A continuous potassium extraction system in seawater and its application

Abstract

The present invention discloses a system for continuous extraction of potassium from seawater and its application, and belongs to the technical field of potassium resource extraction. The system for continuous extraction of potassium from seawater of the present invention is composed of a positive electrode, a negative electrode, a first cation exchange membrane, a second cation exchange membrane, an anion exchange membrane, a potassium-rich area, a raw material area, an extraction area, a potassium-poor area and an electrode liquid circulation device. The first cation exchange membrane, the anion exchange membrane and the second cation exchange membrane are arranged in a relative parallel manner vertically between the positive electrode and the negative electrode in sequence, and the negative electrode and the positive electrode are separated into a potassium-rich area, a raw material area, an extraction area and a potassium-poor area; the potassium-rich area and the potassium-poor area are connected to form a loop through the electrode liquid circulation device. The system for continuous extraction of potassium from seawater of the present invention can cyclically enrich potassium in seawater and its desalinated concentrated brine, and simultaneously realize the embedding of potassium in the negative electrode and the removal of potassium from the positive electrode, which solves the problem of intermittent potassium extraction of fixed electrodes, and the need to switch between the raw material liquid and the extraction liquid or the fixed electrode for continuous operation, and truly realizes continuous operation.

Description

Technical Field

[0001] The invention belongs to the technical field of potassium resource extraction, and in particular relates to a system for continuous extraction of potassium from seawater and application thereof. Background Art

[0002] Potassium is a basic plant nutrient and one of the three important fertilizer elements (nitrogen, phosphorus and potassium) in the growth and development of plants. The global potassium salt resources are abundant, but the distribution is very uneven. The total potassium reserves in seawater reach 550 trillion tons, which is expected to become a new source of potassium resources, which can alleviate the shortage of potassium resources to a certain extent.

[0003] Existing methods for extracting potassium from seawater mainly include six categories: chemical precipitation, organic solvent extraction, membrane separation, ion exchange, carnallite, and electrochemical methods. Electrochemical potassium extraction has a controllable potassium extraction rate and is considered to have good application prospects. Chinese patent CN113881848A discloses a device and method for graded electrochemical extraction of potassium and lithium from seawater, which extracts potassium ions and lithium ions from seawater by using a potassium ion selective embedding material layer; Chinese patent CN109487294A discloses a method for extracting potassium from seawater or brine, which extracts potassium from seawater by placing a conductive substrate coated with a reducible Prussian blue compound in a cathode chamber as a cathode and a conductive substrate coated with an oxidizable Prussian blue compound in an anode chamber as an anode. However, all of the above schemes use fixed electrodes as potassium ion carriers. During operation, whether the positions of the cathode and anode are kept fixed and the functions of the raw water chamber and the potassium salt chamber are switched, or the functions of the cathode and anode chambers are maintained unchanged and the potassium-intercalated solution in the cathode chamber is retained or discharged and added to seawater, or the positions of the cathode and anode electrodes are exchanged and the electrochemical operation is continued, there are disadvantages that continuous operation requires switching, and the electrode has limited potassium extraction capacity. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a continuous potassium extraction system in seawater and its application.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a system for continuous extraction of potassium from seawater, which comprises a positive electrode, a negative electrode, a first cation exchange membrane, a second cation exchange membrane, an anion exchange membrane, a potassium-rich area, a raw material area, an extraction area, a potassium-poor area and an electrode liquid circulation device;

[0007] The first cation exchange membrane, the anion exchange membrane and the second cation exchange membrane are arranged vertically relatively parallel and spaced in sequence between the positive electrode and the negative electrode, and the negative electrode and the positive electrode are separated into a potassium-rich area, a raw material area, an extraction area and a potassium-poor area in sequence; the negative electrode and the first cation exchange membrane form a potassium-rich area, the first cation exchange membrane and the anion exchange membrane form a raw material area, the anion exchange membrane and the second cation exchange membrane form an extraction area, and the second cation exchange membrane and the positive electrode form a potassium-poor area; the potassium-rich area and the potassium-poor area are connected by an electrode liquid circulation device to form a loop.

[0008] Technical principle: After the seawater is introduced into the raw material area, the potassium ions in the seawater pass through the cation exchange membrane and enter the potassium-rich area. Under the action of the electric driving force, the active substances in the electrode liquid are reduced to a potassium-rich state; the potassium-rich electrode liquid passes through the electrode liquid circulation pump and enters the potassium-poor area, and the potassium ions therein pass through the cation exchange membrane and enter the extraction area. The active substances in the electrode liquid are oxidized to their original state and pass through the electrode liquid circulation pump to enter the potassium-rich area again, thus realizing the system circulation and the purpose of continuous transfer of potassium ions from seawater to the extract; synchronously, the chloride ions in the seawater pass through the anion exchange membrane and enter the extraction area. During the circulation process, the potassium ion concentration in the raw material area gradually decreases, and the potassium ions in the extract are continuously enriched. The raw material area replaces or supplements seawater according to the decrease in potassium ion concentration, and the extraction area is recycled according to the degree of potassium ion enrichment until the potassium ion concentration is close to saturation.

[0009] Preferably, the number of the cation exchange membranes is ≥2, and the number of the anion exchange membranes is ≥1.

[0010] Preferably, the cation exchange membrane is an ion exchange membrane that can only pass cations, including a CMV type cation exchange membrane or a CGU type cation exchange membrane.

[0011] Further preferably, the cation exchange membrane is an ion exchange membrane selective for monovalent cations, including a CHO type cation exchange membrane or a CXP-S type cation exchange membrane, which can selectively permeate potassium ions, thereby reducing the calcium and magnesium content in the electrode solution, thereby reducing the influence of calcium and magnesium on potassium intercalation and deintercalation active substances.

[0012] Preferably, the anion exchange membrane is an ion exchange membrane that can only pass anions, including an AMV type anion exchange membrane or an AGU type anion exchange membrane.

[0013] Further preferably, the anion exchange membrane is an ion exchange membrane selective for monovalent anions, including an ASA type anion exchange membrane or an AXP-D type anion exchange membrane, which can reduce the divalent and multivalent anions in the raw material area from entering the extraction area.

[0014] Preferably, the electrode liquid circulation device includes a first electrode liquid storage tank, a first electrode liquid circulation pump, a second electrode liquid storage tank and a second electrode liquid circulation pump; the top of the first electrode liquid storage tank is connected to the potassium-rich area, and the bottom is connected to the inlet of the first electrode liquid circulation pump; the outlet of the first electrode liquid circulation pump is connected to the potassium-poor area; the top of the second electrode liquid storage tank is connected to the potassium-poor area, and the bottom is connected to the inlet of the second electrode liquid circulation pump; the outlet of the second electrode liquid circulation pump is connected to the potassium-rich area.

[0015] Preferably, the electrode liquid in the electrode liquid circulation device comprises potassium intercalation and deintercalation active substances, conductive carbon black and aqueous electrolyte; and the solvent of the electrode liquid in the electrode liquid circulation device is concentrated brine.

[0016] The present invention adopts an electrode liquid containing potassium intercalation and deintercalation active substances, which can synchronously realize the intercalation and deintercalation of potassium ions and the gain and loss of electrons through a redox process when the system is running. At the same time, the potassium intercalation and deintercalation active substances are in a flowing state, which increases the contact area with seawater and improves the extraction efficiency. The electrode liquid can be regenerated and recycled through the redox reaction; the conductive carbon black plays a conductive role, and the aqueous electrolyte has the advantages of high flame retardancy and safety.

[0017] Preferably, the mass ratio of the potassium intercalation and deintercalation active material, the conductive carbon black and the aqueous electrolyte is (80-90): (5-10): (5-10); and the solid content of the electrode liquid is 5-45%.

[0018] Further preferably, the mass ratio of the potassium intercalation and deintercalation active material, the conductive carbon black and the aqueous electrolyte is (80-85): (5-10): (5-10); and the solid content of the electrode liquid is 15-25%.

[0019] Further preferably, the concentration of the concentrated brine is 0.5-1.0 mol / L.

[0020] Preferably, the potassium embedding and de-embedding active substance is a Prussian blue compound A x M[R(CN)6] 1-y □ y ·nH2O, wherein A is one or more of alkali metals or alkaline earth metals, M is a high-spin transition metal, R is a low-spin transition metal, □ is a [R(CN)6] defect, 0≤x≤2, 0≤y≤1.

[0021] Further preferably, A is one or more of Li, Na, K, Mg, Ca, and Ba; M is one or more of Fe, Mn, Co, Ni, Cu, Zn, and Ti; and R is Fe.

[0022] Further preferably, the potassium embedding and depotassium active substance includes a potassium embedding active substance and a potassium depotassium active substance; the potassium embedding active substance includes one of copper nickel ferrocyanide and copper ferrocyanide, and the electrode liquid containing the potassium embedding active substance is injected into the second electrode liquid storage tank; the potassium depotassium active substance includes one of copper nickel ferrocyanide and copper ferrocyanide, and the electrode liquid containing the potassium depotassium active substance is injected into the first electrode liquid storage tank.

[0023] Preferably, the temperature of the solution in the raw material zone and the extraction zone is 5 to 80° C., and the pH is 2 to 9. Within the above range, the higher the temperature of the solution in the raw material zone and the extraction zone, and the closer the pH is to neutral, the better the extraction effect.

[0024] Further preferably, the temperature of the solution in the raw material zone and the extraction zone is 25-50° C., and the pH is 5-7.5.

[0025] Preferably, the voltage between the positive electrode and the negative electrode is 0.5-2.0V or the current density is ≤100mA / cm 2 The higher the voltage, the better the extraction effect, but the higher the voltage, the higher the energy consumption, and the higher the voltage will cause water electrolysis. The higher the current density, the better the extraction effect, but the higher the current density, the higher the energy consumption, and the water electrolysis will also be aggravated.

[0026] More preferably, the voltage between the positive electrode and the negative electrode is 1.0-2.0 V or the current density is 50-100 mA / cm 2 .

[0027] The present invention also provides a method for extracting potassium using the continuous potassium extraction system in seawater described in the above technical solution, comprising the following steps:

[0028] (1) introducing seawater or concentrated brine after desalination of seawater into the raw material area, and introducing extract into the extraction area;

[0029] (2) injecting electrode liquid into the first electrode liquid storage tank and the second electrode liquid storage tank respectively, and starting the first electrode liquid circulation pump and the second electrode liquid circulation pump;

[0030] (3) Connecting the positive electrode and the negative electrode to a power source, applying voltage, and starting potassium extraction;

[0031] (4) Repeat steps (1) to (3) to complete the continuous extraction of potassium.

[0032] Further preferably, the flow rate of the seawater or the concentrated brine after desalination of seawater is 5 to 10 mL / min.

[0033] Preferably, in step (1), the extract is a solution containing cations.

[0034] Further preferably, the cation-containing solution is a solution containing potassium salt or a mixed solution containing potassium salt and other cationic salts; the concentration of the cation-containing solution is 1 mM-1M, preferably 1 mM-0.5M.

[0035] Further preferably, the potassium salt includes one or more of KCl, K2SO4, and KNO3, and other cationic salts include one or more of NaCl, Na2SO4, NaNO3, NH4Cl, (NH4)2SO4, and NH4NO3.

[0036] Further preferably, the continuous potassium extraction systems in seawater are connected in series to extract potassium from seawater to improve the extraction rate.

[0037] Compared with the prior art, the present invention has the following advantages and technical effects:

[0038] (1) The system for continuous extraction of potassium from seawater provided by the present invention can cyclically enrich potassium in seawater and its concentrated brine after desalination, and simultaneously realize the embedding of potassium in the negative electrode and the removal of potassium from the positive electrode, thereby solving the problems of intermittent potassium extraction at fixed electrodes and the need to switch between raw material liquid and extraction liquid or fixed electrodes during continuous operation. The device has a simple structure, truly realizes continuous operation, the whole process can be automatically operated, has good cycle stability, high resource recovery rate, no pollutant discharge, and is easy to mass produce.

[0039] (2) The continuous potassium extraction system in seawater provided by the present invention can increase the raw material processing capacity and improve the extraction efficiency through series connection to achieve mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0041] Figure 1 A schematic diagram of the structure of a system for continuous extraction of potassium from seawater provided in Example 1 of the present invention;

[0042] Among them, the first electrode liquid storage tank 1-1; the second electrode liquid storage tank 2-2; the first electrode liquid circulation pump 2-1; the second electrode liquid circulation pump 1-2; the negative electrode 3; the positive electrode 4; the first cation exchange membrane 5; the anion exchange membrane 6; the second cation exchange membrane 7; the potassium-rich area 8; the raw material area 9; the extraction area 10; the potassium-poor area 11;

[0043] Figure 2 This is a working principle diagram of the continuous potassium extraction system in seawater provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] In the following examples, the cation exchange membrane is a CHO type cation exchange membrane, and the anion exchange membrane is an ASA type anion exchange membrane;

[0047] Seawater was obtained from the coastal area of ​​Tianjin Binhai New Area. + The ion concentration is about 390 mg / L;

[0048] Desalinated brine is the brine obtained by concentrating seawater through reverse osmosis. + The concentration is about 780mg / L;

[0049] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0050] Example 1

[0051] A continuous potassium extraction system from seawater, the structural diagram is shown in Figure 1 , consisting of a positive electrode 4, a negative electrode 3, a first cation exchange membrane 5, a second cation exchange membrane 7, an anion exchange membrane 6, a potassium-rich area 8, a raw material area 9, an extraction area 10, a potassium-poor area 11 and an electrode liquid circulation device;

[0052] The first cation exchange membrane 5, the anion exchange membrane 6, and the second cation exchange membrane 7 are arranged in parallel and spaced apart in sequence between the positive electrode 4 and the negative electrode 3 in the vertical direction, and the positive electrode 4 and the negative electrode 3 are separated into a potassium-rich area 8, a raw material area 9, an extraction area 10, and a potassium-poor area 11 in sequence, wherein the potassium-rich area 8 is formed between the negative electrode 3 and the first cation exchange membrane 5, the raw material area 9 is formed between the first cation exchange membrane 5 and the anion exchange membrane 6, the extraction area 10 is formed between the anion exchange membrane 6 and the second cation exchange membrane 7, and the potassium-poor area 11 is formed between the second cation exchange membrane 7 and the positive electrode 4; the potassium-rich area 8 and the potassium-poor area 11 are connected to form a loop through an electrode liquid circulation device;

[0053] The electrode liquid circulation device is composed of a first electrode liquid storage tank 1-1, a first electrode liquid circulation pump 2-1, a second electrode liquid storage tank 2-2 and a second electrode liquid circulation pump 1-2. The top of the first electrode liquid storage tank 1-1 is connected to the potassium-rich area 8, and the bottom is connected to the inlet of the first electrode liquid circulation pump 2-1; the outlet of the first electrode liquid circulation pump 2-1 is connected to the potassium-poor area 11; the top of the second electrode liquid storage tank 2-2 is connected to the potassium-poor area 11, and the bottom is connected to the inlet of the second electrode liquid circulation pump 1-2; the outlet of the second electrode liquid circulation pump 1-2 is connected to the potassium-rich area 8.

[0054] Figure 2 This is a working principle diagram of the continuous potassium extraction system from seawater provided in Example 1 of the present invention. Figure 2 It can be seen that after the seawater is introduced into the raw material area, the K + The electrolyte enters the potassium-rich zone through the first cation exchange membrane and then enters the first electrode liquid storage tank, where the active substances in the electrode liquid are reduced to a potassium-rich state. After that, the potassium-rich electrode liquid passes through the first electrode liquid circulation pump and enters the potassium-poor zone. + Passing through the second cation exchange membrane into the extraction zone, the active substances in the electrode liquid are oxidized to their original state and enter the potassium-rich zone again through the electrode liquid circulation pump, thus realizing system circulation and achieving the purpose of continuous transfer of potassium ions from seawater to the extraction solution; synchronously, the chloride ions in the seawater pass through the anion exchange membrane into the extraction zone.

[0055] Example 2

[0056] A method for extracting potassium using the continuous potassium extraction system in seawater in Example 1:

[0057] (1) Seawater is introduced into the raw material zone 9 at a rate of 5 mL / min, and a 0.5 M KCl solution is introduced into the extraction zone 10 at the same time. The temperature of the solutions in the raw material zone 9 and the extraction zone 10 are both 25°C, and the pH is both 7.2;

[0058] (2) Mix the potassium embedding active material (copper ferrocyanide), conductive carbon black and aqueous electrolyte in a mass ratio of 85:10:5, then add them to 1 mol / L concentrated brine and mix them to obtain a potassium-poor electrode liquid with a solid content of 20%; Mix the potassium-depleting active material (copper ferrocyanide), conductive carbon black and aqueous electrolyte in a mass ratio of 85:10:5, then add them to 1 mol / L concentrated brine and mix them to obtain a potassium-rich electrode liquid with a solid content of 20%; Inject the potassium-poor electrode liquid into the second electrode liquid storage tank 2-2, inject the potassium-rich electrode liquid into the first electrode liquid storage tank 1-1, and start the first electrode liquid circulation pump 2-1 and the second electrode liquid circulation pump 1-2;

[0059] (3) The positive electrode 4 and the negative electrode 3 were connected to a power supply, and a voltage of 1.0 V was applied to start the extraction of potassium. The current gradually decreased. After 5 minutes without significant change, the power supply was turned off to end the extraction. The potassium ion extraction rate was calculated to be 58.6%.

[0060] Example 3

[0061] A method for extracting potassium using the continuous potassium extraction system in seawater in Example 1, wherein two continuous potassium extraction systems in seawater are connected in series, namely a first system and a second system:

[0062] (1) Seawater is introduced into the raw material zone 9 of the first system at a rate of 5 mL / min, and a 0.5 M KCl solution is introduced into the extraction zone 10 of the first system at the same time. The temperature of the solutions in the raw material zone 9 and the extraction zone 10 are both 25° C., and the pH is both 7.2;

[0063] (2) Mix the potassium embedding active material (copper ferrocyanide), conductive carbon black, and aqueous electrolyte in a mass ratio of 85:10:5, then add it to 1 mol / L concentrated brine and mix it to obtain a potassium-poor electrode liquid with a solid content of 20%; Mix the potassium-depleting active material (copper ferrocyanide), conductive carbon black, and aqueous electrolyte in a mass ratio of 85:10:5, then add it to 1 mol / L concentrated brine and mix it to obtain a potassium-rich electrode liquid with a solid content of 20%; Inject the potassium-poor electrode liquid into the second electrode liquid storage tank 2-2 of the first system, inject the potassium-rich electrode liquid into the first electrode liquid storage tank 1-1 of the first system, and start the first electrode liquid circulation pump 2-1 of the first system and the second electrode liquid circulation pump 1-2 of the first system;

[0064] (3) Connecting the positive electrode 4 and the negative electrode 3 of the first system to a power source, applying a voltage of 1.0 V, starting potassium extraction, and gradually reducing the current. After no significant change for 5 minutes, turn off the power source;

[0065] (4) The seawater extracted in the raw material zone 9 of the first system is introduced into the raw material zone 9 of the second system, and steps (1) to (3) are repeated. The voltage is increased to 1.5 V, potassium extraction begins, and the current gradually decreases. After 5 minutes without significant change, the power is turned off. The potassium ion extraction rate is calculated to be 70.2%.

[0066] Example 4

[0067] A method for extracting potassium using the continuous potassium extraction system in seawater in Example 1:

[0068] (1) Seawater is introduced into the raw material zone 9 at a rate of 5 mL / min, and a 0.5 M KCl solution is introduced into the extraction zone 10 at the same time. The temperature of the solutions in the raw material zone 9 and the extraction zone 10 are both 25°C, and the pH is both 7.2;

[0069] (2) Mix the potassium embedding active material (copper ferrocyanide), conductive carbon black and aqueous electrolyte in a mass ratio of 80:10:10, then add it to 0.5 mol / L concentrated brine and mix it to obtain a potassium-poor electrode liquid with a solid content of 20%; Mix the potassium-depleting active material (copper ferrocyanide), conductive carbon black and aqueous electrolyte in a mass ratio of 80:10:10, then add it to 0.5 mol / L concentrated brine and mix it to obtain a potassium-rich electrode liquid with a solid content of 20%; Inject the potassium-poor electrode liquid into the second electrode liquid storage tank 2-2, inject the potassium-rich electrode liquid into the first electrode liquid storage tank 1-1, and start the first electrode liquid circulation pump 2-1 and the second electrode liquid circulation pump 1-2;

[0070] (3) The positive electrode 4 and the negative electrode 3 were connected to a power supply, and a voltage of 1.0 V was applied to start the extraction of potassium. The current gradually decreased. After 5 minutes without significant change, the power supply was turned off to end the extraction. The potassium ion extraction rate was calculated to be 54.2%.

[0071] Example 5

[0072] A method for extracting potassium using the continuous potassium extraction system in seawater in Example 1:

[0073] (1) The desalinated brine is introduced into the raw material zone 9 at a rate of 5 mL / min, and a 0.5 M KCl solution is introduced into the extraction zone 10 at the same time. The temperature of the solutions in the raw material zone 9 and the extraction zone 10 are both 25° C. and the pH is 6.8;

[0074] (2) Mix the potassium embedding active material (copper ferrocyanide), conductive carbon black and aqueous electrolyte in a mass ratio of 85:10:5, then add them to 1 mol / L concentrated brine and mix them to obtain a potassium-poor electrode liquid with a solid content of 20%; Mix the potassium-depleting active material (copper ferrocyanide), conductive carbon black and aqueous electrolyte in a mass ratio of 85:10:5, then add them to 1 mol / L concentrated brine and mix them to obtain a potassium-rich electrode liquid with a solid content of 20%; Inject the potassium-poor electrode liquid into the second electrode liquid storage tank 2-2, inject the potassium-rich electrode liquid into the first electrode liquid storage tank 1-1, and start the first electrode liquid circulation pump 2-1 and the second electrode liquid circulation pump 1-2;

[0075] (3) The positive electrode 4 and the negative electrode 3 were connected to a power supply, and a voltage of 1.0 V was applied to start the extraction of potassium. The current gradually decreased. After 5 minutes without significant change, the power supply was turned off to end the extraction. The potassium ion extraction rate was calculated to be 57.8%.

[0076] Example 6

[0077] A method for extracting potassium using the continuous potassium extraction system in seawater in Example 1:

[0078] (1) Seawater is introduced into the raw material zone 9 at a rate of 5 mL / min, and a 0.5 M KCl solution is introduced into the extraction zone 10 at the same time. The temperature of the solutions in the raw material zone 9 and the extraction zone 10 are both 25°C, and the pH is both 7.0;

[0079] (2) Mix the potassium embedding active material (copper nickel ferrocyanide), conductive carbon black and aqueous electrolyte in a mass ratio of 85:10:5, then add it to 1 mol / L concentrated brine and mix it to obtain a potassium-poor electrode liquid with a solid content of 20%; Mix the potassium-depleting active material (copper nickel ferrocyanide), conductive carbon black and aqueous electrolyte in a mass ratio of 85:10:5, then add it to 1 mol / L concentrated brine and mix it to obtain a potassium-rich electrode liquid with a solid content of 20%; Inject the potassium-poor electrode liquid into the second electrode liquid storage tank 2-2, inject the potassium-rich electrode liquid into the first electrode liquid storage tank 1-1, and start the first electrode liquid circulation pump 2-1 and the second electrode liquid circulation pump 1-2;

[0080] (3) The positive electrode 4 and the negative electrode 3 were connected to a power supply, and a voltage of 1.0 V was applied to start the extraction of potassium. The current gradually decreased. After 5 minutes without significant change, the power supply was turned off to end the extraction. The potassium ion extraction rate was calculated to be 57.5%.

[0081] Example 7

[0082] A method for extracting potassium using the continuous potassium extraction system in seawater in Example 1:

[0083] (1) Seawater is introduced into the raw material zone 9 at a rate of 5 mL / min, and a 0.5 M KCl solution is introduced into the extraction zone 10 at the same time. The temperature of the solutions in the raw material zone 9 and the extraction zone 10 are both 25°C, and the pH is both 7.0;

[0084] (2) Mix the potassium embedding active material (copper nickel ferrocyanide), conductive carbon black and aqueous electrolyte in a mass ratio of 85:10:5, then add it to 1 mol / L concentrated brine and mix it to obtain a potassium-poor electrode liquid with a solid content of 20%; Mix the potassium-depleting active material (copper nickel ferrocyanide), conductive carbon black and aqueous electrolyte in a mass ratio of 85:10:5, then add it to 1 mol / L concentrated brine and mix it to obtain a potassium-rich electrode liquid with a solid content of 20%; Inject the potassium-poor electrode liquid into the second electrode liquid storage tank 2-2, inject the potassium-rich electrode liquid into the first electrode liquid storage tank 1-1, and start the first electrode liquid circulation pump 2-1 and the second electrode liquid circulation pump 1-2;

[0085] (3) The positive electrode 4 and the negative electrode 3 were connected to a power supply, and a voltage of 1.2 V was applied to start the extraction of potassium. The current gradually decreased. After 5 minutes without significant change, the power supply was turned off to end the extraction. The potassium ion extraction rate was calculated to be 59.2%.

[0086] Example 8

[0087] The difference from Example 2 is that in step (1), the temperature of the solution in the raw material zone 9 and the extraction zone 10 is 25° C., the pH is 8.5, and the final potassium ion extraction rate is 59.0%.

[0088] Example 9

[0089] The difference from Example 2 is that in step (1), the temperature of the solution in the raw material zone 9 and the extraction zone 10 is 25° C., the pH is 5.3, and the final potassium ion extraction rate is 57.7%.

[0090] Example 10

[0091] The difference from Example 2 is that in step (1), the temperature of the solution in the raw material zone 9 and the extraction zone 10 is 15° C., the pH is 7.2, and the final potassium ion extraction rate is 58.2%.

[0092] Embodiment 11

[0093] The difference from Example 2 is that in step (1), the temperature of the solution in the raw material zone 9 and the extraction zone 10 is 45° C., the pH is 7.2, and the final potassium ion extraction rate is 59.1%.

[0094] Comparative Example 1

[0095] The difference from Example 2 is that in step (2), the potassium embedding active substance (copper ferrocyanide), conductive carbon black and aqueous electrolyte are mixed in a mass ratio of 75:10:15; the potassium desorption active substance (copper ferrocyanide), conductive carbon black and aqueous electrolyte are mixed in a mass ratio of 75:10:15, and the final potassium ion extraction rate is 50.3%.

[0096] Comparative Example 2

[0097] The difference from Example 2 is that in step (2), the potassium embedding active substance (copper ferrocyanide), conductive carbon black and aqueous electrolyte are mixed in a mass ratio of 95:5:5; the potassium desorption active substance (copper ferrocyanide), conductive carbon black and aqueous electrolyte are mixed in a mass ratio of 95:5:5, and the final potassium ion extraction rate is 51.2%.

[0098] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A system for continuous extraction of potassium from seawater, characterized in that: The continuous potassium extraction system in seawater is composed of a positive electrode, a negative electrode, a first cation exchange membrane, a second cation exchange membrane, an anion exchange membrane, a potassium-rich area, a raw material area, an extraction area, a potassium-poor area and an electrode liquid circulation device; The first cation exchange membrane, the anion exchange membrane and the second cation exchange membrane are arranged vertically in parallel and spaced in sequence between the positive electrode and the negative electrode, and the negative electrode and the positive electrode are separated into a potassium-rich area, a raw material area, an extraction area and a potassium-poor area in sequence; the potassium-rich area and the potassium-poor area are connected by an electrode liquid circulation device to form a loop.

2. The system for continuous extraction of potassium from seawater according to claim 1, characterized in that: The cation exchange membrane is an ion exchange membrane selective for monovalent cations, and the number of the cation exchange membranes is ≥2; the anion exchange membrane is an ion exchange membrane selective for monovalent anions, and the number of the anion exchange membranes is ≥1.

3. The system for continuous extraction of potassium from seawater according to claim 1, characterized in that: The electrode liquid circulation device includes a first electrode liquid storage tank, a first electrode liquid circulation pump, a second electrode liquid storage tank and a second electrode liquid circulation pump; the top of the first electrode liquid storage tank is connected to the potassium-rich area, and the bottom is connected to the inlet of the first electrode liquid circulation pump; the outlet of the first electrode liquid circulation pump is connected to the potassium-poor area; the top of the second electrode liquid storage tank is connected to the potassium-poor area, and the bottom is connected to the inlet of the second electrode liquid circulation pump; the outlet of the second electrode liquid circulation pump is connected to the potassium-rich area.

4. The system for continuous extraction of potassium from seawater according to claim 1 or 3, characterized in that: The electrode liquid in the electrode liquid circulation device comprises potassium intercalation and deintercalation active substances, conductive carbon black and aqueous electrolyte; the solvent of the electrode liquid in the electrode liquid circulation device is concentrated brine.

5. The system for continuous extraction of potassium from seawater according to claim 4, characterized in that: The mass ratio of the potassium intercalation and deintercalation active material, the conductive carbon black and the aqueous electrolyte is (80-90): (5-10): (5-10); the solid content of the electrode liquid is 5-45%.

6. The system for continuous extraction of potassium from seawater according to claim 4, characterized in that: The potassium embedding and de-embedding active substance is a Prussian blue compound A x M[R(CN)6] 1-y □ y ·nH2O, wherein A is one or more of alkali metals or alkaline earth metals, M is a high-spin transition metal, R is a low-spin transition metal, □ is a [R(CN)6] defect, 0≤x≤2, 0≤y≤1.

7. The system for continuous extraction of potassium from seawater according to claim 1, characterized in that: The temperature of the solution in the raw material zone and the extraction zone is 5-80°C, and the pH is 2-9.

8. The system for continuous extraction of potassium from seawater according to claim 1, characterized in that: The voltage between the positive electrode and the negative electrode is 0.5-2.0V or the current density is ≤100mA / cm 2 .

9. A method for extracting potassium using the continuous potassium extraction system from seawater according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) introducing seawater or concentrated brine after desalination of seawater into the raw material area, and introducing extract into the extraction area; (2) injecting electrode liquid into the first electrode liquid storage tank and the second electrode liquid storage tank respectively, and starting the first electrode liquid circulation pump and the second electrode liquid circulation pump; (3) Connecting the positive electrode and the negative electrode to a power source, applying voltage, and starting potassium extraction; (4) Repeat steps (1) to (3) to complete the continuous extraction of potassium.

10. The method for extracting potassium using a continuous potassium extraction system from seawater according to claim 9, characterized in that: In step (1), the extract is a solution containing cations.

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