A method for producing sodium-based bentonite from calcium-based bentonite

Abstract

This invention belongs to the field of sodium-based bentonite technology, specifically relating to a method for producing sodium-based bentonite from calcium-based bentonite, comprising the following steps: S1. Preliminary mixing: crushing calcium-based bentonite to 90-110 mesh, and then mixing it with a composite sodium-forming agent at a mass ratio of 1:(0.03~0.10); S2. Mechanical shearing: processing the mixture obtained in step S1 in a high-speed shearing machine at a speed of 2000~4000 r / min for 10~40 min; S3. Sodium formation: adding 1~1.5 times its mass of deionized water to the bentonite after mechanical shearing in step S2, and stirring and reacting at a temperature of 60~80℃ for 1~2 h; S4. Drying: centrifuging and dehydrating the sodium-formed bentonite in step S3, drying it at 120~150℃, and pulverizing it to 200~300 mesh to obtain the product. The present invention provides a method for producing sodium-based bentonite from calcium-based bentonite. The preparation method is simple, with high sodiumization efficiency and short reaction time. For the first time, rare earth catalysis, nano-intercalation and bio-based additives are combined, breaking through the traditional sodiumization theoretical framework. The prepared product has good performance, high expansion capacity, and meets the standards of high-end foundry bentonite, making it suitable for high-end application scenarios.

Description

Technical Field

[0001] This invention belongs to the field of sodium-based bentonite technology, specifically relating to a method for producing sodium-based bentonite using calcium-based bentonite. Background Technology

[0002] Calcium-based bentonite is mainly composed of montmorillonite, and its exchangeable cations are primarily Ca²⁺. + Naturally formed, it has a relatively hard texture, low water absorption and swelling (swelling ratio approximately 3-5 times), poor dispersibility, and a neutral to slightly alkaline pH. Its advantages include: low cost (abundant natural resources, no modification required), good thermal stability (not prone to cracking at high temperatures), and moderate adsorption capacity, suitable for some industrial needs. However, its weak swelling and binding properties limit its applications; sodium modification is required for high-performance applications. It is mainly used as a general sand-type binder, iron ore pellet binder, soil conditioner, fertilizer carrier, and for the initial adsorption of pollutants (modification is required for higher efficiency).

[0003] Sodium-based bentonite-montmorillonite is the main component, and the exchangeable cation is Na. + Natural sources are rare; most are calcium-based compounds obtained through sodium modification (alkali alteration). They exhibit extremely high water absorption and swelling capacity (swelling ratio 15-30 times), good dispersibility, high viscosity, and a slightly alkaline pH. Their advantages include high swelling capacity, strong adhesion, good colloidal suspension stability, and strong adsorption capacity, making them suitable for high-end applications. However, they are costly (requiring processing or reliance on scarce natural resources) and may shrink due to water loss at high temperatures. They are mainly used as mud thickeners, wellbore stabilizers, seepage barriers, tunnel shield lubrication, wastewater treatment adsorbents, thickeners in cat litter and skincare products, and bonding agents for precision casting molding sand.

[0004] Calcium-based bentonite: Economical and suitable for basic industries, but its performance is limited and requires modification for improvement. Sodium-based bentonite: High-performance and widely used, but dependent on processing or scarce resources, resulting in higher costs.

[0005] CN110606494A discloses a method for producing sodium-based bentonite from calcium-based bentonite. The method involves: drying the calcium-based bentonite ore to a moisture content of 13%-18%; adding 20 kg of alkali to every 1000 kg of ore; mixing thoroughly in a mixer; crushing large pieces in a crusher; adding water and mixing thoroughly; and then extruding in an electrically heated extruder (power above 300W, pressing temperature above 80°C) for 15-30 minutes to complete the modification. The expansion ratio is 1:30. This method is mainly applicable to modifying natural bentonite into sodium-based bentonite through artificial extrusion. The successfully modified sodium-based bentonite is suitable for use as an adhesive in products such as coatings and putty powder. This invention has the advantages of simple process, few additives, low cost, and fast processing. However, its performance is still not ideal.

[0006] Traditional sodium-based bentonite production processes face three major technical bottlenecks: (1) Low ion exchange efficiency: The binding energy between calcium ions and montmorillonite lattice is as high as 158 kJ / mol, making it difficult for conventional sodium-based agents to achieve deep exchange. Dry processes require long-term calcination, resulting in high energy consumption and lattice damage. (2) Reaction kinetic limitations: Although wet processes can improve reaction activity, sodium ion diffusion is hindered. Calcium-based bentonite swells upon contact with water to form a gel layer, preventing sodium ions from diffusing into the crystal layer. (3) Unstable product performance: Although semi-dry processes can shorten reaction time, uneven mixing leads to incomplete local sodium-based sodium-based sodium-based sodium-based sodium-based sodium-based bentonite. Therefore, a new method for producing sodium-based bentonite from calcium-based bentonite is needed. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention provides a method for producing sodium-based bentonite from calcium-based bentonite, comprising the following steps:

[0008] S1. Preliminary mixing: Crush calcium-based bentonite to 90-110 mesh, then mix it with the composite sodium-based agent at a mass ratio of 1:(0.03~0.10);

[0009] S2. Mechanical shearing: The mixture obtained in step S1 is processed in a high-speed shearing machine at a speed of 2000~4000 r / min for 10~40 min;

[0010] S3. Sodiumization: Add 1 to 1.5 times the mass of the bentonite obtained from mechanical shearing in step S2 to deionized water, and stir and react at 60 to 80°C for 2 to 4 hours.

[0011] S4. Drying: The bentonite after sodium treatment in step S3 is centrifuged to dehydrate, dried at 120~150℃, and pulverized to 200~300 mesh to obtain the product.

[0012] Further, in step S1, the composite sodium-forming agent is a mixture of sodium carbonate, sodium polyacrylate, sodium silicate, montmorillonite nanosheets, and lanthanum oxide. Sodium carbonate is the main sodium-forming agent, providing the primary Na+. + Ca² replacement + Sodium polyacrylate is an anionic polyelectrolyte that prevents agglomeration by generating electrostatic repulsion through adsorption on the particle surface; Sodium silicate: hydrolyzes to form SiO2. 2- With OH - This creates an alkaline environment that promotes CaCO3 precipitation, while SiO2... 2- Intercalation enhances structural stability; montmorillonite nanosheets expand interlayer spacing through intercalation exfoliation effect, providing Na + Rapid diffusion channels shorten the ion replacement path and accelerate the replacement rate; rare earth ions and Ca²⁺ in the montmorillonite interlayer. +The formation of a [La-Ca-O] transition state complex lowers the substitution activation energy and increases the reaction rate. The composite sodium-forming agent forms a multi-component complex system, with montmorillonite nanosheets and lanthanum oxide working synergistically to significantly increase the sodium-forming rate.

[0013] Furthermore, the mass ratio of sodium carbonate, sodium polyacrylate, sodium silicate, montmorillonite nanosheets, and lanthanum oxide is 10:2:0.8:0.2:0.01.

[0014] Further, the mechanical shearing process in step S2 is as follows: first, the particle is treated at a rotation speed of 2000 r / min for 15 min, and then the rotation speed is increased to 3500 r / min for 10 min. The first stage of the shearing process (2000 r / min) breaks the van der Waals forces between particles, allowing the sodium-containing agent to be initially dispersed; the second stage (3500 r / min) generates high shear force, reducing the particle size from 50 μm to 8 μm and increasing the specific surface area.

[0015] Further, in step S3, 0.6 wt% of an auxiliary agent, namely trisodium citrate, is added to the deionized water. Trisodium citrate acts as a chelating agent, reacting with Ca²⁺ in the solution. + The formation of stable complexes shifts the equilibrium of the substitution reaction toward the product, increasing the sodiumization rate.

[0016] Further, in step S3, 0.6 wt% of an auxiliary agent is added to the deionized water. This auxiliary agent is a mixture of sodium polyaspartate and chitosan quaternary ammonium salt, with a mass ratio of sodium polyaspartate to chitosan quaternary ammonium salt of 1:1. Sodium polyaspartate contains carboxylic acid groups and Ca²⁺... + Chelation, while simultaneously anchoring to the montmorillonite interlayer through hydrogen bonds to inhibit recalcification; the cationic properties of chitosan quaternary ammonium salt neutralize the negative charge on the particle surface, promoting flocculation and dehydration.

[0017] Furthermore, in step S3, the mixture before adding water is first treated with microwaves at a frequency of 2.45 GHz and a power of 500 W for 5 minutes, and then treated with ultrasound at a frequency of 20 kHz and a power of 100 W for 10 minutes. The microwave thermal effect selectively heats polar molecules, generating local hot spots that accelerate the desorption of water molecules between layers. The ultrasound generates microjets that impact the particle surface, increasing surface porosity and promoting the sodiumization reaction.

[0018] The present invention provides a method for producing sodium-based bentonite from calcium-based bentonite. The preparation method is simple, with high sodiumization efficiency and short reaction time. For the first time, rare earth catalysis, nano-intercalation and bio-based additives are combined, breaking through the traditional sodiumization theoretical framework. The prepared product has good performance, high expansion capacity, and meets the standards of high-end foundry bentonite, making it suitable for high-end application scenarios. Detailed Implementation

[0019] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0020] Example 1

[0021] A method for producing sodium-based bentonite from calcium-based bentonite includes the following steps:

[0022] S1. Preliminary mixing: Crush 10kg of calcium-based bentonite to 90-110 mesh, and then mix it with 600g of compound sodium-based agent;

[0023] S2. Mechanical shearing: The mixture obtained in step S1 is first processed in a high-speed shearing machine at a speed of 2000 r / min for 15 min, and then the speed is increased to 3500 r / min for 10 min.

[0024] S3. Sodiumization: Add 12 kg of deionized water to the bentonite that was mechanically sheared in step S2, and stir and react at 70~80℃ for 1.8 h.

[0025] S4. Drying: The bentonite after sodium treatment in step S3 is centrifuged to dehydrate, dried at 140~150℃, and pulverized to 200~300 mesh to obtain the product.

[0026] In step S1, the composite sodium-containing agent is a mixture of sodium carbonate, sodium polyacrylate, sodium silicate, montmorillonite nanosheets, and lanthanum oxide, with the following masses: sodium carbonate 461.18g, sodium polyacrylate 92.24g, sodium silicate 36.89g, montmorillonite nanosheets 9.22g, and lanthanum oxide 0.46g.

[0027] The bentonite prepared using the above method meets the standards for high-end foundry bentonite and is suitable for high-end application scenarios.

[0028] Example 2

[0029] A method for producing sodium-based bentonite from calcium-based bentonite includes the following steps:

[0030] S1. Preliminary mixing: Crush 10kg of calcium-based bentonite to 90-110 mesh, and then mix it with 600g of compound sodium-based agent;

[0031] S2. Mechanical shearing: The mixture obtained in step S1 is first processed in a high-speed shearing machine at a speed of 2000 r / min for 15 min, and then the speed is increased to 3500 r / min for 10 min.

[0032] S3. Sodiumization: The bentonite after mechanical shearing in step S2 is treated with microwave at a frequency of 2.45 GHz and a power of 500 W for 5 min, and then treated with ultrasonic at a frequency of 20 kHz and a power of 100 W for 10 min. Then, 12 kg of deionized water is added, and the mixture is stirred and reacted at a temperature of 70~80℃ for 1.6 h.

[0033] S4. Drying: The bentonite after sodium treatment in step S3 is centrifuged to dehydrate, dried at 140~150℃, and pulverized to 200~300 mesh to obtain the product.

[0034] In step S1, the composite sodium-containing agent is a mixture of sodium carbonate, sodium polyacrylate, sodium silicate, montmorillonite nanosheets, and lanthanum oxide, with the following masses: sodium carbonate 461.18g, sodium polyacrylate 92.24g, sodium silicate 36.89g, montmorillonite nanosheets 9.22g, and lanthanum oxide 0.46g.

[0035] The bentonite prepared using the above method meets the standards for high-end foundry bentonite and is suitable for high-end application scenarios.

[0036] Example 3

[0037] A method for producing sodium-based bentonite from calcium-based bentonite includes the following steps:

[0038] S1. Preliminary mixing: Crush 10kg of calcium-based bentonite to 90-110 mesh, and then mix it with 600g of compound sodium-based agent;

[0039] S2. Mechanical shearing: The mixture obtained in step S1 is first processed in a high-speed shearing machine at a speed of 2000 r / min for 15 min, and then the speed is increased to 3500 r / min for 10 min.

[0040] S3. Sodiumization: The bentonite after mechanical shearing in step S2 is treated with microwave at a frequency of 2.45 GHz and a power of 500 W for 5 min, and then treated with ultrasonic at a frequency of 20 kHz and a power of 100 W for 10 min. Then, 12 kg of deionized water is added, and the mixture is stirred and reacted at a temperature of 70~80℃ for 1.6 h. 72 g of trisodium citrate is added to the deionized water.

[0041] S4. Drying: The bentonite after sodium treatment in step S3 is centrifuged to dehydrate, dried at 140~150℃, and pulverized to 200~300 mesh to obtain the product.

[0042] In step S1, the composite sodium-containing agent is a mixture of sodium carbonate, sodium polyacrylate, sodium silicate, montmorillonite nanosheets, and lanthanum oxide, with the following masses: sodium carbonate 461.18g, sodium polyacrylate 92.24g, sodium silicate 36.89g, montmorillonite nanosheets 9.22g, and lanthanum oxide 0.46g.

[0043] The bentonite prepared using the above method meets the standards for high-end foundry bentonite and is suitable for high-end application scenarios.

[0044] Example 4

[0045] A method for producing sodium-based bentonite from calcium-based bentonite includes the following steps:

[0046] S1. Preliminary mixing: Crush 10kg of calcium-based bentonite to 90-110 mesh, and then mix it with 600g of compound sodium-based agent;

[0047] S2. Mechanical shearing: The mixture obtained in step S1 is first processed in a high-speed shearing machine at a speed of 2000 r / min for 15 min, and then the speed is increased to 3500 r / min for 10 min.

[0048] S3. Sodiumization: The bentonite after mechanical shearing in step S2 is microwaved at a frequency of 2.45 GHz and a power of 500 W for 5 min, and then ultrasonically treated at a frequency of 20 kHz and a power of 100 W for 10 min. Then, 12 kg of deionized water is added, and the mixture is stirred and reacted at a temperature of 70~80℃ for 1.6 h. 36 g of sodium polyaspartate and 36 g of chitosan quaternary ammonium salt are added to the deionized water.

[0049] S4. Drying: The bentonite after sodium treatment in step S3 is centrifuged to dehydrate, dried at 140~150℃, and pulverized to 200~300 mesh to obtain the product.

[0050] In step S1, the composite sodium-containing agent is a mixture of sodium carbonate, sodium polyacrylate, sodium silicate, montmorillonite nanosheets, and lanthanum oxide, with the following masses: sodium carbonate 461.18g, sodium polyacrylate 92.24g, sodium silicate 36.89g, montmorillonite nanosheets 9.22g, and lanthanum oxide 0.46g.

[0051] The bentonite prepared using the above method meets the standards for high-end foundry bentonite and is suitable for high-end application scenarios.

[0052] Comparative Example 1

[0053] The components of 9.22g of montmorillonite nanosheets and 0.46g of lanthanum oxide in Example 1 were removed, and the rest were the same as in Example 1, so they will not be repeated here.

[0054] Comparative Example 2

[0055] The 36.89g sodium silicate component in Example 1 was removed, and the rest was the same as in Example 1, so it will not be repeated here.

[0056] The sodium-based bentonite prepared in the above examples and comparative examples was subjected to performance tests, and the results are shown in Table 1.

[0057] Table 1

[0058]

[0059] As can be seen from the data in the table above, the data from Examples 1-3 indicate that the sodium-based bentonite prepared by this invention has an expansion capacity greater than 50 mL / g and a Ca²⁺ content greater than 50 mL / g. + With a replacement rate greater than 97% and a sodiumization time of less than 2 hours, product performance can be improved through microwave light treatment and the addition of additives. Data from Comparative Example 1 show that montmorillonite nanosheets and lanthanum oxide can significantly enhance Ca²⁺... + The replacement rate and sodiumization time, as shown in Comparative Example 2, indicate that sodium silicate can improve the Ca²⁺ concentration to a certain extent. + Displacement rate and sodiumization time.

Claims

1. A method for producing sodium-based bentonite from calcium-based bentonite, characterized in that, Includes the following steps: S1. Preliminary mixing: Crush calcium-based bentonite to 90-110 mesh, then mix it with the composite sodium-based agent at a mass ratio of 1:(0.03~0.10); S2. Mechanical shearing: The mixture obtained in step S1 is processed in a high-speed shearing machine at a speed of 2000~4000 r / min for 10~40 min; S3. Sodiumization: Add 1 to 1.5 times the mass of the bentonite obtained from mechanical shearing in step S2 to deionized water, and stir and react at a temperature of 60 to 80°C for 1 to 2 hours. S4. Drying: The bentonite after sodium treatment in step S3 is centrifuged to dehydrate, dried at 120~150℃, and pulverized to 200~300 mesh to obtain the product; In step S1, the composite sodium oxidizing agent is a mixture of sodium carbonate, sodium polyacrylate, sodium silicate, montmorillonite nanosheets, and lanthanum oxide, wherein the mass ratio of sodium carbonate, sodium polyacrylate, sodium silicate, montmorillonite nanosheets, and lanthanum oxide is 10:2:0.8:0.2:0.

01.

2. The method for producing sodium-based bentonite from calcium-based bentonite according to claim 1, characterized in that, The mechanical shearing process in step S2 is as follows: first, the rotation speed is 2000 r / min for 15 min, and then the rotation speed is increased to 3500 r / min for 10 min.

3. The method for producing sodium-based bentonite from calcium-based bentonite according to claim 1, characterized in that, In step S3, 0.6 wt% of an auxiliary agent, namely trisodium citrate, is added to the deionized water.

4. The method for producing sodium-based bentonite from calcium-based bentonite according to claim 1, characterized in that, In step S3, 0.6 wt% of an auxiliary agent is added to the deionized water. The auxiliary agent is a mixture of sodium polyaspartate and chitosan quaternary ammonium salt, with a mass ratio of sodium polyaspartate and chitosan quaternary ammonium salt of 1:

1.

5. The method for producing sodium-based bentonite from calcium-based bentonite according to claim 1, characterized in that, In step S3, the mixture before adding water is first treated with microwaves at a frequency of 2.45 GHz and a power of 500 W for 5 minutes, and then treated with ultrasound at a frequency of 20 kHz and a power of 100 W for 10 minutes.

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