Method for extracting lithium from lithium precipitation mother liquor through centrifugal extraction

Abstract

The invention relates to the technical field of lithium precipitation mother liquor recovery, and discloses a method for extracting lithium from lithium precipitation mother liquor through centrifugal extraction, which comprises the following steps: S1, adjusting the pH value of the lithium precipitation mother liquor to 12.5-13.5 by using alkali liquor to obtain blended liquor; s2, performing countercurrent contact on the blended liquid and an organic extraction agent in a 2-5-stage serial centrifugal extractor according to an oil-water volume ratio of 1: 2-5: 1, and separating to obtain a lithium-loaded organic phase and raffinate; s3, performing countercurrent contact on the lithium-loaded organic phase and a washing agent in a 2-5-stage series centrifugal extractor according to a water-oil volume ratio of 1: 10-1: 1, and separating to obtain a washed organic phase and a washing solution containing impurities; and S4, mixing and contacting the washed organic phase with a stripping agent, and separating to obtain a lithium-rich water phase and a no-load organic phase. A multi-stage centrifugal extractor is adopted for counter-current extraction, washing, reverse extraction and organic phase regeneration, and the purpose of recycling lithium from complex mother liquor is achieved.

Description

Technical Field

[0001] This invention relates to the field of lithium precipitation mother liquor recovery technology, and in particular to a method for extracting lithium from lithium precipitation mother liquor by centrifugal extraction. Background Technology

[0002] The rapid development of new energy vehicles has increased the demand for energy metals such as lithium. In lithium carbonate production, the mother liquor after lithium precipitation still contains a large amount of metallic lithium, and direct discharge of this liquor would result in significant resource waste. Therefore, it is necessary to develop a green and efficient method for extracting lithium from lithium precipitation mother liquor.

[0003] CN 111268704B uses a method of reduced pressure evaporation and freeze crystallization to obtain lithium carbonate and sodium chloride crystals from lithium precipitation mother liquor. However, this method is energy-intensive and inefficient, and the obtained lithium carbonate product contains a large amount of sodium carbonate impurities, which require a complex impurity removal process to convert it into industrial-grade or battery-grade lithium carbonate.

[0004] CN 116829509 A describes an extraction method for recovering metallic lithium from lithium precipitation mother liquor. However, this method does not specify the preparation of the lithium precipitation mother liquor or the treatment of the empty extractant after back-extraction, which will seriously affect the final extraction effect. In addition, this method uses an intermittent feeding method, resulting in low processing efficiency.

[0005] In summary, current methods for lithium extraction from lithium precipitation mother liquor all have several shortcomings. Therefore, there is an urgent need to develop a low-energy-consumption, simple, green, and efficient method for lithium extraction from lithium precipitation mother liquor. Summary of the Invention

[0006] The present invention aims to provide a method for lithium extraction by centrifugation of lithium precipitation mother liquor to solve the above-mentioned technical problems.

[0007] The technical solution of the present invention is as follows: This invention provides a method for extracting lithium from lithium precipitation mother liquor by centrifugal extraction, comprising the following steps: S1, adjusting the pH of the lithium precipitation mother liquor to 12.5–13.5 with an alkaline solution to obtain a prepared solution; S2, subjecting the prepared solution to countercurrent contact with an organic extractant in a 2–5 stage series centrifugal extractor at an oil-to-water volume ratio of 1:2–5:1, to separate the lithium-loaded organic phase and raffinate; S3, subjecting the lithium-loaded organic phase to countercurrent contact with a detergent in a 2–5 stage series centrifugal extractor at a water-to-oil volume ratio of 1:10–1:1, to separate the washed organic phase and a washing liquid containing impurities; S4, subjecting the washed organic phase to a back-extraction agent, to separate the lithium-rich aqueous phase and the unloaded organic phase; S5, subjecting the unloaded organic phase to washing water in a centrifugal extractor at a water-to-oil volume ratio of 1:3–3:1, to separate the regenerated organic extractant and acidic wastewater.

[0008] According to one embodiment of the present invention, in step S4, the volume flow ratio of the back-extraction agent to the washed organic phase is 1:10–1:1; the alkaline solution is a sodium hydroxide solution; the lithium concentration of the lithium precipitation mother liquor is 1–5 g / L; the organic extractant includes a mixture of β-diketone extractants and sulfonated kerosene; the back-extraction agent is a 1–5 mol / L sulfuric acid solution, or pure water or tap water with continuously introduced carbon dioxide gas. When carbon dioxide aerated water is used as the back-extraction agent, the back-extraction is carried out in a stirred back-extraction tower or centrifugal extractor equipped with a gas distributor, and CO2 is continuously introduced.

[0009] According to one embodiment of the present invention, the method is implemented using a lithium extraction system based on a lithium mother liquor centrifugal extraction system. This system includes an extraction unit for liquid-liquid extraction, a washing section unit for washing the loaded organic phase, and a back-extraction unit for back-extraction and extractant regeneration. The equipment performing centrifugal extraction in the extraction unit, washing section unit, and back-extraction unit is the same equipment. This equipment includes a centrifugal separation device, a centrifugal effluent kinetic energy recovery device located at the heavy phase outlet of the centrifugal separation device, and a feeding device located at the inlet of the centrifugal separation device. The centrifugal separation device includes a frame and a drive motor mounted on the frame. A housing is fixedly installed inside the frame, and a drum is rotatably installed inside the housing via a rotating shaft. The working end of the drive motor is connected to the rotating shaft. Heavy phase inlets and light phase inlets are respectively located on both sides of the bottom of the housing. From top to bottom, heavy phase weirs and light phase weirs are sequentially arranged on the inner wall of the top of the drum. A heavy phase collection chamber is formed above the heavy phase weirs, and a light phase collection chamber is formed above the light phase weirs. A heavy phase outlet is formed on the heavy phase collection chamber, and a light phase outlet is formed on the light phase collection chamber.

[0010] According to one embodiment of the present invention, the centrifugal effluent kinetic energy recovery device includes a plurality of outlet cavities uniformly arranged circumferentially on and rotating synchronously with a heavy phase weir plate. The outlet cavities are divided into a double-layer structure by impact baffles, thereby forming a C-shaped path for the fluid inside the outlet cavities. The outlet of the C-shaped path forms a nozzle for ejecting fluid in the opposite direction to the rotation of the heavy phase weir plate, so that the reaction force of the fluid acts positively on the rotation of the outlet cavities. The inflection point of the C-shaped path forms a force-bearing surface for positively acting on the rotation of the outlet cavities under fluid impact. The force-bearing surface is an inclined surface provided on the inner wall of each outlet cavity. The direction points towards the nozzle side, and the spray direction of the nozzle is tangential to the circle formed by the rotation path of the outlet cavity. The outlet cavity has a streamlined head at the end away from the nozzle to reduce wind resistance. A guide hole communicating with the C-shaped path inlet is provided on the heavy phase weir plate. Guide plates with fixed positions are installed at intervals below the heavy phase weir plate. A guide cavity for collecting fluid on the side of the drum wall is formed between the heavy phase weir plate and the guide plates. A conical widening section is provided at the bottom of the drum below the heavy phase weir plate so that the liquid inside and outside the drum flows faster and is reflected into the guide hole under the action of the guide plate. The cross-section of the guide hole is a cone with a diameter that gradually increases from bottom to top.

[0011] According to one embodiment of the present invention, the feeding device includes a premixing chamber fixedly sleeved in the inlet region of a rotating drum, a rotating shaft passing through the rotating drum and extending into the premixing chamber with a secondary mixing device at its end, and a primary mixing device at the bottom of the premixing chamber. The rotating drum, premixing chamber, and rotating shaft are all driven by the same power source to rotate, so that the material is drawn into the premixing chamber through the gap between the outer shell and the premixing chamber, undergoes secondary mixing through the primary and secondary mixing devices, and then enters the rotating drum. The secondary mixing device is configured as a mixing impeller fixedly installed at the bottom end of the rotating shaft and synchronously driven by the rotating shaft, and the primary mixing device is configured as a centripetal impeller fixedly installed at the bottom end of the premixing chamber and synchronously driven by the premixing chamber. A reinforcing device is fixedly installed on the inner wall of the premixing chamber. A stirring impeller is provided to enhance the stirring effect by synchronously driving the stirring impeller to rotate within the premixing chamber. The bottom part of the drum extends into the premixing chamber and is equipped with a feed impeller for pumping fluid into the drum. The longitudinal section of the mixing impeller is tapered with a diameter that gradually increases from bottom to top. A spiral guide is fixedly fitted on the outer wall of the premixing chamber so that the spiral guide is synchronously driven to rotate within the premixing chamber, accelerating the downward flow of liquid in the gap between the outer shell and the premixing chamber. A mixing baffle is fixedly installed at the top of the outer wall of the premixing chamber to cooperate with the spiral guide to prevent the upward flow of liquid in the gap between the outer shell and the premixing chamber. A pressure impeller is fixedly connected to the top of the inner wall of the premixing chamber so that the liquid on the outer side of the premixing chamber is rotated back to the middle of the premixing chamber and sucked in.

[0012] According to one embodiment of the present invention, the extraction unit includes a material pipeline, a raffinate pipeline, a material storage tank, a material booster pump, an extractant pipeline, an extractant storage tank, an extractant booster pump, and a multi-stage centrifugal extractor, wherein the multi-stage centrifugal extractor is the same equipment as the described equipment; the material pipeline is sequentially connected to the material storage tank and the material booster pump, and then connected in series with the aqueous phase inlet and outlet of the first-stage to N-stage centrifugal extractor, and finally flows into the raffinate pipeline; the extractant pipeline is sequentially connected to the extractant storage tank and the extractant booster pump, and then connected in series with the organic phase inlet and outlet of the first-stage to N-stage centrifugal extractor, and finally discharged into the washing section unit.

[0013] According to one embodiment of the present invention, the washing section unit includes a washing pipeline, a detergent pipeline, a detergent storage tank, a detergent booster pump, and a multi-stage centrifugal extractor II, which is the same equipment as the washing section unit. The detergent pipeline is connected in sequence to the detergent storage tank and the detergent booster pump, and then connected in series with the water phase inlet and outlet of the first to Nth stage centrifugal extractors II, finally flowing into the washing residue pipeline. One end of the washing pipeline is connected to the discharge end of the extractant pipeline, and the other end is connected in series with the organic phase inlet and outlet of the first to Nth stage centrifugal extractors II, finally discharging into the back-extraction unit.

[0014] According to one embodiment of the present invention, the back-extraction unit includes a back-extraction inlet pipe, a carbon dioxide inlet pipe, a pure water inlet pipe, a homogenizing pump, a centrifugal extractor III, a mixed liquid pipeline, a mixed liquid booster pump, and multiple carbon dioxide reactors. The centrifugal extractor III is the same equipment as the aforementioned equipment. The carbon dioxide inlet pipe and the pure water inlet pipe are combined and connected in parallel to each carbon dioxide reactor through a pipeline equipped with a homogenizing pump. Each carbon dioxide reactor is equipped with a stirrer and a gas distributor. One end of the back-extraction inlet pipe is connected to the discharge end of the washing pipeline, and the other end of the back-extraction inlet pipe is connected in parallel to each carbon dioxide reactor. The discharge port of each carbon dioxide reactor is connected to the inlet of the centrifugal extractor III through a mixed liquid pipeline equipped with a mixed liquid booster pump. The aqueous phase outlet of the centrifugal extractor III is connected to the lithium bicarbonate product pipeline, and the organic phase outlet of the centrifugal extractor III is connected to the extractant storage tank through an unloaded organic phase return pipe.

[0015] According to one embodiment of the present invention, the system further includes a cleaning agent pipeline, a residual liquid drain pipe, a carbon dioxide recovery pipe, and a tail gas treatment pipeline; the top ends of each centrifugal extractor 1, centrifugal extractor 2, and centrifugal extractor 3 are all connected to the cleaning agent pipeline, and the drain ports at both ends of each centrifugal extractor 1, centrifugal extractor 2, and centrifugal extractor 3 are all connected to the residual liquid drain pipe, and the top end of each carbon dioxide reactor is connected to the carbon dioxide recovery pipe.

[0016] According to one embodiment of the present invention, the top of each centrifugal extractor 1, each centrifugal extractor 2, and each centrifugal extractor 3 is connected to the exhaust gas treatment pipeline; it also includes a supplementary pipeline and a backup pipeline; the supplementary pipeline is connected in parallel to the organic phase inlet of each centrifugal extractor 1; a backup pipeline is provided at the parallel connection of the extractant pipeline, material pipeline, washing pipeline, and detergent pipeline so that the machine to be repaired or maintained is skipped when centrifugal extractor 1 or centrifugal extractor 2 is under maintenance.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a method for lithium extraction from lithium precipitation mother liquor by centrifugal extraction. This method employs a multi-stage centrifugal extractor for countercurrent extraction, washing, back-extraction, and organic phase regeneration, achieving the goal of recovering lithium from complex mother liquor. The entire process is continuous and automated, with the extractant recycled, resulting in low energy and reagent consumption. The equipment is compact yet has a large processing capacity. The process is closed and safe, generating minimal waste. Overall, this invention provides an advanced process route for the resource recovery of lithium precipitation mother liquor, characterized by high recovery rate, high product purity, low operating cost, and environmental friendliness. The system used in this method of lithium extraction by centrifugal extraction of lithium mother liquor has the following advantages: First, this system integrates the back-extraction and washing functions into the same centrifugal extractor (centrifugal extractor three), and simultaneously regenerates the extractant for impurity cleaning through the CO2 aqueous solution back-extraction process (no separate washing section is required), reducing the number of devices; Second, in one embodiment of this system, strong acids are not used, and acidic wastewater is not generated. Instead, CO2 aqueous back-extraction is used to generate LiHCO3, and the CO2 released by thermal decomposition can be recycled, realizing a closed loop of CO2-lithium and eliminating acidic wastewater discharge; Third, the system robustness is significantly enhanced. This system achieves precise CO2 circulation through carbon dioxide recovery pipes and tail gas treatment pipes, avoiding gas waste, and the backup pipes support uninterrupted production during equipment maintenance, improving continuous operation stability. The back-extraction product LiHCO3 can be directly pyrolyzed to obtain electronic-grade Li2CO3, eliminating the sodium carbonate synthesis step. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of the system; Figure 2 This is a schematic diagram of a half-section structure of the preferred embodiment of the present invention; Figure 3 for Figure 2A magnified view of part A in the image; Figure 4 for Figure 2 A magnified view of part B in the image; Figure 5 for Figure 2 Longitudinal section of the middle guide flow cavity; Figure 6 for Figure 2 Top view of the central guide flow cavity.

[0020] In the diagram: 100, centrifugal separation equipment; 200, centrifugal effluent kinetic energy recovery device; 300, feeding device; 101, frame; 102, drive motor; 103, outer shell; 104, rotating shaft; 105, rotating drum; 105A, conical widening section; 106, heavy phase weir plate; 107, light phase weir plate; 108, heavy phase collection chamber; 109, light phase collection chamber; 110, heavy phase outlet; 111, light phase outlet; 112. Guide hole; 113. Heavy phase inlet; 114. Light phase inlet; 115. Feed impeller; 201. Outlet cavity; 202. Nozzle; 203. Head; 203A. Inclined surface; 204. Impact baffle; 205. Guide plate; 301. Premixing cavity; 302. Centripetal impeller; 303. Mixing impeller; 304. Enhanced stirring impeller; 305. Mixing baffle; 306. Spiral guide 307. Pressing impeller; 401. Material pipeline; 402. Raffinate pipeline; 403. Material storage tank; 404. Material booster pump; 405. Extractant pipeline; 406. Extractant storage tank; 407. Extractant booster pump; 408. Centrifugal extractor I; 409. Washing pipeline; 410. Detergent pipeline; 411. Detergent storage tank; 412. Detergent booster pump; 413. Centrifugal extractor II; 414. Back-extraction inlet pipe; 415. Carbon dioxide inlet pipe; 416. Pure water inlet pipe; 417. Homogenizer pump; 418. Centrifugal extractor III; 419. Mixed liquid pipeline; 420. Mixed liquid booster pump; 421. Carbon dioxide reactor; 422. Cleaning agent pipeline; 423. Residual liquid drain pipe; 424. Tail gas treatment pipeline; 425. Replenishment agent pipeline; 426. Backup pipeline; 427. Carbon dioxide recovery pipe. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] like Figure 1As shown, this invention provides a method for lithium extraction from lithium precipitation mother liquor by centrifugal extraction, comprising the following steps: S1, adjusting the pH of the lithium precipitation mother liquor to 12.5–13.5 with alkaline solution to obtain a prepared solution; S2, subjecting the prepared solution and an organic extractant to countercurrent contact in a 2–5 stage series centrifugal extractor at an oil-water volume ratio of 1:2–5:1 (i.e., countercurrent contact within the range of an oil-water volume ratio of 1:2 to 5:1), separating the lithium-loaded organic phase and the raffinate; S3, subjecting the lithium-loaded organic phase and a detergent to a 2–5 stage series centrifugal extraction process. In the machine, countercurrent contact is carried out at a water-to-oil volume ratio of 1:10–1:1 (i.e., countercurrent contact is carried out in the range of water-to-oil volume ratio from 1:10 to 1:1) to separate the washed organic phase and the washing liquid containing impurities; S4, the washed organic phase is mixed and contacted with the back-extraction agent to separate the lithium-rich aqueous phase and the empty organic phase; S5, the empty organic phase is contacted with the washing water in a centrifugal extractor at a water-to-oil volume ratio of 1:3–3:1 (contact is carried out in the range of water-to-oil volume ratio from 1:3 to 3:1) to separate the regenerated organic extractant and acidic wastewater.

[0023] According to one embodiment of the present invention, in step S4, the volume flow ratio of the back-extraction agent to the washed organic phase is 1:10–1:1 (the volume flow ratio is in the range of 1:10 to 1:1).

[0024] According to one embodiment of the present invention, the alkaline solution is a sodium hydroxide solution; the lithium concentration of the lithium precipitation mother liquor is 1–5 g / L; the organic extractant comprises a mixture of β-diketone extractants and sulfonated kerosene; the back-extraction agent is a 1–5 mol / L sulfuric acid solution, or pure water or tap water with continuously introduced carbon dioxide gas. When carbon dioxide aerated water is used as the back-extraction agent, the back-extraction is carried out in a stirred back-extraction tower or centrifugal extractor equipped with a gas distributor, and CO2 is continuously introduced.

[0025] According to one embodiment of the present invention, the method is implemented using a lithium extraction system based on centrifugal extraction of lithium mother liquor. The system includes an extraction unit for liquid-liquid extraction, a washing section unit for washing the loaded organic phase, and a back-extraction unit for back-extraction and extractant regeneration. The equipment performing centrifugal extraction in the extraction unit, washing section unit, and back-extraction unit is the same equipment.

[0026] The extraction unit includes a material pipeline 401, a raffinate pipeline 402, a material storage tank 403, a material booster pump 404, an extractant pipeline 405, an extractant storage tank 406, an extractant booster pump 407, and a multi-stage centrifugal extractor 408, which is the same equipment as this unit. The material pipeline 401 is connected in sequence to the material storage tank 403 and the material booster pump 404, and then connected in series with the water phase inlet and outlet of the first-stage to N-stage centrifugal extractor 408, finally flowing into the raffinate pipeline 402. The extractant pipeline 405 is connected in sequence to the extractant storage tank 406 and the extractant booster pump 407, and then connected in series with the organic phase inlet and outlet of the first-stage to N-stage centrifugal extractor 408, finally discharging into the washing section unit.

[0027] According to one embodiment of the present invention, the washing section unit includes a washing pipe 409, a detergent pipe 410, a detergent storage tank 411, a detergent booster pump 412, and a multi-stage centrifugal extractor 413, which is the same equipment as the washing section unit. The detergent pipe 410 is connected in sequence to the detergent storage tank 411 and the detergent booster pump 412, and then connected in series with the water phase inlet and outlet of the first to Nth stage centrifugal extractors 413, finally flowing into the washing residue pipe. One end of the washing pipe 409 is connected to the discharge end of the extractant pipe 405, and the other end is connected in series with the organic phase inlet and outlet of the first to Nth stage centrifugal extractors 413, finally discharging into the back-extraction unit.

[0028] According to one embodiment of the present invention, the back-extraction unit includes a back-extraction inlet pipe 414, a carbon dioxide inlet pipe 415, a pure water inlet pipe 416, a homogenizing pump 417, a centrifugal extractor 418, a mixed liquor pipeline 419, a mixed liquor booster pump 420, and multiple carbon dioxide reactors 421. The centrifugal extractor 418 is the same equipment as this unit. The carbon dioxide inlet pipe 415 and the pure water inlet pipe 416 are combined and connected in parallel to each carbon dioxide reactor 421 through a pipeline equipped with a homogenizing pump 417. Each carbon dioxide reactor 421 is equipped with a... A stirrer and a gas distributor are included. One end of the back-extraction inlet pipe 414 is connected to the discharge end of the washing pipe 409, and the other end of the back-extraction inlet pipe 414 is connected in parallel to each carbon dioxide reactor 421. The outlet of each carbon dioxide reactor 421 is connected to the inlet of the centrifugal extractor 418 through a mixed liquid pipeline 419 equipped with a mixed liquid booster pump 420. The aqueous phase outlet of the centrifugal extractor 418 is connected to the lithium bicarbonate product pipeline, and the organic phase outlet of the centrifugal extractor 418 is connected to the extractant storage tank 406 through an unloaded organic phase return pipe.

[0029] According to one embodiment of the present invention, the system further includes a cleaning agent pipeline 422, a residual liquid drain pipe 423, a carbon dioxide recovery pipe 427, and a tail gas treatment pipeline 424; the top ends of each centrifugal extractor 1 408, each centrifugal extractor 2 413, and each centrifugal extractor 3 418 are connected to the cleaning agent pipeline 422, and the drain ports at both ends of each centrifugal extractor 1 408, each centrifugal extractor 2 413, and each centrifugal extractor 3 418 are connected to the residual liquid drain pipe 423, and the top end of each carbon dioxide reactor 421 is connected to the carbon dioxide recovery pipe 427.

[0030] According to one embodiment of the present invention, the top ends of each centrifugal extractor 1 408, each centrifugal extractor 2 413 and each centrifugal extractor 3 418 are connected to the exhaust gas treatment pipe 424.

[0031] According to one embodiment of the present invention, it further includes a supplement pipe 425 and a spare pipe 426; the supplement pipe 425 is connected in parallel to the organic phase inlet of each centrifugal extractor 408; a spare pipe 426 is provided at the parallel connection of the extractant pipe 405, the material pipe 401, the washing pipe 409, and the washing pipe 410 so as to skip the machine being repaired or maintained when the centrifugal extractor 408 or the centrifugal extractor 413 is being repaired or maintained.

[0032] The working process of this system is as follows: The lithium precipitation mother liquor passes through the material storage tank 403 → material booster pump 404 → centrifugal extractor 408 aqueous phase inlet, and comes into contact with the organic phase from the extractant storage tank 406 via the extractant booster pump 407 → centrifugal extractor 408 organic phase inlet. The aqueous phase of the extract is then discharged through the centrifugal extractor 408 aqueous phase outlet → raffinate pipeline 402; the loaded organic phase passes through the centrifugal extractor 408 organic phase outlet → washing pipeline 409 → back-extraction inlet 414 → carbon dioxide reactor 421. Simultaneously, the CO2 aqueous solution flows through carbon dioxide inlet pipe 415 + pure water inlet pipe 416 → homogenizer pump 417 → carbon dioxide reactor 421. In the carbon dioxide reactor 421, the CO2 aqueous solution simultaneously achieves lithium back-extraction to generate LiHCO3 and organic phase cleaning. The lithium-rich aqueous phase flows through mixed liquid pipeline 419 → mixed liquid booster pump 420 → centrifugal extractor 3 418 → lithium bicarbonate product pipeline. The regenerated organic phase flows through centrifugal extractor 3 418 → empty organic phase return pipe back to extractant storage tank 406. The N-stage in this system is 3 stages.

[0033] like Figures 2 to 6As shown, centrifugal extractor 1 (408), centrifugal extractor 2 (413), and centrifugal extractor 3 (418) are the same equipment (referring to multi-stage series units with identical structure and function, used for continuous countercurrent extraction). This equipment includes a centrifugal separator 100 (core separator), a centrifugal liquid kinetic energy recovery device 200 (a rotating component used to recover liquid kinetic energy and convert it into auxiliary driving force) located at the heavy phase outlet 110 of the centrifugal separator 100, and a feeding device 300 (a pre-module used for material premixing and stable feeding) located at the inlet of the centrifugal separator 100. The centrifugal separator 100 includes a frame 101 (support frame, usually made of welded metal structure) and a drive motor 102 (main drive unit) mounted on the frame 101. An outer shell 103 (equipment outer cylinder, generally a metal shell) is fixedly installed inside the frame 101. A rotating drum 105 (high-speed rotating separation chamber, usually made of stainless steel) is rotatably mounted on a rotating shaft 104. The working end of the drive motor 102 is connected to the rotating shaft 104 via a drive (power is transmitted through a coupling or belt). Heavy phase inlet 113 and light phase inlet 114 (two-phase material input interface) are respectively provided on the bottom sides of the outer shell 103. From top to bottom, heavy phase weir plate 106 and light phase weir plate 107 (adjustable overflow weir ring, used to control the height of the two-phase separation interface) are arranged sequentially on the top inner wall of the rotating drum 105. A heavy phase collection chamber 108 (high-density phase temporary storage area) is formed above the heavy phase weir plate 106, and a light phase collection chamber 109 (low-density phase temporary storage area) is formed above the light phase weir plate 107. A heavy phase outlet 110 (heavy phase discharge channel) is formed on the heavy phase collection chamber 108, and a light phase outlet 111 (light phase discharge channel) is formed on the light phase collection chamber 109. The centrifugal effluent kinetic energy recovery device 200 includes multiple outlet chambers 201 (rotary kinetic energy recovery units, typically 4–8 in number) evenly arranged circumferentially on and synchronously rotating with the heavy phase weir plate 106. The outlet chambers 201 are divided into a double-layer structure (forming inner and outer flow channels) by impact baffles 204, thus creating a C-shaped path for the fluid inside the outlet chamber (the fluid first flows downward along the inner wall, then reverses and flows upward along the outer wall). The outlet of the C-shaped path forms a nozzle 202 for ejecting fluid in the opposite direction to the rotation of the heavy phase weir plate 106. The fluid reaction force acts positively on the rotation of the outlet cavity 201 (generating a torque to boost the drum) at the tangential injection port. The C-shaped path has a force-bearing surface formed at the bend to act positively on the rotation of the outlet cavity 201 under fluid impact. This force-bearing surface is an inclined surface 203A (an inclined guide surface that guides the fluid and transmits thrust) located on the inner wall of each outlet cavity 201. The incline of the inclined surface 203A points towards the nozzle 202 (ensuring smooth fluid flow to the nozzle). The injection direction of the nozzle 202 is towards the rotation path of the outlet cavity 201. The jetting direction is tangential to the circle formed by the diameter (spraying in the opposite direction along the tangent to maximize the recoil effect). A streamlined head 203 (drag-reducing leading edge, usually integrally machined) is formed at the end of the outlet cavity 201 away from the nozzle 202 to reduce wind resistance. A guide hole 112 (liquid inlet channel) is provided on the heavy phase weir plate 106, communicating with the C-shaped path inlet. Guide plates 205 (annular baffles) are installed at intervals below the heavy phase weir plate 106, with fixed positions relative to each other. A guide is formed between the heavy phase weir plate 106 and the guide plates 205 to collect the fluid from the wall side of the drum 105. The guide cavity (annular gap liquid collection area) and the drum 105 located below the heavy phase weir plate 106 are provided with a conical widening section 105A (this structure is designed to promote the accelerated flow of liquid and is usually machined as an integral part of the drum), so that the liquid inside and outside the drum 105 is accelerated and deflected into the guide hole 112 under the action of the guide plate 205 (the liquid is first accelerated in the conical area, then deflected by the guide plate, and then enters the guide hole to flow towards the kinetic energy recovery device). The cross section of the guide hole 112 is a cone with a diameter that gradually increases from bottom to top (to facilitate the smooth flow of high-speed fluid). The feeding device 300 includes a premixing chamber 301 (annular mixing chamber, coaxially arranged with the drum) fixedly sleeved in the inlet area of ​​the drum 105. A rotating shaft 104 passes through the drum 105 and extends into the premixing chamber 301, with a secondary mixing device (fine mixing component) at its end. A primary mixing device (coarse mixing component) is provided at the bottom of the premixing chamber 301. The drum 105, the premixing chamber 301, and the rotating shaft 104 are all driven by the same power source to rotate (synchronous rotation, compact structure, no need for additional sealing), so that the material is drawn into the premixing chamber 301 through the gap between the outer shell 103 and the premixing chamber 301, and after secondary mixing by the primary and secondary mixing devices, it enters the drum 105. The process involves the following steps: (1) Material flows in through the annular gap, undergoes initial mixing in the first stage, followed by fine homogenization in the second stage, and finally is pumped into the drum for separation. The second stage mixing device is configured as a mixing impeller 303 (conical stirring blades, enhancing shear dispersion) fixedly installed at the bottom of the rotating shaft 104 and synchronously driven by the shaft. The first stage mixing device is configured as a centripetal impeller 302 (radial suction structure, achieving centripetal convergence of materials) fixedly installed at the bottom of the premixing chamber 301 and synchronously driven by the chamber. Furthermore, an enhanced stirring impeller 304 (auxiliary turbulence blades) is fixedly installed on the inner wall of the premixing chamber 301, ensuring that the enhanced stirring impeller 304 is synchronously driven to rotate by the premixing chamber 301. The mixing effect is enhanced (the premixing chamber first drives the enhanced mixing impeller to rotate, then the agitation breaks the laminar flow, making the mixing more uniform); the bottom part of the drum 105 extends into the premixing chamber 301 and is provided with a feed impeller 115 (built-in feed impeller, which rotates synchronously with the drum to achieve active conveying) for pumping fluid into the drum 105; the longitudinal section of the mixing impeller 303 presents a cone shape with the diameter gradually increasing from bottom to top (inverted cone structure, which is conducive to guiding the material from the outside to the center); a spiral guide 306 (axial guide vanes) is fixedly sleeved on the outer wall of the premixing chamber 301 so that the spiral guide 306 is synchronously driven to rotate by the premixing chamber 301 to achieve the gap between the outer shell 103 and the premixing chamber 301. The liquid inside accelerates downward flow (first the spiral guide rotates, then pushes the liquid in the gap to quickly converge downward). A mixing baffle 305 (anti-backflow baffle) is fixedly installed on the top of the outer wall of the premixing chamber 301 to cooperate with the spiral guide 306 to prevent the liquid in the gap between the outer shell 103 and the premixing chamber 301 from flowing upward (first the baffle blocks the upward surge, then it works with the spiral guide to form a single downward flow channel). A pressure impeller 307 (radial return guide impeller) is fixedly connected to the top of the inner wall of the premixing chamber 301 so that the liquid on the outer side of the premixing chamber 301 is rotated to the middle of the premixing chamber 301 and sucked in (first the pressure impeller rotates to guide the outer peripheral liquid to the center, then promotes the material to smoothly enter the primary mixing device).

[0034] The working principle of this device is as follows: First, the heavy phase and light phase raw materials enter the annular flow channel between the premixing chamber 301 and the outer shell 103 through the heavy phase inlet 113 and the light phase inlet 114, respectively. Under the guidance and obstruction of the mixing baffle 305, the two-phase fluids flow axially downwards and generate initial tangential shear. At this time, the drive motor 102 starts, driving the drum 105 and the premixing chamber 301 fixedly connected to it to rotate synchronously at high speed through the rotating shaft 104. The spiral guide 306 provided on the outer wall of the premixing chamber 301 rotates accordingly, and its spiral blades generate a downward axial pumping force when rotating, forcing the fluid in the annular gap to be conveyed downwards, thereby ensuring that the material can be effectively captured by the centripetal impeller 302 located at the bottom. The centripetal impeller 302 rotates at high speed with the rotating shaft 104, generating a significant negative pressure in its inlet center region, which powerfully pumps the downward-conveyed two-phase fluid upwards into the center inlet at the bottom of the premixing chamber 301. This pumping process, accompanied by intense shearing and entrainment, completes the first discretization and preliminary mixing of the heavy and light phases.

[0035] Subsequently, the material entering from the bottom center of the premixing chamber 301 is immediately captured and subjected to a second high-intensity mixing by the coaxially mounted, suspended conical mixing impeller 303. The high-speed rotation of this impeller generates intense turbulence. Its unique conical structure not only enhances radial shear strength but also generates an axial force pointing towards the central axis of the drum 105, preferentially guiding the lighter, less dense phase upwards. This design ensures that the lighter phase tends to reach a higher liquid level before entering the main separation zone, effectively preventing secondary mixing and backmixing of the lighter phase with the settled heavier phase at the bottom of the drum 105, thus laying a fluid dynamic foundation for clear phase interface separation. Through the dedicated premixing chamber 301 located at the front end of the drum 105, this system completes two-stage progressive mixing within a compact, relatively enclosed high-intensity shear field before the material enters the main drum 105, significantly increasing the mass transfer surface area and mixing uniformity, creating excellent conditions for subsequent efficient extraction reactions.

[0036] Then, the mixture in the premixing chamber 301 is further sheared and homogenized by the reinforced stirring impeller 304 fixed inside the chamber, completing the third final mixing. Under the action of strong centrifugal force, some of the fluid that may be insufficiently mixed and rises along the inner wall of the premixing chamber 301 is forced to flow back to the middle of the chamber by the pressure impeller 307 rotating at the top of the chamber, forming an internal circulation to ensure that nothing is missed. Finally, all materials are sucked in by the feed impeller 115 at the bottom of the drum 105 and smoothly enter the main separation zone of the drum 105. The fluid entering the drum 105 rotates at high speed with the drum 105 and gradually rises along the axis. When it enters the tapered widening section 105A of the upper half of the drum 105 with a gradually expanding diameter, the separation environment is optimized in two ways: first, the separation radius increases, and according to the centrifugal force formula F_c = mω²r, the separation factor is significantly improved, and the separation driving force is enhanced; second, the tapered space provides a larger sedimentation storage volume for the heavy phase, reducing the risk of interface disturbance.

[0037] Inside the drum 105, the fluid rapidly stratifies under a centrifugal force field several times stronger than gravity: the heavy phase is thrown against the drum wall and flows upward along it; the light phase accumulates in the central region. The opening of the light phase weir 107 extends precisely to the light phase accumulation area, guiding the separated light phase to the light phase collection chamber 109, and finally discharging it from the light phase outlet 111. The heavy phase continues to rise along the drum wall, and after passing the top of the heavy phase weir 106, it is effectively captured by the guide plate 205 located on the separation side of the weir. The guide plate 205 smoothly guides the high-speed heavy phase fluid into the guide hole 112 (its tapered design, smaller at the bottom and larger at the top, facilitates fluid acceleration and stabilizes the flow rate), and then injects it into the outlet chamber 201. This chamber is precisely arranged along the tangential direction of the rotation circle of the drum 105 and is the core of kinetic energy conversion.

[0038] Within the outlet cavity 201, the high-speed fluid first impacts the fixed impact baffle 204, precisely splitting into two streams. One stream deflects to the left, entering the lower half of the nozzle 202, but the lower half of the nozzle 202 is closed, so subsequent water flow can only come from the other side; the other stream deflects to the right, first impacting the inclined surface 203A within the head 203. The inclined surface 203A decomposes the normal impact force of the fluid, generating a tangential component force, directly creating a positive driving torque on the cavity (i.e., the rotating drum 105). Subsequently, this stream of fluid bypasses the impact baffle 204 and is ejected from the upper half of the nozzle 202. All fluid ejected from the nozzle 202 has its ejection direction set opposite to the rotation direction of the rotating drum 105. According to Newton's third law, the reaction force generated by the jet stream again applies a strong positive torque to the rotating drum 105. The torque generated by the impact of the inclined plane 203A and the jet thrust is superimposed in the same direction, forming a significant auxiliary driving effect, directly reducing the load on the main drive motor 102 and achieving significant energy saving. The streamlined design of the cavity head 203 effectively reduces the wind resistance loss generated by friction with air during high-speed rotation. This invention has significant advantages over traditional centrifugal separators 100. Conventional designs typically reduce the flow rate of the separated liquid to prevent the high-speed liquid jet from generating reverse impact resistance on the drum 105, thereby avoiding overload or mechanical damage to the drive motor 102. However, this approach inherently consumes the kinetic energy carried by the liquid, resulting in energy waste and limiting the equipment's ability to handle high-flow-rate materials.

[0039] This invention innovatively incorporates a conical widening section 105A in the heavy phase outlet 110 region of the drum 105. This structure is not for deceleration, but rather utilizes the principle of centrifugal acceleration to further increase the flow velocity of the heavy phase liquid near the wall of the drum 105 as it flows through the conical widening section 105A. The accelerated high-speed liquid is guided by the guide plate 205, enters the C-shaped flow channel of the kinetic energy recovery device through the conical guide hole 112 on the heavy phase weir plate 106, and finally is ejected at high speed from the tangential nozzle 202 in the opposite direction to the rotation of the drum 105. According to the principle of conservation of momentum, the reaction torque generated by this reverse injection is consistent with the rotation direction of the drum 105, thereby actively propelling the drum 105 to rotate and achieving effective recovery and reuse of the liquid's kinetic energy.

[0040] Therefore, this invention not only avoids viewing liquid kinetic energy as a negative factor to be suppressed, but also transforms it into auxiliary driving energy, significantly reducing the load on the drive motor 102 and improving the overall energy efficiency. Simultaneously, because the liquid is efficiently extracted and participates in work, it also reduces turbulence and liquid film accumulation within the cavity, which is beneficial for improving separation clarity and processing throughput. This design concept breaks through the traditional passive protection approach of "deceleration and anti-impact," achieving a technological leap from "energy consumption" to "energy empowerment."

[0041] In summary, this embodiment ensures mass transfer and extraction efficiency through a compact and semi-enclosed stepped premixing system at the feed end. The design of the tapered drum 105 with a gradually expanding diameter optimizes the centrifugal separation force field and phase interface stability. Finally, a tangential kinetic energy recovery device integrated into the weir plate efficiently converts the kinetic energy of the high-pressure heavy phase fluid into mechanical energy to drive the rotation of the drum 105. The entire system achieves seamless integration and synergistic effect of the three functional modules: mixing, separation, and energy recovery, resulting in a dual improvement in system operating efficiency and energy utilization efficiency.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for lithium extraction from lithium precipitation mother liquor by centrifugal extraction, characterized in that, Includes the following steps: S1. Adjust the pH of the lithium precipitation mother liquor to 12.5–13.5 with alkaline solution to obtain the prepared solution; S2. The prepared liquid and the organic extractant are subjected to countercurrent contact in a centrifugal extractor with 2-5 stages connected in series at an oil-water volume ratio of 1:2-5:1 to separate the lithium-loaded organic phase and the raffinate. S3. The lithium-loaded organic phase and the detergent are subjected to countercurrent contact in a centrifugal extractor with 2-5 stages connected in series at a water-oil volume ratio of 1:10-1:1 to separate the washed organic phase and the washing liquid containing impurities. S4. The washed organic phase is mixed and contacted with the back-extraction agent to separate the lithium-rich aqueous phase and the empty organic phase. S5. The empty organic phase and the washing water are contacted in a centrifugal extractor at a water-oil volume ratio of 1:3–3:1 to separate the regenerated organic extractant and acidic wastewater.

2. The method for lithium extraction by centrifugal extraction from lithium precipitation mother liquor according to claim 1, characterized in that, In step S4, the volumetric flow rate ratio of the back-extraction agent to the washed organic phase is 1:10–1:1; the alkaline solution is a sodium hydroxide solution; the lithium concentration of the lithium precipitation mother liquor is 1–5 g / L; the organic extractant includes a mixture of β-diketone extractants and sulfonated kerosene; the back-extraction agent is a 1–5 mol / L sulfuric acid solution, or pure water or tap water with continuous carbon dioxide gas flow. When carbon dioxide aerated water is used as the back-extraction agent, the back-extraction is carried out in a stirred back-extraction tower or centrifugal extractor equipped with a gas distributor, and CO2 is continuously introduced.

3. The method for lithium extraction from lithium precipitation mother liquor by centrifugation according to claim 1 or 2, characterized in that, The method described herein employs a lithium extraction system using a centrifugal extraction system for lithium mother liquor. This system includes an extraction unit for liquid-liquid extraction, a washing section unit for washing the loaded organic phase, and a back-extraction unit for back-extraction and extractant regeneration. The equipment performing centrifugal extraction in the extraction unit, washing section unit, and back-extraction unit is the same equipment, which includes a centrifugal separator (100), a centrifugal effluent kinetic energy recovery device (200) located at the heavy phase outlet of the centrifugal separator (100), and a feeding device (300) located at the inlet of the centrifugal separator (100). The centrifugal separator (100) includes a frame (101) and a drive motor (102) mounted on the frame (101). A housing (103) is fixedly installed inside the frame (101). A drum (105) is rotatably mounted inside the housing (103) via a rotating shaft (104). The working end of the drive motor (102) is connected to the rotating shaft (104) for transmission. Heavy phase inlet (113) and light phase inlet (113) are respectively provided on both sides of the bottom of the housing (103). From top to bottom, a heavy phase weir plate (106) and a light phase weir plate (107) are sequentially arranged on the inner wall of the top of the drum (105). A heavy phase collection chamber (108) is formed above the heavy phase weir plate (106), and a light phase collection chamber (109) is formed above the light phase weir plate (107). A heavy phase outlet (110) is formed on the heavy phase collection chamber (108), and a light phase outlet (111) is formed on the light phase collection chamber (109).

4. The method for lithium extraction by centrifugal extraction from lithium precipitation mother liquor according to claim 3, characterized in that, The centrifugal effluent kinetic energy recovery device (200) includes multiple outlet chambers (201) evenly arranged circumferentially on the heavy phase weir plate (106) and rotating synchronously therewith. The outlet chambers (201) are divided into a double-layer structure by impact baffles (204), so that the fluid inside the outlet chambers forms a C-shaped path. The outlet of the C-shaped path forms a nozzle (202) for ejecting fluid in the opposite direction of rotation to the heavy phase weir plate (106), so that the reaction force of the fluid acts positively on the rotation of the outlet chambers (201). The inflection point of the C-shaped path forms a force-bearing surface for positively acting on the rotation of the outlet chambers (201) under the impact of the fluid. The force-bearing surface is an inclined surface (203A) set on the inner wall of each outlet chamber (201). The inflection direction of the inclined surface (203A) points towards the nozzle (202) side, and the ejection direction of the nozzle (202) is towards the direction of the nozzle. Tangentially to the circle formed by the rotation path of the outlet cavity (201), a streamlined head (203) is formed at the end of the outlet cavity (201) away from the nozzle (202) to reduce wind resistance. A guide hole (112) communicating with the C-shaped path inlet is provided on the heavy phase weir plate (106). Guide plates (205) with fixed positions are installed at intervals below the heavy phase weir plate (106). A guide cavity for receiving fluid on the wall side of the drum (105) is formed between the heavy phase weir plate (106) and the guide plate (205). A conical widening part (105A) is provided below the heavy phase weir plate (106) of the drum (105) so that the liquid inside and outside the drum (105) flows faster and is deflected into the guide hole (112) under the action of the guide plate (205). The cross section of the guide hole (112) is a cone with a diameter that gradually increases from bottom to top.

5. The method for lithium extraction by centrifugal extraction from lithium precipitation mother liquor according to claim 3, characterized in that, The feeding device (300) includes a premixing chamber (301) fixedly sleeved in the inlet area of ​​the drum (105). A rotating shaft (104) passes through the drum (105) and extends into the premixing chamber (301), with a secondary mixing device at its end. A primary mixing device is provided at the bottom of the premixing chamber (301). The drum (105), the premixing chamber (301), and the rotating shaft (104) are all driven by the same power source to rotate, so that the material is drawn into the premixing chamber through the gap between the outer shell (103) and the premixing chamber (301). The material is mixed twice, first by a primary mixing device and then by a secondary mixing device, before entering the drum (105). The secondary mixing device is configured as a mixing impeller (303) fixedly installed at the bottom of the rotating shaft (104) and synchronously driven by the rotating shaft (104). The primary mixing device is configured as a centripetal impeller (302) fixedly installed at the bottom of the premixing chamber (301) and synchronously driven by the premixing chamber (301). A reinforcing stirring impeller (304) is fixedly installed on the inner wall of the premixing chamber (301) to ensure that... The enhanced stirring impeller (304) is synchronously driven to rotate by the premixing chamber (301) to achieve enhanced stirring effect; the bottom part of the drum (105) extends into the premixing chamber (301) and is provided with a feed impeller (115) for pumping fluid into the drum (105) on this part; the longitudinal section of the mixing impeller (303) presents a cone shape with the diameter gradually increasing from bottom to top; a spiral guide (306) is fixedly sleeved on the outer wall of the premixing chamber (301) so that the spiral guide (306) is driven to rotate by the premixing chamber (301) Synchronous drive rotation accelerates the downward flow of liquid in the gap between the outer shell (103) and the premixing chamber (301). A mixing baffle (305) is fixedly installed on the top of the outer wall of the premixing chamber (301) to cooperate with the spiral guide (306) to prevent the liquid in the gap between the outer shell (103) and the premixing chamber (301) from flowing upward. A pressure impeller (307) is fixedly connected to the top of the inner wall of the premixing chamber (301) so that the liquid on the outer side of the premixing chamber (301) rotates back to the middle of the premixing chamber (301) and is sucked in.

6. The method for lithium extraction by centrifugal extraction from lithium precipitation mother liquor according to claim 5, characterized in that, The extraction unit includes a material pipeline (401), a raffinate pipeline (402), a material storage tank (403), a material booster pump (404), an extractant pipeline (405), an extractant storage tank (406), an extractant booster pump (407), and a multi-stage centrifugal extractor (408). The centrifugal extractor (408) is the same equipment as the described equipment. The material pipeline (401) is connected in sequence to the material storage tank (403) and the material lifting pump (404), and then connected in series with the water phase inlet and outlet of the first-stage to N-stage centrifugal extractor (408), and finally flows into the raffinate pipeline (402). The extractant pipeline (405) is connected in sequence to the extractant storage tank (406) and the extractant booster pump (407), and then connected in series with the organic phase inlet and outlet of the first-stage to N-stage centrifugal extractor (408), and finally discharged into the washing section unit.

7. The method for lithium extraction by centrifugal extraction from lithium precipitation mother liquor according to claim 6, characterized in that, The washing section unit includes a washing pipe (409), a detergent pipe (410), a detergent storage tank (411), a detergent booster pump (412), and a multi-stage centrifugal extractor II (413). The centrifugal extractor II (413) is the same equipment as the aforementioned equipment. The detergent pipeline (410) is connected in sequence to the detergent storage tank (411) and the detergent booster pump (412), and then connected in series with the water phase inlet and outlet of the first to Nth stage centrifugal extractor (413), and finally flows into the detergent residue pipeline. One end of the washing pipe (409) is connected to the discharge end of the extractant pipe (405), and the other end is connected in series with the organic phase inlet and outlet of the second centrifugal extractor (413) from stage I to stage N, and finally discharged into the back-extraction unit.

8. The method for lithium extraction by centrifugal extraction from lithium precipitation mother liquor according to claim 7, characterized in that, The back-extraction unit includes a back-extraction inlet pipe (414), a carbon dioxide inlet pipe (415), a pure water inlet pipe (416), a homogenizing pump (417), a centrifugal extractor three (418), a mixed liquid pipeline (419), a mixed liquid booster pump (420), and multiple carbon dioxide reactors (421). The centrifugal extractor three (418) is the same equipment as the aforementioned equipment. The carbon dioxide inlet pipe (415) and the pure water inlet pipe (416) are combined and then connected in parallel to each carbon dioxide reactor (421) through a pipe equipped with a homogenizing pump (417); each carbon dioxide reactor (421) is equipped with a stirrer and a gas distributor. One end of the back-extraction inlet pipe (414) is connected to the discharge end of the washing pipe (409), and the other end of the back-extraction inlet pipe (414) is connected in parallel to each carbon dioxide reactor (421). The discharge port of each carbon dioxide reactor (421) is connected to the inlet of the centrifugal extractor three (418) through the mixed liquid pipeline (419) equipped with the mixed liquid booster pump (420). The aqueous phase outlet of the centrifugal extractor three (418) is connected to the lithium bicarbonate product pipeline. The organic phase outlet of the centrifugal extractor three (418) is connected to the extractant storage tank (406) through the empty organic phase return pipe.

9. The method for lithium extraction by centrifugal extraction from lithium precipitation mother liquor according to claim 8, characterized in that, It also includes a cleaning agent pipeline (422), a residual liquid drain pipe (423), a carbon dioxide recovery pipe (427), and an exhaust gas treatment pipe (424). The top of each centrifugal extractor 1 (408), centrifugal extractor 2 (413), and centrifugal extractor 3 (418) is connected to the cleaning agent pipeline (422), and the drain ports at both ends of each centrifugal extractor 1 (408), centrifugal extractor 2 (413), and centrifugal extractor 3 (418) are connected to the residual liquid drain pipe (423). The top of each carbon dioxide reactor (421) is connected to the carbon dioxide recovery pipe (427).

10. The method for lithium extraction by centrifugal extraction from lithium precipitation mother liquor according to claim 9, characterized in that, The top of each centrifugal extractor 1 (408), each centrifugal extractor 2 (413), and each centrifugal extractor 3 (418) is connected to the exhaust gas treatment pipe (424); it also includes a supplement pipe (425) and a spare pipe (426); the supplement pipe (425) is connected in parallel to the organic phase inlet of each centrifugal extractor 1 (408); a spare pipe (426) is provided at the parallel connection of the extractant pipe (405), the material pipe (401), the washing pipe (409), and the washing pipe (410) so that the machine to be repaired or maintained can be skipped when centrifugal extractor 1 (408) or centrifugal extractor 2 (413) is under maintenance.

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