A gas-liquid-liquid three-phase reverse extraction pulse tower for extracting valuable metals

Abstract

The invention relates to a gas-liquid-liquid three-way back-extraction pulse tower for extracting valuable metals, including a tower body, a bottom expansion section, a top expansion section, pulse legs, a gas recovery device, and a gas mixing device. By specifically setting the connection relationship, arrangement method, and cooperation relationship of each device, the overall back-extraction pulse tower can greatly improve the back-extraction efficiency and increase the gas utilization rate during operation.

Description

Technical Field

[0001] This invention belongs to the field of extraction technology in chemical separation, specifically relating to extraction towers, extraction methods and applications, and more specifically to a gas-liquid-liquid three-phase reverse extraction pulse tower for extracting valuable metals. Background Technology

[0002] Solvent extraction is a process that utilizes the different partition ratios of substances in organic and aqueous solutions to achieve separation or enrichment. In hydrometallurgy, it is commonly used to extract valuable metals from leachates, solutions, or brine lake solutions. The process mainly includes three steps: extraction, washing, and back-extraction. In the back-extraction process, the organic solution already loaded with valuable metals is controlled through acid-base balance to allow the metal ions to redissolve in the aqueous phase for the preparation of metal salt products. This also ensures that the organic solvent no longer contains metal ions and can be reused in the extraction stage, achieving the recycling of the extractant. However, during back-extraction, to maximize the dissolution of metal ions from the organic solution into the aqueous phase, the pH of the aqueous phase needs to be controlled using acids and bases, depending on the properties of the extractant, resulting in the consumption and waste of acids and bases. In recent years, with the development of solvent extraction technology, the three-phase CO2 back-extraction method has been gradually applied to the back-extraction of metal ions in organic solutions, such as the CO2 three-phase back-extraction method for lithium extraction from salt lakes and the CO2 three-phase back-extraction method for solutions containing rubidium and cesium. By introducing CO2 to form H2CO3 during the back-extraction process and adjusting the pH of the aqueous phase, the back-extraction of metals such as lithium, rubidium, and cesium can be achieved. This process does not require the use of acid, and the resulting solution can be directly concentrated at high temperature to obtain the product, thus making the process green and economical.

[0003] However, the commonly used three-phase reverse extraction equipment in industry is the stirred tank, which suffers from problems such as low extraction efficiency, intermittent operation, low gas utilization, large equipment footprint, poor sealing, and high energy consumption. Extraction towers are an important separation device in hydrometallurgy. A single extraction tower has the advantage of multiple theoretical stages. Applying extraction towers to three-phase reverse extraction not only utilizes the advantages of multi-stage extraction to increase gas residence time and gas utilization, but the clarification sections at the top and bottom of the extraction tower can ensure continuous discharge after gas-liquid-liquid phase separation, achieving continuous operation.

[0004] Chinese patent publication CN110656239 A discloses a method for extraction-back-extraction separation and purification of lithium, which includes a pulse-type extraction tower with stirring. The stirring ensures full contact between the gas, liquid, and liquid phases, and the pulse provides power for the countercurrent of the liquid phase. However, existing devices that rely on stirring to achieve full contact between the three phases still suffer from problems such as low equipment throughput, weak decontamination capacity, high energy consumption, and difficulty in maintaining moving parts. In addition, the high linear velocity of the agitator blade tip easily causes oil droplets and bubbles to break into extremely small droplets and bubbles, resulting in difficulties in phase separation, gas-liquid entrainment, and oil-water entrainment. Summary of the Invention

[0005] The purpose of this invention is to provide a gas-liquid-liquid three-phase back-extraction tower that is simple in structure, stable in operation, has a large flooding load, high gas utilization rate, and saves energy. It employs a combination of baffles and sieves. The baffles increase the gas phase residence time, the pulses and sieves enhance the redistribution of gas and droplets, and the gas partial pressure is adjusted to enhance the three-phase mass transfer rate, thus achieving enhanced mass transfer.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A gas-liquid-liquid three-way reverse extraction pulse tower for extracting valuable metals includes a tower body, a bottom expansion section, a top expansion section, pulse legs, a gas recovery device, and a gas mixing device.

[0008] The bottom enlarged section is located below the tower body, and the top enlarged section is located above the tower body. The bottom enlarged section, the tower body, and the top enlarged section are interconnected, and the diameters of the bottom enlarged section and the top enlarged section are larger than the diameter of the tower body.

[0009] The tower body is provided with a working chamber, in which tower body components are evenly distributed longitudinally. The tower body components include an outer ring plate, an inner ring plate, and a sieve plate. The outer ring plate is funnel-shaped with a higher outer edge and a lower inner ring. The outer diameter of the outer ring plate is the same as the inner diameter of the tower body, and the outer ring plate is connected to the inner wall of the tower body through its outer edge. The inner diameter of the funnel-shaped outer ring plate is 30-75% of the inner diameter of the tower body. The inner ring plate is a horizontal plate structure, and there is a gap between the outer edge of the inner ring plate and the inner wall of the tower body. The outer diameter of the inner ring plate is 60-90% of the inner diameter of the tower body. One or more outer ring plates and one or more inner ring plates are arranged alternately from top to bottom to form a plate ring group. One or more sieve plates are arranged below every 3-20 plate ring groups. The sieve plate is provided with a densely distributed through-hole structure. The diameter of each through-hole structure is 3-6 mm, and the opening rate of the sieve plate is 20-40%.

[0010] The appropriate aperture, porosity, and number of spacer rings can be selected based on the gas flow rate.

[0011] The pulse leg is mounted on the bottom enlarged section, the gas recovery device is connected to the top enlarged section via a pipe, and the gas mixing device is connected to both the gas recovery device and the bottom enlarged section via pipes.

[0012] Preferably, a light phase outlet and a heavy phase inlet are provided on the side of the top enlarged section, with the light phase outlet located above the heavy phase inlet. An exhaust port is provided at the top of the top enlarged section. Demisting packing is horizontally placed inside the top enlarged section between the exhaust port and the light phase outlet, and coalescing packing is horizontally placed inside the top enlarged section between the light phase outlet and the heavy phase inlet. The gas recovery device is provided with a recovery gas inlet and a processed gas outlet. The gas mixing device is provided with a first gas inlet, a second gas inlet, and an exhaust port. The exhaust port is connected to the recovery gas inlet of the gas recovery device through a pipe, and the processed gas outlet of the gas recovery device is connected to the first gas inlet of the gas mixing device through a pipe.

[0013] The demisting packing is installed between the light phase outlet pipe and the gas phase outlet pipe to prevent organic matter entrained by the gas from entering the exhaust port. The coalescing packing is installed between the heavy phase inlet and the light phase outlet to enhance the coalescence of small droplets and the separation of oil and water, preventing small droplets from following the light phase into the light phase outlet pipe.

[0014] Preferably, the gas-liquid-liquid three-way reverse extraction pulse tower further includes a gas storage tank, which is connected to the second gas inlet of the gas mixing device through a pipeline.

[0015] Preferably, a light phase inlet, a gas phase inlet, a heavy phase outlet, and a pulse leg inlet are provided on the side of the bottom enlargement section. The heavy phase outlet is located at the bottommost end, and the light phase inlet is located at the topmost end. The gas phase inlet is connected to the exhaust port of the gas mixing device through a pipe. A light phase distributor is provided at the light phase inlet inside the bottom enlargement section, and a gas phase distributor is provided at the gas phase inlet inside the bottom enlargement section to ensure the initial droplet distribution of the light and gas phases. The pulse leg inlet is connected to the bottom end of the pulse leg, and the top end of the pulse leg is connected to the compressed air pipe. An exhaust valve is provided at one end of the top end of the compressed air pipe, and an intake valve is provided at the other end.

[0016] Preferably, the gas recovery device relies on a dryer, a one-way valve, a regulating valve, and a compressor to achieve gas recovery.

[0017] Preferably, the gas mixing device is a pressure variation mixer, which achieves gas mixing by adjusting the pressure variation.

[0018] Preferably, the light phase distributor includes a bottom light phase pipe and a top light phase injection disc. The light phase pipe is connected to the light phase inlet, and the light phase injection disc has a disc-shaped structure with numerous openings on the top, through which the light phase is injected upward.

[0019] Preferably, the gas phase distributor includes a bottom gas phase pipe and a top gas phase injection disc. The gas phase pipe is connected to the gas phase inlet, and the gas phase injection disc has a disc-shaped structure with numerous openings on the top, through which the gas phase is injected upwards.

[0020] Gas recovery devices can be used to recycle and reuse gases that are costly or difficult to process.

[0021] Preferably, the funnel shape of the outer ring plate is circular, elliptical, rectangular or polygonal.

[0022] Preferably, the inner ring plate has a plate-like structure, such as a flat plate, an arc-shaped plate, or a corrugated plate.

[0023] Preferably, the outer ring plate, inner ring plate, and sieve plate are all erected and fixed by multiple vertically arranged support rods.

[0024] Preferably, the inner ring plate has a plate-like structure, such as a flat plate, an arc-shaped plate, or a corrugated plate. An outer ring plate and an inner ring plate are arranged alternately from top to bottom to form a plate ring group, and a sieve plate is placed below every 5 to 20 plate ring groups.

[0025] Preferably, the angle between the outer ring plate and the inner wall of the tower is 45° to 85°.

[0026] Preferably, the angle is set within the range of 45 to 85° according to the gas flow rate; the larger the flow rate, the smaller the angle.

[0027] Preferably, the gas mixing device is further provided with a third gas inlet, which is connected to an external non-reverse extraction gas source and is used to discharge the non-reverse extraction gas source into the gas mixing device through the third gas inlet, and the gas mixing device mixes the non-reverse extraction gas source with the reverse extraction gas source.

[0028] A back-extraction method for extracting valuable metals, the back-extraction method using the aforementioned gas-liquid-liquid three-stage back-extraction pulse tower for extracting valuable metals, comprising the following steps:

[0029] (1) The heavy phase material is discharged into the top expansion section through the heavy phase inlet and fills the tower body and bottom expansion section. After the tower body is partially filled with heavy phase material, the inlet valve and the exhaust valve are opened and closed in a cycle. When the inlet valve is opened, the exhaust valve is closed and the compressed gas enters the pulse leg. The liquid level in the pulse leg drops, causing the liquid level inside the tower body to rise. When the inlet valve is closed, the exhaust valve is opened and the gas in the pulse leg is discharged upward. The liquid level rises, causing the liquid level inside the tower body to drop. The inlet valve and the exhaust valve are opened and closed in sequence according to this cycle, so that pulses are generated inside the tower.

[0030] (2) After the pulse is generated in step (1), light phase material is discharged into the bottom expansion section through the light phase inlet, and mixed gas is discharged into the bottom expansion section through the gas phase inlet. The light phase material and mixed gas move upward through the tower body, and then the interface between the heavy phase and the light phase is formed in the top expansion section. The resulting back-extraction phase is discharged through the heavy phase outlet, the resulting organic phase is discharged through the light phase liquid outlet, and the reaction gas is discharged through the exhaust port. The discharged gas is discharged into the gas recovery device for treatment and then discharged into the gas mixing device. The gas storage tank is filled with back-extraction gas source, and back-extraction gas is charged into the gas mixing device from the gas storage tank. At the same time, a non-reverse-extraction gas source is introduced into the gas mixing device. After the reverse-extraction gas source and the non-reverse-extraction gas source are mixed in the gas mixing device, the mixed gas is discharged into the gas phase inlet through the exhaust port of the gas mixing device. The fluid flowing upward in the tower first flows through the gap between the inner ring plate and the inner wall of the tower, and then flows upward through the central opening of the inner ring of the outer ring plate. The fluid flows in an "S" shape. After the upward-flowing fluid flows through the gap between the inner ring plate and the inner wall of the tower, it first flows to the angle between the lower edge of the outer ring plate and the inner wall of the tower. The bubbles move preferentially to this angle and stay and accumulate on the wall surface at this point.

[0031] Because the density of bubbles is much lower than that of the aqueous and organic phases, bubbles preferentially move to the angle between the outer ring plate and the tower wall, and accumulate on the wall, effectively increasing the residence time of bubbles and improving the gas absorption rate.

[0032] (3) Continue to perform step (2) for back-extraction. After the material back-extraction is completed, close the gas phase inlet, light phase inlet, heavy phase liquid inlet, exhaust valve and air inlet valve. After the material in the tower is discharged, close the heavy phase outlet and light phase liquid outlet. The back-extraction ends.

[0033] Preferably, the back-extraction gas source is carbon dioxide, and the non-back-extraction gas source is one or more of helium, neon, argon, krypton, xenon, radon, nitrogen, or air.

[0034] In the mixed gas formed by the non-reverse extraction gas source and the reverse extraction gas source, the volume proportion of the non-reverse extraction gas source is 30-70%.

[0035] The gas composition can be adjusted. With the amount of gas used for back-extraction remaining unchanged, the inlet gas flow rate can be increased. The moderate increase in gas flow rate can enhance the turbulence and interfacial mixing of the liquid and liquid phases, improve the liquid-liquid mass transfer, and at the same time prevent the bubbles from becoming too small during the process of gas gradually transferring mass to the liquid phase. This would cause the force of gas diffusion outward to be lower than the surface tension of bubble contraction, thus limiting the diffusion of gas into the liquid phase.

[0036] Preferably, in step (2), the flow rate of the mixed gas discharged into the bottom expansion section through the gas phase inlet is (7.8 × 10⁻⁶). -4 ~7.8×10 -3) m / s.

[0037] Preferably, in step (1), the pulse intensity is controlled by the pressure of the compressed air intake and the opening and closing time of the intake valve and the exhaust valve.

[0038] Preferably, the pulse in step (1) has an amplitude of 8~15mm and a frequency of 0.15~0.8Hz.

[0039] The technical advantages of this invention are as follows:

[0040] This invention, through the specific structural design of the internal components of the tower, and the coordination (positional, proportional, and quantitative relationships) of the outer ring plate, inner ring plate, and sieve plate, ensures thorough breaking down and uniform dispersion of the organic phase and bubbles. This increases the residence time of the dispersed phase droplets and bubbles, allowing for more sufficient dispersion and reaction time. Combined with specific pulse and gas distribution methods, this results in high back-extraction efficiency and high gas utilization. It eliminates the need for a stirring device, thus requiring a small footprint, producing minimal noise and minimal environmental impact, while also saving energy. Furthermore, the specific structure and pulse method ensure good operational continuity; the thorough back-extraction requires less extractant; and the absence of powered components facilitates easy maintenance and reduces equipment operating costs.

[0041] By setting specific internal component structures and relying on the cooperation of the sieve plate and pulse, the bubbles and droplets are fully dispersed, resulting in more uniform dispersion and greatly reducing the entrainment of oil, water, gas, and liquid. Through the specific arrangement of the sieve plate, inner ring plate, and outer ring plate, the residence time of the bubbles is greatly increased through the baffle. By setting specific gas recovery and mixing related devices, the gas mass transfer rate is greatly improved, and the gas utilization rate is greatly increased. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of a gas-liquid-liquid three-phase pulse back-extraction tower according to the present invention.

[0043] Figure 2 yes Figure 1 A partial structural diagram of the internal components of the central tower.

[0044] Figure 3 These are schematic diagrams of the outer ring plate and the inner ring plate from the front and top views.

[0045] in Figure 3 (a) is a schematic diagram of the outer ring plate from the front and top views. Figure 3 (b) is a structural schematic diagram of the inner ring plate from the front and top views.

[0046] Wherein: 1: Top enlargement section; 2: Tower body; 3: Bottom enlargement section; 4: Exhaust port; 5: Light phase liquid outlet; 6: Demisting packing; 7: Coalescing packing; 8: Outer ring plate; 9: Inner ring plate; 10: Sieve plate; 11: Light phase inlet; 12: Gas phase inlet; 13: Pulse leg; 14: Heavy phase outlet; 15: Pulse leg inlet; 16: Gas recovery device; 17: Gas mixing device; 18: Gas storage tank; 19: Exhaust valve; 20: Inlet valve; 21: Compressed gas pipe; 22: Light phase distributor; 23: Gas phase distributor; 24: Support rod; 25: Heavy phase liquid inlet. Detailed Implementation

[0047] The process technology solution of the present invention will be further described below with reference to the embodiments and accompanying drawings. The orientations mentioned in this specification are based on the orientation of the gas-liquid-liquid three-phase reverse extraction tower of the present invention during normal operation, and do not limit the orientation during storage and transportation. They only represent relative positional relationships and do not represent absolute positional relationships.

[0048] like Figure 1 As shown, the main body of the gas-liquid-liquid three-phase reverse extraction tower is a vertically placed tower body 2. The top of the tower body 2 is connected to the top expansion section 1, and the bottom of the tower body 2 is connected to the bottom expansion section 3. The top expansion section 1 is provided with a heavy phase inlet 25, a light phase outlet 5, and an exhaust port 4. The top expansion section is provided with demister packing 6 and coalescing packing 7. The bottom expansion section 3 is provided with a light phase inlet 11, a pulse leg inlet 15, a gas phase inlet 12, and a heavy phase outlet 14. The bottom expansion section is provided with a light phase distributor 22 and a gas phase distributor 23, which are respectively connected to the light phase inlet 11 and the gas phase inlet 12. The pulse leg inlet 15 is connected to the pulse leg 13. The top of the pulse leg 13 is connected to a compressed air pipe 21. An exhaust valve 19 and an inlet valve 20 are connected to the compressed air pipe. The inlet valve 20 is connected to a compressed air source, and the exhaust valve is connected to a tail gas absorption device or the atmosphere. The opening and closing of the exhaust valve 19 and the inlet valve 20 control the discharge and entry of gas in the pulse leg, generating pulses in the tower.

[0049] The exhaust port 4 is connected to an external gas recovery device 16. Gases with high cost or difficult post-processing can be recycled and reused through the gas recovery device. The gas phase inlet 12 is connected to an external gas mixing device 17, which can mix the gas source for back-extraction with other non-back-extraction gas sources. The non-back-extraction gas sources account for 30-70% of the total gas volume.

[0050] The interior of tower body 2 is installed as follows Figure 2 The combined internal components shown include, as follows: Figure 3 (a) shows the outer ring plate 8. Figure 3(b) As shown, the inner ring plate 9 and sieve plate 10 are longitudinally arranged in the working chamber via support rods 24. The outer ring plate 8 has the same outer diameter as the inner diameter of the tower body and is tightly attached to the tower wall. The tower plate has an opening inside, with a diameter of 1 / 3 to 3 / 4 of the inner diameter of the tower body. The outer diameter of the inner ring plate 9 is 9 / 10 to 3 / 5 of the inner diameter of the tower body and has a gap with the tower wall. The inner ring plate and the outer ring plate are arranged in a specific order. Figure 2 The plates are arranged alternately, with an inner ring plate and an outer ring plate as a group. A sieve plate 10 is inserted in every 5 to 20 groups of plate rings. The sieve plate has a hole diameter range of 3 to 6 mm and an opening rate of 20% to 40%. The appropriate hole diameter, opening rate and number of spacer plate ring groups can be selected according to the gas flow rate.

[0051] When the stripping column is operating and using an aqueous phase continuously, the column is first filled with material through the heavy phase inlet 25. After the column is partially filled with material, the inlet valve 20 and the outlet valve 19 are opened. When the inlet valve 20 is open and the outlet valve 19 is closed, compressed air enters the pulse leg, causing the liquid level in the pulse leg to drop, which in turn causes the liquid level inside the column to rise. When the inlet valve 20 is closed and the outlet valve 19 is open, the gas in the pulse leg is discharged, causing the liquid level to rise, which in turn causes the liquid level inside the column to drop. The inlet valve 20 and the outlet valve 19 are opened and closed in this manner in sequence, generating pulses inside the column. The pulse intensity is controlled by the air intake pressure and the valve opening and closing time. The extractant is introduced into the column through the light phase inlet 11 at a flow rate ratio (i.e., volume ratio) of 0.5-8 between the organic phase and the aqueous phase, with an apparent gas velocity of 7.8 × 10⁻⁶. -4 Up to 7.8×10 -3 Gas is introduced into the tower at a speed of m / s through the gas inlet 12. Once the oil-water interface is established in the top expansion section 1, the back-extraction aqueous phase begins to be discharged from the heavy phase outlet 14, while the organic phase begins to overflow from the light phase outlet 5. Gas is discharged from the exhaust port 4, marking the start of the complete back-extraction operation. Under the influence of gravity, the aqueous phase moves downwards, while the organic and gas phases move upwards, forming countercurrent back-extraction. Under the action of the sieve plate 10 and pulses, the organic phase and bubbles are fully broken down and dispersed. The outer ring plate 8 and inner ring plate 9 increase the residence time of the dispersed phase droplets and bubbles. The gas discharged from the exhaust port 4 is collected and recycled by the gas recovery device 16. The back-extraction gas source and the non-back-extraction gas source are respectively discharged into the gas mixing device 17 and then mixed at a ratio of 30-70% before entering the gas inlet 12 (both the back-extraction gas source and the non-back-extraction gas source are external gas sources), achieving a large inlet gas flow rate, which can enhance the turbulence of the liquid-liquid two-phase flow and the gas phase diffusion rate.

[0052] Adopting such Figures 1-3 The effects of the gas-liquid-liquid three-stage back-extraction tower shown in the specific embodiment of metallurgical back-extraction are as follows:

[0053] A gas-liquid-liquid three-stage back-extraction column for lithium extraction from salt lake brine employs a borosilicate glass back-extraction column with a diameter of DN50. The effective back-extraction section has a height of 2m. The organic phase consists of a kerosene solution containing tri-n-octylphosphine oxide (TOPO) and 1g / L Li. + The feed flow rate was 1 L / h, the aqueous phase was ultrapure water with a feed flow rate of 1.5 L / h, the gas phase inlet was a mixture of 60% CO2 and 40% N2 with an inlet flow rate of 8 L / h, the pulse amplitude was 5 mm, and the frequency was 0.5 Hz. Water was used as the continuous phase (heavy phase), and the TOPO-containing loaded organic matter was used as the dispersed phase (light phase). The pure aqueous solution entered through the heavy phase inlet and exited through the heavy phase outlet, while the organic phase entered through the light phase inlet and exited through the light phase outlet. The mixed gas entered through the gas inlet and exited through the exhaust port. After 24 hours of stable operation, the Li content in the organic phase was measured. + <20mg / L, back-extraction rate> 98%, CO2 utilization rate>65%, the back-extraction rate meets the industrial index requirements, and the CO2 utilization rate is far higher than the engineering index. This embodiment fully achieves the gas-liquid-liquid three-way back-extraction effect described in this invention.

[0054] Comparative Example 1:

[0055] This comparative example uses an existing stirred tank reactor for lithium extraction from salt lake brine, with the same processing volume as in Example 1. In a 5L stirred tank reactor, the aqueous phase is 1.5L, the organic phase is 1L, and the gas flow rate is 8L / h. After stirring for 1 hour, the Li content in the organic phase is measured. + The concentration was 300 mg / L, the back-extraction rate was 70%, and the CO2 utilization rate was 46%. However, the energy consumption of the stirring motor was 200W, while the energy consumption of Example 1 was 20L of compressed air, requiring a 320W air compressor with a power consumption of 30W per hour. Thus, under the same conditions, the present invention reduces energy consumption by more than 80% compared to the existing stirred tank, and increases the back-extraction rate by 28% and the CO2 utilization rate by 19%.

[0056] Example 2:

[0057] A gas-liquid-liquid three-stage back-extraction column for cesium extraction is described, employing a stainless steel back-extraction column with a diameter of DN150 and an effective back-extraction section height of 10m. In this embodiment, the angle between the outer ring plate and the inner wall of the column is 45°. The organic phase is a kerosene solution containing 4-sec-butyl-2-(α-methylbenzyl)phenol (t-BAMBP) and 1.2 g / L of Cs. +The feed flow rate was 180 L / h, the aqueous phase was ultrapure water with a feed flow rate of 41 L / h, and the gas phase inlet was a mixture of 30% CO2 and 70% N2 with an inlet flow rate of 180 L / h. The pulse amplitude was 10 mm and the frequency was 0.3 Hz. Water was used as the continuous phase, and the organic load containing t-BAMBP was used as the dispersed phase. The pure aqueous solution entered through the heavy phase inlet and exited through the heavy phase outlet. The organic phase entered through the light phase inlet and exited through the light phase outlet. The mixed gas entered through the gas inlet and exited through the exhaust port. After 24 hours of stable operation, the Cs in the organic phase was measured. + <20mg / L, back-extraction rate> 98%, CO2 utilization rate 65%, the back-extraction rate meets the industrial index requirements, and the CO2 utilization rate is far higher than the engineering index. This embodiment fully achieves the gas-liquid-liquid three-way back-extraction effect described in this invention.

[0058] Comparative Example 2:

[0059] In this comparative example, the angle between the outer ring plate and the inner wall of the tower is 90°, and other settings are completely consistent with those in Example 2. After 24 hours of stable operation, the Cs concentration in the organic phase was measured. + The concentration was 180 mg / L, the back-extraction rate was 85%, and the CO2 utilization rate was 56%. Compared with Example 2, because the angle between the outer ring plate and the inner wall of the tower was set to a right angle (not within the angle range set by this invention), the back-extraction rate decreased by 13% and the CO2 utilization rate decreased by 9%. This shows that the setting of the outer ring plate in this invention is an inventive setting. This setting and the angle setting allow the foam to achieve the optimal residence time, which does not affect the fluidity and allows the CO2 to have a longer residence time to contact and react with the aqueous phase, thus resulting in a good final back-extraction effect.

[0060] Example 3:

[0061] A gas-liquid-liquid three-stage back-extraction column for rubidium extraction is described. The column is a stainless steel back-extraction column with a diameter of DN150. The effective back-extraction section has a height of 10m. The organic phase is a kerosene solution containing 4-sec-butyl-2-(α-methylbenzyl)phenol (t-BAMBP) and 0.8 g / L of Rb. + The feed flow rate was 180 L / h, the aqueous phase was ultrapure water with a feed flow rate of 41 L / h, and the gas phase inlet was a mixture of 30% CO2 and 70% N2 with an inlet flow rate of 180 L / h. The pulse amplitude was 10 mm and the frequency was 0.3 Hz. Water was used as the continuous phase, and the organic load containing t-BAMBP was used as the dispersed phase. The pure aqueous solution entered through the heavy phase inlet and exited through the heavy phase outlet. The organic phase entered through the light phase inlet and exited through the light phase outlet. The mixed gas entered through the gas inlet and exited through the exhaust port. After 24 hours of stable operation, the Rb content in the organic phase was measured. +<5mg / L, back-extraction rate> 99%, CO2 utilization rate>70%, the back-extraction rate meets the industrial index requirements, and the CO2 utilization rate is far higher than the engineering index. This embodiment fully achieves the gas-liquid-liquid three-way back-extraction effect described in this invention.

[0062] Comparative Example 3:

[0063] This comparative example did not use a sieve plate; all other settings were identical to those in Example 3. After 24 hours of stable operation, the Rb content in the organic phase was measured. + The concentration was 100 mg / L, the back-extraction rate was 87%, and the CO2 utilization rate was 62%, which shows that the specific arrangement of the components in the tower body of the present invention is closely coordinated. If one of them is missing, it is not only the independent function of that component that is lost, but the overall effect is lost, thus proving that the specific arrangement of the components in the tower body of the present invention is closely coordinated.

[0064] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A gas-liquid-liquid three-stage reverse extraction pulse tower for extracting valuable metals, characterized in that, It includes the tower body, bottom expansion section, top expansion section, pulse legs, gas recovery device, and gas mixing device; The bottom enlarged section is located below the tower body, and the top enlarged section is located above the tower body. The bottom enlarged section, the tower body, and the top enlarged section are interconnected, and the diameters of the bottom enlarged section and the top enlarged section are larger than the diameter of the tower body. The tower body has a working chamber, within which tower body components are arranged longitudinally and evenly. These components include an outer ring plate, an inner ring plate, and a sieve plate. The outer ring plate is funnel-shaped with a higher outer edge and a lower inner ring. Its outer diameter is the same as the tower body's inner diameter, and it connects to the inner wall of the tower body via its outer edge. The inner diameter of the funnel-shaped outer ring plate is 30-75% of the tower body's inner diameter. The inner ring plate is a horizontally placed plate structure, with a gap between its outer edge and the inner wall of the tower body. Its outer diameter is 60-90% of the tower body's inner diameter, and it is larger than the inner diameter of the funnel-shaped outer ring plate. One or more outer ring plates and one or more inner ring plates are arranged alternately from top to bottom to form plate ring groups. One or more sieve plates are placed below every 3-20 plate ring groups. The sieve plates have a densely distributed perforated structure, with each perforation having a diameter of 3-6 mm. mm, the sieve plate opening ratio is 20~40%; the angle between the outer ring plate and the inner wall of the tower is 45~85°; The fluid flowing upwards inside the tower first flows through the gap between the inner ring plate and the inner wall of the tower, and then flows upwards through the central opening of the inner ring of the outer ring plate. The fluid flows in an "S" shape. After flowing upwards through the gap between the inner ring plate and the inner wall of the tower, the fluid first flows to the angle between the lower edge of the outer ring plate and the inner wall of the tower. Bubbles move preferentially to this angle and stay and accumulate on the wall at this point. The pulse leg is mounted on the bottom enlarged section, the gas recovery device is connected to the top enlarged section via a pipe, and the gas mixing device is connected to both the gas recovery device and the bottom enlarged section via pipes.

2. The gas-liquid-liquid three-phase reverse extraction pulse tower for extracting valuable metals according to claim 1, characterized in that, A light phase outlet and a heavy phase inlet are provided on the side of the top enlarged section, with the light phase outlet located above the heavy phase inlet. An exhaust port is provided at the top of the top enlarged section. Demisting packing is horizontally placed inside the top enlarged section between the exhaust port and the light phase outlet, and coalescing packing is horizontally placed inside the top enlarged section between the light phase outlet and the heavy phase inlet. The gas recovery device is provided with a recovery gas inlet and a processed gas outlet. The gas mixing device is provided with a first gas inlet, a second gas inlet, and an exhaust port. The exhaust port of the top enlarged section is connected to the recovery gas inlet of the gas recovery device through a pipe, and the processed gas outlet of the gas recovery device is connected to the first gas inlet of the gas mixing device through a pipe.

3. The gas-liquid-liquid three-phase reverse extraction pulse tower for extracting valuable metals according to claim 2, characterized in that, The gas-liquid-liquid three-way reverse extraction pulse tower also includes a gas storage tank, which is connected to the second gas inlet of the gas mixing device through a pipeline.

4. The gas-liquid-liquid three-stage reverse extraction pulse tower for extracting valuable metals according to claim 2 or 3, characterized in that, A light phase inlet, a gas phase inlet, a heavy phase outlet, and a pulse leg inlet are provided on the side of the bottom expansion section. The heavy phase outlet is located at the bottommost end, and the light phase inlet is located at the topmost end. The gas phase inlet is connected to the exhaust port of the gas mixing device through a pipeline. A light phase distributor is provided at the light phase inlet inside the bottom expansion section, and a gas phase distributor is provided at the gas phase inlet inside the bottom expansion section. The pulse leg inlet is connected to the bottom end of the pulse leg, and the top end of the pulse leg is connected to the compressed air pipe. An exhaust valve is provided at one end of the top end of the compressed air pipe, and an intake valve is provided at the other end.

5. The gas-liquid-liquid three-phase reverse extraction pulse tower for extracting valuable metals according to claim 4, characterized in that, The gas recovery device relies on a dryer, a one-way valve, a regulating valve, and a compressor to achieve gas recovery. The gas mixing device is a pressure-changing mixer, which achieves gas mixing by adjusting pressure changes. The light phase distributor includes a bottom light phase pipe and a top light phase injection disc. The light phase pipe is connected to the light phase inlet, and the light phase injection disc has a disc-shaped structure with numerous openings on the top, through which the light phase is injected upwards. The gas phase distributor includes a bottom gas phase pipe and a top gas phase injection disc. The gas phase pipe is connected to the gas phase inlet, and the gas phase injection disc has a disc-shaped structure with numerous openings on the top, through which the gas phase is injected upwards.

6. The gas-liquid-liquid three-phase reverse extraction pulse tower for extracting valuable metals according to any one of claims 1-3 or 5, characterized in that, The funnel shape of the outer ring plate is circular, elliptical, or polygonal. The inner ring plate has a plate-like structure, which can be a flat plate, an arc-shaped plate, or a corrugated plate. The outer ring plate, inner ring plate, and sieve plate are all erected and fixed by multiple vertically arranged support rods.

7. The gas-liquid-liquid three-phase reverse extraction pulse tower for extracting valuable metals according to any one of claims 1-3 or 5, characterized in that, An outer ring plate and an inner ring plate are arranged alternately from top to bottom to form a plate ring group, and a sieve plate is placed below every 5 to 20 plate ring groups.

8. The gas-liquid-liquid three-phase reverse extraction pulse tower for extracting valuable metals according to any one of claims 1-3 or 5, characterized in that, The angle is set within the range of 45 to 85° depending on the gas flow rate.

9. A method for back-extraction of valuable metals, characterized in that, The back-extraction method uses the gas-liquid-liquid three-stage back-extraction pulse tower for extracting valuable metals as described in any one of claims 1-8, and includes the following steps: (1) The heavy phase material is discharged into the top expansion section through the heavy phase inlet and fills the tower body and bottom expansion section. After the tower body is partially filled with heavy phase material, the inlet valve and the exhaust valve are opened and closed in a cycle. When the inlet valve is opened, the exhaust valve is closed and the compressed gas enters the pulse leg. The liquid level in the pulse leg drops, causing the liquid level inside the tower body to rise. When the inlet valve is closed, the exhaust valve is opened and the gas in the pulse leg is discharged upward. The liquid level rises, causing the liquid level inside the tower body to drop. The inlet valve and the exhaust valve are opened and closed in this cycle, so that pulses are generated inside the tower. (2) After the pulse is generated in step (1), light phase material is discharged into the bottom expansion section through the light phase inlet, and mixed gas is discharged into the bottom expansion section through the gas phase inlet. The light phase material and mixed gas move upward through the tower body, and then the interface between the heavy phase and the light phase is formed in the top expansion section. The resulting back-extraction phase is discharged through the heavy phase outlet, the resulting organic phase is discharged through the light phase liquid outlet, and the reaction gas is discharged through the exhaust port of the top expansion section. The discharged gas is discharged into the gas recovery device for treatment and then discharged into the gas mixing device. The gas storage tank is filled with back-extraction gas source, and the gas storage tank is filled into the gas mixing device. A back-extraction gas source is introduced, and a non-back-extraction gas source is introduced into the gas mixing device. The back-extraction gas source and the non-back-extraction gas source are mixed in the gas mixing device to form a mixed gas, which is discharged into the gas phase inlet through the exhaust port of the gas mixing device. The fluid flowing upward in the tower first flows through the gap between the inner ring plate and the inner wall of the tower, and then flows upward through the central opening of the inner ring of the outer ring plate. The fluid flows in an "S" shape. After the upward-flowing fluid flows through the gap between the inner ring plate and the inner wall of the tower, it first flows to the angle between the lower edge of the outer ring plate and the inner wall of the tower. The bubbles move to this angle first and stay and accumulate on the wall at this point. (3) Continue to perform step (2) for back-extraction. After the material back-extraction is completed, close the gas phase inlet, light phase inlet, heavy phase liquid inlet, exhaust valve and air inlet valve. After the material in the tower is discharged, close the heavy phase outlet and light phase liquid outlet. The back-extraction ends. The back-extraction gas source is carbon dioxide, and in the mixed gas formed by the non-back-extraction gas source and the back-extraction gas source, the volume ratio of the non-back-extraction gas source is 30-70%. In step (2), the flow rate of the mixed gas discharged into the bottom expansion section through the gas phase inlet is (7.8 × 10⁻⁶). -4 ~7.8×10 -3 ) m / s; In step (1), the pulse intensity is controlled by the pressure of the compressed air intake and the opening and closing time of the intake valve and exhaust valve.

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