Bayer stone granularity regulation and control method and Bayer stone product

Abstract

The invention relates to the technical field of aluminum oxide material preparation, in particular to a Bayer stone granularity regulation and control method and a Bayer stone product. The regulation and control method comprises the following steps: grinding a grinding medium and slurry containing Bayer stone seed crystals, and optimizing the particle size distribution of the Bayer stone seed crystals through the grinding medium to obtain grinding slurry with preset solid content; mixing the sodium aluminate solution with the grinding slurry with the preset solid content to obtain mixed slurry; carbon dioxide gas and the mixed slurry are subjected to a carbonization neutralization reaction, and neutralized slurry containing Bayer stone is obtained; and sequentially filtering and washing the neutralized slurry containing the Bayer stone to obtain a Bayer stone product. The core of the regulation and control method for improving the particle size adjustability of the Bayer stone is that the particle size and distribution of the seed crystal are optimized through grinding pretreatment, so that the particle size of a final product is more accurately controlled in the subsequent carbon decomposition (carbonization neutralization) process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alumina material preparation, and particularly relates to a bayerite particle size regulation method and a bayerite product. BACKGROUND

[0002] As a key variant of aluminum hydroxide, bayerite plays an important role in many industrial fields such as catalyst preparation and material synthesis. With the increasing demand for dehydrogenation and other catalytic fields, the demand for bayerite is increasing. Since the particle size of bayerite can significantly affect the subsequent catalytic reaction process, the particle size of bayerite is one of the key indicators that determine the performance and application effect of bayerite products.

[0003] However, the current control method for the particle size of bayerite is still lacking, which makes the particle size of bayerite uneven and difficult to meet the use requirements of fine chemical industry. SUMMARY

[0004] The present application provides a bayerite particle size regulation method and a bayerite product to solve the technical problem of how to improve the controllability of the particle size of bayerite.

[0005] In a first aspect, the embodiments of the present application provide a bayerite particle size regulation method, which comprises the following steps:

[0006] Grinding the grinding medium with the slurry containing bayerite seeds to optimize the particle size distribution of the bayerite seeds by the grinding medium, and obtaining a grinding material slurry with a preset solid content;

[0007] Mixing a sodium aluminate solution and the grinding material slurry with a preset solid content to obtain a mixed slurry;

[0008] Performing carbonation and neutralization reaction on the mixed slurry and carbon dioxide gas to obtain a neutralized slurry containing bayerite;

[0009] Filtering and washing the neutralized slurry containing bayerite in sequence to obtain a bayerite product.

[0010] Optionally, the particle size of the grinding medium is 0.4mm to 1.2mm; and / or

[0011] The types of the grinding medium include zirconium balls and / or zirconium alloy balls.

[0012] Optionally, the rotation speed of the grinding is 50r / min to 300r / min, and the duration of the grinding is 1h to 12h.

[0013] Optionally, the slurry containing the bayerite seed crystals comprises a bayerite seed crystal solid phase and a liquid phase solvent, a mass m1 of the bayerite seed crystal solid phase and a mass m2 of the liquid phase solvent satisfy: m1:m2=(1 to 5):(5 to 15).

[0014] Optionally, a mass m1 of the bayerite seed crystal solid phase and a mass m3 of the grinding medium satisfy: m1:m3=(1 to 5):(10 to 30).

[0015] Optionally, a volume V1 of the grinding material slurry and a volume V2 of the sodium aluminate solution satisfy: V1:V2=1:(25 to 65).

[0016] Optionally, the sodium aluminate solution has a caustic ratio of 1.2 to 2.0; and / or

[0017] The sodium aluminate solution has an alumina content of 20 g / L to 100 g / L.

[0018] Optionally, the preset solid content is 10% to 30%.

[0019] Optionally, the pH of the neutralization slurry is 12.8 to 13.8.

[0020] In a second aspect, the embodiments of the present application provide a bayerite product, which is prepared by the regulation method of the first aspect, the fine end particle size of the bayerite product is 10.55 μm to 29.02 μm, the median particle size of the bayerite product is 20.11 μm to 59.47 μm, and the coarse end particle size of the bayerite product is 57.51 μm to 108.86 μm.

[0021] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0022] The bayerite particle size regulation method provided by the embodiments of the present application first uses a grinding medium to grind the slurry containing the bayerite seed crystals, the grinding medium can reduce the seed crystal particle size distribution range of the bayerite seed crystals and improve the surface characteristics of the bayerite seed crystals, so as to optimize the bayerite seed crystals; then the optimized bayerite seed crystals, the sodium aluminate solution and the carbon dioxide gas are subjected to carbonization and neutralization reaction, under the induction of the bayerite seed crystals, the aluminum ions of the sodium aluminate solution can deposit and directionally grow on the surface of the bayerite seed crystals with different particle size distribution ranges, and bayerite products with different particle size ranges can be obtained, thereby improving the controllability of the bayerite products. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one embodiment consistent with the present application and, together with the description, serve to explain the principles of the application.

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, for those skilled in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0025] Figure 1 A flowchart of a bayer stone particle size control method provided by the embodiments of the present application;

[0026] Figure 2 A scanning electron microscope result graph of a bayer stone product provided by the embodiments of the present application. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application.

[0028] The range descriptions described in the present application, such as numerical range, ratio range, etc., all include all possible sub-ranges and single values within the range, for example, the range description of "1 to 6" or "1-6" covers all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "comprise" and the like used in the present application mean "including but not limited to". The relationship terms "first", "second", etc. are only used to distinguish different entities or operations, and do not imply actual sequence or relationship. "And / or" means that multiple cases can exist independently or simultaneously. "At least one", "multiple", "at least one", etc. refer to any combination of the corresponding objects, including single or multiple combinations of objects. The proportional relationship involved in the present application, such as mass ratio, molar ratio, etc., should be understood as the corresponding relationship between the front and rear terms in the proportional form according to the sequence of description. The raw materials, reagents, instruments and equipment used in the present application can be purchased or prepared by existing methods.

[0029] It should be noted that homogeneous nucleation and heterogeneous nucleation are two core mechanisms of the alumina crystallization process, wherein homogeneous nucleation is completely dependent on the supersaturation of the aluminum ion-containing solution, which makes homogeneous nucleation need to overcome the high interfacial energy of the aluminum ion-containing solution, and also need to avoid the random formation of crystal nucleus of mesocrystal phase. The typical homogeneous nucleation is the neutralization and decomposition system of carbon dioxide and ammonium aluminate solution, which presents the characteristics of low nucleation rate, small crystal nucleus size (<100 nm) and wide particle size distribution; and heterogeneous nucleation mainly reduces the nucleation energy barrier through external interfaces (such as seeds, impurities), and can form crystal nucleus at the interface under lower supersaturation. In the present application, the heterogeneous nucleation of bayerite is controlled by optimizing the bayerite seed and adding the bayerite into the above neutralization and decomposition system, which shows the advantages of high nucleation rate, large crystal nucleus size (1 μm to 10 μm) and controllable particle size distribution.

[0030] In addition, in the strong alkaline (pH>12) sodium aluminate solution, bayerite β-Al(OH)3 is a thermodynamic metastable phase, and its Gibbs free energy is significantly higher than that of the stable phase gibbsite α-Al(OH)3. The system has a thermodynamic driving force for transformation to the stable phase, but is limited by the kinetic energy barrier, and can still maintain a metastable state in the short term. In addition, based on the Ostwald ripening theory, the specific surface area of small particle size seeds (<1 μm) will increase exponentially, which will lead to an exponential increase in the dissolution rate, and the effective seed concentration will decay rapidly, while the surface active site distribution density of large particle size seeds (>5 μm) is insufficient. This shows that controlling the particle size of the seed is directly related to the stable state of the bayerite.

[0031] Therefore, the present application first controls the particle size of the seed by grinding to make the bayerite seed distribute in the range of 1 μm to 5 μm, and constructs the optimal particle size distribution window of the bayerite seed. The bayerite seed with a fine end particle size (the particle size value at which the cumulative distribution of particles in the bayerite product reaches 10%) of about 1 μm can provide a high density of nucleation sites to induce the homogeneous growth of bayerite crystals in the sodium aluminate solution, while the medium particle size (the particle size value at which the cumulative distribution of particles in the bayerite product reaches 50%) of about 3 μm can dominate the epitaxial growth of bayerite crystals through the interface step propagation mechanism, which can introduce a high density of dislocations and step edges on the surface of the bayerite seed, thereby reducing the activation energy of bayerite heterogeneous nucleation, inhibiting the multi-mode growth of aluminum ions in the sodium aluminate solution, and making the sodium aluminate solution directional transform into the bayerite product. The coarse end particle size (the particle size value at which the cumulative distribution of particles in the bayerite product reaches 90%) of less than 60 μm can effectively inhibit the homogeneous nucleation trend of the sodium aluminate solution, and ensure that the particle size of the bayerite product is highly controllable.

[0032] Figure 1 An example of a bayerite particle size regulation method provided by the embodiment of the present application is shown in the flowchart;

[0033] As Figure 1 shown, the embodiment of the present application provides a bayerite particle size control method, the control method comprising:

[0034] S1. Grinding the grinding medium with the slurry containing bayerite seed crystals, optimizing the particle size distribution of the bayerite seed crystals by the grinding medium, and obtaining a grinding material slurry with a preset solid content;

[0035] S2. Mixing sodium aluminate solution and the grinding material slurry with a preset solid content to obtain a mixed slurry;

[0036] S3. Carbonation neutralization reaction of carbon dioxide gas and the mixed slurry to obtain a neutralization slurry containing bayerite;

[0037] S4. Filtering and washing the neutralization slurry containing bayerite in sequence to obtain a bayerite product.

[0038] It should be noted that the grinding can be carried out under stirring conditions.

[0039] It should be noted that the bayerite particle size control method provided by the embodiment of the present application, the core of which is to optimize the particle size and distribution of the seed crystal by pre-treatment grinding, so as to realize more accurate control of the particle size of the final product in the subsequent carbon decomposition (carbonation neutralization) process. The specific principle is as follows:

[0040] 1. Grinding medium optimizes seed particle size distribution:

[0041] (1) Key step: grinding bayerite seed crystals with grinding medium.

[0042] (2) Effect:

[0043] Reduce the particle size of the seed crystal: grinding can effectively break the larger seed crystal particles and reduce the average particle size.

[0044] Narrow the particle size distribution: grinding can make the size of seed crystal particles more uniform, reducing the proportion of too coarse or too fine particles.

[0045] Improve the surface properties of the seed crystal: grinding may activate the surface of the bayerite seed crystal, increase the surface energy or provide more nucleation / growth sites.

[0046] (3) Purpose: obtain a grinding material slurry with a preset solid content and accurate control of particle size distribution (including average particle size and distribution width). This step directly determines the initial state of the seed crystal in the subsequent reaction.

[0047] 2. Optimize the control of the seed crystal on the carbonation decomposition process:

[0048] During the carbonation decomposition of sodium aluminate solution (supersaturated sodium aluminate solution), the main role of bayerite seed crystals is to provide growth surfaces to induce the deposition of aluminate ions from the solution onto their surfaces to form new bayerite crystals, thus inhibiting the spontaneous nucleation of sodium aluminate solution.

[0049] (1) Importance of seed particle size distribution:

[0050] Fine and narrow-distributed bayerite seed crystals: provide a large total surface area and a large number of uniform growth sites. This is conducive to the uniform growth of aluminate ions on existing particles, inhibits the formation of new crystal nuclei (reduces fine particles), and promotes more uniform particle growth. It is easier to obtain a product with a concentrated particle size distribution and an average particle size that meets the preset target (which can usually be adjusted by controlling the fineness of the seed crystals, the amount added, and the reaction conditions).

[0051] (2) Coarse or wide-distributed bayerite seed crystals: relatively small total surface area and uneven growth sites. This can lead to:

[0052] Excessive growth in some areas (may form oversized particles or agglomerates);

[0053] Insufficient growth in some areas;

[0054] Solution supersaturation cannot be effectively consumed, inducing spontaneous nucleation (producing a large number of fine particles);

[0055] The final product has a wide particle size distribution, making it difficult to accurately control the target particle size.

[0056] 3. Importance of preset solids content:

[0057] During the mixing step, the mill slurry is required to have a preset solids content. This ensures that the amount (mass or particle number) of bayerite seed crystals added to the sodium aluminate solution is accurately controllable.

[0058] The amount of seed crystals (i.e., solids content) directly affects the decomposition process:

[0059] High seed crystal amount: provides a large growth surface area, which is conducive to inhibiting nucleation and promoting particle growth, but may result in smaller final particles (if the seed crystals themselves are fine).

[0060] Low seed crystal amount: provides insufficient growth surface area, which easily induces spontaneous nucleation and produces fine particles, resulting in a wide distribution.

[0061] Combining the preset solids content and the accurate particle size distribution of the ground seed crystals, the total surface area and particle number of the bayerite seed crystals added to the system can be accurately controlled, which is a key parameter for achieving adjustable particle size.

[0062] 4. Carbonation neutralization reaction:

[0063] Passing into CO2 gas and sodium aluminate solution, reducing its alkalinity, making aluminate ion precipitation.

[0064] In the presence of the optimized bayerite seed, the precipitated aluminum mainly deposits on the surface of the bayerite seed, making it grow into the target bayerite particles.

[0065] Due to the narrow particle size distribution, good surface activity and accurate quantity (solid content) of the bayerite seed, the whole growth process is more controllable and uniform, and the generation of fine particles (less nucleation) and excessively coarse particles (uniform growth) is significantly reduced.

[0066] 5. Subsequent treatment:

[0067] The filtration and washing steps remove the mother liquor and impurities to obtain the final bayerite product. Through the accurate control of the previous steps, the particle size distribution of the product is also more in line with the preset requirements.

[0068] Therefore, the bayerite particle size control method provided by the embodiments of the present application realizes the particle size control of the bayerite product through the following control mechanism:

[0069] (1) Active control of initial conditions: Instead of relying on the uncontrollable particle size of the original seed, the seed is actively adjusted to the preset ideal particle size distribution (fine and narrow) through grinding.

[0070] (2) Accurate control of key variables: The preset solid content ensures the accurate quantity of the added bayerite seed. Grinding ensures the accurate quality (particle size and distribution) of the seed.

[0071] (3) Optimization of decomposition kinetics: The optimized bayerite seed provides a large, uniform and controllable growth surface, in the carbonization decomposition process:

[0072] Effectively inhibits the spontaneous nucleation of the sodium aluminate solution, reducing fine powder;

[0073] Promotes the uniform deposition and growth of aluminate ions on existing particles, reduces abnormal growth or agglomeration, and obtains more uniform particle size;

[0074] Improves the predictability and stability of the reaction process.

[0075] Particle size target can be set: By adjusting the grinding parameters (time, intensity, medium type, etc.), the target particle size distribution of the bayerite seed can be controlled. Combined with adjusting the amount of bayerite seed (solid content) and the carbonization reaction conditions (CO2 passing rate, temperature, time, etc.), the target particle size of the final bayerite product can be flexibly preset and realized (for example, when a coarser product is needed, slightly coarser ground seed or appropriate reduction of seed quantity can be used; when a finer product is needed, finer grinding or increased seed quantity can be used).

[0076] In short, the core advantage of the regulation method is that the uncontrollable bayerite crystal seeds are changed into "seeds" with precisely controllable particle size distribution through the pre-arranged grinding step, and then the subsequent decomposition and growth process becomes highly controllable and predictable by pre-setting the solid content, thereby greatly improving the adjustability of the particle size of the final bayerite product.

[0077] In some optional embodiments, the particle size of the grinding medium is 0.4 mm to 1.2 mm; and / or

[0078] The type of the grinding medium includes zirconium balls and / or zirconium alloy balls.

[0079] In these embodiments, the grinding medium with a particle size of 0.4 mm to 1.2 mm can sufficiently optimize the surface features of the bayerite crystal seeds to activate the surface of the bayerite crystal seeds, thereby increasing the surface energy of the bayerite crystal seeds or providing more nucleation / growth sites; in addition, using zirconium balls and / or zirconium alloy balls as the grinding medium can provide sufficient hardness and roughness to the grinding medium, which is conducive to the grinding medium optimizing the surface of the bayerite crystal seeds in the grinding stage, thereby effectively increasing the surface energy of the bayerite crystal seeds or providing more nucleation / growth sites.

[0080] The particle size of the grinding medium can be 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm or 1.2 mm.

[0081] It should be noted that when the particle size of the grinding medium is less than 0.4 mm, the particle size of the grinding medium is too small at this time, which will make the effect of the grinding stage excessive, resulting in a large amount of sub-micron crystal seeds in the bayerite crystal seeds. Due to the high instability of bayerite, these sub-micron bayerite crystal seeds are quickly dissolved, thereby failing to play the induction effect of the bayerite crystal seeds. When the particle size of the grinding medium is greater than 1.2 mm, the particle size of the grinding medium is too large at this time, which makes the grinding effect of the bayerite crystal seeds too low, resulting in uneven particle size distribution of the bayerite crystal seeds, which affects the particle size regulation of the final bayerite product.

[0082] In some optional embodiments, the rotation speed of the grinding is 50 r / min to 300 r / min, and the duration of the grinding is 1 h to 12 h.

[0083] In these embodiments, the grinding with a rotation speed of 50 r / min to 300 r / min and a duration of 1 h to 12 h can enable the grinding medium to effectively act on the surface of the bayerite crystal seeds to optimize the surface of the bayerite crystal seeds, thereby effectively increasing the surface energy of the bayerite crystal seeds or providing more nucleation / growth sites.

[0084] The rotation speed of the grinding can be 50 r / min, 100 r / min, 150 r / min, 200 r / min, 250 r / min, or 300 r / min.

[0085] The duration of the grinding can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, or 12 h.

[0086] It should be noted that, in the case where the rotation speed of the grinding is less than 50 r / min, the grinding medium cannot be effectively mixed with the bayerite crystal seeds, resulting in insufficient optimization of the bayerite crystal seeds and an excessively large particle size of the overall bayerite crystal seeds, affecting the subsequent particle size regulation of the bayerite product; in the case where the rotation speed of the grinding is greater than 300 r / min, the grinding medium excessively interacts with the bayerite, resulting in a large number of sub-micron bayerite crystal seeds, and due to the high instability of bayerite, these sub-micron bayerite crystal seeds are rapidly dissolved, thereby failing to exert the induction effect of the bayerite crystal seeds.

[0087] In the case where the duration of the grinding is less than 1 h, the grinding medium cannot be effectively mixed with the bayerite crystal seeds, resulting in insufficient optimization of the bayerite crystal seeds and an excessively large particle size of the overall bayerite crystal seeds, affecting the subsequent particle size regulation of the bayerite product; in the case where the duration of the grinding is greater than 12 h, the grinding medium excessively interacts with the bayerite, resulting in a large number of sub-micron bayerite crystal seeds, and due to the high instability of bayerite, these sub-micron bayerite crystal seeds are rapidly dissolved, thereby failing to exert the induction effect of the bayerite crystal seeds.

[0088] In some optional embodiments, the slurry containing the bayerite crystal seeds includes a bayerite crystal seed solid phase and a liquid phase solvent, and the mass m1 of the bayerite crystal seed solid phase and the mass m2 of the liquid phase solvent satisfy: m1:m2=(1 to 5):(5 to 15).

[0089] In these embodiments, the bayerite crystal seed solid phase and the liquid phase solvent in a mass ratio of (1 to 5):(5 to 15) can make there be sufficient bayerite crystal seeds in the slurry, while facilitating the mixing of the grinding medium with the bayerite crystal seeds in the grinding stage.

[0090] The mass m1 of the bayerite crystal seed solid phase can be 1, 2, 2, 3, 4, or 5.

[0091] The mass m2 of the liquid phase solvent can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15.

[0092] It should be noted that when the mass m1 of the bayerite seed crystal solid phase and the mass m2 of the liquid phase solvent satisfy: m1:m2<1:15, the liquid phase solvent is difficult to mix with the bayerite seed crystal sufficiently, resulting in low grinding efficiency in the grinding stage, and finally resulting in too large particle size of the bayerite seed crystal, affecting the particle size distribution range of the final bayerite product; when the mass m1 of the bayerite seed crystal solid phase and the mass m2 of the liquid phase solvent satisfy: m1:m2>5:5, the mass ratio of the bayerite seed crystal to the liquid phase solvent is too large, which makes the resistance of the slurry in the grinding stage too large, making it difficult to grind sufficiently, resulting in too large particle size of the bayerite seed crystal.

[0093] It should be noted that the liquid phase solvent can be water.

[0094] In some optional embodiments, the mass m1 of the bayerite seed crystal solid phase and the mass m3 of the grinding medium satisfy: m1:m3=(1 to 5):(10 to 30).

[0095] In these embodiments, the bayerite seed crystal solid phase and the grinding medium with a mass ratio of (1 to 5):(10 to 30) can effectively improve the surface of the bayerite seed crystal, thereby increasing the surface energy of the bayerite seed crystal or providing more nucleation / growth sites.

[0096] The mass m1 of the bayerite seed crystal solid phase can be 1, 2, 2, 3, 4, or 5.

[0097] The mass m3 of the grinding medium can be 10, 15, 20, 25, or 30.

[0098] It should be noted that when the mass m1 of the bayerite seed crystal solid phase and the mass m3 of the grinding medium satisfy: m1:m3<1:30, the grinding medium is too much, which causes excessive grinding, resulting in a large number of submicron seed crystals of bayerite, due to the high instability of bayerite, these submicron bayerite seed crystals are quickly dissolved, so that the induction effect of the bayerite seed crystal cannot be played; when the mass m1 of the bayerite seed crystal solid phase and the mass m3 of the grinding medium satisfy: m1:m3>5:10, the grinding medium is insufficient, resulting in poor grinding effect, making the particle size of the bayerite seed crystal too large, affecting the particle size controllability of the final bayerite product.

[0099] In some optional embodiments, the volume V1 of the grinding material slurry and the volume V2 of the sodium aluminate solution satisfy: V1:V2=1:(25 to 65).

[0100] In these embodiments, the volume ratio of the grinding material slurry and the sodium aluminate solution of 1:(25-65) can make the bayerite seed crystals sufficient in the neutralization reaction of carbonization, so as to induce the aluminate ions in the sodium aluminate solution to grow towards the bayerite products of different particle sizes through the optimized bayerite seed crystals, thereby obtaining the bayerite products of different particle size distributions.

[0101] The volume V2 of the sodium aluminate solution can be 25, 30, 35, 40, 45, 50, 55, 60 or 65.

[0102] It should be noted that, in the case that the volume V1 of the grinding material slurry and the volume V2 of the sodium aluminate solution satisfy V1:V2<1:65, the bayerite seed crystals in the grinding material slurry are insufficient at this time, so that the induction effect of the bayerite seed crystals is poor, and the bayerite products of different particle size ranges cannot be generated; in the case that the volume V1 of the grinding material slurry and the volume V2 of the sodium aluminate solution satisfy V1:V2>1:25, the content of the bayerite seed crystals in the grinding material slurry is too much at this time, so that a large amount of seed crystals are doped in the final bayerite products, and it is difficult to obtain the shaped bayerite products.

[0103] In some optional embodiments, the caustic ratio of the sodium aluminate solution is 1.2-2.0; and / or

[0104] The alumina content of the sodium aluminate solution is 20-100 g / L.

[0105] In these embodiments, the sodium aluminate solution with a caustic ratio of 1.2-2.0 can promote the aluminate ions in the ammonium aluminate solution to be in a stable state, so that the sodium aluminate solution can form the bayerite products with a controllable particle size distribution range under the induction of the bayerite seed crystals in the grinding material slurry. In addition, the sodium aluminate solution with an alumina content of 20-100 g / L can make the sodium aluminate solution have sufficient aluminate ions, which can form the bayerite products of different particle size distribution ranges under the induction of the bayerite seed crystals in the grinding material slurry.

[0106] The caustic ratio of the sodium aluminate solution can be 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0.

[0107] The alumina content of the sodium aluminate solution can be 20, 30, 40, 50, 60, 70, 80, 90 or 100 g / L.

[0108] It should be noted that, in the case that the caustic ratio of the sodium aluminate solution is less than 1.2, this makes the aluminate ions in the sodium aluminate solution in a highly unstable state, under the induction of the bayerite seed crystals in the abrasive slurry, the aluminate ions will uncontrollably and rapidly decompose, resulting in a chaotic particle size distribution range of the bayerite product; in the case that the caustic ratio of the sodium aluminate solution is greater than 2.0, this makes the content of the alkaline substance (such as sodium oxide) in the sodium aluminate solution too high, in the high-alkalinity system, the bayerite will be converted into other impurity crystals or present uncontrollable growth.

[0109] It should be noted that, in the case that the alumina content of the sodium aluminate solution is less than 20 g / L, this makes the content of the aluminate ions in the sodium aluminate solution low, which is difficult to meet the production efficiency demand of the bayerite product; in the case that the alumina content of the sodium aluminate solution is greater than 100 g / L, this makes the content of the alumina too high, resulting in the viscosity of the sodium aluminate solution being too high, affecting the uniformity degree of the distribution of carbon dioxide in the subsequent carbonation neutralization reaction stage, and also causing the local temperature difference of the sodium aluminate solution to be too large, ultimately affecting the uniform dispersion of the bayerite product.

[0110] In some optional embodiments, the preset solid content is 10% to 30%.

[0111] In these embodiments, the preset solid content of 10% to 30% can make the abrasive slurry have sufficient bayerite seed crystals, guaranteeing that there are sufficient bayerite seed crystals in the subsequent carbonation neutralization reaction stage, which is beneficial to the formation of bayerite products with different particle size range distributions.

[0112] The preset solid content can be 10%, 15%, 20%, 25%, or 30%.

[0113] In some optional embodiments, the pH of the neutralization slurry is 12.8 to 13.8.

[0114] In these embodiments, the neutralization slurry with a pH of 12.8 to 13.8 can make the bayerite product in the neutralization slurry in a relatively stable state, which is beneficial to the subsequent filtration and washing, and facilitates the subsequent obtaining of pure bayerite products.

[0115] The pH of the neutralization slurry can be 12.8, 13.0, 13.2, 13.4, 13.6, or 13.8.

[0116] Figure 2 Exemplary scanning electron microscope result graphs of a bayerite product provided by the embodiments of the present application are shown;

[0117] Based on a general inventive concept, as Figure 2As shown, the embodiment of the present application provides a bayerite product, the bayerite product is prepared by the regulation method, the fine end particle size of the bayerite product is 10.55 μm to 29.02 μm, the median particle size of the bayerite product is 20.11 μm to 59.47 μm, and the coarse end particle size of the bayerite product is 57.51 μm to 108.86 μm.

[0118] The bayerite product is prepared based on the above regulation method, and the specific steps of the regulation method can refer to the above embodiment. Since the bayerite product adopts part or all of the technical solutions of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment, and will not be repeated here.

[0119] It should be noted that the fine end particle size is the particle size value at which the cumulative distribution of the bayerite product reaches 10%, the median particle size is the particle size value at which the cumulative distribution of the bayerite product reaches 50%, and the coarse end particle size is the particle size value at which the cumulative distribution of the bayerite product reaches 90%.

[0120] The present application will be further described in combination with specific embodiments. The experimental methods not specified in the following embodiments are generally determined according to national standards / industry standards; if there is no corresponding national standard / industry standard, the general international standard, conventional conditions or the conditions suggested by the manufacturer are used.

[0121] Embodiment 1

[0122] As shown, a bayerite particle size regulation method comprises: Figure 1

[0123] S1. Grinding the grinding medium with the slurry containing the bayerite seed crystal, optimizing the particle size distribution of the bayerite seed crystal by the grinding medium, and obtaining the grinding material slurry with a preset solid content;

[0124] S2. Mixing the sodium aluminate solution and the grinding material slurry with a preset solid content to obtain a mixed slurry;

[0125] S3. Carbonation neutralization reaction of carbon dioxide gas and mixed slurry to obtain a neutralization slurry containing bayerite;

[0126] S4. Filtering and washing the neutralization slurry containing bayerite in sequence to obtain a bayerite product.

[0127] The particle size of the grinding medium is 0.4 mm;

[0128] The type of grinding medium is zirconium ball.

[0129] The rotation speed of grinding is 100 r / min, and the duration of grinding is 4 h. ​

[0130] The slurry containing Bayerite seed crystals consists of a Bayerite seed crystal solid phase and a liquid solvent phase. The mass m1 of the Bayerite seed crystal solid phase and the mass m2 of the liquid solvent phase satisfy the following ratio: m1:m2 = 2:8.

[0131] The mass m1 of the Bayerite seed solid phase and the mass m3 of the grinding media satisfy the following ratio: m1:m3 = 2:15.

[0132] The volume V1 of the grinding slurry and the volume V2 of the sodium aluminate solution satisfy the following ratio: V1:V2 = 1:30.

[0133] The caustic ratio αk of the sodium aluminate solution is 1.4;

[0134] The alumina content of the sodium aluminate solution is 40 g / L.

[0135] The preset solid content is 10% to 30%.

[0136] The pH of the neutralized slurry is 13.0.

[0137] Example 2

[0138] Compared to Example 1, the differences in this example are as follows, while the rest are the same:

[0139] The particle size of the grinding media is 0.8 mm.

[0140] The grinding speed was 200 r / min, and the grinding duration was 8 h.

[0141] The slurry containing Bayerite seed crystals consists of a Bayerite seed crystal solid phase and a liquid solvent phase. The mass m1 of the Bayerite seed crystal solid phase and the mass m2 of the liquid solvent phase satisfy the following ratio: m1:m2 = 4:12.

[0142] The mass m1 of the Bayer stone seed solid phase and the mass m3 of the grinding media satisfy the following ratio: m1:m3 = 4:25.

[0143] The volume V1 of the grinding slurry and the volume V2 of the sodium aluminate solution satisfy: V1:V2=1:50.

[0144] The caustic ratio of the sodium aluminate solution is 1.8;

[0145] The alumina content of the sodium aluminate solution is 80 g / L.

[0146] The pH of the neutralized slurry is 13.8.

[0147] Example 3

[0148] Compared to Example 1, the differences in this example are as follows, while the rest are the same:

[0149] The particle size of the grinding media is 1.2 mm.

[0150] The rotation speed of the grinding is 150 r / min, and the duration of the grinding is 6 h.

[0151] The slurry containing bayerite seed crystals comprises a bayerite seed crystal solid phase and a liquid phase solvent, the mass m1 of the bayerite seed crystal solid phase and the mass m2 of the liquid phase solvent satisfy: m1:m2 = 3:10.

[0152] The mass m1 of the bayerite seed crystal solid phase and the mass m3 of the grinding medium satisfy: m1:m3 = 3:18.

[0153] The volume V1 of the grinding material slurry and the volume V2 of the sodium aluminate solution satisfy: V1:V2 = 1:40.

[0154] The caustic ratio of the sodium aluminate solution is 1.7;

[0155] The alumina content of the sodium aluminate solution is 70 g / L.

[0156] The pH of the neutralization slurry is 13.6.

[0157] Example 4

[0158] Compared with Example 1, the differences of the present example are as follows, and the rest are the same:

[0159] The rotation speed of the grinding is 250 r / min, and the duration of the grinding is 10 h.

[0160] The slurry containing bayerite seed crystals comprises a bayerite seed crystal solid phase and a liquid phase solvent, the mass m1 of the bayerite seed crystal solid phase and the mass m2 of the liquid phase solvent satisfy: m1:m2 = 3.5:11.

[0161] The mass m1 of the bayerite seed crystal solid phase and the mass m3 of the grinding medium satisfy: m1:m3 = 3.5:22.

[0162] The volume V1 of the grinding material slurry and the volume V2 of the sodium aluminate solution satisfy: V1:V2 = 1:45.

[0163] The caustic ratio of the sodium aluminate solution is 1.7;

[0164] The alumina content of the sodium aluminate solution is 70 g / L.

[0165] The pH of the neutralization slurry is 12.9.

[0166] Comparative Example 1

[0167] Compared with Example 2, the differences of the present example are as follows, and the rest are the same:

[0168] No grinding medium is added for grinding, and the slurry containing bayerite seed crystals formed by the bayerite seed crystals and water is directly used.

[0169] The slurry containing bayerite seed crystals comprises a bayerite seed crystal solid phase and a liquid phase solvent, the mass m1 of the bayerite seed crystal solid phase and the mass m2 of the liquid phase solvent satisfy: m1:m2=4:12.

[0170] The ratio of the volume of the slurry to the volume of the sodium aluminate solution is 1:50.

[0171] The caustic ratio of the sodium aluminate solution is 1.8;

[0172] The alumina content of the sodium aluminate solution is 80 g / L.

[0173] The pH of the neutralized slurry is 13.5.

[0174] Comparative Example 2

[0175] The difference between the present comparative example and Example 2 is as follows, and the rest are the same:

[0176] The particle size of the grinding medium is 0.2 mm.

[0177] Comparative Example 3

[0178] The difference between the present comparative example and Example 2 is as follows, and the rest are the same:

[0179] The particle size of the grinding medium is 2.0 mm.

[0180] Comparative Example 4

[0181] The difference between the present comparative example and Example 2 is as follows, and the rest are the same:

[0182] The rotation speed of the grinding is 30 r / min, and the duration of the grinding is 16 h.

[0183] Comparative Example 5

[0184] The difference between the present comparative example and Example 2 is as follows, and the rest are the same:

[0185] The rotation speed of the grinding is 500 r / min, and the duration of the grinding is 0.5 h.

[0186] Comparative Example 6

[0187] The difference between the present comparative example and Example 2 is as follows, and the rest are the same:

[0188] The mass m1 of the bayerite seed crystal solid phase and the mass m3 of the grinding medium satisfy: m1:m3=1:40.

[0189] Comparative Example 7

[0190] The difference between the present comparative example and Example 2 is as follows, and the rest are the same:

[0191] The mass m1 of the bayerite seed crystal solid phase and the mass m3 of the grinding medium satisfy: m1:m3=10:10.

[0192] Related experiments and effect data:

[0193] The bayerite products obtained in each example and the comparative example were collected respectively, and a Malvern Mastersizer 3000 laser particle size instrument was used to test the particle size distribution of the bayerite products after ultrasonic treatment for 3 min with anhydrous ethanol as a dispersion medium. The results are shown in Table 1.

[0194] Table 1 Particle size distribution range of the bayerite products obtained in each example and the comparative example

[0195]

[0196] As shown in Table 1, the bayerite particle size control method provided in the examples can change the uncontrollable bayerite seed crystal into a bayerite seed crystal with an accurate and controllable particle size distribution through a pre-grinding step, and then cooperate with a preset solid content, so that the subsequent decomposition and growth process becomes highly controllable and predictable, thereby greatly improving the adjustability of the particle size of the final bayerite product. The final bayerite product can have a fine end particle size d 10 of 10.55 μm to 29.02 μm, a median particle size d 50 of 20.11 μm to 59.47 μm, and a coarse end particle size d 90 of 57.51 μm to 108.86 μm.

[0197] Compared with Example 1, Comparative Example 1 does not use a grinding medium, which makes the fine end particle size d 10 of the final bayerite product 32.47 μm, the median particle size d 50 of 52.14 μm, and the coarse end particle size d 90 of 94.33 μm. The particle size range distribution of the bayerite product is narrow, and the particle size distribution of the bayerite product cannot be effectively controlled.

[0198] Compared with Example 1, Comparative Example 2 uses a smaller particle size of the grinding medium, which makes submicron bayerite seed crystals appear in the bayerite seed crystals, affecting the particle size distribution of the final bayerite product; and Comparative Example 3 uses a larger particle size of the grinding medium, which makes the grinding effect poor, affecting the particle size distribution of the final bayerite product.

[0199] Compared with Example 1, the lower grinding speed and the longer grinding duration used in Comparative Example 4 result in insufficient optimization of the bayerite seed crystals, and the overall particle size of the bayerite seed crystals is too large, which affects the subsequent particle size adjustment of the bayerite product; the higher grinding speed and the shorter grinding duration used in Comparative Example 5 result in insufficient optimization of the bayerite seed crystals, and part of the bayerite seed crystals are submicron, which greatly affects the particle size adjustment of the final bayerite product.

[0200] Compared with Example 1, the more grinding medium used in Comparative Example 6 results in excessive grinding stage, resulting in a large number of submicron seed crystals of bayerite, which affects the subsequent particle size adjustment of the bayerite product; the less grinding medium used in Comparative Example 7 results in insufficient grinding, and the grinding effect is poor, so that the particle size of the bayerite seed crystals is too large, which affects the particle size adjustability of the final bayerite product.

[0201] In summary, the bayerite particle size adjustment method provided in the embodiments of the present application improves the core of the particle size adjustability of the bayerite by optimizing the particle size and distribution of the seed crystals through the pre-treatment of grinding, so as to realize more accurate control of the particle size of the final product in the subsequent carbon decomposition (carbonization and neutralization) process.

[0202] In addition, the bayerite particle size adjustment method provided in the embodiments of the present application has stronger controllability and stability compared with the traditional method based on the pre-grinding stage and the parameters of the carbonization and neutralization reaction, effectively reduces the quality fluctuation of the bayerite product caused by uneven particle size, improves the production efficiency and product quality of the bayerite product, and reduces the production cost and resource waste of the bayerite product.

[0203] In addition, the bayerite product provided in the embodiments of the present application can be prepared to have a fine end particle size d 10 In 10.55 μm to 29.02 μm, the median particle size d 50 In 20.11 μm to 59.47 μm, the coarse end particle size d 90 The bayerite product with a particle size adjustable between 57.51 μm and 108.86 μm can meet the diversified needs of bayerite particle size in different industrial fields, and significantly improves the applicability and market competitiveness of the bayerite product.

[0204] The above description is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications of these embodiments will be apparent to those skilled in the art, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the present application, but will conform to the widest scope consistent with the principles and novel features of the present application.

Claims

1. A method for controlling the particle size of Bayerite, the method comprising: Grinding media are used to grind the slurry containing Bayerite seed crystals, and the particle size distribution of the Bayerite seed crystals is optimized by the grinding media to obtain a grinding slurry with a preset solid content. A sodium aluminate solution and the grinding slurry having a preset solid content are mixed to obtain a mixed slurry; Carbon dioxide gas and the mixed slurry are subjected to a carbonization and neutralization reaction to obtain a neutralized slurry containing Bayerite; The neutralized slurry containing Bayerite is filtered and washed sequentially to obtain the Bayerite product.

2. The control method according to claim 1, characterized in that, The abrasive media has a particle size of 0.4 mm to 1.2 mm; and / or The types of grinding media include zirconium balls and / or zirconium alloy balls.

3. The control method according to claim 1, characterized in that, The grinding speed is from 50 r / min to 300 r / min, and the grinding duration is from 1 h to 12 h.

4. The control method according to claim 1, characterized in that, The slurry containing Bayerite seeds comprises a Bayerite seed solid phase and a liquid solvent, wherein the mass m1 of the Bayerite seed solid phase and the mass m2 of the liquid solvent satisfy the following: m1:m2 = (1 to 5):(5 to 15).

5. The control method according to claim 4, characterized in that, The mass m1 of the Bayerite seed solid phase and the mass m3 of the grinding media satisfy the following: m1:m3 = (1 to 5):(10 to 30).

6. The control method according to claim 1, characterized in that, The volume V1 of the grinding slurry and the volume V2 of the sodium aluminate solution satisfy: V1:V2=1:(25 to 65).

7. The control method according to claim 1 or 6, characterized in that, The sodium aluminate solution has a caustic ratio of 1.2 to 2.0; and / or The sodium aluminate solution has an alumina content of 20 g / L to 100 g / L.

8. The control method according to claim 1, characterized in that, The preset solid content is 10% to 30%.

9. The control method according to claim 1, characterized in that, The pH of the neutralized slurry is between 12.8 and 13.

8.

10. A Bayer stone product, said Bayer stone product being prepared by the control method according to any one of claims 1 to 9, wherein the fine-end particle size of said Bayer stone product is 10.55 μm to 29.02 μm, the median particle size of said Bayer stone product is 20.11 μm to 59.47 μm, and the coarse-end particle size of said Bayer stone product is 57.51 μm to 108.86 μm.

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