A hierarchical mixing co-precipitation reactor based on venturi effect

Abstract

This invention discloses a staged mixing co-precipitation reactor based on the Venturi effect, comprising a feed section and a contraction section, a rapid mixing reaction section, and a diffusion-stabilizing reaction section connected sequentially downstream of the feed section. The feed section includes a central tube, an inner sleeve, and an outer sleeve. The central tube serves as the feed channel for circulating slurry. The inner sleeve is fitted outside the central tube, forming a jacket with the central tube, which serves as the feed channel for metal salts and ammonia. The outer sleeve is fitted outside one side of the inner sleeve, forming an annular channel with the inner sleeve, which serves as the feed channel for alkali solution. The central tube has an integrally formed nozzle at its end, the nozzle being conical, and the nozzle outlet having a straight section. This invention offers fast mixing speed and uniform mixing, solving the problem of uneven local concentration in traditional equipment, and yielding a particle product with narrow particle size distribution, good sphericity, and more uniform elemental distribution.

Description

Technical Field

[0001] This invention relates to the field of equipment for preparing precursor materials for lithium-ion batteries, specifically a hierarchical mixing co-precipitation reactor based on the Venturi effect. Background Technology

[0002] Coprecipitation is a core technology for preparing high-performance lithium-ion battery cathode material precursors. Its key challenge lies in processing metal salt solutions, such as Ni... 2+ Co 2+ Mn 2+ Ammonia and alkaline solutions, such as NaOH, are rapidly and homogeneously mixed. Currently, continuous stirred tank reactors are commonly used in the co-precipitation process for preparing ternary cathode material precursors, such as NCM and NCA. However, this technology has some inherent drawbacks, such as: Reactants rely on mechanical stirring for macroscopic mixing, which makes it difficult to achieve instantaneous homogeneous mixing. Incomplete reactions in some areas can easily lead to localized areas of excessively high concentration, resulting in explosive secondary nucleation and a wider particle size distribution of the product. Simultaneous nucleation and crystal growth within a single reaction zone cause newly generated nuclei to compete with growing particles for reactants, resulting in a wider particle size distribution. The unstable shear force generated by mechanical stirring can easily break the growing crystal structure, leading to irregular particle morphology. The uneven distribution of shear force generated by traditional mechanical stirring results in large differences in crystal growth rates in different directions, forming irregular particles and causing instability in the specific surface area and compaction density of the final cathode material.

[0003] Therefore, there is an urgent need to develop a specialized reactor that can achieve instantaneous and uniform mixing and spatially separate the nucleation and growth processes. Summary of the Invention

[0004] The purpose of this invention is to provide a staged mixing co-precipitation reactor based on the Venturi effect to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A staged mixing coprecipitation reactor based on the Venturi effect includes a feed section and a contraction section, a rapid mixing reaction section, and a diffusion stabilization reaction section that are sequentially connected downstream of the feed section. The feeding section includes a central pipe, an inner sleeve, and an outer sleeve. The central pipe is the feeding channel for circulating slurry. The inner sleeve is fitted outside the central pipe and forms a jacket with the central pipe. The jacket is the feeding channel for metal salts and ammonia. The outer sleeve is fitted outside one side of the inner sleeve and forms an annular channel with the inner sleeve. The annular channel is the feeding channel for alkali solution. The end of the central pipe has an integrally formed nozzle. The nozzle is conical and has a straight section at its outlet.

[0006] Furthermore, the nozzle outlet is set at a cone angle of 10° to 25° in the contraction section, and the distance between the nozzle outlet and the inlet of the rapid mixing reaction section is 1 to 3 times the nozzle inlet diameter d1.

[0007] Furthermore, the mixing fast reaction section is a cylindrical channel, which is used to achieve forced fluid mixing and homogeneous crystal nucleus generation. The length-to-diameter ratio of the length L3 of the mixing fast reaction section to its internal diameter d3 is L3 / d3 = 5:1 to 15:1.

[0008] Furthermore, the diffusion-stabilized reaction section is a channel that expands downstream. The inlet diameter of the diffusion-stabilized reaction section is the same as the internal diameter d3 of the mixing-fast reaction section, and the outlet diameter of the diffusion-stabilized reaction section is d4. The expansion ratio of the diffusion-stabilized reaction section is d4 / d3 = 2-3:1.

[0009] Furthermore, the length L1 of the central tube is 2-5 times the inner diameter D1 of the central tube, and the nozzle inlet diameter d1 is the same as the inner diameter D1 of the central tube.

[0010] Furthermore, the length L2 of the inner sleeve is 2-5 times the inner diameter D2 of the inner sleeve, and the gap width δ1 between the inner sleeve and the central tube is 3mm to 15mm.

[0011] Furthermore, the length L3 of the outer sleeve is 1-3 times the inner diameter D3 of the outer sleeve, and the gap width δ2 between the outer sleeve and the inner sleeve is 2mm to 10mm.

[0012] Furthermore, the length of the straight section is 1mm to 5mm, which can effectively improve the stability of the flow field, reduce eddy and turbulent phenomena, reduce pressure loss, and make the slurry flow more smoothly; the nozzle outlet and the straight section have a smooth transition, and the diameter of the transition circle is 1 / 6 to 1 / 2 times the nozzle outlet diameter d2.

[0013] Furthermore, the nozzle cone angle α is 30° to 45°, and the angles of the inner sleeve and outer sleeve are consistent.

[0014] Furthermore, spiral swirl blades are evenly distributed on the inner wall of the jacket, and the spiral swirl blades are welded to the central tube.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This application adopts a three-layer coaxial sleeve staged feeding structure to realize the feeding of three fluids in the order of slurry, salt solution and alkali solution. The nozzle generates a high-speed jet and forms a negative pressure zone at the throat, which entrains the surrounding fluid and instantly shears and disperses it, ensuring that the three reactants are mixed evenly and quickly, thus solving the problem of uneven concentration in local areas of traditional equipment.

[0016] 2. The mixed fast reaction section of this application provides a high-shear, high-turbulence environment, which promotes homogeneous nucleation and controls the number and initial size of crystal nuclei. The cross-sectional area of ​​the diffusion stabilization reaction section gradually increases and the flow rate decreases, providing a stable low-shear environment specifically for crystal growth, avoiding secondary nucleation, and resulting in a precursor particle product with narrow particle size distribution, good sphericity, and more uniform element distribution. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the staged mixing co-precipitation reactor structure of the present invention; Figure 2 This is a schematic diagram of the feeding section in the staged mixing co-precipitation reactor structure of the present invention; Figure 3 This is a schematic diagram of the graded mixing coprecipitation reaction system of the present invention; In the picture: 1-Feeding section; 11-Center tube; 111-Nozzle; 112-Straight section; 12-Inner sleeve; 121-Jacket; 122 - Circular channel; 13-Outer tube; 2-Contraction segment; 3-Mixed rapid reaction section; 4-Diffusion-stabilized reaction section. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0019] Please see Figure 1-3This invention provides a staged mixing co-precipitation reactor based on the Venturi effect, comprising a feed section 1 and a converging section 2, a rapid mixing reaction section 3, and a diffusion stabilizing reaction section 4 connected sequentially downstream of the feed section 1. A transition circle is provided at the connection between the inner diameter of the feed section 1 and the converging section 2 to ensure no abrupt change in flow resistance during fluid introduction. A high-speed jet generates a negative pressure zone at the outlet of the converging section 2, forcibly entraining the surrounding fluid into the jet core region, achieving preliminary shear mixing. The rapid mixing reaction section 3 is a cylindrical channel used to achieve forced fluid mixing and homogeneous crystal nucleus generation. The length-to-diameter ratio of the rapid mixing reaction section 3 (L3) to its internal diameter (d3) is L3 / d3 = 5 to 15 / 1. This design ensures that the three fluids are uniformly mixed at the molecular level while rapidly reaching critical supersaturation, achieving homogeneous crystal nucleus generation. The diffusion-stabilizing reaction section 4 is a downstream-expanding channel. The inlet diameter of the diffusion-stabilizing reaction section 4 is the same as the internal diameter d3 of the mixing-fast reaction section 3, and the outlet diameter of the diffusion-stabilizing reaction section 4 is d4. The expansion ratio of the diffusion-stabilizing reaction section 4 is d4 / d3 = 1-3:1. The fluid velocity decreases as the channel expands, weakening the turbulence intensity and preventing secondary nucleation. This allows the crystal nuclei to grow slowly in a low-shear, uniform concentration field, resulting in precursor particles with uniform size and regular morphology.

[0020] The feeding section 1 includes a central pipe 11, an inner sleeve 12, and an outer sleeve 13. The central pipe 11 is the feeding channel for the circulating slurry. Furthermore, the length L1 of the central pipe 11 is 2-5 times the internal diameter D1 of the central pipe 11, and the inlet diameter d1 of the nozzle 111 is the same as the internal diameter D1 of the central pipe 11.

[0021] Furthermore, the inner sleeve 12 is fitted outside the central tube 11, and the inner sleeve 12 and the central tube 11 form a jacket 121, which serves as the feed channel for the metal salt and ammonia. Furthermore, the length L2 of the inner sleeve 12 is 2-5 times the inner diameter D2 of the inner sleeve 12, and the gap width δ1 between the inner sleeve 12 and the central tube 11 is 3mm-15mm. The smaller the gap width δ1, the higher the linear velocity and the stronger the shear force. This design enhances the instantaneous mixing capability with the central slurry.

[0022] Furthermore, the outer sleeve 13 is fitted outside the inner sleeve 12, and the outer sleeve 13 and the inner sleeve 12 form an annular channel 122, which serves as the feed channel for the alkali solution. Furthermore, the length L3 of the outer sleeve 13 is 1-3 times the inner diameter D3 of the outer sleeve 13, and the gap width δ2 between the outer sleeve 13 and the inner sleeve 12 is 2mm-10mm. The staged feeding through the sleeves allows the reactants to contact each other gradually from the inside out, avoiding direct contact between the metal salt and a large amount of alkali, which could lead to instantaneous local supersaturation, causing excessively rapid crystal growth or the formation of coarse particles. The length ratio design of the central tube 11, the inner sleeve 12, and the outer sleeve 13 ensures a more stable velocity and pressure field for the three fluids before they enter the mixing zone.

[0023] Furthermore, the central tube 11 has an integrally formed nozzle 111 at its end. The nozzle 111 is conical, and the outlet of the nozzle 111 smoothly transitions to the straight section 112. The diameter of the transition circle is 1 / 6 to 1 / 2 times the outlet diameter d2 of the nozzle 111. The design of the transition circle makes the fluid streamline smooth, without separation, and with a stable peak velocity.

[0024] Furthermore, the outlet of nozzle 111 is located in the contraction section 2, and the outlet of nozzle 111 has a straight section 112 with a length of 1mm-5mm. This design ensures that the accelerated fluid is ejected at a uniform velocity and reduces the change in the outlet streamline angle. Furthermore, the distance between the outlet of nozzle 111 and the inlet of the rapid mixing reaction section 3 is 1-3 times the inlet diameter d1 of nozzle 111. It should be noted that the straight section 112 is located inside nozzle 111 to shape the velocity distribution before fluid ejection; the axial distance between the outlet section of nozzle 111 and the inlet of the rapid mixing reaction section 3 provides free entrainment and premixing space for the high-speed jet after straightening, both ensuring that the reactant fluid enters the rapid mixing reaction section with a uniform and stable flow pattern. Preferably, the cone angle α of nozzle 111 is 30°-45°, and the angles of the inner sleeve 12 and the outer sleeve 13 are consistent. The cone angle design of nozzle 111 ensures the stability, high speed, and non-separation of the jet, providing a stable basis for the Venturi effect.

[0025] Preferably, spiral swirling blades are evenly distributed on the inner wall of the jacket 121, and the spiral swirling blades are welded to the central tube 11. This design allows the outer layer of feed entering the jacket 121 to form a controlled swirling flow, improving the stability of entrainment and creating uniform feeding conditions for the high-speed jet near the nozzle 111.

[0026] Please refer to further information. Figure 3The workflow of the staged mixing reaction system in this embodiment is as follows: sulfate solution, ammonia water, and alkali solution enter the staged mixing co-precipitation reactor at the top for rapid mixing, and then flow into the reaction transfer tank, where the main reaction and maturation zones are formed. The material at the bottom of the reaction transfer tank is divided into three streams. One part is pumped out by the internal circulation pump and returned to the mixer as a high-speed power flow to participate in mixing again. Another part is circulated inside the tank by the external circulation pump to maintain stable concentration and temperature. The product stream that meets the reaction requirements is stably transported from the bottom to the downstream device by the transfer pump, thus forming a continuous closed loop for the entire system. Example 2

[0027] Please continue reading. Figure 1-3 This embodiment provides a staged mixing reactor for NCM811 precursors. Unlike Embodiment 1, the parameters of this embodiment are as follows: The internal diameter D1 of the central tube 11 is 80 mm, and the length L1 is 500 mm. The cone angle of the nozzle 111 is 15°, and the outlet diameter of the nozzle 111 is 13 mm. The tolerances due to manufacturing process limitations in this application are between -0.05 mm and +0.05 mm, and the concentricity is ≤0.05 mm. The staged mixing reactor is made of 95% alumina ceramic, and the inner wall roughness of the central tube is Ra=0.4 μm.

[0028] Furthermore, the inner diameter D2 of the inner sleeve 12 is set to 100mm, and the gap δ1 between the inner sleeve 12 and the central tube 11 is 10mm. There are 12 spiral swirl blades, each with a thickness of 5mm and a lead of 12mm, with installation tolerances limited to within 0.1mm; concentricity is limited to within 0.1mm; the inner wall roughness of the inner sleeve 12 is Ra=0.8μm; and the inner sleeve 12 is made of TA4 high-purity titanium.

[0029] Furthermore, the inner diameter of the outer sleeve 13 is set to 110mm, and the gap between the outer sleeve 13 and the inner sleeve is set to 5mm; the manufacturing process is controlled to limit the concentricity to within 0.1mm, and the inner wall roughness Ra of the outer sleeve 13 is set to 0.8μm; the material of the outer sleeve 13 is TA4 high-purity titanium.

[0030] Furthermore, the throat diameter of the contraction section 2 is designed to be 65 mm, and the effective throat length is 35 mm. To ensure stable axial flow of the slurry jet within this section, the straightness of the contraction section is controlled within 0.02 mm / m to avoid jet deviation or local eddies. The surface roughness Ra of the inner surface of the contraction section 2 is limited to 0.8 μm to reduce wall friction resistance. The internal diameter d3 of the mixing fast reaction section 3 is set to 65 mm, and the length is set to 850 mm. The manufacturing process tolerance is limited to between -0.1 mm and +0.1 mm, and the coaxiality with the throat is limited to within 0.1 mm. The material of the mixing fast reaction section 3 is 95% alumina ceramic.

[0031] Furthermore, the inlet diameter of the diffusion stabilization reaction section 4 is the same as the internal diameter d3 of the mixing rapid reaction section 3, which is 65 mm. The outlet diameter d4 of the diffusion stabilization reaction section 4 is set to 100 mm, and the length is set to 550 mm. Even further, the expansion angle of the diffusion stabilization reaction section 4 is 7°, and the manufacturing process tolerance is limited to between -1° and +1°. The diffusion stabilization reaction section 4 is made of high-purity TA4 titanium.

[0032] During operation, circulating slurry is introduced into the central tube 11, salt-ammonia premix is ​​introduced into the inner sleeve 12, and alkali solution is introduced into the outer sleeve 13. These three feed streams are mixed and reacted in a graded sequence within the device. The circulating slurry is accelerated within the ceramic central tube 11, and after reaching the integrally formed nozzle 111 at the end, its speed rapidly increases after entering the 15° cone-angle acceleration section. The salt-ammonia premix is ​​forced into a spiral trajectory upon entering the jacket 121, generating a stable swirling flow and ensuring thorough homogenization before the salt-ammonia complex reaches the nozzle 111. The design of the outer sleeve 13 ensures that the alkali solution enters near the contraction section 2 as a uniform thin film. The contraction section 2 constitutes a stable Venturi low-pressure zone. When the high-speed jet from the center enters the contraction section 2, a continuous pressure drop is formed, strongly entraining the outer premix and alkali solution. The three feed streams rapidly reach a uniform concentration state in the region between the nozzle 111 outlet and the rapid mixing reaction section 3. Primary crystal nuclei are continuously and uniformly generated within the rapid mixing reaction section 3, resulting in regular grain morphology. The diffusion stabilization reaction stage 4 gradually reduces the fluid velocity, weakens shear, and further refines the particle morphology.

[0033] Under the conditions of this embodiment, the feed flow rate of the circulating slurry is 11 m³ / s. 3 / h, the flow rate of the salt-ammonia premix is ​​0.8m³ / h. 3 / h, alkali solution flow rate is 0.3m 3The precursor product obtained through continuous operation, after particle size analysis, showed a D50 of 3 μm and a relative standard deviation (RSD) of 2.8%, indicating high particle size concentration. Morphology analysis showed that the particles exhibited a highly spherical structure with a sphericity of 0.97, indicating good surface roundness. Further impurity content testing revealed that Fe, Cr, and Na impurities were all below 0.005 ppm, significantly lower than the industry requirements for NCM811 precursors. This demonstrates that the reactor's internal material selection, flow field control, and mixing uniformity effectively suppressed secondary contamination and localized corrosion precipitation.

[0034] The staged mixing reactor in this embodiment can stably obtain NCM811 precursor products with uniform particle size, high sphericity, and low metal impurities, meeting the stringent requirements for morphology and purity of power battery materials. Example 3

[0035] Please continue reading. Figure 1-3 The difference between this embodiment and embodiment 2 is that: the cone angle of nozzle 111 is adjusted to 12°, the outlet diameter of nozzle 111 is reduced to 10mm, the throat diameter of contraction section 2 is 60mm, the diameter of mixing rapid reaction section 3 is 60mm, and the length of mixing rapid reaction section 3 is increased to 1150mm; the outlet diameter d4 of diffusion stabilization reaction section 4 is increased to 110mm, and the length of diffusion stabilization reaction section 4 is 650mm.

[0036] Under the same raw material ratio and feeding mode as in Example 2, the three feed streams achieved a higher initial jet velocity in the nozzle 111 with a smaller cone angle. Due to the finer outlet and narrower throat of the nozzle 111, the length of the fast reaction mixing section 3 is increased, the Venturi pressure drop is further increased, and the outer premixed liquid and alkali liquid are more strongly entrained when entering the contraction section, thereby forming a high-speed turbulent mixing zone before the inlet of the fast reaction section.

[0037] The product obtained under the above structural conditions was tested and found to have a particle size D50 of 3.5 μm and a relative standard deviation (RSD) of 4.2%, indicating that the particle distribution is slightly wider than in Example 2, but still maintains a relatively stable particle size range. The particle sphericity reached 0.96, which is basically the same as in Example 2, and the particle morphology remains good. Under the same raw materials, temperature, pH, total metal concentration, and residence time, the NCM811 precursor prepared using a conventional mechanically stirred reactor had a particle size distribution RSD of 7.5% and a sphericity of 0.91. Therefore, the staged mixing reactor of this embodiment has significant advantages over the conventional mechanically stirred reactor in preparing NCM811 precursors. It not only maintains a more stable and narrower particle size range, improving particle size uniformity, but also ensures high particle sphericity, resulting in better particle morphology. This advantage is crucial for meeting the stringent requirements of power battery materials for precursors, as precursors with uniform particle size and high sphericity help improve battery performance and stability.

[0038] Further testing revealed that the levels of metallic impurities such as Fe, Cr, and Na were all below 0.01 ppm, meeting the purity requirements for NCA precursors. Therefore, Example 3 showed higher sphericity, lower impurity content, and superior overall morphology and purity compared to Example 2.

[0039] The working principle of this invention is as follows: This application achieves a controlled co-precipitation reaction of metal salts, ammonia, and alkali solutions through coupled fluid behaviors such as central jet, Venturi negative pressure entrainment, swirling premixing, and axial turbulent mixing. During operation, the circulating slurry first enters the contraction section 2 from the central pipe 11 in the form of a high-speed jet. Since the diameter of the contraction section 2 is significantly smaller than that of the outlet of the central pipe 11, the slurry jet accelerates sharply when passing through the throat, forming a local negative pressure zone of -0.02 to -0.03 MPa. This negative pressure exerts a stable entrainment effect on the surrounding channels.

[0040] Under negative pressure, the metal salt solution and ammonia water, premixed by the spiral swirling blades inside the jacket 121, are continuously drawn into the throat region; the alkaline solution is synchronously drawn in under the same negative pressure. Because the two outer liquids undergo swirling premixing before reaching the throat, their flow velocity direction is consistent with the central jet, thus avoiding collision and stagnation, allowing the three fluids to quickly merge into the central jet at the throat to form a complete mixed stream.

[0041] The mixed stream forms a highly turbulent region in the throat and subsequent rapid reaction section 3, generating high shear force and a strong volumetric entrainment effect, which enables the metal ion complex solution and the alkaline solution to quickly and uniformly mix. At this point, the local concentration distribution of the system is uniform, which can effectively avoid coarse crystal nucleation caused by instantaneous supersaturation, and achieve stable and controllable crystal nucleation and initial particle formation.

[0042] Subsequently, the mixed slurry enters the diffusion stabilization reaction section 4, where the flow field gradually transitions from a highly turbulent region to a weakly turbulent stable region, resulting in reduced flow velocity and shear force. Within this section, the particles experience a relatively mild growth environment, achieving secondary growth and morphological rounding under uniform flow conditions, ultimately yielding co-precipitated precursor particles with narrow particle size distribution and high sphericity. The mature slurry is continuously discharged from the outlet of diffusion stabilization reaction section 4 to the downstream buffer tank, where necessary ripening, aging, and solid-liquid separation processes are performed, providing a stable and consistent intermediate product for the preparation of NCM or NCA precursors.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A staged mixing co-precipitation reactor based on the Venturi effect, characterized in that, It includes a feeding section (1) and a contraction section (2), a mixing rapid reaction section (3) and a diffusion stabilization reaction section (4) that are connected sequentially downstream of the feeding section (1). The feeding section (1) includes a central tube (11), an inner sleeve (12) and an outer sleeve (13). The central tube (11) is the feeding channel for circulating slurry. The inner sleeve (12) is sleeved outside the central tube (11), and the inner sleeve (12) and the central tube (11) form a jacket (121). The jacket (121) is the feeding channel for metal salt and ammonia. The outer sleeve (13) is sleeved outside the inner sleeve (12), and the outer sleeve (13) and the inner sleeve (12) form an annular channel (122). The annular channel (122) is the feeding channel for alkali solution. The end of the central tube (11) has an integrally formed nozzle (111). The nozzle (111) is conical, and the outlet of the nozzle (111) has a straight section (112).

2. The Venturi effect based fractional mixed co-precipitation reactor according to claim 1, characterized in that, The outlet of the nozzle (111) is located at a cone angle of 10° to 25° in the contraction section (2), and the distance between the outlet of the nozzle (111) and the inlet of the mixing rapid reaction section (3) is 1 to 3 times the inlet diameter d1 of the nozzle (111).

3. The staged mixing co-precipitation reactor based on the Venturi effect according to claim 1, characterized in that, The mixing fast reaction section (3) is a cylindrical channel. The mixing fast reaction section (3) is used to realize the forced mixing of fluid and the homogeneous generation of crystal nuclei. The length-to-diameter ratio of the length L3 of the mixing fast reaction section (3) to the internal diameter d3 of the mixing fast reaction section (3) is L3 / d3=5:1~15:

1.

4. The staged mixing co-precipitation reactor based on the Venturi effect according to claim 1, characterized in that, The diffusion stabilization reaction section (4) is a channel that expands in the downstream direction. The inlet diameter of the diffusion stabilization reaction section (4) is the same as the internal diameter d3 of the mixing rapid reaction section (3). The outlet diameter of the diffusion stabilization reaction section (4) is d4. The expansion ratio of the diffusion stabilization reaction section (4) is d4 / d3=2-3:

1.

5. The staged mixing co-precipitation reactor based on the Venturi effect according to claim 1, characterized in that, The length L1 of the central tube (11) is 2-5 times the inner diameter D1 of the central tube (11), and the inlet diameter d1 of the nozzle (111) is the same as the inner diameter D1 of the central tube (11).

6. The staged mixing co-precipitation reactor based on the Venturi effect according to claim 1, characterized in that, The length L2 of the inner sleeve (12) is 2-5 times the inner diameter D2 of the inner sleeve (12), and the gap width δ1 between the inner sleeve (12) and the central tube (11) is 3mm to 15mm.

7. The staged mixing co-precipitation reactor based on the Venturi effect according to claim 1, characterized in that, The length L3 of the outer sleeve (13) is 1-3 times the inner diameter D3 of the outer sleeve (13), and the gap width δ2 between the outer sleeve (13) and the inner sleeve (12) is 2mm to 10mm.

8. The staged mixing co-precipitation reactor based on the Venturi effect according to claim 1, characterized in that, The length of the straight section (112) is 1mm to 5mm, which can effectively improve the stability of the flow field, reduce eddy and turbulent phenomena, reduce pressure loss, and make the slurry flow more stable; the outlet of the nozzle (111) and the straight section (112) are smoothly transitioned, and the diameter of the transition circle is 1 / 6 to 1 / 2 times the outlet diameter d2 of the nozzle (111).

9. The staged mixing co-precipitation reactor based on the Venturi effect according to claim 1, characterized in that, The cone angle α of the nozzle (111) is 30° to 45°, and the inner sleeve (12) and the outer sleeve (13) have the same angle.

10. The staged mixing co-precipitation reactor based on the Venturi effect according to claim 1, characterized in that, The inner wall of the jacket (121) is uniformly distributed with spiral swirling blades, which are welded to the central tube (11).

Images