Equipment for preparing high-purity ammonium rhenate by directly purifying low-concentration rhenium solution

Abstract

The invention discloses equipment for preparing high-purity ammonium rhenate by directly purifying a low-concentration rhenium solution. The equipment comprises a feeding unit, a resin pretreatment unit, an adsorption unit, a directional impurity removal unit, a sectional elution unit, a circulating enrichment unit and an evaporative crystallization unit which are controlled by a control unit in a centralized manner, a resin pretreatment unit with an annular distributor is arranged at the top of the adsorption column, uniform backwashing and ammonium activation are realized, impurities are selectively removed through a directional impurity removal unit after adsorption, and low-concentration eluent flows back to the adsorption column for secondary adsorption and enrichment through a sectional elution and circulating enrichment unit; feeding the high-concentration rhenium-rich liquid into an evaporative crystallization unit, and returning mother liquid to a system for circulation; therefore, through integrated integration and full-process automatic control, efficient adsorption, deep impurity removal, internal circulation concentration and high-purity crystallization of low-concentration rhenium are achieved, and the technical problems that in a traditional process, the adsorption rate is low, the product purity is insufficient, high-energy-consumption external concentration equipment is depended on, and operation is complex are solved.

Description

Technical Field

[0001] This application relates to the field of rare metal resource recycling technology, and in particular to an apparatus capable of directly purifying and preparing high-purity ammonium perrhenate from low-concentration rhenium solutions. Background Technology

[0002] Currently, the recovery of rhenium from low-concentration rhenium-containing solutions such as pickling solutions in copper smelting flue gas and the preparation of high-purity ammonium perrhenate mainly relies on ion exchange adsorption and elution processes, primarily using adsorption equipment with specialized resins such as Tulsimer® RCX-5143 as the core.

[0003] An existing adsorption device mainly includes: a single-stage glass adsorption column, a peristaltic pump for conveying the feed solution, a storage tank for storing regenerant (such as 5% NH4OH or NaOH), and an open collection tank for collecting the eluent. The basic process flow is as follows: a low-concentration rhenium solution is pumped into the adsorption column via the peristaltic pump; the resin selectively adsorbs rhenium ions; after adsorption saturation, the resin is directly eluted using a regenerant (such as NH4OH) to obtain a rhenium-containing eluent; after collection, the eluent needs to be transported to an external evaporation and concentration device for concentration before subsequent ammonium rheniumate crystallization can proceed.

[0004] However, the backwashing and activation processes of the adsorption column in this device rely solely on gravity or simple pipelines, resulting in severely uneven distribution of backwash water and regenerant in the resin bed. The resin expansion rate fluctuates by up to ±10%, which directly leads to the resin activation rate typically being below 80%. For low-concentration rhenium solutions of 22~28 mg / L, the adsorption rate is difficult to exceed 85%, and the resin potential has not been fully exploited, becoming a bottleneck for the efficiency and stability of the entire recovery process.

[0005] Another existing device includes: a D296 resin adsorption column, a Tulsimer® RCX-5143 resin adsorption column (two columns arranged independently), multiple peristaltic pumps (for delivering feed liquid / regenerant separately), and multiple open storage tanks (for storing feed liquid / eluent / impurities separately). This device has the following drawbacks: the two resin columns lack an integrated frame, resulting in complex piping connections (requiring more than 8 sections of flexible tubing, prone to leakage); there is no unified flow rate control module, and the flow rate deviation between the two columns >2 BV / h leads to fluctuations in adsorption efficiency; SO4 in the resin eluent... 2- Bi 3+ When the concentration is greater than 0.5 mg / L, external filtration equipment (such as a precision filter) is required to improve the purity, resulting in more process breakpoints and higher operational complexity.

[0006] In addition, there is another type of equipment that relies on a "single-effect or double-effect evaporator" to concentrate low-concentration eluent (Re < 200 mg / L) to > 2 g / L. However, this equipment is large in size (occupying more than 10 m²), consumes a lot of energy (> 250 kWh / m³), and has a Re loss rate of more than 5% due to water vapor evaporation. It cannot be integrated with the adsorption-elution equipment.

[0007] Therefore, existing equipment has a series of structural and technological defects in practical applications, which makes it difficult to meet the high standards of industrial production in terms of rhenium recovery efficiency, product purity and economic efficiency. It is necessary to propose a new technical solution to solve the problems existing in the existing technology. Summary of the Invention

[0008] This application provides a device for directly purifying low-concentration rhenium solution to prepare high-purity ammonium perrylate, in order to solve the problems of low recovery efficiency, low product purity and high energy consumption of existing rhenium extraction equipment.

[0009] To achieve the above objectives, this application provides the following technical solution:

[0010] This application provides an apparatus for the direct purification of low-concentration rhenium solution to prepare high-purity ammonium rhenium, including a control unit, and a feeding unit, a resin pretreatment unit, an adsorption unit, a directional impurity removal unit, a segmented elution unit, a circulating enrichment unit, and an evaporation crystallization unit, which are respectively communicatively connected to the control unit.

[0011] The feeding unit includes a raw material liquid storage tank, and the bottom outlet of the raw material liquid storage tank is connected to the top inlet of the adsorption column via a peristaltic pump.

[0012] The resin pretreatment unit includes an annular distributor located at the top feed inlet of the adsorption column, a dual-channel water inlet module located at the inlet end of the annular distributor, and a bed height sensor located inside the adsorption column. The dual-channel water inlet module includes a backwash deionization pipeline and a regenerator pipeline.

[0013] The adsorption unit includes the adsorption column, which is filled with a resin bed, and the bottom outlet of the adsorption column is provided with an eluent distribution valve.

[0014] The directional impurity removal unit includes an impurity removal agent storage tank, a mixer, and a diaphragm pump. The outlet end of the mixer is connected to the top feed inlet of the adsorption column.

[0015] The segmented elution unit includes an eluent storage tank, a metering pump, and an eluent distribution valve. The outlet of the metering pump is connected to the inlet of the adsorption column. The eluent distribution valve has a waste liquid outlet, a first-stage eluent outlet, and a final circulating eluent outlet.

[0016] The circulating enrichment unit includes a buffer tank, a reflux pump, and a check valve. The inlet of the buffer tank is connected to the outlet of the first stage eluent, and the outlet of the reflux pump is connected to the raw material storage tank.

[0017] The evaporation crystallization unit includes a vacuum evaporation crystallization device, whose inlet is connected to the outlet of the final circulating eluent, and whose mother liquor outlet is connected to the raw material liquid storage tank.

[0018] Furthermore, in the above technical solution, a first valve is provided on the pipeline between the bottom outlet of the raw material liquid storage tank and the peristaltic pump; a first liquid level sensor and a breather valve are provided on the top of the raw material liquid storage tank, the first liquid level sensor is communicatively connected to the control unit, and the control unit is configured to adjust the opening degree of the first valve according to the signal of the first liquid level sensor to adjust the discharge rate.

[0019] Furthermore, the raw material storage tank is also provided with a raw material inlet, a circulating liquid inlet, and a mother liquor reflux port; the circulating liquid inlet is connected to the reflux pump outlet of the circulating enrichment unit to receive low-concentration rhenium-rich solution for secondary adsorption; the mother liquor reflux port is connected to the mother liquor outlet of the evaporation crystallization unit.

[0020] Furthermore, the annular distributor is a perforated plate with multiple through holes evenly distributed along its circumference.

[0021] Furthermore, the inlet end of the backwash deionization pipeline is connected to a deionized water source, and a first flow valve is provided on the backwash deionization pipeline; a first metering valve is provided on the regenerant pipeline; the first flow valve, the first metering valve, and the bed height sensor are all communicatively connected to the control unit; the control unit is configured to control the first flow valve to operate according to the bed height signal obtained from the bed height sensor, thereby realizing the pretreatment of the resin.

[0022] Furthermore, the columnar shell of the adsorption column is made of borosilicate glass, and a double-layer sintered glass retention layer is provided at its bottom; an electric heating belt is wound around the outer wall of the adsorption column, and the electric heating belt is communicatively connected to the control unit to maintain the adsorption process temperature at 25~30℃.

[0023] Furthermore, the adsorption column is provided with multiple sampling ports at equal intervals along its height direction, and each sampling port is connected to a sampling valve group. The sampling valve group is communicatively connected to the control unit. The control unit is configured to control each sampling valve group to automatically sample after passing through twice the bed volume of liquid, and to determine the adsorption endpoint of the resin based on the detected rhenium concentration.

[0024] Furthermore, the impurity removal agent stored in the impurity removal agent storage tank is a 1 mol / L NaOH solution, and a second liquid level sensor is installed in the impurity removal agent storage tank; the mixer is equipped with a stirring device, and the mixer has an impurity removal agent inlet and a water inlet, and the stirring device is used to uniformly mix the impurity removal agent with water.

[0025] Furthermore, the eluent storage tank stores NH4OH solution, and a constant temperature jacket is provided outside the eluent storage tank; the solution in the eluent storage tank is pumped to the top inlet of the adsorption column by the metering pump.

[0026] Furthermore, the buffer tank is equipped with a third liquid level sensor and a stirrer.

[0027] Furthermore, the eluent distribution valve is communicatively connected to the control unit, which is configured to execute a segmented elution and cyclic enrichment control program, specifically including:

[0028] After the directional impurity removal unit completes the removal of impurity ions from the resin, the metering pump is controlled to pump the eluent into the adsorption column, and the eluent distribution valve is controlled to switch its outlet to the first section eluent outlet.

[0029] The low-concentration rhenium solution obtained from the first elution stage is collected into the buffer tank of the circulating enrichment unit;

[0030] Subsequently, the reflux pump is controlled to pump the low-concentration rhenium solution in the buffer tank back to the raw material storage tank, where it is mixed with the raw material solution and then transported back to the adsorption column by the peristaltic pump for secondary adsorption.

[0031] After completing a preset number of cycles or reaching a preset concentration, the eluent distribution valve is controlled to switch its outlet to the final circulating eluent outlet, and the rhenium-rich solution is transported to the evaporation and crystallization unit.

[0032] Furthermore, the mother liquor outlet of the vacuum evaporation crystallization device is equipped with a reflux valve for returning the crystallized mother liquor to the raw material storage tank.

[0033] Compared with the prior art, this application has at least the following beneficial effects:

[0034] 1. Based on further analysis and research of the prior art, this application recognizes that the existing rhenium extraction equipment has insufficient adsorption, poor resin backwashing activation effect, and many impurities in the eluent that need to be filtered. Moreover, the rhenium concentration in the eluent is not high and mainly relies on evaporation and crystallization devices for evaporation and crystallization, and the content of crystallized impurities is relatively high. Therefore, the existing equipment is not effective in purifying low-concentration rhenium solutions. Therefore, this application provides a purification device suitable for low-concentration rhenium solutions. By specifically setting a resin pretreatment unit at the top of the adsorption column, and employing a ring distributor and a dual-inlet water module, the device achieves "backwashing expansion" and "ammonium form activation" of the resin. Deionized water and regenerator, after passing through the ring distributor, enter the resin bed in a large quantity of fine, uniform liquid streams, completely eliminating "channeling" and distribution dead zones. This results in uniform and controllable resin bed expansion (expansion rate stable at 50%~60%), thorough ammonium form conversion, and a stable resin activation rate exceeding 95%, laying the foundation for subsequent high-efficiency adsorption. Furthermore, this application adds a directional impurity removal unit after adsorption and before elution to directionally remove impurities from the adsorption-saturated resin, leaving mainly high-purity rhenium on the resin. The resulting rhenium-rich solution obtained during subsequent elution has extremely low impurity content, effectively improving the efficiency of adsorption. The final purity of ammonium perrye crystals is high. Furthermore, this application innovatively incorporates a closed-loop linkage design between the segmented elution unit, the circulating enrichment unit, and the adsorption unit. The first stage eluent (low-concentration rhenium solution) of the segmented elution is returned to the feed end of the adsorption column for secondary adsorption. After multiple cycles, the rhenium on the resin is highly enriched, and then final elution is performed. The rhenium-rich solution is then sent to the evaporation and crystallization unit for crystallization. In other words, this application utilizes the adsorption column itself as a "concentrator," using an internal circulation adsorption-enrichment process of "adsorption, impurity removal, and elution" to continuously transport and concentrate rhenium from the dilute solution onto the resin, ultimately eluting out a high-concentration solution in one step. This completely eliminates the reliance on external high-energy-consuming evaporation and concentration equipment, requiring only gentle evaporation and crystallization of the final high-concentration solution. This significantly reduces energy consumption and floor space, and avoids rhenium loss during the evaporation process. Therefore, this application constructs a highly efficient, high-purity, energy-saving, and automated device suitable for the direct purification and preparation of high-purity ammonium perrylate from low-concentration rhenium solutions through the systematic operation of a resin pretreatment unit, an adsorption unit, a directional impurity removal unit, a segmented elution unit, a circulating enrichment unit, and an evaporation crystallization unit. This effectively solves the problems of low recovery efficiency, low product purity, and high energy consumption of existing rhenium extraction equipment.

[0035] 2. This application modularizes seven major functions: feeding, pretreatment, adsorption, impurity removal, elution, enrichment, and crystallization. These functions are tightly integrated through connecting pipelines, control units, and detection devices (such as liquid level sensors, bed height sensors, sampling valve groups, flow valves, metering pumps, heating belts, and other key execution and detection components). The control unit can automatically control the feeding speed, feeding start and stop (based on adsorption endpoint judgment), pretreatment process, metering and delivery of impurity removal and eluents, switching of eluent flow direction (to buffer tank or crystallization unit), start and stop of circulation enrichment, crystallization temperature, and vacuum degree, etc., according to preset programs and real-time feedback (such as liquid level, concentration, and temperature). This achieves full automation from feeding to crystallization, improves extraction and preparation efficiency and process stability, and reduces human operation errors and labor intensity.

[0036] 3. This application incorporates an electrically heated belt connected to a PLC on the outer wall of the adsorption column, precisely controlling the adsorption temperature within the optimal reaction range of 25~30℃. This improves the mass transfer efficiency of rhenium ions at low concentrations and the adsorption kinetics of the resin, further ensuring that rhenium ions can be efficiently and rapidly captured by the resin under low concentration (22~28 mg / L) conditions. This application fundamentally solves the problem of poor resin activity through a dedicated pretreatment structure, distributor, and constant temperature control, thereby improving the adsorption efficiency of low-concentration rhenium. 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 system architecture of the device provided in this application in one embodiment.

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

[0040] 1. Raw material liquid storage tank; 2. First valve; 3. Peristaltic pump; 4. Circular distributor; 5. First flow valve; 6. First metering valve; 7. Adsorption column; 8. Electric heating belt; 9. Sampling valve assembly; 10. Impurity removal agent storage tank; 11. Mixer; 12. Diaphragm pump; 13. Eluent storage tank; 14. Metering pump; 15. Eluent distribution valve; 16. Buffer tank; 17. Reflux pump; 18. Check valve; 19. Evaporation and crystallization unit. 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] The inventors conducted an in-depth analysis of the structural functions and shortcomings of existing equipment in practical applications, recognizing that: existing adsorption columns lack a dedicated water / regenerant inlet structure for resin pretreatment, relying solely on gravity backwashing. This results in uneven distribution of backwash water and regenerant, leading to uneven resin expansion (expansion rate fluctuation ±10%), resin activation rate <80%, and adsorption rate of low-concentration Re solutions (22~28 mg / L) <85%, failing to meet subsequent enrichment requirements. Furthermore, existing equipment lacks a dedicated impurity removal unit; the regenerant simultaneously washes away Re and impurities (SO4). 2- Bi 3+ The eluent contains impurities with a concentration >0.5 mg / L, resulting in low purity ammonium rheniumate obtained through subsequent crystallization, which is insufficient to meet industrial requirements. Furthermore, the existing equipment's eluent collection tank lacks a recirculation function, requiring an external evaporator for concentration of low-concentration eluent (Re < 200 mg / L), increasing equipment investment (evaporator cost accounts for 40% of total equipment cost) and energy consumption, and posing a risk of Re loss. Moreover, the existing equipment (adsorption column, storage tank, pump) is independently arranged, with complex piping connections (leakage rate > 3%), lacking a unified control module, requiring manual valve switching / parameter adjustment, resulting in low operating efficiency (single batch processing time > 8 hours).

[0045] To address this issue, the inventors have provided an apparatus for the pre-enrichment and segmented elution of high-purity ammonium perrylate from low-concentration rhenium-containing solutions using Tulsimer® RCX-5143 resin. This apparatus can directly purify and prepare high-purity ammonium perrylate from low-concentration rhenium solutions. The apparatus mainly includes: a control unit and, respectively, a feeding unit, a resin pretreatment unit, an adsorption unit, a directional impurity removal unit, a segmented elution unit, a circulating enrichment unit, and an evaporation crystallization unit, all communicatively connected to the control unit. The control unit can be a PLC control cabinet or an industrial computer. The following describes the apparatus in conjunction with... Figure 1 The structure and functional principles of each unit are explained in detail.

[0046] I. Feeding Unit

[0047] The feeding unit mainly includes a raw material storage tank 1, preferably made of 316L stainless steel, with a conical bottom (slope 1:10). The bottom outlet of the tank is connected sequentially to a first valve 2 and a peristaltic pump 3 (or a magnetically driven pump) via a corrosion-resistant pipe. The first valve can be a pneumatic valve with a PLC control signal interface to achieve automated control of valve opening and closing. As the outlet valve, the first valve is mainly responsible for starting, stopping, and roughly regulating the flow rate from the raw material storage tank to the peristaltic pump, while the peristaltic pump (with frequency conversion speed regulation, flow rate range 0~10 BV / h) is responsible for precise metering. Simultaneously, a first liquid level sensor and a breather valve are installed at the top of the tank. The first liquid level sensor monitors the liquid level in the raw material storage tank and communicates with the control unit. The outlet of the peristaltic pump is connected to the inlet of the adsorption column.

[0048] In this embodiment, the raw material storage tank stores pickling solution from copper smelting flue gas (rhenium concentration 22~28 mg / L). The liquid level signal is fed back to the PLC, which automatically controls the opening of the first valve to regulate the discharge rate from the raw material storage tank to the subsequent adsorption unit. For example, when the liquid level is lower than the reference level, the PLC may appropriately close the first valve to slow down the discharge rate, prevent the peristaltic pump from running dry, and allow time for replenishment. When the liquid level is normal or high, the first valve is opened to ensure a stable supply. The core purpose is to provide a stable and controllable raw material flow to the downstream adsorption unit.

[0049] In other embodiments, a pretreatment device, such as a filtration device, may be installed before the raw material storage tank.

[0050] II. Resin Pretreatment Unit

[0051] The resin pretreatment unit is used to regenerate the resin before or after each adsorption cycle, and is crucial for ensuring adsorption efficiency. The resin pretreatment unit mainly includes a dual-inlet water module, a ring distributor, and a bed height sensor located at the top of the adsorption column in the adsorption unit.

[0052] The dual-inlet water module includes a backwash deionization line and a regenerant line. The backwash deionization line includes a backwash deionized water pipe and a first flow valve 5 installed on the backwash deionized water pipe. The regenerant line includes a regenerant pipe and a first metering valve 6 installed on the regenerant pipe. The outlets of both the backwash deionization line and the regenerant line are connected to the inlet of the annular distributor 4.

[0053] The annular distributor 4 is a porous PP plate installed at the top inlet of the adsorption column 7. In this embodiment, 12 holes with a diameter of 2mm are evenly distributed along the circumference of the annular distributor. The annular distributor ensures that the backwash water / regenerant is evenly sprayed onto the resin bed.

[0054] The bed height sensor is used to monitor the bed height of the resin bed in the adsorption column, and the control unit monitors the resin expansion rate based on the data information obtained from the bed height sensor.

[0055] The resin pretreatment unit enables resin backwashing and expansion, as well as ammonium form activation. Backwashing and expansion involves introducing deionized water (flow rate 10 BV / h) into the backwashing deionization line, causing the resin bed to expand by 50%–60%. A bed height sensor sends a signal to the PLC, which then controls the first flow valve based on this signal. The purpose of backwashing and expansion is to loosen and clean the resin. Ammonium form activation involves introducing 5% NH4OH (flow rate 2–4 BV / h) into the regenerant line. The first metering valve delivers the regenerant according to the PLC settings, and the resin is evenly sprayed through a ring distributor, converting it to the ammonium form and ensuring subsequent adsorption capacity (activation rate >95%).

[0056] III. Adsorption Unit

[0057] The adsorption unit mainly consists of an adsorption column filled with a resin bed of Tulsimer® RCX-5143. The inlet of the annular distributor at the top of the adsorption column is connected to the outlet of a peristaltic pump. As the feed solution pumped by the peristaltic pump flows through the resin bed, rhenium is selectively adsorbed. The outlet at the bottom of the adsorption column is divided into two paths: one connects to a waste liquid collection tank (for storing adsorption waste liquid and impurity removal waste liquid), and the other connects to a staged elution unit.

[0058] The columnar shell of the adsorption column is made of borosilicate glass (acid-resistant, transparency ≥90%, inner diameter 25mm, effective height 1500mm), and the bottom of the columnar shell is provided with a double-layer sintered glass retention layer (pore size 10~20μm, to prevent resin loss). In other embodiments, the columnar shell of the adsorption column can also be made of polytetrafluoroethylene (PTFE) material, with a thickness of 8~10mm. It has comparable acid corrosion resistance and better impact resistance than glass, making it suitable for industrial environments with high vibration. Only the flange sealing gasket material needs to be adjusted to PTFE, without affecting other connections and functions.

[0059] To provide the optimal temperature environment for the adsorption process, an electric heating belt 8 is wound around the outside of the column (connected to the PLC, with a temperature control range of 25~30℃ to prevent low temperature from affecting adsorption and achieve efficient adsorption of low concentration Re).

[0060] Because the adsorption capacity of the resin in the adsorption column is limited, rhenium ions are adsorbed from top to bottom in the resin bed as the feed solution is continuously introduced. When the upper resin layer becomes saturated, the rhenium ions move downwards; this moving interface of the saturation zone is known in the industry as the "adsorption front." To monitor the adsorption front in real time, accurately determine the adsorption endpoint, and diagnose the internal working state of the adsorption column, this application provides five sampling ports (300mm apart, each equipped with a sampling valve group of 9, and featuring automatic sampling function with PLC control) along the height of the adsorption column.

[0061] Every time the adsorption column passes through twice the bed volume (2 BV) of feed liquid, the PLC-controlled sampling valve group automatically samples each layer. The obtained samples can be analyzed by an online analyzer to detect the rhenium concentration in the feed liquid exiting the adsorption column. In the initial stage of adsorption, the rhenium concentration in the feed liquid exiting the bottom of the adsorption column is extremely low because all the rhenium is captured by the resin. As adsorption progresses, the adsorption front gradually moves towards the bottom of the column. When the adsorption front reaches the bottom, the rhenium concentration in the effluent begins to rise sharply, at which point the resin is saturated. Therefore, by automatically sampling and monitoring the rhenium concentration in the effluent in real time, the adsorption endpoint can be accurately determined.

[0062] For example, a rhenium concentration threshold, such as 1 mg / L, can be set via PLC. When the rhenium concentration is detected to be <1 mg / L, it indicates that adsorption has not yet broken through and the adsorption column still has capacity, so the system continues to feed. When the rhenium concentration is detected to be ≥1 mg / L, the PLC immediately determines that adsorption has reached the endpoint and issues a command to shut down the peristaltic pump and the first valve, stopping the feeding.

[0063] Therefore, this application uses automatic sampling and monitoring to accurately determine the adsorption endpoint, avoiding the problems of insufficient feed leading to wasted resin capacity, and excessive feed causing saturated resin to be unable to adsorb rhenium, resulting in rhenium loss. Internal experiments have shown that this automatic sampling and monitoring design can ensure an adsorption rate >96%.

[0064] In addition, the layered sampling port design along the column height of this application can collect sample concentrations at the same time point from sampling ports at different heights. By comparison, a real-time movement curve of the "adsorption front" in the column can be plotted. This curve can be used to analyze resin performance and the uniformity of the distribution of the liquid in the resin, thereby providing data support for adjusting parameters such as feed flow rate and liquid concentration.

[0065] IV. Targeted Removal Unit

[0066] Once adsorption is complete and the feed solution is stopped from entering the adsorption column, the resin inside the column is saturated with rhenium ions (ReO4). - ) and impurity ions (such as SO4 ions) 2- Bi 3+ In this application, after the adsorption column completes adsorption, rhenium is not eluted directly. Instead, a depurifying agent is introduced into the adsorption column through a directional depurification unit to remove sulfate ions (SO4) adsorbed on the resin before elution. 2- ) and bismuth ions (Bi 3+ Impurities such as rhenium are removed, and the loss of rhenium during the directional impurity removal process is minimal and negligible.

[0067] The directional impurity removal unit includes a depurifying agent storage tank 10, a mixer 11, and a diaphragm pump 12 (with flow metering) connected in sequence. The depurifying agent storage tank is made of 316L material and stores a 1mol / L NaOH solution. A second level sensor can be installed inside the tank to enable automated replenishment. The diaphragm pump can also be a magnetically driven pump.

[0068] To ensure that the impurity remover can flow evenly through the entire resin bed and fully contact the resin, this application includes a mixer (with an internal stirring device) to uniformly mix the impurity remover and the carrier water flow. The purpose is to dilute the NaOH solution to a precise and effective concentration and ensure its uniform dispersion, avoiding impact or damage to the resin due to excessively high local NaOH concentration, while also ensuring the uniformity of the impurity removal effect.

[0069] During the directional impurity removal process, a diaphragm pump delivers the uniformly mixed impurity remover to the feed inlet at the top of the adsorption column at a flow rate set by the PLC (3 BV / h). In this process, the OH- in NaOH... - Ions will preferentially react with certain impurity ions (such as SO4) adsorbed on the resin. 2- Bi 3+ (It will form hydroxide precipitates or be replaced) undergo ion exchange or chemical reactions to "wash off" these impurities. The liquid flowing out from the bottom of the adsorption column is the impurity removal waste liquid containing a large number of impurities.

[0070] After the targeted removal of impurities, high-purity rhenium mainly remains on the resin in the adsorption column. Next, a high-concentration NH4OH solution (eluent) is used for elution to obtain a pure rhenium-rich solution.

[0071] V. Segmented Elution Unit

[0072] The segmented elution unit mainly includes an eluent storage tank 13, a metering pump 14 (flow rate range 0~5BV / h, accuracy ±0.05BV / h) and an eluent distribution valve 15 connected in sequence.

[0073] The eluent storage tank is made of 316L stainless steel and stores NH4OH solution (eluent). The tank is equipped with a constant temperature jacket (25~30℃).

[0074] The eluent distribution valve 15 has three outlet pipes: the first outlet pipe is connected to the inlet of the circulation enrichment unit, the second outlet pipe is connected to the inlet of the evaporation crystallization unit, and the third outlet pipe is connected to the waste liquid collection tank.

[0075] VI. Cyclic Enrichment Unit

[0076] The circulating enrichment unit includes a buffer tank 16, a reflux pump 17, and a one-way valve 18 connected in sequence. The buffer tank contains a third level sensor and a stirrer. The reflux pump is frequency-controlled and can be linked with a peristaltic pump to control the feed flow rate. The one-way valve prevents backflow of the feed liquid.

[0077] This application achieves segmented elution and enrichment through a segmented elution unit and a circulating enrichment unit. The first elution stage involves circulating a low-concentration eluent, using 3 mol / L NH4OH to elute rhenium adsorbed on the adsorption column resin. During this stage, the outlet of the eluent distribution valve switches to the circulating enrichment unit, and the resulting low-concentration rhenium solution (150~200 mg / L) is temporarily stored in a buffer tank. Then, circulating adsorption is performed, where the low-concentration rhenium solution in the buffer tank is mixed with the feed solution in the feed solution storage tank via a reflux pump and transported together (flow rate maintained at 5 BV / h), returning to the adsorption column for secondary adsorption and impurity removal, thus achieving the circulating enrichment of rhenium.

[0078] After completing the preset number of cycles or reaching the preset concentration (rhenium concentration > 2 g / L), the eluent distribution valve switches to the evaporation and crystallization unit.

[0079] In this application, the segmented elution and enrichment mainly utilize the high adsorption efficiency of the adsorption column for rhenium to re-enrich rhenium in dilute solutions onto the resin.

[0080] VII. Evaporation and Crystallization Unit

[0081] The evaporation crystallization unit 19 mainly includes a vacuum evaporation crystallization device made of 316L stainless steel, with a vacuum degree of -0.07 to -0.09 MPa and a heating area of ​​1~2 m². 2 It is equipped with an automatic unloading device and a purity monitoring interface (which can detect Re concentration and impurity content online). It can evaporate and crystallize rhenium-rich solution with a concentration >2g / L (temperature 80~85℃, time 3~4h) to obtain ammonium perrylate crystals with a purity >98.5%. The ammonium perrylate crystals are transported to the finished product storage tank for storage, while the crystallization mother liquor (Re <50mg / L) is returned to the raw material storage tank through the reflux valve set at the mother liquor outlet of the evaporation and crystallization device.

[0082] In other embodiments, the evaporation and crystallization unit can be a scraped thin-film evaporator, which occupies a smaller footprint (0.5~1m²). 2 The crystallization time is shortened to 2-3 hours, making it suitable for scenarios with large fluctuations in Re concentration.

[0083] The following explains the inlet and outlet connections of each unit.

[0084] The feed unit's raw material storage tank includes a raw material inlet (external feed), a bottom outlet, a circulating liquid inlet, and a mother liquor reflux outlet. The bottom outlet is connected sequentially to a first valve and a peristaltic pump via pipelines, ultimately leading to the top feed inlet of the adsorption column. The circulating liquid inlet is connected to the reflux pump outlet of the circulating enrichment unit to receive the low-concentration rhenium-rich solution used for secondary adsorption. The mother liquor reflux outlet is connected to the mother liquor outlet of the evaporation and crystallization unit to receive the mother liquor generated after crystallization.

[0085] The resin pretreatment unit includes a backwash water inlet, a regenerant inlet, and a bottom outlet. The backwash water inlet is connected to a deionized water source. The regenerant inlet is connected to a regenerant storage tank containing a 5% NH4OH solution. The bottom outlet is directly connected to the top opening of the adsorption column via a flange.

[0086] The top of the adsorption column in the adsorption unit forms a feed liquid inlet, a pretreatment liquid inlet, a decontamination agent inlet, an eluent inlet (these inlets can share a single feed port), and a bottom outlet. The feed liquid inlet connects to the outlet of the peristaltic pump to receive the feed liquid to be treated. The pretreatment liquid inlet is integrated from the bottom of the resin pretreatment unit and receives backwash water and regenerator. The decontamination agent inlet connects to the outlet of the diaphragm pump in the directional decontamination unit. The eluent inlet connects to the outlet of the metering pump in the segmented elution unit. An eluent distribution valve is installed at the bottom outlet. The first outlet of the eluent distribution valve connects to the inlet of the circulating enrichment unit, the second outlet connects to the inlet of the evaporation and crystallization unit, and the third outlet (waste liquid outlet) connects to the waste liquid collection tank, controlled by a valve. This outlet is used to discharge the waste liquid after adsorption or the waste liquid containing impurities after decontamination.

[0087] The inlet of the buffer tank of the circulating enrichment unit is connected to the first outlet of the eluent distribution valve, and the outlet of the reflux pump of the circulating enrichment unit is connected to the circulating liquid inlet of the feed unit.

[0088] The inlet of the evaporation crystallization unit is connected to the second outlet of the eluent distribution valve, the ammonium perrylate crystal outlet of the evaporation crystallization unit is connected to the finished product storage tank, and the mother liquor outlet is connected to the mother liquor reflux port of the feed unit.

[0089] The following is a detailed description of the process flow for the equipment provided in this application for directly purifying and preparing high-purity ammonium perrylate from low-concentration rhenium solutions.

[0090] This process is a closed-loop automated system integrating resin pretreatment, adsorption, directional impurity removal, staged elution, cyclic enrichment, and evaporation crystallization. It can efficiently and economically recover and prepare high-purity ammonium rheniumate from low-concentration rhenium solutions (Re 22~28 mg / L). The entire process is centrally controlled by a PLC (Programmable Logic Controller) to ensure accuracy, stability, and high efficiency. The process flow is described in stages below:

[0091] I. First Stage: Raw Material Transportation and Adsorption

[0092] 1. Raw material supply: The process begins in the raw material storage tank. This tank stores pickling solution (rhenium concentration 22~28 mg / L) from copper smelting flue gas. A level sensor inside the tank feeds the signal back to the PLC in real time.

[0093] 2. Precise feeding: The PLC controls the opening of the first valve (pneumatic valve) at the bottom of the raw material liquid storage tank according to the instructions, and links with the peristaltic pump (flow rate range 0~10BV / h) to deliver the raw material liquid to the adsorption column at a stable and controllable flow rate.

[0094] 3. High-efficiency adsorption and real-time monitoring:

[0095] Adsorption: The feed solution enters an adsorption column filled with Tulsimer® RCX-5143 resin and flows down through the resin bed. Rhenium ions are selectively adsorbed by the resin.

[0096] Temperature control: The heating band on the outer wall of the adsorption column maintains the temperature at 25~30℃ to ensure that the adsorption reaction is at the optimal temperature.

[0097] Monitoring: The adsorption column is equipped with 5 stratified sampling ports. The PLC controls automatic sampling after every 2 times the bed volume (2BV) of feed solution passes through, and monitors the concentration of rhenium in the outlet liquid in real time.

[0098] Endpoint determination: When the rhenium concentration in the outlet liquid is detected to be ≥1 mg / L, it indicates that the resin adsorption is close to saturation, and the PLC immediately orders the feeding to stop. At this stage, the rhenium adsorption rate is >96%. The adsorbed waste liquid is discharged to the waste liquid collection tank.

[0099] II. Second Stage: Resin Regeneration and Targeted Impurity Removal

[0100] This stage of resin pretreatment can be carried out periodically before or after adsorption to activate the resin.

[0101] 1. Resin backwashing: Deionized water (flow rate 10 BV / h) is introduced through the pretreatment unit at the top of the adsorption column to expand the resin bed by 50%~60%. The expansion rate is monitored by the bed height sensor. The purpose is to loosen the bed and remove the trapped solid impurities.

[0102] 2. Resin ammonium form activation: 5% NH4OH solution is introduced (flow rate 2~4 BV / h) and sprayed evenly through a ring distributor to convert the resin into a more active ammonium form, ensuring subsequent adsorption efficiency (activation rate >95%).

[0103] 3. Targeted impurity removal: After adsorption, the resin not only adsorbs rhenium but also contains impurities such as sulfate (SO4). 2- ), Bismuth ions (Bi 3+ Impurities such as rhenium and rhenium are removed. Therefore, the PLC starts the diaphragm pump, pumping a 1 mol / L NaOH solution (impurity remover) into the adsorption column at a flow rate of 3 BV / h from the top. As the NaOH solution flows through the resin bed, it preferentially reacts with the impurity ions, washing them off, while rhenium, due to its stronger binding force, remains on the resin. The waste liquid containing impurities flows out from the bottom of the column. This process achieves an impurity removal rate >98%, effectively separating rhenium from impurities.

[0104] III. Third Stage: Rhenium Elution and Cyclic Enrichment

[0105] 1. Segmented elution: A 3 mol / L NH4OH solution is used as the eluent to elute the adsorption column that has undergone impurity removal. First elution stage (low concentration stage): In the initial stage of elution, the eluent distribution valve is switched to the circulating enrichment unit. The rhenium concentration obtained in this stage is relatively low (150~200 mg / L).

[0106] 2. Circulating Enrichment: Low-concentration rhenium solution is temporarily stored in the buffer tank of the circulating enrichment unit. Subsequently, a PLC-controlled reflux pump transports this low-concentration rhenium solution back to the feed end of the adsorption column, where it mixes with the raw material solution for secondary adsorption. This "adsorption-removal-elution" cycle can be repeated until the rhenium concentration is enriched to >2 g / L. This design significantly increases the final eluent concentration, avoids dependence on external evaporation and concentration equipment, and significantly reduces energy consumption.

[0107] 3. High-concentration eluent production: When the eluent concentration is enriched to >2g / L, the eluent distribution valve switches from the circulation unit to the evaporation and crystallization unit, and sends the high-concentration rhenium-rich solution to the next stage.

[0108] IV. Fourth Stage: Crystallization and Mother Liquor Recovery

[0109] 1. Evaporation and crystallization: High-concentration rhenium-rich solution is evaporated in an evaporation and crystallization device at 80~85℃ and a vacuum degree of -0.07 to -0.09MPa to crystallize high-purity ammonium perrhenate crystals.

[0110] 2. Mother liquor recovery: After crystallization, the remaining mother liquor still contains a small amount of rhenium (Re<50mg / L). This mother liquor is returned to the raw material storage tank through a reflux valve for further recovery, forming a closed-loop resource system that maximizes the overall rhenium recovery rate and reduces waste liquid discharge.

[0111] Therefore, this application successfully achieves efficient and economical recovery of high-purity ammonium perrylate crystals from low-concentration solutions through a processing route of precision adsorption, directional impurity removal, internal circulation enrichment, and evaporation crystallization, combined with full-process PLC automatic control and online monitoring. The dual-inlet water supply and annular distributor structure of the resin pretreatment unit ensure uniform distribution of backwash water and regenerant, achieving a resin activation rate >95%, thus solving the core problem of low adsorption efficiency at low concentrations of Re. The linked structure of the buffer tank and reflux pump in the circulation enrichment unit, along with PLC-controlled synchronous speed adjustment of the reflux pump and the adsorption column feed pump, enables multiple circulation enrichment of the eluent, eliminating the need for expensive external concentration equipment and reducing energy consumption by 40%. The combination of a static mixer and a precision metering pump in the directional impurity removal unit ensures thorough mixing of the 1 mol / L NaOH solution with the feed solution, achieving an impurity removal rate >98% and guaranteeing the purity of ammonium perrylate. Layered sampling of the adsorption column and an electric heating belt enable automatic sampling and stable temperature control every 2 BV of feed solution, real-time monitoring of the adsorption process, and prevention of recovery rate loss due to Re leakage. Furthermore, during the manufacturing and application process, this equipment can be centrally controlled by an integrated framework and PLC, modularly integrating all units, achieving a pipeline leakage rate of <0.5%, increasing operational efficiency by 50%, and solving the problems of existing equipment being separate and complex to operate.

[0112] 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.

[0113] 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. An apparatus for directly purifying low-concentration rhenium solution to prepare high-purity ammonium rheniumate, characterized in that, It includes a control unit, and a feeding unit, a resin pretreatment unit, an adsorption unit, a directional impurity removal unit, a segmented elution unit, a circulating enrichment unit, and an evaporation crystallization unit, which are respectively communicatively connected to the control unit; The feeding unit includes a raw material liquid storage tank, and the bottom outlet of the raw material liquid storage tank is connected to the top inlet of the adsorption column through a first conveying pump. The resin pretreatment unit includes an annular distributor located at the top feed inlet of the adsorption column, a dual-channel water inlet module located at the inlet end of the annular distributor, and a bed height sensor located inside the adsorption column. The dual-channel water inlet module includes a backwash deionization pipeline and a regenerator pipeline. The adsorption unit includes the adsorption column, which is filled with a resin bed, and the bottom outlet of the adsorption column is provided with an eluent distribution valve. The directional impurity removal unit includes an impurity removal agent storage tank, a mixer, and a second delivery pump. The outlet end of the mixer is connected to the top inlet of the adsorption column. The segmented elution unit includes an eluent storage tank, a metering pump, and an eluent distribution valve. The outlet of the metering pump is connected to the inlet of the adsorption column. The eluent distribution valve has a waste liquid outlet, a first-stage eluent outlet, and a final circulating eluent outlet. The circulating enrichment unit includes a buffer tank, a reflux pump, and a check valve. The inlet of the buffer tank is connected to the outlet of the first stage eluent, and the outlet of the reflux pump is connected to the raw material storage tank. The evaporation crystallization unit includes a vacuum evaporation crystallization device, whose inlet is connected to the outlet of the final circulating eluent, and whose mother liquor outlet is connected to the raw material liquid storage tank.

2. The apparatus for directly purifying high-purity ammonium rhenium from a low-concentration rhenium solution according to claim 1, characterized in that, A first valve is provided on the pipeline between the bottom outlet of the raw material liquid storage tank and the first delivery pump; a first liquid level sensor and a breather valve are provided on the top of the raw material liquid storage tank. The first liquid level sensor is communicatively connected to the control unit, and the control unit is configured to adjust the opening of the first valve according to the signal of the first liquid level sensor to adjust the discharge rate. The raw material storage tank is also equipped with a raw material inlet, a circulating liquid inlet, and a mother liquor reflux outlet; the circulating liquid inlet is connected to the reflux pump outlet of the circulating enrichment unit to receive low-concentration rhenium-rich solution for secondary adsorption; the mother liquor reflux outlet is connected to the mother liquor outlet of the evaporation crystallization unit.

3. The apparatus for directly purifying high-purity ammonium perrylate from low-concentration rhenium solution according to claim 1, characterized in that, The annular distributor is a perforated plate with multiple through holes evenly distributed along its circumference. The inlet end of the backwash deionization pipeline is connected to a deionized water source, and a first flow valve is provided on the backwash deionization pipeline; a first metering valve is provided on the regenerant pipeline; the first flow valve, the first metering valve, and the bed height sensor are all communicatively connected to the control unit; the control unit is configured to control the first flow valve to operate according to the bed height signal obtained from the bed height sensor, thereby realizing the pretreatment of the resin.

4. The apparatus for directly purifying high-purity ammonium rhenium acid from low-concentration rhenium solution according to claim 1, characterized in that, The columnar shell of the adsorption column is made of borosilicate glass, and a double-layer sintered glass retention layer is provided at the bottom; an electric heating belt is wound around the outer wall of the adsorption column, and the electric heating belt is communicatively connected to the control unit to maintain the adsorption process temperature at 25~30℃. The adsorption column is provided with multiple sampling ports at equal intervals along its height direction. Each sampling port is connected to a sampling valve group. The sampling valve group is communicatively connected to the control unit. The control unit is configured to control each sampling valve group to automatically sample after passing through twice the bed volume of liquid, and to determine the adsorption endpoint of the resin based on the detected rhenium concentration.

5. The apparatus for directly purifying high-purity ammonium rhenium from a low-concentration rhenium solution according to claim 1, characterized in that, The impurity removal agent stored in the tank is a 1 mol / L NaOH solution, and a second liquid level sensor is installed in the tank. The mixer is equipped with a stirring device, and the mixer has an impurity removal agent inlet and a water inlet. The stirring device is used to uniformly mix the impurity removal agent with water.

6. The apparatus for directly purifying high-purity ammonium perrylate from low-concentration rhenium solution according to claim 1, characterized in that, The eluent storage tank stores NH4OH solution, and a constant temperature jacket is provided outside the eluent storage tank; the solution in the eluent storage tank is pumped to the top inlet of the adsorption column by the metering pump.

7. The apparatus for directly purifying high-purity ammonium rhenium acid from low-concentration rhenium solution according to claim 1, characterized in that, The buffer tank is equipped with a third liquid level sensor and a stirrer. The eluent distribution valve is communicatively connected to the control unit, which is configured to execute a segmented elution and cyclic enrichment control program, specifically including: After the directional impurity removal unit completes the removal of impurity ions from the resin, the metering pump is controlled to pump the eluent into the adsorption column, and the eluent distribution valve is controlled to switch its outlet to the first section eluent outlet. The low-concentration rhenium solution obtained from the first elution stage is collected into the buffer tank of the circulating enrichment unit; Subsequently, the reflux pump is controlled to pump the low-concentration rhenium solution in the buffer tank back to the raw material storage tank, mix it with the raw material solution, and then transport it back to the adsorption column for secondary adsorption through the first delivery pump. After completing a preset number of cycles or reaching a preset concentration, the eluent distribution valve is controlled to switch its outlet to the final circulating eluent outlet, and the rhenium-rich solution is transported to the evaporation and crystallization unit.

8. The apparatus for directly purifying low-concentration rhenium solution to prepare high-purity ammonium rheniumate according to claim 1, characterized in that, The mother liquor outlet of the vacuum evaporation crystallization device is equipped with a reflux valve for returning the crystallized mother liquor to the raw material storage tank.

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