A three-phase stripping device, a CO2 stripping co-production lithium carbonate device and method

Abstract

The application provides a three-phase stripping device, a CO2 stripping and lithium carbonate co-production device and a method. The three-phase stripping device comprises a Venturi jet device and a stripping tower. In the material conveying direction, the Venturi jet device comprises a converging section, a throat and a diffuser section in sequence. The outlet of the diffuser section is connected with the material inlet of the stripping tower. The front end of the converging section is provided with an organic liquid phase inlet and an aqueous phase inlet, and the organic liquid phase inlet and the aqueous phase inlet flow back to the converging section. Alternatively, the converging section comprises an organic liquid phase converging section and an aqueous phase converging section, and the organic liquid phase converging section and the aqueous phase converging section converge to the throat. The side wall of the throat or the front end of the throat is provided with a carbon dioxide suction inlet, and the carbon dioxide suction inlet is a plurality of holes uniformly distributed in the circumferential direction. The three-phase stripping device provided by the application can significantly improve the stripping efficiency, shorten the stripping time, improve the utilization rate of carbon dioxide, and improve the lithium recovery rate.

Description

Technical Field

[0001] This invention relates to the field of lithium extraction technology, and in particular to a three-stage back-extraction apparatus, an apparatus and method for CO2 back-extraction and co-production of lithium carbonate. Background Technology

[0002] Battery-grade lithium carbonate is a crucial raw material in lithium battery production, requiring high purity and strict control over impurity levels. Methods for purifying industrial-grade lithium carbonate to produce battery-grade lithium carbonate include: Li₂CO₃ recrystallization, causticization, electrolysis, carbonation precipitation, and carbonation decomposition. While Li₂CO₃ recrystallization is simple to operate and has low production costs, it has a long production cycle; the causticization method has a lengthy process, low product yield, and large residue volume.

[0003] Solvent extraction is a very popular new lithium extraction technology that utilizes the special extraction properties of organic solvents to achieve efficient lithium extraction.

[0004] CN112342407A discloses a method for back-extraction of lithium extract, which involves mixing the lithium extract with a back-extraction solution and back-extracting to obtain a back-extraction residue containing lithium bicarbonate. The pH of the back-extraction residue is 7-11, and its pH value is less than or equal to that of the lithium extract. The back-extraction residue is then heated to separate lithium carbonate. However, this method requires multiple back-extraction steps to achieve optimal back-extraction results, resulting in low back-extraction efficiency.

[0005] CN110656239A discloses a method for extraction-back-extraction separation and purification of lithium, comprising the following steps: using an extraction system containing a composite extractant, extracting and separating a lithium-containing solution under pH = 10-13 conditions to obtain a lithium-loaded organic phase; subjecting the lithium-loaded organic phase to gas-liquid-liquid three-stage back-extraction to obtain a lithium-loaded back-extraction solution; and subjecting the back-extraction solution to heat treatment and separation to obtain a lithium product and a separated mother liquor. However, the back-extraction efficiency still needs to be improved, and the back-extraction time is long.

[0006] Therefore, there is a need to develop devices and equipment that can improve back-extraction efficiency. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a three-stage back-extraction device, an apparatus and method for CO2 back-extraction and co-production of lithium carbonate. The Venturi jet injector completes the self-absorption and microbubble pre-dispersion of CO2 gas during the feeding stage, significantly increasing the initial phase boundary area and thus significantly improving the back-extraction efficiency.

[0008] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a three-stage back-extraction device, comprising a Venturi jet injector and a back-extraction tower. Along the material conveying direction, the Venturi jet injector sequentially comprises a contraction section, a throat, and a diffusion section. An organic liquid phase inlet and an aqueous phase inlet are provided at the front end of the contraction section, and the organic liquid phase inlet and the aqueous phase inlet return to the contraction section; alternatively, the contraction section comprises an organic liquid phase contraction section and an aqueous phase contraction section, and the organic liquid phase contraction section and the aqueous phase contraction section converge at the throat; a carbon dioxide intake port is provided on the side wall or at the front end of the throat, and the carbon dioxide intake port consists of a plurality of circumferentially uniformly distributed holes.

[0009] Preferably, the contraction section is a tapered cone shape along the material conveying direction.

[0010] Preferably, the inner diameter of the inlet of the contraction section is 25~80mm.

[0011] Preferably, the cone angle of the contraction section is 15~30°.

[0012] Preferably, the throat is a cylindrical section of equal diameter.

[0013] Preferably, the inner diameter of the throat is 0.33 to 0.5 times the inner diameter of the inlet.

[0014] Preferably, the ratio of the length of the throat to the inner diameter of the throat is (1~3):1.

[0015] Preferably, the diffusion section is a gradually expanding cone shape along the material conveying direction.

[0016] Preferably, the cone angle of the diffusion section is 7~15°.

[0017] Preferably, the ratio of the outlet inner diameter of the diffusion section to the inlet inner diameter of the contraction section is (1.2~1.5):1.

[0018] Preferably, the carbon dioxide inlet is connected to a carbon dioxide supply pipeline.

[0019] Preferably, the carbon dioxide inlet is connected to a carbon dioxide supply pipeline via a one-way valve.

[0020] Preferably, the carbon dioxide supply pipeline is equipped with a flow monitor.

[0021] Preferably, the material of the Venturi jet includes 316L stainless steel or corrosion-resistant alloy material.

[0022] Preferably, the back-extraction tower comprises a packed tower.

[0023] Preferably, the height-to-diameter ratio of the back-extraction tower is (3~10):1, and more preferably (4~8):1.

[0024] Preferably, the material of the back-extraction tower includes 316L stainless steel or corrosion-resistant alloy.

[0025] Preferably, the packed tower has a packing layer inside.

[0026] Preferably, the packing material in the packing layer includes structured packing and / or random packing.

[0027] Preferably, the structured packing includes wire mesh corrugated packing and / or perforated plate corrugated packing.

[0028] Preferably, the random packing includes any one or a combination of at least two of Pall rings, rectangular saddle rings, or stepped rings.

[0029] Preferably, the specific surface area of ​​the packing material in the packing layer is 200~800m². 2 / m 3 Preferably 350~500m 2 / m 3 Preferably, the back-extraction tower is equipped with a liquid distributor, which is located above the packing layer and at the outlet of the Venturi jet.

[0030] Preferably, the top of the back-extraction tower is provided with an oxide tower exhaust port.

[0031] Preferably, the stripping tower is further provided with a carbon dioxide inlet, and a gas distributor is provided at the bottom of the packing layer, which is connected to the carbon dioxide inlet.

[0032] Preferably, the bottom of the back-extraction tower is provided with a liquid collection section.

[0033] Preferably, the liquid collection section is provided with a mixture discharge port.

[0034] In a second aspect, the present invention provides a system apparatus for CO2 back-extraction and co-production of lithium carbonate, the system apparatus comprising the three-stage back-extraction apparatus described in the first aspect.

[0035] Preferably, the system includes an oil-water phase separator and a pyrolysis crystallization device. The oil-water phase separator is connected to the mixture outlet of the liquid collection section. An organic phase outlet is provided at the upper part of the oil-water phase separator, and a lithium bicarbonate solution outlet is provided at the lower part. The lithium bicarbonate solution outlet is connected to the pyrolysis crystallization device. The pyrolysis crystallization device includes a lithium carbonate slurry outlet and a pyrolysis carbon dioxide outlet.

[0036] Preferably, the pyrolysis crystallization apparatus includes a jacketed heated and stirred crystallizing vessel, or the pyrolysis crystallization apparatus includes an external circulation heated crystallizer.

[0037] Preferably, the jacketed heating and stirring crystallizing vessel is equipped with a stirring device.

[0038] Preferably, the external circulation heating crystallizer comprises, in sequence, a shell-and-tube heat exchanger and a stirred crystallizer.

[0039] Preferably, the pyrolysis carbon dioxide discharge port is connected to the carbon dioxide intake port of the Chinese Churi jet in the three-phase reverse extraction device.

[0040] Preferably, a demister and a condenser are sequentially installed at the pyrolysis carbon dioxide discharge port.

[0041] Preferably, the pyrolysis carbon dioxide discharge port is connected to the carbon dioxide intake port of the Churley jet in the three-phase reverse extraction device via a one-way valve.

[0042] Preferably, the system further includes a solid-liquid separation device, the lithium carbonate slurry outlet is connected to the solid-liquid separation device, and the solid-liquid separation device is provided with a lithium carbonate solid phase outlet and a pyrolysis mother liquor outlet.

[0043] Preferably, the outlet of the pyrolysis mother liquor is connected to the liquid phase inlet of the Chinese Churi jet in the three-phase reverse extraction device.

[0044] Preferably, the solid-liquid separation device includes any one or a combination of at least two of a centrifuge, a belt filter, or a plate and frame filter press.

[0045] Preferably, the system further includes a washing device for washing the lithium carbonate solid phase and a drying device for drying the lithium carbonate solid phase.

[0046] In a second aspect, the present invention provides a method for co-producing lithium carbonate by CO2 back-extraction, wherein the method is carried out using the apparatus for co-producing lithium carbonate by CO2 back-extraction as described in the second aspect, or using the triple back-extraction apparatus as described in the first aspect.

[0047] Preferably, the method includes: A mixture of lithium-loaded organic phase and aqueous phase is fed into the liquid phase inlet of a Venturi jet injector. When the mixture passes through the throat, a negative pressure is generated, which draws carbon dioxide from the carbon dioxide inlet into the throat and disperses the carbon dioxide into microbubbles, which are then mixed with the mixture. The resulting three-phase mixture is then sent to a back-extraction tower for three-phase back-extraction treatment.

[0048] Preferably, the flow rate of the mixed liquid phase passing through the throat is 5~15m / s, more preferably 10~15m / s.

[0049] Preferably, the negative pressure generated in the throat ranges from -0.01 to -0.05 MPa.

[0050] Preferably, the volumetric flow rate ratio of the carbon dioxide to the mixed liquid phase is (0.2~5):1, and more preferably (0.5~3):1.

[0051] Preferably, the volumetric flow rate ratio of the lithium-loaded organic phase to the aqueous phase is (2~10):1, and more preferably (3~6):1.

[0052] Preferably, the lithium-supported organic phase contains lithium and an organic extraction system.

[0053] Preferably, the organic extraction system includes a β-diketone extractant, a co-extractant, and a diluent.

[0054] Preferably, the β-diketone extractant includes any one or a combination of at least two of benzoyltrifluoroacetone, thiophenecarboxyltrifluoroacetone, dibenzoylmethane, 2-naphthoyltrifluoroacetone, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone, acetylacetone, or dipentanoylmethane.

[0055] Preferably, the co-extractant comprises any one or a combination of at least two of the following: tributyl phosphate, trioctylphosphine oxide, trialkylphosphine oxide, di(2-ethylhexyl) 2-ethylhexylphosphonate, triisooctyl phosphate, N,N-dimethylformamide, N,N-dibutylacetamide, dimethyl sulfoxide, 1-methyl-2-pyrrolidone, or tributyl phosphate.

[0056] Preferably, the diluent comprises any one or a combination of at least two of the following: kerosene, sulfonated kerosene, n-hexane, n-heptane, isooctane, cyclohexane, toluene, xylene, dichloromethane, chloroform, carbon tetrachloride, ethyl acetate, or butyl butyrate.

[0057] Preferably, the concentration of β-diketone extractant in the lithium-loaded organic phase is 15-35 wt%.

[0058] Preferably, the concentration of the co-extractant in the lithium-loaded organic phase is 10-20 wt%.

[0059] Preferably, the aqueous phase includes makeup water and / or pyrolysis mother liquor.

[0060] Preferably, the three-phase back-extraction process includes: uniformly spraying the three-phase mixture from the liquid distributor onto the packing layer, forming a liquid film on the surface of the packing and performing back-extraction to obtain the back-extracted mixture.

[0061] Preferably, the temperature of the triple reverse extraction process is 15~45℃.

[0062] Preferably, the pressure of the triple reverse extraction process is 0.01~0.1 MPa.

[0063] Preferably, the liquid spray density in the three-phase reverse extraction process is 5~40 m³ / s.3 / (m 2 ·h).

[0064] Preferably, the residence time of the mixed liquid phase in the three-phase reverse extraction process is 5 to 20 minutes.

[0065] Preferably, in the three-phase back-extraction process, supplementary carbon dioxide is also introduced from the bottom of the packing layer to countercurrently contact the downwardly conveyed three-phase mixture for back-extraction.

[0066] Preferably, the method further includes: feeding the mixture into an oil-water separator for oil-water separation to obtain a lithium bicarbonate solution and an extracted organic phase, and then feeding the lithium bicarbonate solution into a pyrolysis crystallization apparatus for pyrolysis crystallization to obtain a lithium carbonate slurry and pyrolyzed carbon dioxide.

[0067] Preferably, the back-extracted organic phase is recycled to the extraction process as the extraction system.

[0068] Preferably, the temperature of the pyrolysis crystallization is 65~95℃.

[0069] Preferably, the residence time for pyrolysis crystallization is 1 to 3 hours.

[0070] Preferably, the carbon dioxide discharge outlet of the pyrolysis is circulated to the carbon dioxide inlet of the Chinese Churi jet in the three-stage back-extraction device for use as back-extraction carbon dioxide.

[0071] Preferably, the method further includes: performing solid-liquid separation on the lithium carbonate slurry to obtain pyrolysis mother liquor and lithium carbonate solid phase, and sequentially washing and drying the lithium carbonate solid phase to obtain lithium carbonate product.

[0072] Preferably, the pyrolysis mother liquor is circulated to the liquid phase inlet and mixed with makeup water to form the aqueous phase.

[0073] The present invention does not impose any special restrictions on the solid-liquid separation in the above process. Any device and method known to those skilled in the art for solid-liquid separation can be used. It can also be adjusted according to the actual process. For example, it can be filtration, centrifugation or sedimentation separation, or a combination of different methods.

[0074] The present invention does not impose any special restrictions on the drying process described above. Any device and method known to those skilled in the art for drying can be used. Adjustments can also be made according to the actual process. For example, it can be air drying, vacuum drying, oven drying, or freeze drying, or a combination of different methods.

[0075] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The three-phase back-extraction device provided by the present invention can form a uniformly mixed liquid in the feeding stage by using a Venturi jet, which significantly improves the mass transfer and back-extraction effect.

[0076] (2) The CO2 back-extraction co-production lithium carbonate system and method provided by the present invention can significantly shorten the back-extraction time and improve the back-extraction efficiency. The efficiency of one back-extraction can preferably be increased to more than 97%, and the purity of the obtained lithium carbonate product is ≥99.5%, which meets the battery-grade lithium carbonate standard (YS / T582-2013) and has broad application prospects. Attached Figure Description

[0077] Figure 1 This is a schematic diagram of a system device for CO2 back-extraction and co-production of lithium carbonate provided in Embodiment 1 of the present invention.

[0078] Figure 2 yes Figure 1 A magnified schematic diagram of a Chinese-style jet injector.

[0079] In the diagram: 1. Venturi jet injector; 11. Contraction section; 111. Organic liquid phase contraction section; 112. Aqueous phase contraction section; 12. Throat; 13. Diffusion section; 2. Back-extraction tower; 21. Oxidation tower exhaust port; 22. Liquid distributor; 23. Packing layer; 24. Gas distributor; 25. Liquid collection section; 26. Mixed material discharge port; 27. Carbon dioxide inlet; 3. Oil-water phase separator; 31. Organic phase discharge port; 32. Lithium bicarbonate solution discharge port; 4. Pyrolysis crystallization device; 41. Demister; 42. Heating jacket; 43. Lithium carbonate slurry discharge port; 44. Pyrolysis carbon dioxide discharge port; 5. Solid-liquid separation device; 51. Pyrolysis mother liquor discharge port; 52. Lithium carbonate solid phase discharge port; 100. Fresh carbon dioxide inlet pipeline; 101. Flow monitor; 200. Fresh aqueous phase inlet pipeline. Detailed Implementation

[0080] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0081] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0082] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0083] Those skilled in the art should understand that the present invention necessarily includes the necessary pipelines, conventional valves and general pump equipment for achieving complete process, but the above content is not the main inventive point of the present invention. Those skilled in the art can add layouts based on process flow and equipment structure selection, and the present invention does not make any special requirements or specific limitations in this regard.

[0084] As a specific embodiment of the present invention, a three-stage back-extraction device is provided, which includes a Venturi jet and a back-extraction tower. Along the material conveying direction, the Venturi jet sequentially includes a converging section, a throat, and a diffuser section.

[0085] The front end of the contraction section is provided with an organic liquid phase inlet and an aqueous phase inlet, which return to the contraction section; or, the contraction section includes an organic liquid phase contraction section and an aqueous phase contraction section, which merge into the throat.

[0086] The larynx is provided with a carbon dioxide inlet on its side wall or front end, and the carbon dioxide inlet consists of several holes evenly distributed circumferentially to ensure that CO2 can be inhaled uniformly.

[0087] In triple back-extraction, the mass transfer rate at the phase interface and the overall uniformity of mass transfer significantly affect the back-extraction effect. This invention employs a Venturi jet injector. First, the aqueous and organic phases are mixed. Then, negative pressure formed at the throat directly draws carbon dioxide into the Venturi jet injector. The mixed liquid and gaseous fluids expand and break up each other, transforming the carbon dioxide into microbubbles and simultaneously forming an oil-water mixed film on their surface. Finally, this film enters the back-extraction tower in a metastable, emulsion-like form. This method significantly reduces gas-liquid mass transfer unevenness, thereby significantly improving back-extraction efficiency, shortening the back-extraction time, and increasing the first-pass back-extraction rate of lithium.

[0088] It is worth noting that the lithium-loaded organic phase and the aqueous phase are pre-combined via a Y-type tee before entering the venturi tube, or they enter the contraction section separately from two symmetrically arranged inlets.

[0089] In some specific embodiments, the contraction section is a tapered cone shape along the material conveying direction.

[0090] In some specific embodiments, the inner diameter of the inlet of the contraction section is 25~80mm, for example, it can be 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm or 80mm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0091] In some specific embodiments, the cone angle of the contraction section is 15~30°, for example, it can be 15°, 17°, 19°, 20°, 22°, 24°, 25°, 27°, 29° or 30°, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0092] The present invention preferably controls the cone angle of the contraction section within the above-mentioned range, which can effectively improve the acceleration effect of the mixed liquid phase, thereby making it more conducive to forming a metastable emulsion-like state, forming a liquid film on the surface of microbubbles, and subsequently producing an explosion effect when the bubbles rupture in the packing layer, thereby increasing turbulence and improving mass transfer.

[0093] In some specific embodiments, the throat is a cylindrical section of equal diameter.

[0094] In some specific embodiments, the inner diameter of the throat is 0.33 to 0.5 times the inner diameter of the inlet, for example, it can be 0.33 times, 0.35 times, 0.37 times, 0.39 times, 0.41 times, 0.43 times, 0.45 times, 0.47 times, 0.49 times or 0.5 times, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0095] The present invention preferably controls the inner diameter of the throat within the above-mentioned range, which is more conducive to the inhalation of carbon dioxide and the formation of a metastable emulsion-like state.

[0096] In some specific embodiments, the ratio of the length of the throat to the inner diameter of the throat is (1~3):1, for example, it can be 1:1, 1.3:1, 1.5:1, 1.7:1, 1.9:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1 or 3:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0097] In some specific embodiments, the diffusion section is a gradually expanding cone shape along the material conveying direction.

[0098] In some specific embodiments, the cone angle of the diffusion section is 7~15°, for example, it can be 7°, 7.4°, 8°, 8.7°, 9.4°, 10°, 11°, 12°, 13°, 14° or 15°, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0099] In some specific embodiments, the ratio of the outlet inner diameter of the diffuser section to the inlet inner diameter of the contraction section is (1.2~1.5):1, for example, it can be 1.2:1, 1.21:1, 1.22:1, 1.23:1, 1.25:1, 1.28:1, 1.3:1, 1.32:1, 1.35:1, 1.38:1, 1.4:1, 1.45:1 or 1.5:1, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0100] In some specific embodiments, the carbon dioxide inlet is connected to a carbon dioxide supply pipeline.

[0101] In some specific embodiments, the carbon dioxide inlet is connected to a carbon dioxide supply line via a one-way valve.

[0102] In some specific embodiments, the carbon dioxide supply pipeline is equipped with a flow monitor.

[0103] In this invention, the amount of carbon dioxide inhaled is comprehensively regulated by controlling the negative pressure in the throat and a flow monitor.

[0104] In some specific embodiments, the Venturi jet is made of 316L stainless steel or a corrosion-resistant alloy.

[0105] In some specific embodiments, the back-extraction tower includes a packed tower.

[0106] In some specific embodiments, the height-to-diameter ratio of the back-extraction tower is (3~10):1, for example, it can be 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably (4~8):1.

[0107] In some specific embodiments, the material of the back-extraction tower includes 316L stainless steel or corrosion-resistant alloy.

[0108] In some specific embodiments, the packed tower is provided with a packing layer inside.

[0109] In some specific embodiments, the packing material of the packing layer includes structured packing and / or random packing. Structured packing is preferred because it has good film-forming properties, low pressure drop, and high throughput.

[0110] In some specific embodiments, the structured packing includes wire mesh corrugated packing and / or perforated plate corrugated packing.

[0111] In some specific embodiments, the random packing includes any one or a combination of at least two of Pall rings, rectangular saddle rings, or stepped rings.

[0112] In some specific embodiments, the specific surface area of ​​the packing in the packing layer is 200~800m². 2 / m 3 For example, it could be 200m 2 / m 3 260m 2 / m 3 330m 2 / m 3 400m 2 / m 3 460m 2 / m 3 530m 2 / m 3 600m 2 / m 3 660m 2 / m 3 730m 2 / m 3 or 800m 2 / m 3 The values ​​may vary, but are not limited to those listed. Other unlisted values ​​within this range also apply, with 350~500m being the preferred value. 2 / m 3 .

[0113] This invention selects suitable fillers and works in synergy with the metastable emulsion formed by the Venturi jet injector. The metastable emulsion can form a liquid film on the surface of the filler, thereby enabling uniform and efficient back-extraction. The two work together to improve back-extraction efficiency and greatly shorten back-extraction time.

[0114] In some specific embodiments, the stripping tower is equipped with a liquid distributor, which is located above the packing layer and at the outlet of the Venturi jet. The three-phase premixed liquid drawn from the Venturi jet outlet is uniformly sprayed onto the upper surface of the packing layer.

[0115] In some specific embodiments, the top of the stripping tower is provided with an oxide tower exhaust port. Unreacted CO2 gas is discharged and recovered and recycled after gas-liquid separation.

[0116] In some specific embodiments, the back-extraction tower is further provided with a carbon dioxide replenishment inlet, and a gas distributor is also provided at the lower part of the packing layer, connected to the carbon dioxide replenishment inlet. This can be used to supplement CO2 to increase the back-extraction driving force.

[0117] In some specific embodiments, the bottom of the back-extraction tower is provided with a liquid collection section.

[0118] In some specific embodiments, the liquid collection section is provided with a mixture discharge port.

[0119] As a specific embodiment of the present invention, a system apparatus for CO2 back-extraction and co-production of lithium carbonate is provided, the system apparatus including the three-stage back-extraction apparatus described in any of the above specific embodiments.

[0120] In some specific embodiments, the system includes an oil-water phase separator and a pyrolysis crystallization device. The oil-water phase separator is connected to the mixture outlet of the collection section. An organic phase outlet is provided at the upper part of the oil-water phase separator, and a lithium bicarbonate solution outlet is provided at the lower part. The lithium bicarbonate solution outlet is connected to the pyrolysis crystallization device. The pyrolysis crystallization device includes a lithium carbonate slurry outlet and a pyrolysis carbon dioxide outlet.

[0121] The oil-water phase separator and the pyrolysis crystallizer are directly fed into the pyrolysis crystallizer without cooling or intermediate storage tanks.

[0122] In some specific embodiments, the pyrolysis crystallization device includes a jacketed heated and stirred crystallizing vessel, using heat transfer oil or steam as the heating medium; or the pyrolysis crystallization device includes an external circulation heated crystallizer, in which lithium bicarbonate solution is sent to a shell-and-tube heat exchanger for heating via an external circulation pump and then returned to the crystallizer, utilizing the circulating flow to achieve uniform heating and crystal suspension growth, suitable for high-volume processing scenarios.

[0123] In some specific embodiments, a stirring device is provided inside the jacketed heating and stirring crystallization vessel.

[0124] In some specific embodiments, the external circulation heating crystallizer sequentially includes a shell-and-tube heat exchanger and a stirred crystallizer.

[0125] In some specific embodiments, the pyrolysis carbon dioxide discharge port is connected to the carbon dioxide intake port of the Churley jet in the three-phase reverse extraction device.

[0126] In some specific embodiments, a demister and a condenser are sequentially installed at the pyrolysis carbon dioxide discharge port.

[0127] A CO2 collection pipe is installed at the top of the pyrolysis crystallization unit. The CO2 gas released during pyrolysis is demisted by a demister and condenser, and then connected to the CO2 inlet of a Venturi jet injector via a CO2 circulation pipeline and a one-way valve. Driven by the negative pressure at the Venturi throat, the pyrolysis CO2 is automatically drawn in to participate in back-extraction, eliminating the need for an additional CO2 compressor or delivery fan. The overall CO2 recycling rate within the system is ≥90%, requiring only a small amount of external replenishment after steady-state operation.

[0128] In some specific embodiments, the pyrolysis carbon dioxide discharge port is connected to the carbon dioxide intake port of the Churley jet in the three-phase reverse extraction device via a one-way valve.

[0129] In some specific embodiments, the system further includes a solid-liquid separation device, the lithium carbonate slurry outlet is connected to the solid-liquid separation device, and the solid-liquid separation device is provided with a lithium carbonate solid phase outlet and a pyrolysis mother liquor outlet.

[0130] In some specific embodiments, the pyrolysis mother liquor outlet is connected to the liquid phase inlet of the Venturi ejector in the three-stage back-extraction unit. The pyrolysis mother liquor (filtrate) is not discharged; it is entirely returned to the aqueous phase inlet of the Venturi ejector, where it is combined with makeup pure water and recycled for use as the back-extraction aqueous phase. During long-term operation, to prevent trace impurities (Na...) from being discharged... + K + (e.g.,) are enriched in the circulating mother liquor, and 5-10% of the circulating mother liquor can be discharged periodically (e.g., every 200-500 hours of operation) and an equal amount of pure water can be added.

[0131] In some specific embodiments, the solid-liquid separation device includes any one or a combination of at least two of a centrifuge, a belt filter, or a plate and frame filter press.

[0132] In some specific embodiments, the system apparatus further includes a washing device for washing the lithium carbonate solid phase and a drying device for drying the lithium carbonate solid phase.

[0133] As a specific embodiment of the present invention, a method for co-producing lithium carbonate by CO2 back-extraction is provided. The method is carried out using the apparatus for co-producing lithium carbonate by CO2 back-extraction as described in any of the above specific embodiments, or using the triple back-extraction apparatus as described in any of the above specific embodiments.

[0134] In some specific embodiments, the method includes: A mixture of lithium-loaded organic phase and aqueous phase is fed into the liquid phase inlet of a Venturi jet injector. When the mixture passes through the throat, a negative pressure is generated, which draws carbon dioxide from the carbon dioxide inlet into the throat and disperses the carbon dioxide into microbubbles, which are then mixed with the mixture. The resulting three-phase mixture is then sent to a back-extraction tower for three-phase back-extraction treatment.

[0135] In this invention, the lithium-loaded organic phase and the aqueous phase are pumped into the liquid inlet of the Venturi ejector. As the liquid passes through the Venturi throat at high speed, a negative pressure is generated, automatically drawing CO2 gas into the throat. Simultaneously, strong turbulent shear force disperses the CO2 gas into microbubbles, forcing the organic and aqueous phases into a highly dispersed state. The three-phase mixture achieves excellent pre-dispersion at the Venturi tube outlet, increasing the phase interface area compared to traditional direct feeding methods, thereby significantly improving the back-extraction efficiency.

[0136] Inside the packed tower, as the three-phase mixture flows downwards along the packing surface, pre-dispersed CO2 microbubbles continuously dissolve in the aqueous phase, while lithium ions undergo a back-extraction reaction at the organic-aqueous phase interface to generate LiHCO3, which then enters the aqueous phase. The liquid film thickness on the packing surface is tens to hundreds of micrometers, resulting in an extremely short mass transfer distance for lithium ions to diffuse from the interior of the organic phase droplets to the aqueous phase. This mass transfer efficiency is far higher than that of millimeter-sized droplets in traditional batch reactors.

[0137] In some specific embodiments, the flow velocity of the mixed liquid phase when passing through the throat is 5~15 m / s, for example, it can be 5 m / s, 8 m / s, 9 m / s, 10 m / s, 11 m / s, 12 m / s, 14 m / s or 15 m / s, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 10~15 m / s.

[0138] In some specific embodiments, the negative pressure generated by the throat is in the range of -0.01 to -0.05 MPa, for example, it can be -0.01 MPa, -0.015 MPa, -0.018 MPa, -0.02 MPa, -0.022 MPa, -0.025 MPa, -0.028 MPa, -0.03 MPa, -0.035 MPa, -0.04 MPa, -0.045 MPa or -0.05 MPa, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0139] In some specific embodiments, the volumetric flow rate ratio of the carbon dioxide to the mixed liquid phase is (0.2~5):1, for example, it can be 0.2:1, 0.8:1, 1.3:1, 1.8:1, 2.4:1, 2.9:1, 3.4:1, 4:1, 4.5:1 or 5:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably (0.5~3):1.

[0140] In some specific embodiments, the volume flow ratio of the lithium-loaded organic phase and the aqueous phase is (2~10):1, for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably (3~6):1.

[0141] In some specific embodiments, the lithium-loaded organic phase contains lithium and an organic extraction system.

[0142] In some specific embodiments, the organic extraction system includes a β-diketone extractant, a co-extractant, and a diluent.

[0143] In some specific embodiments, the β-diketone extractant includes any one or a combination of at least two of benzoyltrifluoroacetone, thiophenecarboxyltrifluoroacetone, dibenzoylmethane, 2-naphthoyltrifluoroacetone, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone, acetylacetone, or dipentanoylmethane, wherein typical but non-limiting combinations are combinations of benzoyltrifluoroacetone and thiophenecarboxyltrifluoroacetone, combinations of 2-naphthoyltrifluoroacetone and thiophenecarboxyltrifluoroacetone, combinations of acetylacetone and 2-naphthoyltrifluoroacetone, and combinations of benzoyltrifluoroacetone and dibenzoylmethane.

[0144] In some specific embodiments, the co-extractant comprises any one or a combination of at least two of the following: tributyl phosphate, trioctylphosphine oxide, trialkylphosphine oxide, di(2-ethylhexyl) 2-ethylhexylphosphonate, triisooctyl phosphate, N,N-dimethylformamide, N,N-dibutylacetamide, dimethyl sulfoxide, 1-methyl-2-pyrrolidone, or tributyl phosphate. Typical but non-limiting combinations include the combination of tributyl phosphate and trioctylphosphine oxide, the combination of triisooctyl phosphate and trioctylphosphine oxide, the combination of tributyl phosphate and di(2-ethylhexyl) 2-ethylhexylphosphine oxide, and the combination of tributyl phosphate and dimethyl sulfoxide.

[0145] In some specific embodiments, the diluent includes any one or a combination of at least two of kerosene, sulfonated kerosene, n-hexane, n-heptane, isooctane, cyclohexane, toluene, xylene, dichloromethane, chloroform, carbon tetrachloride, ethyl acetate, or butyl butyrate, wherein typical but not limiting combinations are combinations of kerosene and sulfonated kerosene, n-heptane and sulfonated kerosene, kerosene and n-heptane, carbon tetrachloride and sulfonated kerosene, and kerosene and dichloromethane.

[0146] In some specific embodiments, the concentration of the β-diketone extractant in the lithium-loaded organic phase is 15~35wt%, for example, it can be 15wt%, 18wt%, 20wt%, 25wt%, 28wt%, 30wt%, 32wt%, 34wt%, or 35wt%, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0147] In some specific embodiments, the concentration of the co-extractant in the lithium-loaded organic phase is 10~20wt%, for example, it can be 10wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, or 20wt%, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0148] In some specific embodiments, the aqueous phase includes makeup water and / or pyrolysis mother liquor.

[0149] In some specific embodiments, the three-phase back-extraction process includes: uniformly spraying the three-phase mixture from a liquid distributor onto the packing layer, forming a liquid film on the surface of the packing and performing back-extraction to obtain the back-extracted mixture.

[0150] In some specific embodiments, the temperature of the triple reverse extraction process is 15~45°C, for example, it can be 15°C, 19°C, 22°C, 25°C, 29°C, 32°C, 35°C, 39°C, 42°C or 45°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0151] In some specific embodiments, the pressure of the triple reverse extraction process is 0.01~0.1MPa, for example, it can be 0.01MPa, 0.02MPa, 0.03MPa, 0.04MPa, 0.05MPa, 0.06MPa, 0.07MPa, 0.08MPa, 0.09MPa or 0.1MPa, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0152] In some specific embodiments, the liquid spray density in the triple reverse extraction process is 5~40m³. 3 / (m2 ·h), for example, could be 5m 3 / (m 2 ·h), 9m 3 / (m 2 ·h), 13m 3 / (m 2 ·h), 17m 3 / (m 2 ·h), 21m 3 / (m 2 ·h), 25m 3 / (m 2 ·h), 29m 3 / (m 2 ·h), 33m 3 / (m 2 ·h), 37m 3 / (m 2 ·h) or 40m 3 / (m 2 •h) etc., but not limited to the listed values, other unlisted values ​​within this range also apply.

[0153] In some specific embodiments, the residence time of the mixed liquid phase in the three-phase reverse extraction process is 5 to 20 minutes, for example, it can be 5 minutes, 7 minutes, 9 minutes, 10 minutes, 12 minutes, 14 minutes, 15 minutes, 17 minutes, 19 minutes or 20 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0154] In some specific embodiments, the three-phase back-extraction process also involves introducing supplementary carbon dioxide from the bottom of the packing layer to countercurrently contact the downwardly conveyed three-phase mixture for back-extraction.

[0155] To further improve the back-extraction rate and lithium recovery rate, CO2 gas can be introduced from the bottom of the column to form a countercurrent contact with the downward-flowing liquid-liquid mixture, thereby increasing the driving force of the CO2 concentration gradient.

[0156] In some specific embodiments, the method further includes: feeding the mixture into an oil-water separator for oil-water separation to obtain a lithium bicarbonate solution and an extracted organic phase, and then feeding the lithium bicarbonate solution into a pyrolysis crystallization apparatus for pyrolysis crystallization to obtain a lithium carbonate slurry and pyrolyzed carbon dioxide.

[0157] In some specific embodiments, the back-extracted organic phase is recycled to the extraction process as an extraction system.

[0158] In some specific embodiments, the temperature of the pyrolysis crystallization is 65~95℃, for example, it can be 65℃, 69℃, 72℃, 75℃, 79℃, 82℃, 85℃, 89℃, 92℃ or 95℃, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0159] In some specific embodiments, the residence time for pyrolysis crystallization is 1 to 3 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.5 hours, 1.7 hours, 1.9 hours, 2 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.8 hours, or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0160] In some specific embodiments, the pyrolysis carbon dioxide discharge outlet is circulated to the carbon dioxide inlet of the Churley jet in the three-phase back-extraction device for use as back-extraction carbon dioxide.

[0161] In some specific embodiments, the method further includes: performing solid-liquid separation on lithium carbonate slurry to obtain pyrolysis mother liquor and lithium carbonate solid phase, and sequentially washing and drying the lithium carbonate solid phase to obtain lithium carbonate product.

[0162] In some specific embodiments, the pyrolysis mother liquor is circulated to the liquid phase inlet and mixed with makeup water to form an aqueous phase.

[0163] The following detailed description uses specific examples.

[0164] Example 1 This embodiment provides a three-stage back-extraction device, which includes a Venturi jet and a back-extraction tower; along the material conveying direction, the Venturi jet sequentially includes a converging section, a throat, and a diffusion section; the outlet of the diffusion section is connected to the material inlet of the back-extraction tower; The contraction section includes an organic liquid phase contraction section and an aqueous phase contraction section, which converge at the throat.

[0165] The side wall or front end of the throat is provided with a carbon dioxide inlet, which is a number of holes evenly distributed in the circumference.

[0166] The contraction section is a tapered cone along the material conveying direction; the inlet inner diameter of the contraction section is 40mm; the cone angle of the contraction section is 25°; the throat is a cylindrical section of equal diameter; the inner diameter of the throat is 0.4 times the inlet inner diameter; the ratio of the length of the throat to the inner diameter of the throat is 2:1; the diffusion section is a tapered cone along the material conveying direction; the cone angle of the diffusion section is 9°; the ratio of the outlet inner diameter of the diffusion section to the inlet inner diameter of the contraction section is 1.3:1; the carbon dioxide inlet is connected to a carbon dioxide supply pipeline; the carbon dioxide inlet is connected to a carbon dioxide supply pipeline through a one-way valve; the carbon dioxide supply pipeline is equipped with a flow monitor; the Venturi jet is made of 316L stainless steel.

[0167] The back-extraction tower includes a packed tower; the height-to-diameter ratio of the back-extraction tower is 5:1; the material of the back-extraction tower includes 316L stainless steel; the packed tower has a packing layer inside; the packing layer is structured packing; the structured packing includes corrugated metal wire mesh packing; the specific surface area of ​​the packing in the packing layer is 450 m². 2 / m 3 The height of the filler layer is 2m.

[0168] The back-extraction tower is equipped with a liquid distributor located on the upper part of the packing layer and at the outlet of the Venturi jet. A dioxide exhaust port is located at the top of the back-extraction tower. The back-extraction tower also has a carbon dioxide inlet, and a gas distributor connected to the carbon dioxide inlet is located at the lower part of the packing layer. A liquid collection section is located at the bottom of the back-extraction tower, and a mixed material outlet is located on the liquid collection section.

[0169] Example 2 This embodiment provides a three-phase reverse extraction apparatus, which differs from Embodiment 1 only in that: The contraction section is a tapered cone along the material conveying direction; the inlet inner diameter of the contraction section is 25mm; the cone angle of the contraction section is 15°; the throat is a cylindrical section of equal diameter; the inner diameter of the throat is 0.33 times the inlet inner diameter; the ratio of the length of the throat to the inner diameter of the throat is 3:1; the diffusion section is a tapered cone along the material conveying direction; the cone angle of the diffusion section is 15°; the ratio of the outlet inner diameter of the diffusion section to the inlet inner diameter of the contraction section is 1.2:1; the carbon dioxide inlet is connected to a carbon dioxide supply pipeline; the carbon dioxide inlet is connected to a carbon dioxide supply pipeline through a one-way valve; the carbon dioxide supply pipeline is equipped with a flow monitor; the Venturi jet is made of 316L stainless steel.

[0170] The stripping tower includes a packed tower; the height-to-diameter ratio of the stripping tower is 10:1; the material of the stripping tower includes 316L stainless steel; the packed tower has a packing layer inside; the packing layer is structured packing; the structured packing includes perforated corrugated packing; the specific surface area of ​​the packing in the packing layer is 350 m². 2 / m 33 The height of the filler layer is 6m.

[0171] The rest are the same as in Example 1, and will not be repeated here.

[0172] Example 3 This embodiment provides a three-phase reverse extraction apparatus, which differs from Embodiment 1 only in that: The contraction section is a tapered cone along the material conveying direction; the inlet inner diameter of the contraction section is 80mm; the cone angle of the contraction section is 30°; the throat is a cylindrical section of equal diameter; the inner diameter of the throat is 0.5 times the inlet inner diameter; the ratio of the length of the throat to the inner diameter of the throat is 1.5:1; the diffusion section is a tapered cone along the material conveying direction; the cone angle of the diffusion section is 7°; the ratio of the outlet inner diameter of the diffusion section to the inlet inner diameter of the contraction section is 1.5:1; the carbon dioxide inlet is connected to a carbon dioxide supply pipeline; the carbon dioxide inlet is connected to a carbon dioxide supply pipeline through a one-way valve; the carbon dioxide supply pipeline is equipped with a flow monitor; the Venturi jet is made of 316L stainless steel.

[0173] The stripping tower includes a packed tower; the height-to-diameter ratio of the stripping tower is 3:1; the material of the stripping tower includes 316L stainless steel; the packed tower has a packing layer inside; the packing layer is composed of random packing; the random packing is Pall rings; and the specific surface area of ​​the packing in the packing layer is 498 m². 2 / m 33 The height of the filler layer is 1m.

[0174] The rest are the same as in Example 1, and will not be repeated here.

[0175] Example 4 This embodiment provides a three-phase reverse extraction device. Except for the cone angle of the shrinkage section being 45°, the three-phase reverse extraction device is the same as that in Embodiment 1, and will not be described again here.

[0176] Example 5 This embodiment provides a three-phase reverse extraction device. Except for the cone angle of the shrinkage section being 10°, the three-phase reverse extraction device is the same as that in Embodiment 1, and will not be described again here.

[0177] Example 6 This embodiment provides a three-way reverse extraction device. Except for the inner diameter of the throat being 0.3 times the inner diameter of the inlet, the three-way reverse extraction device is the same as that in Embodiment 1, and will not be described again here.

[0178] Example 7 This embodiment provides a three-way reverse extraction device. Except for the inner diameter of the throat being 0.6 times the inner diameter of the inlet, the three-way reverse extraction device is the same as that in Embodiment 1, and will not be described again here.

[0179] Example 8 This embodiment provides a three-phase reverse extraction device. Except for the cone angle of the diffusion section being 20°, the three-phase reverse extraction device is the same as that in Embodiment 1, and will not be described again here.

[0180] Example 9 This embodiment provides a three-phase reverse extraction device, wherein the specific surface area of ​​the packing material in the packing layer of the three-phase reverse extraction device is 150 m². 2 / m 3 Except for the above, everything else is the same as in Example 1, and will not be repeated here.

[0181] Example 10 This embodiment provides a three-phase reverse extraction device, wherein the specific surface area of ​​the packing material in the packing layer of the three-phase reverse extraction device is 850 m². 2 / m 3 Except for the above, everything else is the same as in Example 1, and will not be repeated here.

[0182] Comparative Example 1 This comparative example provides a three-phase reverse extraction device. The three-phase reverse extraction device is the same as that in Example 1 except that it does not have a Venturi jet, but instead has an aqueous phase inlet, a lithium-loaded organic phase inlet and a carbon dioxide inlet, and a gas-liquid distributor is provided on the upper part of the packing layer. It will not be described again here.

[0183] Comparative Example 2 This comparative example provides a three-phase reverse extraction device. Except for the fact that the throat does not have a carbon dioxide intake port, but instead mixes the carbon dioxide with the liquid phase and sends it directly into the inlet of the contraction section of the Venturi jet, the three-phase reverse extraction device is the same as that in Example 1, and will not be described again here.

[0184] Application Example 1 This application example provides a system and method for CO2 back-extraction and co-production of lithium carbonate. The system includes the three-phase back-extraction apparatus described in Example 1. The system includes an oil-water phase separator and a pyrolysis crystallization apparatus. The oil-water phase separator is connected to the mixture outlet of the collection section. An organic phase outlet is located at the upper part of the oil-water phase separator, and a lithium bicarbonate solution outlet is located at the lower part. The lithium bicarbonate solution outlet is connected to the pyrolysis crystallization apparatus. The pyrolysis crystallization apparatus includes a lithium carbonate slurry outlet and a pyrolysis carbon dioxide outlet.

[0185] The pyrolysis crystallization apparatus includes a jacketed heated and stirred crystallizing vessel, or the pyrolysis crystallization apparatus includes an external circulation heated crystallizer; a stirring device is provided inside the jacketed heated and stirred crystallizing vessel. The pyrolysis carbon dioxide discharge port is connected to the carbon dioxide inlet of the Churi jet in the three-phase reverse extraction device; a demister and a condenser are sequentially installed at the pyrolysis carbon dioxide discharge port; the pyrolysis carbon dioxide discharge port and the carbon dioxide inlet of the Churi jet in the three-phase reverse extraction device are connected by a one-way valve.

[0186] The system also includes a solid-liquid separation device, the lithium carbonate slurry outlet is connected to the solid-liquid separation device, the solid-liquid separation device is provided with a lithium carbonate solid phase outlet and a pyrolysis mother liquor outlet; the pyrolysis mother liquor outlet is connected to the liquid phase inlet of the Churi jet in the three-phase reverse extraction device; the solid-liquid separation device is a belt filter; the system also includes a washing device for washing the lithium carbonate solid phase; and a drying device for drying the lithium carbonate solid phase.

[0187] The method includes: The volumetric flow rate ratio of the lithium-loaded organic phase to the aqueous phase is 5:1. A mixed liquid phase consisting of the lithium-loaded organic phase (containing lithium and an organic extraction system; the lithium concentration is 2.5 g / L, and the organic extraction system includes 30 wt% benzoyltrifluoroacetone, 16 wt% tributyl phosphate, and the remainder kerosene) and the aqueous phase (make-up water and / or pyrolysis mother liquor) is fed into the liquid phase inlet of a Venturi jet injector. The flow rate of the mixed liquid phase through the throat is 10 m / s, generating a negative pressure of -0.02 MPa. Carbon dioxide is drawn into the throat from the carbon dioxide inlet and simultaneously dispersed into microbubbles and mixed with the mixed liquid phase. The volumetric flow rate ratio of carbon dioxide to the mixed liquid phase is 1:1. The resulting three-phase mixture is sent to a back-extraction tower for three-phase back-extraction treatment.

[0188] The three-phase back-extraction process includes: uniformly spraying the three-phase mixture from a liquid distributor onto the packing layer at a liquid spray density of 25 m³ / s. 3 / (m 2•h) A liquid film is formed on the surface of the packing material, and back-extraction is performed at 35°C and 0.08MPa. The residence time of the mixed liquid phase is 15min, and the back-extracted mixture is obtained. In the three-phase back-extraction process, carbon dioxide is also introduced from the bottom of the packing layer to countercurrently contact the downwardly conveyed three-phase mixture for back-extraction.

[0189] The mixture is fed into an oil-water separator for oil-water separation, yielding a lithium bicarbonate solution and a back-extracted organic phase. The back-extracted organic phase is recycled to the extraction system. The lithium bicarbonate solution is then fed into a pyrolysis crystallization apparatus for pyrolysis crystallization at 80°C for 2 hours, yielding a lithium carbonate slurry and pyrolytic carbon dioxide. The lithium carbonate slurry undergoes solid-liquid separation to obtain a pyrolysis mother liquor and a lithium carbonate solid phase. The lithium carbonate solid phase is then washed and dried to obtain the lithium carbonate product.

[0190] The carbon dioxide discharge outlet of the pyrolysis is circulated to the carbon dioxide inlet of the Chinese Churi jet in the three-phase back-extraction device and used as back-extraction carbon dioxide; the mother liquor of pyrolysis is circulated to the liquid phase inlet and mixed with makeup water as the aqueous phase.

[0191] Application Example 2 This application example provides a system and method for CO2 back-extraction and co-production of lithium carbonate. The system and method for CO2 back-extraction and co-production of lithium carbonate includes the three-stage back-extraction device in Example 2, and the other devices are the same as in Application Example 1.

[0192] The method includes: The volumetric flow rate ratio of the lithium-loaded organic phase to the aqueous phase is 2:1. A mixed liquid phase consisting of lithium-loaded organic phase (containing lithium and an organic extraction system; the lithium concentration is 3.0 g / L, and the organic extraction system includes 35 wt% 2-naphthoyltrifluoroacetone, 10 wt% triisooctyl phosphate and the remainder sulfonated kerosene) and aqueous phase (make-up water and / or pyrolysis mother liquor) is fed into the liquid phase inlet of a Venturi jet injector. The flow rate of the mixed liquid phase through the throat is 15 m / s, generating a negative pressure of -0.05 MPa. Carbon dioxide is drawn into the throat from the carbon dioxide inlet and simultaneously dispersed into microbubbles and mixed with the mixed liquid phase. The volumetric flow rate ratio of carbon dioxide to the mixed liquid phase is 0.5:1. The resulting three-phase mixture is sent to a back-extraction tower for three-phase back-extraction treatment.

[0193] The three-phase back-extraction process includes: uniformly spraying the three-phase mixture from a liquid distributor onto the packing layer at a liquid spray density of 40 m³ / s. 3 / (m 2•h) A liquid film is formed on the surface of the packing material, and back-extraction is performed at 15°C and 0.1MPa. The residence time of the mixed liquid phase is 5min, and the back-extracted mixture is obtained. In the three-phase back-extraction process, carbon dioxide is also introduced from the bottom of the packing layer to countercurrently contact the downwardly conveyed three-phase mixture for back-extraction.

[0194] The mixture is fed into an oil-water separator for oil-water separation, yielding a lithium bicarbonate solution and a back-extracted organic phase. The back-extracted organic phase is recycled to the extraction system. The lithium bicarbonate solution is then fed into a pyrolysis crystallization apparatus for pyrolysis crystallization at 65°C for 3 hours, yielding a lithium carbonate slurry and pyrolytic carbon dioxide. The lithium carbonate slurry undergoes solid-liquid separation to obtain a pyrolysis mother liquor and a lithium carbonate solid phase. The lithium carbonate solid phase is then washed and dried to obtain the lithium carbonate product.

[0195] The carbon dioxide discharge outlet of the pyrolysis is circulated to the carbon dioxide inlet of the Chinese Churi jet in the three-phase back-extraction device and used as back-extraction carbon dioxide; the mother liquor of pyrolysis is circulated to the liquid phase inlet and mixed with makeup water as the aqueous phase.

[0196] Application Example 3 This application example provides a system and method for CO2 back-extraction and co-production of lithium carbonate. The system and method for CO2 back-extraction and co-production of lithium carbonate includes the three-stage back-extraction device in Example 3, and the other devices are the same as in Application Example 1.

[0197] The method includes: The volumetric flow rate ratio of the lithium-loaded organic phase to the aqueous phase is 10:1. A mixed liquid phase consisting of lithium-loaded organic phase (containing lithium and an organic extraction system; the lithium concentration is 2.3 g / L, and the organic extraction system includes 15 wt% 2-naphthoyltrifluoroacetone, 20 wt% triisooctyl phosphate and the remainder sulfonated kerosene) and aqueous phase (make-up water and / or pyrolysis mother liquor) is fed into the liquid phase inlet of a Venturi jet injector. The flow rate of the mixed liquid phase through the throat is 5 m / s, generating a negative pressure of -0.01 MPa. Carbon dioxide is drawn into the throat from the carbon dioxide inlet and simultaneously dispersed into microbubbles and mixed with the mixed liquid phase. The volumetric flow rate ratio of carbon dioxide to the mixed liquid phase is 3:1. The resulting three-phase mixture is sent to a back-extraction tower for three-phase back-extraction treatment.

[0198] The three-phase back-extraction process includes: uniformly spraying the three-phase mixture from a liquid distributor onto the packing layer at a liquid spray density of 5 m³ / s. 3 / (m 2•h) A thick liquid film is formed on the surface of the packing material, and back-extraction is performed at 45°C and 0.01MPa. The residence time of the mixed liquid phase is 20min, and the back-extracted mixture is obtained. In the three-phase back-extraction process, carbon dioxide is also introduced from the bottom of the packing layer to countercurrently contact the downwardly conveyed three-phase mixture for back-extraction.

[0199] The mixture is fed into an oil-water separator for oil-water separation, yielding a lithium bicarbonate solution and a back-extracted organic phase. The back-extracted organic phase is recycled to the extraction system. The lithium bicarbonate solution is then fed into a pyrolysis crystallization apparatus for pyrolysis crystallization at 95°C for 1 hour, yielding a lithium carbonate slurry and pyrolytic carbon dioxide. The lithium carbonate slurry undergoes solid-liquid separation to obtain a pyrolysis mother liquor and a lithium carbonate solid phase. The lithium carbonate solid phase is then washed and dried to obtain the lithium carbonate product.

[0200] The carbon dioxide discharge outlet of the pyrolysis is circulated to the carbon dioxide inlet of the Chinese Churi jet in the three-phase back-extraction device and used as back-extraction carbon dioxide; the mother liquor of pyrolysis is circulated to the liquid phase inlet and mixed with makeup water as the aqueous phase.

[0201] Application Examples 4-10 and Comparative Examples 1-2 Application Examples 4-10 and Comparative Examples 1-2 provide a system apparatus and method for CO2 back-extraction and co-production of lithium carbonate. Except for the use of the three-stage back-extraction apparatus in Examples 4-10 and Comparative Examples 1-2, the system apparatus for CO2 back-extraction and co-production of lithium carbonate is the same as that in Application Example 1, and will not be described again here.

[0202] Test method: Test the concentration of lithium bicarbonate solution and the oil phase content therein, and calculate the first back-extraction rate.

[0203] The test results of the above application examples and application comparison examples are shown in Table 1.

[0204] Table 1 The following points can be observed from Table 1: (1) As can be seen from the comprehensive application examples 1 to 3, the three-stage back-extraction device provided by the present invention can significantly improve the back-extraction efficiency, with the single-stage back-extraction rate being above 98.2%, and has broad application prospects.

[0205] (2) Combining Application Examples 1 and 4-5, it can be seen that the cone angle of the shrinkage section in Application Example 1 is 25°. Compared with the cone angles of 45° and 10° in Application Examples 4-5, the single-pass extraction rate in Application Example 1 is 98.5%, while the single-pass extraction rates in Application Examples 4-5 are 97.2% and 95.2%, respectively. This shows that the present invention preferably controls the cone angle of the shrinkage section within a reasonable range, which can better improve the extraction efficiency and achieve a high single-pass extraction rate in a short time.

[0206] (3) Combining Application Examples 1 and 6-7, it can be seen that in Application Example 1, the inner diameter of the throat is 0.4 times the inner diameter of the inlet. Compared with Application Examples 4-5, where the inner diameter of the throat is 0.3 times and 0.6 times the inner diameter of the inlet, the single-pass extraction rate in Application Example 1 is 98.5%, while the single-pass extraction rates in Application Examples 6-7 are 97.3% and 94.2%, respectively. This shows that the present invention preferably controls the ratio of the inner diameter of the throat to the inner diameter of the inlet within a reasonable range, which can better improve the extraction efficiency and achieve a high single-pass extraction rate in a short time.

[0207] (4) Combining Application Examples 1 and 8, it can be seen that the cone angle of the diffusion section in Application Example 1 is 9°, compared to the cone angle of 20° in Application Example 8. The single-pass extraction rate in Application Example 1 is 98.5%, while the single-pass extraction rate in Application Example 8 is 89.5%. This shows that the present invention preferably controls the cone angle of the diffusion section within a reasonable range, which can better improve the extraction efficiency and achieve a high single-pass extraction rate in a short time.

[0208] (5) Combining Application Example 1 and Application Examples 9-10, it can be seen that the specific surface area of ​​the packing in Application Example 1 is 450 m². 2 / m 3 Compared to the packing with a specific surface area of ​​150 m² in Application Examples 9-10, 2 / m 3 and 850m 2 / m 3 In Application Example 1, the single-pass extraction rate was 98.5%, while in Application Examples 9 and 10, the single-pass extraction rates were 88.7% and 97.7%, respectively, and the pressure drop increased significantly in Application Example 10. This indicates that the present invention preferably controls the specific surface area of ​​the packing within a reasonable range, which can better improve the extraction efficiency and achieve a high single-pass extraction rate in a short time.

[0209] (6) In Comparative Example 1, the absence of a Venturi ejector resulted in a first-pass extraction rate of only 80.6% within the same timeframe, a significant decrease compared to Comparative Example 1. In Comparative Example 2, carbon dioxide was mixed with the liquid phase and directly fed into the inlet of the contraction section of the Venturi ejector. This significantly reduced the mixing and dispersion effect on the material, making it difficult to form a uniformly distributed liquid film on the bubble surface, ultimately leading to a significant decrease in the first-pass extraction rate to 84.3%. This demonstrates that the present invention, by combining a Venturi ejector with a back-extraction tower, can significantly improve the first-pass extraction rate, shorten the back-extraction time, and increase production efficiency.

[0210] In summary, the system and method for CO2 back-extraction and co-production of lithium carbonate provided by this invention can significantly shorten the back-extraction time and improve the back-extraction efficiency. The efficiency of a single back-extraction can preferably be increased to over 97%, and the purity of the obtained lithium carbonate product is ≥99.5%, meeting the battery-grade lithium carbonate standard (YS / T582-2013), with broad application prospects.

[0211] The present invention has been illustrated with the above embodiments to illustrate its detailed features, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the selected technical features, additions of auxiliary technical features, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A three-phase reverse extraction apparatus, characterized in that, The three-stage back-extraction device includes a Venturi jet injector and a back-extraction tower; Along the material conveying direction, the Venturi jet includes a converging section, a throat, and a diffuser section in sequence; the outlet of the diffuser section is connected to the material inlet of the stripping tower. The front end of the contraction section is provided with an organic liquid phase inlet and an aqueous phase inlet, which return to the contraction section; or, the contraction section includes an organic liquid phase contraction section and an aqueous phase contraction section, which merge into the throat. The side wall or front end of the throat is provided with a carbon dioxide inlet, which is a number of holes evenly distributed in the circumference.

2. The three-phase reverse extraction apparatus according to claim 1, characterized in that, The contraction section is a gradually tapering cone shape along the material conveying direction; Preferably, the inner diameter of the inlet of the contraction section is 25~80mm; Preferably, the cone angle of the contraction section is 15~30°; Preferably, the throat is a cylindrical section of equal diameter; Preferably, the inner diameter of the throat is 0.33 to 0.5 times the inner diameter of the inlet; Preferably, the ratio of the length of the larynx to the inner diameter of the larynx is (1~3):1; Preferably, the diffusion section is a gradually expanding cone shape along the material conveying direction; Preferably, the cone angle of the diffusion section is 7~15°; Preferably, the ratio of the outlet inner diameter of the diffuser section to the inlet inner diameter of the contraction section is (1.2~1.5):1; Preferably, the carbon dioxide inlet is connected to a carbon dioxide supply pipeline; Preferably, the carbon dioxide inlet is connected to a carbon dioxide supply pipeline via a one-way valve; Preferably, the carbon dioxide supply pipeline is equipped with a flow monitor; Preferably, the material of the Venturi jet includes 316L stainless steel or corrosion-resistant alloy material.

3. The three-phase reverse extraction apparatus according to claim 1 or 2, characterized in that, The stripping tower includes a packed tower; Preferably, the height-to-diameter ratio of the back-extraction tower is (3~10):1, more preferably (4~8):1; Preferably, the material of the back-extraction tower includes 316L stainless steel or a corrosion-resistant alloy; Preferably, the packed tower has a packing layer inside; Preferably, the packing material in the packing layer includes structured packing and / or random packing; Preferably, the structured packing includes wire mesh corrugated packing and / or perforated plate corrugated packing; Preferably, the random packing includes any one or a combination of at least two of Pall rings, rectangular saddle rings, or stepped rings; Preferably, the specific surface area of ​​the packing material in the packing layer is 200~800m². 2 / m 3 Preferably 350~500m 2 / m 3 ; Preferably, the back-extraction tower is provided with a liquid distributor, which is located on the upper part of the packing layer and at the outlet of the Venturi jet. Preferably, the top of the back-extraction tower is provided with an oxide tower exhaust port; Preferably, the stripping tower is further provided with a carbon dioxide inlet, and a gas distributor is provided at the bottom of the packing layer, which is connected to the carbon dioxide inlet; Preferably, the bottom of the back-extraction tower is provided with a liquid collection section; Preferably, the liquid collection section is provided with a mixture discharge port.

4. A system apparatus for CO2 back-extraction and co-production of lithium carbonate, characterized in that, The system apparatus includes the triple reverse extraction apparatus according to any one of claims 1 to 3.

5. The system apparatus according to claim 4, characterized in that, The system includes an oil-water phase separator and a pyrolysis crystallization device; the oil-water phase separator is connected to the mixed material outlet of the liquid collection section; the upper part of the oil-water phase separator is provided with an organic phase outlet, and the lower part is provided with a lithium bicarbonate solution outlet; the lithium bicarbonate solution outlet is connected to the pyrolysis crystallization device; the pyrolysis crystallization device includes a lithium carbonate slurry outlet and a pyrolysis carbon dioxide outlet.

6. The system apparatus according to claim 5, characterized in that, The pyrolysis crystallization apparatus includes a jacketed heated and stirred crystallizing vessel, or the pyrolysis crystallization apparatus includes an external circulation heated crystallizer; Preferably, the jacketed heating and stirring crystallizing vessel is equipped with a stirring device; Preferably, the external circulation heating crystallizer comprises, in sequence, a shell-and-tube heat exchanger and a stirred crystallizer; Preferably, the pyrolysis carbon dioxide discharge port is connected to the carbon dioxide intake port of the Churley jet in the three-phase reverse extraction device; Preferably, a demister and a condenser are sequentially installed at the pyrolysis carbon dioxide discharge port; Preferably, the pyrolysis carbon dioxide discharge port is connected to the carbon dioxide intake port of the Churley jet in the three-phase reverse extraction device via a one-way valve; Preferably, the system further includes a solid-liquid separation device, the lithium carbonate slurry outlet is connected to the solid-liquid separation device, and the solid-liquid separation device is provided with a lithium carbonate solid phase outlet and a pyrolysis mother liquor outlet; Preferably, the outlet of the pyrolysis mother liquor is connected to the liquid phase inlet of the Chinese Churi jet in the three-phase reverse extraction device; Preferably, the solid-liquid separation device includes any one or a combination of at least two of a centrifuge, a belt filter, or a plate and frame filter press; Preferably, the system further includes a washing device for washing the lithium carbonate solid phase; And a drying device for drying the lithium carbonate solid phase.

7. A method for co-producing lithium carbonate by CO2 back-extraction, characterized in that, The method is performed using the CO2 back-extraction apparatus according to any one of claims 4 to 6, or using the triple back-extraction apparatus according to any one of claims 1 to 3.

8. The method according to claim 7, characterized in that, The method includes: A mixture of lithium-loaded organic phase and aqueous phase is fed into the liquid phase inlet of a Venturi jet injector. When the mixture passes through the throat, a negative pressure is generated, which draws carbon dioxide from the carbon dioxide inlet into the throat and disperses the carbon dioxide into microbubbles, which are then mixed with the mixture. The resulting three-phase mixture is then sent to a back-extraction tower for three-phase back-extraction treatment.

9. The method according to claim 8, characterized in that, The flow velocity of the mixed liquid phase when passing through the throat is 5~15m / s, preferably 10~15m / s; Preferably, the negative pressure generated in the throat ranges from -0.01 to -0.05 MPa; Preferably, the volumetric flow rate ratio of the carbon dioxide to the mixed liquid phase is (0.2~5):1, more preferably (0.5~3):1; Preferably, the volumetric flow rate ratio of the lithium-loaded organic phase to the aqueous phase is (2~10):1, more preferably (3~6):1; Preferably, the lithium-supported organic phase contains lithium and an organic extraction system; Preferably, the organic extraction system includes a β-diketone extractant, a co-extractant, and a diluent; Preferably, the β-diketone extractant includes any one or a combination of at least two of benzoyltrifluoroacetone, thiophenecarboxyltrifluoroacetone, dibenzoylmethane, 2-naphthoyltrifluoroacetone, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone, acetylacetone, or dipentanoylmethane; Preferably, the co-extractant comprises any one or a combination of at least two of the following: tributyl phosphate, trioctylphosphine oxide, trialkylphosphine oxide, di(2-ethylhexyl) 2-ethylhexylphosphonate, triisooctyl phosphate, N,N-dimethylformamide, N,N-dibutylacetamide, dimethyl sulfoxide, 1-methyl-2-pyrrolidone, or tributyl phosphate. Preferably, the diluent comprises any one or a combination of at least two of the following: kerosene, sulfonated kerosene, n-hexane, n-heptane, isooctane, cyclohexane, toluene, xylene, dichloromethane, chloroform, carbon tetrachloride, ethyl acetate, or butyl butyrate. Preferably, the concentration of β-diketone extractant in the lithium-supported organic phase is 15-35 wt%. Preferably, the concentration of the co-extractant in the lithium-loaded organic phase is 10-20 wt%; Preferably, the aqueous phase includes makeup water and / or pyrolysis mother liquor; Preferably, the three-phase back-extraction process includes: uniformly spraying the three-phase mixture from the liquid distributor onto the packing layer, forming a liquid film on the surface of the packing and performing back-extraction to obtain the back-extracted mixture; Preferably, the temperature of the triple reverse extraction process is 15~45℃; Preferably, the pressure of the triple reverse extraction process is 0.01~0.1 MPa; Preferably, the liquid spray density in the three-phase reverse extraction process is 5~40 m³ / s. 3 / (m 2 ·h); Preferably, the residence time of the mixed liquid phase in the three-phase reverse extraction process is 5-20 min; Preferably, in the three-phase back-extraction process, supplementary carbon dioxide is also introduced from the bottom of the packing layer to countercurrently contact the downwardly conveyed three-phase mixture for back-extraction.

10. The method according to claim 8 or 9, characterized in that, The method further includes: feeding the mixture into an oil-water separator for oil-water separation to obtain a lithium bicarbonate solution and an extracted organic phase, and then feeding the lithium bicarbonate solution into a pyrolysis crystallization device for pyrolysis crystallization to obtain a lithium carbonate slurry and pyrolyzed carbon dioxide. Preferably, the back-extracted organic phase is recycled to the extraction process as the extraction system; Preferably, the temperature of the pyrolysis crystallization is 65~95℃; Preferably, the residence time for pyrolysis crystallization is 1-3 hours; Preferably, the carbon dioxide discharge outlet of the pyrolysis is circulated to the carbon dioxide inlet of the Churley jet in the three-phase back-extraction device for use as back-extraction carbon dioxide; Preferably, the method further includes: performing solid-liquid separation on the lithium carbonate slurry to obtain pyrolysis mother liquor and lithium carbonate solid phase, and washing and drying the lithium carbonate solid phase in sequence to obtain lithium carbonate product; Preferably, the pyrolysis mother liquor is circulated to the liquid phase inlet and mixed with makeup water to form the aqueous phase.

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