A kind of nano talcum powder and preparation method thereof

Abstract

The present invention provides a nano-talc powder and a preparation method thereof, which relates to the technical field of mineral processing. The method comprises the following steps: S1 adding talc powder into water, adding appropriate amounts of grinding aids A and B, and dispersing by high-speed stirring to obtain a slurry; S2 pumping the prepared slurry into a bead mill for grinding until 90 <100 nm to obtain a nano-talc powder slurry; S3 filtering, drying, and dispersing the prepared nano-talc powder slurry to obtain the nano-talc powder. In the present invention, the nano-talc powder is prepared by a wet grinding technology. At the same time, a nano-oxide or nano-compound powder is used as one of the grinding aids, and the steric hindrance effect is utilized to prevent the agglomeration of the nano-talc powder, thereby solving the agglomeration problem caused by the interlayer charge adsorption of the talc flake structure during wet grinding. The prepared nano-talc powder has a particle size d 90 <100 nm, and the two-dimensional flake structure of the talc is well preserved.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing, and in particular relates to nano talcum powder and a preparation method thereof. Background Art

[0002] Based on its special physical and chemical properties and special lamellar structure, talc is widely used in ceramics, chemicals, metallurgy, papermaking, plastics, coatings, medicine, cosmetic materials and carving materials.

[0003] The crystal structure of talc allows it to be processed into fine flake particles. Such particles have a large specific surface area and good dispersibility. They are non-conductive and have good electrical insulation properties. Talc porcelain made from high-quality talc is a high-grade insulating product. Flake talc with a high diameter-to-thickness ratio also has good adsorption and covering capabilities. Combined with the excellent chemical stability of talc, it is suitable as a coating raw material to improve the fire resistance and weathering resistance of the coating.

[0004] Grinding talc to nanometer level can significantly improve the application performance of talc. The whiteness of talc will be improved after nano-grinding. As the particle size continues to decrease, the specific surface area of ​​talc will gradually increase, its surface properties will change, and the reactivity of the powder will also be significantly improved. This makes nano talc powder have higher and better performance than simply crushed talc powder when used.

[0005] Currently, talc grinding mainly adopts Raymond mill (roller mill), vertical mill or airflow mill, and most of these production processes adopt dry method. Talc itself has low hardness and is slippery. It is difficult to perform ultrafine grinding by dry grinding process, because the surface energy increases due to the decrease of talc powder particle size, and its product particle size is generally in d 90 The nanosheet structure of talc is difficult to protect using existing methods. The diameter-to-thickness ratio of talc particles after grinding is significantly reduced, and the corresponding dispersibility and adsorption are not as good as those of talc particles with a flaky structure.

[0006] Therefore, preparing a nano-talc powder that takes into account both the talc nano-sheet structure and fine particle size is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing nano talc powder. Different from the conventional Raymond mill, vertical mill or airflow mill in the prior art, the present invention adopts a wet grinding process to prepare nano talc powder, which can preserve the nano flaky structure of talc to the greatest extent. Further, the present invention innovatively uses nano oxide or nano compound powder as a grinding aid, and utilizes the steric hindrance effect to prevent the agglomeration of nano talc powder, thereby reducing the large amount of energy consumption caused by the agglomeration phenomenon in the processing process, and also makes the nano talc powder smaller in particle size and has higher reactivity.

[0008] To achieve the above object, the present invention provides a method for preparing nano talc, which specifically comprises the following steps:

[0009] S1: adding talcum powder to a certain amount of water, and adding appropriate amounts of grinding aid A and grinding aid B, stirring and dispersing at high speed to obtain a slurry;

[0010] S2: The slurry prepared in step S1 is pumped into a bead mill for grinding until d 90 <100nm, nano-scale talc slurry is obtained;

[0011] S3: Filter, dry and break up the nano-scale talc slurry prepared in step S2 to obtain nano-talc.

[0012] In a preferred embodiment, in step S1, the talc content in the talc powder is ≥50% and the content of impurity minerals with Mohs hardness >7 is <5%, and the talc powder d 75 <10μm.

[0013] In a preferred embodiment, in step S1, the grinding aid A includes one or more of sodium polyacrylate, triethanolamine, and sodium hexametaphosphate.

[0014] In a preferred embodiment, in step S1, the grinding aid B includes one or more of nano-titanium dioxide, nano-silicon dioxide, nano-aluminum oxide, and nano-calcium carbonate.

[0015] In a preferred embodiment, in step S1, the grinding aid B powder has a d 90 <80nm and d max <1μm.

[0016] In a preferred embodiment, in step S1, the mass ratio of talcum powder, water, grinding aid A and grinding aid B is 100:(150-1000):(0.5-5):(0.1-5).

[0017] In a preferred embodiment, in step S1, the high-speed stirring and dispersing speed is 600-2500 rpm.

[0018] In a preferred embodiment, in step S2, in the grinding step, the grinding medium used includes one of zirconia ceramic beads, diamonds or alumina ceramic beads, the grinding medium size is φ0.08-0.4 mm, and the filling rate of the grinding medium in the grinding cavity is 65%-80%.

[0019] Another object of the present invention is to provide a nano talc powder prepared by any one of the above methods, wherein the nano talc powder is 90<100nm and the two-dimensional lamellar structure of talc is well preserved.

[0020] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0021] 1. The present invention innovatively uses a wet grinding process to successfully prepare nano talc powder. Since talc is soft and slippery in nature, the present invention further innovatively uses nano oxide powder as a grinding aid, and utilizes the steric hindrance effect to disperse the talc flakes, thereby solving the agglomeration problem caused by interlayer charge adsorption of the talc flake structure during wet grinding of talc. Compared with the general talc wet grinding process and dry process (air flow mill, roller mill), this method has the advantages of fine product particle size, environmentally friendly process, and easy industrialization, and can preserve the high diameter-to-thickness ratio nano-flaky structure of talc, and can have better performance in application scenarios such as insulating materials, lubricants, coatings, and bioceramic materials.

[0022] 2. The process flow of the method of the present invention is simple. Nano talc slurry can be obtained by breaking up and nano-grinding, and then drying and breaking up to obtain nano talc. The preparation process is efficient, has no special requirements for processing equipment, has low energy consumption and low cost, and is particularly suitable for large-scale industrial production.

[0023] 3. The talc used in the method of the present invention includes both conventional talc powder and black talc powder, which can form a resource development and utilization approach for black talc, which has limited application in the prior art, and expand its application field. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] These and / or other aspects and advantages of the present invention will become more clear and easier to understand from the following detailed description of the embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0025] Figure 1 This is a scanning electron microscope image of the talcum powder raw material in Example 1 of the present invention.

[0026] Figure 2 This is a scanning electron microscope image of the nano talc sample prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods, but it should be understood that the protection scope of the present invention is not limited to the specific implementation methods.

[0028] The embodiment of the present invention provides a nano talc powder and a preparation method thereof, thereby solving the problem that it is difficult to obtain a talc nano sheet structure and particle size in a conventional method in the prior art.

[0029] The technical solution in the present invention is to solve the above problems, and the overall idea is as follows:

[0030] The present invention provides a method for preparing nano talc, which specifically comprises the following steps:

[0031] S1: adding talcum powder to a certain amount of water, and adding appropriate amounts of grinding aid A and grinding aid B, stirring and dispersing at high speed to obtain a slurry;

[0032] S2: The slurry prepared in step S1 is pumped into a bead mill for grinding until d 90 <100nm, nano-scale talc slurry is obtained;

[0033] S3: Filter, dry and break up the nano-scale talc slurry prepared in step S2 to obtain nano-talc.

[0034] In a preferred embodiment, in step S1, the talc content in the talc powder is ≥50% and the content of impurity minerals with Mohs hardness >7 is <5%, and the talc powder d 75 <10μm.

[0035] In a preferred embodiment, in step S1, the grinding aid A includes one or more of sodium polyacrylate, triethanolamine, and sodium hexametaphosphate. Preferably, the grinding aid A is sodium polyacrylate.

[0036] In a preferred embodiment, in step S1, the grinding aid B includes one or more of nano-titanium dioxide, nano-silicon dioxide, nano-aluminum oxide, and nano-calcium carbonate. Preferably, the grinding aid B is nano-titanium dioxide.

[0037] In a preferred embodiment, in step S1, the grinding aid B powder has a d 90 <80nm and d max <1μm.

[0038] In a preferred embodiment, in step S1, the mass ratio of talcum powder, water, grinding aid A and grinding aid B is 100: (150-1000): (0.5-5): (0.1-5), preferably, the mass ratio of talcum powder, water, grinding aid A and grinding aid B is 100: (200-300): (1.5-2): (0.5-1).

[0039] In a preferred embodiment, in step S1, the high-speed stirring and dispersing rotation speed is 600-2500 rpm, preferably, the high-speed stirring and dispersing rotation speed is 1200-1600 rpm.

[0040] In a preferred embodiment, in step S1, the high-speed stirring and dispersing time is 0.5-4 h, preferably, the high-speed stirring and dispersing time is 1-2 h.

[0041] In a preferred embodiment, in step S2, in the grinding step, the grinding medium used includes one of zirconia ceramic beads, diamonds or alumina ceramic beads, the grinding medium size is φ0.08-0.4mm, and the filling rate of the grinding medium in the grinding chamber is 65%-80%. Preferably, the grinding medium size is φ0.08mm-0.3mm, and the filling rate is 70%-80%.

[0042] In the present invention, the size and filling rate of the grinding medium are controlled so as to perform ultrafine grinding on the talc powder, thereby obtaining nano-scale particles and preserving the nano-flaky structure of the talc to the greatest extent.

[0043] In a preferred embodiment, in step S3, the filtering, drying and breaking up can be carried out in conventional ways known to those skilled in the art, as long as the operation purpose can be achieved. Preferably, the drying method is drying at 80-150°C.

[0044] Another object of the present invention is to provide a nano talc powder prepared by any one of the above methods, wherein the nano talc powder is 90 <100nm and the two-dimensional lamellar structure of talc is well preserved.

[0045] The technical solution of the present application is described in detail below through specific embodiments:

[0046] Unless otherwise specified, the technical means used in the present invention are conventional means well known to those skilled in the art, and the various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. The reagents used in the present invention are analytically pure unless otherwise specified.

[0047] In the embodiments of the present invention, the talc powder used is black talc powder produced in Guangfeng District, Shangrao City, Jiangxi Province, wherein the talc content in the black talc powder is ≥50% and the content of impurity minerals with Mohs hardness >7 is <5%.

[0048] Example 1

[0049] This embodiment provides a method for preparing nano talcum powder, comprising the following steps:

[0050] 1) talcum powder (talcum powder particle size distribution d 90 =8.30μm) was added to a certain amount of water, and sodium polyacrylate and nano-titanium dioxide were added as grinding aids, with a ratio of talcum powder: water: sodium polyacrylate: nano-titanium dioxide = 100: 200: 1: 0.3. The mixture was dispersed in a high-speed stirring disperser at 1400rpm for 4h.

[0051] 2) Add diamond grinding media with a diameter of φ0.08 mm into the nano bead mill with a filling rate of 80%, and then pump the slurry prepared in step 1) into the bead mill storage tank.

[0052] 3) Grind the material repeatedly in a bead mill. After 30 times of grinding, pump out the slurry, dry it, and break it up to obtain a nano talc powder sample. Detect the talc particle size distribution. 90 =0.064 μm. The prepared nano talc powder sample is as follows Figure 2 As shown in the figure, it can be seen that compared with the talcum powder raw material ( Figure 1 ), the technical solution provided by the present invention can preserve the two-dimensional lamellar structure of talcum powder samples intact.

[0053] Example 2

[0054] This embodiment provides a method for preparing nano talcum powder, comprising the following steps:

[0055] 1) talcum powder (talcum powder particle size distribution d 90 =6.25μm) was added to a certain amount of water, and sodium hexametaphosphate and nano-silicon dioxide were added as grinding aids, with a ratio of talcum powder: water: sodium hexametaphosphate: nano-silicon dioxide = 100: 300: 4: 0.8. The mixture was dispersed in a high-speed stirring disperser at 800rpm for 2.5h.

[0056] 2) Add zirconium oxide grinding media with a diameter of φ0.1 mm into the nano bead mill with a filling rate of 70%, and then pump the slurry prepared in 1) into the bead mill storage tank.

[0057] 3) Grind the material repeatedly in a bead mill. After 35 times of grinding, pump out the slurry, dry it, and break it up to obtain a nano talc powder sample. Detect the talc particle size distribution. 90 =0.076μm.

[0058] Example 3

[0059] This embodiment provides a method for preparing nano talcum powder, comprising the following steps:

[0060] 1) black talcum powder (talc particle size distribution d 90 =9.7μm, d 50 =1.4μm) was added to a certain amount of water, and triethanolamine and nano-alumina were added as grinding aids, with a ratio of black talcum powder: water: triethanolamine: nano-alumina = 100:250:2:0.5. The mixture was dispersed in a high-speed stirring disperser at 2000rpm for 1.5h.

[0061] 2) Add zirconia grinding media with a diameter of 0.4 mm into the nano bead mill with a filling rate of 65%, and then pump the slurry prepared in 1) into the bead mill storage tank.

[0062] 3) Grind the material repeatedly in a bead mill, pump out the slurry after 30 times of grinding, dry and break it up to obtain a nano black talc sample, and detect the talc particle size distribution d 90 =0.095μm.

[0063] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for preparing nano talcum powder, characterized in that: The specific steps include: S1: adding talcum powder to a certain amount of water, and adding appropriate amounts of grinding aid A and grinding aid B, stirring and dispersing at high speed to obtain a slurry; S2: pumping the slurry prepared in step S1 into a bead mill for grinding until d90 < 100 nm to obtain nano-grade talc slurry; S3: filtering, drying and breaking up the nano-grade talc slurry prepared in step S2 to obtain nano-talc; In step S1, the talc content in the talc powder is ≥50% and the content of impurity minerals with Mohs hardness>7 is <5%, and the talc powder d75 is <10 μm; In step S1, the grinding aid B includes one or more of nano titanium dioxide, nano silicon dioxide, nano aluminum oxide, and nano calcium carbonate; the grinding aid B powder has a d90 < 80 nm and a dmax < 1 μm; In step S2, in the grinding step, the grinding medium used includes one of zirconia ceramic beads, diamonds or alumina ceramic beads, the size of the grinding medium is φ0.08-0.4 mm, and the filling rate of the grinding medium in the grinding cavity is 65%-80%.

2. The method for preparing nano talcum powder as claimed in claim 1, characterized in that, In step S1, the grinding aid A includes one or more of sodium polyacrylate, triethanolamine, and sodium hexametaphosphate.

3. The method for preparing nano talc according to claim 1, wherein In step S1, the mass ratio of talcum powder, water, grinding aid A and grinding aid B is 100:(150-1000):(0.5-5):(0.1-5).

4. The method for preparing nano talc according to claim 1, wherein In step S1, the high-speed stirring and dispersing speed is 600-2500 rpm.

5. The nano talc powder prepared by the method according to any one of claims 1 to 4.

6. The nano talc powder according to claim 5, characterized in that The nano talc powder has a d90 value less than 100 nm and the two-dimensional lamella structure of the talc is well preserved.

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