A system and method for oxidative leaching of argillaceous sandstone uranium ore

Abstract

The present invention discloses a system and method for oxidative leaching of argillaceous sandstone uranium ore. The system includes: a uranium leaching pool, a recovery pool, a liquid preparation - chemical addition unit pool, and an intermediate pool. Among them, the uranium leaching pool is hierarchically provided with a water - spreading layer, a uranium ore layer, and a liquid - collecting layer from top to bottom, and high - efficient oxidation of uranium ore is achieved by coupling oxygen with ferric iron. The recovery pool is sequentially provided with a resin adsorption layer and a water - inlet layer from top to bottom to achieve high - efficient recovery of uranium in the leaching solution. The liquid preparation - chemical addition unit pool is equipped with an acid - resistant submersible sewage pump, which is used to circulate the ore - leaching solution to the uranium leaching pool and adjust the pH and the initial concentration of Fe 3+ in the ore - leaching solution. The intermediate pool drives the ore - leaching solution to form a periodic tidal flow circulation in the uranium leaching pool through an acid - resistant submersible sewage pump. The system and method of the present invention couple tidal flow regulation, aeration oxygen supply enhancement, and iron ion cyclic oxidation technologies. By establishing a multi - level 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%.

Description

Technical Field

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

[0002] Uranium is a key resource for the development of nuclear energy and is widely used in nuclear power, defense, and high-tech sectors. However, with the dwindling availability of high-grade uranium ore, the development and utilization of low-grade uranium ores has become a critical issue that demands urgent attention. Argillaceous sandstone uranium deposits exhibit the typical characteristics of "three lows and one high" (low permeability, low porosity, low grade, and high argillaceous content), making them difficult to mine and a "dead end" ore. Their efficient development and utilization remains a major challenge for the industry.

[0003] In-situ leaching of uranium is widely used in highly permeable sandstone uranium deposits due to its low cost and minimal environmental impact. However, its application in argillaceous sandstone uranium deposits is fundamentally limited: in the low-permeability ore bodies, oxygen is difficult to effectively supply, oxidant utilization is inefficient, and redox reaction conditions are difficult to optimize, resulting in low uranium leaching efficiency. Furthermore, traditional acid leaching processes for argillaceous sandstone uranium deposits suffer from long leaching times, high reagent consumption, and significant environmental risks, all of which constitute technical bottlenecks in the development of argillaceous sandstone uranium deposits.

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

[0005] The present invention aims to provide a system and method for oxidative leaching of argillaceous sandstone uranium ore to address problems such as the difficulty in effectively supplying oxygen and low oxidant utilization efficiency in traditional processes. This system and method, coupled with tidal flow regulation, enhanced aeration and oxygen supply, and iron ion circulation oxidation technology, establish a multi-stage oxidation field, optimize fluid migration paths, and establish an iron regeneration mechanism. The system and method achieve a uranium leaching rate of >92% for argillaceous sandstone uranium ore, demonstrating significant technical and economic benefits.

[0006] In order to achieve the above-mentioned object, the present invention provides an oxidation leaching system for muddy sandstone uranium ore, which comprises: a uranium leaching tank, which comprises a water dispersion layer, a uranium ore layer and a liquid collection layer arranged in layers from top to bottom; the water dispersion layer is provided with a plurality of perforated water dispersion pipes, which are horizontally laid on the uranium ore layer and are used to pass leaching liquid into the uranium leaching tank, wherein the leaching liquid is an acidic soluble trivalent iron 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 collection 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 within 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 - medicine adding unit pool, which is communicated with the liquid outlet of the recovery pool and the water spreading layer of the uranium leaching pool, contains leaching solution, and is equipped with an acid - resistant submersible pump I, and the liquid preparation - medicine adding unit pool is used for circularly transporting the leaching solution to the uranium leaching pool and adjusting the pH and the initial Fe 3+ concentration; 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 is configured with an acid - resistant submersible pump II therein, and the acid - resistant submersible pump II circularly back - transports the leaching solution to the water spreading 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 - distributing 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 - medicine adding unit pool comprises: a liquid preparation pool and a medicine adding pool; wherein, the liquid preparation pool contains leaching solution, is communicated with the recovery pool through a recovery pool outlet pipe, is equipped with an acid - resistant submersible pump I therein, and the acid - resistant submersible pump I is communicated with the uranium leaching pool through a liquid preparation pool outlet pipe for circularly transporting the leaching solution to the uranium leaching pool; the medicine adding pool is internally provided with medicaments for adjusting the pH of the leaching solution and the 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 oxidative leaching of argillaceous sandstone uranium ore. This method uses the oxidative leaching system of argillaceous sandstone uranium ore, and this method includes:

[0013] (S1) Introduce the leaching solution into the uranium leaching tank, and evenly distribute the leaching solution through the water-dispersing layer so that the uranium ore layer is completely immersed, and control the initial pH of the leaching solution to be 2.0 - 2.5;

[0014] (S2) Leaching stage:

[0015] During the flooding period, intermittently supply oxygen through the aeration device to the liquid collection pipe and the liquid collection layer, so that the dissolved oxygen is 5.0 - 8.0 mg / L, and the aeration intermittent period is 20 - 40% of the flooding duration. At the same time, regulate the pH value of the leaching solution between 2.0 - 2.5 to promote the Fe 3+ / O2 co-oxidizes uranium ore to oxidize tetravalent uranium to hexavalent uranium and forms uranyl sulfate ions; after the reaction reaches the set time, open the second solenoid valve to discharge the uranium-containing leaching solution into the intermediate tank;

[0016] During the drying period, introduce fresh air into the liquid collection pipe and the liquid collection layer to continue co-oxidizing uranium with the residual Fe in the uranium ore + After a certain drying time, input the 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 leaching solution ≥ 1.5 g / L;

[0017] (S3) Iron fixation stage:

[0018] After adjusting the pH of the leaching solution to 3.0, open the first solenoid valve, and Fe 3+ Remains in the uranium leaching tank in the form of precipitation, and discharges the liquid in the uranium leaching tank into the recovery tank;

[0019] (S4) Adsorption stage:

[0020] In the recovery tank, use strongly basic anion exchange resin to adsorb and recover uranium in the leaching solution, and then introduce the tail liquid into the liquid preparation - chemical addition unit tank;

[0021] (S5) Liquid preparation stage:

[0022] In the liquid preparation - chemical addition unit tank, adjust the pH value of the leaching solution to make the pH 2.0 - 2.5, and then transport the leaching solution to the uranium leaching tank through the acid-resistant submersible pump 1 to start a new round of leaching cycle.

[0023] Preferably, in step (S1), the leaching solution is selected from acidic ferric sulfate solution, and the initial concentration of Fe in the acidic ferric sulfate solution 3+ is 5.5 x , unit: g / L, x and is the uranium content value in argillaceous sandstone uranium ore in g / kg.

[0024] Preferably, in step (S2), in the tidal flow operation mode, perform periodic flooding-drainage operations 2 - 4 times a day, with a single flooding duration of 4 - 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 collecting pipe and the collecting layer to continue to synergistically oxidize uranium with the remaining Fe in the uranium ore 3+ for 2 - 4 hours, and then input the leaching solution in the intermediate pool into the uranium leaching pool to cycle the tidal flow operation mode.

[0025] 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.

[0026] The argillaceous sandstone uranium ore oxidation leaching system and method of the present invention have the following advantages:

[0027] 1. Tidal flow - iron - oxygen dynamic coupling oxygen supply mechanism

[0028] 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 pool and the intermediate pool, a "non - steady - state infiltration - gas - liquid two - phase oxidation" coupling system is constructed to achieve the synergistic improvement of oxidant transport efficiency and reaction kinetics: (1) Through the sequential coupling of tidal flow wet - dry 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 coupled oxidation regeneration system, and achieve in - situ efficient regeneration of Fe 3+ under the conditions of pH 2.0 - 2.5 (regeneration rate > 92%), and the iron salt consumption is reduced by 60% - 80%.

[0029] 2. Staged pH regulation and multistage coordination mechanism

[0030] Construct a three - stage dynamic regulation system of "leaching - solid iron - adsorption" to achieve the optimal matching of key process parameters:

[0031] (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);

[0032] (2)Precise regulation during the iron fixation stage (pH 3.0): When the pH is 3, 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 pool in the form of precipitation, effectively preventing Fe 3+ from poisoning the adsorption performance of D201 resin. At the same time, this pH fits well with the optimal adsorption window of the resin, and the uranium adsorption rate > 98%;

[0033] (3)Closed-loop circulation system: More than 90% of the precipitated Fe(III) can be reversibly 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%.

[0034] 3. Environmentally friendly and sustainable reaction system

[0035] The present invention constructs a sustainable reaction system of "iron oxidant regeneration - acidity balance - near-zero liquid waste discharge". This system achieves a conversion rate of more than 92% of Fe 2+ to Fe 3+ . The hydrolysis of Fe 3+ produces H + to partially compensate for the total acid consumption of the system, which helps to self-stably regulate the pH value of the system. In addition, the leaching solution after uranium adsorption and recovery by D201 resin is fully recycled to the liquid preparation pool, effectively promoting the recycling of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram of the oxidized leaching system for argillaceous sandstone uranium ore of the present invention.

[0037] In the figure: 1 - uranium leaching pool; 2 - recovery pool; 3 - liquid preparation pool; 4 - chemical addition pool; 5 - intermediate pool; 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 - liquid inlet pipe; 21 - water inlet layer; 22 - resin adsorption layer; 23 - recovery pool outlet pipe; 30 - acid-resistant submersible pump 1; 50 - acid-resistant submersible pump 2; 31 - leaching solution; 32 - liquid preparation pool outlet pipe; 40 - chemical agent; 41 - chemical addition pool outlet pipe; 42 - corrosion-resistant metering pump; 51 - intermediate pool outlet pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] 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 the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] 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 brevity and convenience. Accordingly, the description of a numerical range or percentage range should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0040] The features mentioned in the present invention can be combined arbitrarily as long as there is no contradiction in the combination of these features, and all possible combinations should be considered as being within 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 specifically stated, the disclosed features are only general examples of equivalent or similar features.

[0041] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and 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 thus cannot be construed as a limitation on 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 limited, the terms "installed", "connected", "connected to" 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.

[0042] There are many problems in traditional uranium mining technologies, such as the difficulty in effectively supplying oxygen in low-permeability ore bodies, low utilization efficiency of oxidants, long leaching time in traditional acid leaching, high reagent consumption, and high environmental risks. These have all become technical bottlenecks in the development of argillaceous sandstone uranium ore. The inventor of the present invention applied the tidal flow process to uranium mining. Although the tidal flow process realizes pore reoxygenation through wet-dry alternation in the field of sewage treatment, there is a significant technical gap in directly transplanting it to the uranium ore leaching scenario: First, the water swelling rate of clay minerals such as montmorillonite in argillaceous sandstone can reach 18% - 25%, and 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.

[0043] Based on the above analysis, to achieve the efficient development of argillaceous sandstone uranium ore, the following technical bottlenecks need to be overcome: (1) constructing a multi-phase transport enhancement system for oxidation media to overcome the mass transfer limitation of low-permeability ore bodies; (2) establishing a precise regulation mechanism for redox conditions to achieve the dynamic balance of the Fe 3+ / O2 synergistic oxidation system; (3) designing a leaching-recovery closed-loop process to reduce reagent consumption and environmental pollution risks. It should be particularly noted that the following core contradictions need to be effectively solved in this technology: the rate matching problem between the periodic infiltration characteristics of the tidal flow process and the slow kinetics of uranium oxidation reaction, and the oxidant regeneration efficiency problem of the ferrite cycle system in heterogeneous porous media.

[0044] The system and method of the present invention break through the boundaries of traditional oxygen supply technologies. 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 coordinated improvement of oxidant transport efficiency and reaction kinetics: (1) through the sequential coupling of tidal flow wet-dry 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 decreases by 60%~80%; (2) establishing a Fe 3+ / O2 coupled oxidation regeneration system to achieve the in-situ efficient regeneration of Fe 3+ (regeneration rate > 92%) under the condition of pH 2.0~2.5, and the consumption of iron salts decreases by 60%~80%.

[0045] Based on this, the present invention provides an oxidation leaching system for argillaceous sandstone uranium ore. Referring to Figure 1 , 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 a tidal flow cycle of the leaching solution 31 is realized through the cycle 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 and is used to recycle 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 and is used to transport 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.

[0046] 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, and the perforated water-dispersing pipes 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 1×10 -2Above cm / s, a liquid collecting pipe 15 is arranged in the liquid collecting layer 12. Liquid collecting holes are formed in the liquid collecting pipe 15. The liquid collecting pipe 15 is connected with an aeration device for collecting leachate and aerating the uranium leaching pool 1.

[0047] The above-mentioned recovery pool 2 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 with 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.

[0048] The above-mentioned liquid preparation - medicine adding unit pool is communicated with the liquid outlet of the recovery pool 2 and the water spraying layer 14 of the uranium leaching pool 1. It is filled with leaching solution 31 and is equipped with an acid - resistant submersible pump 30. The liquid preparation - medicine adding unit pool is used for circulating and transporting the leaching solution 31 to the uranium leaching pool 1 and adjusting the pH and initial Fe 3+ concentration.

[0049] The above-mentioned intermediate pool 5 is communicated with the liquid collecting layer 12 of the uranium leaching pool 1 and is provided with a solenoid valve 17 for collecting and controlling the liquid discharged from the uranium leaching pool 1. An acid - resistant submersible pump 50 is configured therein. The acid - resistant submersible pump 50 circulates and back - transports the leaching solution 31 to the water spraying layer 14 of the uranium leaching pool 1 through an intermediate pool outlet pipe 51.

[0050] The above - mentioned time controller is linked with the solenoid valve 16 and the solenoid valve 17 to realize periodic flooding - drainage.

[0051] Further, the thickness of the uranium ore layer 13 is 1 - 6 m.

[0052] Further, the perforation aperture of the perforated water - distributing 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%.

[0053] Further, 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 sandy soil (1×10 -3 cm / s), meeting the high - permeability material standard.

[0054] Further, the liquid collecting holes of the liquid collecting pipe 15 have an aperture of 5 - 10 mm, and the number of the openings is 20 - 40 pieces / m.

[0055] Further, 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 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 the ventilation pipe 11, and the oxygen content can be adjusted by aeration. 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.

[0056] Further, the strongly basic anion exchange resin is selected from D201 resin, and the resin regeneration period is 3 to 5 leaching cycles.

[0057] Further, the filling height of the resin adsorption layer 22 is 60% to 80% of the effective height of the recovery pool 2.

[0058] Further, 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 the leaching solution 31, which is communicated with the recovery pool 2 through the recovery pool outlet pipe 23, and is equipped with an acid-resistant submersible pump 30 therein. The acid-resistant submersible pump 30 is connected to the uranium leaching pool 1 through the liquid preparation pool outlet pipe 32 for circulating and transporting the leaching solution 31 to the uranium leaching pool 1. The chemical addition pool 4 contains the chemical agent 40, and the chemical agent 40 is used to adjust the pH of the leaching solution and the initial concentration of Fe 3+ concentration. The chemical addition pool 4 is communicated with the liquid preparation pool 3 through the chemical addition pool outlet pipe 41, and a corrosion-resistant metering pump 42 is provided on the communicating pipe.

[0059] 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:

[0060] (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 distribution 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;

[0061] (S2) Leaching stage:

[0062] During the flooding period, intermittently supply oxygen by aeration to the liquid collecting pipe 15 and the liquid collecting layer 12 through the aeration device, so that the dissolved oxygen is 5.0 - 8.0 mg / L, and the aeration intermittent period is 20% - 40% of the flooding duration. At the same time, regulate the pH value of the leaching solution 31 to be 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 (i.e., the duration of the flooding period), open the solenoid valve 17 to discharge the uranium-containing leaching solution into the intermediate pool 5;

[0063] During the drying period, introduce fresh air into the liquid collecting pipe 15 and the liquid collecting layer 12, and react with the residual Fe in the uranium ore 3+Continue to co-oxidize uranium. After 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 31 is ≥ 1.5 g / L;

[0064] (S3) Solid iron stage:

[0065] After adjusting the pH of the leaching solution to 3.0, solenoid valve 16 is opened, and Fe 3+ is retained in the uranium leaching pond 1 in the form of precipitation, and the liquid in the uranium leaching pond 1 is discharged into the recovery pond 2;

[0066] (S4) Adsorption stage:

[0067] In the recovery pond 2, strong basic anion exchange resin is used to adsorb and recover uranium in the leaching solution 31, and then the tail liquid is introduced into the liquid preparation - chemical addition unit pond;

[0068] (S5) Liquid preparation stage:

[0069] In the liquid preparation - chemical addition unit pond, the pH value of the leaching solution 31 is adjusted to make the pH 2.0 - 2.5. Subsequently, the leaching solution 31 is transported to the uranium leaching pond 1 through acid - resistant submersible pump 1 30, and a new round of leaching cycle is started.

[0070] 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 value of uranium content in argillaceous sandstone uranium ore in g / kg.

[0071] Further, in step (S2), in the tidal flow operation mode, periodic flooding - drainage operations are performed 2 - 4 times a day, and the single - time flooding duration is 4 - 8 hours to achieve the tidal flow cycle of the leaching solution 31.

[0072] Further, in step (S2), during the drying period, fresh air is introduced into the collecting pipe 15 and the collecting layer 12, and the oxygen content in the pores of the uranium ore is ensured to be not less than 10% through intermittent aeration for oxygen supply regulation, and it acts together with the remaining Fe 3+ in the uranium ore to carry out co - oxidation of uranium for 2 - 4 hours continuously.

[0073] The following provides a detailed description of an argillaceous sandstone uranium ore oxidation leaching system and method provided by the present invention through Examples 1 - 2.

[0074] Example 1

[0075] A clayey sandstone uranium ore oxidation leaching system, whose structure is as described above and will not be elaborated here. 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 aperture of the perforated water distribution pipe is 5 mm, and the perforation distribution density of the perforated water distribution pipe is 20 per meter. The thickness of the liquid collection 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. In the leaching solution 31, the Fe 3+ concentration is 0.99 g / L (calculated as 5.5 x , x = 0.18 g / kg), and the pH is 2.3 ± 0.1. The flooding cycle is set to 3 times per day, with a single flooding duration of 6 hours (including the drainage time), and a drying duration of 2 hours (including the water inlet time); high-pressure blower aeration is adopted, and aeration is carried out for 10 minutes every 30 minutes during the flooding period.

[0076] The above system is used to leach a clayey sandstone uranium ore sample (average grade 0.018%) from a certain clayey sandstone uranium ore in Inner Mongolia. The operation steps are as follows:

[0077] (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 intermediate pool 5. During the flooding period, aeration is carried out 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;

[0078] (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;

[0079] (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;

[0080] (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+ have been achieved.

[0081] Example 2

[0082] A leaching system for argillaceous sandstone uranium ore, the structure of which is as described above and will not be elaborated here. 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 (with a total uranium content of about 620 g), 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 per meter. The thickness of the liquid collection layer 12 is 15 cm, and gravel with a particle size of 8 - 12 mm is filled. The D201 resin is filled in the resin adsorption layer 22, with a filling volume of 150 L and an adsorption flow rate of 0.8 BV / h. In the leaching solution 31, the Fe 3+ concentration is 1.70 g / L (calculated as 5.5 x , x = 0.31 g / kg), and the pH is 2.1 ± 0.1. The flooding cycle is set to 4 times per day, the single flooding duration is 4 hours (including the drainage time), and the drying duration is 2 hours (including the water inlet time); high-pressure blower aeration is adopted, and aeration is carried out for 12 minutes every 30 minutes during the flooding period.

[0083] The above system is used to leach the argillaceous sandstone uranium ore sample (average grade 0.031%) collected from a certain argillaceous sandstone uranium ore in Xinjiang. The operation steps are as follows:

[0084] (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 intermediate pool 5. During the flooding period, aeration is carried out 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;

[0085] (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;

[0086] (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;

[0087] (4) Repeat 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, the Fe 3+ concentration in the leaching solution still remains at about 1.55 g / L, indicating that the efficient regeneration and recycling of Fe 3+ are realized.

[0088] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions of the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A clayey sandstone uranium ore oxidation leaching system, 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 - chemical addition 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 is equipped with an acid - resistant submersible sewage pump I (30). The liquid preparation - chemical addition unit pool is used to circulate the leaching solution to the uranium leaching pool (1) and adjust the pH and 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, and the acid-resistant submersible pump II (50) recirculates the leaching solution back 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 - drainage.

2. The oxidized leaching system for argillaceous sandstone uranium ore according to claim 1, characterized in that, 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 the opening holes is 20 - 40 pieces / m.

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

4. The argillaceous sandstone uranium ore oxidation leaching system 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 - 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 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, and the acid-resistant submersible pump I (30) is communicated with the uranium leaching pool (1) through a liquid preparation pool outlet pipe (32) for circulating and transporting the leaching solution to the uranium leaching pool (1). The dosing tank (4) contains a chemical agent (40), and the chemical agent (40) 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 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, oxygen is intermittently supplied to the liquid collecting pipe (15) and the liquid collecting layer (12) through an aeration device, so that the dissolved oxygen is 5.0 - 8.0 mg / L, and the aeration intermittent period is 20 - 40% of the flooding duration. At the same time, the pH value of the leaching solution is adjusted to be between 2.0 and 2.5 to promote the oxidation of tetravalent uranium to hexavalent uranium by the Fe 3+ / O2 synergy and form 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 drying period, fresh air is introduced into the liquid collecting pipe (15) and the liquid collecting layer (12) to co-oxidize uranium remaining in the uranium ore with Fe 3+ Continue to co-oxidize uranium. After drying 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 drained into the recovery tank (2); (S4) Adsorption stage: In the recovery pool (2), use the 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 - medicine adding unit pool. (S5) Liquid preparation stage: In the liquid preparation - medicine adding 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, wherein 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 period, 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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