41results about "Counter-current extraction" patented technology

The invention discloses a method for efficiently extracting phenol from coal tar and primarily separating crude phenol oil, and relates to the technical field of chemical separation. Carrying out multi-stage cross-flow or counter-flow extraction on the extracting agent and the coal tar to obtain a raffinate phase and a high-concentration extraction phase; and mixing the raffinate with condensate at the top of the regeneration device and supplemented fresh water, and recovering residual organic amine through a reverse extraction device to obtain a dephenolized oil product and backwashing water. Mixing and diluting the extract phase with backwashing water, and standing for phase splitting to obtain a high-grade crude phenol oil phase and a low-concentration extract phase; the low-concentration extraction phase absorbs CO2 in the industrial tail gas for acidification to obtain a low-grade crude phenol oil phase and an amine salt aqueous solution; and desorbing the amine salt aqueous solution to obtain a regenerated extraction agent (circularly used for extraction), tower top condensate (circularly used for reverse extraction) and water-containing industrial-grade CO2 gas (recycled or sealed after drying). According to the method, high-efficiency extraction of the phenolic compounds in the coal tar and primary separation of crude carbolic oil are realized by utilizing the extraction performance differences of extraction capacities, selectivity and the like of the extraction agents with different concentrations on the phenolic compounds, and the production economy is improved.

This invention provides a production process for manufacturing metallic magnesium and industrial silicon by decomposing serpentine using the hydrochloric acid method. [Solution] The present invention provides a method for processing serpentine ore as a raw material using a two-stage countercurrent hydrochloric acid leaching process. The wet process steps include storage and filtration of the slurry after ore dressing, two-stage hydrochloric acid leaching under atmospheric pressure, washing and filtration of the silicon slag after leaching, removal of iron and nickel precipitation from the leaching solution, separation, washing and filtration of the obtained iron hydroxide and nickel hydroxide, crystallization and evaporation of the magnesium chloride solution, and production of hydrochloric acid using the gas generated after the thermal decomposition of magnesium chloride. The present invention has developed a serpentine decomposition technology using hydrochloric acid, a metallic magnesium production process using a drying-electrolytic method, and a process for producing industrial silicon by smelting silicon slag in an electric furnace.

A countercurrent extraction device for spinning includes an extraction box containing extraction liquid, and the extraction box is provided with a plurality of partition assemblies, and the extraction box is partitioned into a plurality of extraction chambers by the partition assemblies; each of the partition assemblies includes a first plate and a second plate, two ends of the first plate are fixedly connected to two sidewalls of the extraction box, and a first gap is provided between a lower edge of the first plate and a bottom wall of the extraction box; a lower edge of the second plate is connected to the bottom wall of the extraction box, a second gap is provided between a top edge of the second plate and a top wall of the extraction box, and heights of a plurality of second plates are gradually decreased along a flow direction of the extraction liquid.

The invention discloses a method for recovering ammonium fluoride from semiconductor photovoltaic wastewater. The method comprises the following steps: adjusting pH in a pretreatment stage, and adding sodium citrate to complex metal ions; a composite extraction agent composed of diisooctyl phosphate, trialkyl phosphine oxide and methyl trioctyl ammonium chloride is adopted for multi-stage counter-current extraction; sequentially carrying out washing and two-stage gradient ammonia water reverse extraction to improve the selectivity and inhibit silicon-boron co-dissolution; the strip liquor is subjected to calcium and magnesium salt impurity removal, reduced pressure evaporation, graded cooling crystallization and vacuum drying, an ammonium fluoride product with the purity larger than or equal to 94% and the water content smaller than or equal to 0.5% is finally obtained, the extracting agent can be recycled, mother liquor and washing liquor are recycled, and the process is closed, environmentally friendly, economical and suitable for industrial application.

An extractor apparatus that incorporates an autoclave that defines an interior, which extends along a longitudinal axis between opposite media inlet and discharge ports. Also included is a feed assembly that is coupled to the inlet port to supply media during operation to the interior, which establishes a media bed movable about the longitudinal axis through the interior to the discharge port. Further incorporated is a solvent supply that is coupled to the autoclave proximate the discharge port to establish during operation pressurized solvent cross flow that is directionally opposite the direction of movement of movable bed. An extract port is also included, which is coupled to the autoclave proximate the inlet port to extract cross-flowed solvent from the movable media bed during operation. Further included is a capture assembly that is sealingly coupled to the discharge port and which during operation, captures spent media, and is movable to discharge the spent media. The capture assembly may also extract residual solvent from the spent media, which may be communicated to the interior between the inlet and discharge ports.

The invention relates to the technical field of coffee bean treatment, in particular to low-caffeine treatment equipment and method by combining supercritical CO2 with molecular sieve directional adsorption, and the low-caffeine treatment equipment comprises an extraction kettle, and a fluid circulation mechanism and a treatment tank which are arranged on the left side and the right side of the extraction kettle, the extraction kettle comprises a kettle body which allows CO2 fluid to flow from bottom to top and is used for placing coffee beans, a filter cartridge arranged at the center in the kettle body, and an auger arranged in the filter cartridge. According to the invention, a dynamic circulating extraction structure of coffee beans is constructed by arranging the auger driven by the motor and the filter drum in the extraction kettle, and the coffee beans continuously rise in the filter drum under the lifting action of the auger and are uniformly scattered from the top end, and form countercurrent and dynamic full contact with supercritical CO2 which is introduced from the bottom of the kettle and flows upwards, so that the extraction efficiency of the coffee beans is improved. A traditional static soaking mode is changed, the contact area and updating frequency of coffee beans and a solvent are increased, the single-batch processing time is shortened, and the situation of local excessive extraction or insufficient extraction is avoided.

The invention belongs to the technical field of nitration reaction product separation, and particularly relates to a mixed dinitrobenzene extraction separation process applied to nitration reaction. Through three-section gradient dilution and accurate concentration control, the problem of incomplete separation caused by high solubility of high-concentration sulfuric acid to nitrobenzene is effectively solved, meanwhile, the hidden danger of pipeline blockage caused by dinitro compound crystallization is eliminated, and the production safety and the product purity are remarkably improved. According to the invention, a complete material closed-loop system is established, the extractant-nitrobenzene is directly reused for nitration reaction after deep dehydration and impurity removal, and the waste sulfuric acid is completely returned to a production system for recycling after being treated, so that the utilization rate of raw materials is greatly improved, and the discharge of waste acid is reduced. According to the method, key parameters such as temperature, concentration and flow are monitored in real time, so that the nitration reaction yield is stabilized at 97.2% or above, the operation cycle of the device is effectively prolonged, and reliable technical guarantee is provided for industrial production.

Process for recycling a loaded aromatic capture oil containing polycyclic aromatic hydrocarbons. The invention relates to a process for reprocessing a loaded aromatic capture oil (11) comprising an aromatic capture oil and one or more polycyclic aromatic hydrocarbons, the process being characterized in that it comprises a step of separating said polycyclic aromatic hydrocarbon from the aromatic capture oil, the separation step being carried out by supplying a counter-current continuous contactor (100) with the loaded aromatic capture oil and with supercritical carbon dioxide (23). Figure for the abstract: Fig. 1.

The invention relates to a process for treating a biocrude feedstock obtained from a hydrothermal liquefaction treatment to reduce the content of inorganic compounds, comprising: - a step of diluting the biocrude feedstock with a light organic diluent to obtain a diluted biocrude feedstock; - a step of washing the diluted biocrude feedstock with at least one aqueous solvent, followed by a step of backwashing with a counter-solvent comprising at least one hydrocarbon cut at a specific boiling point, in one or more countercurrent liquid-liquid extraction columns; - a raffinate fractionation step to obtain at least the biocrude feedstock depleted in inorganic compounds and a phase comprising the diluent.

To provide a method for counter-current liquid-liquid extraction in a sub-millimeter conduit.SOLUTION: The method is implemented from an initial liquid drop stream in a conduit. The initial liquid drop stream is constituted of alternating drops of a first liquid (LB) and a second liquid (LNM) less wetting than the first liquid and immiscible with the first liquid, one of the two liquids comprising a component to be extracted toward the other of the two liquids. The method comprises the steps of: (a) applying a first pressure gradient along the conduit to generate a visco-inertial flow displacing a first volume of drop stream according to a first gradient and generating a film of first liquid displaced along an opposite orientation to the first gradient (the film being located between the drops of second liquid and the conduit); (b) stopping the application of the first pressure gradient; (c) applying a second pressure gradient along the conduit, in the opposite orientation to the first pressure gradient applied to generate a viscous-capillary flow displacing a second volume of drop stream; and (d) stopping the application of the second pressure gradient.SELECTED DRAWING: Figure 3

The present invention provides a hydrodynamic-cavitation-based liquid-liquid reactor and a method thereof, and an apparatus. The reactor comprises a chamber A and a chamber B, wherein the chamber A is configured to convey a first fluid so as to make same rotatably enter a cavitation reaction unit in a central region; the chamber B is configured to convey a second fluid so as to make same rotatably enter the cavitation reaction unit to mix with the first fluid; and an axially adjustable flow guide member is provided in the central region to assist with drainage. The present invention achieves high-efficiency mass transfer of multiphase fluids in a controllable cavitation field by means of an innovative dual-tangential reverse feeding structure, adjustable flow guidance and Venturi coupling design, forming reaction intensification through swirling flow impingement, mixing and cavitation collapse; moreover, intelligent regulation and control of a reaction path is achieved by means of the micro-injection of gas and flow field adjustment, thus significantly improving the reaction rate, selectivity and energy efficiency ratio. Thus, the present invention has good engineering adaptability and prospects for large-scale application.

A hydrometallurgical process for the selective recovery of silver from a solid waste material, said solid waste material deriving from waste electrical and electronic equipment and / or from exhausted Ag-based catalysts, comprises the following steps: I) Subjecting said solid material to acid leaching to dissolve said silver by using a leaching solution, wherein said leaching solution is an aqueous solution of sulphuric acid, ferric sulphate and thiourea (H2SO4-Fe2(SO4)3-CH4N2S), said subjecting to acid leaching being carried out at ambient temperature and at atmospheric pressure, in a single stage or in multiple stages; filtering the exiting leaching solution and subjecting the residual solid material to washing with water; wherein said sulphuric acid, said ferric sulphate and said thiourea are contained in said leaching solution at the following concentrations: sulphuric acid 0.1-0.5 M; ferric sulphate 10-40 g / L; thiourea 10-40 g / L; II) Recovering said water used during said washing in said step I, replenishing said water with said sulphuric acid, said ferric sulphate and said thiourea and, when said subjecting to acid leaching is carried out in multiple stages, using said water as a leaching solution in said multiple stages, wherein said replenishing said water comprises adding said sulphuric acid, said ferric sulphate and said thiourea according to the following percentages compared to the dosage thereof in said step I: sulphuric acid 10-50%; ferric sulphate 80-100%; thiourea 25-50%; III) Subjecting said leaching solution exiting from said step I to electrolysis under stirring to recover said silver as metallic silver at the cathode and regenerate said thiourea; recovering said leaching solution at the end of said electrolysis; IV) Replenishing said leaching solution recovered at the end of said electrolysis in said step III con said sulphuric acid, said ferric sulphate and said thiourea, and, after said replenishing, reusing said leaching solution to treat a new solid waste material.

The invention relates to the technical field of tea leaf extraction, in particular to a dynamic countercurrent ultrasonic enhancement device for extracting functional components of tea leaves, which comprises a treatment tank, a cover plate is arranged on the treatment tank, a tea leaf pretreatment assembly is arranged on the cover plate, and the tea leaf pretreatment assembly comprises a lifting tank used for extracting the functional components of the tea leaves, the cover plate is arranged at the top end of the lifting tank and used for sealing, and a through hole is formed in the center of the cover plate. When a rotating motor drives a grinding sheet to rotate, tea leaves located at the top end of a filter plate can be ground and crushed, and in the grinding and crushing process, due to the fact that the tea leaves are stirred by the grinding sheet, the crushed tea leaves can fall into a screening tank through holes in the filter plate in the stirring process to be subjected to secondary screening; the problem that the tea leaves are directly extracted after being ground and crushed into different particle sizes, and the extraction effect is poor is avoided.

A method for preparing metallic magnesium and industrial silicon by decomposing serpentine with hydrochloric acid is provided. Serpentine is used as a raw material, and is processed by a two-stage countercurrent leaching process in a hydrochloric acid system. A hydrometallurgical process is adopted, including beneficiation, wet grinding, slurry storage, filtration, two-stage atmospheric pressure hydrochloric acid leaching, washing and filtration of leached silica slag, iron removal and nickel precipitation from a leachate, separation, washing and filtration of a ferric hydroxide precipitate and a nickel hydroxide precipitate, crystallization and evaporation of a magnesium chloride solution, and hydrochloric acid preparation from a flue gas generated after thermal decomposition of magnesium chloride. The present disclosure develops a process of decomposing serpentine with hydrochloric acid and producing metallic magnesium by a drying-electrolysis method, and a process of producing industrial silicon by smelting silica slag in an electric furnace.

The application discloses a countercurrent extractant, which comprises the following components in a mass ratio: 40-60 of target oil, 10-20 of methyl ethyl ketone, 0.2-0.5 of sodium silicate and 20-30 of water. The application also discloses preparation and application thereof. The application provides an oil extraction process by low-temperature countercurrent extraction, a flotation method for extracting barite minerals from oil-based drilling cuttings, a method for processing oil-based drilling cuttings by using flotation tailings to prepare proppants, and development of high-efficiency extractants and flotation agents. After countercurrent extraction, the oil content of the oil-based drilling cuttings can be reduced to below 0.3%.

The application provides a method for preparing a momordica grosvenori sweet composition from momordica grosvenori and application thereof. The method for extracting the sweet composition from the momordica grosvenori preferably comprises the following steps: ripening of immature momordica grosvenori, juice extraction, pure water extraction, impurity removal, concentration and purification, and the like to obtain the sweet composition. The application also comprises a compound sweetener containing the sweet composition, which can be widely applied in food, beverage, health care product, daily chemical product, and the like. The application controls the contents of mogroside III and mogroside IIe, so that the momordica grosvenori sweet composition has a better taste. In the preparation process of the sweet composition, only pure water is used, and no organic solvent such as ethanol is used, so that the production process is more green and healthy.

An artemisinin continuous gradient forward and reverse flow forward and reverse rotation extraction method belongs to the technical field of artemisinin extraction, and comprises the following steps: enabling an artemisia apiacea material to sequentially pass through a plurality of extraction sections connected in series along a first direction; injecting the extraction solvent along the direction opposite to the overall direction of the material, and controlling by a solvent bridge pipe, so that the solvent sequentially and reversely fills the subsequent sections to form a continuous gradient forward and reverse flow extraction environment in which the solvent flow direction is the same as the material flow direction in part of the sections and opposite to the material flow direction in part of the sections; in the extraction process, materials are stirred in a periodic positive and negative rotation mode, and an ultrasonic field is applied to a specific section for assistance; the device is a special system for implementing the method. According to the method disclosed by the invention, the extraction yield of the artemisinin is remarkably improved through the cooperation of'gradient forward and reverse flow design ', 'dynamic forward and reverse rotation stirring' and'ultrasonic assistance ', the extraction time is shortened to about 2 hours, and the production efficiency is greatly improved.

The invention relates to a continuous countercurrent ultrasonic vortex extraction system and a method for extracting hesperetin from citrus peel, and the continuous countercurrent ultrasonic vortex extraction system comprises a raw material pretreatment unit used for crushing a dried citrus peel raw material; an inlet of the slurry blending tank is connected with the raw material pretreatment unit, the slurry blending tank is used for receiving the crushed raw materials and mixing the crushed raw materials with a solvent to prepare slurry, and an outlet of the slurry blending tank is connected with a first conveying pump. The ultrasonic vortex tube type reactor is of a vertical or inclined tubular structure, and the ultrasonic transducers are uniformly distributed in the axial direction of the ultrasonic vortex tube type reactor. According to the technical scheme, the solvent consumption is reduced through high solvent utilization rate brought by the countercurrent process. Therefore, the production cost is reduced, and the environmental protection pressure of subsequent waste liquid treatment is greatly reduced; the method has significant progress in the aspects of extraction efficiency and solvent saving, can be suitable for large-scale continuous automatic production, and has advancement and industrial application value.

The application provides a method for preparing high-purity hafnium tetrachloride by wet extraction separation, and steps include: taking hafnium alloy waste as raw material, stirring and leaching by using HNO3 and HF mixed acid, then adding thioacetamide, adjusting pH to 4-5, and filtering after stirring; a composite extraction agent is obtained by compounding tributyl phosphate, trioctylphosphine oxide and sulfonated kerosene, and a homogeneous organic phase is formed by stirring and mixing; in a hydrochloric acid medium, the volume ratio of the organic phase to the aqueous phase is controlled to be 2.5-3.5:1, three-stage countercurrent extraction is carried out, and phase separation is carried out after standing; the organic phase after extraction passes through an adsorption column filled with imino-diacetic acid modified silica gel; hydrochloric acid solution is used for back extraction, then vacuum evaporation concentration is carried out, and hafnium tetrachloride is obtained after cooling crystallization and dehydration. In the application, the hafnium-zirconium separation efficiency in the hafnium tetrachloride preparation process is improved, and the problem of too high zirconium and hafnium impurity content in the product is solved.

The present application belongs to the technical field of battery separator extraction equipment, which comprises an extraction tank, an internal boundary of which defines a containing space; a partition plate arranged in the extraction tank to separate the containing space into an extraction space and a recovery space; a roller group arranged in the extraction space; a liquid inlet arranged at one end of the extraction tank; a baffle mechanism arranged at one end of the partition plate to adjust the overflow width of the extraction liquid; a detection system arranged on the extraction tank to measure the physical properties of the extraction liquid; a temperature control device arranged in the extraction tank to adjust the physical properties of the extraction liquid; and a processor connected with the baffle mechanism and the detection system respectively to receive the overflow width and the physical properties and calculate the Reynolds number of the extraction liquid.

The present invention relates to a process for the selective extraction of a salt to be extracted from a brine to be treated containing the said salt to be extracted, characterized in that: the brine to be treated (S1) is sent to an initial extraction stirrer-mixer (1a) into which a liquid hydrophobic organic phase is also introduced, the said brine and the said liquid hydrophobic organic phase are mixed in the said initial extraction stirrer-mixer (1a), and the mixture is sent to an initial decanter-separator (1d, 1dc), in order to obtain: a brine from which salt to be extracted has been removed; and an organic phase loaded with salt to be extracted; the brine from which the salt to be extracted has been removed is recovered; the organic phase loaded with salt to be extracted is sent to an initial washing stirrer-mixer-decanter-centrifugal separator (5a, 5dc or 7a, 7dc), in order to obtain a purified organic phase loaded with salt to be extracted, which is sent to a so-called “organic” heat exchanger (1e) in which it is heated before being sent to a so-called initial “regeneration” column (1c; 2c), in which a countercurrent exchange is carried out with hot water at a higher temperature than that of the initial brine, in order to obtain: a water containing the salt to be extracted; and a regenerated organic phase, having lost the salt to be extracted; the regenerated organic phase is recycled to the initial extraction stirrer-mixer (1a).

The invention relates to a process, method and devices for recovery of products from a feedstock such as an organic, non-organic or biodynamic feedstock. The products include consumables such as high nutrition foods, nutraceuticals and bioactive compounds and / or non-consumables such as energy and synfuels. The invention typically includes real-time process optimisation. The devices include a counter current diffusion extractor and a decorticator for deriving useful products from a feedstock, optionally for consumption in further processing.

The invention relates to the technical field of food engineering, and particularly discloses an efficient low-temperature extraction system and process for red beet juice. The process comprises the following steps: cleaning fresh red beet with saline water, crushing after cleaning, and adding purified water in the crushing process to obtain vegetable pulp; adding a compound enzyme agent into the vegetable pulp to obtain enzyme-treated pulp, and breaking walls of the enzyme-treated pulp to obtain wall-broken pulp; carrying out three-stage counter-current extraction on the wall-broken slurry; and centrifuging the first-stage extraction liquid, enabling the centrifugal clear liquid to pass through a filter membrane with the pore diameter of 0.1-0.3 mu m, and sterilizing to obtain the red beet juice. The method can improve the juice yield of the red beet juice under the condition of reducing oxidation of the red beet juice.

The invention provides a low-temperature continuous extraction process of eurycoma longifolia, and belongs to the technical field of extraction of effective components of plants. The extraction process comprises the following steps: (1) carrying out low-temperature cavitation pretreatment on an eurycoma longifolia raw material; (2) feeding the pretreated raw material into a four-stage continuous counter-current extraction device, extracting with a mixed solvent at the temperature of 25-50 DEG C, and setting a temperature gradient in the four-stage continuous counter-current extraction device along the advancing direction of the raw material; and (3) carrying out solid-liquid separation on the extract liquor from the extraction device, and carrying out vacuum concentration on the separated liquid phase to obtain the eurycomanone extract. The whole process is operated at low temperature, the continuous production mode obviously improves the extraction efficiency, reduces the solvent dosage and energy consumption, greatly improves the extraction rate of eurycomanone and the product stability, and is suitable for industrial large-scale production.

TITLE: Countercurrent liquid-liquid extraction process in a submillimeter conduit The invention relates to a countercurrent liquid-liquid extraction process in a submillimeter conduit, the process comprising the following steps implemented from an initial train of liquid drops in the conduit, said train being composed of an alternation of drops of a first liquid (LM) and a second liquid (LNM) less wetting than the first liquid and immiscible with the first liquid, one of the two liquids having a component to be extracted towards the other of the two liquids: a) apply a first pressure gradient along the conduit so as to generate a visco-inertial flow displacing a first volume of drop train according to said first gradient and generating a film of first liquid having moved in the opposite direction to said first gradient, the film being located between the drops of second liquid and the conduit;b) stop the application of the first pressure gradient; c) apply a second pressure gradient along the conduit, in the opposite direction to the first pressure gradient applied in step a), so as to generate a visco-capillary flow displacing a second volume of droplet train along said second gradient; and d) stop the application of the second pressure gradient. Figure for the abbreviation: Figure 3;

The invention relates to a counter-current liquid-liquid extraction process in a submillimeter conduit, the process comprising the following steps implemented from an initial train of liquid drops in the conduit, said train being composed of an alternation of drops of a first liquid (LM) and a second liquid (LNM) less wetting than the first liquid and immiscible with the first liquid, one of the two liquids having a component to be extracted towards the other of the two liquids: a) apply a first pressure gradient along the conduit so as to generate a visco-inertial flow displacing a first volume of drop train along said first gradient and generating a film of first liquid having moved in the opposite direction to said first gradient, the film being located between the drops of second liquid and the conduit; b) stop the application of the first pressure gradient;c) apply a second pressure gradient along the conduit, in the opposite direction to the first pressure gradient applied in step a) so as to generate a visco-capillary flow moving a second volume of droplet train along said second gradient; and d) stop the application of the second pressure gradient.

The invention relates to a method for reprocessing a loaded captured aromatic oil (11) comprising a captured aromatic oil and one or more polycyclic aromatic hydrocarbons, the method being characterised in that it comprises a step of separating the polycyclic aromatic hydrocarbon from the captured aromatic oil, the separation step being carried out by supplying a continuous counter-current contactor (100) with the loaded captured aromatic oil and with carbon dioxide in the supercritical state (23).

The invention discloses high-purity electronic-grade n-butyl acetate and a purification method thereof, and the purification method comprises the following steps: selecting industrial-grade superior n-butyl acetate as a raw material, taking deionized water or ultrapure water as extract liquor, and removing anions and metal impurities in the n-butyl acetate through a three-stage countercurrent centrifugal extraction technology; feeding the n-butyl acetate subjected to centrifugal extraction into a rectifying tower, and removing redundant moisture in the n-butyl acetate by using a vacuum rectification method; the product passing through the vacuum distillation dehydration system is subjected to deep filtration treatment through a precise filter element, a high-purity electronic-grade n-butyl acetate product is obtained, the purity of n-butyl acetate obtained through the steps is not smaller than 99.95%, the content of each metal element and each anion in n-butyl acetate is not larger than 0.1 ppb, and the content of each metal element and each anion in n-butyl acetate is not larger than 0.1 ppb. The content of the water molecules in the n-butyl acetate is not more than 50ppm, and the content of particles with the particle size not less than 0.5 mu m in the n-butyl acetate is less than 10 / ml.

The invention provides an adiponitrile refining desalting method and a system thereof, and relates to the technical field of adiponitrile refining. According to the method, through multi-stage cooperation of extraction, water washing, solid-liquid separation, back extraction and combination and phase separation, auxiliary salt is efficiently removed under the mild condition, and the total desalting rate exceeds 99.9%; by means of the optimized process sequence, equipment blockage and product pollution caused by decomposition of the catalyst in water are effectively avoided; and residual nitrile compounds in the water phase are recovered by virtue of a back extraction step, so that the total yield is greater than 99%. The whole process does not need high-temperature or high-vacuum operation, so that the problems of thermal decomposition and coking of adiponitrile in the traditional distillation process are fundamentally avoided, the energy consumption and the equipment investment are remarkably reduced, and the product purity and the operation stability are improved. The corresponding system is highly matched with the method, the integration degree is high, the process is compact, the targets of efficient desalting and high recovery rate can be stably achieved, and the method is completely suitable for industrial continuous production.

A multi-tower liquid-liquid extraction apparatus having two or more extraction towers arranged in parallel. Each tower has a heavy-liquid supplying port at the top and a heavy-liquid discharging port at the bottom. Additionally, each tower has a light-liquid supplying port at the bottom and a light-liquid discharging port at the top. The heavy-liquid channels of the extraction towers are connected in series. Furthermore, at least two of the extraction towers are connected to respective diaphragm chambers through their respective piping. These diaphragm chambers have a closed space, part of the wall of which is formed by a diaphragm whose volume is changed by an operating drive section. The piping between each extraction tower and its respective diaphragm chamber is equipped with a pressure-regulating chamber and an on / off valve to regulate the internal pressure.