Equipment for recovering rhenium from flue dust

Abstract

The invention discloses equipment for recovering rhenium from flue dust. The equipment comprises a pretreatment unit, an adsorption unit, an elution unit, a collection unit and a control unit, the pretreatment unit is used for removing impurities and interfering ions through a stirring tank provided with a double-layer stirring paddle, two-stage filtration and an ion exchange column, and automatically adjusting the pH of slurry through a pH adjusting device so as to create an optimal adsorption environment; the adsorption unit adopts an adsorption column with a distributor at the top and a porous support plate at the bottom, and is matched with a circulating pump and online concentration detection, so that automatic reflux circulating adsorption is realized, and the adsorption is more thorough; the elution unit is provided with a metering pump and an automatic electric heating sleeve, so that the optimal elution temperature is provided for the filler layer of the adsorption column, and the elution is more efficient; the collecting unit is used for monitoring the concentration and flow of eluent and the liquid level of a collecting tank; by adopting the full-process automatic control efficient rhenium recovery equipment provided by the invention, the problems of low recovery efficiency, incomplete elution, poor pretreatment and the like in the prior art can be solved, and the rhenium recovery rate is remarkably improved.

Description

Technical Field

[0001] This application relates to the field of rare metal resource recycling technology, and in particular to a resin device for recovering rhenium from flue ash. Background Technology

[0002] Currently, resin equipment for recovering rhenium from flue gas ash mainly consists of a flue gas ash pretreatment unit, an adsorption column, an elution unit, and a collection unit. Specifically, the pretreatment unit is directly connected to the top of the adsorption column via a pipeline, the bottom of the adsorption column is connected to the elution unit via a pipeline, and the elution unit is connected to the collection unit via a pipeline.

[0003] The specific workflow is as follows: First, flue ash is fed into a pretreatment device, where it is mixed with water to form a flue ash slurry. After filtration to remove large particulate impurities, a rhenium-containing pretreatment solution is obtained. Next, the rhenium-containing pretreatment solution flows directly from the top of the adsorption column, which is filled with a conventional strong-base anion exchange resin. The pretreatment solution falls naturally into the adsorption column by gravity and comes into contact with the resin, which adsorbs the rhenium. After adsorption is complete, the eluent (usually a nitric acid solution) from the elution device enters the adsorption column to elute the resin containing the rhenium. Finally, the rhenium-containing eluent obtained from the elution flows into a collection device for collection, completing the rhenium recovery.

[0004] However, this device has the following drawbacks in practical applications:

[0005] 1. Low adsorption efficiency: In this equipment, the rhenium-containing pretreatment liquid falls naturally in the adsorption column by gravity alone. The contact time with the resin is short and the contact is insufficient. Some of the pretreatment liquid flows out of the adsorption column directly without fully reacting with the resin, resulting in a low adsorption rate of rhenium by the resin and failure to fully recover rhenium from the flue dust.

[0006] 2. Incomplete elution: After the eluent in the elution device enters the adsorption column, it cannot fully contact the resin adsorbed with rhenium due to the single flow pattern. Some of the rhenium adsorbed deep in the resin is difficult to be eluted, resulting in incomplete elution. This not only reduces the rhenium recovery rate but also affects the subsequent recycling of the resin.

[0007] 3. Poor pretreatment effect: Existing pretreatment devices only remove large particulate impurities through simple filtration. Fine impurities and some interfering ions (such as molybdenum ions) in flue ash slurry cannot be effectively removed. These impurities and interfering ions will adhere to the resin surface or compete with rhenium for adsorption sites, further reducing the resin's adsorption selectivity and adsorption efficiency for rhenium.

[0008] Therefore, it is necessary to propose a new technical solution to address the problems existing in the current technology. Summary of the Invention

[0009] This application provides a device for recovering rhenium from flue dust, which solves the problems of low adsorption efficiency and incomplete recovery of rhenium ions in existing devices.

[0010] To achieve the above objectives, this application provides the following technical solution:

[0011] This application provides an apparatus for recovering rhenium from flue dust, comprising:

[0012] The pretreatment unit includes a mixing tank, a filtration device, an ion exchange column, and a pH adjustment tank connected in sequence. The mixing tank is used to mix flue ash and water evenly to form a flue ash slurry. The filtration device is used to filter impurities in the flue ash slurry. The ion exchange column is filled with packing material to adsorb interfering ions in the filtered flue ash slurry. The bottom outlet of the ion exchange column is connected to the inlet of the pH adjustment tank. The pH adjustment tank is equipped with a pH adjustment device.

[0013] An adsorption unit includes an adsorption column and a circulation pump. A distributor is installed at the top inlet of the adsorption column, and the inlet of the distributor is connected to the outlet of the pH adjustment tank. The bottom outlet of the adsorption column is connected to the inlet of the circulation pump through a circulation pipe. A first rhenium concentration detector and a waste liquid discharge branch pipe are installed on the circulation pipe. The outlet of the circulation pump is connected to the reflux port located in the middle of the adsorption column.

[0014] The elution unit includes an eluent tank and a metering pump connected between the outlet of the eluent tank and the inlet of the distributor;

[0015] The collection unit includes a collection tank connected to the bottom outlet of the adsorption column via a collection pipe, and a flow meter and a second rhenium concentration detector installed on the collection pipe. A liquid level sensor is installed inside the collection tank.

[0016] The control unit is communicatively connected to the pretreatment unit, adsorption unit, elution unit, and collection unit, respectively.

[0017] Furthermore, in the above technical solution, the mixing tank is provided with a flue ash inlet, a water inlet, and a slurry outlet, and the slurry outlet is connected to the inlet end of the filter device; the mixing tank is equipped with a mixing device, which includes a mixing motor and a mixing shaft connected to the power output end of the mixing motor, the upper half of the mixing shaft is provided with a spiral mixing belt, and the lower half of the mixing shaft is provided with several mixing blades.

[0018] Furthermore, the filtration device includes a two-stage filter: the first-stage filter is a stainless steel filter screen with a pore size of 100 μm, and the second-stage filter is a ceramic filter membrane with a pore size of 10 μm; the ion exchange column includes a column shell and packing material filled inside the column shell, with a flue gas slurry inlet at the top of the column shell and a rhenium-rich liquid outlet at the bottom of the column shell, and the flue gas slurry inlet is connected to the outlet end of the ceramic filter membrane.

[0019] Furthermore, the pH adjustment device includes a pH detector installed in the pH adjustment tank, a hydrochloric acid dosing tank connected to the pH adjustment tank via a first dosing pipe, a first dosing pump installed on the first dosing pipe, a sodium hydroxide dosing tank connected to the pH adjustment tank via a second dosing pipe, and a second dosing pump installed on the second dosing pipe.

[0020] Furthermore, the pH adjustment tank is equipped with a stirrer.

[0021] Furthermore, the pH meter, the first dosing pump, the second dosing pump, and the agitator are all communicatively connected to the control unit. The control unit is configured to control the agitator and the first or second dosing pump to start according to the pH value measured by the pH meter, so as to adjust the pH value of the slurry in the pH adjustment tank to 7-8 to obtain a pretreated solution.

[0022] Furthermore, the adsorption column includes a columnar tube shell and a packing layer filled inside the columnar tube shell. The distributor is provided at the top inlet of the columnar tube shell, and a support plate is provided at the bottom of the columnar tube shell to prevent the packing layer from leaking out. The support plate has a porous structure.

[0023] Furthermore, the distributor is a perforated disc structure, with a hole diameter of 2-3 mm and a hole spacing of 5 mm.

[0024] Furthermore, the outlet end of the first rhenium concentration detector is provided with a T-junction, which is connected to the inlet of the circulation pump and the waste liquid discharge branch pipe respectively. A reflux circulation solenoid valve is provided between the T-junction and the circulation pump, and a waste discharge solenoid valve is provided on the waste liquid discharge branch pipe. The first rhenium concentration detector, the circulation pump, the reflux circulation solenoid valve, and the waste discharge solenoid valve are all communicatively connected to the control unit. The control unit is configured to compare the rhenium concentration of the adsorbed waste liquid obtained from the first rhenium concentration detector with the reference rhenium concentration, and control the circulation pump or the waste discharge solenoid valve to operate according to the comparison result.

[0025] Furthermore, an electric heating jacket is provided on the outer wall of the adsorption column, and a temperature sensor is provided inside the adsorption column. The electric heating jacket and the temperature sensor are respectively connected to the control unit. The control unit is configured to compare the temperature value obtained from the temperature sensor with a reference temperature value, and control the start and stop of the electric heating jacket according to the comparison result. The reference temperature value is the temperature at which the eluent and rhenium have the highest reactivity.

[0026] Furthermore, the eluent storage tank is equipped with a stirring mechanism.

[0027] Furthermore, the flow meter, the second rhenium concentration detector, and the liquid level sensor are respectively connected to the control unit. The flow meter is used to monitor the flow rate of the eluent in real time, the second rhenium concentration detector is used to monitor the rhenium concentration of the eluent, and the control unit is configured to compare the real-time liquid level obtained from the liquid level sensor with a set reference liquid level. If the real-time liquid level is equal to the set reference liquid level, an alarm signal is issued.

[0028] Compared with the prior art, this application has at least the following beneficial effects:

[0029] 1. This application effectively removes interfering ions and reduces competitive adsorption by setting an ion exchange column after the filtration device, thereby improving the selectivity of the resin packed in the subsequent adsorption column for rhenium; by adding a pH adjustment tank and configuring a pH adjustment device, the pH of the slurry is adjusted to the optimal adsorption range, improving the adsorption capacity and stability of the resin for rhenium in the adsorption column; by setting a distributor at the top inlet of the adsorption column, the liquid flows in evenly, avoiding channeling or short-circuiting and improving resin utilization efficiency; by setting a first rhenium concentration detector and a circulation pump to recirculate and adsorb the adsorption waste liquid with high rhenium concentration, the contact time between the liquid and the resin is extended, ensuring that rhenium is fully adsorbed; by setting a constant... The eluent is fed from the distributor into the adsorption column by a metering pump, precisely controlling the amount of eluent to avoid over- or under-eluent use and ensuring elution efficiency and economy. Therefore, this application solves the problem of low adsorption efficiency of existing equipment by "forced circulation by a circulating pump + uniform distribution by a distributor + automated control of concentration monitoring", solves the problem of incomplete elution by "precise supply of eluent by a metering pump + concentration monitoring", solves the problem of poor pretreatment effect by adding an ion exchange column for impurity removal and pH adjustment to optimize the adsorption environment, and achieves full-process automated control through a control unit, enhancing the automation level and operational stability of the equipment.

[0030] 2. The mixing device configured for the mixing tank in this application adopts a double-layer mixing structure. The lower half of the mixing shaft is equipped with several mixing blades, which can generate strong radial and tangential flow, quickly lifting and dispersing the solid particles at the bottom to prevent sedimentation, ensuring full contact between flue ash and water, and promoting the leaching of rhenium. The upper half of the mixing shaft is equipped with a spiral mixing belt, which can continuously transport the liquid and suspended matter in the middle and upper part downwards, forming a circulation with the lower blade area, eliminating mixing dead zones, and making the concentration and particle distribution of the slurry in the entire tank highly uniform, thereby providing a stable and uniformly dispersed feed for subsequent filtration and ion exchange.

[0031] 3. This application employs a two-stage filtration system. The first-stage filter (100μm stainless steel mesh) removes large particulate impurities, significantly reducing the mechanical load and clogging risk of the second-stage ceramic filter membrane. The second-stage filter (10μm ceramic filter membrane) deeply removes suspended solids and colloids (such as most fine flue dust particles and silicate colloids), producing a clear filtrate. This greatly reduces the solid content entering the ion exchange column, ensuring that the packing material (such as molybdenum removal resin) can have sufficient and direct contact with the target interfering ions, thereby improving ion exchange efficiency.

[0032] 4. This application constructs a closed-loop feedback system consisting of a pH meter (real-time monitoring), a control unit (analysis and judgment), and a dosing pump (actual adjustment). It is equipped with two dosing systems for hydrochloric acid and sodium hydroxide, allowing for precise bidirectional pH fine-tuning. This ensures that each batch of pretreatment solution entering the adsorption unit has a consistent and optimal pH chemical environment. At the optimal pH, the resin in the packing layer adsorbs rhenium most rapidly, fully utilizing the reflux circulation adsorption design of this application to reach adsorption equilibrium in a shorter time, improving adsorption efficiency and increasing equipment processing capacity. Furthermore, the control unit can automatically control the entire process of detection, calculation, dosing, and stirring, reducing manual intervention, operational errors, and labor costs.

[0033] 5. This application employs a porous disc distributor with a pore size of 2-3 mm and a pore spacing of 5 mm, which can disperse the liquid flow entering the adsorption column into a large number of fine liquid columns with similar flow velocities, and ensure that these liquid columns are evenly distributed in the packing layer. This can eliminate flow dead zones and short-circuit phenomena, so that the adsorption capacity of the entire packing layer is fully utilized. This application also sets a support plate under the entire packing layer to prevent the resin particles in the packing layer from being lost due to the impact of gravity, the start and stop of the circulating pump, and changes in flow direction. In addition, setting the support plate as a porous structure can ensure that the liquid (or eluent) after adsorption can be smoothly and evenly collected and flowed out, avoiding the formation of stagnation zones at the bottom.

[0034] 6. This application achieves automated reflux circulation adsorption through a first rhenium concentration detector, a circulation pump, a reflux circulation solenoid valve, and a waste discharge solenoid valve. When the rhenium concentration at the bottom outlet of the adsorption column is detected to be higher than the reference concentration, it indicates that the resin filled in the adsorption column is not yet saturated and still has adsorption capacity, but the rhenium in the liquid has not been fully adsorbed. At this time, the control unit opens the reflux circulation solenoid valve, closes the waste discharge solenoid valve, and starts the circulation pump to send this part of the "unqualified" liquid back into the adsorption column for continued adsorption. This greatly extends the contact time between the effective pretreatment liquid and the resin in the adsorption column, ensuring full adsorption.

[0035] 7. This application establishes a closed loop by using a temperature sensor (real-time monitoring), a control unit (comparison benchmark), and an electric heating mantle (execution control) to achieve constant temperature control of the elution process within the adsorption column. This stabilizes the temperature at the optimal "reference temperature," increases the diffusion coefficient of the eluent in the resin bed and the pores inside the resin particles, and allows the eluent to penetrate more effectively into the deeper layers of the resin particles, enabling more thorough and faster elution.

[0036] 8. This application uses detection devices such as pH meter, rhenium concentration meter, temperature sensor, flow meter and liquid level sensor to monitor key parameters (rhenium concentration, pH value, temperature, flow rate, etc.) in real time. The control unit automatically adjusts the operation of components such as circulation pump, metering pump, heating jacket, etc., without the need for frequent manual intervention, reducing the labor intensity of operators, avoiding human operation errors, and ensuring the stability and consistency of equipment operation. Therefore, the whole set of equipment has a high degree of automation and is easy to operate. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing this application. For example, based on the technical concepts disclosed in this application and the exemplary drawings, those skilled in the art are able to easily make conventional adjustments or further optimizations to the addition / reduction / classification, specific shapes, positional relationships, connection methods, and size ratios of certain units (components).

[0038] Figure 1 This is a schematic diagram of the process for recovering rhenium from flue ash provided in this application, as one embodiment.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Mixing tank; 2. First-stage filter; 3. Second-stage filter; 4. Ion exchange column; 5. pH adjustment device; 6. Distributor; 7. Adsorption column; 8. Electric heating mantle; 9. Support plate; 10. First rhenium concentration detector; 11. Waste liquid discharge branch pipe; 12. Circulation pump; 13. Return circulation solenoid valve; 14. Waste discharge solenoid valve; 15. Eluent storage tank; 16. Metering pump; 17. Flow meter; 18. Second rhenium concentration detector; 19. Collection tank. Detailed Implementation

[0041] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] In the description of this application: unless otherwise stated, "a plurality of" means two or more. The terms "first," "second," etc., in this application are intended to distinguish the objects referred to and do not have any special meaning in terms of technical connotation (e.g., they should not be construed as an emphasis on importance or order). Expressions such as "including," "comprising," and "having" also mean "not limited to" (certain units, components, materials, steps, etc.).

[0043] The terms used in this application, such as "upper," "lower," "left," "right," and "middle," are generally used to facilitate intuitive understanding by referring to the accompanying drawings, and are not absolute limitations on the positional relationships in the actual product. Changes in these relative positional relationships, without departing from the technical concept disclosed in this application, should also be considered within the scope of this application.

[0044] This application provides a device for recovering rhenium from flue gas ash. Based on traditional equipment, improvements have been made to the pretreatment device, adsorption column structure, and elution device. A circulation device and a detection device are also included to address the problems of low adsorption efficiency, incomplete elution, and poor pretreatment effect in existing equipment. Furthermore, the device's automation level is improved, and production labor costs are reduced. The structural principle of this device will be described in detail below with reference to specific embodiments and accompanying drawings.

[0045] See Figure 1 The device for recovering rhenium from flue dust provided in this application mainly includes: a control unit and a pretreatment unit, an adsorption unit, an elution unit and a collection unit that are respectively connected to the control unit in communication.

[0046] I. Preprocessing Unit

[0047] The pretreatment unit includes a stirred tank 1, a filter device, an ion exchange column 4, and a pH adjustment tank connected in sequence.

[0048] The mixing tank 1 is used to mix flue ash and water at a mass ratio of 1:5, and to stir them evenly with the agitator on it to form a flue ash slurry. The mixing tank 1 is equipped with a flue ash inlet, a water inlet, and a slurry outlet, and the slurry outlet is connected to the inlet end of the filter device.

[0049] The mixing device includes a mixing motor (connected to a control unit signal, and the mixing speed can be adjusted by the control unit) and a mixing shaft connected to the power output end of the mixing motor. The upper half of the mixing shaft is equipped with a spiral mixing belt, and the lower half of the mixing shaft is equipped with several mixing blades.

[0050] Because flue ash has uneven density and is prone to sedimentation and agglomeration, uneven mixing can lead to uneven loading in subsequent filtration and ion exchange processes, resulting in some rhenium being filtered out without sufficient dissolution. This application addresses this issue by using a lower stirring impeller to generate strong radial and tangential flow, rapidly lifting and dispersing solid particles at the bottom to prevent sedimentation and ensure sufficient contact between the flue ash and water, promoting rhenium leaching. Simultaneously, the upper spiral stirring belt continuously transports the liquid and suspended solids from the upper middle section downwards, forming a circulation with the lower impeller area, eliminating mixing dead zones, and ensuring uniform slurry concentration and particle distribution throughout the tank. This provides a stable and uniformly dispersed feed for subsequent filtration and ion exchange units. Furthermore, the spiral mixing belt generates a powerful axial pumping capacity during rotation, actively pushing the uniformly mixed slurry towards the outlet at the bottom of the tank. This "active discharge" mode avoids the segregation phenomenon of "clear liquid flowing first, thick slurry lagging behind" that may occur when discharging solely by gravity, ensuring a constant discharge concentration. This protects the stable operation of downstream filtration devices, reduces the risk of pipeline blockage, and guarantees the continuity and stability of the pretreatment process. Therefore, this application fundamentally improves the preparation quality of flue gas ash slurry through the synergistic effect of spiral conveying and shear mixing, solving potential problems such as uneven mixing and discharge fluctuations in raw material pretreatment, and providing high-quality materials for subsequent processes.

[0051] The filtration device is used to filter impurities in flue gas ash slurry. It employs a two-stage filter. The first-stage filter 2 is a stainless steel mesh with a pore size of 100 μm, which removes large particulate impurities from the slurry (such as larger solid particles remaining in the slurry after stirring, undispersed clumps, etc.). The second-stage filter 3 is a ceramic membrane with a pore size of 10 μm, which further filters fine impurities (such as most fine flue gas ash particles, silicate colloids, etc.), preventing impurities from entering the subsequent adsorption stage and clogging the resin pores. Therefore, this application minimizes the impact of physical impurities through multi-stage filtration, providing a stable slurry for subsequent stages.

[0052] The ion exchange column 4 includes a column shell and packing material filled inside the column shell. The top of the column shell has a flue gas slurry inlet, and the bottom has a rhenium-rich solution outlet. The flue gas slurry inlet is connected to the outlet end of the ceramic filter membrane. The packing material inside the ion exchange column 4 can adsorb interfering ions in the filtered flue gas slurry. The bottom outlet of the ion exchange column 4 is connected to the inlet of the pH adjustment tank.

[0053] The filler material mentioned above can be a modified aminophosphonic acid chelating resin, which can specifically adsorb molybdenum ions (interfering ions) in the slurry. When the rhenium-containing slurry flows through the ion exchange column 4, the molybdenum ions are adsorbed by the resin, while the rhenium ions pass through smoothly, thereby improving the selectivity of the resin for rhenium in the subsequent adsorption process.

[0054] In other embodiments, the filler described above can also be an oxime chelating resin (such as LIX84I), which also has good adsorption selectivity for molybdenum ions. Under pH conditions of 5-7, the molybdenum ion removal rate can reach more than 88%, which is slightly lower than that of modified aminophosphonic acid chelating resin (more than 90%), but the cost is lower and it is suitable for cost-sensitive scenarios.

[0055] This application defines the ion exchange column 4 as an independent unit (column shell + packing material) and directly connects it to the ceramic filter membrane outlet. This forms a continuous, closed process from physical impurity removal (filtration) to chemical impurity removal (ion exchange), resulting in higher processing efficiency. Furthermore, the ion exchange column 4 reduces the burden on the subsequent adsorption column 7, allowing the resin in the adsorption column 7 to almost exclusively adsorb rhenium ions. This significantly increases the resin's adsorption capacity and rate for rhenium, preventing impurity ions such as molybdenum from firmly occupying resin sites in the adsorption column 7. This leads to more thorough elution and regeneration of the main adsorption resin, a longer cycle life, and improved pretreatment efficiency. Compared to the simple filtration of traditional pretreatment devices, the ion exchange column 4 in this application's pretreatment unit produces a high-quality rhenium-rich solution with low solid content and low interfering ions. This allows the subsequent cyclic adsorption scheme to focus entirely on the mass transfer process of rhenium, resulting in extremely high adsorption efficiency.

[0056] The pH adjustment tank is mainly used to store the rhenium-rich solution discharged from ion exchange column 4. The pH adjustment tank is equipped with a pH adjustment device 5 and a stirrer.

[0057] In a preferred embodiment of this application, the pH adjustment device 5 includes a pH detector installed in a pH adjustment tank, a hydrochloric acid dosing tank connected to the pH adjustment tank via a first dosing pipe, a first dosing pump installed on the first dosing pipe, a sodium hydroxide dosing tank connected to the pH adjustment tank via a second dosing pipe, and a second dosing pump installed on the second dosing pipe.

[0058] The pH meter, the first dosing pump, the second dosing pump, and the agitator are all connected to the control unit. The control unit can control the agitator and either the first or second dosing pump to start based on the pH value measured by the pH meter, adjusting the pH of the slurry in the pH adjustment tank to 7-8 to obtain the pretreated solution. In other words, the control unit of this application can automatically control the entire process of detection, calculation, dosing, and agitation, reducing manual intervention, operational errors, and labor intensity.

[0059] II. Adsorption Unit

[0060] The adsorption unit mainly includes an adsorption column 7, a circulation pump 12, and a first rhenium concentration detector 10. Specifically, this application provides a distributor 6 at the top inlet of the adsorption column 7. The inlet of the distributor 6 is connected to the outlet of the pH adjustment tank. The bottom outlet of the adsorption column 7 is connected to the inlet of the circulation pump 12 through a circulation pipe. The first rhenium concentration detector 10 and a waste liquid discharge branch pipe 11 are installed on the circulation pipe. The outlet of the circulation pump 12 is connected to the reflux port located in the middle of the adsorption column 7.

[0061] In a preferred embodiment of this application, the adsorption column 7 includes a columnar tube shell and a packing layer filled inside the columnar tube shell. A distributor 6 is provided at the top inlet of the columnar tube shell, and a support plate 9 is provided at the bottom of the columnar tube shell to prevent the packing layer from leaking out. The support plate 9 has a porous structure (pore diameter 0.2 mm to prevent resin leakage). The distributor 6 is a porous disc structure with pore diameters of 2-3 mm and pore spacing of 5 mm. The packing layer is filled with a novel macroporous weakly basic anion exchange resin (model D301-G) with a resin particle size of 0.4-0.6 mm and a specific surface area of ​​800-1000 m². 2 / g, with an adsorption capacity that is more than 30% higher than that of existing conventional resins.

[0062] In other embodiments, the packing layer inside the adsorption column 7 is filled with a gel-type strong-base anion exchange resin (such as 201×7 resin), which has a high adsorption capacity for rhenium in a high-concentration chloride ion environment, although its specific surface area (500~600m²) is relatively large. 2 While its adsorption efficiency ( / g) is lower than that of D301-G resin, it can be comparable to that of D301-G resin when the chloride ion content in flue ash is high. It can be selected for use according to the specific composition of flue ash.

[0063] The outlet of the first rhenium concentration detector 10 is equipped with a T-junction, which is connected to the inlet of the circulation pump 12 and the waste liquid discharge branch pipe 11. A reflux solenoid valve 13 is installed between the T-junction and the circulation pump 12, and a waste discharge solenoid valve 14 is installed on the waste liquid discharge branch pipe 11. The first rhenium concentration detector 10, the circulation pump 12, the reflux solenoid valve 13, and the waste discharge solenoid valve 14 are all communicatively connected to the control unit. The control unit can compare the rhenium concentration of the adsorbed waste liquid obtained from the first rhenium concentration detector 10 with the reference rhenium concentration, and control the circulation pump 12 or the waste discharge solenoid valve 14 to operate based on the comparison result. The control unit can also adjust the flow rate of the circulation pump 12.

[0064] Therefore, this application monitors the rhenium concentration at the bottom outlet of adsorption column 7 in real time and compares it with a preset reference rhenium concentration. When the outlet rhenium concentration is detected to be higher than the reference concentration, it indicates that the resin in adsorption column 7 is not yet saturated and still has adsorption capacity, but the rhenium in the liquid has not been fully adsorbed. At this time, the control unit opens the reflux circulation solenoid valve 13, closes the waste discharge solenoid valve 14, and starts the circulation pump 12 to pump this part of the "unqualified" liquid back into the column for continued adsorption. This greatly extends the effective contact time between the liquid and the resin, achieving complete adsorption. When the outlet rhenium concentration is detected to be lower than or equal to the reference concentration, it indicates that the current liquid has been purified to the standard. At this time, the control unit closes the reflux circulation solenoid valve 13, opens the waste discharge solenoid valve 14, and shuts down the circulation pump 12 to discharge the qualified waste liquid. During continuous feeding, if the outlet concentration remains higher than the reference concentration and cannot decrease even after circulation, it may indicate that the resin is close to saturation. This can serve as an important signal to trigger the system to stop feeding and prepare to enter the elution stage.

[0065] In other embodiments, a pneumatic diaphragm pump can be used instead of the circulation pump 12. The pneumatic diaphragm pump is characterized by being leak-free and easy to maintain, and is suitable for pretreatment liquid scenarios with strong corrosiveness. Although its initial cost is higher than that of the circulation pump 12, it has a longer service life and can reduce long-term maintenance costs.

[0066] III. Elution Unit

[0067] The elution unit mainly includes an eluent storage tank 15 (the eluent can be a 5%~8% nitric acid solution) and a metering pump 16 connected between the outlet of the eluent storage tank 15 and the inlet of the distributor 6.

[0068] As an alternative, a 3% to 5% sulfuric acid solution can be used as the eluent. This eluent can achieve a rhenium elution rate of over 95% at a temperature of 35 to 45°C. Although the elution temperature is slightly lower than that of nitric acid solution (40 to 50°C), sulfuric acid solution is more stable, less volatile, and can reduce corrosion to equipment and improve operational safety.

[0069] To ensure thorough elution, this application also includes an electric heating jacket 8 (specifically covering the packing layer area) on the outer wall of the adsorption column 7, and a temperature sensor inside the adsorption column 7. The electric heating jacket 8 and the temperature sensor are respectively connected to the control unit. The control unit can compare the temperature value obtained from the temperature sensor with a reference temperature value (which can be set between 40 and 50°C, within which the reactivity of the eluent with rhenium is increased, and the elution efficiency is improved by more than 25%), and control the start and stop of the electric heating jacket 8 according to the comparison result, that is, adjust the temperature in real time according to the elution situation.

[0070] This application utilizes a closed-loop system consisting of a temperature sensor (for real-time monitoring), a control unit (for comparison), and an electric heating jacket 8 (for control execution) to achieve constant temperature control of the elution process within the adsorption column 7. This maintains the temperature stably at the optimal "reference temperature," increasing the diffusion coefficient of the eluent in the resin bed and the pores within the resin particles, allowing the eluent to penetrate more effectively into the deeper layers of the resin particles. Furthermore, the combination of a metering pump 16 and the heating jacket ensures a thorough reaction between the eluent and the resin, resulting in more complete and faster elution.

[0071] Since the concentration of nitric acid solution may change locally due to volatilization or slight decomposition when left to stand for a long time, this application equips the eluent storage tank 15 with a stirring mechanism to ensure uniform eluent concentration.

[0072] The metering pump 16 in this application can be connected to the control unit. The metering pump 16 can accurately control the flow rate of the eluent (5~15L / h), avoiding insufficient contact between the eluent and the resin due to excessively fast flow rate, or affecting the elution efficiency due to excessively slow flow rate.

[0073] The elution process is as follows: the metering pump 16 sends the eluent from the top of the adsorption column 7. Under the temperature control of the electric heating jacket 8, the eluent slowly flows through the packing layer and reacts fully with the resin adsorbed with rhenium. The rhenium-containing eluent flows out from the bottom of the column and enters the collection tank 19.

[0074] In a preferred embodiment of this application, the elution unit may be equipped with a circulating elution system, such as a circulating pump 12, and the rhenium concentration in the eluent may be monitored in real time by a second rhenium concentration detector 18. When the concentration drops to a set threshold, it indicates that the rhenium in the resin has been basically eluted, and the elution is deemed complete.

[0075] IV. Collection Unit

[0076] The collection unit mainly includes a collection tank 19 connected to the bottom outlet of the adsorption column 7 via a collection pipe, and a flow meter 17 and a second rhenium concentration detector 18 installed on the collection pipe. A level sensor is installed inside the collection tank 19. The flow meter 17, the second rhenium concentration detector 18, and the level sensor are all communicatively connected to the control unit. The flow meter 17 monitors the flow rate of the eluent in real time, the second rhenium concentration detector 18 monitors the rhenium concentration of the eluent, and the control unit compares the real-time level obtained from the level sensor with a set reference level. If the real-time level equals the set reference level, an alarm signal is issued. By monitoring the collection tank level in real time, overflow accidents caused by valve malfunction, misoperation, or incorrect flow estimation can be prevented, ensuring production safety and environmental safety. The alarm can also trigger an emergency stop for upstream equipment to stop the liquid intake.

[0077] Therefore, compared with traditional equipment, this application has completed the optimization of the entire process from intelligent pretreatment, efficient adsorption, thorough elution, safety monitoring and data collection, which has enabled the entire process of recovering rhenium from flue ash to be upgraded to be efficient, thorough, safe and automated.

[0078] Furthermore, this application incorporates a distributor at the top of the adsorption column to uniformly disperse the rhenium-containing pretreatment solution, avoiding channeling and increasing the contact area with the resin. Simultaneously, a new circulation device is added to circulate and adsorb insufficiently adsorbed pretreatment solution, extending the contact time. Internal experiments have verified that, compared to existing technologies, this equipment increases the rhenium adsorption rate from 75%–80% to over 95%, effectively recovering rhenium from flue gas ash. Moreover, the ion exchange column 4 in the pretreatment device removes interfering molybdenum ions and adjusts the pH to the optimal adsorption range, further improving the resin's selectivity for rhenium adsorption. During adsorption, the resin's selectivity coefficient for rhenium (relative to molybdenum) increases from 15 in the prior art to 40.

[0079] Furthermore, this application incorporates a metering pump 16 in the elution unit to precisely control the eluent flow rate, ensuring sufficient contact between the eluent and the resin. An electric heating mantle 8 maintains the temperature of the adsorption column 7 at the optimal elution temperature, enhancing the reactivity of the eluent with rhenium. Experimental data show that this equipment increases the rhenium elution rate from 80%–85% in existing technologies to over 98%, and the residual rhenium content in the eluted resin is below 0.05 mg / g, allowing for direct recycling and reducing resin replacement costs.

[0080] In addition, this application incorporates a two-stage filtration system in the pretreatment unit to remove impurities of different particle sizes, preventing them from clogging the resin pores. The ion exchange column 4 specifically adsorbs interfering molybdenum ions, reducing the competitive adsorption of molybdenum and rhenium. The pH adjustment device 5 adjusts the slurry pH to the optimal range, creating favorable conditions for subsequent adsorption. After pretreatment, the impurity content in the slurry is below 0.1%, and the molybdenum ion removal rate reaches over 90%, effectively improving the efficiency and selectivity of subsequent adsorption stages.

[0081] Furthermore, this application uses detection devices such as pH meter, rhenium concentration meter, temperature sensor, flow meter and liquid level sensor to monitor key parameters (rhenium concentration, pH value, temperature, flow rate, etc.) in real time. The control unit automatically adjusts the operation of components such as circulation pump, metering pump, heating jacket, etc., without the need for frequent manual intervention, reducing the labor intensity of operators, avoiding human operation errors, and ensuring the stability and consistency of equipment operation. Therefore, the whole set of equipment has a high degree of automation and is easy to operate.

[0082] The technical features of the above embodiments can be combined in any way (as long as there is no contradiction in the combination of these technical features). For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described; these embodiments not explicitly written should also be considered to be within the scope of this specification.

[0083] The present application has been described in a relatively specific and detailed manner above through general descriptions and specific embodiments. It should be understood that, based on the technical concept of the present application, several conventional adjustments or further innovations can be made to these specific embodiments; however, as long as they do not depart from the technical concept of the present application, the technical solutions obtained by these conventional adjustments or further innovations also fall within the protection scope of the claims of the present application.

Claims

1. A device for recovering rhenium from flue ash, characterized in that, include: The pretreatment unit includes a stirred tank, a filter, an ion exchange column, and a pH adjustment tank connected in sequence. The mixing tank is used to mix flue ash and water evenly to form flue ash slurry. The filtration device is used to filter impurities in the flue ash slurry. The ion exchange column is filled with packing material to adsorb interfering ions in the filtered flue ash slurry. The bottom outlet of the ion exchange column is connected to the inlet of the pH adjustment tank. The pH adjustment tank is equipped with a pH adjustment device. An adsorption unit includes an adsorption column and a circulation pump. A distributor is installed at the top inlet of the adsorption column, and the inlet of the distributor is connected to the outlet of the pH adjustment tank. The bottom outlet of the adsorption column is connected to the inlet of the circulation pump through a circulation pipe. A first rhenium concentration detector and a waste liquid discharge branch pipe are installed on the circulation pipe. The outlet of the circulation pump is connected to the reflux port located in the middle of the adsorption column. The elution unit includes an eluent tank and a metering pump connected between the outlet of the eluent tank and the inlet of the distributor; The collection unit includes a collection tank connected to the bottom outlet of the adsorption column via a collection pipe, and a flow meter and a second rhenium concentration detector installed on the collection pipe. A liquid level sensor is installed inside the collection tank. The control unit is communicatively connected to the pretreatment unit, adsorption unit, elution unit, and collection unit, respectively.

2. The apparatus for recovering rhenium from flue ash according to claim 1, characterized in that, The mixing tank is provided with a flue ash inlet, a water inlet, and a slurry outlet. The slurry outlet is connected to the inlet end of the filter device. The mixing tank is equipped with a mixing device, which includes a mixing motor and a mixing shaft connected to the power output end of the mixing motor. The upper half of the mixing shaft is provided with a spiral mixing belt, and the lower half of the mixing shaft is provided with several mixing blades.

3. The apparatus for recovering rhenium from flue ash according to claim 1 or 2, characterized in that, The filtration device includes two-stage filters: the first-stage filter is a stainless steel filter screen with a pore size of 100μm, and the second-stage filter is a ceramic filter membrane with a pore size of 10μm. The ion exchange column includes a column shell and packing material filled inside the column shell. The top of the column shell is provided with a flue ash slurry inlet, and the bottom of the column shell is provided with a rhenium-rich liquid outlet. The flue ash slurry inlet is connected to the outlet end of the ceramic filter membrane.

4. The apparatus for recovering rhenium from flue ash according to claim 1 or 2, characterized in that, The pH adjustment device includes a pH detector installed in the pH adjustment tank, a hydrochloric acid dosing tank connected to the pH adjustment tank via a first dosing pipe, a first dosing pump installed on the first dosing pipe, a sodium hydroxide dosing tank connected to the pH adjustment tank via a second dosing pipe, and a second dosing pump installed on the second dosing pipe. The pH adjustment tank is equipped with a stirrer; The pH meter, the first dosing pump, the second dosing pump, and the stirrer are all communicatively connected to the control unit. The control unit is configured to start the stirrer and the first or second dosing pump according to the pH value measured by the pH detector, so as to adjust the pH value of the slurry in the pH adjustment tank to 7-8 and obtain the pretreated liquid.

5. The apparatus for recovering rhenium from flue ash according to claim 1, characterized in that, The adsorption column includes a columnar tube shell and a packing layer filled inside the columnar tube shell. The distributor is provided at the top inlet of the columnar tube shell, and a support plate is provided at the bottom of the columnar tube shell to prevent the packing layer from leaking out. The support plate has a porous structure. The distributor is a perforated disc structure with holes of 2-3 mm in diameter and 5 mm in spacing.

6. The apparatus for recovering rhenium from flue ash according to claim 1 or 5, characterized in that, The outlet end of the first rhenium concentration detector is provided with a three-way valve, which is connected to the inlet of the circulation pump and the waste liquid discharge branch pipe respectively. A reflux circulation solenoid valve is provided between the three-way valve and the circulation pump, and a waste discharge solenoid valve is provided on the waste liquid discharge branch pipe. The first rhenium concentration detector, the circulating pump, the reflux solenoid valve, and the waste discharge solenoid valve are all communicatively connected to the control unit. The control unit is configured to compare the rhenium concentration of the adsorbed waste liquid obtained from the first rhenium concentration detector with the reference rhenium concentration, and control the operation of the circulating pump or the waste discharge solenoid valve according to the comparison result.

7. The apparatus for recovering rhenium from flue ash according to claim 1 or 5, characterized in that, An electric heating jacket is provided on the outer wall of the adsorption column, and a temperature sensor is provided inside the adsorption column. The electric heating jacket and the temperature sensor are respectively connected to the control unit. The control unit is configured to compare the temperature value obtained from the temperature sensor with a reference temperature value, and control the start and stop of the electric heating jacket according to the comparison result. The reference temperature value is the temperature at which the eluent and rhenium have the highest reactivity. The eluent storage tank is equipped with a stirring mechanism.

8. The apparatus for recovering rhenium from flue ash according to claim 1, characterized in that, The flow meter, the second rhenium concentration detector, and the liquid level sensor are respectively connected to the control unit. The flow meter is used to monitor the flow rate of the eluent in real time, the second rhenium concentration detector is used to monitor the rhenium concentration of the eluent, and the control unit is configured to compare the real-time liquid level obtained from the liquid level sensor with a set reference liquid level. If the real-time liquid level is equal to the set reference liquid level, an alarm message is output.

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