Continuous preparation method of rare earth compound precipitate

Abstract

The invention relates to the field of continuous preparation of rare earth compound precipitates, and discloses a continuous preparation method of rare earth compound precipitates, which comprises the following steps: dilution and activation: adding fine crystal mush, rare earth feed liquid and recycled precipitation wastewater into an activation configuration tank through a flow controller, and stirring to obtain a mixed solution; crystal nucleus growth: overflowing into a growth precipitation tank through the mixed solution, then adding an ammonium bicarbonate solution, and performing stirring treatment to obtain crystal nucleus growth slurry; and complete crystallization: enabling the crystal nucleus growth slurry to overflow into a crystallization precipitation tank, then adding the ammonium bicarbonate solution again, and carrying out stirring treatment. The whole continuous precipitation process is divided into the steps of dilution activation, crystal nucleus growth, complete crystallization, standing aging, graded discharging and the like, stage-by-stage overflow is carried out, segmented continuous control is achieved, different reaction stages are controlled in respective single reaction tanks, precise control is achieved through stage-by-stage overflow and segmentation, and the whole reaction process is continuous and controllable.

Description

Technical Field

[0001] The invention relates to the technical field of continuous precipitation preparation of rare earth compounds, in particular to a continuous precipitation preparation method of rare earth compounds. Background Art

[0002] Rare earth metals have extremely important uses and are an important component of contemporary high-tech new materials. A series of compound semiconductors, electronic optical materials, special alloys, new functional materials and organic metal compounds composed of rare earth metals and non-ferrous metals all require the use of rare earth metals with unique properties; although the amount used is not large, it is crucial and indispensable; therefore, it is widely used in contemporary communication technology, electronic computers, aerospace development, medicine and health, photosensitive materials, optoelectronic materials, energy materials and catalyst materials, etc. China is rich in rare earth metal minerals, which provides good resource conditions for the development of the rare earth metal industry.

[0003] The traditional rare earth precipitation process is an intermittent reaction in a single reactor, which cannot be carried out continuously. This preparation method not only makes the operation cumbersome, the labor rate is low, but also the energy consumption is high. Since it relies on the manual intermittent production operation of the operator, the consistency of the produced products is poor, and the crystal form, particle size and distribution of the rare earth also fluctuate greatly. Based on this, it is necessary to propose a continuous preparation method for rare earth compound precipitation to solve the above problems. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for continuous preparation of rare earth compounds by precipitation, which solves the problem that the traditional rare earth precipitation process is an intermittent reaction in a single reactor and cannot be carried out continuously.

[0005] To achieve the above objectives, the present invention is implemented by the following technical scheme: A method for continuous preparation of rare earth compounds by precipitation, comprising the following steps:

[0006] S1. Dilution and activation: adding fine crystal slurry, rare earth liquid and recycled sedimentation wastewater into the activation configuration tank through a flow controller, and then stirring to obtain a mixed solution;

[0007] S2, crystal nucleus growth: the mixed solution overflows into the growth precipitation tank, and then the ammonium carbonate solution is added and stirred to obtain a crystal nucleus growth slurry;

[0008] S3, complete crystallization: the crystal nucleus growth slurry overflows into the crystallization precipitation tank, and then the ammonium carbonate solution is added again and stirred to obtain a completely crystallized slurry;

[0009] S4, static aging: the completely crystallized slurry overflows into an aging sedimentation tank, a precipitant is added and stirred, thereby obtaining a crystallized rare earth carbonate slurry;

[0010] S5. Gradual unloading: The crystallized rare earth carbonate slurry overflows into the graded unloading tank, and the fine crystals in the crystallized rare earth carbonate slurry are drained to the crystal slurry transfer tank through the rare earth liquid, and are transported back to the activation configuration tank by a pump; the remaining crystallized rare earth carbonate slurry is transported to the slurry transfer tank through the unloading port, and then transported to the vacuum belt filter by a pump for filtration, so as to obtain large-particle rare earth carbonate.

[0011] Preferably, the fine crystal slurry in step S1 includes the fine crystal grains in step S5, and the stirring process includes a stirring speed of 50-120 r / min and a reaction temperature of 40°C-80°C.

[0012] Preferably, the stirring treatment in step S2 includes a stirring speed of 50-120 r / min, a reaction temperature of 40° C.-80° C., a slurry pH of 4.8-5.5, and a reaction time of 0.5-1 hour.

[0013] Preferably, the stirring treatment in step S3 includes a stirring speed of 50-120 r / min, a reaction temperature of 40°C-80°C, a slurry pH of 6.4-6.8, a reaction time of 0.5-1 hour, and a rare earth content in the supernatant of the completely crystallized slurry is less than 0.07 g / L.

[0014] Preferably, the stirring treatment in step S4 includes a stirring speed of 20-40 r / min, a reaction temperature of 40°C-80°C, a slurry pH of 6.4-6.8, an aging time of 0.5-1 hour, and the precipitant is a mixture of one or more of ammonium bicarbonate and ammonia water, with a concentration of 0.5-1.5 mol / L.

[0015] Preferably, the amount of fine crystal slurry added in step S1 is 15%-25% of the amount of rare earth aging tank, the concentration of rare earth ions in the rare earth feed liquid is 1.2-1.8 mol / L, and the concentration of rare earth ions in the mixed liquid is 0.2-0.8 mol / L.

[0016] Preferably, the activation configuration tank, growth sedimentation tank, crystallization sedimentation tank, and aging sedimentation tank are each provided with a pH meter, and one side of the growth sedimentation tank and the crystallization sedimentation tank are each provided with a carbon ammonium flow meter, and the carbon ammonium flow meter on one side of the growth sedimentation tank and the crystallization sedimentation tank is connected to the pH meter inside the growth sedimentation tank and the crystallization sedimentation tank.

[0017] Preferably, the grading unloading trough includes a grading zone and a discharge zone, the particle size corresponding to the sedimentation rate in the grading zone is larger than the particle size of 80% of the mass fraction in the crystallized rare earth carbonate slurry, the grading zone includes a slurry transfer trough, and the discharge zone includes a slurry transfer trough.

[0018] The present invention provides a method for continuous preparation of rare earth compounds by precipitation. It has the following beneficial effects:

[0019] 1. The present invention divides the entire continuous precipitation process into the steps of dilution activation, crystal nucleus growth, complete crystallization, static aging and graded unloading, and overflows step by step to achieve segmented continuous control. In the whole process, a single-stage precipitation tank is decomposed into several smaller-volume series-connected reaction tanks, and the carbon precipitation reaction process is distinguished. Different reaction stages are controlled in their respective single reaction tanks. Through step-by-step overflow and segmented precise control, the entire reaction process is continuously controllable, thereby solving the problem that the traditional rare earth precipitation process is an intermittent reaction in a single reactor and cannot be carried out continuously.

[0020] 2. The present invention discharges the obtained precipitated crystal slurry in a graded manner, i.e., part of the fine crystal precipitate is pumped into a configuration tank to be used as a seed crystal, and the other part is dried by centrifugal filtration to obtain rare earth carbonate; thereby, the crystal form of the rare earth carbonate precipitate is controlled as a whole, so that the obtained rare earth carbonate product has large particles, high specific gravity, good operation continuity, and high labor productivity. Moreover, because of the continuous production, the reaction has extremely strong continuity, so that the produced product has high consistency.

[0021] 3. In the production process of the present invention, as the rare earth solution and the precipitant are continuously injected, the rare earth compound precipitate formed at the same time can be automatically and continuously discharged, thereby realizing continuous production and providing convenience for subsequent production processes. The produced rare earth compound products have fine crystals, high particle size concentration, and few non-rare earth impurities. The process of the present invention is simple and reasonable, the device structure is simple, the operation is convenient, and it is easy to maintain and repair. It requires little investment and has good effects, which is beneficial for enterprises to reduce production costs and increase profits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention provides a method flow chart for the continuous preparation of rare earth compounds by precipitation. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example:

[0025] Please see attached Figure 1 The embodiment of the present invention provides a method for continuous preparation of rare earth compounds by precipitation, comprising the following steps:

[0026] S1. Dilution and activation: adding fine crystal slurry, rare earth liquid and recycled sedimentation wastewater into the activation configuration tank through a flow controller, and then stirring to obtain a mixed solution;

[0027] S2, crystal nucleus growth: the mixed solution overflows into the growth precipitation tank, and then the ammonium carbonate solution is added and stirred to obtain a crystal nucleus growth slurry;

[0028] S3, complete crystallization: the crystal nucleus growth slurry overflows into the crystallization precipitation tank, and then the ammonium carbonate solution is added again and stirred to obtain a completely crystallized slurry;

[0029] S4, static aging: the completely crystallized slurry overflows into an aging sedimentation tank, a precipitant is added and stirred, thereby obtaining a crystallized rare earth carbonate slurry;

[0030] S5. Gradual unloading: The crystallized rare earth carbonate slurry overflows into the graded unloading tank, and the fine crystals in the crystallized rare earth carbonate slurry are drained to the crystal slurry transfer tank through the rare earth liquid, and are transported back to the activation configuration tank by a pump; the remaining crystallized rare earth carbonate slurry is transported to the slurry transfer tank through the unloading port, and then transported to the vacuum belt filter by a pump for filtration, so as to obtain large-particle rare earth carbonate.

[0031] Specifically, fine crystal slurry, rare earth liquid and recycled precipitation wastewater are added to the activation configuration tank through a flow controller, and then stirred to obtain a mixed solution, thereby achieving the purpose of diluting the rare earth liquid concentration and activating the seed crystals; the mixed solution overflows into the growth precipitation tank, and then the ammonium carbonate solution is added and stirred to obtain a crystal nucleus growth slurry, so that the crystal nuclei are fully generated and grown; the crystal nucleus growth slurry overflows into the crystallization precipitation tank, and then the ammonium carbonate solution is added again and stirred to obtain a completely crystallized slurry, thereby ensuring complete precipitation and making the rare earth content in the supernatant of the completely crystallized slurry less than 0.07g / L; the completely crystallized slurry overflows into the aging precipitation tank, a precipitant is added and stirred to obtain a crystallized rare earth carbonate slurry, thereby crystallizing the rare earth carbonate; the crystallized rare earth carbonate slurry overflows into the grading discharge tank, and the rare earth The liquid drains the fine crystals in the crystallized rare earth carbonate slurry to the crystal slurry transfer tank, and is transported back to the activation configuration tank by a pump; the remaining crystallized rare earth carbonate slurry is transported to the slurry transfer tank through the discharge port, and then transported to the vacuum belt filter by a pump for filtration, so as to obtain large-particle rare earth carbonate, thereby completing the continuous preparation of rare earth compound precipitation, and the whole continuous precipitation process is divided into the steps of dilution activation, crystal nucleus growth, complete crystallization, static aging and graded unloading, and overflows step by step to achieve segmented continuous control, and the whole process decomposes the single-stage precipitation tank into several smaller-volume series-connected reaction tanks, distinguishes the carbon precipitation reaction process, and controls different reaction stages in their respective single reaction tanks. Through step-by-step overflow and segmented precision control, the whole reaction process is continuously controllable, thereby solving the problem that the traditional rare earth precipitation process is an intermittent reaction in a single reactor and cannot be carried out continuously.

[0032] The fine crystal slurry in step S1 includes the fine crystal grains in step S5, and the stirring treatment includes a stirring speed of 50-120r / min and a reaction temperature of 40°C-80°C; the amount of the fine crystal slurry added in step S1 is 15%-25% of the amount of rare earth aging tank, the concentration of rare earth ions in the rare earth feed liquid is 1.2-1.8 mol / L, and the concentration of rare earth ions in the mixed liquid is 0.2-0.8 mol / L.

[0033] Specifically, by controlling the stirring speed to 50-120r / min, the reaction temperature to 40°C-80°C, the addition amount of fine crystal slurry to 15%-25% of the rare earth aging amount, and the concentration of rare earth ions in the rare earth solution to 1.2-1.8mol / L, the purpose of diluting the rare earth solution concentration and activating the seed crystals is achieved.

[0034] The stirring treatment in step S2 includes a stirring speed of 50-120 r / min, a reaction temperature of 40° C.-80° C., a slurry pH of 4.8-5.5, and a reaction time of 0.5-1 hour.

[0035] Specifically, the stirring speed is controlled to 50-120 r / min, the reaction temperature is controlled to 40° C.-80° C., the pH value of the slurry is controlled to 4.8-5.5, and the reaction time is controlled to 0.5-1 hour, so that the crystal nuclei are fully generated and grown.

[0036] The stirring treatment in step S3 includes a stirring speed of 50-120 r / min, a reaction temperature of 40°C-80°C, a slurry pH of 6.4-6.8, a reaction time of 0.5-1 hour, and a rare earth content in the supernatant of the completely crystallized slurry is less than 0.07 g / L.

[0037] Specifically, by controlling the stirring speed to 50-120 r / min, the reaction temperature to 40°C-80°C, the slurry pH to 6.4-6.8, and the reaction time to 0.5-1 hour, the rare earth content in the supernatant of the completely crystallized slurry is lower than 0.07 g / L, ensuring complete precipitation.

[0038] The stirring treatment in step S4 includes a stirring speed of 20-40 r / min, a reaction temperature of 40°C-80°C, a slurry pH of 6.4-6.8, an aging time of 0.5-1 hour, and a precipitant of one or more of ammonium bicarbonate and ammonia water, with a concentration of 0.5-1.5 mol / L.

[0039] Specifically, the rare earth carbonate is crystallized by controlling the stirring speed to 20-40 r / min, the reaction temperature to 40°C-80°C, the slurry pH to 6.4-6.8, the aging time to 0.5-1 hour, and the precipitant to be a mixture of one or more of ammonium bicarbonate and ammonia water at a concentration of 0.5-1.5 mol / L.

[0040] The activation configuration tank, the growth precipitation tank, the crystallization precipitation tank, and the aging precipitation tank are all provided with pH meters, and the growth precipitation tank and the crystallization precipitation tank are both provided with ammonium carbonate flow meters on one side, and the ammonium carbonate flow meters on the growth precipitation tank and the crystallization precipitation tank are connected to the pH meters inside the growth precipitation tank and the crystallization precipitation tank;

[0041] Specifically, the pH meter is used to monitor the pH value of the solution in each tank, and the feeding rate of the ammonium carbonate solution is adjusted according to the pH value of the solution through the ammonium carbonate flowmeter. During the production process, as the rare earth solution and the precipitant are continuously injected, the rare earth compound precipitate formed at the same time can be automatically and continuously discharged, thereby realizing continuous production and providing convenience for subsequent production processes. The produced rare earth compound products have fine crystals, high particle size concentration, and few non-rare earth impurities. The process of the present invention is simple and reasonable, the device structure is simple, the operation is convenient, and the maintenance is easy. The investment is small and the effect is good, which is beneficial for enterprises to reduce production costs and increase profits.

[0042] The grading unloading trough includes a grading zone and a discharge zone. The particle size corresponding to the sedimentation rate of the grading zone is greater than the particle size of 80% of the mass fraction in the crystallized rare earth carbonate slurry. The grading zone includes a slurry transfer trough, and the discharge zone includes a slurry transfer trough.

[0043] Specifically, by setting up the grading zone, the crystals are suspended in the grading zone in the form of a dynamic bed, where particles with a mass fraction lower than 80% are carried away by the fluid because their particle size is smaller than the particle size corresponding to the sedimentation rate of the grading zone, that is, the sedimentation rate of particles with a mass fraction lower than 80% is lower than the flow rate of the grading zone, and are finally pumped back to the activation configuration tank, while particles with a mass fraction higher than 80% have a particle size larger than the particle size corresponding to the sedimentation rate of the grading zone, and are thus settled to the discharge zone and pumped to a vacuum belt filter for further processing to obtain large particles of rare earth carbonate; and the obtained precipitated crystal slurry is graded and discharged, that is, part of the fine crystal precipitate is pumped into the activation configuration tank for use as a seed crystal, and the other part is dried by centrifugal filtration to obtain rare earth carbonate; thereby, the crystal form control of the rare earth carbonate precipitate is achieved as a whole, so that the obtained rare earth carbonate product has large particles, high specific gravity, good operation continuity, and high labor productivity. Moreover, because of the continuous production, the reaction has extremely strong continuity, so that the produced product has high consistency.

[0044] The following is further introduced in conjunction with specific embodiments:

[0045] Embodiment 1:

[0046] A method for continuous preparation of rare earth compounds by precipitation, comprising the following steps:

[0047] S1, dilution activation: adding fine crystal slurry, rare earth feed liquid and recycled sedimentation wastewater into the activation configuration tank through a flow controller, wherein the fine crystal slurry includes the fine crystal grains in step S5, the addition amount of the fine crystal slurry is 15% of the amount of rare earth aging tank, the concentration of rare earth ions in the rare earth feed liquid is 1.2 mol / L, and then stirring treatment is performed, the stirring speed is 50r / min, and the reaction temperature is 40°C, thereby obtaining a mixed solution, and the concentration of rare earth ions in the mixed solution is 0.5 mol / L;

[0048] S2, crystal nucleus growth, the mixed solution overflows into the growth precipitation tank, and then the ammonium carbonate solution is added and stirred, the stirring speed is 80r / min, the reaction temperature is 60°C, the slurry pH is 4.8-5.5, and the reaction time is 1 hour, thereby obtaining a crystal nucleus growth slurry;

[0049] S3, complete crystallization: overflow the slurry into the crystallization precipitation tank through the crystal nucleus growth, and then add the ammonium carbonate solution again and stir it. The stirring speed is 80r / min, the reaction temperature is 60°C, the pH of the slurry is 6.4-6.8, and the reaction time is 0.5 hours, thereby obtaining a completely crystallized slurry. The rare earth content in the supernatant of the completely crystallized slurry is less than 0.07g / L;

[0050] S4. Static aging: The completely crystallized slurry overflows into an aging sedimentation tank, a precipitant is added and stirred, the stirring speed is 20r / min, the reaction temperature is 40°C, the slurry pH is 6.4-6.8, the aging time is greater than 2 hours, and the precipitant is a mixture of one or more of ammonium bicarbonate and ammonia water, with a concentration of 0.5-1.5 mol / L, thereby obtaining a crystallized rare earth carbonate slurry.

[0051] S5. Gradual unloading: The crystallized rare earth carbonate slurry overflows into the graded unloading tank, and the fine crystals in the crystallized rare earth carbonate slurry are drained to the crystal slurry transfer tank through the rare earth liquid, and are transported back to the activation configuration tank by a pump; the remaining crystallized rare earth carbonate slurry is transported to the slurry transfer tank through the unloading port, and then transported to the vacuum belt filter by a pump for filtration, so as to obtain large-particle rare earth carbonate.

[0052] Embodiment 2:

[0053] A method for continuous preparation of rare earth compounds by precipitation, comprising the following steps:

[0054] S1, dilution activation: adding fine crystal slurry, rare earth feed liquid and recycled sedimentation wastewater into the activation configuration tank through a flow controller, wherein the fine crystal slurry includes the fine crystal grains in step S5, the addition amount of the fine crystal slurry is 20% of the amount of rare earth aging tank, the concentration of rare earth ions in the rare earth feed liquid is 1.5 mol / L, and then stirring treatment is performed, the stirring speed is 60r / min, and the reaction temperature is 40°C, thereby obtaining a mixed solution, and the concentration of rare earth ions in the mixed solution is 0.8 mol / L;

[0055] S2, crystal nucleus growth, the mixed solution overflows into the growth precipitation tank, and then the ammonium carbonate solution is added and stirred, the stirring speed is 100r / min, the reaction temperature is 80°C, the slurry pH is 4.8-5.5, and the reaction time is 1 hour, thereby obtaining a crystal nucleus growth slurry;

[0056] S3, complete crystallization: overflow the slurry into the crystallization precipitation tank through the crystal nucleus growth, and then add the ammonium carbonate solution again and stir the mixture. The stirring speed is 100r / min, the reaction temperature is 80°C, the pH of the slurry is 6.4-6.8, and the reaction time is 0.5 hours, thereby obtaining a completely crystallized slurry. The rare earth content in the supernatant of the completely crystallized slurry is less than 0.07g / L;

[0057] S4. Static aging: The completely crystallized slurry overflows into an aging sedimentation tank, a precipitant is added and stirred, the stirring speed is 20r / min, the reaction temperature is 40°C, the slurry pH is 6.4-6.8, the aging time is greater than 3 hours, and the precipitant is a mixture of one or more of ammonium bicarbonate and ammonia water, with a concentration of 0.5-1.5 mol / L, thereby obtaining a crystallized rare earth carbonate slurry.

[0058] S5. Gradual unloading: The crystallized rare earth carbonate slurry overflows into the graded unloading tank, and the fine crystals in the crystallized rare earth carbonate slurry are drained to the crystal slurry transfer tank through the rare earth liquid, and are transported back to the activation configuration tank by a pump; the remaining crystallized rare earth carbonate slurry is transported to the slurry transfer tank through the unloading port, and then transported to the vacuum belt filter by a pump for filtration, so as to obtain large-particle rare earth carbonate.

[0059] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for continuous preparation of rare earth compounds by precipitation, characterized in that: The following steps are involved: S1. Dilution and activation: adding fine crystal slurry, rare earth liquid and recycled sedimentation wastewater into the activation configuration tank through a flow controller, and then stirring to obtain a mixed solution; S2, crystal nucleus growth: the mixed solution overflows into the growth precipitation tank, and then the ammonium carbonate solution is added and stirred to obtain a crystal nucleus growth slurry; S3, complete crystallization: the crystal nucleus growth slurry overflows into the crystallization precipitation tank, and then the ammonium carbonate solution is added again and stirred to obtain a completely crystallized slurry; S4, static aging: the completely crystallized slurry overflows into an aging sedimentation tank, a precipitant is added and stirred, thereby obtaining a crystallized rare earth carbonate slurry; S5. Gradual unloading: The crystallized rare earth carbonate slurry overflows into the graded unloading tank, and the fine crystals in the crystallized rare earth carbonate slurry are drained to the crystal slurry transfer tank through the rare earth liquid, and are transported back to the activation configuration tank by a pump; the remaining crystallized rare earth carbonate slurry is transported to the slurry transfer tank through the unloading port, and then transported to the vacuum belt filter by a pump for filtration, so as to obtain large-particle rare earth carbonate.

2. The method for continuous preparation of rare earth compounds by precipitation according to claim 1, characterized in that: The fine crystal slurry in step S1 includes the fine crystal grains in step S5, and the stirring process includes a stirring speed of 50-120 r / min and a reaction temperature of 40° C.-80° C.

3. The method for continuous preparation of rare earth compounds by precipitation according to claim 1, characterized in that: The stirring treatment in step S2 includes a stirring speed of 50-120 r / min, a reaction temperature of 40° C.-80° C., a slurry pH of 4.8-5.5, and a reaction time of 0.5-1 hour.

4. The method for continuous preparation of rare earth compounds by precipitation according to claim 1, characterized in that: The stirring treatment in step S3 includes a stirring speed of 50-120 r / min, a reaction temperature of 40°C-80°C, a slurry pH of 6.4-6.8, a reaction time of 0.5-1 hour, and a rare earth content in the supernatant of the completely crystallized slurry is less than 0.07 g / L.

5. The method for continuous preparation of rare earth compounds by precipitation according to claim 1, characterized in that: The stirring treatment in step S4 includes a stirring speed of 20-40 r / min, a reaction temperature of 40° C.-80° C., a slurry pH of 6.4-6.8, an aging time of 0.5-1 hour, and the precipitant is a mixture of one or more of ammonium bicarbonate and ammonia water, with a concentration of 0.5-1.5 mol / L.

6. The method for continuous preparation of rare earth compounds by precipitation according to claim 1, characterized in that: The amount of fine crystal slurry added in step S1 is 15%-25% of the amount of rare earth aging tank, the concentration of rare earth ions in the rare earth feed liquid is 1.2-1.8 mol / L, and the concentration of rare earth ions in the mixed liquid is 0.2-0.8 mol / L.

7. The method for continuous preparation of rare earth compounds by precipitation according to claim 1, characterized in that: The activation configuration tank, growth sedimentation tank, crystallization sedimentation tank, and aging sedimentation tank are all provided with pH meters, and the growth sedimentation tank and the crystallization sedimentation tank are both provided with ammonium carbonate flow meters on one side. The ammonium carbonate flow meters on the growth sedimentation tank and the crystallization sedimentation tank are connected to the pH meters inside the growth sedimentation tank and the crystallization sedimentation tank.

8. The method for continuous precipitation of rare earth compounds according to claim 1, characterized in that: The grading unloading trough includes a grading zone and a discharge zone. The particle size corresponding to the sedimentation rate of the grading zone is greater than the particle size of 80% of the mass fraction in the crystallized rare earth carbonate slurry. The grading zone includes a slurry transfer trough, and the discharge zone includes a slurry transfer trough.

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