Multi-stage solvent extraction and back extraction process control method

Abstract

The invention relates to the technical field of solvent extraction, in particular to a multi-stage solvent extraction and back extraction process control method which comprises the following steps: mounting a mixing and clarifying tank, and putting an extraction agent and a back extraction agent into the multi-stage mixing and clarifying tank for back extraction; sampling off-line analysis concentration based on the monitoring frequency of the mixing clarification tank, recording the current hanging hammer tension value, and recording the concentration analysis result into a system to draw a curve to obtain the corresponding relationship between the concentration and the tension; and comparing the concentration analysis result based on a pre-input response value, and adjusting the flow of the stripping agent or performing intervention treatment by a technician according to the comparison result. According to the method, by corresponding to daily detection and drawing a concentration and tension corresponding curve, a concentration-tension corresponding relation is expected to be obtained, monitoring of a concentration transition point of an extraction component at a monitoring stage of a reverse extraction section is realized, and a basis is provided for regulating and controlling the flow of a reverse extraction agent to realize the reverse extraction limit and stable control of a tank body.

Description

Technical Field

[0001] The invention relates to the technical field of solvent extraction, and in particular to a method for controlling a multi-stage solvent extraction and stripping process. Background Art

[0002] During the operation of the multi-stage continuous solvent extraction separation production line, after the extraction agent (organic phase) containing the target extraction component is purified, the extraction component needs to be transferred to the aqueous phase through the back extraction process to obtain the target aqueous phase liquid containing the extraction component for further use. The back extraction process usually uses a back extraction agent such as an acid, alkali, or complexing agent that is easy to elute the extraction component. The reaction is rapid, so the back extraction section of the multi-stage continuous solvent extraction separation process usually needs to monitor the reaction limit of the relevant area in a timely manner to find out the direction of the reaction limit change caused by the flow and concentration fluctuations of each participating reactant on the reaction system, and to adjust and control in time to achieve smooth and efficient production operation.

[0003] Stripping agents such as acids, alkalis, and chelating agents used in stripping are usually highly corrosive. There are also some attachments in the reaction chamber. Common potential means such as photoelectric probes, pressure sensors, and automatic sampling devices are difficult to achieve automated monitoring due to factors such as corrosion and interference from attachments.

[0004] Currently, the main monitoring method is to manually take samples at regular intervals and send them to the analysis station for offline analysis of the concentration of the aqueous phase extraction components. The technicians then determine the direction of the reaction limit change based on the concentration value and issue control instructions to stabilize production. The entire process has a long result acquisition cycle, making it difficult to detect and deal with abnormal problems in real time. Summary of the invention

[0005] The purpose of the present invention is to provide a method for controlling a multi-stage solvent extraction and stripping process, aiming to solve the problem that manual timed sampling and sending to an analysis post for content analysis of aqueous phase extraction components has a long acquisition cycle and is difficult to achieve real-time discovery and disposal of abnormalities.

[0006] To achieve the above object, the present invention provides a method for controlling a multi-stage solvent extraction and stripping process, comprising the following steps:

[0007] Install a mixing and settling tank, and put an extractant and a stripping agent into the mixing and settling tank for stripping;

[0008] Install a mixing and settling tank, and put an extractant and a stripping agent into the mixing and settling tank for stripping;

[0009] Based on the monitoring frequency of the mixing and clarifying tank, sampling is performed offline to analyze the concentration, and the value of the hanging hammer tension at that time is recorded. The concentration analysis result is recorded into the system to draw a curve to obtain the corresponding relationship between concentration and tension;

[0010] The concentration analysis result is compared based on the pre-input response value, and the stripping agent flow rate is adjusted or a technician intervenes in the process according to the comparison result.

[0011] The stripping agent is an acid, alkali and complexing agent such as hydrochloric acid, nitric acid, sodium hydroxide and EDTA. The pre-input response value includes a normal value, a low value, a high value and an alarm value.

[0012] The normal value fluctuation range is 20-80% of the water phase concentration of the target extraction component, and the alarm value fluctuation range is 0-10% and 90-100% of the water phase concentration of the target extraction component.

[0013] The mixing and clarifying tank includes a remote information receiver, an audible and visual alarm, a deformation spring, a pressure transmitter, a computer processor, an agitator, a pulley, a hanging hammer, a traction rope, an extraction tank mixing chamber and an extraction tank clarifying chamber;

[0014] The mixing and clarifying tank comprises a remote information receiver, an audible and visual alarm, a deformation spring, a pressure transmitter, a computer processor, an agitator, a pulley, a hanging hammer, a traction rope, an extraction tank mixing chamber and an extraction tank clarifying chamber;

[0015] The extraction tank mixing chamber is arranged on one side of the extraction tank clarifying chamber, the agitator is arranged on the top of the extraction tank mixing chamber, the pulleys are respectively arranged on one side of the extraction tank mixing chamber and the extraction tank clarifying chamber, the traction rope is arranged on one side of the pulley, the pendulum is fixedly connected to the traction rope and is located in the extraction tank clarifying chamber, the deformation spring is fixedly connected to the traction rope and is located at any position between the traction rope and the pendulum, the pressure transmitter is fixedly connected to the deformation spring and is located on the side of the deformation spring away from the traction rope, and the computer processor is respectively connected to the remote information receiver, the sound and light alarm and the pressure transmitter.

[0016] The invention discloses a method for controlling a multi-stage solvent extraction and stripping process, wherein a mixing and settling tank is installed, and an extractant and a stripping agent are put into the mixing and settling tank for stripping; the concentration change of the extraction component in the water phase of the settling chamber during the stripping process corresponds to the change in the buoyancy of the suspended hammer in the water phase immersed at the position, causing the change in the tension value of the suspended hammer; the concentration is sampled and analyzed offline by the original offline monitoring frequency, and the suspension hammer tension value at that time is recorded, and the concentration analysis result is recorded in the system to draw a curve to obtain the corresponding relationship between concentration and tension; the concentration value is compared based on the pre-input response value, and a response is made according to the comparison result, and a stripping agent flow control signal or an alarm technician is intervened to realize automatic control. The method draws a concentration and tension corresponding curve corresponding to daily detection, so as to obtain a concentration-tension corresponding relationship, and provides a basis for adjusting the stripping agent flow to realize the stripping limit and stable control of the tank body by monitoring the concentration transition point of the extraction component in the water phase of the stripping section, so as to solve the problem that the concentration of the extraction component is analyzed offline by manual timing sampling and sent to the analysis post, and the acquisition cycle is long, and it is difficult to realize real-time discovery and disposal of abnormalities. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The present invention provides a schematic diagram of the principle of a multi-stage solvent extraction and stripping process.

[0019] Figure 2 It is a schematic diagram of the connection of a multi-stage solvent extraction, stripping, mixing and clarification tank provided by the present invention.

[0020] Figure 3 The present invention provides a schematic diagram of the arrangement of a reaction monitoring stage device and a control circuit for a multi-stage solvent extraction and stripping process.

[0021] Figure 4 The present invention provides a flow chart of a method for controlling a multi-stage solvent extraction and stripping process.

[0022] In the figure: 1-remote information receiver, 2-sound and light alarm, 3-deformation spring, 4-pressure transmitter, 5-computer processor, 6-agitator, 7-pulley, 8-hammer, 9-extraction tank clarification chamber, 10-traction rope, 11-extraction tank mixing chamber, 12-multi-stage mixing and clarification tank first stage, 13-multi-stage mixing and clarification tank monitoring stage, 14-multi-stage mixing and clarification tank final stage, 15-flow measurement and adjustment feedback device. DETAILED DESCRIPTION

[0023] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0024] See also Figures 1 to 4 The present invention provides a method for controlling a multi-stage solvent extraction and stripping process, comprising the following steps:

[0025] S1 installs a mixing and settling tank, and puts an extractant and a stripping agent into the mixing and settling tank for stripping;

[0026] Specifically, the mixing and settling tank includes a remote information receiver 1, an audible and visual alarm 2, a deformation spring 3, a pressure transmitter 4, a computer processor 5, an agitator 6, a pulley 7, a hanging hammer 8, an extraction tank clarification chamber 9, a traction rope 10, an extraction tank mixing chamber 11, a multi-stage mixing and settling tank first stage 12, a multi-stage mixing and settling tank monitoring stage 13, a multi-stage mixing and settling tank final stage 14 and a flow measurement and adjustment feedback device 15;

[0027] The extractant to be stripped (organic phase) containing the extraction components enters the extraction tank mixing chamber 11 of the first stage 12 of the multi-stage mixing and settling tank and participates in the reaction step by step until the reaction is complete and the blank extractant overflows from the last stage 14 of the multi-stage mixing and settling tank; the stripping liquid enters the extraction tank mixing chamber 11 of the last stage 13 of the multi-stage mixing and settling tank at a set flow rate through the flow measurement and adjustment feedback device 15 and participates in the reaction step by step until the reaction is complete and the aqueous phase liquid containing the target extraction components overflows from the first stage 12 of the multi-stage mixing and settling tank.

[0028] In each stage of the multi-stage mixing and settling tank where the stripping section is located, the extraction tank mixing chamber 11 is arranged on one side of the extraction tank settling chamber 9, and the agitator 6 is arranged on the top of the extraction tank mixing chamber 11; the organic phase and the aqueous phase to be reacted enter the extraction tank mixing chamber 11 through the flow port and are mixed and reacted by the agitator 6 to form a mixed liquid phase, and the mixed liquid phase flows into the extraction tank settling chamber 9 of this stage to be slowly clarified to obtain an organic phase and an aqueous phase, and the organic phase enters the next stage mixing chamber through the overflow port to continue the reaction until the last stage flows out, and the aqueous phase enters the previous stage mixing chamber through the overflow port to continue the reaction until the first stage flows out.

[0029] The pulley 7 is installed on the multi-stage mixing and clarifying tank monitoring stage 13 and is respectively arranged on one side of the extraction tank mixing chamber 11 and the extraction tank clarifying chamber 9. The pendulum 8 is fixedly connected to the traction rope 10 and is located in the extraction tank clarifying chamber 9 of the multi-stage mixing and clarifying tank monitoring stage 13 and immersed in the water phase to be monitored. The traction rope 10 is arranged on one side of the pulley 7. The deformation spring 3 is fixedly connected to the traction rope 10 and is located at any position between the traction rope 10 and the pendulum 8. The pressure transmitter 4 is fixedly connected to the deformation spring 3 and is located on the side of the deformation spring 3 away from the traction rope 10. The computer processor 5 is respectively connected to the remote information receiver 1, the sound and light alarm 2, the pressure transmitter 4 and the flow measurement and adjustment feedback device 15.

[0030] S2 takes samples based on the monitoring frequency of the mixing and clarifying tank for offline concentration analysis, and records the tensile force value of the pendulum 8 at that time, and records the concentration analysis results into the system to draw a curve to obtain the corresponding relationship between concentration and tensile force;

[0031] Specifically, the stripping process is mainly a process in which the extractant (organic phase) containing the extraction component reacts with the stripping agent (aqueous phase) to transfer the extraction component to the aqueous phase. Taking the acidic extractant RH, A+ as the extraction component and HCl as the stripping agent as an example, the stripping process mainly undergoes the following reactions:

[0032] R-A+HCl→R-H+ACl

[0033] Its operation and control principle are detailed Figure 1 As shown:

[0034] Usually, the molecular weight of A+ is greater than that of H+ (this component of common stripping agents is usually hydrogen and low molecular weight alkali metals such as ammonium, potassium, and sodium), so its density will increase synchronously with the increase of the content of the extracted components during the process of transferring the extracted components to the water phase. Therefore, the buoyancy change caused by the change in the density of the water phase in the reaction area can be used to monitor the change in the content of the stripping components, and then determine the direction of the change in the reaction limit and issue a stripping agent flow control instruction to stabilize the content of the stripping components within a reasonable range and stabilize production operation.

[0035] In the multi-stage mixing and clarifying tank monitoring stage 13, when the concentration of the aqueous phase extraction component to be monitored in the extraction tank clarifying chamber 9 changes due to the change in the reaction limit, the buoyancy of the pendant 8 also changes, thereby causing the tension caused by the traction rope 10 on the pressure transmitter 4 to change. The pressure transmitter 4 uploads the real-time tension data to the computer processor 5, and the computer processor 5 records the tension data. At the same time, the water phase near the pendant is sampled and the concentration is analyzed offline through the original offline monitoring. The concentration analysis results are recorded in the system and a curve is drawn with the tension data during sampling to obtain the corresponding relationship between concentration and tension. Finally, the tension data can be converted into the concentration data of the aqueous phase to be measured.

[0036] S3 compares the concentration analysis result based on the pre-input response value, and adjusts the stripping agent flow rate or technical personnel intervene in the process according to the comparison result.

[0037] Specifically, the pre-input response value includes a normal value, a low value, a high value and an alarm value. The response action for the low or high value is to issue a control prompt or to issue a control prompt and issue an instruction to the flow measurement and adjustment feedback device 15 to control the flow of the stripping agent. The response action for the alarm value is to issue an alarm to the operator by the sound and light alarm 2 and the remote information receiver 1 so that the operator can intervene to deal with the abnormality as soon as possible. The corresponding response value and response action of the specific measured concentration (represented by the ratio of the measured concentration to the aqueous phase concentration of the target extraction component) are shown in Table 1.

[0038] Table 1

[0039]

[0040]

[0041] In order to better understand the present technical solution, the following embodiments are provided for further explanation:

[0042] Example:

[0043] In the stripping section of the mixed clarification tank with a total of 12 stages, the rare earth lanthanum-loaded organic countercurrent stripping operation is carried out. At the first stage of the stripping section, 100L / min of lanthanum-loaded organic phase containing 0.15mol / L lanthanum is added, and it flows backward step by step to participate in the reaction, and at the same time, the target extraction component lanthanum chloride concentration of 1.5mol / L aqueous phase is produced; at the last stage 12 of the stripping section, 10L / min of hydrochloric acid of a certain concentration is added as a stripping agent, and the stripping agent flows forward step by step to participate in the reaction, and at the same time, all blank organic phases are produced. In order to ensure the normal operation of production, a certain buffer level is reserved in the construction of the tank body. Under normal circumstances, it is necessary to control the third-stage aqueous phase to almost contain no stripping agent and the tenth-stage organic phase to almost contain no lanthanum load to ensure the quality of the lanthanum chloride aqueous phase and the organic stripping effect to obtain blank organic. Because of the characteristics of the reaction system, there are usually relatively fixed levels of about 6 levels from the start of the reaction to the end of the reaction. In the reaction level, the fifth level with intense reaction and strong concentration changes can be found as the concentration monitoring level to monitor the reaction limit. At this level, if Figure 3 Install a pendulum and immerse it in the water phase to be monitored to measure the tension data. At the same time, sample the water phase near the pendulum through the original offline monitoring to analyze the concentration offline. Record the concentration analysis results into the system and draw a curve with the tension data during sampling to obtain the corresponding relationship between concentration and tension. Finally, the tension data can be converted into the concentration data of the water phase to be measured.

[0044] The response values ​​and response actions are pre-entered into the computer processor system as shown in Table 2.

[0045] Table 2

[0046]

[0047]

[0048] The current system monitors the concentration monitoring level 5 water phase and converts the lanthanum chloride concentration to 0.5mol / L, the ratio is between 20-80%, and the system does not act when the concentration is normal; the system is set to automatic. If the reaction zone moves back due to production fluctuations, the system monitors the concentration monitoring level 5 water phase and converts the lanthanum chloride concentration to 1.3mol / L, the ratio is greater than 80% and less than 92%, and the concentration is high. The computer triggers a response prompting a high concentration state and automatically issues a command to the flow measurement and adjustment feedback device to increase the stripping agent flow by 5%, that is, the flow is adjusted to 10*(1+0.05)=10.5L / min. After 1 hour, the system monitors the concentration monitoring level 5 water phase and converts the lanthanum chloride concentration to 1.1mol / L, and again judges that the ratio is between 20-80%, and the system does not act when the concentration is normal; the system is set to manual. If the reaction zone moves forward due to production fluctuations, the system monitors the concentration monitoring level 5 water phase and converts the lanthanum chloride concentration to 0.2mol / L, the ratio is less than 20% and greater than 8%, and the concentration is high. If the concentration is low, the computer terminal triggers a response prompting a low concentration state, and notifies the operator to reduce the flow rate of the extractant. After 1 hour, the system monitors the concentration monitoring level 5 water phase and converts the lanthanum chloride concentration to 0.25 mol / L. It is judged again that the ratio is less than 20% and greater than 8%. If the concentration is still low, the low concentration alarm is triggered to remind the technician to intervene. During the whole process, the system continuously monitors the concentration monitoring level 5 water phase and converts the lanthanum chloride concentration to less than 0.12 mol / L and greater than 0 mol / L or greater than 1.38 mol / L and less than 1.5 mol / L. The computer terminal prompts a low concentration or high alarm state, and the sound and light alarm and remote information receiver simultaneously send an alarm to the operator to remind the technician to intervene. If an abnormality occurs, such as sensor abnormality, the system monitors the concentration monitoring level 5 water phase and converts the lanthanum chloride concentration to less than 0 mol / L or greater than 1.5 mol / L, and the system fails, the computer terminal triggers a response prompting a system failure alarm state, and the sound and light alarm and remote information receiver simultaneously send an alarm to the operator to remind the technician to intervene.

[0049] The above disclosure is only a preferred embodiment of a method for controlling a multi-stage solvent extraction and stripping process of the present invention. Of course, this cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that implementing all or part of the processes of the above embodiment and making equivalent changes according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for controlling a multi-stage solvent extraction stripping process, It is characterized in that The following steps are involved: Install a mixing and settling tank, and put an extractant and a stripping agent into the mixing and settling tank for stripping; Based on the monitoring frequency of the mixing and clarifying tank, sampling is performed offline to analyze the concentration, and the hanging hammer tension value at that time is recorded. The concentration analysis result is recorded into the system to draw a curve to obtain the corresponding relationship between concentration and tension; The concentration analysis result is compared based on the pre-input response value, and the stripping agent flow rate is adjusted or a technician intervenes in the process according to the comparison result.

2. A method for controlling a multi-stage solvent extraction and stripping process as claimed in claim 1, It is characterized in that The stripping agent is hydrochloric acid, nitric acid, sodium hydroxide, EDTA, alkali and complexing agent.

3. A method for controlling a multi-stage solvent extraction and stripping process as claimed in claim 1, It is characterized in that The pre-input response values ​​include normal values, low values, high values ​​and alarm values.

4. A method for controlling a multi-stage solvent extraction and stripping process as claimed in claim 3, It is characterized in that The normal value fluctuation range is 20-80% of the water phase concentration of the target extraction component, and the alarm value fluctuation range is 0-10% and 90-100% of the water phase concentration of the target extraction component.

5. A method for controlling a multi-stage solvent extraction and stripping process as claimed in claim 1, It is characterized in that The mixing and clarifying tank comprises a remote information receiver, an audible and visual alarm, a deformation spring, a pressure transmitter, a computer processor, an agitator, a pulley, a hanging hammer, a traction rope, an extraction tank mixing chamber and an extraction tank clarifying chamber; The extraction tank mixing chamber is arranged on one side of the extraction tank clarifying chamber, the agitator is arranged on the top of the extraction tank mixing chamber, the pulleys are respectively arranged on one side of the extraction tank mixing chamber and the extraction tank clarifying chamber, the traction rope is arranged on one side of the pulley, the pendulum is fixedly connected to the traction rope, and is located in the extraction tank clarifying chamber and immersed in the water phase to be monitored, the deformation spring is fixedly connected to the traction rope, and is located at any position between the traction rope and the pendulum, the pressure transmitter is fixedly connected to the deformation spring, and is located on the side of the deformation spring away from the traction rope, and the computer processor is respectively connected to the remote information receiver, the sound and light alarm and the pressure transmitter.

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