A Simulation Method for Countercurrent Cascade Extraction Separation Process with Acidic Extractant

Abstract

This invention discloses a simulation method for a countercurrent cascade extraction separation process using acidic extractants, belonging to the field of extraction separation technology. Considering the combined effects of extraction production inputs such as the content of the components to be separated in the feed solution, the concentration of the organic phase extractant, and extraction control factors such as the flow rates of the aqueous and organic phases on the extraction rate and distribution ratio, a simulation method for a countercurrent cascade extraction separation process using acidic extractants based on system dynamics is proposed. This method can simulate the countercurrent cascade extraction separation process of acidic extractants in production settings, solving problems such as the difficulty in solving high-dimensional differential equations, large deviations between predicted results and actual engineering conditions, and difficulty in practical application in enterprise production in existing technologies.

Description

Technical Field

[0001] This invention relates to the field of extraction and separation technology, and in particular to a simulation method for a countercurrent cascade extraction and separation process using an acidic extractant. Background Technology

[0002] Cascade extraction is a separation technique 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 the purification of components through continuous fractional extraction and washing processes.

[0003] Rare earth extraction process simulation is a major research platform for the restructuring of existing processes and the re-optimization of process parameters. In the 1970s, Professor Xu Guangxian created the cascade extraction theory based on fractional extraction theory. Subsequently, his team proposed static and dynamic simulation methods for rare earth cascade extraction processes, providing a basis and guidance for steady-state optimization and dynamic simulation of rare earth extraction. However, cascade extraction theory is prone to causing a large number of root-like structures when dealing with multi-component rare earth extraction systems, making program calculations and judgments difficult. Because the composition of the feed liquid varies due to different origins or batches of raw materials in actual rare earth extraction production, it is necessary to adjust and optimize process parameters according to different feed components to ensure product quality at both ends. Currently, there is no intuitive and concrete rare earth extraction process simulation method that can meet the needs of current production sites.

[0004] Current technologies typically involve simplifying the extraction and separation process in actual production, then solving the system of material equilibrium equations for the rare earth cascade extraction and separation process analytically. However, these existing technologies suffer from several problems: First, solving high-dimensional differential equations is time-consuming, and the presence of extraneous roots can lead to difficulties. Second, the theoretical assumptions of the simplified model differ from actual production conditions, resulting in significant deviations in predictions. Third, the abstract nature of differential equation models makes them difficult to understand and adjust, hindering their application to frontline production staff. System dynamics modeling, based on difference equations, is a simulation modeling method that is visual and easy to understand. Once the model is built, ordinary technicians can easily adjust the model's control parameters to simulate and analyze the extraction and separation process, exploring ways to optimize process parameters. This approach is well-suited for application by enterprise technicians and production operators in practical production. Summary of the Invention

[0005] The purpose of this invention is to provide a simulation method for the countercurrent cascade extraction separation process of acidic extractant, which solves the above-mentioned problems. It comprehensively considers the combined 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 extraction control factors such as the flow rate of the aqueous phase and the flow rate of the organic phase on the extraction rate and distribution ratio. This solves the problems of difficulty in solving high-dimensional differential equations, large deviation between prediction results and actual engineering conditions, and difficulty in use in enterprise production practice in the prior art.

[0006] To achieve the above objectives, this invention discloses a simulation method for a countercurrent cascade extraction separation process using 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. Based on the influence relationship between the main variables in the acidic extractant countercurrent cascade extraction process in the n-stage extraction tank model, draw a causal relationship diagram of the acidic extractant countercurrent cascade extraction system.

[0008] S2. Based on the cause-and-effect diagram of the acidic extractant countercurrent cascade extraction system, and according to the changes in the mass of the components to be separated after the extraction reaction in the organic and aqueous phases of each extraction tank, draw the flow level and flow rate diagram of the acidic extractant countercurrent cascade extraction system.

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

[0010] S4. Set the simulation step size of the simulation model, and assign values ​​to the control variables in the simulation model according to the corresponding data of the simulated scenario;

[0011] S5. Use the same data as the simulation to verify the model at the production or experimental site. If the relative error between the model calculation results 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 should be corrected according to the following formula:

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

[0013] Among them: I New For the corrected model-level efficiency coefficient, I Old To correct the efficiency coefficients of the previous model, V rnV represents the actual amount of the component to be separated in the organic phase effluent from the last stage extraction tank. oan This represents the simulated amount of the component 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 extraction tank.

[0015] In the cause-and-effect diagram of the acidic extractant countercurrent cascade extraction system, the concentration of the extractable component in the organic phase within the same extraction tank affects the concentration of the extractable component in the aqueous phase and the concentration of the free extractant, and the concentration of the extractable component 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-1-th 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+1-th stage extraction tank.

[0017] The concentration of the component to be extracted in the aqueous phase of the i-th stage extraction tank is affected by the concentration of the component to be extracted in the aqueous phase of 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, in step S2, the flow rate diagram of the acidic extractant countercurrent cascade extraction system establishes the flow rate relationships of the components to be separated in the aqueous phase, the components to be separated in the organic phase, and the extractant flow rate in each 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 stage extraction tank to the (i-1)-th stage 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)th stage extraction tank to the ith 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 that are simultaneously extracted by the extractant, 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 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 free extractant. The flow rate equations for each flow rate are as follows:

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

[0031] The determination of constant parameters in the flow rate equation (1) is as follows:

[0032] The effective volume T of the extraction tank can be measured on-site during production.

[0033] The mass transfer coefficient γ of component A in the aqueous phase a It can be determined by diffusion experiments of substance A;

[0034] The contact area S between the two phases is related to the effective volume of the mixing chamber of the extraction tank, the flow rate of the two phases, and the stirring speed, and can be obtained by single-tank experimental calculation.

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

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

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

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

[0039] The mass transfer coefficient γ of component B in the aqueous phase b It can be determined by diffusion experiments of substance B under the same conditions;

[0040] The extraction reaction constant Kb of component B can be determined through extraction experiments of substance B in this extraction system.

[0041] Preferably, the values ​​of the control variables in the flow rate equation are determined in the simulation:

[0042] Based on the content of the components to be separated in the feed liquid determined by the simulation scenario, the initial values ​​Vwan and Vwbn are assigned to the content of the flow potential variables of components A and B to be separated in the aqueous phase of the nth stage extraction tank.

[0043] The initial value Voz1 is assigned to the content of the free extractant in the first tank based on the initial concentration of the organic phase extractant.

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

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

[0046] Based on the simulation objectives, control variables such as the extraction aqueous phase flow rate, organic phase flow rate, and aqueous phase acidity are set, and the simulation model is run to simulate the extraction and separation process.

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

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

[0049] The initial acidity of the feed solution is also an important process parameter that is set in advance in the 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 acidity of the feed solution, similar to the aqueous phase flow rate and the organic phase flow rate. The set value of the feed solution acidity can be optimized through simulation analysis of different values ​​of aqueous phase acidity in the model.

[0050] This invention proposes a simulation method for the countercurrent cascade extraction and separation process of acidic extractants based on system dynamics. It comprehensively considers the combined effects of extraction production inputs such as the content of components to be separated in the feed liquid and the concentration of organic phase extractant, as well as extraction control factors such as the flow rate of the aqueous phase and the flow rate of the organic phase on the extraction rate and distribution ratio. This method can simulate the countercurrent cascade extraction and separation process of acidic extractants in 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 equation systems in existing technologies;

[0053] (2) Improve the accuracy of the model in simulating and predicting 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 workers in enterprises, and is easy to apply in production practice;

[0055] (4) By using the simulation model of the present invention to perform simulation analysis under different production process conditions, the optimization of production process parameters can be achieved.

[0056] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0057] Figure 1 A cause-and-effect diagram for an acidic extractant countercurrent cascade extraction system;

[0058] Figure 2 Flow level and flow rate diagram for an acidic extractant countercurrent cascade extraction system;

[0059] Figure 3 To implement an example flow rate graph. Detailed Implementation

[0060] The technical solution of the present invention will be further described below through examples and embodiments.

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

[0062] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. These other embodiments are also covered within the scope of protection of this invention.

[0063] This invention discloses a simulation method for a countercurrent cascade extraction separation process using an acidic extractant, comprising the following steps:

[0064] S1. Establish an n-stage extraction tank model, where n is a positive integer greater than 3. The aqueous phase flows from the nth stage extraction tank to the first stage extraction tank, and the acidic extractant is the organic phase, which flows from the first stage extraction tank to the nth stage extraction tank. Based on the key influencing factors in the countercurrent cascade extraction process of the acidic extractant in the n-stage extraction tank model, determine the main variables, discuss the influence relationship between the main variables, and draw a causal 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 in each extraction tank, the mass of the component to be separated in the organic phase in each extraction tank, the mass of the free extractant in the organic phase in each extraction tank, the extraction reaction constant of the component to be separated, the acidity of the aqueous phase, and the effective volume of the extraction tank. 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.

[0065] The cause-and-effect diagram of the acidic extractant countercurrent cascade extraction system is as follows: Figure 1As shown in the causal relationship diagram of the acidic extractant countercurrent cascade extraction system, the concentration of the extractable component in the organic phase within the same extraction tank affects the concentration of the extractable component in the aqueous phase and the concentration of the free extractant, while the concentration of the extractable component in the aqueous phase affects the concentration of the free extractant. Between different extraction tanks, the concentration of the extractable component in the organic phase of the i-th extraction tank is affected by the concentration of the extractable component in the organic phase and the concentration of the free extractant in the i-1-th extraction tank, and the concentration of the extractable component in the aqueous phase of the i+1-th extraction tank; the concentration of the extractable component in the aqueous phase of the i-th extraction tank is affected by the concentration of the extractable component in the aqueous phase of the i+1-th extraction tank.

[0066] S2. Based on the cause-and-effect diagram of the acidic extractant countercurrent cascade extraction system, and according to the changes in the mass of the components to be separated after the extraction reaction in the organic and aqueous phases of each extraction tank, draw a flow level and flow rate diagram of the acidic extractant countercurrent cascade extraction system, such as... Figure 2 As shown, the flow rate diagram of the acidic extractant countercurrent cascade extraction system establishes the flow rate relationships of the components to be separated in the aqueous phase, the components to be separated in the organic phase, and the extractant flow rate in each extraction tank. Specifically: the flow rate relationship of the components to be separated in the aqueous phase refers to 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 refers to the flow rate of the components to be separated in the organic phase from the (i-1)-th extraction tank to the i-th extraction tank; and the flow rate relationship of the extractant refers to the free extractant flow rate from the i-th extraction tank to the (i-1)-th extraction tank.

[0067] S3. Based on the equilibrium equation of the extraction reaction of the acidic extractant, determine the flow rate equations for each flow rate in the flow rate diagram of the acidic extractant countercurrent cascade extraction system, and complete the construction of a simulation model for the acidic extractant countercurrent cascade extraction.

[0068] 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.

[0069] The components to be separated are two components that are simultaneously extracted by the extractant, and both 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 relationships are: aqueous phase A flow rate, aqueous phase B flow rate, organic phase A flow rate, organic phase B flow rate, and extractant flow rate. The flow rate equations for each flow rate are derived as follows:

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

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

[0073] In the equation, Me 3+ The metal ions to be extracted are HX, which is the extractant. + It is a hydrogen ion.

[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 extracted metal ions bound to the organic phase extractant after extraction equilibrium, [H + [Me] represents the hydrogen ion concentration in the organic phase. 3+ [HX] represents the concentration of the extracted metal ions in the aqueous phase, and [HX] represents 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. The diffusion mass transfer process of the extracted component A from the interface to the interior of the aqueous phase (organic phase) due to the concentration difference follows Fick's law:

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

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

[0082] Within a short simulation step time in this invention, the above equation can be approximately simplified to:

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

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

[0085] The flow rate equation can be obtained based on the above derivation:

[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 [ ] represents the concentration of component A that is bound to the extractant and enters the organic phase 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 [This represents the concentration of component B that is bound to the extractant and enters the organic phase due to the extraction reaction.]

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

[0094] (5) Roz i = -3×(Roa) i +Rob i );

[0095] Where: i is the first stage in the n-stage extraction tank, 3≤i≤n-1; Roa i Let γ be the flow rate of organic phase A between the (i-1)th stage extraction tank and the ith stage extraction tank, T be the effective volume of the extraction tank, Lo be the organic phase flow rate, Lw be the aqueous phase flow rate, and γ be the organic phase flow rate.a Let Vwa be the mass transfer coefficient of A in the aqueous phase, S be the contact area between the two phases, and Vwa be the mass transfer coefficient of A in the aqueous phase. i+1 Let C be the content of aqueous phase A in the (i+1)th stage extraction tank, Ka be the equilibrium constant of the extraction reaction of phase A, and C be the concentration of aqueous phase A. i-1 Rwa is the free extraction dose of the organic phase in the (i-1)th stage extraction tank. i+1 Rwa represents the flow rate of aqueous phase A in the (i+1)th stage extraction tank, Pw represents the acidity of the aqueous phase, and I represents the stage efficiency coefficient. i Rob represents the aqueous phase flow rate A between the i-th stage extraction tank and the (i-1)-th stage extraction tank; i γ is the flow rate of organic phase B between the (i-1)th stage extraction tank and the ith stage extraction tank. b Let Vwb be the mass transfer coefficient of B in the aqueous phase. i+1 Let C be the content of B in the aqueous phase of the (i+1)th stage extraction tank, Kb be the equilibrium constant of the extraction reaction of B, and C be the content of B in the aqueous phase of the (i+1)th stage extraction tank. i-1 Rwb represents the concentration of the free extractant in the organic phase of the (i-1)th stage extraction tank. i+1 Rwb represents the flow rate of aqueous phase B in the (i+1)th stage extraction tank. i Roz represents the flow rate of water phase B from tank i to tank i-1; i The free extractant flow rate is between the (i-1)th 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 obtained by actual measurement on the production site; the mass transfer coefficient γ of component A in the aqueous phase. a The two-phase contact area S is related to the effective volume of the mixing chamber of the extraction tank, the flow rate of the two phases, and the stirring speed, and can be obtained by single-tank experiment calculation; the extraction reaction constant Ka of component A can be obtained by 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 simulation results of the model and the actual production value.

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

[0098] Determination of control variable values ​​in the flow rate equation during simulation:

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

[0100] Based on the simulation objectives, control variables such as the extraction aqueous phase flow rate, organic phase flow rate, and aqueous 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 process parameters can be optimized based on simulation analysis of the extraction and separation process:

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

[0103] The initial acidity of the feed solution is also an important process parameter that is set in advance in the 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 acidity of the feed solution, similar to the aqueous phase flow rate and the organic phase flow rate. The set value of the feed solution acidity can be optimized through simulation analysis of different values ​​of aqueous phase acidity in the model.

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

[0105] S5. Use the same data as the simulation to verify the model at the production or experimental site. If the relative error between the model calculation results 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 should be corrected according to the following formula:

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

[0107] Among them: I New For the corrected model-level efficiency coefficient, I Old To correct the efficiency coefficients of the previous model, Vrn V represents the actual amount of the component to be separated in the organic phase effluent from the last stage extraction tank. oan This represents the simulated amount of the component to be separated in the organic phase flowing out of the last stage extraction tank.

[0108] Example 1

[0109] The method of this invention is used to simulate the 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 for the countercurrent extraction separation of gadolinium and samarium in the 4-stage P507 system were determined as follows: A content in the feed solution, B content in the feed solution, extraction aqueous phase flow rate, P507 content in the organic phase, extraction organic phase flow rate, A content in the aqueous phase of the 1st-4th stage extraction tank, B content in the aqueous phase of the 1st-4th stage extraction tank, A content in the organic phase of the 1st-4th stage extraction tank, B content in the organic phase of the 1st-4th stage extraction tank, free extractant content in the organic phase of the 1st-4th stage extraction tank, A extraction reaction equilibrium constant, B extraction reaction equilibrium constant, aqueous phase acidity, effective volume of the extraction tank, A mass transfer coefficient in the aqueous phase, B mass transfer coefficient in the aqueous phase, and contact area between the two phases.

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

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

[0113] (1) The effective volume T of the extraction tank was measured to be 0.6 and the contact area S between the two phases was 0.2. The mass transfer coefficient γ of Gd in the aqueous phase was measured experimentally. a Given that the gadolinium-Gd extraction reaction constant Ka is equal to 0.15, the stage efficiency coefficient I is taken as 0.9, and the organic phase Gd flow rate equation for 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) Equations for the Gd flow rate of the water phase in each tank:

[0116] Rwa1 = -Roa1;

[0117] Rwa2 = -Roa2;

[0118] Rwa3 = -Roa3;

[0119] (3) The mass transfer coefficient γ of Sm in the aqueous phase was measured by experiments. a Given that the Sm extraction reaction constant Ka is equal to 0.13, the stage efficiency coefficient I is taken as 0.9, and the Sm flow rate equation for the organic phase in each tank can be obtained as follows:

[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) Equations for the Gd flow rate of the water phase in each tank:

[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 verified using experimental data from the countercurrent extraction separation of gadolinium and samarium using a 4-stage P507 system. If the relative error between the model simulation results and the experimental data was 2.6% < 5%, it indicates that the constructed simulation model for the countercurrent extraction separation of gadolinium and samarium using a 4-stage P507 system is effective.

[0132] Example 2

[0133] Using the method of this invention, the countercurrent extraction and separation process of gadolinium and samarium in a 4-stage P507 system was simulated with different flow ratios (organic phase flow rate / aqueous phase flow rate). The simulation results are shown in the table below:

[0134]

[0135] The simulation results above show that, in the countercurrent extraction process of gadolinium-sammarium separation in the 4-stage P507 system, the separation coefficient (gadolinium partition ratio / sammarium partition ratio) is the smallest when the flow ratio is selected as the control parameter. That is, under the condition that other extraction reaction conditions are determined, the optimal value of the flow ratio is 12.

[0136] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method of simulation of an acid extractant countercurrent cascade extraction separation process, characterized in that, The method comprises the following steps: S1, establishing an n-stage extraction tank model, wherein 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, the aqueous phase containing the extracted component flows from the n-stage extraction tank to the first-stage extraction tank, and a causal relationship diagram of the acid extractant countercurrent multi-stage extraction system is drawn according to the influence relationship between the main variables in the acid extractant countercurrent multi-stage extraction process in the n-stage extraction tank model; S2, on the basis of the causal relationship diagram of the acid extractant countercurrent multi-stage extraction system, a flow rate diagram of the acid extractant countercurrent multi-stage extraction system is drawn according to the change of the mass of the separated component in the organic phase and the aqueous phase in each extraction tank after the extraction reaction; S3, according to the acid extractant extraction reaction equilibrium equation, the flow rate equation of each flow rate in the flow rate diagram of the acid extractant countercurrent multi-stage extraction system is determined, and the simulation model of the acid extractant countercurrent multi-stage extraction is constructed; S4, setting the simulation step of the simulation model, and assigning values to the control variables in the simulation model according to the corresponding data of the simulated scene; S5, model verification is carried out in the production site or the experimental site by using the same data as the simulation, and when the relative error between the model calculation result and the actual production or experimental data is less than 5%, it is indicated that the constructed acid extractant countercurrent multi-stage 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 ] where: I New is the modified model stage efficiency coefficient, I Old is the unmodified model stage efficiency coefficient, V rn is the actual value of the amount of the component to be separated in the organic phase flowing out of the last stage of the extraction column, V oan is the simulated value of the amount of the component to be separated in the organic phase flowing out of the last stage of the extraction column.

2. The method according to claim 1, characterized in that, In step S1, the main variables are the concentration of the extracted component in the aqueous phase, the concentration of the free extractant and the concentration of the extracted component in the organic phase in each extraction tank; In the causal relationship diagram of the acid extractant countercurrent multi-stage extraction system, the concentration of the extracted component in the organic phase in the same extraction tank affects the concentration of the extracted component in the aqueous phase and the concentration of the free extractant, and the concentration of the extracted component in the aqueous phase affects the concentration of the free extractant; Between different stages of extraction tanks, the concentration of the extracted component in the organic phase of the i-stage extraction tank is affected by the concentration of the extracted component in the organic phase and the concentration of the free extractant in the i-1-stage extraction tank, and the concentration of the extracted component in the aqueous phase in the i+1-stage extraction tank; The concentration of the extracted component in the aqueous phase in the i-stage extraction tank is affected by the concentration of the extracted component in the aqueous phase in the i+1-stage extraction tank.

3. The method according to claim 2, characterized in that, The concentration of the extracted component in the organic phase is also affected by the acidity of the aqueous phase, the flow ratio of the liquid and the extraction reaction constant.

4. The method of claim 1, wherein the acid extractant countercurrent cascade extraction process simulation method is characterized by, In step S2, the flow rate diagram of the acid extractant countercurrent multi-stage extraction system is to establish the flow rate relationship of the separated component in the aqueous phase, the flow rate relationship of the separated component in the organic phase and the flow rate relationship of the extractant in each extraction tank, wherein: The flow rate relationship of the separated component in the aqueous phase is the flow rate of the separated component in the aqueous phase between the i-stage extraction tank and the i-1-stage extraction tank; The flow rate relationship of the separated component in the organic phase is the flow rate of the separated component in the organic phase between the i-1-stage extraction tank and the i-stage extraction tank; The flow rate relationship of the extractant is the flow rate of the free extractant between the i-stage extraction tank and the i-1-stage extraction tank.

5. The method according to claim 4, characterized in that, The separated component is two components which are extracted by the extractant at the same time, and both of the two components are any one of metal elements.

6. The method of claim 1, wherein the acid extractant countercurrent multistage extraction process simulation method is characterized by, In the flow rate diagram of the acid extractant countercurrent cascade extraction system in step S3, the two components are named A and B, and the flow rate relationship is water phase A flow rate, water phase B flow rate, organic phase A flow rate, organic phase B flow rate, and extractant flow rate. The flow rate equations of each flow rate are as follows: Roa i = [T / (Lo + Lw)] x γ a x S x {Vwa i+1 - [(Ka x C i-1 3 x Rwa i+1 ) / Pw 3 ] x I; Rwa i = -Roa i ; Rob i = [T / (Lo + Lw)] x γ b x S x {Vwb i+1 - [(Kb x C i-1 3 x Rwb i+1 ) / Pw 3 ] x I; Rwb i = - Rob i ; Roz i = -3 x (Roa i + Rob i ); where: i is the stage number of the n-stage extraction column, 3≤i≤n-1; Roa i is the organic phase A flow rate between the i-1th stage extraction column and the ith stage extraction column, T is the effective volume of the extraction column, Lo is the organic phase flow rate, Lw is the aqueous phase flow rate, γ a is the mass transfer coefficient of A in the aqueous phase, S is the two-phase contact area, Vwa i+1 is the aqueous phase A content of the ith+1 stage extraction column, Ka is the extraction reaction equilibrium constant of A phase, C i-1 is the free extractant concentration of the organic phase of the i-1th stage extraction column, Rwa i+1 is the aqueous phase A flow rate of the ith+1 stage extraction column, Pw is the aqueous phase acidity, I is the stage efficiency coefficient; Rwa i is the aqueous phase A flow rate between the ith stage extraction column and the i-1th stage extraction column; Rob i is the organic phase B flow rate between the i-1th stage extraction column and the ith stage extraction column, γ b is the mass transfer coefficient of B in the aqueous phase, Vwb i+1 is the aqueous phase B content of the ith+1 stage extraction column, Kb is the extraction reaction equilibrium constant of B, C i-1 is the free extractant concentration of the organic phase of the i-1th stage extraction column, Rwb i+1 is the aqueous phase B flow rate of the ith+1 stage extraction column; Rwb i is the aqueous phase B flow rate between the ith stage extraction column and the i-1th stage extraction column; Roz i is the free extractant flow rate between the i-1th stage extraction column and the ith stage extraction column.

7. A method of simulation of a countercurrent multistage extraction process with an acidic extractant according to claim 6, characterized in that, Determination of the control variable value in the flow rate equation in the simulation: According to the determined component content of the feed liquid to be separated in the simulation scenario, the initial values of the flow variable contents of components A and B in the water phase of the nth stage extraction tank are Vwan and Vwbn, respectively; According to the initial concentration of the organic phase extractant, the initial value of the free extractant content of the first tank is Voz1; The initial values of the flow variable Voa1 and Vob1 of the organic phase components A and B are 0; According to the control variable value set by the simulation target, including the water phase flow rate, the organic phase flow rate, and the water phase acidity, the simulation model is run to simulate the extraction separation process.

8. The method of claim 1, wherein the method is characterized by: Optimization of the values of the water phase flow rate and the organic phase flow rate is performed by simulating the output results of different values of the water phase flow rate and the organic phase flow rate; The water phase acidity P in the extraction process is equal to the initial feed liquid acidity, and the water phase flow rate and the organic phase flow rate are optimized by simulating the analysis of different values of the water phase acidity in the model to set the value of the feed liquid acidity.

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