Oxidation leaching system and method for argillaceous sandstone uranium ore

Abstract

The invention discloses an oxidation leaching system and method for argillaceous sandstone uranium ore. The system comprises a uranium leaching pool, a recovery pool, a liquid preparation-dosing unit pool and an intermediate pool. Wherein the uranium leaching tank is provided with a water dispersing layer, a uranium ore layer and a liquid collecting layer from top to bottom, and efficient oxidation of uranium ore is achieved through coupling of oxygen and ferric iron; the recovery pool is sequentially provided with a resin adsorption layer and a water inlet layer from top to bottom, and efficient recovery of uranium in the leachate is achieved; the liquid preparation-dosing unit pool is provided with an acid-resistant submersible sewage pump used for circularly conveying the ore leaching liquid to the uranium leaching pool and adjusting the pH value of the ore leaching liquid and the initial concentration of Fe < 3 + >. And the middle tank drives the ore leaching liquid to form periodic tidal flow circulation in the uranium leaching tank through an acid-resistant submersible sewage pump. According to the system and the method, tidal flow regulation and control, aeration oxygen supply enhancement and iron ion circulation oxidation technologies are coupled, and the uranium leaching rate gt of the argillaceous sandstone uranium ore is achieved by establishing a multi-stage oxidation field domain, optimizing a fluid migration path and establishing an iron element regeneration mechanism; 92%.

Description

Technical Field

[0001] The present invention belongs to the technical field of in-situ leaching of uranium, and particularly relates to an oxidation leaching system and method for argillaceous sandstone uranium ore. Background Art

[0002] Uranium is a key resource for nuclear energy development and is widely used in nuclear power, national defense, and high-tech fields. However, with the increasing depletion of high-grade uranium ore resources, the development and utilization of low-grade uranium ore have become a key issue to be solved urgently. Argillaceous sandstone uranium ore exhibits typical "three lows and one high" characteristics (low permeability, low porosity, low grade, and high clay content) and has always been regarded as a "dormant ore" that is difficult to mine. Its efficient development and utilization are difficult problems in the industry.

[0003] In-situ leaching of uranium is widely used in sandstone uranium ore with better permeability due to its lower cost and smaller environmental impact. However, its application in argillaceous sandstone uranium ore is fundamentally restricted: in low-permeability ore bodies, problems such as difficult effective supply of oxygen, low utilization efficiency of oxidants, and difficult optimization of redox reaction conditions directly lead to low leaching efficiency of uranium. In addition, traditional acid leaching processes also have problems such as long leaching time, high reagent consumption, and high environmental risks when treating argillaceous sandstone uranium ore, which have all become technical bottlenecks in the development of argillaceous sandstone uranium ore.

[0004] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] The object of the present invention is to provide an oxidation leaching system and method for argillaceous sandstone uranium ore to solve problems such as difficult effective supply of oxygen and low utilization efficiency of oxidants in traditional processes. The system and method couple tidal flow regulation, enhanced aeration oxygen supply, and iron ion cyclic oxidation technologies. By establishing a multi-stage oxidation field, optimizing the fluid migration path, and establishing an iron element regeneration mechanism, the uranium leaching rate of argillaceous sandstone uranium ore is > 92%, which has significant technical economy.

[0006] To achieve the above object, the present invention provides an oxidation leaching system for argillaceous sandstone uranium ore, which comprises: a uranium leaching pool, which comprises a water-spraying layer, a uranium ore layer, and a liquid-collecting layer arranged in layers from top to bottom; a plurality of perforated water pipes are arranged in the water-spraying layer, and the perforated water pipes are horizontally laid on the uranium ore layer for introducing leaching solution into the uranium leaching pool, and the leaching solution is an acidic soluble ferric salt; the uranium ore layer contains uranium ore particles to be leached, and the particle size of the uranium ore particles is 0.3 - 3.0 mm; the liquid-collecting layer is filled with a high-permeability material with a particle size of 7 - 20 mm, and the permeability coefficient of the high-permeability material is 1×10 -2Above cm / s, a liquid collecting pipe is arranged in the liquid collecting layer, liquid collecting holes are formed in the liquid collecting pipe, and the liquid collecting pipe is connected with an aeration device for collecting leachate and aerating the uranium leaching pool; a recovery pool, which is sequentially provided with a resin adsorption layer and a water inlet layer from top to bottom, its liquid inlet is arranged at the water inlet layer, and its liquid outlet is arranged above the resin adsorption layer; the resin adsorption layer is filled with strongly basic anion exchange resin for adsorbing and recovering the leached uranium; the liquid inlet at the water inlet layer is connected with the liquid collecting pipe through a liquid inlet pipe, and a solenoid valve I is arranged between the liquid inlet pipe and the liquid collecting pipe; a liquid preparation-drug adding unit pool, which is communicated with the liquid outlet of the recovery pool and the water spraying layer of the uranium leaching pool, is filled with leaching solution, and is equipped with an acid-resistant submersible pump I, and the liquid preparation-drug adding unit pool is used for circulating and transporting the leaching solution to the uranium leaching pool and adjusting the pH and initial Fe 3+ concentration of the leaching solution; an intermediate pool, which is communicated with the liquid collecting layer of the uranium leaching pool and is provided with a solenoid valve II for collecting and controlling the liquid discharged from the uranium leaching pool, and an acid-resistant submersible pump II is configured therein, and the acid-resistant submersible pump II circulates and backfeeds the leaching solution to the water spraying layer of the uranium leaching pool through an intermediate pool outlet pipe; and a time controller, which is linked with the solenoid valve I and the solenoid valve II to realize periodic flooding-drainage.

[0007] Preferably, the thickness of the uranium ore layer is 1-6 m; and / or, the perforation aperture of the perforated water distribution pipe is 3-8 mm, and the perforation distribution density is 10-30 pieces / m; and / or, the liquid collecting holes of the liquid collecting pipe have an aperture of 5-10 mm, and the number of the openings is 20-40 pieces / m.

[0008] Preferably, the high-permeability material is selected as gravel with a permeability coefficient of 1×10 -2 ~1×10 0 cm / s.

[0009] Preferably, the aeration device is a Roots blower or a high-pressure blower, and the installation position of the Roots blower or the high-pressure blower is higher than the top of the uranium ore layer.

[0010] Preferably, the strongly basic anion exchange resin is selected from D201 resin, and the resin regeneration period is 3-5 leaching cycles; and / or, the filling height of the resin adsorption layer is 60-80% of the effective height of the recovery pool.

[0011] Preferably, the liquid preparation-drug adding unit pool includes: a liquid preparation pool and a drug adding pool; wherein, the liquid preparation pool is filled with leaching solution, which is communicated with the recovery pool through a recovery pool outlet pipe, and an acid-resistant submersible pump I is configured therein, and the acid-resistant submersible pump I is communicated with the uranium leaching pool through a liquid preparation pool outlet pipe for circulating and transporting the leaching solution to the uranium leaching pool; the drug adding pool is internally provided with a medicament for adjusting the pH and initial Fe 3+The concentration, the chemical addition tank is connected to the liquid preparation tank through a chemical addition tank outlet pipe, and a corrosion-resistant metering pump is provided on the connected pipeline.

[0012] Another object of the present invention is to provide a method for oxidizing and leaching argillaceous sandstone uranium ore, which uses the above-mentioned argillaceous sandstone uranium ore oxidation leaching system. The method includes: (S1) Introduce the ore leaching solution into the uranium leaching tank, and evenly distribute the ore leaching solution through the water spraying layer to completely immerse the uranium ore layer, and control the initial pH of the ore leaching solution to be 2.0-2.5; (S2) Leaching stage: During the flooding period, intermittently supply oxygen through the aeration device to the liquid collecting pipe and the liquid collecting layer to make the dissolved oxygen 5.0-8.0 mg / L. The aeration intermittent period is 20-40% of the flooding duration. At the same time, regulate the pH value of the ore leaching solution between 2.0 and 2.5 to promote the Fe 3+ / O2 synergistic oxidation of uranium ore to oxidize tetravalent uranium to hexavalent uranium and form uranyl sulfate ions; after the reaction reaches the set time, open the second solenoid valve to discharge the uranium-containing ore leaching solution into the intermediate tank; During the drying period, introduce fresh air into the liquid collecting pipe and the liquid collecting layer to continue to synergistically oxidize uranium with the residual Fe in the uranium ore + After a certain drying time, input the ore leaching solution in the intermediate tank into the uranium leaching tank, and operate in a cyclic tidal flow mode until the concentration of hexavalent uranium in the ore leaching solution ≥ 1.5 g / L; (S3) Solid iron stage: After adjusting the pH of the ore leaching solution to 3.0, open the first solenoid valve, and Fe 3+ Remain in the uranium leaching tank in the form of precipitation, and discharge the liquid in the uranium leaching tank into the recovery tank; (S4) Adsorption stage: In the recovery tank, use strongly basic anion exchange resin to adsorb and recover uranium in the ore leaching solution, and then introduce the tail liquid into the liquid preparation - chemical addition unit tank; (S5) Liquid preparation stage: In the liquid preparation - chemical addition unit tank, adjust the pH value of the ore leaching solution to make the pH 2.0-2.5, and then transport the ore leaching solution to the uranium leaching tank through the acid-resistant submersible pump 1 to start a new round of leaching cycle.

[0013] Preferably, in step (S1), the ore leaching solution is selected from acidic ferric sulfate solution, and the initial value of the Fe 3+ concentration of the acidic ferric sulfate solution is 5.5 x , unit: g / L, x is the numerical value of the uranium content in the argillaceous sandstone uranium ore in g / kg.

[0014] Preferably, in step (S2), in the tidal flow operation mode, perform periodic flooding-drainage operations 2 to 4 times a day, with a single flooding duration of 4 to 8 hours, to achieve the tidal flow circulation of the leaching solution; or / and, in step (S2), during the drying period, introduce fresh air into the liquid collecting pipe and the liquid collecting layer to continue to synergistically oxidize uranium with the remaining Fe in the uranium ore 3+ for 2 to 4 hours, and then input the leaching solution in the intermediate pond into the uranium leaching pond to cycle the tidal flow operation mode.

[0015] Preferably, in step (S2), during the drying period, adjust the oxygen content in the pores of the uranium ore layer to not less than 10% by intermittent aeration for oxygen supply.

[0016] The argillaceous sandstone uranium ore oxidation leaching system and method of the present invention have the following advantages: 1. Tidal flow-ferro-oxygen dynamic coupling oxygen supply mechanism The system and method of the present invention break through the boundary of traditional oxygen supply technology. Through the flooding-drainage cycle and aeration of the uranium leaching pond and the intermediate pond, a "non-steady-state infiltration-gas-liquid two-phase oxidation" coupling system is constructed to achieve the synergistic improvement of the oxidant transport efficiency and reaction kinetics: (1) Through the temporal coupling of tidal flow dry-wet alternation and intermittent aeration (DO 5-8 mg / L) during flooding, compared with the traditional mechanical continuous aeration process, the oxygen supply energy consumption per unit ore is reduced by 60% - 80%; (2) Establish an Fe 3+ / O2 coupling oxidation regeneration system, and achieve in-situ efficient regeneration of Fe 3+ (regeneration rate > 92%) under the conditions of pH 2.0 - 2.5, and the iron salt consumption is reduced by 60% - 80%.

[0017] 2. Stepwise pH regulation and multistage coordination mechanism Construct a three-stage dynamic regulation system of "leaching-solid iron-adsorption" to achieve the optimal matching of key process parameters: (1) Strengthened control in the leaching stage (pH 2.0 - 2.5): The sulfuric acid consumption is reduced by about 25% (compared with the traditional acid leaching process with pH 1.5 - 2.0); (2) Precise regulation in the solid iron stage (pH 3.0): When the pH is 3, the ferric ions in the solution will hydrolyze to form ferric hydroxide precipitation, and more than 90% of the Fe 3+ is retained in the uranium leaching pond in the form of precipitation, effectively preventing the poisoning of the adsorption performance of D201 resin by Fe 3+ , and at the same time, this pH fits the best adsorption window of the resin, and the uranium adsorption rate > 98%; (3) Closed-loop circulation system: More than 90% of the precipitated Fe(III) can be reversely dissolved in the next round of leaching (pH 2.0 - 2.5), ensuring the efficient cyclic activation of the iron oxidant, thereby increasing the overall uranium leaching rate to more than 92%.

[0018] 3. Environmentally friendly and sustainable reaction system The present invention constructs a sustainable reaction system of "iron oxidant regeneration - acidity balance - nearly zero liquid waste discharge", and this system achieves a conversion rate of more than 92% of Fe 2+ to Fe 3+ . Through the hydrolysis of Fe 3+ to produce H + , it partially compensates for the total acid consumption of the system and helps to self-stably regulate the pH value of the system; in addition, the leachate after uranium adsorption and recovery by D201 resin is fully recycled to the liquid preparation tank, effectively promoting the recycling of resources. Description of the drawings

[0019] Figure 1 is a schematic structural diagram of the oxidized leaching system for argillaceous sandstone uranium ore of the present invention.

[0020] In the figure: 1 - uranium leaching tank; 2 - recovery tank; 3 - liquid preparation tank; 4 - chemical addition tank; 5 - intermediate tank; 10 - Roots blower or high-pressure blower; 11 - ventilation pipe; 12 - liquid collection layer; 13 - uranium ore layer; 14 - water dispersion layer; 15 - liquid collection pipe; 16 - solenoid valve 1; 17 - solenoid valve 2; 20 - inlet pipe; 21 - water inlet layer; 22 - resin adsorption layer; 23 - recovery tank outlet pipe; 30 - acid-resistant submersible pump 1; 50 - acid-resistant submersible pump 2; 31 - leaching solution; 32 - liquid preparation tank outlet pipe; 40 - chemical agent; 41 - chemical addition tank outlet pipe; 42 - corrosion-resistant metering pump; 51 - intermediate tank outlet pipe. Specific embodiments

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] It should be noted that in the present invention, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0023] The features mentioned in the present invention can be combined arbitrarily as long as there is no contradiction in the combination of these features. All possible combinations should be considered as the scope described in this specification. Each feature disclosed in the specification can be replaced by any alternative feature that can provide the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are only general examples of equivalent or similar features.

[0024] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. The terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In addition, unless otherwise clearly specified and defined, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] There are many problems in traditional uranium extraction technologies. For example, it is difficult to effectively supply oxygen in low-permeability ore bodies, the utilization efficiency of oxidants is low, the leaching time of traditional acid leaching is long, the reagent consumption is high, and the environmental risk is large. These have all become technical bottlenecks in the development of argillaceous sandstone uranium ore. The inventors of the present invention applied the tidal flow process to uranium extraction. Although the tidal flow process realizes pore reoxygenation through wet-dry alternation in the field of sewage treatment, there are significant technical gaps in directly transplanting it to the uranium ore leaching scenario: First, the swelling rate of clay minerals such as montmorillonite in argillaceous sandstone can reach 18% - 25% when encountering water. This swelling phenomenon will cause the cumulative decrease of the ore layer permeability by 40% - 60% during repeated wet-dry cycles. In addition, during the flooding period of the traditional tidal process, the dissolved oxygen will rapidly decrease, weakening the oxidation effect of oxygen and affecting the effectiveness of the process.

[0026] Based on the above analysis, to achieve the efficient development of argillaceous sandstone uranium ore, the following technical shackles need to be broken through: (1) Construct a multi-phase transmission enhancement system for oxidation media to overcome the mass transfer limitation of low-permeability ore bodies; (2) Establish a precise regulation mechanism for redox conditions to achieve the dynamic balance of the Fe 3+ / O2 synergistic oxidation system; (3) Design a leaching-recovery closed-loop process to reduce reagent consumption and environmental pollution risks. It should be particularly pointed out that in this technology, the following core contradictions need to be effectively solved: the rate matching problem between the periodic infiltration characteristics of the tidal flow process and the slow kinetics of the uranium oxidation reaction, and the oxidant regeneration efficiency problem of the iron-oxygen cycle system in heterogeneous porous media.

[0027] The system and method of the present invention break through the boundaries of traditional oxygen supply technology. Through the flooding-drainage cycle and aeration of the uranium leaching pool and the intermediate pool, a "non-steady infiltration-gas-liquid two-phase oxidation" coupling system is constructed to achieve the synergistic improvement of the oxidant transport efficiency and reaction kinetics: (1) Through the sequential coupling of tidal flow wet-dry alternation and intermittent aeration during flooding (DO 5-8 mg / L), compared with the traditional mechanical continuous aeration process, the oxygen supply energy consumption per unit of ore is reduced by 60% - 80%; (2) An Fe 3+ / O2 coupled oxidation regeneration system is established to achieve the in-situ efficient regeneration of Fe 3+ (regeneration rate > 92%) under the condition of pH 2.0 - 2.5, and the iron salt consumption is reduced by 60% - 80%.

[0028] Based on this, the present invention provides a muddy sandstone uranium ore oxidation leaching system. Referring to Figure 1 Figure, this system includes: a uranium leaching pool 1, a recovery pool 2, a liquid preparation-drug addition unit pool, an intermediate pool 5, and a time controller. Among them, the uranium leaching pool 1 is connected to both the recovery pool 2 and the intermediate pool 5, and the tidal flow cycle of the leaching solution 31 is realized through the circulation between the uranium leaching pool 1 and the intermediate pool 5. The recovery pool 2 is used to adsorb the leached uranium. The liquid preparation-drug addition unit pool is connected to the recovery pool 2 for recovering the tail liquid after adsorption and the preparation of the leaching solution 31. The liquid preparation-drug addition unit pool is connected to the uranium leaching pool 1 for transporting the leaching solution 31 to the uranium leaching pool 1. The leaching solution 31 is an acidic soluble ferric salt, such as acidic ferric sulfate. The time controller is used to control the tidal flow cycle.

[0029] The above-mentioned uranium leaching pool 1 includes a water-dispersing layer 14, a uranium ore layer 13, and a liquid-collecting layer 12 arranged in layers from top to bottom. The water-dispersing layer 14 is provided with a number of perforated water-dispersing pipes, which are horizontally laid on the uranium ore layer 13 for introducing the leaching solution 31 into the uranium leaching pool 1. The uranium ore layer 13 contains uranium ore particles to be leached, and the particle size of the uranium ore particles is 0.3 - 3.0 mm. The liquid-collecting layer 12 is filled with a highly permeable material with a particle size of 7 - 20 mm, and the permeability coefficient of the highly permeable material is above 1×10 -2 cm / s. A liquid-collecting pipe 15 is arranged in the liquid-collecting layer 12. The liquid-collecting pipe 15 is provided with liquid-collecting holes, and the liquid-collecting pipe 15 is connected with an aeration device for collecting the leaching solution and aerating the inside of the uranium leaching pool 1.

[0030] The above-mentioned recovery pool 2 is sequentially provided with a resin adsorption layer 22 and a water inlet layer 21 from top to bottom. Its liquid inlet is arranged at the water inlet layer 21, and its liquid outlet is arranged above the resin adsorption layer 22. The resin adsorption layer 22 is filled with strongly basic anion exchange resin for adsorbing and recovering the leached uranium. The liquid inlet at the water inlet layer 21 is connected to the liquid-collecting pipe 15 through a liquid inlet pipe 20, and a solenoid valve 16 is arranged between the liquid inlet pipe 20 and the liquid-collecting pipe 15.

[0031] The above-mentioned liquid preparation - dosing unit pool is connected to both the liquid outlet of the recovery pool 2 and the water - spreading layer 14 of the uranium leaching pool 1. It is filled with leaching solution 31 and equipped with an acid - resistant submersible pump 30. The liquid preparation - dosing unit pool is used to circulate the leaching solution 31 to the uranium leaching pool 1 and adjust the pH and initial Fe 3+ concentration.

[0032] The above - mentioned intermediate pool 5 is connected to the liquid collection layer 12 of the uranium leaching pool 1 and is equipped with a solenoid valve 17, which is used to collect and control the liquid discharged from the uranium leaching pool 1. An acid - resistant submersible pump 50 is configured inside it. The acid - resistant submersible pump 50 circulates the leaching solution 31 back to the water - spreading layer 14 of the uranium leaching pool 1 through the intermediate pool outlet pipe 51.

[0033] The above - mentioned time controller is linked with the solenoid valve 16 and the solenoid valve 17 to achieve periodic flooding - drainage.

[0034] Furthermore, the thickness of the uranium ore layer 13 is 1 - 6 m.

[0035] Furthermore, the perforation aperture of the perforated water - distribution pipe is 3 - 8 mm, and the perforation distribution density is 10 - 30 pieces / m, ensuring that the non - uniformity of the distribution of the leaching solution 31 is <5%.

[0036] Furthermore, the high - permeability material is selected as gravel with a permeability coefficient of 1×10 -2 ~1×10 0 cm / s. The permeability coefficient of the gravel is much higher than that of clay (1×10 -7 cm / s) and dense sand (1×10 -3 cm / s), meeting the high - permeability material standard.

[0037] Furthermore, the liquid - collecting holes of the liquid - collecting pipe 15 have an aperture of 5 - 10 mm, and the number of openings is 20 - 40 pieces / m.

[0038] Furthermore, the aeration device is a Roots blower or a high - pressure blower 10. The installation position of the Roots blower or the high - pressure blower 10 is higher than the top of the uranium ore layer 13. One end of the liquid - collecting pipe 15 in the liquid - collecting layer 12 is connected to the Roots blower or the high - pressure blower 10 through a ventilation pipe 11, which can aerate and adjust the oxygen content. The installation position of the Roots blower or the high - pressure blower 10 is higher than the top of the uranium ore layer 13 to prevent the leaching solution 31 from flowing into the Roots blower or the high - pressure blower 10.

[0039] Furthermore, the strongly basic anion - exchange resin is selected from D201 resin, and the resin regeneration period is 3 - 5 leaching cycles.

[0040] Furthermore, the filling height of the resin adsorption layer 22 is 60 - 80% of the effective height of the recovery pool 2.

[0041] Furthermore, the liquid preparation - medicine adding unit pool includes: a liquid preparation pool 3 and a medicine adding pool 4. Among them, the liquid preparation pool 3 is filled with leaching solution 31, which is connected to the recovery pool 2 through the recovery pool effluent pipe 23. A corrosion - resistant submersible pump 30 is equipped inside it. The corrosion - resistant submersible pump 30 is connected to the uranium leaching pool 1 through the liquid preparation pool water outlet pipe 32, and is used to circulate and transport the leaching solution 31 to the uranium leaching pool 1. The medicine adding pool 4 contains medicine 40, and the medicine 40 is used to adjust the pH of the leaching solution and the initial concentration of Fe 3+ concentration. The medicine adding pool 4 is connected to the liquid preparation pool 3 through the medicine adding pool water outlet pipe 41, and a corrosion - resistant metering pump 42 is provided on the connected pipeline.

[0042] Another object of the present invention is to provide a method for oxidative leaching of argillaceous sandstone uranium ore. This method uses an oxidative leaching system for argillaceous sandstone uranium ore, and this method includes: (S1) Introduce the leaching solution 31 (i.e., acidic ferric sulfate solution) into the uranium leaching pool 1, and evenly distribute the leaching solution 31 through the water - spreading layer 14 to completely immerse the uranium ore layer 13, and control the initial pH of the leaching solution 31 to be 2.0 - 2.5; (S2) Leaching stage: During the flooding period, intermittently supply oxygen by aeration to the liquid collection pipe 15 and the liquid collection layer 12 through the aeration device, so that the dissolved oxygen is 5.0 - 8.0 mg / L, and the aeration intermittent cycle is 20 - 40% of the flooding duration. At the same time, regulate the pH value of the leaching solution 31 between 2.0 - 2.5 to promote the Fe 3+ / O2 synergistic oxidation of uranium ore to oxidize tetravalent uranium to hexavalent uranium and form uranyl sulfate ions; after the reaction reaches the set time (i.e., the duration of the flooding period), open the solenoid valve 17 to drain the uranium - containing leaching solution into the intermediate pool 5; During the drying period, introduce fresh air into the liquid collection pipe 15 and the liquid collection layer 12 to continue the synergistic oxidation of uranium with the residual Fe in the uranium ore 3+ After a certain drying time, input the leaching solution in the intermediate pool 5 into the uranium leaching pool 1, and operate in a cyclic tidal flow mode until the concentration of hexavalent uranium in the leaching solution 31 ≥ 1.5 g / L; (S3) Iron - solidifying stage: After adjusting the pH of the leaching solution to 3.0, open the solenoid valve 16, and Fe 3+ is retained in the uranium leaching pool 1 in the form of precipitation, and the liquid in the uranium leaching pool 1 is drained into the recovery pool 2; (S4) Adsorption stage: In the recovery pool 2, use strongly basic anion exchange resin to adsorb and recover uranium in the leaching solution 31, and then introduce the tail liquid into the liquid preparation - medicine adding unit pool; (S5) Liquid preparation stage: In the liquid preparation - dosing unit pool, adjust the pH value of the leaching solution 31 to 2.0 - 2.5, and then transport the leaching solution 31 to the uranium leaching pool 1 through the acid - resistant submersible pump 30 to start a new round of leaching cycle.

[0043] Further, in step (S1), the leaching solution 31 is an acidic ferric sulfate solution, and the initial concentration of Fe 3+ in this acidic ferric sulfate solution is 5.5 x , with the unit of g / L; x is the numerical value of the uranium content in the argillaceous sandstone uranium ore in g / kg.

[0044] Further, in step (S2), in the tidal flow operation mode, perform the periodic flooding - drainage operation 2 - 4 times a day, with the single - time flooding duration of 4 - 8 hours to achieve the tidal flow circulation of the leaching solution 31.

[0045] Further, in step (S2), during the drying period, introduce fresh air into the collecting pipe 15 and the collecting layer 12, and adjust through intermittent aeration to ensure that the oxygen content in the pores of the uranium ore is not less than 10%, and act jointly with the remaining Fe 3+ in the uranium ore to carry out the co - oxidation of uranium for 2 - 4 hours continuously.

[0046] The following uses Examples 1 - 2 to elaborate in detail on a system and method for oxidative leaching of argillaceous sandstone uranium ore provided by the present invention.

[0047] Example 1 A system for oxidative leaching of argillaceous sandstone uranium ore has the structure as described above, which will not be elaborated here. Among them, the length × width × height of the uranium leaching pool 1 is 1×1×1.5 m, the thickness of the uranium ore layer 13 is 1 m, the particle size of the uranium ore is 0.5 - 0.8 mm (containing approximately 360 g of uranium in total), the perforation diameter of the perforated water - distributing pipe is 5 mm, and the perforation distribution density of the perforated water - distributing pipe is 20 pieces / m. The thickness of the collecting layer 12 is 15 cm, filled with gravel with a particle size of 10 - 15 mm. The D201 resin is filled in the resin adsorption layer 22, with a filling volume of 100 L and an adsorption flow rate of 1.0 BV / h. The concentration of Fe 3+ in the leaching solution 31 is 0.99 g / L (calculated according to 5.5 x , x = 0.18 g / kg), and the pH is 2.3 ± 0.1. Set the flooding cycle to 3 times a day, with the single - time flooding duration of 6 hours (including the drainage time), and the drying duration of 2 hours (including the water - inlet time); use a high - pressure blower for aeration, and aerate for 10 minutes every 30 minutes during the flooding period.

[0048] Use the above - mentioned system to leach the argillaceous sandstone uranium ore sample (average grade 0.018%) from a certain argillaceous sandstone uranium mine in Inner Mongolia, and the operation steps are as follows: (1) Leaching stage: Inject the prepared acidic ferric sulfate leaching solution into the uranium leaching pool 1, and form a tidal flow operation mode through the turnover of the intermediate pool 5. During the flooding period, aerate to maintain the dissolved oxygen at 5.5 - 6.5 mg / L. During this period, adjust the pH of the leaching solution to be maintained at about 2.3, and sample and detect the uranium concentration in each tidal flow cycle. (2) When the U(VI) concentration of the leaching solution reaches 1.5 g / L, adjust the pH to 3.0 and then discharge it into the recovery pool 2, and use D201 resin to adsorb and recover uranium. (3) The tail liquid after uranium recovery enters the liquid preparation pool 3, adjust the pH to about 2.3, and then pump it into the uranium leaching pool 1. (4) Repeat the above operations. After the system runs for 20 days, a total of 345 g of uranium is extracted, and the uranium leaching rate is 95.83%. At the same time, when the pH is about 2.3, the Fe 3+ concentration in the leaching solution still remains at about 0.90 g / L, indicating that the efficient regeneration and recycling of Fe 3+ are realized.

[0049] Example 2 A system for oxidative leaching of argillaceous sandstone uranium ore, the structure of which is as described above and will not be elaborated. Among them, the length × width × height of the uranium leaching pool 1 is 1.5 × 1.5 × 1.5 m, the thickness of the uranium ore layer 13 is 1 m, the particle size of the uranium ore is 0.4 - 0.6 mm (containing about 620 g of uranium in total), the perforation aperture of the perforated water distribution pipe is 8 mm, and the perforation distribution density of the perforated water distribution pipe is 12 pieces / m. The thickness of the liquid collection layer 12 is 15 cm, and the crushed stones with a particle size of 8 - 12 mm are filled. The D201 resin is filled in the resin adsorption layer 22, and the filling amount is 150 L, and the adsorption flow rate is 0.8 BV / h. The Fe 3+ concentration in the leaching solution 31 is 1.70 g / L (calculated according to 5.5 x , x = 0.31 g / kg), and the pH is 2.1 ± 0.1. Set the flooding cycle to 4 times / day, the single flooding duration is 4 hours (including the drainage time), and the drying duration is 2 hours (including the water inlet time); use a high-pressure blower for aeration, and aerate for 12 minutes every 30 minutes during the flooding period.

[0050] Use the above system to leach the argillaceous sandstone uranium ore sample (average grade 0.031%) from a certain argillaceous sandstone uranium ore in Xinjiang. The operation steps are as follows: (1) Leaching stage: Inject the prepared ferric sulfate leaching solution into the uranium leaching pool 1, and form a tidal flow operation mode through the turnover of the intermediate pool 5. During the flooding period, aerate to maintain the dissolved oxygen at 6.0 - 7.0 mg / L. During this period, adjust the pH of the leaching solution to be maintained at about 2.1, and sample and detect the uranium concentration in each tidal flow cycle. (2) When the concentration of U(VI) in the leaching solution reaches 1.5 g / L, adjust the pH to 3.0 and then discharge it into the recovery pool 2, and use D201 resin to adsorb and recover uranium; (3) The tail liquid after uranium recovery enters the liquid preparation pool 3, adjust the pH to about 2.1, and then pump it into the uranium leaching pool 1; (4) Cycle the above operations. After the system runs for 15 days, a total of 580 g of uranium is extracted, and the uranium leaching rate is 93.55%; at the same time, when the pH is about 2.1, Fe in the leaching solution 3+ The concentration still remains at about 1.55 g / L, indicating that the efficient regeneration and recycling of Fe 3+ are realized.

[0051] Although the content of the present invention has been introduced in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation to the present invention. After those skilled in the art read the above content, various modifications and substitutions to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A leaching system for oxidized argillaceous sandstone uranium ore, characterized in that, The system includes: Leaching uranium pool (1), which includes a water spraying layer (14), a uranium ore layer (13) and a liquid collecting layer (12) arranged in layers from top to bottom; several perforated water pipes are arranged in the water spraying layer (14), and the perforated water pipes are horizontally laid on the uranium ore layer (13) for introducing leaching solution (31) into the leaching uranium pool (1), and the leaching solution (31) is an acidic trivalent soluble iron salt; the uranium ore layer (13) contains uranium ore particles to be leached, and the particle size of the uranium ore particles is 0.3~3.0 mm; the liquid collecting layer (12) is filled with a highly permeable material with a particle size of 7~20 mm, and the permeability coefficient of the highly permeable material is above 1×10 -2 cm / s. A liquid collecting pipe (15) is arranged in the liquid collecting layer (12), liquid collecting holes are opened on the liquid collecting pipe (15), and the liquid collecting pipe (15) is connected with an aeration device for collecting leaching solution and aerating the leaching uranium pool (1); A recovery pool (2) which is successively provided with a resin adsorption layer (22) and a water inlet layer (21) from top to bottom. Its liquid inlet is arranged at the water inlet layer (21), and its liquid outlet is arranged above the resin adsorption layer (22). The resin adsorption layer (22) is filled with strongly basic anion exchange resin for adsorbing and recovering the leached uranium. The liquid inlet at the water inlet layer (21) is connected to the liquid collecting pipe (15) through a liquid inlet pipe (20), and an electromagnetic valve I (16) is arranged between the liquid inlet pipe (20) and the liquid collecting pipe (15). The liquid preparation - dosing unit tank is connected to both the liquid outlet of the recovery tank (2) and the water - spreading layer (14) of the uranium leaching tank (1). It is filled with leaching solution (31) and is equipped with an acid - resistant submersible pump I (30). The liquid preparation - dosing unit tank is used to circulate the leaching solution to the uranium leaching tank (1) and adjust the pH and the initial Fe 3+ concentration; An intermediate pool (5) which is communicated with the liquid collecting layer (12) of the uranium leaching pool (1) and is provided with an electromagnetic valve II (17) for collecting and controlling the liquid discharged from the uranium leaching pool (1). A acid-resistant submersible pump II (50) is configured therein. The acid-resistant submersible pump II (50) circulates and backfeeds the leaching solution to the water spraying layer (14) of the uranium leaching pool (1) through an intermediate pool outlet pipe (51); and A time controller which is linked with the electromagnetic valve I (16) and the electromagnetic valve II (17) to realize periodic flooding - draining.

2. The oxidized leaching system for argillaceous sandstone uranium ore according to claim 1, wherein The thickness of the uranium ore layer (13) is 1 - 6 m; Or / and, the perforation aperture of the perforated water distribution pipe is 3 - 8 mm, and the perforation distribution density is 10 - 30 pieces / m; Or / and, the liquid collecting holes of the liquid collecting pipe (15) have an aperture of 5 - 10 mm and the number of openings is 20 - 40 pieces / m.

3. The oxidized leaching system for argillaceous sandstone uranium ore according to claim 1, characterized in that, The selected highly permeable material is gravel with a permeability coefficient of 1×10 -2 ~1×10 0 cm / s.

4. The oxidized leaching system for argillaceous sandstone uranium ore according to claim 1, characterized in that, The aeration device is a Roots blower or a high-pressure blower (10), and the installation position of the Roots blower or the high-pressure blower is higher than the top of the uranium ore layer (13).

5. The oxidized leaching system for argillaceous sandstone uranium ore according to claim 1, wherein The strongly basic anion exchange resin is selected from D201 resin, and the resin regeneration period is 3 - 5 leaching cycles; Or / and, the filling height of the resin adsorption layer (22) is 60 - 80% of the effective height of the recovery pool (2).

6. The oxidized leaching system for argillaceous sandstone uranium ore according to claim 1, characterized in that The liquid preparation - chemical addition unit pool includes: a liquid preparation pool (3) and a chemical addition pool (4); Among them, the liquid preparation pool (3) is filled with a leaching solution (31), which is communicated with the recovery pool (2) through a recovery pool outlet pipe (23). An acid-resistant submersible pump I (30) is equipped therein. The acid-resistant submersible pump I (30) is communicated with the uranium leaching pool (1) through a liquid preparation pool outlet pipe (32) for circularly transporting the leaching solution to the uranium leaching pool (1); The dosing tank (4) contains a chemical agent (40) which is used to adjust the pH of the leaching solution and the initial concentration of Fe 3+ The dosing tank (4) is connected to the solution preparation tank (3) through a dosing tank outlet pipe (41), and a corrosion-resistant metering pump (42) is provided on the connected pipeline.

7. A method for oxidative leaching of argillaceous sandstone uranium ore, characterized in that, This method uses the argillaceous sandstone uranium ore oxidation leaching system as described in any one of claims 1 - 6. This method includes: (S1) Introduce the leaching solution (31) into the uranium leaching pool (1), and evenly distribute the leaching solution through the water spraying layer (14) to completely immerse the uranium ore layer (13), and control the initial pH of the leaching solution to be 2.0 - 2.5; (S2) Leaching stage: During the flooding period, the collecting pipe (15) and the collecting layer (12) are intermittently aerated and supplied with oxygen through the aeration device, so that the dissolved oxygen is 5.0 - 8.0 mg / L, and the aeration intermittent cycle is 20 - 40% of the flooding duration. At the same time, the pH value of the leaching solution is regulated between 2.0 and 2.5 to promote the Fe 3+ / O2 synergy oxidizes tetravalent uranium to hexavalent uranium and forms uranyl sulfate ions; after the reaction reaches the set time, the solenoid valve two (17) is opened to discharge the uranium-containing leaching solution into the intermediate pool (5); During the water drainage period, fresh air is introduced into the liquid collecting pipe (15) and the liquid collecting layer (12) to synergistically oxidize uranium remaining in the uranium ore with Fe 3+ After draining water for a certain period of time, the leaching solution in the intermediate pond (5) is input into the uranium leaching pond (1), and the circulating tidal flow operation mode is adopted until the concentration of hexavalent uranium in the leaching solution ≥ 1.5 g / L; (S3) Iron fixation stage: After adjusting the pH of the leaching solution to 3.0, turn on the first electromagnetic valve (16), and Fe 3+ is retained in the uranium leaching tank (1) in the form of precipitation, and the liquid in the uranium leaching tank (1) is discharged into the recovery tank (2); (S4) Adsorption stage: In the recovery pool (2), use strongly basic anion exchange resin to adsorb and recover the uranium in the leaching solution, and then introduce the tail liquid into the liquid preparation - chemical addition unit pool; (S5) Liquid preparation stage: In the liquid preparation - chemical addition unit pool, adjust the pH value of the leaching solution to be 2.0 - 2.5, and then transport the leaching solution to the uranium leaching pool (1) through the acid-resistant submersible pump I (30) to start a new round of leaching cycle.

8. The method for oxidative leaching of argillaceous sandstone uranium ore according to claim 7, characterized in that, In step (S1), the leaching solution (31) is selected from acidic ferric sulfate solution, and the initial concentration of the acidic ferric sulfate solution is Fe 3+ with an initial value of 5.5 x , unit: g / L, x being the numerical value of uranium content in argillaceous sandstone uranium ore in g / kg.

9. The method for oxidative leaching of argillaceous sandstone uranium ore according to claim 7, characterized in that, In step (S2), in the tidal flow operation mode, a periodic flooding-drainage operation is performed 2 to 4 times a day, and the single flooding duration is 4 to 8 hours, so as to realize the tidal flow circulation of the leaching solution. Or / and, in step (S2), during the draining process, fresh air is introduced into the liquid collecting pipe (15) and the liquid collecting layer (12) to co-oxidize the residual Fe in the uranium ore 3+ Continue to co-oxidize uranium for 2 to 4 hours, and then input the leaching solution in the intermediate pond into the uranium leaching pond to operate in a circulating tidal flow mode.

10. The method for oxidative leaching of argillaceous sandstone uranium ore according to claim 7, characterized in that, In step (S2), during the drying period, the oxygen content in the pores of the uranium ore layer (13) is adjusted to be not less than 10% by intermittent aeration for oxygen supply.

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