An automatic control system and method for ion exchange for ammonium paratungstate preparation

Abstract

The present application relates to the technical field of tungsten hydrometallurgy, in particular to an ion exchange automatic control system and method for ammonium paratungstate preparation, comprising: a stage control module for switching the process stage of an ion exchange column and generating stage switching instructions; a segmented determination module for determining the segmented determination result of the desorption liquid according to the tungsten elution rate in the desorption stage; a switching verification module for determining the impurity index according to the conductivity detection value of the outlet of the ion exchange column and verifying the segmented determination result based on the impurity index to generate a verification result; and a switching execution module for switching the desorption liquid generated by the ion exchange column in the desorption stage to the corresponding storage tank of the determined segment according to the segmented switching instructions generated in response to the verification result and the segmented determination result. The present application improves the tungsten resource recycling rate.

Description

Technical Field

[0001] This invention relates to the field of tungsten hydrometallurgy, specifically to an automatic control system and method for the preparation of ammonium paratungstate. Background Technology

[0002] Ammonium paratungstate (APT) is an important intermediate product in the tungsten metallurgy industry. Ion exchange is currently the mainstream process for preparing APT from crude sodium tungstate solution due to its advantages such as short process, simple equipment, and high metal recovery rate. The ion exchange process operates in a cyclical manner, with each cycle consisting of five stages: adsorption, water washing, rinsing, desorption, and backwashing. Tungsten in the sodium tungstate solution is adsorbed by the resin, and after water washing and rinsing to remove impurities, it is eluted by a desorbent to obtain an ammonium tungstate solution. This solution is then evaporated and crystallized to obtain ammonium paratungstate.

[0003] During the desorption stage, the eluent is naturally segmented according to its composition: the initial eluent has a higher impurity content, the middle eluent has a high tungsten concentration and is sent to crystallization as the main product, and the final eluent has a low tungsten concentration and mainly contains residual desorbent. To improve tungsten recovery and reuse reagents, the eluent needs to be collected in segments during production.

[0004] However, existing segmented collection methods rely on manual, timed sampling and analysis of the tungsten concentration in the exudate, followed by manual valve switching based on experience. This process is time-consuming, with slow switching operations. Furthermore, using the instantaneous concentration of the exudate as the switching basis means that batch fluctuations in the feed concentration can cause the cutting position to drift. This can result in the higher impurity content of the initial stage liquid contaminating the main product liquid, or the higher tungsten concentration of the intermediate stage liquid being mistakenly switched into the reuse pipeline, leading to tungsten loss. Additionally, the switching operation lacks verification mechanisms, making it difficult to detect and intercept erroneous switching in a timely manner. Therefore, how to achieve automatic and accurate determination and switching of desorption liquid segments, avoiding product contamination and tungsten loss, and ensuring the targeted reuse of reagents are currently unresolved technical problems. Summary of the Invention

[0005] To address these issues, the present invention provides an automatic ion exchange control system and method for the preparation of ammonium paratungstate, which overcomes the problems in the prior art that fail to consider the impact of batch fluctuations in feed concentration on the accuracy of desorption liquid segmentation, cannot automatically determine the segment to which the desorption liquid belongs based on the degree of tungsten recovery and cannot verify the segmentation determination results, and cannot directionally switch each segment of desorption liquid to the corresponding storage tank, thus resulting in poor tungsten resource recovery and utilization.

[0006] To achieve the above objectives, in one aspect, the present invention provides an automatic ion exchange control system for the preparation of ammonium paratungstate, comprising: The stage control module is used to switch the process stage of the ion exchange column according to the order of adsorption, water washing, rinsing, desorption and backwashing, and generate stage switching instructions. The segmentation determination module is used to determine the tungsten elution rate during the desorption stage based on the detected tungsten concentration and instantaneous flow rate at the outlet of the ion exchange column. The module then compares the tungsten elution rate with a first preset tungsten elution threshold and a second preset tungsten elution threshold to determine the segment to which the desorbed liquid belongs, generating a segmentation determination result. The second preset tungsten elution threshold is greater than the first preset tungsten elution threshold. The segment includes a first-stage liquid, a second-stage liquid, and a third-stage liquid. The switching verification module is used to determine the impurity index based on the conductivity detection value of the outlet of the ion exchange column, and to verify the segmentation judgment result based on the impurity index to generate a verification result. The switching execution module, in response to the verification result that has passed, generates a segment switching command based on the segment determination result, and switches the desorption liquid generated by the ion exchange column in the desorption stage to the storage tank corresponding to the determined segment.

[0007] On the other hand, the present invention also provides a control method applicable to the above-mentioned automatic ion exchange control system for the preparation of ammonium paratungstate, comprising: The tungsten-containing liquid is passed into the ion exchange column, and the process stages are switched in the order of adsorption, water washing, rinsing, desorption and backwashing. During the desorption stage, the tungsten concentration and instantaneous flow rate at the outlet are measured to determine the tungsten elution rate. The tungsten elution rate is compared with a first preset tungsten elution threshold and a second preset tungsten elution threshold to determine the segmentation result of the desorption solution; wherein the second preset tungsten elution threshold is greater than the first preset tungsten elution threshold, and the segmentation includes a first-stage solution, a second-stage solution, and a third-stage solution; Obtain the conductivity value at the liquid outlet, determine the impurity index, and perform switching verification based on the segmentation judgment result and the impurity index; In response to successful verification, a segment switching command is generated to switch the desorbent to the storage tank corresponding to the segment determination result, so as to realize the recycling of the first segment liquid as a rinsing agent and the third segment liquid as a desorbent. In response to the end of the desorption phase, the ion exchange column is controlled to perform a backwashing phase so that the ion exchange column can enter the next adsorption phase.

[0008] By employing the above technical solution, this invention automatically switches the entire process cycle of ion exchange column according to the sequence of adsorption, water washing, rinsing, desorption, and backwashing. The tungsten elution rate, determined by the cumulative tungsten concentration at the outlet and the instantaneous flow rate, is used as a measure of the desorption process. The desorbed liquid is online classified into first-stage, second-stage, and third-stage liquids by comparing it with two preset tungsten elution thresholds. The segmentation results are quantitatively verified using an impurity index determined by conductivity. Only when the verification is successful is the switching execution module switched the desorbed liquid to the storage tank corresponding to the segment, thus realizing the automatic switching of the ion exchange process from adsorption to backwashing. The entire chain of feeding, segmentation, verification, and switching is unattended and automated. This transforms the segmented cutting process from manual observation of concentration based on experience to objective judgment based on the tungsten recovery ratio by the system. The verification process intercepts erroneous switching, thus ensuring accurate and stable cutting position and reliable product purity even when the concentration of the feed solution fluctuates from batch to batch. Furthermore, the first-stage solution is reused as a rinsing agent, and the third-stage solution is reused as a desorbent after replenishment. This reduces the consumption of fresh reagents, lowers waste liquid discharge, and improves the tungsten resource recovery rate, achieving continuous, automated, and green operation of the ammonium paratungstate preparation process.

[0009] This invention accumulates the eluted tungsten amount by combining the tungsten concentration detection value at the outlet and the instantaneous flow rate detection value at each sampling time according to the chronological order of sampling. The feed tungsten amount is determined by multiplying the cumulative feed flow rate and the feed tungsten concentration value during the adsorption stage, and the ratio of the two is taken as the tungsten elution rate. The cumulative amount of tungsten in the feed that has been eluted and recovered is used to measure the desorption process, so that the segmentation determination criteria no longer drift with batch fluctuations in feed concentration. Regardless of whether the feed is concentrated or diluted, the amount of residual tungsten in the resin corresponding to the same elution rate threshold remains consistent, and the segmentation cut-off point is stable and reproducible across different batches.

[0010] This invention achieves directional diversion of the desorbent according to the degree of tungsten recovery, ensuring that each component is properly positioned. This means that the low-tungsten-content first and third-stage desorbents are no longer discharged but directly reused in the production process. This reduces the consumption of fresh leaching and desorbent preparations, lowers wastewater discharge, and thus achieves the recycling of tungsten resources and reagents. Desorbents with a tungsten elution rate less than or equal to a first preset tungsten elution threshold are classified as first-stage desorbents and used as leaching agents in the next elution stage; those between the two thresholds are classified as second-stage desorbents and used for crystallization; and those exceeding a second preset tungsten elution threshold are classified as third-stage desorbents and, after supplementation with ammonium chloride, are used as desorbents in the next desorption stage. Attached Figure Description

[0011] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0012] Figure 1 This is a schematic diagram of the module connections of the automatic ion exchange control system for the preparation of ammonium paratungstate in an embodiment of the present invention; Figure 2This is a flowchart of a control method applicable to an automatic ion exchange control system for the preparation of ammonium paratungstate in an embodiment of the present invention. Detailed Implementation

[0013] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0014] Example 1: like Figure 1 As shown, in one aspect, the ion exchange automatic control system for the preparation of ammonium paratungstate according to an embodiment of the present invention includes: The stage control module is used to switch the process stage of the ion exchange column according to the order of adsorption, water washing, rinsing, desorption and backwashing, and generate stage switching instructions. The segmentation determination module is used to determine the tungsten elution rate during the desorption stage based on the detected tungsten concentration and instantaneous flow rate at the outlet of the ion exchange column. The module then compares the tungsten elution rate with a first preset tungsten elution threshold of 0.15 and a second preset tungsten elution threshold of 0.90 to determine the segment to which the desorbed liquid belongs, generating a segmentation determination result. The second preset tungsten elution threshold is greater than the first preset tungsten elution threshold. The segment includes a first-stage liquid, a second-stage liquid, and a third-stage liquid. The switching verification module is used to determine the impurity index based on the conductivity detection value of the outlet of the ion exchange column, and to verify the segmentation judgment result based on the impurity index to generate a verification result. The switching execution module, in response to the verification result that has passed, generates a segment switching command based on the segment determination result, and switches the desorption liquid generated by the ion exchange column in the desorption stage to the storage tank corresponding to the determined segment.

[0015] In this embodiment, the specific structure of the stage control module, segmentation judgment module, switching verification module and switching execution module is not limited. They themselves and each unit therein can be composed of logic components, including field-programmable components, computers or microprocessors in computers.

[0016] Specifically, the ion exchange column can be an exchange column filled with a strong basic anion exchange resin, such as 201×7 type resin; the outlet can be the outlet pipe at the bottom of the ion exchange column, and the outlet pipe can be equipped with an online tungsten concentration analyzer, conductivity meter, pH meter and flow meter; the tungsten concentration detection value is the concentration value of tungsten trioxide (WO3), which can be obtained by the online tungsten concentration analyzer at the outlet, or by sampling and testing at regular intervals; the desorbent can be a mixed solution of high-concentration ammonium chloride and ammonia water, such as 5 mol / L NH4Cl + 2 mol / L NH3·H2O; the desorbent liquid can be the effluent after the desorbent flows through the resin layer, which contains dissolved ammonium tungstate eluted from the resin; the storage tank can be an atmospheric pressure storage tank equipped with a level gauge located downstream of the ion exchange column.

[0017] It is understandable that the instantaneous tungsten concentration of the effluent only reflects the concentration of the liquid flowing out at that moment, and cannot reflect the amount of residual tungsten in the resin. When the tungsten concentration of the feed fluctuates from batch to batch, the amount of residual tungsten in the resin corresponding to the same instantaneous concentration threshold varies greatly, causing the cutting position to drift. The tungsten elution rate, however, is the ratio of the cumulative eluted tungsten to the feed tungsten, and regardless of the concentration of the feed, the amount of residual tungsten in the resin corresponding to the same tungsten elution rate remains consistent. For example, if the tungsten concentration of a certain batch of feed is low, the instantaneous concentration of the desorbed liquid will be generally low. If cutting is done according to the instantaneous concentration threshold, it may be mistakenly judged that the tungsten has been washed away and the process may be switched prematurely, resulting in tungsten residue on the resin. However, if cutting is done according to the tungsten elution rate, the cumulative ratio is not affected by the concentration of the feed, and the cutting position remains stable. Therefore, by using the tungsten elution rate as the basis for segmentation, the segmented cutting position can be prevented from drifting with batch fluctuations in the feed liquid, ensuring the accuracy of segmentation from a criterion perspective.

[0018] In some embodiments, the segmented determination module determines the tungsten elution rate as follows: based on the tungsten concentration detection value at the outlet and the instantaneous flow rate detection value at the outlet at each sampling time, the cumulative eluted tungsten amount is obtained according to the order of sampling times, wherein each sampling time is determined sequentially according to a preset sampling interval of 30s starting from the desorption stage; the feed tungsten amount is determined according to the product of the cumulative feed flow rate and the feed tungsten concentration value during the adsorption stage; the ratio of the cumulative eluted tungsten amount to the feed tungsten amount is calculated to obtain the tungsten elution rate.

[0019] Specifically, the cumulative amount of eluted tungsten ,in, The cumulative amount of eluted tungsten from the desorption stage up to the nth sampling time; i = 1, 2, 3, ..., n; n is the sequence number of the current sampling time, i.e., the nth sampling time has been collected, and the corresponding actual time is t = n × Δt; : The detected value of tungsten concentration at the outlet at the i-th sampling time; : Instantaneous flow rate at the outlet at the i-th sampling time; Δt: Preset sampling interval; Feed tungsten amount W0 = F × C0, where F is the cumulative feed flow rate during the adsorption stage, obtained by the flow meter on the feed pipeline, and C0 is the feed tungsten concentration value, which can be obtained by sampling and testing the feed batch or by detecting the tungsten concentration online analyzer on the feed pipeline; Tungsten elution rate R = W n / W0.

[0020] For example, if the cumulative feed flow rate during the adsorption stage of a certain batch is 10 m³ and the feed tungsten concentration is 200 g / L (calculated as tungsten trioxide), then the feed tungsten amount is 2000 kg. When desorption reaches the 100th sampling time, the cumulative eluted tungsten amount is 300 kg, then the tungsten elution rate R = 300 / 2000 = 0.15. The preset sampling interval can range from 10 s to 2 min; in this embodiment, it is set to 30 s to ensure that the number of sampling points in a single desorption stage is not less than 100, guaranteeing the accuracy of the cumulative calculation. Therefore, by accumulating the instantaneous concentration and instantaneous flow rate over time and then calculating the ratio, the tungsten elution rate can be obtained stably and reproducibly, unaffected by fluctuations in a single sampling.

[0021] As a preferred approach, the segment determination module determines the segment to which the desorbent belongs based on the tungsten elution rate. Specifically, if the tungsten elution rate is less than or equal to a first preset tungsten elution threshold of 0.15, the desorbent is determined to be a first-stage liquid, which is used to switch to the eluent storage tank for use as an eluent in the next elution stage. If the tungsten elution rate is greater than the first preset tungsten elution threshold and less than or equal to a second preset tungsten elution threshold of 0.90, the desorbent is determined to be a second-stage liquid, which is used to switch to a second-stage liquid storage tank for crystallization. If the tungsten elution rate is greater than the second preset tungsten elution threshold, the desorbent is determined to be a third-stage liquid, which is used to switch to the desorbent preparation tank. The third-stage liquid in the desorbent preparation tank is supplemented with ammonium chloride and used as the desorbent in the next desorption stage.

[0022] The first preset tungsten elution threshold can range from 0.10 to 0.20, and in this embodiment, it is set to 0.15; the second preset tungsten elution threshold can range from 0.85 to 0.95, and in this embodiment, it is set to 0.90. It is understood that the effluent in the initial stage of desorption mainly consists of residual eluent from the column and the ejected impurity segment. At this stage, the cumulative eluted tungsten amount is a very low proportion of the feed tungsten amount. The first preset tungsten elution threshold is used to distinguish this impurity segment from the tungsten-rich second-stage effluent. When the elution ratio exceeds 0.90, there is very little remaining tungsten on the resin, and the effluent enters the tailing segment, which is mainly composed of residual desorbent. The second preset tungsten elution threshold is used to distinguish the second-stage effluent from this tailing segment, so that each segment flows to the corresponding storage tank according to its tungsten content and impurity state. Therefore, by directing the desorbent flow according to the degree of tungsten recovery, the first-stage effluent is reused as eluent, and the third-stage effluent is reused as desorbent, reducing the consumption of fresh reagents, lowering waste discharge, and achieving the recycling of tungsten resources and reagents.

[0023] The switching verification module verifies the segment judgment results based on the impurity index, where the impurity index is the ratio of the outlet conductivity detection value to the preset conductivity threshold. If the segment judgment result is a single-stage or three-stage liquid and the impurity index is greater than the preset impurity index, a verification result of passing is generated. If the segment judgment result is a two-stage liquid and the impurity index is less than or equal to the preset impurity index of 1.0, a verification result of passing is generated. Otherwise, a verification result of failing is generated, the switching execution module suspends the generation of segment switching commands and outputs a verification alarm.

[0024] In one possible implementation, the preset conductivity threshold can be the upper limit of the measured conductivity of the ammonium tungstate solution prepared according to the ammonium tungstate concentration of the second-stage solution; the preset impurity index can be in the range of 1.0-1.2, and in this embodiment, it is set to 1.0. It is understood that the impurity index is in the form of a ratio. When it is 1.0, the verification boundary coincides with the threshold boundary, and when it is greater than 1.0, a margin can be reserved for instrument measurement error. The first-stage solution contains rinsing residue and impurities, and the third-stage solution is mainly composed of high-concentration ammonium chloride desorbent. The conductivity of both is significantly higher than that of the ammonium tungstate solution in the second-stage solution. Therefore, the impurity index of the first-stage and third-stage solutions should be greater than 1, and the impurity index of the second-stage solution should be less than or equal to 1. If the judgment result contradicts the conductivity characterization, for example, if it is judged as a second-stage solution but the impurity index is greater than 1, it indicates that the tungsten concentration detection is abnormal or the judgment is incorrect. Therefore, by performing a differential verification of the segmentation judgment results in opposite directions based on conductivity, erroneous switching can be intercepted, impurities can be prevented from entering the crystallization raw material liquid, and the purity of the product liquid can be guaranteed.

[0025] Preferably, the switching execution module generates segmented switching instructions, and also responds when the differential pressure detection value of the ion exchange column is less than or equal to a preset differential pressure threshold. The preset differential pressure threshold can range from 0.1 MPa to 0.2 MPa, and in this embodiment, it is set to 0.15 MPa. It is understood that the column pressure drop during the normal batch desorption stage generally does not exceed 0.1 MPa. The preset differential pressure threshold is set to 1.5 times the upper limit of the normal pressure drop to promptly pause the switching when the resin layer becomes fouled or caked, avoiding cross-contamination caused by forced switching when the flow channel inside the column is abnormal.

[0026] In addition, an anomaly attribution module is included to determine the cause of an anomaly when the desorption process meets preset anomaly conditions. Preset anomaly conditions include: the tungsten elution rate is less than the first preset tungsten elution threshold for a preset time of 30 minutes, or the tungsten concentration at the outlet of the second-stage solution, as determined by the segmentation judgment module, is less than the preset lower concentration limit of 80 g / L. The preset time can range from 20 min to 60 min; in this embodiment, it is 30 min. It is understood that in a normal batch, it takes 10 min to 15 min for the tungsten elution rate to rise to the first preset tungsten elution threshold. The preset time is twice this time to trigger anomaly attribution when the desorption process is significantly slower than the normal process. The preset lower concentration limit can range from 50 g / L to 100 g / L (calculated as tungsten trioxide); in this embodiment, it is 80 g / L. It is understood that the tungsten concentration of the second-stage solution in a normal batch is generally higher than 100 g / L, and a value below 80 g / L indicates significantly insufficient desorption intensity. When preset abnormal conditions are met, the abnormal attribution module obtains the pH value detected at the outlet and calculates the desorbent deviation. The desorbent deviation is the absolute value of the difference between the pH detection value and the preset pH value. The preset pH value ranges from 8.5 to 9.5; in this embodiment, the preset pH value is 9.0. The preset deviation threshold can be 0.2.

[0027] It is understandable that ammonia is used to maintain the NH4+ / NH3 buffer system in the desorbent. If the pH is too low, there will be insufficient free ammonia and the desorption driving force will decrease. If the pH is too high, the ammonia consumption of the subsequent crystallization mother liquor will increase. The preset deviation threshold of 0.2 is consistent with the control precision of 9.0±0.2 in the process specification. If the desorbent deviation is greater than the preset deviation threshold of 0.2, the abnormality is determined to be due to an abnormal desorbent ratio. Specifically, if the pH detection value is greater than the preset pH value of 9.0, an adjustment instruction to reduce the ammonia replenishment flow rate is generated; if the pH detection value is less than the preset pH value, an adjustment instruction to increase the ammonia replenishment flow rate is generated. If the desorbent deviation is less than or equal to the preset deviation threshold, the abnormality is determined to be due to an abnormal resin state, and a resin state check alarm is output.

[0028] Specifically, the decrease in ammonia replenishment flow rate is positively correlated with the difference between the pH detection value and the preset pH value, and the increase is positively correlated with the difference between the preset pH value and the pH detection value. For example, when the pH detection value is greater than the preset pH value, the difference between the pH detection value and the preset pH value is recorded as ΔpH, and the decrease in ammonia replenishment flow rate ΔF = k × ΔpH; when the pH detection value is less than the preset pH value, the difference between the preset pH value and the pH detection value is recorded as ΔpH, and the increase in ammonia replenishment flow rate ΔF = k × ΔpH; where k is the flow rate adjustment coefficient, and in this embodiment, k is taken as 5% of the ammonia replenishment flow rate for every 0.1 pH unit.

[0029] For example, when the pH value is 9.3, ΔpH = 9.3 - 9.0 = 0.3, and the decrease ΔF = k × 0.3, that is, the decrease is 15% of the ammonia water replenishment flow rate; when the pH value is 8.8, ΔpH = 9.0 - 8.8 = 0.2, and the increase ΔF = k × 0.2, that is, the increase is 10% of the ammonia water replenishment flow rate.

[0030] Understandably, if the desorbent ratio is normal but tungsten still cannot be eluted, the problem lies with the resin. By first addressing the abnormality in the partition ratio and the resin itself, targeted measures can be taken to avoid blindly shutting down the system when the cause is unclear. The adjustment amount is positively correlated with the deviation; large deviations can be quickly corrected, while small deviations can be finely adjusted.

[0031] In this embodiment, the system further includes an ion exchange module and a segmented liquid storage module. The ion exchange module includes two parallel ion exchange columns, used to perform adsorption, water washing, rinsing, desorption, and backwashing under the control of the stage control module. Each ion exchange column is equipped with an online tungsten concentration analyzer, conductivity meter, pH meter, and flow meter on its outlet pipeline, used to detect the tungsten concentration, conductivity, pH value, and instantaneous flow rate at the outlet, respectively. A differential pressure transmitter is installed between the inlet and outlet of the column to detect the pressure difference of the ion exchange column. The detection signals of the above-mentioned instruments are all connected to the DCS so that each functional module can obtain the corresponding detection values. A regulating valve is installed on the ammonia water replenishment pipeline of the desorbent preparation tank to regulate the ammonia water replenishment flow rate. The system also includes an operator station to output alarm information to the operator. The signal output terminals of the stage control module are connected to the electric regulating valves and pneumatic switching valves of each process pipeline to control the alternating operation of the two ion exchange columns. Specifically, in response to the adsorption breakthrough of one ion exchange column, a stage switching command is generated to start the other ion exchange column into the adsorption stage. The segmented liquid storage module includes an eluent storage tank, a secondary liquid storage tank, and a desorbent preparation tank. The signal output terminal of the switching execution module is connected to the outlet switching valve group to switch the outlet liquid from the ion exchange column during the desorption stage to one of the eluent storage tank, the secondary liquid storage tank, or the desorbent preparation tank.

[0032] Specifically, the signal output terminal of the stage control module is connected to the signal input terminal of the segment judgment module to send the stage switching command to the segment judgment module, so that the segment judgment module starts sampling and cumulative calculation when the ion exchange column enters the desorption stage; the signal output terminal of the segment judgment module is connected to the signal input terminals of the switching verification module, the stage control module, and the anomaly attribution module respectively, to send the segment judgment result to the switching verification module, and send the tungsten elution rate to the stage control module and the anomaly attribution module, so that the stage control module can determine the end time of the desorption stage and the anomaly attribution module can determine whether the desorption process meets the preset anomaly conditions; the signal output terminal of the switching verification module is connected to the signal input terminal of the switching execution module to send the verification result to the switching execution module; the signal output terminal of the anomaly attribution module is connected to the regulating valve on the ammonia water replenishment pipeline of the desorbent preparation tank to send the regulating command to the regulating valve, and the signal output terminal of the anomaly attribution module is also connected to the operator station to output a resin status check alarm; the signal output terminal of the switching execution module is also connected to the operator station to output a verification alarm when the verification fails.

[0033] Example 2: On the other hand, such as Figure 2 As shown, the embodiment of the present invention applies to the control method of the above-mentioned automatic ion exchange control system for the preparation of ammonium paratungstate, including: A crude sodium tungstate solution obtained from grinding and alkaline decomposition of tungsten ore was used as the tungsten-containing feed solution. This solution was fed into an ion exchange column at a flow rate of 8-12 m³ / h for adsorption. An online tungsten concentration analyzer was used to monitor the tungsten concentration in the post-exchange solution in real time. When the tungsten concentration at the outlet was greater than 0.5 g / L (as WO3), the ion exchange column was considered to have achieved adsorption breakthrough, and the column was switched to the water washing stage. Deionized water was then fed in at a flow rate of 5-8 m³ / h for washing. When the conductivity at the outlet was less than or equal to 200 μS / cm, the column was switched to the rinsing stage. A section of the solution collected during the desorption stage was used as the rinsing agent, and rinsing was performed at a controlled linear velocity of 0.02-0.04 m / min to thoroughly remove impurities such as phosphorus, arsenic, silicon, and tin adsorbed on the resin.

[0034] After 90 minutes of rinsing, desorbent is introduced into the ion exchange column to begin the desorption stage. From the start of the desorption stage, the tungsten concentration and instantaneous flow rate at the outlet are sequentially acquired at 30-second sampling intervals. The cumulative eluted tungsten amount is calculated, and the feed tungsten amount is determined by multiplying the cumulative feed flow rate and feed tungsten concentration during the adsorption stage. The ratio of the cumulative eluted tungsten amount to the feed tungsten amount is calculated to obtain the tungsten elution rate. The tungsten elution rate is compared with a first preset tungsten elution threshold of 15% and a second preset tungsten elution threshold of 90%. If the tungsten elution rate is less than or equal to 15%, the desorbed solution is determined to be a first-stage solution; if the tungsten elution rate is greater than 15% and less than or equal to 90%, the desorbed solution is determined to be a second-stage solution; if the tungsten elution rate is greater than 90%, the desorbed solution is determined to be a third-stage solution, generating a segmented determination result. Simultaneously, the conductivity value at the outlet is acquired, the ratio of the conductivity value to the preset conductivity threshold is calculated to obtain the impurity index, and a switching verification is performed based on the segment judgment result and the impurity index: if the segment judgment result is a single-stage liquid or a three-stage liquid and the impurity index is greater than 1.0, the verification passes; if the segment judgment result is a two-stage liquid and the impurity index is less than or equal to 1.0, the verification passes; otherwise, the verification fails, the generation of segment switching instructions is paused, and a verification alarm is output. In response to successful verification and a differential pressure reading of less than or equal to 0.15 MPa on the ion exchange column, a segment switching command is generated to switch the desorbent to the storage tank corresponding to the segment determination result: the first-stage solution is switched to the eluent storage tank for use as the eluent in the next eluent stage; the second-stage solution is switched to the second-stage solution storage tank for crystallization; and the third-stage solution is switched to the desorbent preparation tank, where ammonium chloride is added, for example, to a concentration of 5 mol / L, before being used as the desorbent in the next desorption stage, thus achieving the recycling of the first-stage solution as the eluent and the third-stage solution as the desorbent.

[0035] When the tungsten elution rate is greater than 90% and the tungsten concentration at the outlet is less than or equal to 0.1 g / L (as WO3), the desorption stage is considered to be over, and the ion exchange column is controlled to perform the backwash stage: backwash water is introduced from the bottom of the column and run at the set flow rate for 30 minutes to loosen the resin and remove suspended solids; after the backwash is completed, the liquid level is automatically lowered, and the ion exchange column enters the next adsorption stage and enters the next operating cycle.

[0036] Specifically, the process of controlling an ion exchange column to complete one operating cycle is explained: Adsorption stage: Sodium tungstate solution is passed into the ion exchange column at a flow rate of 8-12 m³ / h. When the tungsten concentration at the outlet exceeds the preset breakthrough threshold, adsorption breakthrough is determined, and a stage switching command to switch to the water washing stage is generated. The preset breakthrough threshold can be in the range of 0.3 g / L-1.0 g / L (calculated as tungsten trioxide). In this embodiment, the value is 0.5 g / L, which is consistent with the control index of the upper limit of tungsten content allowed in the post-exchange liquid in the ion exchange process specification. It is understood that if the upper limit is too high, tungsten will be lost with the wastewater, and if it is too low, the resin will not be fully utilized and will need to be switched to regeneration.

[0037] Water washing stage: Deionized water is introduced at a flow rate of 5m³ / h-8m³ / h. In response to the conductivity detection value at the outlet being less than or equal to the preset water washing endpoint conductivity, a stage switching command is generated to switch to the rinsing stage. The preset water washing endpoint conductivity can be in the range of 100μS / cm-500μS / cm. In this embodiment, the value is 200μS / cm, which is consistent with the control index of the process specification. It can be understood that the conductivity of deionized water is generally lower than 10μS / cm. After flowing through the resin layer, it rises due to the dissolution of residual salts. A value of 200μS / cm indicates that the soluble salts on the resin surface are basically washed away.

[0038] Rinsing stage: A single-stage liquid is used as the rinsing agent, and the linear velocity is controlled at 0.02m / min-0.04m / min to deeply remove impurities such as phosphorus, arsenic, silicon, and tin adsorbed on the resin. In response to the rinsing time reaching the preset rinsing time, the stage control module generates a stage switching command to switch to the desorption stage. The preset rinsing time can be in the range of 60min-120min, and in this embodiment, it is set to 90min. It can be understood that the purpose of rinsing is to remove impurities deeply, and its progress is determined by the cumulative volume of the rinsing agent flowing through the resin layer. Controlling the time by a fixed duration can ensure that the degree of impurity removal is consistent for each batch.

[0039] Desorption stage: Segmentation judgment, verification, switching, and anomaly attribution are performed; in response to the tungsten elution rate being greater than the second preset tungsten elution threshold and the tungsten concentration detection value at the outlet being less than or equal to the preset endpoint concentration, a stage switching command to end the desorption stage is generated; the preset endpoint concentration can be in the range of 0.05 g / L-0.2 g / L (calculated as tungsten trioxide), and in this embodiment, it is set to 0.1 g / L, which is consistent with the control index of the desorption endpoint in the process specification; it can be understood that if the tungsten concentration at the outlet is less than 0.1 g / L, it indicates that the tungsten that can be desorbed on the resin has been basically washed away, and the benefit of continuing desorption is less than the consumption of desorbent and working time.

[0040] Backwashing Stage: After desorption, the resin bed becomes compacted due to long-term operation, and suspended solids and broken resin particles accumulate within it, requiring backwashing for removal. During backwashing, backwash water is introduced from the bottom of the ion exchange column, flowing upwards through the resin bed, causing it to expand and fluidize. Suspended solids and smaller broken resin particles adhering to the resin surface are discharged from the top of the column with the backwash water. The backwash flow rate is determined based on the expansion rate of the resin bed, controlled within the range of 50%-100%; in this embodiment, 60% is used. This ensures sufficient loosening of the resin bed to release compacted areas while preventing excessive expansion that could lead to the loss of normal resin particles with the backwash water. The backwashing time ranges from 15 min to 60 min; in this embodiment, 30 min is used. After backwashing, the ion exchange column enters the next adsorption stage, beginning the next operating cycle.

[0041] By adopting the system of this embodiment, the first and third stages of liquid are reused in a targeted manner, reducing the consumption of fresh leaching agent and desorbent, reducing waste liquid discharge, and improving the recycling rate of tungsten resources.

[0042] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An automatic ion exchange control system for the preparation of ammonium paratungstate, characterized in that, include: The stage control module is used to switch the process stage of the ion exchange column according to the order of adsorption, water washing, rinsing, desorption and backwashing, and generate stage switching instructions. The segmentation determination module is used to determine the tungsten elution rate during the desorption stage based on the detected tungsten concentration and instantaneous flow rate at the outlet of the ion exchange column. The module then compares the tungsten elution rate with a first preset tungsten elution threshold and a second preset tungsten elution threshold to determine the segment to which the desorbed liquid belongs, generating a segmentation determination result. The second preset tungsten elution threshold is greater than the first preset tungsten elution threshold. The segment includes a first-stage liquid, a second-stage liquid, and a third-stage liquid. The switching verification module is used to determine the impurity index based on the conductivity detection value of the outlet of the ion exchange column, and to verify the segmentation judgment result based on the impurity index to generate a verification result. The switching execution module, in response to the verification result that has passed, generates a segment switching command based on the segment determination result, and switches the desorption liquid generated by the ion exchange column in the desorption stage to the storage tank corresponding to the determined segment.

2. The automatic ion exchange control system for the preparation of ammonium paratungstate according to claim 1, characterized in that, The segmentation determination module determines the tungsten elution rate, wherein... The segmented determination module calculates the cumulative eluted tungsten amount based on the tungsten concentration detection value at the outlet of the ion exchange column and the instantaneous flow rate detection value at the outlet of the ion exchange column at each sampling time, according to the chronological order of sampling time; wherein, each sampling time is a time determined sequentially according to a preset sampling interval starting from the self-desorption stage. The segmentation determination module determines the amount of tungsten to be fed based on the product of the cumulative feed flow rate and the feed tungsten concentration value of the ion exchange column during the adsorption stage. The segmented determination module calculates the ratio of the cumulative eluted tungsten amount to the feed tungsten amount to obtain the tungsten elution rate.

3. The automatic ion exchange control system for the preparation of ammonium paratungstate according to claim 2, characterized in that, The segment determination module determines the segment to which the desorption solution belongs based on the tungsten elution rate, wherein, If the tungsten elution rate is less than or equal to the first preset tungsten elution threshold, the segment determination module determines that the desorption liquid is a first-stage liquid. The first-stage liquid is used to switch to the eluent storage tank for use as an eluent in the next elution stage. If the tungsten elution rate is greater than the first preset tungsten elution threshold and less than or equal to the second preset tungsten elution threshold, the segmentation determination module determines that the desorption liquid is a second-stage liquid, and the second-stage liquid is used to switch to the second-stage liquid storage tank for crystallization. If the tungsten elution rate is greater than the second preset tungsten elution threshold, the segment determination module determines that the desorption liquid is a three-stage liquid. The three-stage liquid is used to switch to the desorbent preparation tank. The three-stage liquid in the desorbent preparation tank is supplemented with ammonium chloride and then used as the desorbent for the next desorption stage.

4. The automatic ion exchange control system for the preparation of ammonium paratungstate according to claim 3, characterized in that, The switching verification module verifies the segmentation judgment result based on the impurity index, wherein... The impurity index is the ratio of the detected conductivity value at the outlet of the ion exchange column to a preset conductivity threshold. If the segmentation determination result is a single-segment liquid or a three-segment liquid, and the impurity index is greater than the preset impurity index, then the switching verification module generates a verification result indicating that the verification has passed. If the segmentation determination result is a two-stage liquid and the impurity index is less than or equal to the preset impurity index, then the switching verification module generates a verification result indicating that the verification has passed. Otherwise, the switching verification module generates a verification result indicating that the verification failed, and the switching execution module suspends the generation of segmented switching instructions and outputs a verification alarm.

5. The automatic ion exchange control system for the preparation of ammonium paratungstate according to claim 4, characterized in that, The switching execution module generates segmented switching instructions and also responds when the differential pressure detection value of the ion exchange column is less than or equal to a preset differential pressure threshold.

6. The automatic ion exchange control system for the preparation of ammonium paratungstate according to claim 3, characterized in that, It also includes an anomaly attribution module, which is used to determine the cause of an anomaly when the desorption process meets preset anomaly conditions, wherein... The preset abnormal conditions include: the tungsten elution rate is less than the first preset tungsten elution threshold within a preset time period, or the segmentation determination module determines that the tungsten concentration detection value at the outlet of the second-stage liquid is less than the preset lower limit of concentration. The anomaly attribution module obtains the pH detection value at the outlet of the ion exchange column and calculates the desorbent deviation, which is the absolute value of the difference between the pH detection value and the preset pH value. If the desorbent deviation is greater than a preset deviation threshold, the anomaly attribution module determines the cause of the anomaly to be an abnormal desorbent ratio. If the pH detection value is greater than the preset pH value, the anomaly attribution module generates an adjustment command to reduce the ammonia replenishment flow rate; If the pH detection value is less than the preset pH value, the anomaly attribution module generates an adjustment command to increase the ammonia replenishment flow rate; If the desorbent deviation is less than or equal to a preset deviation threshold, the anomaly attribution module determines the cause of the anomaly as an abnormal resin condition and outputs a resin condition check alarm.

7. The automatic ion exchange control system for the preparation of ammonium paratungstate according to claim 6, characterized in that, The decrease in the ammonia replenishment flow rate is positively correlated with the difference between the pH detection value and the preset pH value; the increase in the ammonia replenishment flow rate is positively correlated with the difference between the preset pH value and the pH detection value.

8. The automatic ion exchange control system for the preparation of ammonium paratungstate according to claim 3, characterized in that, The stage control module generates a stage switching command to end the desorption stage, in response to the tungsten elution rate being greater than the second preset tungsten elution threshold and the tungsten concentration detection value at the outlet of the ion exchange column being less than or equal to the preset endpoint concentration. During the adsorption stage, the stage control module responds to the tungsten concentration detection value at the outlet of the ion exchange column being greater than the preset penetration threshold, determines that the ion exchange column has undergone adsorption penetration, and generates a stage switching command to switch the adsorbed and penetrated ion exchange column to the water washing stage. During the water washing stage, the stage control module generates a stage switching command to switch the ion exchange column to the rinsing stage in response to the detection value of the outlet conductivity of the ion exchange column being less than or equal to the preset water washing endpoint conductivity.

9. The automatic ion exchange control system for the preparation of ammonium paratungstate according to claim 8, characterized in that, It also includes an ion exchange module and a segmented liquid storage module: The ion exchange module includes ion exchange columns arranged in parallel, which are used to perform adsorption, water washing, rinsing, desorption and backwashing under the control of the stage control module. The stage control module is used to control the parallel ion exchange columns to operate alternately. In response to the adsorption and breakthrough of one group of ion exchange columns, the stage control module generates a stage switching command to start another group of ion exchange columns to enter the adsorption stage. The segmented liquid storage module includes the eluent storage tank, the second-stage liquid storage tank, and the desorbent preparation tank; the switching execution module is used to switch the effluent from the ion exchange column during the desorption stage to one of the eluent storage tank, the second-stage liquid storage tank, or the desorbent preparation tank.

10. A control method applicable to the automatic ion exchange control system for the preparation of ammonium paratungstate according to any one of claims 1-9, characterized in that, include: The tungsten-containing liquid is passed into the ion exchange column, and the process stages are switched in the order of adsorption, water washing, rinsing, desorption and backwashing. During the desorption stage, the tungsten concentration and instantaneous flow rate at the outlet are measured to determine the tungsten elution rate. The tungsten elution rate is compared with a first preset tungsten elution threshold and a second preset tungsten elution threshold to determine the segmentation result of the desorption solution; wherein the second preset tungsten elution threshold is greater than the first preset tungsten elution threshold, and the segmentation includes a first-stage solution, a second-stage solution, and a third-stage solution; Obtain the conductivity value at the liquid outlet, determine the impurity index, and perform switching verification based on the segmentation judgment result and the impurity index; In response to successful verification, a segment switching command is generated to switch the desorbent to the storage tank corresponding to the segment determination result, so as to realize the recycling of the first segment liquid as a rinsing agent and the third segment liquid as a desorbent. In response to the end of the desorption phase, the ion exchange column is controlled to perform a backwashing phase so that the ion exchange column can enter the next adsorption phase.

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