Simulation method for countercurrent cascade extraction separation process of acidic extractant

Abstract

The invention discloses a simulation method for a countercurrent cascade extraction separation process of an acidic extraction agent, and belongs to the technical field of extraction separation. The invention provides a simulation method for a countercurrent cascade extraction separation process of an acid extractant based on system dynamics by comprehensively considering the comprehensive effect influence of extraction production input such as the content of a to-be-separated component of a feed liquid and the concentration of an organic phase extractant and extraction control factors such as a water phase flow rate and an organic phase flow rate on an extraction rate and a distribution ratio. Analog simulation of the countercurrent cascade extraction separation process of the acid extractant on the production site can be achieved, and the problems that in the prior art, a high-dimension differential equation set is difficult to solve, the deviation between a prediction result and the actual engineering situation is large, and use is difficult in enterprise production practice are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of extraction and separation, in particular to a simulation method for a countercurrent cascade extraction and separation process of an acidic extractant. Background Art

[0002] Cascade extraction is a separation technology based on the principle of multi-stage countercurrent extraction. It is mainly used for the efficient separation of metal elements with similar chemical properties. Its core lies in achieving component purification through continuous graded extraction and washing processes.

[0003] Rare earth extraction process simulation is the primary research platform for the reorganization of existing process flows and the re-optimization of process parameters. In the 1970s, Professor Xu Guangxian developed the theory of cascade extraction based on the theory of fractional distillation extraction. Subsequently, his team proposed static calculation and dynamic simulation methods for the rare earth cascade extraction process, providing a basis and guidance for the steady-state optimization and dynamic simulation of rare earth extraction. However, when dealing with multi-component rare earth extraction systems, the cascade extraction theory is prone to causing a large amount of root multiplication, which makes it difficult to calculate and judge the program. Since the actual production process of rare earth extraction will cause the composition of the feed liquid to vary due to different origins or batches of the incoming materials, to ensure the quality of the products at both ends, it is necessary to adjust and optimize the process parameters according to the different feed components. Currently, there is no intuitive and concrete rare earth extraction process simulation method that can meet the needs of current production sites.

[0004] Prior art generally simplifies the actual extraction and separation process in production, then solves it analytically by combining the material equilibrium state equations for the rare earth cascade extraction and separation process. The following are the main problems with prior art: First, solving high-dimensional differential equations is time-consuming and difficult due to the generation of root multiplication; second, the theoretical assumptions of the simplified model differ to a certain extent from the actual production situation, resulting in large deviations in the predicted results; third, the model in the form of a differential equation system is abstract and difficult to understand and adjust, making it inconvenient for front-line production employees to use in guiding production practices. The system dynamics modeling method is a simulation modeling method based on a differential equation system. It is concrete and easy to understand. Once the model is constructed, ordinary technicians can easily adjust the model control parameters to simulate and analyze the extraction and separation production process to explore the optimization of production process parameters. It is more suitable for application by enterprise technicians or production operators in production practices. Summary of the Invention

[0005] The purpose of the present invention is to provide a simulation method for the countercurrent cascade extraction separation process of an acidic extractant to solve the above-mentioned problems. It comprehensively considers the comprehensive effects of extraction production inputs such as the content of the components to be separated in the feed liquid, the concentration of the organic phase extractant, and the combined effects of extraction control factors such as the water phase flow rate and the organic phase flow rate on the extraction rate and the distribution ratio, so as to solve the problems in the prior art such as the difficulty in solving high-dimensional differential equations, the large deviation between the predicted results and the actual engineering conditions, and the difficulty in using the method in enterprise production practice.

[0006] To achieve the above object, the present invention discloses a simulation method for a countercurrent cascade extraction separation process of an acidic extractant, comprising the following steps:

[0007] S1. Establish an n-stage extraction tank model, where n is a positive integer greater than 3, the organic phase containing the extractant flows from the first-stage extraction tank to the n-stage extraction tank, and the aqueous phase containing the extracted component flows from the n-stage extraction tank to the first-stage extraction tank, and draw a cause-and-effect relationship diagram of the acidic extractant countercurrent cascade extraction system based on the influence relationship between the main variables in the acidic extractant countercurrent cascade extraction process in the n-stage extraction tank model;

[0008] S2. Based on the cause-effect relationship diagram of the acidic extractant countercurrent cascade extraction system, a flow rate diagram of the acidic extractant countercurrent cascade extraction system is drawn according to the change in the mass of the components to be separated in the organic phase and the aqueous phase in each extraction tank after the extraction reaction;

[0009] S3. Determine the flow rate equations for each flow rate in the flow rate diagram of the acidic extractant countercurrent cascade extraction system based on the equilibrium equation of the acidic extractant extraction reaction, and complete the construction of a simulation model for the acidic extractant countercurrent cascade extraction system;

[0010] S4, setting the simulation step of the simulation model, and assigning values ​​to control variables in the simulation model according to corresponding data of the simulated scene;

[0011] S5. Use the same data as the simulation to test the model at the production site or the experimental site. If the relative error between the model calculation result and the actual production or experimental data is less than 5%, it indicates that the constructed acidic extractant countercurrent cascade extraction simulation model is effective. Otherwise, the stage efficiency coefficient in the model is corrected according to the following formula:

[0012] I New =I Old ×[1-(V rn -V oan ) / V oan ]

[0013] Among them: I New is the corrected model-level efficiency coefficient, I Old is the model level efficiency coefficient before correction, V rnV is the actual value of the amount of the components to be separated in the organic phase flowing out of the last stage extraction tank, oan It is the simulated value of the amount of the components to be separated in the organic phase flowing out of the last stage extraction tank.

[0014] Preferably, in step S1, the main variables are the concentration of the component to be extracted in the aqueous phase, the concentration of the free extractant, and the concentration of the component to be extracted in the organic phase in each stage of extraction tanks;

[0015] In the cause-effect relationship diagram of the acidic extractant countercurrent cascade extraction system, the concentration of the component to be extracted in the organic phase in the same stage extraction tank affects the concentration of the component to be extracted in the aqueous phase and the concentration of the free extractant, and the concentration of the component to be extracted in the aqueous phase affects the concentration of the free extractant;

[0016] Between different stages of extraction tanks, the concentration of the component to be extracted in the organic phase of the i-th stage extraction tank is affected by the concentration of the component to be extracted in the organic phase of the i-1th stage extraction tank, the concentration of the free extractant, and the concentration of the component to be extracted in the aqueous phase of the i+1th stage extraction tank;

[0017] The concentration of the component to be extracted in the aqueous phase in the i-th stage extraction tank is affected by the concentration of the component to be extracted in the aqueous phase in the i+1-th stage extraction tank.

[0018] Preferably, the concentration of the component to be extracted in the organic phase is also affected by the acidity of the aqueous phase, the feed-liquid flow ratio and the extraction reaction constant.

[0019] Preferably, the flow rate diagram of the acidic extractant countercurrent cascade extraction system in step S2 is to establish the flow rate relationship of the components to be separated in the aqueous phase, the flow rate relationship of the components to be separated in the organic phase, and the flow rate relationship of the extractant in each stage of the extraction tank, wherein:

[0020] The flow rate relationship of the components to be separated in the aqueous phase is the flow rate of the components to be separated in the aqueous phase from the i-th extraction tank to the i-1-th extraction tank;

[0021] The flow rate relationship of the components to be separated in the organic phase is the flow rate of the components to be separated in the organic phase from the i-1 stage extraction tank to the i stage extraction tank;

[0022] The extractant flow rate relationship is the free extractant flow rate from the i-th stage extraction tank to the i-1-th stage extraction tank.

[0023] Preferably, the components to be separated are two components extracted by the extractant at the same time, and both components are any one of the rare earth elements.

[0024] Preferably, in the flow rate diagram of the acidic extractant countercurrent cascade extraction system in step S3, the two components are named A and B, respectively, and the flow rate relationship is the flow rate of the aqueous phase A, the flow rate of the aqueous phase B, the flow rate of the organic phase A, the flow rate of the organic phase B, and the flow rate of the free extractant, and the flow rate equations of each flow rate are:

[0025] (1)Roa i =[T / (Lo+Lw)]×γ a ×S×{Vwa i+1 -[(Ka×C i-1 3 ×Rwa i+1 ) / Pw 3 ]}×I;

[0026] (2)Rwa i =-Roa i ;

[0027] (3) Rob i =[T / (Lo+Lw)]×γ b ×S×{Vwb i+1 -[(Kb×C i-1 3 ×Rwb i+1 ) / Pw 3 ]}×I;

[0028] (4)Rwb i =-Rob i ;

[0029] (5)Roz i =-3×(Roa i +Rob i );

[0030] Where: i is one of the n-stage extraction tanks, 3≤i≤n-1; Roa i is the flow rate of organic phase A between the i-1th stage extraction tank and the i-th stage extraction tank, T is the effective volume of the extraction tank, Lo is the organic phase flow rate, Lw is the water phase flow rate, γ a is the mass transfer coefficient of A in the water phase, S is the contact area between the two phases, Vwa i+1 is the content of aqueous phase A in the i+1 stage extraction tank, Ka is the equilibrium constant of the extraction reaction of phase A, C i-1 Rwa is the free extractant dosage of the organic phase in the i-1 stage extraction tank, i+1 is the flow rate of aqueous phase A in the i+1 stage extraction tank, Pw is the acidity of the aqueous phase, and I is the stage efficiency coefficient; Rwa i is the flow rate of aqueous phase A between the i-th extraction tank and the i-1-th extraction tank; Rob i is the flow rate of organic phase B between the i-1th stage extraction tank and the i-th stage extraction tank, γ b is the mass transfer coefficient of B in water phase, Vwb i+1 is the content of B in the aqueous phase of the i+1 stage extraction tank, Kb is the equilibrium constant of the extraction reaction of B, C i-1 is the free extractant concentration of the organic phase in the i-1 stage extraction tank, Rwbi+1 Rwb is the flow rate of aqueous phase B in the i+1 stage extraction tank; i is the flow rate of water phase B from tank i to tank i-1; Roz i is the free extractant flow rate between the i-1th stage extraction tank and the i-th stage extraction tank.

[0031] Among them, the determination of the constant parameters in the flow rate equation (1) is:

[0032] The effective volume T of the extraction tank can be measured at the production site;

[0033] Mass transfer coefficient γ of component A in water phase a It can be determined by diffusion experiment of substance A;

[0034] The two-phase contact area S is related to the effective volume of the extraction tank mixing chamber, the two-phase flow rate and the stirring speed, and can be obtained by single tank experiment measurement;

[0035] The extraction reaction constant Ka of component A can be measured through the extraction experiment of substance A under this extraction system;

[0036] The stage efficiency coefficient I is generally taken as 0.9 according to experience, and can be adjusted according to the difference between the model simulation results and the actual production value.

[0037] Determination of constant parameters in flow rate equation (3):

[0038] The values ​​of the extraction tank effective volume T, two-phase contact area S, aqueous phase acidity P, and stage efficiency coefficient I are the same as those in the flow rate equation (1);

[0039] Mass transfer coefficient γ of component B in water phase b It can be determined by diffusion experiment of substance B under the same conditions;

[0040] The extraction reaction constant Kb of component B can be measured through the extraction experiment of substance B under this extraction system.

[0041] Preferably, the control variable value in the flow rate equation is determined in simulation:

[0042] According to the content of the components to be separated in the liquid determined by the simulation scenario, the flow variable content of the components A and B to be separated in the aqueous phase of the n-stage extraction tank is assigned initial values ​​Vwan and Vwbn;

[0043] According to the initial concentration of the organic phase extractant, the free extractant content in tank 1 is assigned an initial value Voz1;

[0044] The initial values ​​of the flow variables Voa1 and Vob1 of the organic phase components A and B to be separated are zero;

[0045] According to the simulation objectives, the control variable values ​​are set, including the extraction water phase flow rate, organic phase flow rate and water phase acidity, and the simulation model is run to simulate the extraction and separation process.

[0046] According to the simulation objectives, the control variable values ​​such as the extraction water phase flow rate, organic phase flow rate and water phase acidity are set, and the simulation model is run to simulate the extraction and separation process.

[0047] Preferably, in practical application, the extraction and separation production process parameters can be optimized based on the extraction and separation process simulation analysis:

[0048] The aqueous phase flow rate and the organic phase flow rate have a significant impact on the extraction and separation effect and are important control parameters for extraction and separation. In extraction and separation production, they are generally set based on the quality targets of the incoming materials and the extraction and separation output. In the simulation model, the aqueous phase flow rate and the organic phase flow rate are control variables. The simulation output results of different aqueous phase flow rate and organic phase flow rate values ​​can be used to optimize the values ​​of these two parameters.

[0049] The initial feed liquid acidity is also an important production process parameter set in advance for extraction and separation production. Because the acidic extractant extraction system generally uses the method of saponifying the organic phase to maintain the acidity of the aqueous phase, the acidity P of the aqueous phase in each tank during the extraction process is approximately equal to the initial feed liquid acidity. Similar to the aqueous phase flow rate and organic phase flow rate, the feed liquid acidity setting value can be optimized through simulation analysis of different values ​​of the aqueous phase acidity in the model.

[0050] The present invention proposes a simulation method for the acidic extractant countercurrent cascade extraction and separation process based on system dynamics. By comprehensively considering the comprehensive effects of extraction production inputs such as the content of the components to be separated in the feed liquid, the concentration of the organic phase extractant, and the extraction control factors such as the aqueous phase flow rate and the organic phase flow rate on the extraction rate and distribution ratio, the simulation method can be realized for the acidic extractant countercurrent cascade extraction and separation process at the production site.

[0051] Therefore, the present invention has the following beneficial effects:

[0052] (1) Solve the problem of difficulty in solving high-dimensional differential equations in the existing technology;

[0053] (2) Improve the accuracy of the model's simulation prediction of the actual extraction and separation production process;

[0054] (3) The simulation model of the present invention is intuitive and easy to understand by ordinary production staff of the enterprise, and is convenient for application in production practice;

[0055] (4) The simulation model of the present invention is used to perform simulation analysis of different production process conditions, thereby optimizing the production process parameters.

[0056] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is the cause and effect diagram of the acidic extractant countercurrent cascade extraction system;

[0058] Figure 2 This is the flow rate diagram of the acidic extractant countercurrent cascade extraction system;

[0059] Figure 3 Flow rate diagram for the implementation example. DETAILED DESCRIPTION

[0060] The technical solution of the present invention is further illustrated by the following examples.

[0061] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0062] Furthermore, it should be understood that although this specification describes the embodiments, not every embodiment includes only one independent technical solution. This description is for clarity only. Those skilled in the art should consider the specification as a whole. The technical solutions in the various embodiments may also be appropriately combined to form other embodiments that are understandable to those skilled in the art. These other embodiments are also encompassed within the scope of protection of the present invention.

[0063] The present invention discloses a simulation method for a countercurrent cascade extraction and separation process of an acidic extractant, comprising the following steps:

[0064] S1. Establish an n-stage extraction tank model, wherein n is a positive integer greater than 3, the aqueous phase flows from the n-stage extraction tank to the 1st-stage extraction tank, the acidic extractant is the organic phase, and the organic phase flows from the 1st-stage extraction tank to the n-stage extraction tank. Determine the main variables based on the key influencing factors in the countercurrent cascade extraction process of the acidic extractant in the n-stage extraction tank model, discuss the influence relationship between the main variables, and draw a cause-and-effect relationship diagram of the acidic extractant countercurrent cascade extraction system. The key influencing factors are the mass of the component to be separated in the feed liquid, the feed liquid flow rate, the mass of the extractant in the organic phase, the organic phase flow rate, the mass of the component to be separated in the aqueous phase of each stage of extraction tank, the mass of the component to be separated in the organic phase of each stage of extraction tank, the mass of the free extractant in the organic phase of each stage of extraction tank, the extraction reaction constant of the component to be separated, the acidity of the aqueous phase, the effective volume of the extraction tank, etc.; the main variables are the concentration of the component to be extracted in the aqueous phase of each stage of extraction tank, the concentration of the free extractant, and the concentration of the component to be extracted in the organic phase.

[0065] Cause and effect diagram of acidic extractant countercurrent cascade extraction system Figure 1As shown in the causal relationship diagram of the acidic extractant countercurrent cascade extraction system, the concentration of the component to be extracted in the organic phase in the same stage extraction tank affects the concentration of the component to be extracted in the aqueous phase and the concentration of the free extractant, and the concentration of the component to be extracted in the aqueous phase affects the concentration of the free extractant; between different stages of extraction tanks, the concentration of the component to be extracted in the organic phase of the i-th stage extraction tank is affected by the concentration of the component to be extracted in the organic phase and the concentration of the free extractant in the i-1-th stage extraction tank, and the concentration of the component to be extracted in the aqueous phase in the i+1-th stage extraction tank; the concentration of the component to be extracted in the aqueous phase in the i-th stage extraction tank is affected by the concentration of the component to be extracted in the aqueous phase in the i+1-th stage extraction tank.

[0066] S2. Based on the cause-effect relationship diagram of the acidic extractant countercurrent cascade extraction system, draw the flow rate diagram of the acidic extractant countercurrent cascade extraction system according to the change of the mass of the components to be separated in the organic phase and the aqueous phase in each extraction tank after the extraction reaction, such as Figure 2 As shown, the flow rate diagram of the acidic extractant countercurrent cascade extraction system is used to establish the flow rate relationship of the components to be separated in the aqueous phase, the flow rate relationship of the components to be separated in the organic phase, and the extractant flow rate relationship in each stage of extraction tank, wherein: the flow rate relationship of the components to be separated in the aqueous phase is the flow rate of the components to be separated in the aqueous phase from the i-th stage extraction tank to the i-1-th stage extraction tank; the flow rate relationship of the components to be separated in the organic phase is the flow rate of the components to be separated in the organic phase from the i-1-th stage extraction tank to the i-th stage extraction tank; the extractant flow rate relationship is the free extractant flow rate from the i-th stage extraction tank to the i-1-th stage extraction tank.

[0067] S3. According to the equilibrium equation of the extraction reaction of the acidic extractant, the flow rate equations of each flow rate in the flow rate diagram of the acidic extractant countercurrent cascade extraction system are determined to complete the construction of the simulation model of the acidic extractant countercurrent cascade extraction.

[0068] The concentration of the components to be extracted in the organic phase is also affected by the acidity of the aqueous phase, the feed-liquid flow ratio and the extraction reaction constant.

[0069] The components to be separated are two components extracted by the extractant at the same time, and the two components are any one of the metal elements.

[0070] In the flow rate diagram of the acidic extractant countercurrent cascade extraction system in step S3, the two components are named A and B, respectively. The flow rate relationship is the flow rate of aqueous phase A, the flow rate of aqueous phase B, the flow rate of organic phase A, the flow rate of organic phase B, and the flow rate of the extractant. The flow rate equations for each flow rate are derived as follows:

[0071] Acidic extractants extract metal ions (Me 3+ ) is a cation exchange reaction, and the equilibrium equation for the total acidic extractant extraction reaction is:

[0072] Me 3+ +3HX=MeX3+3H+

[0073] In the equation, Me 3+ is the metal ion to be extracted, HX is the extractant, H + For hydrogen ions.

[0074] The extraction equilibrium constant K is defined as:

[0075] K=[MeX3][H + ] 3 / {[Me 3+ ][HX] 3}

[0076] Wherein, [MeX3] is the concentration of the extracted metal ions bound by the organic phase extractant after extraction equilibrium, [H + ] is the hydrogen ion concentration in the organic phase, [Me 3+ ] is the concentration of extracted metal ions in the aqueous phase, and [HX] is the concentration of the extractant in the organic phase.

[0077] A simple transformation of the extraction equilibrium constant formula yields:

[0078] [MeX3]=K[Me 3+ ][HX] 3 / [H + ] 3

[0079] The extraction reaction occurs at the interface between the two phases. Due to the concentration difference, the diffusion mass transfer process of the extracted component A from the interface to the aqueous phase (organic phase) follows Fick's law:

[0080] J A =D A (dc A / dz)

[0081] Among them: J A is the diffusion flux of component A (the amount of substance passing through a unit area per unit time), D A is the diffusion coefficient of component A in medium B, dc A / dz is the concentration gradient along the diffusion direction z.

[0082] In the short time of one simulation step in the present invention, the above formula can be approximately simplified to:

[0083] J A =D A (C1-C2)

[0084] Wherein, C1 is the concentration of component A at the interface of aqueous phase (organic phase), and C2 is the concentration of component A in aqueous phase (organic phase).

[0085] According to the above derivation, the flow rate equation can be obtained:

[0086] Flow rate of aqueous phase A component from tank i to tank i-1

[0087] (1)Roa i =[T / (Lo+Lw)]×γ a ×S×{Vwa i+1 -[(Ka×C i-1 3 ×Rwa i+1 ) / Pw 3 ]}×I

[0088] Where: [(Ka × C i-1 3 ×Rwa i+1 ) / Pw 3 ] is the concentration of component A that is incorporated into the organic phase by the extractant due to the extraction reaction (derived from the extraction equilibrium equation).

[0089] (2)Rwa i =-Roa i ;

[0090] Flow rate of organic phase B component from tank i-1 to tank i

[0091] (3) Rob i =[T / (Lo+Lw)]×γ b ×S×{Vwb i+1 -[(Kb×C i-1 3 ×Rwb i+1 ) / Pw 3 ]}×I

[0092] Where: [(Kb×C i-1 3 ×Rwb i+1 ) / Pw 3 ] is the concentration of component B incorporated into the organic phase by the extractant due to the extraction reaction.

[0093] (4)Rwb i =-Rob i ;

[0094] (5)Roz i =-3×(Roa i +Rob i );

[0095] Where: i is one of the n-stage extraction tanks, 3≤i≤n-1; Roa i is the flow rate of organic phase A between the i-1th stage extraction tank and the i-th stage extraction tank, T is the effective volume of the extraction tank, Lo is the organic phase flow rate, Lw is the water phase flow rate, γa is the mass transfer coefficient of A in the water phase, S is the contact area between the two phases, Vwa i+1 is the content of aqueous phase A in the i+1 stage extraction tank, Ka is the equilibrium constant of the extraction reaction of phase A, C i-1 Rwa is the free extractant dosage of the organic phase in the i-1 stage extraction tank, i+1 is the flow rate of aqueous phase A in the i+1 stage extraction tank, Pw is the acidity of the aqueous phase, and I is the stage efficiency coefficient; Rwa i is the flow rate of aqueous phase A between the i-th extraction tank and the i-1-th extraction tank; Rob i is the flow rate of organic phase B between the i-1th stage extraction tank and the i-th stage extraction tank, γ b is the mass transfer coefficient of B in water phase, Vwb i+1 is the content of B in the aqueous phase of the i+1 stage extraction tank, Kb is the equilibrium constant of the extraction reaction of B, C i-1 is the free extractant concentration of the organic phase in the i-1 stage extraction tank, Rwb i+1 Rwb is the flow rate of aqueous phase B in the i+1 stage extraction tank; i is the flow rate of water phase B from tank i to tank i-1; Roz i is the free extractant flow rate between the i-1th stage extraction tank and the i-th stage extraction tank.

[0096] Among them, the determination of constant parameters in the flow rate equation: the effective volume T of the extraction tank can be measured at the production site; the mass transfer coefficient γ of component A in the aqueous phase a It can be determined through the diffusion experiment of substance A; the two-phase contact area S is related to the effective volume of the mixing chamber of the extraction tank, the two-phase flow rate and the stirring speed, and can be obtained by single-tank experiment measurement; the extraction reaction constant Ka of component A can be measured through the extraction experiment of substance A under this extraction system; the stage efficiency coefficient I is generally taken as 0.9 according to experience, and can be adjusted according to the difference between the model simulation results and the actual production value.

[0097] Determination of constant parameters in flow rate equation (3): effective volume of extraction tank T, contact area of ​​two phases S, acidity of aqueous phase P, stage efficiency coefficient I are the same as those in flow rate equation (1); mass transfer coefficient of component B in aqueous phase γ b It can be determined through a diffusion experiment of substance B under the same conditions; the extraction reaction constant Kb of component B can be determined through an extraction experiment of substance B under this extraction system.

[0098] Determination of the control variable value in the flow rate equation in simulation:

[0099] According to the content of the components to be separated in the slurry determined by the simulation scenario, the flow variables Vwan and Vwbn of the components A and B to be separated in the aqueous phase of the n-stage extraction tank are assigned initial values; according to the initial concentration of the organic phase extractant, the free extractant content in the first tank is assigned an initial value Voz1; the flow variables Voa1 and Vob1 of the organic phase components A and B to be separated are initially zero; according to the simulation objectives, the control variable values ​​are set, including the extraction aqueous phase flow rate, the organic phase flow rate and the aqueous phase acidity, and the simulation model is run to simulate the extraction and separation process.

[0100] According to the simulation objectives, the control variable values ​​such as the extraction water phase flow rate, organic phase flow rate and water phase acidity are set, and the simulation model is run to simulate the extraction and separation process.

[0101] In practical applications, the extraction and separation production process parameters can be optimized based on the extraction and separation process simulation analysis:

[0102] The aqueous phase flow rate and the organic phase flow rate have a significant impact on the extraction and separation effect and are important control parameters for extraction and separation. In extraction and separation production, they are generally set based on the quality targets of the incoming materials and the extraction and separation output. In the simulation model, the aqueous phase flow rate and the organic phase flow rate are control variables. The simulation output results of different aqueous phase flow rate and organic phase flow rate values ​​can be used to optimize the values ​​of these two parameters.

[0103] The initial feed liquid acidity is also an important production process parameter set in advance for extraction and separation production. Because the acidic extractant extraction system generally uses the method of saponifying the organic phase to maintain the acidity of the aqueous phase, the acidity P of the aqueous phase in each tank during the extraction process is approximately equal to the initial feed liquid acidity. Similar to the aqueous phase flow rate and organic phase flow rate, the feed liquid acidity setting value can be optimized through simulation analysis of different values ​​of the aqueous phase acidity in the model.

[0104] S4. Set the simulation step of the simulation model and assign values ​​to the control variables in the simulation model according to the corresponding data of the simulated scene.

[0105] S5. Use the same data as the simulation to test the model at the production site or the experimental site. If the relative error between the model calculation result and the actual production or experimental data is less than 5%, it indicates that the constructed acidic extractant countercurrent cascade extraction simulation model is effective. Otherwise, the stage efficiency coefficient in the model is corrected according to the following formula:

[0106] I New =I Old ×[1-(V rn -V oan ) / V oan ]

[0107] Among them: I New is the corrected model-level efficiency coefficient, I Old is the model level efficiency coefficient before correction, Vrn V is the actual value of the amount of the components to be separated in the organic phase flowing out of the last stage extraction tank, oan It is the simulated value of the amount of the components to be separated in the organic phase flowing out of the last stage extraction tank.

[0108] Example 1

[0109] The method of the present invention is used to simulate the process of countercurrent extraction and separation of gadolinium and samarium in a 4-stage P507 system, including the following steps:

[0110] Step 1: The key influencing factors of the countercurrent extraction separation of gadolinium and samarium in the four-stage P507 system are determined to be the amount of A in the treated feed liquid, the amount of B in the treated feed liquid, the flow rate of the extraction aqueous phase, the P507 content in the organic phase, the flow rate of the extraction organic phase, the A content of the aqueous phase in the 1-4 stage extraction tanks, the B content of the aqueous phase in the 1-4 stage extraction tanks, the A content of the organic phase in the 1-4 stage extraction tanks, the B content of the organic phase in the 1-4 stage extraction tanks, the free extractant content of the organic phase in the 1-4 stage extraction tanks, the equilibrium constant of the extraction reaction A, the equilibrium constant of the extraction reaction B, the acidity of the aqueous phase, the effective volume of the extraction tank, the mass transfer coefficient of A in the aqueous phase, the mass transfer coefficient of B in the aqueous phase, and the contact area between the two phases.

[0111] Step 2: The flow rate diagram of the 4-stage P507 countercurrent extraction process for gadolinium and samarium is as follows: Figure 3 shown.

[0112] Step 3: The flow rate equations in the flow rate diagram of the 4-stage P507 countercurrent extraction process for gadolinium and samarium are determined as follows:

[0113] (1) The effective volume T of the extraction tank was measured to be 0.6, the contact area S of the two phases was 0.2, and the mass transfer coefficient γ of Gd in the aqueous phase was measured by experiments. a = 0.15, the gadolinium Gd extraction reaction constant Ka is 0.05, and the stage efficiency coefficient I is 0.9, then the organic phase Gd flow rate equation of each tank can be obtained:

[0114] Roa1=[0.6 / (Lo+Lw)]×0.03×{Vwa2-[(0.05×C1 3 ×Rwa2) / Pw 3 ]}×0.9; Roa2=[0.6 / (Lo+Lw)]×0.03×{Vwa3-[(0.05×C2 3 ×Rwa3) / Pw 3 ]}×0.9; Roa3=[0.6 / (Lo+Lw)]×0.03×{Vwa4-[(0.05×C3 3 ×Rwa4) / Pw 3 ]}×0.9;

[0115] (2) Gd flow rate equation of each tank water phase:

[0116] Rwa1=-Roa1;

[0117] Rwa2=-Roa2;

[0118] Rwa3=-Roa3;

[0119] (3) The mass transfer coefficient γ of Sm in the water phase was measured experimentally. a = 0.13, the samarium Sm extraction reaction constant Ka is equal to 0.01, and the stage efficiency coefficient I is 0.9, then the flow rate equation of the organic phase Sm in each tank can be obtained:

[0120] Rob1=[0.6 / (Lo+Lw)]×0.026×{Vwb2-[(0.01×C1 3 ×Rwb2) / Pw 3 ]}×0.9;

[0121] Rob2=[0.6 / (Lo+Lw)]×0.026×{Vwb3-[(0.01×C2 3 ×Rwb3) / Pw 3 ]}×0.9;

[0122] Rob3=[0.6 / (Lo+Lw)]×0.026×{Vwb4-[(0.01×C3 3 ×Rwb4) / Pw 3 ]}×0.9;

[0123] (4) Gd flow rate equation of each tank water phase:

[0124] Rwb1=-Rob1;

[0125] Rwb2=-Rob2;

[0126] Rwb3=-Rob3;

[0127] (5) Free extractant flow rate equation:

[0128] Roz1=-3×(Roa1+Rob1);

[0129] Roz2 = -3 × (Roa2 + Rob2);

[0130] Roz3=-3×(Roa3+Rob3);

[0131] Step 4: The model was tested using experimental data from the countercurrent extraction separation of gadolinium and samarium using a four-stage P507 system. The relative error between the model simulation results and the experimental data was 2.6%<5%, indicating that the constructed simulation model for the countercurrent extraction separation of gadolinium and samarium using a four-stage P507 system was effective.

[0132] Example 2

[0133] The method of the present invention was used to simulate the countercurrent extraction and separation of gadolinium and samarium in a 4-stage P507 system by selecting different flow ratios (organic phase flow rate / aqueous phase flow rate). The simulation results are shown in the following table:

[0134]

[0135] The above simulation results show that in the four-stage P507 system countercurrent extraction separation process for gadolinium and samarium, the separation coefficient (gadolinium distribution ratio / samarium distribution ratio) is minimized when the control parameter flow ratio is selected as 12. That is, when other extraction reaction conditions are determined, the optimal value of the control parameter flow ratio is 12.

[0136] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A simulation method for a countercurrent cascade extraction separation process using an acidic extractant, characterized in that: The following steps are involved: S1. Establish an n-stage extraction tank model, where n is a positive integer greater than 3, the organic phase containing the extractant flows from the first-stage extraction tank to the n-stage extraction tank, and the aqueous phase containing the extracted component flows from the n-stage extraction tank to the first-stage extraction tank, and draw a cause-and-effect relationship diagram of the acidic extractant countercurrent cascade extraction system based on the influence relationship between the main variables in the acidic extractant countercurrent cascade extraction process in the n-stage extraction tank model; S2. Based on the cause-effect relationship diagram of the acidic extractant countercurrent cascade extraction system, a flow rate diagram of the acidic extractant countercurrent cascade extraction system is drawn according to the change in the mass of the components to be separated in the organic phase and the aqueous phase in each extraction tank after the extraction reaction; S3. Determine the flow rate equations for each flow rate in the flow rate diagram of the acidic extractant countercurrent cascade extraction system based on the equilibrium equation of the acidic extractant extraction reaction, and complete the construction of a simulation model for the acidic extractant countercurrent cascade extraction system; S4, setting the simulation step of the simulation model, and assigning values ​​to control variables in the simulation model according to corresponding data of the simulated scene; S5. Use the same data as the simulation to test the model at the production site or the experimental site. If the relative error between the model calculation result and the actual production or experimental data is less than 5%, it indicates that the constructed acidic extractant countercurrent cascade extraction simulation model is effective. Otherwise, the stage efficiency coefficient in the model is corrected according to the following formula: I New =I Old ×[1-(V rn -V oan ) / V oan ] Among them: I New is the corrected model-level efficiency coefficient, I Old is the model level efficiency coefficient before correction, V rn V is the actual value of the amount of the components to be separated in the organic phase flowing out of the last stage extraction tank, oan It is the simulated value of the amount of the components to be separated in the organic phase flowing out of the last stage extraction tank.

2. The method for simulating a countercurrent cascade extraction separation process using an acidic extractant according to claim 1, wherein: In step S1, the main variables are the concentration of the component to be extracted in the aqueous phase, the concentration of the free extractant, and the concentration of the component to be extracted in the organic phase in each extraction tank; In the cause-effect relationship diagram of the acidic extractant countercurrent cascade extraction system, the concentration of the component to be extracted in the organic phase in the same stage extraction tank affects the concentration of the component to be extracted in the aqueous phase and the concentration of the free extractant, and the concentration of the component to be extracted in the aqueous phase affects the concentration of the free extractant; Between different stages of extraction tanks, the concentration of the component to be extracted in the organic phase of the i-th stage extraction tank is affected by the concentration of the component to be extracted in the organic phase of the i-1th stage extraction tank, the concentration of the free extractant, and the concentration of the component to be extracted in the aqueous phase of the i+1th stage extraction tank; The concentration of the component to be extracted in the aqueous phase in the i-th stage extraction tank is affected by the concentration of the component to be extracted in the aqueous phase in the i+1-th stage extraction tank.

3. The method for simulating a countercurrent cascade extraction separation process using an acidic extractant according to claim 2, wherein: The concentration of the components to be extracted in the organic phase is also affected by the acidity of the aqueous phase, the feed-liquid flow ratio and the extraction reaction constant.

4. The method for simulating a countercurrent cascade extraction separation process using an acidic extractant according to claim 1, wherein: The flow rate diagram of the acidic extractant countercurrent cascade extraction system in step S2 is used to establish the relationship between the flow rates of the components to be separated in the aqueous phase, the flow rates of the components to be separated in the organic phase, and the flow rate of the extractant in each stage of the extraction tank, wherein: The flow rate relationship of the components to be separated in the aqueous phase is the flow rate of the components to be separated in the aqueous phase from the i-th extraction tank to the i-1-th extraction tank; The flow rate relationship of the components to be separated in the organic phase is the flow rate of the components to be separated in the organic phase from the i-1 stage extraction tank to the i stage extraction tank; The extractant flow rate relationship is the free extractant flow rate from the i-th stage extraction tank to the i-1-th stage extraction tank.

5. The method for simulating a countercurrent cascade extraction separation process using an acidic extractant according to claim 4, wherein: The components to be separated are two components extracted by the extractant at the same time, and both components are any one of the metal elements.

6. The method for simulating a countercurrent cascade extraction separation process using an acidic extractant according to claim 1, wherein: In the flow rate diagram of the acidic extractant countercurrent cascade extraction system in step S3, the two components are named A and B, respectively. The flow rate relationship is the flow rate of aqueous phase A, the flow rate of aqueous phase B, the flow rate of organic phase A, the flow rate of organic phase B, and the flow rate of the extractant. The flow rate equations for each flow rate are: Roa i =[T / (Lo+Lw)]×γ a ×S×{Voice i+1 -[(Ka×C i-1 3 ×King i+1 ) / Pw 3 ]}×I; Red i =-Long i ; Rob i =[T / (Lo+Lw)]×γ b ×S×{Vwb i+1 -[(Kb×C i-1 3 ×Rwb i+1 ) / Pw 3 ]}×I; Rubbish i =-Rob i ; Pink i =-3×(Roa i +Rob i ); Where: i is one of the n-stage extraction tanks, 3≤i≤n-1; Roa i is the flow rate of organic phase A between the i-1th stage extraction tank and the i-th stage extraction tank, T is the effective volume of the extraction tank, Lo is the organic phase flow rate, Lw is the water phase flow rate, γ a is the mass transfer coefficient of A in the water phase, S is the contact area between the two phases, Vwa i+1 is the content of aqueous phase A in the i+1 stage extraction tank, Ka is the equilibrium constant of the extraction reaction of phase A, C i-1 Rwa is the free extractant dosage of the organic phase in the i-1 stage extraction tank, i+1 is the flow rate of aqueous phase A in the i+1 stage extraction tank, Pw is the acidity of the aqueous phase, and I is the stage efficiency coefficient; Rwa i is the flow rate of aqueous phase A between the i-th extraction tank and the i-1-th extraction tank; Rob i is the flow rate of organic phase B between the i-1th stage extraction tank and the i-th stage extraction tank, γ b is the mass transfer coefficient of B in water phase, Vwb i+1 is the content of B in the aqueous phase of the i+1 stage extraction tank, Kb is the equilibrium constant of the extraction reaction of B, C i-1 is the free extractant concentration of the organic phase in the i-1 stage extraction tank, Rwb i+1 Rwb is the flow rate of aqueous phase B in the i+1 stage extraction tank; i is the flow rate of water phase B from tank i to tank i-1; Roz i is the free extractant flow rate between the i-1th stage extraction tank and the i-th stage extraction tank.

7. The method for simulating a countercurrent cascade extraction separation process using an acidic extractant according to claim 6, wherein: Determination of the control variable value in the flow rate equation in simulation: According to the content of the components to be separated in the liquid determined by the simulation scenario, the initial values ​​of the flow variable content of the components A and B to be separated in the aqueous phase of the n-stage extraction tank are assigned as Vwan and Vwbn respectively; According to the initial concentration of the organic phase extractant, the free extractant content in tank 1 is assigned an initial value Voz1; The initial values ​​of the flow variables Voa1 and Vob1 of the organic phase components A and B to be separated are 0; According to the simulation objectives, the control variable values ​​are set, including the extraction water phase flow rate, organic phase flow rate and water phase acidity, and the simulation model is run to simulate the extraction and separation process.

8. The method for simulating a countercurrent cascade extraction separation process using an acidic extractant according to claim 1, wherein: The optimization of the two parameters is carried out through the simulation output results of different water phase flow rate and organic phase flow rate values; During the extraction process, the acidity P of the aqueous phase in each tank is equal to the initial feed acidity. The aqueous phase flow rate and the organic phase flow rate are optimized by simulation analysis of different values ​​of aqueous phase acidity in the model to find the optimal feed acidity setting value.

Images