for extracting uranium from boundary grade uranium ore and preparing U3O8 by stirring leaching. The method combines stirring leaching, leaching slurry classification, uranium adsorption by ion exchange of slurry, extraction-strip extraction, precipitation and calcination, etc., which can not only effectively leach and recover uranium in boundary grade uranium ore and obtain U3O8 product with higher purity, but also reduce the cost of ore crushing, leaching, solid-liquid separation and metal recovery in the process of stirring leaching of boundary grade uranium ore, so that uranium in boundary grade ore can be economically recovered, and the whole process realizes the recycling of intermediate waste liquid and gas products, reduces costs and reduces environmental pollution.

[0006] In order to achieve the above technical objectives, the present invention provides a method for extracting U3O8 from a boundary grade uranium ore based on stirring leaching, the method comprising the following steps:

[0007] 1) crushing and grinding the boundary grade uranium ore, and then stirring and leaching to obtain leaching slurry;

[0008] 2) Classifying the leached slurry to separate the fine mud slurry;

[0009] 3) After the fine mud slurry is subjected to uranium adsorption by ion exchange resin, the uranium-loaded resin is screened out;

[0010] 4) eluting the uranium-loaded resin with dilute acid, and extracting and stripping the resulting eluent to obtain a uranium-containing solution;

[0011] 5) passing ammonia gas into the uranium-containing solution for precipitation to obtain ammonium diuranate precipitate;

[0012] 6) Calcine the ammonium diuranate precipitate to obtain U3O8.

[0013] The technical solution of the present invention can effectively leach and recover uranium in boundary grade uranium ore and obtain U3O8 products with higher purity by combining processes such as stirring leaching, leaching slurry classification, slurry ion exchange adsorption of uranium, extraction-strip extraction, precipitation and calcination.

[0014] As a preferred solution, the boundary grade uranium ore is crushed and finely ground to a particle size of -2 mm, and the mass proportion of the uranium ore is not less than 80%.

[0015] As a preferred solution, the stirring leaching conditions are: the liquid-to-solid ratio of the slurry is 0.3:1L / kg to 0.5:1L / kg, the leaching agents are sulfuric acid and ferric sulfate, and the amount of ferric sulfate added is to control the Fe content in the slurry. 3+The concentration is 2g / L to 10g / L, the amount of sulfuric acid added is to control the pH value in the slurry to be 1 to 2, the leaching temperature is room temperature, and the leaching time is 30min to 30h. The technical solution of the present invention is key to the use of coarse-grained ore and high-concentration slurry in the process of stirring and leaching the boundary grade uranium ore. Compared with the conventional stirring and leaching, the ore particle size is generally controlled to be below 0.5mm. The leaching of coarse-grained ore can reduce the grinding cost and is beneficial to the subsequent ore classification. The stirring and leaching process of the high-concentration slurry can prevent the slurry from settling in the tank and reduce the consumption of reagents in the leaching process. The sulfuric acid of the present invention can be concentrated sulfuric acid with a mass percentage concentration greater than 85%. The introduction of ferric sulfate mainly utilizes trivalent iron ions to promote the leaching of uranium. The specific reaction formula is as follows: Fe2(SO4)3+UO2=UO2SO4+2FeSO4.

[0016] As a preferred solution, the classification particle size is 60 mesh. The coarse tailings can be directly discarded by classification of appropriate particle size, which is beneficial to the subsequent resin adsorption and separation process. The classification can use a hydrocyclone or a vibrating screen. The coarse sand washing adopts vacuum filtration, the washing liquid is the tail liquid or water produced by the adsorption of uranium, the washing water volume to the ore mass ratio is 2 to 3mL: 1g, the washing stage is 3 to 8, and generally the last stage washing adopts water.

[0017] As a preferred solution, during the classification process, the coarse sand obtained after separating the fine mud pulp is washed and transported to the tailings dam; the washing uses water or tailings generated during the uranium adsorption process, and the washing water obtained by washing is combined with the fine mud pulp for treatment. The coarse sand can be washed to recover a small amount of uranium carried by the coarse sand.

[0018] As a preferred solution, during the uranium adsorption process, Thiobacillus ferrooxidans is inoculated into the fine mud slurry, and air is blown into the fine mud slurry. During the ion exchange adsorption of uranium, ion exchange resin is directly added to the fine mud slurry for adsorption, and the sulfide in the ore and the Fe in the solution are oxidized by continuous blowing of air and biological means. 2+ Without adding any reagent, the uranium in the fine mud is further leached out, and the washing process of fine-particle minerals, which is the most energy-consuming in the solid-liquid separation process, is reduced. The fine mud slurry is generally subjected to ion exchange adsorption using a multi-stage tank ion exchange device. In the uranium adsorption process, thiobacillus ferrooxidans and air blowing are used to promote the removal of Fe in the ore. 2+ Oxidation and oxidation of sulfides in the ore to produce H + , so that the residual uranium in the fine-grained ore can be further leached. As the ion exchange continues to adsorb uranium, the uranium concentration in the pulp is reduced, which can promote the rapid entry of uranium in the fine-grained ore into the pulp. At the same time, the continuous introduction of oxygen can achieve the mixing of resin and pulp and the lifting and transfer of resin, thereby improving the uranium leaching and adsorption efficiency.

[0019] As a preferred solution, in the uranium adsorption process, the deuranium fine mud slurry obtained after screening and separating the loaded resin is subjected to flocculation and thickening treatment, the underflow is transported to the tailings dam, and the overflow is circulated to the stirring leaching or washing process. In the flocculation process, anionic, cationic, amphoteric or non-ionic organic polymer flocculants commonly used in the prior art can be used. The amount of flocculant added can be added according to actual conditions, and generally the amount added relative to the mass of each ton of raw ore is within 300g.

[0020] As a preferred solution, the dilute acid is dilute sulfuric acid with a concentration ranging from 5wt% to 15wt%.

[0021] As a preferred solution, the extraction uses an amine extractant. The amine extractant is preferably a secondary amine and / or a tertiary amine. The organic phase used for the extraction contains an extractant, and generally a modifier can also be added. The modifier can be one or more of alcohols such as sec-octanol, mixed alcohols, isopentanol, isodecanol, or esters such as TBP and TRPO. The volume fraction of the extractant in the organic phase is 2% to 10%, the volume fraction of the modifier in the organic phase is 0 to 20%, and the solvent in the organic phase is sulfonated kerosene.

[0022] As a preferred solution, the stripping uses ammonium sulfate solution and ammonia water stripping agent, and the pH of the stripping end point is controlled to be 4 to 4.5. The concentration of the ammonium sulfate solution is 80 to 200 g / L. The amount of ammonia water added is to control the pH of the stripping end point.

[0023] As a preferred solution, the raffinate generated during the extraction process is recycled to the elution process for use.

[0024] As a preferred solution, ammonia gas generated during the calcination process is recycled to the precipitation process for use.

[0025] The method for extracting U3O8 from boundary grade uranium ore provided by the present invention comprises the following steps:

[0026] (1) Ore crushing and grinding: The mass percentage of boundary grade uranium ore crushed and ground to -2 mm particle size shall not be less than 80%.

[0027] (2) Leaching: The ore in the above step (1) is subjected to stirring leaching; wherein: sulfuric acid and / or ferric sulfate are used as leaching agents, the solid volume mass ratio (L / kg) of the leaching solution is 0.3-0.5, the leaching temperature is room temperature, the leaching time is 30 min-30 h, the leaching agents are sulfuric acid and ferric sulfate, and the amount of ferric sulfate added is to control the Fe content of the leaching process. 3+ The concentration is 2g / L to 10g / L, and the amount of sulfuric acid (concentration greater than 85%) added is to ensure that the pH value of the leaching process is 1 to 2. The above process is carried out at room temperature, and the leaching time is 30min to 30h.

[0028] (3) Ore classification: After leaching in step (2), the ore pulp is usually classified by a hydrocyclone or a vibrating screen. The ore classification particle size is 60 mesh. The coarse sand is washed by vacuum filtration. The washing liquid is the adsorption tail liquid. The ratio of the washing water volume to the ore mass is 2 to 3:1. The number of washing stages is 3 to 8.

[0029] (4) Ion exchange adsorption of uranium by fine mud slurry: The fine mud slurry obtained in step (3) above is combined with the coarse sand washing liquid and then used in a multi-stage tank ion exchange device to adsorb uranium. The resin is an anion exchange resin (e.g., 201×7, D201, D231, 301, etc.). During the adsorption process, Thiobacillus ferrooxidans is inoculated, and air is blown in to achieve mixing of the resin and the slurry and lifting and transfer of the resin. After the adsorption is completed, the resin and the fine mud slurry are screened by a 60-mesh vibrating screen. During the adsorption process, uranium is continuously adsorbed by the resin to reduce the uranium concentration in the water, and the Fe is promoted by Thiobacillus ferrooxidans. 2+ Oxidation, oxidation of sulfides in ores and production of H + , so that the uranium in the fine-particle ore can be further leached in this process; in the sedimentation process of fine mud slurry after adsorption, the amount of flocculant added is 0-300g / based on the mass of the original ore, and the flocculant can be anionic, cationic, amphoteric or non-ionic organic polymer flocculant; the underflow is transported to the tailings dam, and the overflow is returned to the leaching and washing process for recycling.

[0030] (5) Elution: The loaded resin obtained after separation by the vibrating screen in the above step (4) is eluted with 5 wt% to 15 wt% dilute sulfuric acid to obtain lean resin and eluent.

[0031] (6) Extraction: Extracting the eluent in step (5), using an amine extractant, which may be a primary amine, a secondary amine or a tertiary amine, and using one or more alcohols such as sec-octanol, mixed alcohols, isopentanol, isodecanol or esters such as TBP and TRPO as modifiers, with the volume fraction of the extractant being 2% to 10%, the volume fraction of the modifier being 0 to 20%, and the solvent system being sulfonated kerosene. The extraction test is carried out in a box-type mixer-settler or a centrifugal extractant, the extraction temperature being room temperature to 40° C., the two-phase contact time being 1 min to 10 min, and the flow ratio of the eluent to the extractant being 0.3 to 3:1. After the extraction, raffinate water and an organic phase loaded with uranium are obtained, and sulfuric acid is added to the raffinate water and returned to step (5) for use as an eluent.

[0032] (7) Stripping: In the above step (6), the organic phase loaded with uranium is treated with ammonium sulfate, and the concentration of ammonium sulfate is 80-200 g / L. Ammonia water is added during the stripping process to control the end point pH to 4-4.5, to obtain a stripping solution and a lean organic phase, and the lean organic phase is returned to (6) to extract uranium.

[0033] (8) Precipitation: The stripping solution obtained in step (7) is passed through ammonia gas to precipitate ammonium diuranate. After the ammonium diuranate is filtered and washed, ammonium diuranate and precipitation mother liquor are obtained. The mother liquor is returned to step (6) for stripping.

[0034] (9) Calcination: In the above step (8), the ammonium diuranate is calcined at 750-850° C. for 2-8 hours to obtain a U3O8 product. The ammonia generated during the calcination process is returned to (8) and used as a precipitant.

[0035] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0036] The present invention uses a stirring leaching process to leach uranium in boundary grade uranium ore and obtain U3O8 products, which not only realizes the efficient recovery of uranium in boundary grade uranium ore with a recovery rate of more than 81%, but also can reduce the energy consumption of processes such as grinding and leaching solid-liquid separation in the process of processing boundary grade uranium ore. The power consumption in the overall ore processing process is less than 20kwh. In the process of recovering uranium, solutions and ammonia in various process systems can be recycled, which effectively reduces reagent consumption and greatly reduces the cost of the uranium recovery process. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The principle flow of the method for extracting U3O8 from boundary grade uranium ore based on stirring leaching is shown in the following figure. After the boundary grade uranium ore is crushed and ground, the concentrated ore slurry is stirred and leached. The leached ore slurry is subjected to multi-stage countercurrent decantation. The overflow containing a small amount of fine mud is adsorbed by a slurry ion exchange device. The uranium-loaded resin is eluted with sulfuric acid. The elution liquid is further enriched with uranium by extraction-strip extraction. The stripping liquid precipitates ammonium diuranate, and the ammonium diuranate is calcined to obtain U3O8. DETAILED DESCRIPTION

[0038] The following specific embodiments are intended to further illustrate the present invention in detail, rather than to limit the scope of protection of the claims of the present invention.

[0039] Example 1

[0040] A certain boundary grade uranium ore, uranium grade 0.029%. Uranium is recovered from it to prepare U3O8, the specific steps are as follows:

[0041] (1) Ore crushing and grinding: Ore crushing and grinding to -2mm mesh (accounting for 80%).

[0042] (2) Stirring leaching: In the above step (1), the ore was stirred and leached, the liquid-to-solid volume mass ratio was 0.3 mL / g, the amount of concentrated sulfuric acid added was 3.5% relative to the mass of the ore, the amount of ferric sulfate added was 1.6% relative to the mass of the ore, the leaching time was 9 h, and the Fe 3+ Concentration 3.5g / L, pH 1.65.

[0043] (3) Ore classification: After leaching in the above step (2), the ore is classified by a slurry vibrating screen with a classification particle size of 60 mesh; the coarse sand is vacuum filtered and four-stage countercurrent washing is performed. The ratio of the washing water volume to the ore mass in each washing stage is 0.5 mL:1 g, and the washing water is the adsorption tail liquid.

[0044] (4) fine mud slurry ion exchange adsorption of uranium: the coarse sand washing water in the above step (3) is mixed with the fine mud slurry, the fine mud slurry is inoculated with Thiobacillus ferrooxidans, and a 6-stage trough slurry ion exchange device is used to adsorb uranium. The resin is 201*7 anion exchange resin, the volume ratio of resin addition to fine mud slurry is 1:200, the single-stage residence time is 15 minutes, and air is used to mix the resin and slurry. After adsorption, the fine mud slurry is pumped to a vibrating screen to separate the resin and slurry; 20g / t (based on the mass of the original ore) of FZ3802 amphoteric flocculant is added to the slurry and transported to a thickener for solid-liquid separation. The underflow is transported to the tailings dam, and the adsorbed tailings are returned to steps (2) and (3) for leaching and coarse sand washing, respectively.

[0045] (5) Elution: The loaded resin obtained after separation by the vibrating screen in the above step (4) is eluted with 10 wt % dilute sulfuric acid to obtain lean resin and eluent.

[0046] (6) Extraction: The eluent in step (5) is subjected to extraction, with an extractant of 7% N235 + 3.5% TBP-sulfonated kerosene solution, an extraction contact time of 3 min, and the extraction is carried out in a 5-stage countercurrent mixer-settler, with a flow ratio of the eluent to the organic phase of 1.5:1, to obtain raffinate water and an organic phase loaded with uranium, sulfuric acid is added to the raffinate water to a mass fraction of 10%, and the raffinate water is returned to step (5) for use as an eluent.

[0047] (7) Stripping: The organic phase loaded with uranium in step (6) is stripped with 170 g / L ammonium sulfate, and stripping is performed in a three-stage countercurrent mixing clarifier. The contact time between the two phases is 5 min, and the flow ratio of the stripping process is 2:1 between the organic phase and the stripping agent. Concentrated ammonia water is added to adjust the pH of the stripping process to 4.3 to obtain a stripping solution and a lean organic phase. The lean organic phase is returned to (6) to extract uranium.

[0048] (8) Precipitation: The stripping solution obtained in step (7) is passed through ammonia gas to precipitate ammonium diuranate, and the end point pH is 7.3. The ammonium diuranate is filtered and washed to obtain ammonium diuranate and precipitation mother liquor. The mother liquor is returned to step (6) and ammonium sulfate is added before stripping.

[0049] (9) Calcination: In step (8), the ammonium diuranate is calcined at 800° C. for 3 h to obtain a U3O8 product. The ammonia generated during the calcination process is returned to (8) and used as a precipitant.

[0050] The boundary grade uranium ore is extracted with the above steps, and the uranium recovery rate is 81%, and the power consumption is 17kwh / t ore, which is significantly reduced compared with the conventional stirring leaching power consumption of 40-50kwh, and the U3O8 hydrometallurgy cost is 294,000 yuan / t. This process effectively reduces the energy consumption and cost of the ore processing process. In comparison, without using the treatment method in the above embodiment, the stirring leaching ore is crushed to less than 0.5mm, and stirring leaching is carried out under the same conditions. After the leached ore pulp is concentrated, the overflow is adsorbed and recovered by a fluidized bed tower ion exchange device. The remaining steps are the same as the above embodiment, the uranium recovery rate is 76.3%, the power consumption is 28kwh / t ore, and the U3O8 hydrometallurgy cost is 380,000 yuan / t.

[0051] Example 2

[0052] A certain boundary grade uranium ore, uranium grade 0.026%. Uranium is recovered from it to prepare U3O8, the specific steps are as follows:

[0053] (1) Ore crushing and grinding: Ore crushing and grinding to -1mm mesh (accounting for 80%).

[0054] (2) Stirring leaching: The ore in step (1) was stirred and leached, the liquid-to-solid volume mass ratio was 0.3 mL / g, the amount of concentrated sulfuric acid added was 2.55% of the ore mass, the amount of ferric sulfate added was 1.7% of the ore mass, the leaching time was 9 h, and the leaching process Fe 3+ Concentration 2.9g / L, pH 1.80.

[0055] (3) Ore classification: After leaching in the above step (2), the ore is classified by a slurry vibrating screen with a classification particle size of 60 mesh; the coarse sand is vacuum filtered and five-stage countercurrent washing is performed, and the ratio of the washing water volume to the ore mass in each washing stage is 0.5 mL:1 g, and the washing water is the adsorption tail liquid.

[0056] (4) Fine mud slurry ion exchange adsorption of uranium: the coarse sand washing water in the above step (3) is mixed with the fine mud slurry, the fine mud slurry is inoculated with Thiobacillus ferrooxidans, and a 6-stage trough slurry ion exchange device is used to adsorb uranium. The resin is 201*7 anion exchange resin, the volume ratio of resin addition to fine mud slurry is 1:240, the single-stage residence time is 30 minutes, and air is used to mix the resin and slurry. After adsorption, the fine mud slurry is pumped to a vibrating screen to separate the resin and slurry; 45g / t (based on the mass of the original ore) of CZ5005 cationic flocculant is added to the slurry and transported to a thickener for solid-liquid separation. The underflow is transported to the tailings dam, and the adsorbed tailings are returned to steps (2) and (3) for leaching and coarse sand washing, respectively.

[0057] (5) Elution: The loaded resin obtained after separation by the vibrating screen in the above step (4) is eluted with 9 wt % dilute sulfuric acid to obtain lean resin and eluent.

[0058] (6) Extraction: The eluent in step (5) is subjected to extraction, with an extractant of 5% N235 + 2% mixed alcohol-sulfonated kerosene solution, an extraction contact time of 5 min, and the extraction is carried out in a 5-stage countercurrent mixer-settler, with a flow ratio of the eluent to the organic phase of 1.2:1, to obtain raffinate water and an organic phase loaded with uranium, sulfuric acid is added to the raffinate water to a mass fraction of 9%, and the raffinate water is returned to step (5) for use as an eluent.

[0059] (7) Stripping: The organic phase loaded with uranium in step (6) is stripped with 140 g / L ammonium sulfate, and stripping is performed in a 4-stage countercurrent mixing clarifier. The contact time between the two phases is 3 min, and the flow ratio of the stripping process is 3:1 between the organic phase and the stripping agent. Concentrated ammonia water is added to adjust the pH of the stripping process to 4.0 to obtain a stripping solution and a lean organic phase. The lean organic phase is returned to (6) to extract uranium.

[0060] (8) Precipitation: The stripping solution obtained in step (7) is passed through ammonia gas to precipitate ammonium diuranate, and the end point pH is 7.4. The ammonium diuranate is filtered and washed to obtain ammonium diuranate and precipitation mother liquor. The mother liquor is returned to (6) and ammonium sulfate is added before stripping.

[0061] (9) Calcination: In step (8), the ammonium diuranate is calcined at 800° C. for 6 h to obtain a U3O8 product. The ammonia generated during the calcination process is returned to (8) and used as a precipitant.

[0062] The above steps are used to extract U3O8 from the boundary grade uranium ore, with a uranium recovery rate of 81% and a power consumption of 17kwh / t ore, which is significantly lower than the power consumption of conventional stirring leaching of 40 to 50kwh. The U3O8 hydrometallurgical cost is 294,000 yuan / t. This process effectively reduces the energy consumption and cost of the ore processing process.

[0063] The above steps are used to extract U3O8 from the boundary grade uranium ore, with a uranium recovery rate of 83.2%, a power consumption of 17.5kwh / t ore, and a U3O8 hydrometallurgical cost of 315,000 yuan / t. This process effectively reduces the energy consumption and cost of the ore processing process.

[0064] Comparative Example 1

[0065] The same boundary grade uranium ore as in Example 2 was subjected to conventional stirring leaching, the ore was crushed to less than 0.5 mm, and stirring leaching was carried out under the same conditions as in Example 2. The leached slurry was directly filtered by a vacuum bag filter, and the filtrate was adsorbed and recovered uranium by a fluidized bed tower ion exchange device. The resin was easily agglomerated, and the uranium concentration of the tail liquid was 65 mg / L. The remaining steps were the same as in Example 2. The uranium recovery rate was only 74.3%, the power consumption was 42 kwh / t ore, and the U3O8 hydrometallurgical cost was 410,000 yuan / t.

Claims

1. A method for extracting U3O8 from boundary grade uranium ore based on agitation leaching, characterized in that: The following steps are involved: 1) After the boundary grade uranium ore is crushed and ground, it is stirred and leached to obtain a leached slurry; the mass proportion of the boundary grade uranium ore that is crushed and ground to a particle size of -2 mm is not less than 80%; the stirring leaching conditions are: the liquid-to-solid ratio of the slurry is 0.3:1L / kg~0.5:1L / kg, the leaching agents are sulfuric acid and ferric sulfate, and the amount of ferric sulfate added is to control the Fe content in the slurry. 3+ The concentration is 2g / L ~10g / L, the amount of sulfuric acid added is to control the pH of the slurry to be 1~2, the leaching temperature is room temperature, and the leaching time is 30min~30h; 2) Classify the leached slurry to separate the fine mud slurry; 3) After the fine mud slurry is subjected to uranium adsorption by using ion exchange resin, the uranium-loaded resin is screened out; during the uranium adsorption process, Thiobacillus ferrooxidans is inoculated into the fine mud slurry, and air is blown into the fine mud slurry; 4) The uranium-loaded resin is eluted with dilute acid, and the resulting eluent is subjected to extraction and stripping to obtain a uranium-containing solution; 5) Passing ammonia gas into the uranium-containing solution for precipitation to obtain ammonium diuranate precipitate; 6) Calcine the ammonium diuranate precipitate to obtain U3O8; during the calcination process, ammonia gas is generated and recycled to the precipitation process for use.

2. A method for extracting U3O8 from a boundary grade uranium ore based on stirring leaching according to claim 1, characterized in that: The classification particle size is 60 meshes.

3. A method for extracting U3O8 from a boundary grade uranium ore based on stirring leaching according to claim 1 or 2, characterized in that: In the classification process, the coarse sand obtained after separating the fine mud slurry is washed and then transported to the tailings dam; the washing uses water or tailings generated in the uranium adsorption process, and the washing water obtained by washing is combined with the fine mud slurry for treatment.

4. The method for extracting U3O8 from a boundary grade uranium ore based on stirring leaching according to claim 1, characterized in that: In the uranium adsorption process, the deuranium fine mud slurry obtained after screening and separating the loaded resin is subjected to flocculation and thickening treatment, the underflow is transported to the tailings dam, and the overflow is circulated to the stirring leaching or washing process for use.

5. The method for extracting U3O8 from boundary grade uranium ore based on agitation leaching according to claim 1, characterized in that: The dilute acid is dilute sulfuric acid with a concentration in the range of 5wt% to 15wt%.

6. The method for extracting U3O8 from a boundary grade uranium ore based on agitation leaching according to claim 1, characterized in that: The extraction uses an amine extractant; the back-extraction uses an ammonium sulfate solution and an ammonia water back-extraction agent, and the pH of the back-extraction endpoint is controlled to be 4-4.

5.

7. The method for extracting U3O8 from a boundary grade uranium ore based on agitation leaching according to claim 1, characterized in that: During the extraction process, the raffinate produced is circulated to the elution process for use; During the calcination process, ammonia gas is generated and recycled to the precipitation process for use.

Images