Bauxite lithium extraction dynamic optimization system based on adsorption process feedback

Abstract

The present application relates to the technical field of industrial lithium extraction, and particularly relates to a bauxite lithium extraction dynamic optimization system based on adsorption process feedback, which comprises a real-time monitoring module for continuously collecting relevant operating parameters of the adsorption process, a performance estimation module for determining the operating standard range of the current adsorption operating parameters according to historical adsorption operating parameters, a hierarchical decision module for determining the performance characterization trend of the adsorption system according to the adsorption breakthrough time, and a dynamic execution module for determining the optimization measures according to the deterioration reason of the adsorption performance. Based on the determination result of the overall performance deterioration, the hierarchical decision module determines the deterioration reason of the adsorption performance according to the adsorption bed pressure drop and the suspended matter removal rate, or determines the deterioration reason of the adsorption performance in combination with the analysis of the peak concentration and the analysis time. The system takes adsorption as the core, simplifies the dynamic optimization process through real-time monitoring, hierarchical diagnosis and precise control measures, and also takes into account the improvement of lithium extraction efficiency and cost control.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial lithium extraction, and particularly relates to an alumina ore lithium extraction dynamic optimization system based on adsorption process feedback. BACKGROUND

[0002] Alumina is the core raw material for extracting aluminum metal worldwide, and its smelting process produces a large amount of high-salt lithium-containing waste liquid with complex components. In addition to containing lithium ions, it also contains impurity ions such as calcium, magnesium, boron, and suspended particulate matter. If directly discharged, it will not only pollute water resources, but also waste lithium, a strategic scarce resource. The demand for lithium as a core material for power batteries, energy storage devices, and other materials continues to grow, and traditional lithium resource mining has been difficult to fully meet market supply. Recycling lithium resources from industrial waste liquid has gradually become an important way to make up for the shortage of lithium resources, and has dual significance of resource recycling and environmental protection. As a core means of selective enrichment of lithium resources, adsorption technology occupies an irreplaceable position in this field.

[0003] The adsorption unit is a key core link in the process of extracting lithium from alumina smelting waste liquid, and its performance directly determines the efficiency and quality of the entire lithium extraction process. Due to the similar physical and chemical properties of lithium ions and impurity ions in the waste liquid, and the lithium concentration being much lower than the impurity ion concentration, if there is a lack of efficient adsorption separation step, the subsequent concentration and purification unit will face great processing pressure. Not only will it cause membrane module fouling and resin pollution due to too many impurities, greatly reducing the service life of the equipment, but also will seriously affect the purity of lithium products. High-quality adsorption technology can capture lithium ions through selective adsorbents (such as phosphoric acid-based composite resins, chelating resins, etc.), achieving preliminary and efficient separation of lithium from impurities such as calcium, magnesium, and sodium. This not only provides high-quality feed for subsequent weak acid cation exchange bed, membrane concentration, and deep impurity removal units, reducing energy consumption and reagent consumption of subsequent processes, but also significantly improves lithium recovery rate, and is the technical basis for realizing the resource utilization of low-concentration lithium-containing waste liquid. However, traditional adsorption technology has problems such as insufficient selectivity of adsorbents, low adsorption capacity, easy contamination by suspended solids, and low desorption efficiency, which makes it difficult to break through 80% lithium recovery rate, and poor stability of adsorption and desorption cycles, which becomes a core bottleneck restricting the large-scale application of alumina lithium extraction technology.

[0004] With the increasing demand for high-end products such as battery-grade lithium carbonate in the industry, and the deepening of the concept of clean production, the existing lithium extraction process has been difficult to meet the comprehensive requirements of high recovery rate, high purity, low energy consumption and full component recovery. On the one hand, the technical shortcomings of the adsorption unit directly affect the synergy of the overall process. The matching degree of adsorption and pretreatment, desorption in the traditional process is insufficient, which leads to the rapid pollution of adsorbent, high regeneration frequency, and increases the operation cost. On the other hand, most processes only focus on the single extraction of lithium, ignoring the recovery of sodium, boron and other resources in the waste liquid after adsorption and the recycling of water resources, resulting in secondary resource waste. In this case, the core role of strengthening adsorption technology is to optimize the selection of adsorbent, improve the supporting role of pretreatment to the adsorption unit, perfect the adsorption and desorption cycle process, and build a collaborative system of adsorption and subsequent units, which is the key to breaking through the bottleneck of bauxite lithium extraction technology. At the same time, the adsorption unit needs to be integrated with multiple unit processes to achieve efficient enrichment of lithium resources, deep removal of impurities, synchronous recovery of multiple component resources and recycling of water resources, and promote the transformation of the bauxite smelting industry to a resource recycling and green low-carbon development model.

[0005] Chinese Patent Publication No. CN115784503B discloses a system and method for extracting lithium from salt lake brine and preparing battery-grade lithium carbonate. The system includes a coagulation and sedimentation system, a filtration system, an adsorption and desorption system, a calcium and magnesium removal system, a boron removal system, a concentration system, an evaporation system, and a lithium precipitation system connected in sequence. The calcium and magnesium removal system includes a primary reverse osmosis concentration unit, a primary nanofiltration calcium and magnesium removal unit, a secondary reverse osmosis concentration unit, a multi-stage nanofiltration calcium and magnesium removal unit, and a calcium and magnesium ion exchange unit connected in sequence. The boron removal system includes a primary nanofiltration boron removal unit, a multi-stage nanofiltration boron removal unit, and a boron ion exchange unit connected in sequence. The lithium precipitation system further includes a precision filtration system and a water washing and drying system connected in sequence. The process improves lithium recovery rate and produces battery-grade lithium carbonate, greatly improving resource utilization and recovery rate of the lithium extraction system, reducing water consumption and sodium carbonate consumption during the lithium precipitation system processing. Therefore, the existing technology has the following problems:

[0006] The existing technology has low intelligence level and lacks real-time monitoring and dynamic optimization capability for core units such as adsorption, resulting in unstable adsorption performance, high membrane pollution risk, and heavy ion exchange load, which further increases equipment investment and operation cost. SUMMARY

[0007] To this end, the application provides an alumina-based lithium extraction dynamic optimization system based on adsorption process feedback to overcome the above technical problems, which takes adsorption as the core, simplifies the dynamic optimization process through real-time monitoring, hierarchical diagnosis and precise control measures, stabilizes the adsorption performance and reduces membrane pollution and resin load, while adapting to raw material fluctuations and taking into account efficiency improvement and cost control.

[0008] To achieve the above-mentioned purpose, the application provides an alumina-based lithium extraction dynamic optimization system based on adsorption process feedback, which is applied to the following lithium extraction process: after pretreatment, the waste liquid is introduced into the adsorption device for selective adsorption of lithium, and after adsorption saturation, the desorption liquid is introduced for desorption to obtain lithium-rich liquid, the dynamic optimization system comprises:

[0009] a real-time monitoring module for continuously collecting relevant operating parameters of the adsorption process, the relevant operating parameters at least including adsorption breakthrough time and adsorption bed pressure drop of the adsorption stage, desorption peak concentration and desorption time of the desorption stage, and suspended solids removal rate of the pretreatment stage;

[0010] a performance estimation module for determining the operating standard range of the current adsorption operating parameters according to historical adsorption operating parameters, the adsorption operating parameters including adsorption temperature, feed pH value and desorption liquid concentration;

[0011] a hierarchical decision module for determining the performance characterization trend of the adsorption system according to the adsorption breakthrough time;

[0012] and, based on the determination result of the overall performance deterioration, determining the deterioration reason of the adsorption performance according to the adsorption bed pressure drop and the suspended solids removal rate, or determining the deterioration reason of the adsorption performance in combination with the desorption peak concentration and the desorption time;

[0013] wherein, the deterioration reason includes adsorption pollution leading to adsorption bed blockage, low adsorption kinetic efficiency and low desorption kinetic efficiency;

[0014] a dynamic execution module for determining optimization measures according to the deterioration reason of the adsorption performance, including optimizing the waste liquid pretreatment process and adjusting the adsorption operating parameters of the adsorption device.

[0015] As a preferred technical solution of the alumina-based lithium extraction dynamic optimization system based on adsorption process feedback, the hierarchical decision module calculates the shortening amplitude of the adsorption breakthrough time to determine the performance characterization trend of the adsorption device according to the adsorption breakthrough time, including:

[0016] determining the performance characterization trend of the adsorption device as normal overall performance and maintaining the current adsorption operating parameters according to the determination result that the shortening amplitude is less than the preset amplitude;

[0017] According to the determination result that the shortening amplitude is greater than or equal to a preset amplitude, it is determined that the performance characterization trend of the adsorption device is overall performance degradation, and a diagnosis process of a degradation cause is triggered.

[0018] As a preferred technical solution of the bauxite lithium extraction dynamic optimization system based on adsorption process feedback, the hierarchical decision module determines the degradation cause of the adsorption performance according to the pressure drop change rate calculated based on the adsorption bed pressure drop and in combination with the suspended solids removal rate based on the determination result of the overall performance degradation, wherein:

[0019] According to the determination result that the pressure drop change rate and the suspended solids removal rate satisfy the physical degradation condition, it is determined that the degradation cause of the adsorption performance is adsorption pollution leading to adsorption bed blockage.

[0020] The physical degradation condition is that the pressure drop change rate is greater than or equal to a preset change rate and the suspended solids removal rate is less than or equal to a preset removal rate.

[0021] As a preferred technical solution of the bauxite lithium extraction dynamic optimization system based on adsorption process feedback, the hierarchical decision module determines the degradation cause of the adsorption performance in combination with the desorption peak concentration and the desorption time according to the determination result that the pressure drop change rate and the suspended solids removal rate do not satisfy the physical degradation condition.

[0022] As a preferred technical solution of the bauxite lithium extraction dynamic optimization system based on adsorption process feedback, the hierarchical decision module calculates a concentration change rate and a time length change rate according to the desorption peak concentration and the desorption time respectively, and determines whether the degradation cause of the adsorption performance is low adsorption kinetic efficiency according to the concentration change rate, comprising:

[0023] According to the determination result that the concentration change rate is greater than or equal to a concentration change rate threshold, it is determined that the degradation cause of the adsorption performance is low adsorption kinetic efficiency.

[0024] On the contrary, it is determined whether the degradation cause of the adsorption performance is low desorption kinetic efficiency in combination with the time length change rate.

[0025] As a preferred technical solution of the bauxite lithium extraction dynamic optimization system based on adsorption process feedback, the dynamic execution module determines a method for optimizing the waste liquid pretreatment process according to the suspended solids removal rate in response to the degradation cause of the adsorption performance being adsorption pollution leading to adsorption bed blockage, wherein:

[0026] In response to the suspended solids removal rate being less than a benchmark removal rate, an adsorbent online cleaning program is started;

[0027] In response to the suspended solids removal rate being greater than or equal to the benchmark removal rate, the filtration accuracy of the pretreatment unit is increased;

[0028] The reference removal rate is less than a preset removal rate.

[0029] As the preferred technical scheme of the bauxite lithium extraction dynamic optimization system based on adsorption process feedback, the dynamic execution module determines the optimization measure as adjusting the adsorption flow rate and the adsorption temperature to the corresponding operation standard values in response to the low adsorption kinetics efficiency as the cause of the deterioration of the adsorption performance.

[0030] As the preferred technical scheme of the bauxite lithium extraction dynamic optimization system based on adsorption process feedback, the dynamic execution module determines the optimization measure according to the real-time elution liquid concentration in response to the low elution kinetics efficiency as the cause of the deterioration of the adsorption performance.

[0031] According to the real-time elution liquid concentration being at or above the corresponding concentration operation range, the optimization measure is determined as reducing the flow rate of the elution liquid flowing through the adsorption device.

[0032] The concentration operation range is greater than the corresponding concentration operation standard range.

[0033] As the preferred technical scheme of the bauxite lithium extraction dynamic optimization system based on adsorption process feedback, the dynamic execution module determines the optimization measure according to the real-time elution liquid concentration in response to the low elution kinetics efficiency as the cause of the deterioration of the adsorption performance.

[0034] According to the real-time elution liquid concentration being below the corresponding concentration operation range, the optimization measure is determined as adjusting the elution liquid concentration to the corresponding concentration operation standard range.

[0035] Compared with the prior art, the bauxite lithium extraction dynamic optimization system based on adsorption process feedback provided by the application relies on the real-time monitoring module to capture key operation parameters of adsorption and elution, and combines the reasonable operation standard range established by the performance estimation module to provide data support for hierarchical decision-making, accurately determines the system performance trend and the deterioration sources such as adsorption bed blockage and insufficient kinetics efficiency, and the dynamic execution module takes targeted optimization measures accordingly, optimizes the pretreatment process and adjusts the operation parameters, effectively guarantees the stability and continuity of the lithium extraction process, improves the synergy of the adsorption and elution links, reduces invalid operations and resource consumption, enhances the adaptation ability of the system to complex working conditions, and helps efficient and orderly promotion of the lithium extraction process and realizes precise control of the lithium extraction process.

[0036] Especially, the hierarchical decision module realizes accurate control of the running state of the adsorption device and efficient positioning of the deterioration cause by constructing layer-by-layer progressive decision logic and multi-parameter linkage analysis mechanism. The module takes the parameters in the stable performance period as the benchmark, quantifies the running parameter fluctuation by calculating the standard change rate to distinguish between normal performance fluctuation and overall performance deterioration state of the adsorption device, avoids misjudgment caused by abnormal single parameter, prevents excessive frequent triggering of the diagnosis process to increase the running burden, and avoids the continuous development of performance deterioration to cause a chain problem. After performance deterioration is determined, the bed layer blockage caused by adsorption pollution is accurately identified by the combined determination of the pressure drop change rate and the suspended matter removal rate, and non-pollution factor interference is excluded. For non-physical deterioration scenarios, the core difference between low adsorption kinetics efficiency and low desorption kinetics efficiency is clarified by analyzing the change rate of the peak concentration and the desorption time, and potential problems such as adsorbent performance degradation are prompted, forming a comprehensive deterioration cause diagnosis system, providing a clear optimization direction for the dynamic execution module, avoiding blind measures, ensuring stable and efficient operation of the adsorption process, reducing resource consumption and subsequent processing pressure, and improving the overall reliability and adaptability of the lithium extraction process.

[0037] Especially, the dynamic execution module responds according to the bed layer blockage caused by adsorption pollution according to the suspended matter removal rate, and when the pretreatment unit is slightly failed, online cleaning is preferred to quickly restore the adsorption performance at low cost; when the pretreatment unit is seriously failed, the filter precision is upgraded to block impurities from the source and prevent the adsorbent from being continuously contaminated; for the deterioration cause of low adsorption kinetics efficiency, the adsorption flow rate and temperature are directly adjusted to standard values, the physical contact conditions and thermodynamic environment are optimized, and the adsorption reaction rate is fundamentally improved; for the deterioration cause of low desorption kinetics efficiency, the desorption liquid flow rate is reduced when the concentration is in a reasonable range, the desorption efficiency is improved by prolonging the mass transfer time; only when the concentration is too low, the concentration is adjusted to minimize chemical reagent consumption and process fluctuation; the stability and continuity of the adsorption and desorption process are ensured, the resource utilization efficiency is significantly improved, the operation cost and equipment wear are reduced, and the self-adaptability of the system to complex working conditions is enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The connection diagram of the bauxite lithium extraction dynamic optimization system based on adsorption process feedback in the embodiment of the application;

[0039] Figure 2 The workflow diagram of the hierarchical decision module in the embodiment of the application;

[0040] Figure 3 The workflow diagram of the dynamic execution module in the embodiment of the application. DETAILED DESCRIPTION

[0041] In order to make the objects and advantages of the present application more clear, the present application will be further described below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are merely used to explain the present application and should not be used to limit the present application.

[0042] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood by those skilled in the art that the embodiments are merely used to explain the technical principles of the present application and should not be used to limit the protection scope of the present application.

[0043] It should be noted that, in the description of the present application, the terms indicating the direction or positional relationship such as "upper", "lower", "left", "right", "inner", "outer" and the like are based on the direction or positional relationship shown in the drawings, which is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0044] In addition, it should also be noted that, in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0045] It should be understood that the process flow of extracting lithium element from bauxite generally includes three flow lines, namely lithium extraction line, by-product line and water recycling line, wherein:

[0046] 1. The process flow of the lithium extraction line is generally as follows: waste liquid → buffer tank → first metal membrane filtration → adsorption device (lithium extraction) → elution liquid → coarse filtration → first online micro-flocculation and first ultrafiltration → weak acid cation bed → primary membrane concentration → secondary membrane concentration → chelating resin → boron removal device → first evaporation device → precipitation tank (add sodium carbonate) → lithium carbonate product;

[0047] 2. After the precipitation of lithium carbonate, the mother liquor mainly contains unreacted sodium nitrate (NaNO3), a small amount of lithium salt and trace impurities, i.e. high-salt lithium-containing lean liquid, which needs to recover sodium nitrate through the by-product recovery line, and the process flow is mainly as follows: high-salt lithium-containing lean liquid → second metal membrane filtration → second evaporation device → crystallization device → sodium nitrate product;

[0048] 3. The main body of the waste liquid discharged after the adsorption of the adsorption device contains a small amount of lithium, but contains a large amount of sodium salt, alkali and a small amount of other impurities, which needs to be recycled and utilized through the water recycling line, and the process flow is mainly as follows: lithium-containing lean liquid → second online micro-flocculation and second ultrafiltration → reverse osmosis device → circulating water;

[0049] In addition, after the boron removal device is saturated, the resin needs to be regenerated by using acid or hot water, and a high-concentration boron-containing elution solution is generated, which needs to be further treated (including adjusting pH, evaporative crystallization or preparing boric acid) to realize the recycling of boron elements and avoid the accumulation of harmful substances.

[0050] It can be understood that the selective adsorption and elution of lithium is the core of the entire lithium extraction process, which determines the lithium recovery rate and preliminary purity. However, in the existing process, this unit lacks real-time monitoring and dynamic control mechanism, is easily affected by the fluctuations in pretreatment effect and changes in raw material composition, and has problems such as accelerated adsorbent pollution, shortened breakthrough time, and incomplete elution, which not only reduces the lithium recovery rate and stability, but also increases the processing load of subsequent units, increases operation and maintenance costs and reagent consumption. Therefore, the present application dynamically adjusts the adsorption and elution process to break through the process bottleneck, ensure product purity, and improve overall efficiency.

[0051] Please refer to Figure 1 The connection diagram of the bauxite lithium extraction dynamic optimization system based on adsorption process feedback provided by the embodiments of the present application is shown in FIG. 1. The embodiments of the present application provide a bauxite lithium extraction dynamic optimization system based on adsorption process feedback, which is applied to a production line for recovering lithium carbonate from waste liquid generated in the extraction of aluminum from bauxite. The production line at least includes sequentially connected adsorption devices, elution liquid storage tanks, membrane concentration devices, and sedimentation tanks. The lithium extraction process of the adsorption device includes selectively adsorbing lithium by passing the pretreated waste liquid into the adsorption device, and obtaining a lithium-rich liquid by passing the elution liquid into the adsorption device after adsorption saturation.

[0052] The dynamic optimization system provided by the embodiments of the present application includes a real-time monitoring module for continuously collecting relevant operating parameters of the adsorption process, a performance estimation module, a hierarchical decision-making module connected to the real-time monitoring module, and a dynamic execution module connected to the real-time monitoring module, the performance estimation module, and the hierarchical decision-making module, respectively.

[0053] In the implementation, an online lithium ion concentration monitor is installed on the outlet pipe of the adsorption device to continuously monitor the lithium ion concentration in the solution at the outlet of the adsorption device from the beginning of the adsorption process, and when the monitored lithium ion concentration reaches the breakthrough concentration (usually 5%-10% of the influent concentration), the time point is recorded, and the time interval from the beginning of the adsorption to this time point is recorded as the adsorption breakthrough time; pressure sensors or differential pressure transmitters are installed on the inlet pipe and outlet pipe of the adsorption device to continuously monitor the real-time pressures at the inlet and outlet of the adsorption device, and the difference between the inlet pressure Pin and the outlet pressure Pout is calculated, which is the adsorption bed pressure drop ΔP, i.e. ΔP = Pin - Pout; an online lithium ion concentration monitor is installed on the outlet pipe through which the eluate flows out of the adsorption device to continuously monitor the lithium ion concentration in the eluate from the beginning of the elution process, and the highest value of the monitored lithium ion concentration during the entire elution process is recorded as the elution peak concentration, the time from the beginning of the elution to the time point at which the elution peak concentration is monitored is recorded as the elution peak time, and the time from the beginning of the elution to the time point at which the monitored lithium ion concentration drops to 5% or 10% of the peak concentration is recorded as the total elution time. In the present application, the kinetic efficiency of the elution process is determined by the elution time, and the time to reach the peak directly reflects the speed of the elution speed, so the elution time in the present application refers to the time to reach the peak.

[0054] In the implementation, the suspended solids concentration is determined by bypass sampling or installation of online monitoring equipment at the influent and effluent of the pretreatment unit to calculate the suspended solids removal rate.

[0055] The performance estimation module determines the operating standard range of the current adsorption operating parameters based on historical adsorption operating parameters, including adsorption temperature, influent pH value, and eluate concentration.

[0056] In the implementation, historical adsorption operating parameters during stable operation of the adsorption device in the past 6 months are collected, and the data points are ensured to be not less than 100 groups. If not enough, the time is expanded to nearly 12 months. Effective data groups with lithium recovery rate ≥ 90% and product lithium carbonate purity ≥ 99.5% are screened out, and after removing outliers in the effective data groups using the 3σ principle, the average value μ and the standard deviation σ of the adsorption temperature, the influent pH value, and the eluate concentration are calculated. The average value is set as the center, and ±2σ is set as the operating standard range of the current adsorption operating parameters.

[0057] It can be understood that the historical adsorption operating parameters need to be reanalyzed and the operating standard range needs to be updated every month to every quarter.

[0058] It should be understood that the adsorption breakthrough time refers to the time for lithium ions in the feed liquid to flow from the inlet of the adsorption device to the outlet and reach a preset threshold value of lithium ion concentration, which directly reflects the effective enrichment capacity of the adsorption device for lithium ions. When the performance of the adsorption device is stable, the combination efficiency of lithium ions and the adsorbent and the mass transfer state of the bed layer are at a balanced level, and the breakthrough time remains stable. Once the performance of the device decreases, the adsorbent cannot effectively intercept lithium ions, and the breakthrough phenomenon occurs earlier, i.e., the breakthrough time is shortened.

[0059] Please refer to Figure 2 The working flow chart of the hierarchical decision module of the embodiment of the present application is shown in the figure. The hierarchical decision module calculates the shortening range of the adsorption breakthrough time according to the adsorption breakthrough time to determine the performance trend of the adsorption device, including:

[0060] According to the determination result that the shortening range is less than the preset range, it is determined that the performance trend of the adsorption device is normal overall performance and the current adsorption operation parameters are maintained. It can be understood that the current performance attenuation is within an acceptable normal fluctuation range, and the core factors such as adsorbent activity and pretreatment effect have not changed significantly, and maintaining the current parameters can ensure the stability of the process;

[0061] According to the determination result that the shortening range is greater than or equal to the preset range, it is determined that the performance trend of the adsorption device is overall performance degradation and a diagnosis process of the degradation cause is triggered. It can be understood that the significant shortening of the adsorption breakthrough time has exceeded the normal fluctuation range, which may be accompanied by problems such as adsorbent contamination and process parameter deviation from the optimal value. If not timely diagnosed and intervened, it will lead to a chain reaction such as decrease of lithium recovery rate and increase of load of subsequent membrane concentration unit, and the diagnosis process needs to be used to locate the degradation cause and make targeted optimization.

[0062] In implementation, the shortening range = (average adsorption breakthrough time of the adsorption device in the performance stable period - real-time adsorption breakthrough time in the current operation period) ÷ average adsorption breakthrough time of the adsorption device in the performance stable period × 100%, and the performance stable period usually refers to 1 month continuously after the last system debugging is completed. The preset range usually has a value of 10% to 20%. The adsorption breakthrough time has normal fluctuations due to slight changes in raw material composition and small deviations in operation parameters. If the preset range is too small, the system will frequently trigger the diagnosis process, increasing energy consumption and operation complexity. If it is too large, it may lead to continuous deterioration of performance, causing adsorbent contamination, significant decrease of lithium recovery rate and increase of subsequent processing cost. Based on historical operation data statistics, when the shortening range of the adsorption breakthrough time reaches 10% to 15%, it is usually caused by reversible factors (including too fast adsorption flow rate and temperature fluctuation). Preferably, the preset range is 15%.

[0063] The hierarchical decision module calculates a pressure drop change rate based on the determination result of the overall performance degradation, according to the pressure drop of the adsorption bed, the pressure drop change rate = (real-time adsorption bed pressure drop in the current operation cycle - average adsorption bed pressure drop of the adsorption device in the performance stable period) ÷ average adsorption bed pressure drop of the adsorption device in the performance stable period × 100%, to determine the degradation reason of the adsorption performance in combination with the suspended solids removal rate, wherein:

[0064] According to the determination result that the pressure drop change rate and the suspended solids removal rate meet the physical degradation condition, it is determined that the degradation reason of the adsorption performance is that the adsorption pollution causes the adsorption bed to be blocked.

[0065] The physical degradation condition is that the pressure drop change rate is greater than or equal to a preset change rate and the suspended solids removal rate is less than or equal to a preset removal rate.

[0066] It can be understood that the core role of the pretreatment unit is to remove suspended particles, colloids and other impurities in the waste liquid. If the suspended solids removal rate decreases, the impurities that are not removed will enter the adsorption device with the feed, deposit on the surface of the adsorbent or block the adsorbent pores, and the accumulation of impurities in the adsorption bed will reduce the bed voidage and increase the fluid flow resistance, which directly manifests as an increase in the adsorption bed pressure drop. A single increase in pressure drop may be caused by factors such as fluctuations in feed flow, uneven adsorbent packing, and non-pollution factors, so simultaneous determination of the increase in pressure drop and the decrease in suspended solids removal rate can conclusively determine whether the cause of the degradation of the adsorption performance is that the adsorption pollution causes the adsorption bed to be blocked.

[0067] In implementation, the preset change rate is usually 20% to 50%, which is less than 20% and is easily affected by normal process fluctuations to cause misjudgment, and is more than 50% and may have caused serious pollution of the adsorbent, which will increase the difficulty of cleaning and lithium loss, and is preferably 30%; the preset removal rate is usually 85% to 95%, which is less than 85% (i.e., the suspended solids breakthrough rate > 15%) and represents that the pretreatment unit is severely ineffective, and impurities have entered the adsorption unit in large quantities, which significantly increases the risk of pollution, and is preferably 90%, which is the lower limit of stable operation of an industrial pretreatment unit.

[0068] Specifically, the hierarchical decision module performs the following operations when determining the degradation reason of the adsorption performance according to the determination result that the pressure drop change rate and the suspended solids removal rate do not meet the physical degradation condition, in combination with the resolved peak concentration and the resolution time:

[0069] a concentration change rate and a time length change rate are calculated according to the resolved peak concentration and the resolved time, respectively; in implementation, the concentration change rate is (an average resolved peak concentration of the adsorbent performance stable period - a real-time resolved peak concentration in the current running period) ÷ the average resolved peak concentration of the adsorbent performance stable period × 100%, and the time length change rate is (a real-time resolved time in the current running period - an average resolved time of the adsorbent performance stable period) ÷ the average resolved time of the adsorbent performance stable period × 100%;

[0070] whether the degradation cause of the adsorption performance is low adsorption kinetics efficiency is determined according to the concentration change rate, including:

[0071] the degradation cause of the adsorption performance is determined to be low adsorption kinetics efficiency according to a result of determining that the concentration change rate is greater than or equal to a concentration change rate threshold value; it can be understood that the resolved peak concentration is the maximum concentration of lithium ions in a unit volume of resolved liquid, and directly depends on the desorption rate of lithium ions from the surface of the adsorbent; the concentration change rate ≥ the concentration change rate threshold value indicates that the difficulty of desorption of lithium ions from the active sites of the adsorbent increases, that is, the combination of lithium ions and the adsorbent is too strong (low adsorption kinetics efficiency) in the adsorption process, resulting in difficulty in rapid desorption during resolution;

[0072] on the contrary, whether the degradation cause of the adsorption performance is low resolution kinetics efficiency is determined in combination with the time length change rate; in implementation, if the time length change rate ≥ a time length change rate threshold value, it is determined that the degradation cause is low resolution kinetics efficiency; if the time length change rate is less than the time length change rate threshold value, it is determined that the degradation cause is not low resolution kinetics efficiency, which may be adsorbent performance attenuation, and the adsorbent should be regenerated to restore its activity; if the performance cannot be restored after regeneration, the adsorbent should be replaced. It can be understood that the resolved time depends on the mass transfer rate and desorption reaction rate of the resolved liquid and the adsorbent; the time length change rate ≥ the time length change rate threshold value indicates that the rate of the entire resolution process is slow, which is that the resolution kinetics efficiency is low due to improper setting of parameters such as concentration, temperature and flow rate of the resolved liquid, resulting in a decrease in mass transfer or reaction rate;

[0073] in implementation, the values of the concentration change rate threshold value and the time length change rate threshold value are determined based on the kinetic characteristics of the resolution process and process requirements; generally, the concentration change rate threshold value has a value range of 15% to 30%, and preferably 20%; generally, the time length change rate threshold value has a value range of 20% to 40%, and preferably 25%.

[0074] specifically, the dynamic execution module determines a method for optimizing the waste liquid pretreatment process according to the suspended matter removal rate in response to the degradation cause of the adsorption performance being that adsorption pollution causes the adsorption bed to be blocked.

[0075] In response to the suspended matter removal rate being less than the reference removal rate, an adsorbent online cleaning program is started; it can be understood that when the suspended matter removal rate is greater than or equal to the reference removal rate, the pretreatment unit is slightly failed, the impurity breakthrough amount is small, and the adsorbent pollution is mainly surface deposition, at this time, the adsorbent online cleaning program is preferentially started, the suspended matter on the surface of the adsorbent is removed through chemical or physical methods, and the adsorption performance is quickly restored, and the cost is lower than that of replacing the pretreatment filter element; in implementation, the adsorbent online cleaning program refers to a combined operation of backwashing, chemical cleaning and forward washing to remove the pollutants on the surface and in the pores of the adsorbent without disassembling the adsorption device, and restore the adsorption activity, which is prior art and will not be described in detail here;

[0076] In response to the suspended matter removal rate being greater than or equal to the reference removal rate, the filtration precision of the pretreatment unit is increased (i.e., the metal membrane filtration device of the filter element is switched); it can be understood that when the suspended matter removal rate is less than the reference removal rate, the pretreatment unit is seriously failed, a large amount of impurities penetrate the filtration link, and the adsorbent pores may be blocked, at this time, the filtration precision of the pretreatment unit needs to be increased (such as replacing a high-precision metal membrane or increasing the filtration stages), more impurities are intercepted from the source, the adsorbent is prevented from being further polluted, and rapid failure after cleaning is prevented;

[0077] The reference removal rate is less than a preset removal rate.

[0078] It can be understood that the reference removal rate needs to be lower than the preset removal rate to distinguish between the two scenarios of slight failure and serious failure of the pretreatment unit and correspond to different intensity optimization measures; in implementation, 80% < reference removal rate < 90%, and the reference removal rate is preferably set to 85%; when the removal rate decreases to 85%, the impurities have started to penetrate, and the adsorbent needs to be cleaned in time to avoid the pollution from being aggravated.

[0079] Please refer to Figure 3 It is a workflow diagram of the dynamic execution module of the embodiment of the application. The dynamic execution module responds to the deterioration of the adsorption performance due to low adsorption kinetic efficiency, determines the optimization measure to be adjusting the real-time adsorption flow rate and the real-time adsorption temperature to the corresponding operating standard value in combination with the real-time adsorption flow rate and the real-time adsorption temperature, and in implementation, the operating standard value is the center value of the operating standard range.

[0080] It should be understood that when the adsorption performance deterioration reason is low adsorption kinetics efficiency, the main reason is that the adsorption rate of lithium ions on the surface of the adsorbent decreases, resulting in shortening of the adsorption breakthrough time; the adsorption flow rate directly determines the contact time of lithium ions with the adsorbent and the mass transfer efficiency, and too fast flow rate will make lithium ions flow out of the device without fully contacting the active sites of the adsorbent, and too slow flow rate will reduce the processing efficiency; adjusting the flow rate to the operating standard value can ensure that the contact time of lithium ions with the adsorbent is in the optimal interval, reduce the mass transfer resistance, and accelerate the adsorption reaction rate; temperature will affect the activation energy of the adsorption reaction and the ion diffusion rate, and too low temperature will reduce the ion diffusion speed and prolong the adsorption equilibrium time, and too high temperature may cause the activity of the adsorbent to decrease or the adsorption reaction to proceed in reverse; adjusting the temperature to the operating standard value can make the adsorption reaction in the best thermodynamic state and improve the adsorption kinetics efficiency.

[0081] Specifically, the dynamic execution module responds to the adsorption performance deterioration reason being low desorption kinetics efficiency, and determines the optimization measure according to the real-time desorption liquid concentration, and further comprises:

[0082] According to the real-time desorption liquid concentration being at or above the corresponding concentration operating range, it is determined that the optimization measure is to reduce the flow rate of the desorption liquid flowing through the adsorption device; it should be understood that when the desorption liquid concentration is in the concentration operating range, it means that the chemical driving force of the desorption liquid meets the basic requirements, that is, the concentration does not deviate from the reasonable interval, and the driving force of lithium ions desorbing from the active sites of the adsorbent is sufficient, and the root cause of low desorption kinetics efficiency is not insufficient driving force, but insufficient mass transfer contact, so reducing the flow rate can prolong the contact time, let the desorption liquid fully penetrate the adsorption bed, increase the opportunity of lithium ions desorbing and diffusing to the desorption liquid, and improve the desorption rate from the mass transfer level.

[0083] Wherein, the concentration operating range is greater than the corresponding concentration operating standard range; it can be understood that the concentration operating standard range is the ideal optimal interval of the desorption liquid concentration, and the concentration operating range is the acceptable buffer interval; the operation cost of adjusting the flow rate of the desorption liquid is much lower than that of adjusting the concentration, when the desorption liquid concentration is slightly higher or lower than the standard range but still within the operating range, the desorption process is optimized by adjusting the flow rate, a physical means, in priority, to avoid the increase of reagent consumption, process fluctuation and equipment start-stop loss caused by frequent adjustment of the concentration.

[0084] Specifically, the dynamic execution module responds to the adsorption performance deterioration reason being low desorption kinetics efficiency, and determines the optimization measure according to the real-time desorption liquid concentration, and further comprises:

[0085] According to the real-time analysis of the concentration of the eluent being lower than the corresponding concentration operation range, the optimization measure is determined to be adjusting the concentration of the eluent to be within the corresponding concentration operation standard range. It can be understood that if the concentration is too low, the concentration difference between the adsorbent and the eluent is insufficient, and even if the contact time is extended, the thermodynamic trend of lithium ion desorption is still weak, the elution peak concentration is difficult to improve, and the elution efficiency is still low, so the driving force must be supplemented by increasing the concentration.

[0086] It can be understood that when the adsorption performance degradation is caused by low elution kinetic efficiency, the main reason is that the rate of lithium ion desorption from the active sites of the adsorbent and diffusion to the eluent is reduced, resulting in a decrease in the elution peak concentration and an increase in the elution time. The concentration of the eluent is the chemical driving force for lithium ion desorption. When the concentration is too low, the concentration difference between the adsorbent and the eluent is reduced, and the desorption power is insufficient. When the concentration is too high, the reagent cost and subsequent wastewater treatment difficulty are increased. The flow rate of the eluent determines the contact time with the adsorbent. In the case of sufficient eluent concentration, reducing the flow rate can prolong the contact time between the eluent and the adsorbent, increase the opportunity for lithium ion desorption and diffusion to the eluent, and thus improve the elution rate and shorten the elution time.

[0087] So far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to related technical features without departing from the principles of the present application, and the technical solutions after such changes or replacements will fall within the protection scope of the present application.

[0088] The above description is only the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various changes and modifications to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A bauxite lithium extraction dynamic optimization system based on adsorption process feedback, applied to the following lithium extraction process: after pretreatment, the waste liquid is introduced into the adsorption device for selective adsorption of lithium, and after adsorption saturation, the desorption liquid is introduced for desorption to obtain a lithium-rich liquid, characterized in that, The dynamic optimization system comprises: a real-time monitoring module for continuously collecting relevant operating parameters of the adsorption process, the relevant operating parameters at least including adsorption breakthrough time and adsorption bed pressure drop in the adsorption stage, desorption peak concentration and desorption time in the desorption stage, and suspended solids removal rate in the pretreatment stage; a performance estimation module for determining a running standard range of the current adsorption operating parameters according to historical adsorption operating parameters, the adsorption operating parameters including adsorption temperature, feed pH value, and desorption liquid concentration; a hierarchical decision module for determining a performance characterization trend of the adsorption system according to the adsorption breakthrough time; and based on the determination result of overall performance degradation, a pressure drop change rate is calculated according to the adsorption bed pressure drop to determine the degradation cause of the adsorption performance in combination with the suspended solids removal rate, wherein: based on the determination result that the pressure drop change rate and the suspended solids removal rate satisfy a physical degradation condition, it is determined that the degradation cause of the adsorption performance is adsorption bed blockage caused by adsorption pollution; based on the determination result that the pressure drop change rate and the suspended solids removal rate do not satisfy the physical degradation condition, the desorption peak concentration and the desorption time are combined to determine the degradation cause of the adsorption performance; the hierarchical decision module calculates a concentration change rate and a time length change rate according to the desorption peak concentration and the desorption time respectively, and determines whether the degradation cause of the adsorption performance is low adsorption kinetics efficiency according to the concentration change rate, including: based on the determination result that the concentration change rate is greater than or equal to a concentration change rate threshold, it is determined that the degradation cause of the adsorption performance is low adsorption kinetics efficiency; otherwise, the time length change rate is combined to determine whether the degradation cause of the adsorption performance is low desorption kinetics efficiency; wherein the degradation causes include adsorption bed blockage caused by adsorption pollution, low adsorption kinetics efficiency, and low desorption kinetics efficiency; a dynamic execution module for determining optimization measures according to the degradation cause of the adsorption performance, including optimizing the waste liquid pretreatment process and adjusting the adsorption operating parameters of the adsorption device.

2. The adsorption process feedback-based dynamic optimization system for lithium extraction from bauxite according to claim 1, wherein, The hierarchical decision module calculates a shortening amplitude of the adsorption breakthrough time to determine the performance characterization trend of the adsorption device according to the adsorption breakthrough time, including: based on the determination result that the shortening amplitude is less than a preset amplitude, it is determined that the performance characterization trend of the adsorption device is normal overall performance and maintaining the current adsorption operating parameters; based on the determination result that the shortening amplitude is greater than or equal to the preset amplitude, it is determined that the performance characterization trend of the adsorption device is overall performance degradation and triggers the degradation cause diagnosis process.

3. The adsorption process feedback based bauxite to lithium dynamic optimization system of claim 1, wherein, The physical degradation condition is that the pressure drop change rate is greater than or equal to a preset change rate and the suspended solids removal rate is less than or equal to a preset removal rate.

4. The adsorption process feedback-based dynamic optimization system for lithium extraction from bauxite according to claim 1, wherein, The dynamic execution module, in response to the degradation cause of the adsorption performance being adsorption bed blockage caused by adsorption pollution, determines a method for optimizing the waste liquid pretreatment process according to the suspended solids removal rate, wherein: in response to the suspended solids removal rate being less than a benchmark removal rate, an adsorbent online cleaning program is started; in response to the suspended solids removal rate being greater than or equal to the benchmark removal rate, the filtration accuracy of the pretreatment unit is increased; wherein the benchmark removal rate is less than the preset removal rate.

5. The adsorption process feedback-based dynamic optimization system for lithium extraction from bauxite of claim 1, wherein, The dynamic execution module determines the optimization measure as adjusting the adsorption flow rate and the adsorption temperature to the corresponding operation standard values in response to the adsorption performance deterioration reason being low adsorption kinetic efficiency.

6. The adsorption process feedback-based dynamic optimization system for lithium extraction from bauxite of claim 1, wherein, The dynamic execution module determines the optimization measure according to the real-time elution liquid concentration in response to the adsorption performance deterioration reason being low elution kinetic efficiency, and further comprises: determining the optimization measure as reducing the flow rate of the elution liquid flowing through the adsorption device according to the real-time elution liquid concentration being at or above the corresponding concentration operation range; wherein the concentration operation range is greater than the corresponding concentration operation standard range.

7. The adsorption process feedback-based dynamic optimization system for lithium extraction from bauxite of claim 1, wherein, The dynamic execution module determines the optimization measure according to the real-time elution liquid concentration in response to the adsorption performance deterioration reason being low elution kinetic efficiency, and further comprises: determining the optimization measure as adjusting the elution liquid concentration to be within the corresponding concentration operation standard range according to the real-time elution liquid concentration being below the corresponding concentration operation range.

Images