A method for processing pyrite fissure type carbonaceous siliceous argillite uranium ore

Abstract

The application belongs to the field of uranium ore processing, and particularly discloses a method for processing pyrite fissure type carbon-silicon mudstone uranium ore, which comprises the following steps: pre-treating the pyrite fissure type carbon-silicon mudstone uranium ore through water immersion to obtain water immersion liquid and water immersion residue; adsorbing uranium in the water immersion liquid by using resin, and performing bacterial oxidation on the adsorption tail liquid and ferrous salt to obtain high-potential bacteria liquid containing ferric iron; mixing the high-potential bacteria liquid containing ferric iron with acid liquid, and then using the mixture for bacterial oxidation leaching of the water immersion residue to obtain acid leaching liquid; and adsorbing uranium in the acid leaching liquid by using resin, and recycling the obtained adsorption tail liquid for bacterial oxidation leaching. The method fills the blank of processing pyrite fissure type carbon-silicon mudstone uranium ore, and has excellent processing effect and efficiency.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, specifically relating to a method for processing pyrite-fractured carbonaceous mudstone uranium ore. Background Technology

[0002] Carbonaceous mudstone uranium deposits are one of the important types of industrial uranium deposits in my country. They are characterized by marine limestone, dolomite, carbonaceous silicate rock, and carbonaceous mudstone as the main ore-bearing rocks, with uranium primarily existing in adsorbed form and coexisting with independent uranium minerals. According to the book "Research and Evaluation of Uranium Deposits in China - Carbonaceous Mudstone Type Uranium Deposits" by uranium geologist Zhao Fengmin, the spatial distribution of carbonaceous mudstone type uranium deposits in my country is very uneven, concentrated in southeastern China, including 22 in Hunan Province, 10 in Guangxi Zhuang Autonomous Region, 7 in Jiangxi Province, 3 in Hubei Province, 4 in Sichuan Province, 2 in Guizhou Province, 2 in Shaanxi Province, 2 in Henan Province, 1 in Guangdong Province, 1 in Gansu Province, and 1 in Inner Mongolia Autonomous Region. Based on their genesis, carbonaceous mudstone uranium deposits in my country are classified into four subcategories and 16 deposit types. Among the carbonaceous mudstone-type deposits that have been explored in my country, the hydrothermal and exogenous infiltration subtypes are the main types, with a few being complex generative subtypes. The industrial uranium deposits now classified as sedimentary-diagenetic type all have obvious superposition of exogenous infiltration mineralization.

[0003] Due to the complex composition of carbonaceous mudstone-type uranium deposits, in addition to siliceous rocks and clay minerals, they are usually rich in organic matter and sulfides (such as pyrite). Some carbonaceous mudstone uranium deposits have high pyrite content (above 5%, and in some cases even above 10%), and uranium and pyrite co-fill small fractures, forming fine veins, thus creating a special type of pyrite-bearing fractured carbonaceous mudstone uranium deposit. No specific reports have been found on processing methods for this type of uranium deposit. If conventional acid stirring leaching is used, on the one hand, this type of uranium deposit generally has low grades, resulting in high production costs and poor efficiency; on the other hand, a high residual acid concentration of over 50 g / L is required to effectively decompose pyrite and achieve a high uranium recovery rate. If conventional column leaching is used, the pyrite is difficult to oxidize and the oxidation process is slow, resulting in a long column leaching cycle and low uranium recovery rate. Summary of the Invention

[0004] To address the challenges in processing complex, low-grade pyrite-fractured carbonaceous mudstone uranium deposits, this invention aims to provide a method for processing pyrite-fractured carbonaceous mudstone uranium deposits, thereby resolving the problems in uranium extraction from these deposits and improving the extraction effect and efficiency of uranium resources.

[0005] Pyrite-bearing fractured carbonaceous mudstone uranium deposits generally have low uranium grades. A portion of the uranium exists in an adsorbed state, while another portion exists as independent minerals such as pitchblende and uraninite, filling small fractures and forming fine veins alongside pyrite. There is no specific treatment method for this type of pyrite-bearing fractured carbonaceous mudstone uranium deposit, and existing conventional leaching processes are insufficient to address the unsatisfactory leaching rates and efficiency caused by the mineral's physicochemical characteristics. To address this problem, this invention, after in-depth research, provides the following improved solution:

[0006] A method for processing pyrite-fractured carbonaceous mudstone uranium ore, comprising the following steps:

[0007] Step (a): Water immersion

[0008] Pyrite-fractured carbonaceous mudstone uranium ore is pre-treated with water to obtain water leaching solution and water leaching residue;

[0009] Step (b): Bacterial-assisted acid leaching

[0010] Uranium in the water leaching solution from step (a) is adsorbed with resin, and the adsorption tail liquid and ferrous salt are subjected to bacterial oxidation to obtain a high-potential bacterial solution containing ferric iron. The high-potential bacterial solution containing ferric iron is then mixed with acid and used for bacterial oxidation leaching of the water leaching residue to obtain an acid leaching solution.

[0011] Step (c): Circulating acid leaching

[0012] Uranium in the acid leaching solution was adsorbed using resin, and the resulting adsorbed solution was recycled for bacterial oxidation leaching.

[0013] To address the problem of unsatisfactory uranium extraction efficiency and effectiveness caused by the physicochemical characteristics of pyrite-fractured carbonaceous mudstone uranium ore, this invention innovatively pre-treats the mineral with water, and uses the water leachate to prepare a high-potential bacterial solution containing trivalent iron for acid leaching. Furthermore, the adsorbed liquid after uranium absorption from the acid leachate is subjected to cyclic acid leaching. The process described in this invention unexpectedly achieves synergistic effects, solving the problems faced in leaching pyrite-fractured carbonaceous mudstone uranium ore and improving uranium extraction efficiency and effectiveness.

[0014] In this invention, the uranium grade in the pyrite-bearing fractured carbonaceous mudstone uranium deposit is 0.05% to 0.15% (more specifically, 0.08% to 0.13%), and the uranium includes adsorbed state, as well as independent minerals such as pitchblende and uranium ore, which together with pyrite fill small fractures and form veinlets.

[0015] In this invention, the uranium content in the pyrite-bearing fractured carbonaceous mudstone uranium deposit can be 30–60 wt.% of the total uranium.

[0016] In this invention, the water leaching method in step (a) is column leaching, which involves: crushing the pyrite fractured carbonaceous mudstone uranium ore to a particle size of -5 to -15 mm and loading it into a column; then spraying it with water for water leaching treatment.

[0017] In this invention, the amount of water used for immersion can be adjusted according to the characteristics of the uranium being treated.

[0018] For example, in the water column immersion stage, the daily water spraying volume per kilogram of mineral is 0.05 to 0.5 L, more preferably 0.1 to 0.2 L, the daily spraying time is 10 to 20 hours, more preferably 12 to 16 hours, and the spraying time is 3 to 7 days, more preferably 4 to 5 days.

[0019] In this invention, the potential of the water immersion stage (which can also be understood as the water immersion liquid) can be -300 to -400 mV, and more specifically, it can be 330 to 400 mV.

[0020] In this invention, the pH of the aqueous extract can be 2 to 4.

[0021] In this invention, in step (b), the resin is at least one of D363B macroporous resin, D201 macroporous resin, 201*7 resin, D263 macroporous resin, and D301 macroporous resin.

[0022] In this invention, the bacteria in the bacterial oxidation stage are at least one of Thiobacillus ferrooxidans, Thiobacillus thiooxidans, and Microspirilla ferrooxidans.

[0023] In this invention, the concentration of ferric iron in the high-potential bacterial solution containing ferric iron is 5-20 g / L, preferably 8-15 g / L.

[0024] In this invention, the potential for bacterial oxidation leaching can be 400–450 mV.

[0025] In this invention, the acid solution is a sulfuric acid solution;

[0026] Preferably, the concentration of sulfuric acid in the solution after mixing the high-potential bacterial solution containing ferric iron and the acid solution is 5-20 g / L, and more preferably 8-15 g / L.

[0027] In this invention, the bacterial-assisted acid leaching method in step (b) is column leaching.

[0028] In this invention, the conditions of column immersion in step (b) can be controlled according to the leaching situation. For example, the daily spraying time is 10 to 20 hours, or more preferably 14 to 18 hours, and the spraying time is 4 to 7 days, preferably 5 to 6 days.

[0029] In this invention, in steps (b) and (c), the resin is at least one of D363B macroporous resin, D201 macroporous resin, 201*7 resin, D263 macroporous resin, and D301 macroporous resin.

[0030] In this invention, the potential for the post-adsorption liquid circulation used in the bacterial oxidation stage can be 400–550 mV.

[0031] Beneficial effects:

[0032] (1) This invention innovatively pre-treats pyrite-fractured carbonaceous mudstone uranium ore with water leaching, and uses the water leaching solution to prepare a high-potential bacterial solution containing trivalent iron for acid leaching treatment. Furthermore, the adsorbed solution after uranium absorption by the acid leaching solution is subjected to cyclic acid leaching treatment. The process described in this invention unexpectedly achieves synergistic effects, solving the problems faced in leaching pyrite-fractured carbonaceous mudstone uranium ore, and improving uranium extraction efficiency and effectiveness.

[0033] (2) This invention is highly practical and can process most pyrite-fractured carbon-silica mudstone uranium ore. It avoids the problems of high production cost and high residual acid required by conventional stirring process. The overall production cost is low, the operation is feasible, and it is easy to industrialize. Attached Figure Description

[0034] Figure 1 This is a process flow diagram of the present invention;

[0035] Figure 2 SEM images of pyrite-bearing fractured carbonaceous mudstone uranium deposits in Example 1 are shown; where (a) is a uranium ore (Coff) encasing pyrite (Py), and (b) is a pitchblende (Pit) filling pyrite (Py) fractures. Detailed Implementation

[0036] In this invention, the pyrite-bearing fractured carbonaceous mudstone uranium deposit has a uranium grade of generally 0.05% to 0.15%. Part of the uranium exists in an adsorbed state, while the other part, along with independent minerals such as pitchblende and uranium ore, fills small fissures and forms fine veins together with pyrite.

[0037] This invention discloses a typical method for processing pyrite-bearing fractured carbonaceous-silica mudstone uranium deposits, comprising the following steps:

[0038] (1) ore column loading: First, the pyrite fractured carbonaceous mudstone uranium ore is crushed to a certain extent and then placed in the column leaching device;

[0039] (2) Water spraying: Use water spraying to leach the adsorbed uranium from the ore after crushing and loading in step (1);

[0040] First, leaching the pyrite-bearing fractured carbonaceous siliceous mudstone uranium ore with water to obtain an aqueous solution (pH = 3-4) will cause a large amount of uranium to be converted into [UO2(SO4)2]. 2- and [UO2(SO4)3] 4- The anionic form of Fe enters the solution and is leached out. However, if an acidic leaching agent is sprayed directly, the Fe dissolved in the sulfuric acid will be leached out. 2+ and S - Under the action of restoring U 6+ For U 4+ This hinders the rapid leaching of uranium and increases the difficulty of subsequent leaching.

[0041] (3) Uranium adsorption: The high-concentration uranium-containing solution obtained in step (2) is used to adsorb uranium using resin ion exchange to obtain the adsorption tail liquid;

[0042] (4) Bacterial oxidation: The adsorbed tail liquid obtained in step (3) is supplemented with ferrous sulfate and then subjected to bacterial oxidation to obtain a high potential bacterial solution containing ferric iron.

[0043] (5) High potential bacterial solution spraying: The high potential bacterial solution obtained by oxidizing bacteria in step (4) is sprayed with sulfuric acid and then sprayed on the ore column after leaching in step (2). The pyrite in the ore is oxidized by the combined action of trivalent iron and bacteria, and the independent uranium minerals coexisting with pyrite are leached.

[0044] (6) Circulating spray: After uranium adsorption is performed on the solution obtained in step (5), the adsorption tail liquid is circulated and sprayed.

[0045] (7) Washing the column with clean water: After the cyclic spraying in step (6) is completed, stop spraying and wait for the solution in the column to flow out naturally. Then wash the column with clean water and finally unload the column to take samples for analysis of the uranium content in the tailings.

[0046] The specific steps (1) are as follows: crushing the pyrite fractured carbonaceous mudstone uranium ore to a particle size of -5 to -15 mm and packing it into a column;

[0047] The specific steps (2) are as follows: spraying the crushed and packed ore with clean water in step (1), with the daily spraying amount of clean water being 5 to 15% of the ore weight, for 3 to 5 days;

[0048] The specific steps (3) are as follows: using macroporous resin to ion exchange adsorb uranium into the high-concentration uranium-containing solution obtained in step (2) to obtain the adsorption tail liquid;

[0049] The specific steps (4) are as follows: after adding ferrous sulfate to the adsorbed tail liquid obtained in step (3), bacterial oxidation is carried out to obtain a high potential bacterial solution containing 8-15 g / L of ferric iron. The bacteria used are ferrous thiobacillus.

[0050] The specific steps (5) are as follows: the high potential bacterial solution obtained by bacterial oxidation in step (4) is supplemented with sulfuric acid to 5-20 g / L and then sprayed onto the ore column after leaching in step (2). The pyrite in the ore is oxidized by the action of trivalent iron and bacteria, and the independent uranium minerals coexisting with pyrite are leached.

[0051] The specific steps (6) are as follows: after uranium adsorption on the solution obtained in step (5), the adsorption tail liquid is circulated and sprayed.

[0052] The specific steps (7) are as follows: after the cyclic spraying in step (6) is completed, stop the spraying and wait for the solution in the column to flow out naturally, then wash the column with clean water, and finally unload the column and take samples to analyze the uranium content in the tailings.

[0053] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited thereto.

[0054] Example 1

[0055] The uranium ore of a certain carbonaceous mudstone is a uranium-bearing pyrite fracture-type ore with a uranium grade of 0.097%. Uranium and pyrite together fill small fractures and form fine veins in the ore. Its chemical composition is shown in Table 1, and the mineral distribution in the ore is shown in Table 2.

[0056] Table 1. Main chemical composition of uranium ore from a fractured carbonaceous mudstone containing pyrite.

[0057]

[0058] Table 2. Mineral composition of uranium ore from a fractured carbonaceous mudstone containing pyrite.

[0059]

[0060]

[0061] The uranium in this uranium ore exists partly in an adsorbed state and partly in the form of uranium minerals. Uranium minerals include uranium ore and pitchblende. Uranium ore is mainly distributed in submicroscopic granular form, often encapsulated by or associated with pyrite. Pitchblende is mainly distributed in microscopic to submicroscopic granular form, often associated with pyrite. Figure 2 .

[0062] The processing steps are as follows:

[0063] (1) Ore loading: First, the pyrite fractured carbonaceous mudstone uranium ore is crushed to -8mm, mixed and reduced, and then 20kg of ore sample is weighed and placed in a column leaching device with a column diameter of 10cm.

[0064] (2) Water spraying: Take 2L of water daily to spray the ore after crushing and loading the column, and leach the adsorbed uranium. The spraying system is 16h spraying and 8h stopping. This stage is sprayed for 5 days to obtain a leachate with a pH value of 2-4 and a uranium concentration of 0.105-2.20g / L.

[0065] (3) Uranium adsorption: The uranium-containing solution obtained in step (2) was subjected to ion exchange adsorption using D363B macroporous resin to obtain the adsorption tail liquid;

[0066] (4) Bacterial oxidation: Ferrous sulfate is added to the adsorbed tail liquid obtained in step (3) to make the total iron content reach 8-10 g / L. The bacterial oxidation device is used to carry out the oxidation culture of ferrous thiobacillus to obtain a high potential bacterial solution containing 8-10 g / L of ferric iron.

[0067] (5) High potential bacterial solution spraying: After adding sulfuric acid to the high potential bacterial solution obtained by bacterial oxidation in step (4) to 8-10 g / L, spray it onto the ore column after leaching in step (2). Use the action of trivalent iron and bacteria to oxidize pyrite in the ore and leach independent uranium minerals that coexist with pyrite. In this stage, the spraying system of 16 hours of spraying and 8 hours of stopping is also adopted, and the spraying lasts for 5 days.

[0068] (6) Circulating spraying: The solution obtained in step (5) is ion exchanged with D363B macroporous resin to adsorb uranium, and the adsorption tail liquid is circulated and sprayed. In this stage, the spraying system of spraying for 16 hours and stopping for 8 hours is also adopted, and the spraying lasts for 25 days.

[0069] (7) Washing the column with clean water: After the cyclic spraying in step (6) is completed, stop spraying and wait for the solution in the column to flow out naturally. Then wash the column with clean water and finally unload the column to take samples for analysis of the uranium content in the tailings.

[0070] Final results: Uranium grade in tailings 0.009%, uranium leaching rate based on tailings 90.72%, acid consumption 3.58%.

[0071] Table 3 shows the leaching statistics for the stages of clear water spraying, bacterial solution spraying, and tail liquid circulation spraying.

[0072] Table 3. Statistical results of leaching at each stage

[0073]

[0074]

[0075] The following table compares the recovery of uranium from Example 1 using various methods of existing technology with that of Example 1:

[0076] Comparative Example 1: Conventional stirring acid leaching

[0077] The crushed ore described in Example 1 was pre-ground to a particle size of -100 mesh, and then placed in a sulfuric acid solution with a concentration of 80-100 g / L, with 3% MnO2 as the oxidant, and stirred at 80°C for 4 hours. The acid consumption was 5.52%, the residual acid in the leachate was 50-60 g / L, and the leaching rate was 90.72%.

[0078] Comparative Example 2 - Conventional Column Immersion

[0079] Compared with Example 1, the difference is that the column was packed according to step 1 of Example 1, and then sprayed with a sulfuric acid solution with 3% MnO2 as oxidant for 60 days (leaching potential is the same as in Example 1, for example -405 to -445 mV), with a leaching rate of 85.57%.

[0080] Comparative Example 3

[0081] Compared with Example 1, the only difference is that the water immersion process in step (2) is missing, as is step 3. In addition, the adsorption tail liquid used in step 4 is replaced by an equal amount of clean water. Other operations and parameters, such as leaching potential, are the same as in Example 1.

[0082] Comparative Example 4

[0083] Compared to Example 1, the only difference is that in step 2, a 20 g / L sulfuric acid solution is used instead of the water. All other operations and parameters are the same as in Example 1.

[0084] The processing results of Example 1 and Comparative Examples 1-4 are shown in Table 4.

[0085] Table 4

[0086]

[0087] In summary, for the difficult-to-process pyrite-fractured carbonaceous mudstone uranium ore, this invention, through ingenious pre-water leaching treatment, uses the tailings of the water leaching adsorbed U for subsequent bacterial leaching. This unexpectedly improves the leaching effect, achieving comparable or even superior leaching results without grinding, with lower acid consumption and shorter time.

[0088] Example 2

[0089] A carbonaceous mudstone uranium deposit in western Hunan, my country, has a uranium grade of 0.085%. Approximately 45% of the uranium in the ore exists in an adsorbed state, while about 55% exists as independent uranium minerals. Uranite and pitchblende, along with pyrite, fill small fissures and form fine veins. The pyrite content is 8.82%. Its chemical composition is shown in Table 5.

[0090] Table 5. Main chemical composition of pyrite-fissurian siliceous mud uranium ore from a fractured pyrite deposit in western Hunan.

[0091]

[0092] The uranium ore was treated with conventional stirred acid leaching (operation similar to Comparative Example 1), with a grinding particle size of -100 mesh, a temperature of 65°C, an acid consumption of 5.88%, and a leaching rate of 88.24%. Alternatively, conventional column leaching (operation similar to Comparative Example 2) was used, with leaching for 55 days at an ore particle size of -10 mm, achieving a leaching rate of 84.71%. The method described in this invention for treating this uranium ore includes the following process steps:

[0093] (1) Ore loading: First, the pyrite fractured carbonaceous mudstone uranium ore is crushed to -5mm, mixed and reduced, and then 5kg of ore sample is weighed and placed in a column leaching device with a column diameter of 5cm.

[0094] (2) Water spraying: Take 0.5L of water daily to spray the ore after crushing and loading the column, and leach the adsorbed uranium. The spraying system is 12h spraying and 12h stopping. This stage is sprayed for 4 days to obtain a leachate with a pH value of 2 to 3.8 and a uranium concentration of 0.10 to 1.85g / L.

[0095] (3) Uranium adsorption: The uranium-containing solution obtained in step (2) was subjected to ion exchange adsorption using D201 macroporous resin to obtain the adsorption tail liquid;

[0096] (4) Bacterial oxidation: Ferrous sulfate is added to the adsorbed tail liquid obtained in step (3) to make the total iron content reach ~8g / L. The bacterial oxidation device is used to carry out the oxidation culture of ferrous thiobacillus to obtain a high potential bacterial solution containing not less than 8g / L of ferric iron.

[0097] (5) High potential bacterial solution spraying: After adding sulfuric acid to the high potential bacterial solution obtained by bacterial oxidation in step (4) to 10-15 g / L, spray it onto the ore column after leaching in step (2). Use the action of trivalent iron and bacteria to oxidize pyrite in the ore and leach independent uranium minerals that coexist with pyrite. This stage also adopts a spraying system of 16 hours of spraying and 8 hours of stopping, and spraying for 6 days.

[0098] (6) Circulating spraying: The solution obtained in step (5) is ion exchanged with D201 macroporous resin to adsorb uranium, and the adsorption tail liquid is circulated and sprayed. In this stage, the spraying system of spraying for 12 hours and stopping for 12 hours is also adopted, and the spraying lasts for 22 days.

[0099] (7) Washing the column with clean water: After the cyclic spraying in step (6) is completed, stop spraying and wait for the solution in the column to flow out naturally. Then wash the column with clean water and finally unload the column to take samples for analysis of the uranium content in the tailings.

[0100] Table 6 shows the leaching statistics for the stages of clear water spraying, bacterial solution spraying, and tail liquid circulation spraying.

[0101] Table 6. Statistical results of leaching at each stage

[0102]

[0103] Final results: Uranium grade in tailings 0.010%, uranium leaching rate based on slag 88.24%, acid consumption 4.25%; compared with conventional stirring, acid consumption was reduced from 5.88% to 4.25%, and no grinding or stirring was required, resulting in low energy consumption; compared with conventional column leaching process, leaching rate based on slag could be increased from 84.71% to 88.24%, and leaching time was reduced from 55 days to 32 days.

[0104] Example 3

[0105] The uranium ore from a carbonaceous mudstone in Guangxi, my country, is a pyrite-fractured uranium ore with a uranium grade of 0.125%. Uranium and pyrite co-fill small fractures and form fine veins in the ore. Its chemical composition is shown in Table 7.

[0106] Table 7. Main chemical composition of uranium ore from a fractured carbonaceous mudstone pyrite-type pyrite-type siliceous mudstone.

[0107]

[0108] In this uranium ore, approximately 35.8% of uranium exists in an adsorbed state, while the remaining 64.2% exists as two independent uranium minerals: uranium ore and pitchblende. Uranium ore and pitchblende, along with pyrite, fill small fissures and form fine veins. Pyrite content is 6.87%, and it is in close association with uranium ore and pitchblende.

[0109] The uranium ore was treated with conventional stirred acid leaching (operation similar to Comparative Example 1) at a grinding particle size of -80 mesh, a temperature of 80°C, an acid consumption of 5.52%, and a leaching rate of 90.40%. Alternatively, conventional column leaching (operation similar to Comparative Example 2) was used for 68 days at an ore particle size of -8 mm, achieving a leaching rate of 88.0%. The method described in this invention for treating this uranium ore comprises the following process steps:

[0110] (1) Ore loading: First, the pyrite fractured carbonaceous mudstone uranium ore is crushed to -6mm, mixed and reduced, and then 20kg of ore sample is weighed and placed in a column leaching device with a column diameter of 10cm.

[0111] (2) Water spraying: Take 2L of water daily to spray the ore after crushing and loading the column, and leach the adsorbed uranium. The spraying system is 16h spraying and 8h stopping. This stage is sprayed for 5 days to obtain a leachate with a pH value of 2-4 and a uranium concentration of 0.139-3.15g / L.

[0112] (3) Uranium adsorption: The uranium-containing solution obtained in step (2) was subjected to ion exchange adsorption using D363B macroporous resin to obtain the adsorption tail liquid;

[0113] (4) Bacterial oxidation: Ferrous sulfate is added to the adsorbed tail liquid obtained in step (3) to make the total iron content reach 9-10 g / L. The bacterial oxidation device is used to carry out the oxidation culture of ferrous thiobacillus to obtain a high potential bacterial solution containing 9-10 g / L of ferric iron.

[0114] (5) High potential bacterial solution spraying: After adding sulfuric acid to the high potential bacterial solution obtained by bacterial oxidation in step (4) to 10-15 g / L, spray it onto the ore column after leaching in step (2). Use the action of trivalent iron and bacteria to oxidize pyrite in the ore and leach independent uranium minerals that coexist with pyrite. This stage also adopts a spraying system of 16 hours of spraying and 8 hours of stopping, and spraying for 6 days.

[0115] (6) Circulating spraying: The solution obtained in step (5) is ion exchanged with D363 macroporous resin to adsorb uranium, and the adsorption tail liquid is circulated and sprayed. In this stage, the spraying system of spraying for 16 hours and stopping for 8 hours is also adopted, and the spraying lasts for 33 days.

[0116] (7) Washing the column with clean water: After the cyclic spraying in step (6) is completed, stop spraying and wait for the solution in the column to flow out naturally. Then wash the column with clean water and finally unload the column to take samples for analysis of the uranium content in the tailings.

[0117] Table 8 shows the leaching statistics for the stages of clear water spraying, bacterial solution spraying, and tail liquid circulation spraying.

[0118] Table 8. Statistical results of leaching at each stage

[0119]

[0120] Final results: uranium grade in tailings 0.011%, uranium leaching rate based on slag 91.20%, acid consumption 4.78%; compared with conventional stirring, acid consumption was reduced from 5.52% to 4.78%, and no grinding or stirring was required, resulting in low energy consumption; compared with conventional column leaching process, leaching rate based on slag could be increased from 88.0% to 91.20%, and leaching time was reduced from 68 days to 44 days.

[0121] In summary, this method, based on the form of uranium in this type of uranium ore and the oxidation state of pyrite, is precisely divided into three stages for uranium extraction: The first stage uses the oxidized pyrite in the fractures to produce acid, followed by leaching of the uranium ore with water without reagents, allowing most of the adsorbed uranium to be leached first; the second stage utilizes the combined action of high ferric iron and bacterial oxidation to accelerate the oxidation of pyrite, thereby leaching the uranium associated with it. This stage also involves the implantation of bacteria into the ore pile; the third stage uses circulating spraying of the adsorption tailings to gradually enable bacteria to self-reproduce within the ore column, continuing to utilize the oxidation effect of bacteria and ferric iron to further decompose the pyrite and leach the remaining uranium. This invention is highly practical, capable of processing most pyrite-fractured carbonaceous mudstone uranium ore, eliminating the need for fine ore grinding, avoiding the problem of high residual acid in agitated acid leaching, and has low overall production costs. It is feasible to operate and easy for industrial production.

Claims

1. A method for processing pyrite-fractured carbonaceous mudstone uranium ore, characterized by the following steps: include: Step (a): Water immersion Pyrite-fractured carbonaceous mudstone uranium ore is pre-treated with water to obtain water leaching solution and water leaching residue; In the pyrite-fractured carbonaceous mudstone uranium deposit, the uranium grade is between 0.05% and 0.15%, and the uranium includes adsorbed state, as well as independent minerals such as pitchblende and uranium ore, which together with pyrite fill small fractures and form fine veins. In the pyrite-fractured carbonaceous mudstone uranium deposits, the uranium content existing as an independent mineral accounts for 30-60 wt.% of the total uranium. The water leaching method in step (a) is column leaching, which involves: crushing the pyrite-fractured carbonaceous mudstone uranium ore and loading it into a column; then spraying it with water for water leaching treatment. During the water column leaching stage, the daily water spraying volume per kilogram of mineral is 0.05~0.5L, the daily spraying time is 10~20h, and the spraying time is 3~7 days; Step (b): Bacterial-assisted acid leaching Uranium in the water leaching solution from step (a) is adsorbed with resin, and the adsorption tail liquid and ferrous salt are subjected to bacterial oxidation to obtain a high-potential bacterial solution containing ferric iron. The high-potential bacterial solution containing ferric iron is then mixed with acid and used for bacterial oxidation leaching of the water leaching residue to obtain an acid leaching solution. The bacteria in the bacterial oxidation phase are at least one of the following: ferrooxidizing thiobacillus, thiosulfate-oxidizing thiobacillus, and ferrooxidizing microspirilla. Step (c): Circulating acid leaching Uranium in the acid leaching solution was adsorbed using resin, and the resulting adsorbed solution was recycled for bacterial oxidation leaching.

2. The method for processing pyrite-fractured carbonaceous mudstone uranium ore as described in claim 1, characterized in that, In the column leaching of step (a), the pyrite fractured carbonaceous mudstone uranium ore is crushed to a particle size of 5-15 mm.

3. The method for processing pyrite-fractured carbonaceous mudstone uranium ore as described in claim 1, characterized in that, During the water column leaching stage, the daily water spraying volume per kilogram of mineral is 0.1~0.2L, and the daily spraying time is 12~16h; the spraying time is 4~5 days.

4. The method for processing pyrite-fractured carbonaceous mudstone uranium ore as described in claim 1, characterized in that, In high-potential bacterial solutions containing ferric iron, the concentration of ferric iron is 5~20 g / L.

5. The method for processing pyrite-fractured carbonaceous mudstone uranium ore as described in claim 4, characterized in that, In high-potential bacterial solutions containing ferric iron, the concentration of ferric iron is 8-15 g / L.

6. The method for processing pyrite-fractured carbonaceous mudstone uranium ore as described in claim 1, characterized in that, The acid solution is a sulfuric acid solution.

7. The method for processing pyrite-fractured carbonaceous mudstone uranium ore as described in claim 1, characterized in that, The concentration of sulfuric acid in the solution obtained by mixing high-potential bacterial solution containing ferric iron with acid solution is 5~20 g / L.

8. The method for processing pyrite-fractured carbonaceous mudstone uranium ore as described in claim 1, characterized in that, The bacterial-assisted acid leaching method in step (b) is column leaching.

9. The method for processing pyrite-fractured carbonaceous mudstone uranium ore as described in any one of claims 1 to 8, characterized in that, In steps (b) and (c), the resin is at least one of D363B macroporous resin, D201 macroporous resin, 201×7 resin, D263 macroporous resin, and D301 macroporous resin.

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