Grading method and device for superfine inorganic powder

Abstract

The invention provides a grading method and device for superfine inorganic powder, the particle size of the superfine inorganic powder is smaller than 100 nm, the grading method comprises the following steps that S1, the superfine inorganic powder is added into deionized water, turbid liquid with the solid content being 10 wt%-30 wt% is obtained, stirring and dispersing are conducted for 1-10 h, and dispersion liquid is obtained; s2, adding a powder particle aggregation and dispersion regulating agent, carrying out oil bath and aging treatment for 2-10 hours, stirring, cooling to room temperature, filtering through at least one membrane module, and carrying out spray drying, so as to obtain at least two groups of powder with different particle size distribution; wherein the addition amount of the powder particle aggregation and dispersion regulating agent is 0.1-5 wt.% of the mass of the dispersion liquid, and the oil bath temperature is 50-120 DEG C. According to the grading method provided by the invention, by adding the powder particle aggregation and dispersion regulating agent, controlling the powder particle aggregation size and further combining a membrane separation technology, screening is carried out by utilizing a membrane with a specific pore diameter range in a cross-flow filtration mode, and accurate grading of the superfine powder is realized.

Description

Technical Field

[0001] The invention relates to the technical field of ultrafine powder classification, and in particular to a classification method and device for ultrafine inorganic powder. Background Art

[0002] In the field of medium and high temperature sintering, the classification of inorganic ceramic powders, especially ultrafine inorganic powders, plays a vital role. Through the precise classification of inorganic ceramic powders, powders with different particle size distributions can be mixed in an optimized ratio to achieve the best particle grading. This optimized particle grading can ensure the dense packing of ceramic powders and greatly reduce the amount of pores that need to be removed during the sintering process. Accurate particle grading not only increases the packing density of the material, but also makes the number and distribution of pores more uniform, making the pore removal speed more consistent. This largely avoids the incomplete removal caused by uneven pore distribution, thereby eventually forming a low-density ceramic body after sintering, affecting its mechanical and electrical properties.

[0003] To date, powder classification technology has mainly relied on simple physical principles for classification. These technologies are usually based on the difference in powder particle size or mass, and the methods used include centrifugation, spray drying, screening, etc. Although these methods are easy to operate, it is often difficult to achieve the ideal classification effect when dealing with ultrafine inorganic powders, especially powders with a particle size of 100 nanometers or even 50 nanometers. This is because traditional physical classification technology is limited by the inability to accurately control the agglomeration size and a large amount of dust when dealing with such fine particles, making it difficult to achieve accurate classification. Summary of the invention

[0004] In view of the defects in the prior art, the purpose of the present invention is to provide a classification method for ultrafine inorganic powders, a classification method based on the physical and chemical properties of the powder particle surface, by adding powder particle agglomeration dispersion regulator to control the powder particle agglomeration size, further combined with membrane separation technology, through cross-flow filtration, using a membrane with a specific pore size range for screening, to achieve accurate classification of ultrafine powders.

[0005] The first invention of the present invention provides a classification method for ultrafine inorganic powders, wherein the particle size of the ultrafine inorganic powders is below 100 nm, and the classification method comprises the following steps:

[0006] S1. Add ultrafine inorganic powder to deionized water, stir and disperse to obtain a suspension with a solid content of 10wt% to 30w%, continue stirring and dispersing for 1 to 10 hours to obtain a dispersion;

[0007] S2, adding powder particle agglomeration and dispersion regulating agent, oil bath, aging treatment for 2 to 10 hours, stirring, cooling to room temperature, filtering through at least one membrane component in turn, spray drying, to obtain at least two groups of powders with different particle size distributions; wherein the addition amount of the powder particle agglomeration and dispersion regulating agent is 0.1 to 5wt.% of the mass of the dispersion, and the oil bath temperature is 50 to 120°C.

[0008] In one embodiment of the present invention, the membrane components include three, namely a first membrane component, a second membrane component, and a third membrane component, and the pore sizes of the three membrane components are different.

[0009] In one embodiment of the present invention, after cooling to room temperature, the product is filtered in sequence through a first membrane assembly, a second membrane assembly, and a third membrane assembly, and the slurry that does not pass through the membrane layer after filtration by the first membrane assembly, the slurry that does not pass through the membrane layer after filtration by the second membrane assembly, the slurry that does not pass through the membrane layer after filtration by the third membrane assembly, and the slurry obtained by passing through the membrane layer after filtration by the third membrane assembly are spray dried respectively to obtain four groups of powders with different particle size distributions.

[0010] In one embodiment of the present invention, the powder particle agglomeration and dispersion regulator is a dispersant and / or a flocculant.

[0011] In one embodiment of the present invention, the powder particle agglomeration and dispersion control agent is at least one of PEG, PVA, PAA, and PAM.

[0012] In one embodiment of the present invention, the ultrafine inorganic powder is zirconium oxide powder with a particle size of less than 100 nm, the powder particle agglomeration and dispersion regulator is PEG600, the pore size of the first membrane component is 1 μm, the pore size of the second membrane component is 200 nm, and the pore size of the third membrane component is 50 nm.

[0013] In one embodiment of the present invention, the ultrafine inorganic powder is zirconium oxide powder with a particle size of less than 100 nm, the powder particle agglomeration and dispersion regulator is a mixture of PEG600 and PAA, the pore size of the first membrane component is 200 nm, the pore size of the second membrane component is 50 nm, and the pore size of the third membrane component is 10 nm.

[0014] In one embodiment of the present invention, the ultrafine inorganic powder is zirconium oxide powder with a particle size of less than 100 nm, the powder particle agglomeration and dispersion regulator is PAM, the pore size of the first membrane component is 5 μm, the pore size of the second membrane component is 500 nm, and the pore size of the third membrane component is 50 nm.

[0015] The second invention of the present invention provides a classification device for ultrafine inorganic powders, comprising a membrane assembly and a spray dryer connected to the liquid outlet end of the membrane assembly.

[0016] In one embodiment of the present invention, the membrane assembly is provided with three groups, namely, a first membrane assembly, a second membrane assembly, and a third membrane assembly; and further comprises three barrels, namely, a first barrel, a second barrel, and a third barrel;

[0017] The first material barrel, the first membrane assembly, the second material barrel, the second membrane assembly, the third material barrel, the third membrane assembly, and the spray dryer are connected in sequence;

[0018] The spray dryer further includes a delivery pipe connected to the first material barrel, the second material barrel, and the third material barrel respectively.

[0019] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0020] The ultrafine inorganic powder grading method provided by the present invention is a grading method based on the physical and chemical properties of the powder particle surface. By adding a powder particle agglomeration dispersion regulating agent, the powder particle agglomeration size is controlled. The membrane separation technology is further combined to screen by cross-flow filtration using a membrane with a specific pore size range to achieve accurate grading of ultrafine powders. Specifically, in the ultrafine inorganic powder grading method provided by the present invention, a powder particle agglomeration dispersion regulating agent is added, wherein the powder particle agglomeration dispersion regulating agent is a dispersant and / or a flocculant. The effect of dispersing the powder particles is achieved through the electrostatic stabilization or steric hindrance of the dispersant, while the flocculant adsorbs the powder particles on the molecular chain, and multiple powder particles aggregate and are easy to precipitate, thereby effectively controlling the degree of agglomeration between particles. Furthermore, through the aging effect brought about by heating, the size of the large agglomerated particles increases, and the small particles outside the agglomeration system continue to exist independently. Under the separation action of the membrane component, the separation of particles of different sizes is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0022] Figure 1 A schematic diagram of the structure of a device for classifying ultrafine inorganic powders provided in an embodiment of the present invention;

[0023] In the figure: first material barrel 1, second material barrel 2, third material barrel 3, first membrane assembly 4, second membrane assembly 5, third membrane assembly 6, spray dryer 7, valves (1-1, 1-2, 1-3, 2-1, 2-2, 2-3, 3-1, 3-2, 3-3, 4-1, 4-2, 4-3). DETAILED DESCRIPTION

[0024] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0025] Traditional physical classification technology is difficult to achieve accurate classification when dealing with such fine particles due to the inability to effectively control the agglomeration size and a large amount of dust.

[0026] Based on this, the present invention provides a classification method for ultrafine inorganic powders, wherein the particle size of the ultrafine inorganic powders is below 100 nm, and the classification method comprises the following steps:

[0027] S1. Add ultrafine inorganic powder to deionized water, stir appropriately to obtain a suspension with a solid content of 10wt% to 30w%, continue stirring and dispersing for 1 to 10 hours to obtain a dispersion;

[0028] S2, adding powder particle agglomeration and dispersion regulating agent, oil bath, aging treatment for 2 to 10 hours, stirring, cooling to room temperature, filtering through at least one membrane component in turn, spray drying, to obtain at least two groups of powders with different particle size distributions; wherein the addition amount of the powder particle agglomeration and dispersion regulating agent is 0.1 to 5wt.% of the mass of the dispersion, and the oil bath temperature is 50 to 120°C.

[0029] The ultrafine inorganic powder classification method provided by the present invention is a classification method based on the physical and chemical properties of the powder particle surface. The agglomeration size of the powder particles is controlled by adding different types of powder particle agglomeration dispersion regulators. This method combines membrane separation technology and uses a membrane with a specific pore size range for screening through cross-flow filtration. In this process, powder particles smaller than a certain size range are able to pass through the membrane layer, while powder particles larger than this size remain in the internal circulation of the equipment. In addition, these ultrafine nano powders with extremely narrow distribution ranges can be collected and dried through spray drying technology. This method achieves accurate classification of ultrafine powders and significantly improves their performance in industrial applications.

[0030] The present invention is further described below in conjunction with specific embodiments.

[0031] Example 1

[0032] Reference Figure 1 As shown, this embodiment provides a classification device for ultrafine inorganic nanopowders, including a membrane assembly and a spray dryer connected to the liquid outlet end of the membrane assembly.

[0033] The membrane assembly is provided with three groups, namely the first membrane assembly 4, the second membrane assembly 5, and the third membrane assembly 6; and also includes three barrels, namely the first barrel 1, the second barrel 2, and the third barrel 3;

[0034] The first material barrel 1, the first membrane assembly 4, the second material barrel 2, the second membrane assembly 5, the third material barrel 3, the third membrane assembly 6, and the spray dryer 7 are connected in sequence;

[0035] The spray dryer further comprises a delivery pipe respectively connected to the first barrel 1, the second barrel 2, the third barrel 3, the first membrane assembly 4, the second membrane assembly 5, and the third membrane assembly 6. Delivery pumps (1# pump, 2# pump, 3# pump) and valves (1-1, 1-2, 1-3, 2-1, 2-2, 2-3, 3-1, 3-2, 3-3, 4-1, 4-2, 4-3) are installed on the delivery pipe.

[0036] Example 2

[0037] This embodiment provides a classification method for ultrafine inorganic nanopowders, which is operated using the classification device described in Example 1, and the specific steps are as follows:

[0038] 200g of zirconium oxide powder was dispersed in 5L of deionized water, dispersed for 0.5h under stirring at 600rpm, and dispersant PEG600 was added according to Table 1. Stirring was continued for 2h. Under continued stirring, the suspension temperature was raised to 80°C for aging. After keeping warm for 5h, it was cooled. After cooling to room temperature, the suspension was poured into the first barrel 1, valves 1-1, 2-1, 3-1 were opened, valve 4-1 was closed, and pump 1# was opened until the volume of the suspension in the second barrel 2 no longer increased. Then valves 1-2, 2-2, 3-2 were opened, pump 2# was opened, and valve 4-2 was closed until the volume of the suspension in the third barrel 3 no longer increased. The spray dryer was turned on, valves 1-3, 2-3, 3-3 were opened, valve 4-3 was closed, pump 3# was opened, and the flow rate of the suspension entering the spray dryer was controlled by valve 3-3. The dried nano powder N-1 was collected at the receiving port below the spray dryer.

[0039] Table 1

[0040]

[0041] When no more suspension flows out of the discharge pipe of valve 3-3, clean the spray dryer. Open valve 4-3, spray dry the suspension in the third barrel 3, and collect submicron powder S-2. Then spray dry the suspension in the second barrel 2 and the first barrel 1 in turn, and collect submicron powders S-3 and S-4 respectively.

[0042] The powder particle agglomeration and dispersion control agent in this embodiment is the dispersant PEG600.

[0043] In this embodiment, the suspension is filtered through the first membrane assembly, the second membrane assembly, and the third membrane assembly in sequence. The slurry that does not pass through the membrane layer after filtration by the first membrane assembly, the slurry that does not pass through the membrane layer after filtration by the second membrane assembly, the slurry that does not pass through the membrane layer after filtration by the third membrane assembly, and the slurry obtained by filtration through the membrane layer by the third membrane assembly are spray dried respectively to obtain four groups of powders with different particle size distributions (N-1, S-1, S-2, S-3, S-4).

[0044] Example 3

[0045] This embodiment provides a classification method for ultrafine inorganic nanopowders, which is operated using the classification device described in Example 1, and the specific steps are as follows:

[0046] 200g zirconium oxide powder is dispersed in 5L deionized water, dispersed for 0.5h under the stirring action of 600rpm, and the suspension is heated to boiling for aging under the continuous stirring action. After being kept warm for 10h, it is cooled. After cooling to room temperature, the suspension is poured into the first bucket 1, valves 1-1, 2-1, 3-1 are opened, valve 4-1 is closed, and pump 1# is opened until the volume of the suspension in the second bucket 2 no longer increases. Then valves 1-2, 2-2, 3-2 are opened, valve 4-2 is closed, and pump 2# is opened until the volume of the suspension in the third bucket 3 no longer increases. The spray dryer is opened, valves 1-3, 2-3, 3-3 are opened, valve 4-3 is closed, pump 3# is opened, and the flow rate of the suspension entering the spray dryer is controlled by valve 3-3. The dried nano powder N-1 is collected at the receiving port below the spray dryer.

[0047] The powder particle agglomeration and dispersion control agents selected in this embodiment are PEG600 and PAA, with a mass ratio of 1:2.

[0048] Table 2

[0049]

[0050] When no more suspension flows out of the discharge pipe of valve 3-3, clean the spray dryer. Open valve 4-3, spray dry the suspension in the third barrel 3, and collect submicron powder S-2. Then spray dry the suspension in the second barrel 2 and the first barrel 1 in turn, and collect submicron powders S-3 and S-4 respectively.

[0051] In this embodiment, the suspension is filtered through the first membrane assembly, the second membrane assembly, and the third membrane assembly in sequence. The slurry that does not pass through the membrane layer after filtration by the first membrane assembly, the slurry that does not pass through the membrane layer after filtration by the second membrane assembly, the slurry that does not pass through the membrane layer after filtration by the third membrane assembly, and the slurry obtained by filtration through the membrane layer by the third membrane assembly are spray dried respectively to obtain four groups of powders with different particle size distributions (N-1, S-1, S-2, S-3, S-4).

[0052] Example 4

[0053] This embodiment provides a classification method for ultrafine inorganic nanopowders, which is operated using the classification device described in Example 1, and the specific steps are as follows:

[0054] 200g of zirconium oxide powder was dispersed in 5L of deionized water, dispersed for 0.5h under stirring at 600rpm, and dispersant PAM was added according to Table 3. Stirring was continued for 2h, and the suspension was heated to 60℃ for aging under continued stirring. After keeping warm for 10h, it was cooled. After cooling to room temperature, the suspension was poured into the first barrel 1, valves 1-1, 2-1, 3-1 were opened, valve 4-1 was closed, and pump 1# was opened until the volume of the suspension in the second barrel 2 no longer increased. Then valves 1-2, 2-2, 3-2 were opened, valve 4-2 was closed, and pump 2# was opened until the volume of the suspension in the third barrel 3 no longer increased. The spray dryer was turned on, valves 1-3, 2-3, 3-3 were opened, valve 4-3 was closed, pump 3# was opened, and the flow rate of the suspension entering the spray dryer was controlled by valve 3-3. The dried nano powder N-1 was collected at the receiving port below the spray dryer.

[0055] The powder particle agglomeration dispersion control agent in this embodiment is a dispersant PAM.

[0056] Table 3

[0057]

[0058] When no more suspension flows out of the discharge pipe of valve 3-3, clean the spray dryer. Open valve 4-3, spray dry the suspension in the third barrel 3, and collect submicron powder S-2. Then spray dry the suspension in the second barrel 2 and the first barrel 1 in turn, and collect submicron powders S-3 and S-4 respectively.

[0059] In this embodiment, the suspension is filtered through the first membrane assembly, the second membrane assembly, and the third membrane assembly in sequence. The slurry that does not pass through the membrane layer after filtration by the first membrane assembly, the slurry that does not pass through the membrane layer after filtration by the second membrane assembly, the slurry that does not pass through the membrane layer after filtration by the third membrane assembly, and the slurry obtained by filtration through the membrane layer by the third membrane assembly are spray dried respectively to obtain four groups of powders with different particle size distributions (N-1, S-1, S-2, S-3, S-4).

[0060] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for classifying ultrafine inorganic powders, characterized in that: The particle size of the ultrafine inorganic powder is below 100 nm, and the classification method comprises the following steps: S1. Add ultrafine inorganic powder to deionized water to obtain a suspension with a solid content of 10wt% to 30w%, and stir and disperse for 1 to 10 hours to obtain a dispersion; S2, adding powder particle agglomeration and dispersion regulating agent, oil bath, aging treatment for 2 to 10 hours, stirring, cooling to room temperature, filtering through at least one membrane component in turn, spray drying, to obtain at least two groups of powders with different particle size distributions; wherein the addition amount of the powder particle agglomeration and dispersion regulating agent is 0.1 to 5wt.% of the mass of the dispersion, and the oil bath temperature is 50 to 120°C.

2. The method for classifying ultrafine inorganic powder according to claim 1, characterized in that: The membrane components include three, namely a first membrane component, a second membrane component and a third membrane component, and the pore sizes of the three membrane components are different.

3. The method for classifying ultrafine inorganic powder according to claim 2, characterized in that: After cooling to room temperature, the product is filtered through the first membrane assembly, the second membrane assembly, and the third membrane assembly in sequence. The slurry that does not pass through the membrane layer after filtration by the first membrane assembly, the slurry that does not pass through the membrane layer after filtration by the second membrane assembly, the slurry that does not pass through the membrane layer after filtration by the third membrane assembly, and the slurry obtained by passing through the membrane layer after filtration by the third membrane assembly are spray dried respectively to obtain four groups of powders with different particle size distributions.

4. The method for classifying ultrafine inorganic powders according to claim 1, characterized in that: The powder particle agglomeration and dispersion regulating agent is a dispersant and / or a flocculant.

5. The method for classifying ultrafine inorganic powder according to claim 2, characterized in that: The powder particle agglomeration and dispersion control agent is at least one of PEG, PVA, PAA and PAM.

6. The method for classifying ultrafine inorganic powders according to claim 1, characterized in that: The ultrafine inorganic powder is zirconium oxide powder with a particle size of less than 100 nm, the powder particle agglomeration dispersion regulator is PEG600, the pore size of the first membrane component is 1 μm, the pore size of the second membrane component is 200 nm, and the pore size of the third membrane component is 50 nm.

7. The method for classifying ultrafine inorganic powders according to claim 1, characterized in that: The ultrafine inorganic powder is zirconium oxide powder with a particle size of less than 100 nm, the powder particle agglomeration and dispersion regulator is a mixture of PEG600 and PAA, the pore size of the first membrane component is 200 nm, the pore size of the second membrane component is 50 nm, and the pore size of the third membrane component is 10 nm.

8. The method for classifying ultrafine inorganic powders according to claim 1, characterized in that: The ultrafine inorganic powder is zirconium oxide powder with a particle size of less than 100 nm, the powder particle agglomeration dispersion regulator is PAM, the pore size of the first membrane component is 5 μm, the pore size of the second membrane component is 500 nm, and the pore size of the third membrane component is 50 nm.

9. A classification device for ultrafine inorganic powders, characterized in that: The invention comprises a membrane component and a spray dryer connected to the discharge end of the membrane component.

10. The ultrafine inorganic powder classification device according to claim 1, characterized in that: The membrane assembly is provided with three groups, namely the first membrane assembly, the second membrane assembly, and the third membrane assembly; and also includes three barrels, namely the first barrel, the second barrel, and the third barrel; The first material barrel, the first membrane assembly, the second material barrel, the second membrane assembly, the third material barrel, the third membrane assembly, and the spray dryer are connected in sequence; The spray dryer further includes a delivery pipe connected to the first material barrel, the second material barrel, and the third material barrel respectively.

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