Integrated preparation process of nano montmorillonite

Abstract

The invention discloses an integrated process for preparing nano montmorillonite, which comprises the following steps of: firstly, uniformly mixing bentonite and water, and pulping after sequentially carrying out sealing aging and roller alignment; then, a three-stage series hydrocyclone group is adopted for desanding, settling separation and three-roller grinding are combined, and efficient enrichment of montmorillonite is achieved; lamellas of the montmorillonite are stripped through ultrasonic treatment, high-pressure homogenization and the synergistic effect of the ultrasonic treatment, the high-pressure homogenization and the synergistic effect, and then a nano montmorillonite product is obtained through filter pressing and drying. According to the technology, based on the swelling characteristic, the layered structure and the unique sedimentation behavior of bentonite, the coupling mechanical force, the hydraulic cyclone, the cavitation effect, the gravity separation and other effects, efficient wet stripping of montmorillonite lamellas is achieved, and the problems of structural damage, low single-layer rate, insufficient yield and the like in the nanocrystallization process are effectively solved; and a key nano material is provided for fully exerting the structural advantages of the bentonite and improving the application performance of the bentonite.

Description

Technical Field

[0001] This invention relates to a clay mineral nano-processing technology, specifically to an integrated preparation process for nano-montmorillonite. Background Technology

[0002] Clay mineral nanofiberization refers to the process of treating natural clay minerals (such as montmorillonite, kaolinite, attapulgite, etc.) into materials with a nanoscale (1-100 nm) at least in one dimension through physical or chemical methods. This process can significantly enhance the ion exchange capacity, chemical modification potential (such as organic modification), and selective adsorption performance of clay minerals, while effectively improving their interfacial compatibility and dispersion stability in composite systems. Therefore, nanofiberization is a key foundation for fully leveraging the structural advantages of clay minerals and achieving performance leaps. Furthermore, nanofiberization not only helps transform abundant and inexpensive natural clay resources into high-value-added functional materials, but also enables the targeted design and precise construction of material functions through fine-tuning of their physicochemical properties to meet the specific needs of high-end applications. Currently, nano-clay minerals have been widely used in cutting-edge fields such as high-performance nanocomposites, environmental pollution control, new energy and energy storage, biomedicine, and intelligent catalysis. In conclusion, clay mineral nanofiberization is an important bridge connecting traditional mineral resources and advanced nanotechnology, becoming a core approach to improving material performance and expanding new application directions, possessing significant scientific research value and broad engineering application prospects.

[0003] Bentonite is a non-metallic mineral with montmorillonite (a 2:1 type layered aluminosilicate clay mineral) as its main component. It possesses high cation exchange capacity, large specific surface area, and excellent binding and colloidal properties, making it widely used in daily chemicals, pharmaceuticals, casting, drilling, environmental protection, and building materials. Exfoliating the montmorillonite component into single-layer or few-layer nanosheets and achieving large-scale preparation of nano-montmorillonite is of significant practical importance in promoting the transformation of bentonite from a traditional mineral to a high-value-added advanced functional material, thus stimulating the development of various exfoliation methods. Currently, the main methods include mechanical exfoliation and chemical intercalation. Mechanical exfoliation methods (such as ball milling, high-speed stirring, and roller extrusion) rely on physical actions such as shearing and extrusion to separate the layers. While they have advantages such as large throughput and low cost, they are usually difficult to achieve a high monolayer ratio and easily damage the mineral's nanostructure, reducing its performance. Chemical intercalation exfoliation, by inserting intercalating agents such as quaternary ammonium salts and polymers to expand interlayer spacing and weaken interlayer forces, can achieve a high monolayer ratio while maintaining structural integrity. However, it suffers from problems such as complex processes, low product yields, and the need for chemical processing and subsequent purification. Therefore, developing an integrated process for the efficient preparation of nano-montmorillonite based on the structural characteristics and mineral properties of bentonite has become an urgent research need. Summary of the Invention

[0004] To address the common problems in current bentonite exfoliation and nanostructuring techniques, such as nanostructure damage, chemical residues, and low monolayer yield and single-layer ratio under large-scale production conditions, this invention proposes a novel multi-field coupled bentonite nanostructuring process integrating mechanical force, gravitational field, and cavitation field. This process aims to achieve efficient and non-destructive exfoliation of montmorillonite layers, providing a feasible route for the preparation of high-quality montmorillonite nanomaterials and potentially extending to the nanostructuring applications of other clay minerals. Currently, such multi-field coupled exfoliation methods have not been reported or practically applied domestically or internationally, demonstrating significant innovative potential and application prospects.

[0005] In the integrated nano-montmorillonite preparation process proposed in this invention, the bentonite raw material is first pretreated by wet roller crushing and cyclone sand removal. Then, under the synergistic effect of multiple fields including mechanical force, ultrasonic cavitation, high-pressure homogenization, and gravity, the montmorillonite sheets are efficiently exfoliated. Finally, montmorillonite nanosheets are obtained through pressure filtration and enhanced drying. The specific steps are as follows: (1) Bentonite pretreatment: Bentonite and water are mixed evenly in a powder-liquid mixer at a mass ratio of 3:1, sealed and aged for 24 hours, and then conveyed to a roller press to press into thin sheets with a thickness of 1-2 mm; then the thin sheets are sent to a pulping equipment, water is added to make a slurry with a bentonite mass fraction of 10-15%, and the mixture is stirred continuously for 8-12 hours. During the 24-hour sealed aging process in water, water molecules gradually penetrate into the interlayer domains of montmorillonite, promoting the full expansion and separation of the crystal layers. Subsequent roller processing applies mechanical compaction to the bentonite, utilizing high-intensity shear and pressure to further peel away the montmorillonite crystal layers, disrupting the interlayer bonding and increasing its specific surface area. The roller processing parameters are set as follows: the speed ratio of the front and rear rollers is controlled between 1:1.2 and 1:1.4; the material undergoes 2-4 passes of rolling, with the roll gap decreasing by 0.5 mm per pass, resulting in a final rolling thickness of 1 mm. The speed difference between the two rollers creates a velocity gradient in the roll gap area, subjecting the bentonite to significant shearing, tearing, and compressive forces as it passes through; multiple roller passes also contribute to the uniformity of material composition and properties; precise control of the speed ratio and number of rolling passes aims to protect the montmorillonite lamellae structure from damage during the peeling process. After aging and roller treatment, the bentonite particles are smaller, the specific surface area is larger, and the distribution is more uniform, which significantly accelerates the stirring and hydration process. Continuous stirring for 8 to 12 hours can achieve full hydration and dispersion of bentonite.

[0006] (2) Cyclone grading and purification: The slurry obtained in step (1) is pumped into a first-stage hydrocyclone, the first-stage overflow enters a second-stage hydrocyclone, the second-stage overflow returns to the first-stage inlet, and after being circulated 2 to 3 times, it is sent to step (3) for layer stripping; the first-stage underflow and the second-stage underflow enter a third-stage hydrocyclone, the third-stage overflow is sent to a settling tank for static separation, and the third-stage underflow is discharged from the system; the mass ratio of the overflow to the underflow of the hydrocyclone is controlled at 7:3 to 8:2; the clear liquid in the upper layer of the settling tank is reused for pulping, and the lower layer of sediment is returned to the pulping process in step (1) after being ground by three rollers; This invention employs a three-stage hydrocyclone configuration in series, combined with sedimentation and three-roll milling processes, to achieve efficient separation and enrichment of lamellar montmorillonite. The first-stage hydrocyclone consists of 4-6 hydrocyclones connected in parallel, each with an inner diameter of 75 mm and a cone angle of 6°, operating at a pressure of 0.3 MPa. The second-stage hydrocyclone consists of 6-8 hydrocyclones connected in parallel, each with an inner diameter of 50 mm and a cone angle of 6°, operating at a pressure of 0.2 MPa. The third-stage hydrocyclone consists of 8-10 hydrocyclones connected in parallel, each with an inner diameter of 25 mm and a cone angle of 6°, operating at a pressure of 0.2 MPa. Lamellar particles experience significant shape resistance during sedimentation in the fluid, especially when the plane of the lamellar particles is perpendicular to the sedimentation direction. Under the turbulence and shearing action within the hydrocyclone, the lamellar particles continuously tumble and reorient, resulting in an average sedimentation velocity far lower than that of spherical particles of the same size and density. Therefore, the settling behavior of larger flake particles can be equivalent to that of smaller spherical particles, enabling the hydrocyclone to preferentially enrich flake minerals (regardless of particle size) into the overflow, while discharging equiaxed gangue minerals (such as quartz and feldspar) of similar particle size into the underflow, thus achieving shape-selective grading. Based on the unique settling behavior of flake particles and the excellent selective grading and purification capability of the hydrocyclone for flake minerals, this invention achieves efficient separation and enrichment of flake montmorillonite by using a two-stage hydrocyclone circulation process 2-3 times, which is then sent to the flake stripping process (3).

[0007] Furthermore, the underflow from the first and second stage hydrocyclones is fed into a third-stage hydrocyclone for further classification. Its small diameter and cone angle design facilitates high-precision separation of minerals and quartz sand. Residual minerals from the first and second stage underflows are effectively enriched in the third-stage overflow, which is then sent to a settling tank with a height-to-diameter ratio (H / D) of 4:1 to 5:1 for static separation. This high H / D ratio promotes rapid mineral settling. The tank is equipped with an ultrasonic interface meter to monitor the mineral phase interface height in real time. Solid-liquid separation is considered complete when the interface settling rate drops below 2% / h of the tank height. Subsequently, the supernatant (water) from the settling tank is reused for pulping, while the lower settling minerals are returned to the pulping step after three-roll milling. The three-roll milling process parameters are: the speed ratio of the rear roller, middle roller, and front roller is controlled at 1:2.5:7 to 1:3:9; the roller gap between the rear roller and middle roller is 50–100 μm, and the roller gap between the middle roller and front roller is 15–20 μm; the number of grinding cycles is 2–4. The three-roll differential process strips or disperses granular minerals or quartz sand-encapsulated minerals from the sediment before returning it to the pulping tank, ensuring efficient enrichment of mineral components (enrichment rate ≥90%) and high yield of nano-sized products.

[0008] (3) Delamination and post-treatment: The purified slurry obtained in step (2) is fed into the delamination unit, and the montmorillonite lamellae are delaminated using ultrasonic delamination, high-pressure homogenization delamination, or ultrasonic-high-pressure homogenization synergistic delamination. The delaminated slurry is then pressure filtered, and the resulting filter cake is subjected to high-pressure drying to obtain nano-montmorillonite. The power density of ultrasonic delamination is 100-200 W / L, the frequency is 20-40 kHz, and the processing time is 8-12 min. The pressure of high-pressure homogenization delamination is 30-60 MPa. Moreover, ultrasonic delamination, high-pressure homogenization delamination, or their synergistic delamination can be repeated or cyclically performed. The pressure filtration adopts plate and frame filtration or high-pressure diaphragm filtration, with a feed pressure of 1.6-2.5 MPa, and the resulting filter cake has a moisture content of 30%-40%. High-pressure drying is carried out at a drying temperature of 90-100℃ and a grading frequency of 5-25 Hz.

[0009] The results of the embodiments of the present invention confirm that the microstructure of bentonite (Bent) exhibits a multi-layered disordered stacked structure, while the TEM image of the nano-montmorillonite prepared by the process of the present invention ( Figure 2 The results showed a significant reduction in the stacking of montmorillonite lamellae, with the emergence of numerous independent lamellae, confirming that a strong cavitation effect acts on the interlamellae, effectively achieving the exfoliation of montmorillonite lamellae. Bentonite and nano-montmorillonite were separately dispersed in water (solid content 2%), stirred at 11000 rpm for 20 minutes, and then placed in a 100 ml graduated cylinder. The change in the volume of the suspension over time was recorded. Figure 3As shown, the volume of the bentonite slurry suspension decreased significantly to 13 mL after standing for 1 hour, and a clear phase separation interface appeared after 3 hours; while the nano-montmorillonite slurry showed excellent suspension stability, and only slight sedimentation occurred after standing for 3 days, indicating that it has good application potential in drilling mud, coatings and thixotropic agents.

[0010] XRD spectrum ( Figure 4 a) The results show that, compared to the raw bentonite, the (001) crystal plane diffraction peak of nano-montmorillonite shifts to a lower angle, and the interlayer spacing increases, further confirming the exfoliation of montmorillonite lamellae. Additionally, albite (27.7... o ) and quartz (26.56) o The diffraction peak intensity of the FTIR spectrum decreased significantly, indicating that denser impurity minerals were effectively removed by the hydrocyclone. Figure 4 (b) No new absorption peaks appeared, indicating that the nano-sizing treatment did not alter the layered structure and crystal integrity of montmorillonite. Chemical composition analysis (Table 1) shows that the contents of framework elements such as SiO2, Al2O3, Fe2O3, MgO, CaO, and K2O remained basically stable, while the contents of Na2O and SO3 decreased, possibly related to feldspar separation or sulfate dissolution. Specific surface area and pore size distribution results ( Figure 5 Table 2 shows that the specific surface area of ​​nano-montmorillonite increases to 1.4-1.8 times that of bentonite, and the pore volume also increases significantly. This indicates that its structure has changed from tightly stacked multilayers to fewer layers or single overlapping layers, forming a certain number of packed pores. This nanosheet structure, high specific surface area, and excellent dispersibility make nano-montmorillonite significantly superior to bentonite in applications such as wastewater treatment, environmental remediation, catalysis, and polymer composites, and the added value of the corresponding products is also greatly improved.

[0011] In summary, the present invention has the following advantages compared with the prior art: 1. This invention proposes an integrated preparation process for nano-montmorillonite. First, bentonite raw materials undergo hydrated, sealed aging, differential-speed roller mixing, and slurry preparation to fully hydrate and expand the bentonite, weakening the interlayer bonding forces. Then, a three-stage hydraulic cyclone process is used to achieve efficient separation and enrichment of the montmorillonite layers. Finally, ultrasonic waves, high-pressure homogenization, and their synergistic effects are combined to achieve efficient exfoliation of the montmorillonite layers. This innovative process integrates cavitation fields, mechanical forces, and gravitational fields, providing a feasible approach for the controllable preparation and large-scale production of high-quality montmorillonite nanomaterials.

[0012] 2. Based on the unique settling behavior of lamellar minerals and the selective classification capability of hydrocyclones, this invention employs a two-stage circulating hydrocyclone to achieve high-precision separation and enrichment of lamellar montmorillonite, followed by delamination. Minerals remaining in the underflow of the first and second stage hydrocyclones are further enriched by a third stage hydrocyclone. After settling and stratification, the remaining minerals are dispersed by a three-roll mill and returned to the pulping tank. This strategy of circulating classification combined with wet grinding significantly improves the enrichment efficiency of montmorillonite, effectively reduces mineral loss, and thus ensures high purity and high yield of the nano-montmorillonite product.

[0013] 3. This invention uses abundant and environmentally friendly bentonite as raw material, and achieves the nano-sizing of montmorillonite through ultrasonic cavitation, high-pressure homogenization, and their combined cyclic exfoliation without introducing chemical reagents. This process can be flexibly adjusted according to needs to produce montmorillonite powders of different nano-scale degrees in batches. It is suitable for high-value-added fields such as wastewater treatment, environmental remediation, catalysis, and polymer composites, meeting the needs of various high-end application scenarios and providing important technical support for the transformation of clay minerals into high-value-added functional materials and the development of advanced nanomaterials. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the integrated preparation process of nano-montmorillonite according to the present invention. In the diagram, 1-powder-liquid mixer, 2-roll mill, 3-slurry preparation equipment, 4-first-stage hydrocyclone, 5-second-stage hydrocyclone, 6-third-stage hydrocyclone group, 7-sedimentation tank group, 8-three-roll mill, 9-ultrasonic peeling equipment, 10-high-pressure homogenizer, 11-one-way valve, 12-high viscosity pump, 13-plate and frame filter press, 14-high-intensity drying equipment.

[0015] Figure 2 These are TEM images of bentonite and nano-montmorillonite prepared using the process of this invention.

[0016] Figure 3 These are digital photographs showing the change in stability of the suspensions of bentonite and nano-montmorillonite prepared by the process of this invention over time. From left to right, the slurries are Bent, NanoMent-U-1, NanoMent-U-2, NanoMent-H-1, NanoMent-H-2, and NanoMent-UH.

[0017] Figure 4 The images show the XRD (a) and FTIR spectra (b) of bentonite and nano-montmorillonite prepared by the process of this invention.

[0018] Figure 5 The images show the adsorption / desorption isotherms (a) and pore size distribution curves (b) of bentonite and nano-montmorillonite prepared by the process of this invention. Detailed Implementation

[0019] The integrated preparation process of nano-montmorillonite and the properties of nano-montmorillonite of the present invention will be further explained below through typical embodiments.

[0020] Comparative Example 1 75 kg of bentonite and 25 kg of water were added to a powder-liquid mixer and mixed evenly. After being sealed and aged for 24 hours, the mixture was conveyed to a roller mill for rolling. The front and rear roller speed ratio of the roller mill was 1:1.4, and the material was rolled into a sheet with a thickness of 1 mm in two passes. The sheet was then transferred to a pulping device, where water was added to prepare a slurry with a bentonite mass fraction of 10%, and the mixture was continuously stirred for 12 hours. The resulting slurry was filtered through a plate and frame filter press at a feed pressure of 1.6 MPa to obtain a filter cake, which was then subjected to high-pressure drying at 100 °C to finally obtain the bentonite powder product, denoted as Bent.

[0021] Example 1 The integrated process for preparing nano-montmorillonite according to the present invention comprises the following steps: (1) Mix 75 kg of bentonite with 25 kg of water in a powder-liquid mixer until homogeneous, and seal and age for 24 hours. Then, convey the material to a roller mill for rolling, with a front-to-back roller speed ratio of 1:1.2, and roll it into a sheet with a thickness of 1 mm after 4 passes. Transfer the sheet to a pulping equipment, add water to make a slurry with a bentonite mass fraction of 15%, and continue stirring for 8 hours to obtain a bentonite slurry; (2) Pump the bentonite slurry obtained in step (1) into the first-stage hydrocyclone at an operating pressure of 0.3 MPa. The first-stage overflow enters the second-stage hydrocyclone, and the second-stage overflow is sent to the lamellae stripping process (3). The first-stage and second-stage underflows enter the third-stage hydrocyclone, and the third-stage overflow is sent to a settling tank with a height-to-diameter ratio of 4:1 for static separation. The third-stage underflow is discharged from the system. The inner diameters of the cylinders of the first, second, and third-stage hydrocyclones are 75 mm, 50 mm, and 25 mm, respectively, and the cone angle is 6°. The mass ratio of the overflow to the underflow of the hydrocyclone is controlled at 7:3. The clear liquid in the upper layer of the settling tank is reused for pulping, and the lower layer of sediment is returned to the pulping process after being ground by three rollers. The three-roll grinding parameters are: the speed ratio of the rear roller, the middle roller, and the front roller is controlled at 1:3:9; the roller gap between the rear roller and the middle roller is 50 μm, and the roller gap between the middle roller and the front roller is 15 μm; the material is ground twice. (3) The purified slurry obtained in step (2) was subjected to ultrasonic treatment to achieve the exfoliation of montmorillonite flakes. The ultrasonic power density was 200 W / L, the frequency was 20 kHz, and the treatment time was 8 min. After ultrasonic treatment, the slurry was filtered by high-pressure diaphragm at a feed pressure of 2.5 MPa to obtain filter cake, and then subjected to strong drying at 90℃ to finally obtain nano-montmorillonite powder product, denoted as NanoMont-U-1. Example 2 The integrated process for preparing nano-montmorillonite according to the present invention comprises the following steps: Example 1 was repeated, except that: (3) the purified slurry obtained in step (2) was subjected to ultrasonic treatment to achieve the exfoliation of montmorillonite sheets. The ultrasonic power density was 100 W / L, the frequency was 20 kHz, and the treatment time was 12 min. Finally, nano-montmorillonite powder product was obtained, denoted as NanoMont-U-2.

[0022] Example 3 The integrated process for preparing nano-montmorillonite according to the present invention comprises the following steps: (1) Mix 75 kg of bentonite with 25 kg of water in a powder-liquid mixer until homogeneous, and seal and age for 24 hours. Then, convey the material to a roller mill for rolling, with a front-to-back roller speed ratio of 1:1.4, and roll it into a sheet with a thickness of 1 mm after two passes. Transfer the sheet to a pulping equipment, add water to prepare a slurry with a bentonite mass fraction of 15%, and continue stirring for 12 hours to obtain a bentonite slurry; (2) The bentonite slurry obtained in step (1) is pumped into a primary hydrocyclone (75 mm inner diameter, 6° cone angle) at an operating pressure of 0.3 MPa. The primary overflow enters a secondary hydrocyclone (50 mm inner diameter, 6° cone angle), and the secondary overflow returns to the inlet of the primary hydrocyclone. After two cycles of circulation, the slurry is sent to the lamellae stripping process (3). The primary and secondary underflows are combined and sent to a tertiary hydrocyclone (25 mm inner diameter, 6° cone angle). The tertiary overflow is sent to a settling tank with a height-to-diameter ratio of 5:1 for static separation, while the tertiary underflow is discharged from the system. The mass ratio of overflow to underflow in each hydrocyclone is controlled at 8:2. The clear liquid in the upper layer of the settling tank is reused for pulping, and the lower layer of sediment is returned to the pulping process after being ground by three rollers (the speed ratio of the rear roller, middle roller, and front roller is 1:2.5:7, the gap between the rear roller and the middle roller is 100 μm, the gap between the middle roller and the front roller is 20 μm, and the grinding is carried out 4 times). (3) The purified slurry obtained in step (2) is subjected to high-pressure homogenization at 30 MPa to achieve the peeling of montmorillonite flakes. The homogenized slurry is then filtered through a high-pressure diaphragm at a feed pressure of 2.5 MPa to obtain a filter cake, which is then subjected to strong drying at 100°C to finally obtain nano-montmorillonite powder product, denoted as NanoMont-H-1.

[0023] Example 4 The integrated process for preparing nano-montmorillonite according to the present invention comprises the following steps: Example 3 was repeated, except that: (3) the purified slurry obtained in step (2) was subjected to high-pressure homogenization at 60 MPa to achieve the exfoliation of montmorillonite flakes. Finally, nano-montmorillonite powder product was obtained, denoted as NanoMont-H-2.

[0024] Example 5 The integrated process for preparing nano-montmorillonite according to the present invention comprises the following steps: (1) Mix 75 kg of bentonite with 25 kg of water in a powder-liquid mixer until homogeneous, and seal and age for 24 hours. Then, convey the material to a roller mill for rolling, with a front-to-back roller speed ratio of 1:1.2, and roll it into a sheet with a thickness of 1 mm after two passes. Transfer the sheet to a pulping equipment, add water to prepare a slurry with a bentonite mass fraction of 10%, and continue stirring for 12 hours to obtain a bentonite slurry; (2) The bentonite slurry obtained in step (1) is pumped into a primary hydrocyclone (75 mm inner diameter, 6° cone angle) at an operating pressure of 0.3 MPa. The primary overflow enters a secondary hydrocyclone (50 mm inner diameter, 6° cone angle), and the secondary overflow returns to the inlet of the primary hydrocyclone. After being circulated twice, it is sent to the lamellae stripping process (3). The primary and secondary underflows are combined and enter a tertiary hydrocyclone (25 mm inner diameter, 6° cone angle). The tertiary overflow is sent to a settling tank with a height-to-diameter ratio of 4:1 for static separation, and the tertiary underflow is discharged from the system. The mass ratio of overflow to underflow of each hydrocyclone is controlled at 7:3. The clear liquid in the upper layer of the settling tank is reused for pulping, and the lower sediment is ground by three rollers (the speed ratio of the rear roller, middle roller, and front roller is 1:3:9, the gap between the rear roller and the middle roller is 50 μm, the gap between the middle roller and the front roller is 20 μm, and the grinding is repeated twice) and then returned to the pulping process. (3) The purified slurry obtained in step (2) was subjected to ultrasonic and high-pressure homogenization to achieve montmorillonite lamellae exfoliation. The ultrasonic power density was 200 W / L, the frequency was 20 kHz, and the treatment time was 8 min. The ultrasonically treated slurry was further subjected to high-pressure homogenization at 30 MPa to achieve montmorillonite lamellae exfoliation. The homogenized slurry was filtered through a high-pressure diaphragm at a feed pressure of 2.5 MPa to obtain a filter cake, which was then subjected to strong drying at 100℃ to finally obtain nano-montmorillonite powder product, denoted as NanoMont-UH.

Claims

1. A process for the integrated preparation of nanomontmorillonite, characterized by, The method comprises the following steps: (1) Pretreatment: uniformly mix bentonite and water according to a mass ratio of 3:1, seal and age for 24 hours, press into 1-2 mm thick sheets through a roller mill, add water to prepare a slurry with a mass fraction of 10-15%, and continuously stir for 8-12 hours; (2) Cyclone classification and purification: pump the slurry obtained in step (1) into a first-stage hydrocyclone, the overflow of the first-stage hydrocyclone is introduced into a second-stage hydrocyclone, the overflow of the second-stage hydrocyclone is returned to the inlet of the first-stage hydrocyclone, and after 2-3 cycles of circulation treatment, the slurry is sent to step (3) for sheet layer peeling; the underflow of the first-stage hydrocyclone and the underflow of the second-stage hydrocyclone are introduced into a third-stage hydrocyclone, the overflow of the third-stage hydrocyclone is introduced into a settling tank for separation, and the underflow of the third-stage hydrocyclone is discharged from the system; the mass ratio of the overflow to the underflow of the hydrocyclone is controlled to be 7:3-8:2; the supernatant of the settling tank is recycled for slurry preparation, and the sediment at the bottom of the settling tank is ground through a three-roller mill and then returned to the slurry preparation process in step (1); (3) Sheet layer peeling and post-treatment: the purified slurry obtained in step (2) is subjected to ultrasonic peeling, high-pressure homogenization peeling or a combination thereof to peel off the sheet layer of the montmorillonite, the obtained slurry is subjected to pressure filtration to obtain a filter cake, and then the filter cake is subjected to strong drying to obtain nanometer montmorillonite.

2. The process according to claim 1, wherein the process is characterized by: In the roller treatment of step (1), the speed ratio of the front roller to the rear roller is controlled to be 1:1.2-1:1.4; the material is rolled for 2-4 passes, and the roll gap is reduced by 0.5 mm for each pass, and the final rolling thickness is 1 mm.

3. The process according to claim 1, wherein the process is characterized by: In step (2), the first-stage hydrocyclone is composed of 4-6 parallel hydrocyclones with an inner diameter of 75 mm and a cone angle of 6°, and the operating pressure is 0.3 MPa; the second-stage hydrocyclone is composed of 6-8 parallel hydrocyclones with an inner diameter of 50 mm and a cone angle of 6°, and the operating pressure is 0.2 MPa; and the third-stage hydrocyclone is composed of 8-10 parallel hydrocyclones with an inner diameter of 25 mm and a cone angle of 6°, and the operating pressure is 0.2 MPa.

4. The process according to claim 1, wherein the process is characterized by: In step (2), the height-diameter ratio (H / D) of the settling tank is 4:1-5:1, and an ultrasonic interface instrument is arranged to monitor the height of the mineral phase interface in real time; when the interface height decreases at a rate of ≤2% / h of the height of the settling tank, it is determined that the slurry solid-liquid separation is completed.

5. The process according to claim 1, wherein the process is characterized by: In step (2), the three-roller grinding process parameters are as follows: the speed ratio of the rear roller to the middle roller to the front roller is controlled to be 1:2.5:7-1:3:9; the roll gap of the rear roller and the middle roller is 50-100 μm, and the roll gap of the middle roller and the front roller is 15-20 μm; and the material is ground for 2-4 times.

6. The process according to claim 1, wherein the process is characterized by: In step (3), the power density of the ultrasonic peeling is 100-200 W / L, the frequency is 20-40 kHz, and the treatment time is 8-12 min; and the pressure of the high-pressure homogenization peeling is 30-60 MPa.

7. The integrated preparation process of nano-montmorillonite as described in claim 1, characterized in that: In step (3), the ultrasonic peeling, the high-pressure homogenization peeling or the combination thereof can be repeatedly implemented or circularly performed.

8. The process according to claim 1, wherein the process is characterized by: In step (3), the pressure filtration is performed by using a plate-and-frame pressure filter or a high-pressure diaphragm pressure filter, the feeding pressure is 1.6-2.5 MPa, and the moisture content of the obtained filter cake is 30%-40%.

9. The process according to claim 1, wherein the process is characterized by: In step (3), the strong drying process conditions are as follows: the drying temperature is 90-100 ℃, and the classification frequency is 5-25 HZ.

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