ROTATING LIQUID FILM REACTOR WITH GAS-LIQUID CONCURRENT AND USE THEREOF IN PREPARATION OF METAL HYDROXIDES

Abstract

The present disclosure relates to a rotating liquid film reactor with gas-liquid concurrent and use thereof in preparation of metal hydroxides. The present disclosure starts from the basic process of preparing metal hydroxides by a gas-liquid precipitation method, and designs a rotating liquid film reactor with gas-liquid multi-fluid concurrent through computational fluid dynamics simulation analysis. Multiple gas-liquid fluid inlets are constructed, and the traditional vertical inlet is improved to tangential feed along the rotation direction, which enhances the forced mixing process of gas and liquid phases in the reaction space, and intensifies the micro-mixing and nucleation process of reactant ions. An inlet anti overflow device is further provided to prevent fluid from overflowing upwardly upon increasing the inlet flow volume, thereby improving product quality control and achieving effective control of particle size and distribution in nucleation while improving production efficiency and quality, obtaining products with smaller particle size and narrower distribution. The particle size of the product is controlled within the range of 15-200 nm, while the primary particle size distribution range is reduced to 30-60 nm.

Claims

1. A rotating liquid film reactor with gas-liquid multi-fluid concurrent, wherein the reactor comprises a closed casing as a stator, the stator has an upper end that is closed; a rotatable conical rotor is provided in the stator, a motor is connected with the rotor from below; a reactor body is composed of the stator and the rotor that is rotatable freely and connected to the motor; a plurality of liquid feed ports are symmetrically arranged on both left and right sides of the stator, a liquid is fed in a direction tangential to a direction of rotation of the rotor, the liquid feed ports are located between the stator and the rotor, and a lower end of the liquid feed ports is lower than an upper edge of the rotor and located in an upper half portion of the rotor; a gas feed port is constructed at a central position of the stator, gas is introduced into the upper half portion of the rotor; a gas disperser is provided in the rotor; a reaction liquid is injected through the liquid feed port, either from the same side or opposite sides, to a level of to of a height of the inlet in the rotor; a gas is injected through the gas feed port and uniformly outflows through the gas disperser, a height of a gas outlet is lower than that of a liquid outlet; a discharge port is provided at a lower end of the stator.

2. The rotating liquid film reactor with gas-liquid multi-fluid concurrent according to claim 1, wherein the feed port is provided in four arranged in a cross pattern, in six uniformly distributed at an angle of 60, or in eight uniformly distributed at an angle of 45.

3. The rotating liquid film reactor with gas-liquid multi-fluid concurrent according to claim 1, wherein an anti overflow device is further provided by providing two circular hole-type adjusting bolts on opposite sides horizontally above the stator, with a height of 10-20 cm, which are connected with the rotor inside.

4. The rotating liquid film reactor with gas-liquid multi-fluid concurrent according to claim 1, wherein an inner wall of the stator and a surface of the rotor are engraved with threads in a direction at 10 to 170.

5. The rotating liquid film reactor with gas-liquid multi-fluid concurrent according to claim 1, wherein a stator-rotor clearance is 0.1-0.5 mm, and a rotor height is 5-25 cm.

6. The rotating liquid film reactor with gas-liquid multi-fluid concurrent according to claim 1, wherein an inclination angle of the rotor which is an angle between an inclined edge and a bottom edge of the rotor in the vertical direction is in the range of 36 to 86.

7. The rotating liquid film reactor with gas-liquid multi-fluid concurrent according to claim 1, wherein a bore diameter of the disperser is 1-3 mm.

8. The rotating liquid film reactor with gas-liquid multi-fluid concurrent according to claim 1, wherein a rotor speed is in a range of 50 to 8000 rpm, and a fluid mixing flow rate in the reactor is 7 to 150 m/s.

9. Use of the rotating liquid film reactor with gas-liquid multi-fluid concurrent according to claim 1 in preparation of metal hydroxides.

10. The use according to claim 9, wherein the metal hydroxides are magnesium hydroxide, aluminum hydroxide, or lanthanum hydroxide, comprising introducing an ammonia gas through a gas feed port, introducing a magnesium salt solution, an aluminum salt solution, or a lanthanide salt solution through a liquid feed port.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a schematic diagram of the front structure of a rotating liquid film reactor with gas-liquid multi-fluid concurrent of the present disclosure. Reference numerals: 1gas feed port, 2liquid feed port, 3anti overflow device, 4stator casing, 5rotor, 6outlet, 7motor, 8adjusting bolt in slot, 9stator, 10base.

[0019] FIG. 2 shows the top views of 4, 6, and 8 liquid feed ports, respectively.

[0020] FIG. 3 is the XRD pattern of the layered magnesium hydroxide in Example 1.

[0021] FIG. 4 is an SEM image of the layered aluminum hydroxide in Example 1.

[0022] FIG. 5 shows the laser particle size distribution of lanthanum hydroxide obtained from Example 2.

DETAILED DESCRIPTION

Example 1

[0023] A rotating liquid film reactor with gas-liquid multi-fluid concurrent in FIG. 1 comprises a closed casing as a stator, the stator has an upper end that is closed; a rotatable conical rotor is provided in the stator, a motor is connected with the rotor from below; a reactor body is composed of the stator and the rotor that is rotatable freely and connected to the motor. The stator-rotor clearance is 0.1-0.5 mm. The inner wall of the stator and the surface of the rotor are engraved with threads in a direction at 80. The rotor height is 8 cm, and the inclination angle of the rotor is 72. An anti overflow device is further provided by providing a circular hole-type adjusting bolt on a horizontal plane above the stator, with a height of 10 cm, configured to be connected with the rotor inside. Four liquid feed ports arranged in a cross pattern are provided symmetrically on both left and right sides of the stator. The liquid feed ports are located between the stator and the rotor, and the lower end of the liquid feed ports is lower than the upper edge of the rotor. The reaction liquid is injected in a direction tangential to a direction of rotation of the rotor. The gas feed ports are located in the upper middle part of the rotor, and the gas flows out through a gas disperser with a bore diameter of 1 mm. The inclination angle of the rotor is an angle between an inclined edge and a bottom edge of the rotor in the vertical direction.

[0024] Specific operations in the use of the rotating liquid film reactor with gas-liquid multi-fluid concurrent in the preparation of magnesium hydroxide are described below.

[0025] MgCl.sub.2 and NH.sub.3 were injected at a molar ratio NH.sub.3/Mg.sup.2+=2.5:1 in the same feed time, where [Mg.sup.2+]=1.0 mol/L, and the liquids were injected through four liquid feed ports at 0.1 L/min. The flow rate of ammonia gas to be introduced through the gas feed port in a corresponding time was calculated to be 4.48 L/min. The stator-rotor clearance of the reactor was 0.1 mm, and the rotation speed of the rotor was 5000 rpm. The slurry obtained from the reaction was crystallized at 100 C. in a crystallization reactor for 3 h, and the product was obtained after filtration, washing, and drying. The average particle size of the product was 50 nm, with a particle size distribution of 30-70 nm.

[0026] The crystal structure of the product was characterized using XRD6000 X-ray powder diffractometer from Shimadzu. FIG. 3 shows a XRD spectra, from which it can be seen that the characteristic diffraction peaks of Mg(OH).sub.2 appear approximately at 2=4.8, 38.0, 50.8, and 58.7, with sharp peaks and a low and flat baseline, indicating that the product has a complete crystal structure.

[0027] The particle size and the morphology were observed using the Hitachi H-800 transmission electron microscope. FIG. 4 is a scanning electron microscope image, from which it can be seen that the particle size of the product is from 30 to 60 nm.

Example 2

[0028] The rotating liquid film reactor with gas-liquid multi-fluid concurrent in FIG. 1 comprises a closed casing as a stator, the stator has an upper end that is closed; a rotatable conical rotor is provided in the stator, a motor is connected with the rotor from below; a reactor body is composed of the stator and the rotor that is rotatable freely and connected to the motor; the stator-rotor clearance is 0.3 mm. The inner wall of the stator and the surface of the rotor stated are engraved with threads in a direction at 40, the rotor height is 10 cm, and the inclination angle of the rotor is 75. An anti overflow device is further provided by providing a circular hole-type adjusting bolt on a horizontal plane above the stator, with a height of 12 cm, which is connected with the rotor inside. A plurality of liquid feed port is symmetrically arranged on both left and right sides of the stator. Six liquid feed ports are constructed to be uniformly distributed. The liquid feed ports are located between the stator and the rotor, and the lower end of the feed ports is lower than the upper edge of the rotor. The reaction liquid is injected in a direction tangential to a direction of rotation of the rotor. The gas feed ports are located in the upper middle part of the rotor, and the gas flows out through a gas disperser with a bore diameter of 2 mm. The inclination angle of the rotor is an angle between an inclined edge and a bottom edge of the rotor in the vertical direction.

[0029] Specific operations in the use of the rotating liquid film reactor with gas-liquid multi-fluid concurrent in the preparation of aluminum hydroxide are described below.

[0030] AlCl.sub.3 and NH.sub.3 were injected at a molar ratio NH.sub.3/Al.sup.3+=4:1 in the same feed time, where [Al.sup.3+]=1.0 mol/L, the liquids were injected through six liquid feed ports at 0.1 L/min. The flow rate of ammonia gas to be introduced through the gas feed port in a corresponding time was calculated to be 8.96 L/min. The rotation speed of the rotor was 4000 rpm. The slurry obtained from the reaction was crystallized at 60 C. in a crystallization reactor for 6 h, and the Al(OH).sub.3 product was obtained after filtration, washing, and drying. The average particle size of the product was 90 nm, with a particle size distribution of 60-160 nm.

[0031] The particle size of the sample was measured by Malvern mastersizer 2000 laser particle size analyzer. FIG. 5 illustrates the laser particle size distribution, from which it can be seen that the average particle size of the product is 96 nm and d.sub.90=152 nm.

Example 3

[0032] The rotating liquid film reactor with gas-liquid multi-fluid concurrent in FIG. 1 comprises a closed casing as a stator, the stator has an upper end that is closed; a rotatable conical rotor is provided in the stator, a motor is connected with the rotor from below; a reactor body is composed of the stator and the rotor that is rotatable freely and connected to the motor; the stator-rotor clearance is 0.2 mm. The inner wall of the stator and the surface of the rotor stated are engraved with threads in a direction at 60, the rotor height is 12 cm, and the inclination angle of the rotor is 70. An anti overflow device is further provided by providing a circular hole-type adjusting bolt on a horizontal plane above the stator, with a height of 15 cm, which is connected with the rotor inside. A plurality of liquid feed port is symmetrically arranged on both left and right sides of the stator. Eight liquid feed ports are constructed to be uniformly distributed. The liquid feed ports are located between the stator and the rotor, and the lower end of the feed ports is lower than the upper edge of the rotor. The reaction liquid is injected in a direction tangential to a direction of rotation of the rotor. The gas feed ports are located in the upper middle part of the rotor, and the gas flows out through a gas disperser with a bore diameter of 3 mm. The inclination angle of the rotor is an angle between an inclined edge and a bottom edge of the rotor in the vertical direction.

[0033] Specific operations in the use of the rotating liquid film reactor with gas-liquid multi-fluid concurrent in the preparation of lanthanum hydroxide are described below.

[0034] LaCl.sub.3 and an ammonia gas were injected at a molar ratio NH.sub.3/La.sup.3+=5:1 in the same feed time, where [La.sup.3+]=1.0 mol/L, the liquids were injected through eight liquid feed ports at 0.1 L/min. The flow rate of ammonia gas to be introduced through the gas feed port in a corresponding time was calculated to be 11.2 L/min. The rotation speed of the rotor was 3000 rpm. The slurry obtained from the reaction was crystallized at 120 C. in a crystallization reactor for 1 h, and the La (OH) 3 product was obtained after filtration, washing, and drying. The average particle size of the product was 100 nm, with a particle size distribution of 80-140 nm.