Ultrasonic microflow preparation method and application of nano calcium silicate nucleating agent

Abstract

The invention provides an ultrasonic micro-flow preparation method and application of a nano calcium silicate nucleating agent, and relates to the technical field of nano material preparation. A calcium salt solution, a silicate solution and a dispersing agent solution are conveyed into an ultrasonic micro-flow control reactor for reaction; by regulating and controlling various parameters such as ultrasonic power, ultrasonic frequency and micro-channel inner diameter, a synergistic effect is exerted, rapid synthesis of the nano calcium silicate nucleating agent is realized, and the technical problems of long reaction time, low reaction efficiency and low concentration of a calcium silicate solution during preparation of nano calcium silicate in the prior art are solved. The technical effects of fast mass and heat transfer, short reaction time, high production efficiency, high calcium silicate concentration and easy enlargement of industrialization are achieved, and the obtained nano calcium silicate nucleating agent is beneficial for improving the early strength performance of cement and has no influence on the later strength of the cement.

Description

Technical Field

[0001] The invention relates to the technical field of nano material preparation, in particular to an ultrasonic micro-flow preparation method of a nano calcium silicate crystal nucleus agent and application thereof. Background Art

[0002] Cement is an indispensable basic material in modern construction, and its performance directly affects the quality, lifespan and safety of buildings. Cement compressive strength is one of the main indicators of cement performance, and compressive strength is often affected by the degree of hydration, the type and microstructure of hydration products, and the porosity.

[0003] In order to improve the compressive strength of cement, various cement early strength agents or enhancers have been widely studied and applied; these early strength agents or enhancers improve the performance of cement by providing additional crystal nuclei, changing the structure of hydration products, improving the dispersibility of cement paste, etc. However, traditional cement early strength agents still have certain limitations in improving early strength and long-term durability.

[0004] At present, nano calcium silicate has great advantages in improving the early strength of cement. However, since nano calcium silicate is mainly synthesized through a kettle stirring process, it takes a long time. It often takes more than several hours from dropwise addition and stirring to obtaining a sample, which greatly affects the production efficiency and cannot respond to production needs in a timely manner. At the same time, there is a problem of slow mass transfer in the synthesis process of nano calcium silicate, and the stirring process is affected by fluid mass transfer, shear force, etc. during the scale-up production process. During the scale-up process, due to the jump in Reynolds number, the mixing efficiency of the fluid cannot be simply scaled up in proportion. The resulting difference in fluid dynamics parameters needs to be adjusted repeatedly, so it is necessary to gradually scale up and continuously adjust equipment, process routes and parameters to solve the industrial production process, which prolongs the R&D cycle and production cost of the project's industrial process; in addition, the solid content of calcium silicate in the calcium silicate solution obtained by the traditional stirring process is often low, usually less than 20%, which affects the transportation efficiency to a certain extent.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] One of the purposes of the present invention is to provide an ultrasonic microfluidic preparation method of a nano calcium silicate crystal nucleus agent, which has the advantages of fast mass and heat transfer, short reaction time, high production efficiency, high calcium silicate concentration and easy industrialization compared with the traditional kettle stirring process.

[0007] The second purpose of the present invention is to provide an application of a nano calcium silicate crystal nucleating agent, which is beneficial to improving the early strength performance of cement while having no effect on the later strength of cement.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] In a first aspect, an ultrasonic microfluidic preparation method of a nano calcium silicate crystal nucleating agent comprises the following steps:

[0010] The calcium salt solution, the silicate solution and the dispersant solution are transported to an ultrasonic microfluidic reactor for reaction to obtain the nano calcium silicate crystal nucleus agent;

[0011] The residence time of the reaction in the microchannel of the ultrasonic microfluidic reactor is 5s to 60s;

[0012] The ultrasonic power of the ultrasonic microfluidic reactor is 10W to 300W, and the ultrasonic frequency is 10kHz to 200kHz;

[0013] The inner diameter of the microchannel is 20 μm to 500 μm;

[0014] The ratio of the ultrasonic power to the inner diameter of the microchannel is 0.5W / μm to 2W / μm; meanwhile, the product of the ultrasonic frequency and the residence time is 500kHz·s to 9000kHz·s.

[0015] Furthermore, the calcium salt solution includes at least one of a calcium chloride aqueous solution, a calcium formate aqueous solution, a calcium nitrate aqueous solution, a calcium oxalate aqueous solution, a calcium hypochlorite aqueous solution and a calcium acetate aqueous solution.

[0016] Furthermore, the mass proportion of calcium salt in the calcium salt solution is 30% to 60%.

[0017] Furthermore, the silicate solution includes at least one of a potassium silicate aqueous solution, a potassium aluminum silicate aqueous solution and a sodium metasilicate aqueous solution.

[0018] Furthermore, the mass percentage of silicate in the silicate solution is 25% to 50%.

[0019] Further, the dispersant solution includes at least one of a polyvinyl pyrrolidone aqueous solution, a polycarboxylic acid polymer aqueous solution, a methyl cellulose aqueous solution, and a polyvinyl alcohol aqueous solution;

[0020] The pH of the dispersant solution is controlled to be 7-9.

[0021] Furthermore, the mass proportion of the dispersant in the dispersant solution is 10% to 30%.

[0022] Furthermore, the preparation method comprises the following steps:

[0023] The calcium salt solution, the silicate solution and the dispersant solution are respectively pumped into an ultrasonic microfluidic reactor through pipelines for reaction to obtain the nano calcium silicate crystal nucleus agent;

[0024] The mass ratio of the calcium salt solution, the silicate solution and the dispersant solution is between (0.2-0.5):(0.2-0.4):1.

[0025] Furthermore, taking the total solution delivery flow rate as 100%, the flow rate of the calcium salt solution accounts for 10% to 25%, the flow rate of the silicate solution accounts for 15% to 35%, and the flow rate of the dispersant solution accounts for 25% to 60%.

[0026] In a second aspect, a nano calcium silicate nucleating agent prepared by the ultrasonic microfluidic preparation method described in any one of the above items is used in a cement early strength agent.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] Compared with the traditional kettle stirring process for preparing nano calcium silicate materials, the ultrasonic microfluidic preparation method of the nano calcium silicate nucleus agent provided by the present invention has the following advantages: (1) fast mass and heat transfer. Since the micron-level channel of the ultrasonic microfluidic reactor has an ultra-large specific surface area, the material can respond quickly, effectively improving the reaction efficiency; (2) short reaction time. Since the microfluidic process regulates the reaction microenvironment, the material can fully react in a very short time, effectively reducing the time required for the reaction and shortening the reaction time to 5s to 60s; (3) the calcium silicate solution has a high concentration. Ultrasonic energy is provided by ultrasound, and ultrasonic cavitation generates microbubbles in the fluid in the microchannel, which helps to improve the dispersion of calcium silicate in the solution, so that the concentration of calcium silicate can be increased to 22% to 35%, and the solution stability is good; (4) There is no amplification effect. The ultrasonic microfluidic process does not need to explore the amplification process. Industrial amplification production can be achieved by increasing the number of microchannels, which greatly shortens the industrial research and development cycle; (5) The nano calcium silicate nucleus agent prepared by the ultrasonic microfluidic process can effectively improve the early strength performance of cement, and has no effect on the later strength of cement.

[0029] The application of the nano calcium silicate crystal nucleating agent provided by the present invention is beneficial to improving the early strength performance of cement, while having no influence on the later strength of cement. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1This is a transmission electron microscope image of nano calcium silicate provided in Example 1 of the present invention;

[0032] Figure 2 This is a state diagram of the nano calcium silicate crystal nucleus agent obtained in the test example of the present invention after being placed for one day;

[0033] Figure 3 This is a state diagram of the nano calcium silicate crystal nucleus agent obtained in the test example of the present invention after being placed for one month. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] According to a first aspect of the present invention, there is provided an ultrasonic microfluidic preparation method of a nano calcium silicate crystal nucleating agent, comprising the following steps:

[0036] The calcium salt solution, the silicate solution and the dispersant solution are transported to an ultrasonic microfluidic reactor for reaction to obtain a nano calcium silicate crystal nucleus agent;

[0037] The residence time of the reaction in the microchannel of the ultrasonic microfluidic reactor can be 5s to 60s, and its typical but non-limiting residence time is, for example, 5s, 10s, 20s, 30s, 40s, 50s, and 60s;

[0038] The ultrasonic power of the ultrasonic microfluidic reactor can be 10W to 300W, and its typical but non-limiting ultrasonic power is, for example, 10W, 50W, 100W, 150W, 200W, 250W, and 300W. The ultrasonic frequency can be 10kHz to 200kHz, and its typical but non-limiting ultrasonic frequency is, for example, 10kHz, 20kHz, 30kHz, 40kHz, 50kHz, 60kHz, 70kHz, 80kHz, 90kHz, 100kHz, 120kHz, 140kHz, 160kHz, 180kHz, and 200kHz.

[0039] It should be noted that appropriate ultrasonic power and ultrasonic frequency can improve the stability and uniformity of distribution of calcium silicate solution; if the ultrasonic power is too low, the stability of the calcium silicate solution will decrease; if the ultrasonic power is too high, the reaction system will overheat and induce phase separation of the solution; if the ultrasonic frequency is too low, the ultrasonic cavitation effect will not be significant and the reaction efficiency will be reduced; if the ultrasonic frequency is too high, the cavitation threshold will increase, and higher power will be required to stimulate the cavitation process, which will also affect the reaction efficiency.

[0040] Meanwhile, the inner diameter of the microchannel may be 20 μm to 500 μm, and typical but non-limiting inner diameters thereof are, for example, 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 150 μm, 200 μm, 300 μm, 400 μm, and 500 μm;

[0041] It is particularly important that the ratio of ultrasonic power to microchannel inner diameter is 0.5W / μm to 2W / μm; at the same time, the product of ultrasonic frequency and residence time is 500kHz·s to 9000kHz·s.

[0042] The invention can rapidly synthesize nano calcium silicate nucleus agent through ultrasonic microfluidic process, and effectively realizes rapid synthesis of nano calcium silicate by regulating the microenvironment of the synthesis process, greatly improves the synthesis efficiency of nano calcium silicate, and shortens the reaction time; compared with the traditional microfluidics, the invention innovatively introduces ultrasound on the basis of microfluidics technology, provides more energy and cavitation bubbles for the reaction, and the acoustic cavitation effect brought about by the ultrasonic microfluidic process can further improve the reaction rate and the dispersibility of calcium silicate in the solution, effectively improves the concentration of the calcium silicate solution, and will not cause the blockage of the synthesized nanoparticles in the microchannels; the invention is used as a cement early strength agent in cement, which can effectively improve the early strength of cement, and the later strength of cement will not have the problem of shrinkage; therefore, the invention solves the problems of long reaction time, slow mass transfer, low production efficiency and low concentration of calcium silicate solution in the preparation of nano calcium silicate by the traditional kettle stirring process.

[0043] It should be noted that the nano calcium silicate nucleating agent is mainly composed of calcium silicate nanomaterials, water and dispersants; in the nano calcium silicate nucleating agent, calcium silicate serves as the main nucleating agent and organic matter serves as a dispersant, thereby forming a dispersed nano calcium silicate nucleating agent, which can provide more nucleation sites for the cement hydration product hydrated calcium silicate gel, effectively reduce its nucleation barrier, accelerate the degree of cement hydration, and is beneficial to improving the early strength of cement.

[0044] In a preferred embodiment, the calcium salt solution includes but is not limited to at least one of a calcium chloride aqueous solution, a calcium formate aqueous solution, a calcium nitrate aqueous solution, a calcium oxalate aqueous solution, a calcium hypochlorite aqueous solution and a calcium acetate aqueous solution; at the same time, the mass proportion of the calcium salt in the calcium salt solution can be 30% to 60%, and its typical but non-limiting mass proportion is, for example, 30%, 40%, 50%, and 60%.

[0045] In a preferred embodiment, the silicate solution includes but is not limited to at least one of an aqueous potassium silicate solution, an aqueous potassium aluminum silicate solution and an aqueous sodium metasilicate solution; at the same time, the mass proportion of silicate in the silicate solution can be 25% to 50%, and its typical but non-limiting mass proportion is, for example, 25%, 30%, 35%, 40%, 45%, and 50%.

[0046] In the present invention, the dispersant solution includes but is not limited to at least one of a polyvinyl pyrrolidone aqueous solution, a polycarboxylic acid polymer aqueous solution, a methyl cellulose aqueous solution and a polyvinyl alcohol aqueous solution; the mass proportion of the dispersant in the dispersant solution can be 10% to 30%, and its typical but non-limiting mass proportion is, for example, 10%, 15%, 20%, 25%, and 30%.

[0047] It should be noted that the pH of the dispersant solution can be controlled to be 7-9.

[0048] In a preferred embodiment, the preparation method of the present invention comprises the following steps:

[0049] The calcium salt solution, the silicate solution and the dispersant solution are respectively pumped into an ultrasonic microfluidic reactor through pipelines for reaction to obtain a nano calcium silicate crystal nucleus agent;

[0050] The mass ratio of the calcium salt solution, the silicate solution and the dispersant solution can be controlled between (0.2-0.5):(0.2-0.4):1.

[0051] In a preferred embodiment, based on the total solution delivery flow rate of 100%, the flow rate of the calcium salt solution may account for 10% to 25%, the flow rate of the silicate solution may account for 15% to 35%, and the flow rate of the dispersant solution may account for 25% to 60%.

[0052] In the present invention, the reaction process of the ultrasonic microfluidic method is effectively optimized by the coordinated cooperation of specific process parameters such as solution concentration, reaction time, solution flow rate and ultrasonic power, so that the nano calcium silicate solution can still remain stable at high concentration.

[0053] A typical preparation method of nano calcium silicate crystal nucleating agent by ultrasonic microflow includes the following steps:

[0054] (1) Preparation of solution:

[0055] A calcium salt aqueous solution is prepared, wherein the calcium salt used is at least one selected from calcium chloride, calcium formate, calcium nitrate, calcium oxalate, calcium hypochlorite and calcium acetate, and the mass proportion of the calcium salt in the calcium salt aqueous solution is 30% to 60%;

[0056] Prepare a silicate aqueous solution, wherein the silicate used is selected from at least one of potassium silicate, potassium aluminum silicate and sodium metasilicate, and the mass proportion of the silicate in the silicate aqueous solution is 25% to 50%;

[0057] Prepare a dispersant aqueous solution, wherein the dispersant used is selected from at least one of polyvinyl pyrrolidone, polycarboxylic acid polymer, methyl cellulose and polyvinyl alcohol, and the mass proportion of the dispersant in the dispersant aqueous solution is 10% to 30%;

[0058] (2) Ultrasonic microfluidic process:

[0059] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is controlled between (0.2-0.5): (0.2-0.4): 1;

[0060] A calcium salt aqueous solution, a silicate aqueous solution and a dispersant aqueous solution are pumped into an ultrasonic microfluidic reactor through three-way pipelines for reaction. Taking the total solution transport flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 10% to 25%, the flow rate of the silicate aqueous solution accounts for 15% to 35%, the flow rate of the dispersant aqueous solution accounts for 25% to 60%, the residence time of the reaction in the microchannel of the ultrasonic microfluidic reactor is 5s to 60s, the ultrasonic power of the ultrasonic microfluidic reactor is 10W to 300W, the ultrasonic frequency is 10kHz to 200kHz, the inner diameter of the microchannel is 20μm to 500μm, the ratio of the ultrasonic power to the inner diameter of the microchannel is 0.5W / μm to 2W / μm, and the product of the ultrasonic frequency and the residence time is 500kHz·s to 9000kHz·s, so as to obtain a nano calcium silicate solution, namely a nano calcium silicate crystal nucleating agent.

[0061] Conventional microfluidic processes often use single-channel or two-channel pipelines for sample injection, which makes it impossible to meet the reaction requirements of the samples. The microfluidic method in the present invention can use three-channel pipelines for simultaneous sample injection. Through the coordinated optimization of multiple aspects such as dynamic regulation of pH, flow rate, tube diameter parameters, ultrasonic power and ultrasonic frequency, it can effectively achieve the preparation of stable and high-concentration nanocrystal nucleating agents.

[0062] In summary, the present invention accelerates the synthesis efficiency of nano-calcium silicate through the ultrasonic microfluidic method, effectively shortens the reaction time, utilizes the ultrasonic effect to provide energy, effectively promotes the rapid synthesis of nano-calcium silicate, and further improves the reaction efficiency; at the same time, the present invention increases the concentration of the calcium silicate solution through the ultrasonic microfluidic method, avoids the problem of low concentration of the calcium silicate solution, and ensures that the high-concentration and highly stable solution can be effectively used in industry.

[0063] According to a second aspect of the present invention, there is provided a use of a nano calcium silicate crystal nucleating agent prepared by any of the above-mentioned ultrasonic microfluidic preparation methods in a cement early strength agent.

[0064] The application of the nano calcium silicate crystal nucleating agent provided by the present invention is beneficial to improving the early strength performance of cement, while having no influence on the later strength of cement.

[0065] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0066] Example 1

[0067] An ultrasonic microfluidic preparation method for a nano calcium silicate crystal nucleating agent comprises the following steps:

[0068] (1) Preparation of solution:

[0069] A calcium salt aqueous solution is prepared, wherein the calcium salt used is selected from calcium chloride, and the mass proportion of calcium chloride in the calcium salt aqueous solution is 40%;

[0070] A silicate aqueous solution is prepared, wherein the silicate used is selected from potassium aluminum silicate, and the mass proportion of potassium aluminum silicate in the silicate aqueous solution is 50%;

[0071] Prepare a dispersant aqueous solution, wherein the dispersant used is selected from polyvinyl pyrrolidone, the mass proportion of polyvinyl pyrrolidone in the dispersant aqueous solution is 20%, and the pH is controlled to be 7;

[0072] (2) Ultrasonic microfluidic process:

[0073] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is 0.3:0.3:1;

[0074] A calcium salt aqueous solution, a silicate aqueous solution and a dispersant aqueous solution are pumped into an ultrasonic microfluidic reactor through three-way pipelines for reaction. Taking the total solution transport flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 20%, the flow rate of the silicate aqueous solution accounts for 30%, the flow rate of the dispersant aqueous solution accounts for 50%, the residence time of the reaction in the microchannel of the ultrasonic microfluidic reactor is 30s, the ultrasonic power of the ultrasonic microfluidic reactor is 50W, the ultrasonic frequency is 20kHz, the inner diameter of the microchannel is 50μm, the ratio of the ultrasonic power to the inner diameter of the microchannel is 1W / μm, the product of the ultrasonic frequency and the residence time is 600kHz·s, and a milky white nano calcium silicate solution is obtained, which is the nano calcium silicate crystal nucleating agent.

[0075] Figure 1 This is a transmission electron microscope image of the nano-calcium silicate obtained in this example, and the morphology is a two-dimensional lamellar structure.

[0076] Example 2

[0077] An ultrasonic microfluidic preparation method for a nano calcium silicate crystal nucleating agent comprises the following steps:

[0078] (1) Preparation of solution:

[0079] A calcium salt aqueous solution is prepared, wherein the calcium salt used is selected from calcium nitrate, and the mass proportion of calcium nitrate in the calcium salt aqueous solution is 50%;

[0080] A silicate aqueous solution is prepared, wherein the silicate used is selected from potassium silicate, and the mass proportion of potassium silicate in the silicate aqueous solution is 40%;

[0081] Prepare a dispersant aqueous solution, wherein the dispersant used is selected from methyl cellulose, the mass proportion of methyl cellulose in the dispersant aqueous solution is 15%, and the pH is controlled to be 7.5;

[0082] (2) Ultrasonic microfluidic process:

[0083] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is 0.25:0.3:1;

[0084] A calcium salt aqueous solution, a silicate aqueous solution and a dispersant aqueous solution are pumped into an ultrasonic microfluidic reactor through three-way pipelines for reaction. Taking the total solution transport flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 25%, the flow rate of the silicate aqueous solution accounts for 25%, the flow rate of the dispersant aqueous solution accounts for 50%, the residence time of the reaction in the microchannel of the ultrasonic microfluidic reactor is 60s, the ultrasonic power of the ultrasonic microfluidic reactor is 50W, the ultrasonic frequency is 50kHz, the inner diameter of the microchannel is 100μm, the ratio of the ultrasonic power to the inner diameter of the microchannel is 0.5W / μm, the product of the ultrasonic frequency and the residence time is 3000kHz·s, and a milky white nano calcium silicate solution is obtained, which is the nano calcium silicate crystal nucleating agent.

[0085] Example 3

[0086] An ultrasonic microfluidic preparation method for a nano calcium silicate crystal nucleating agent comprises the following steps:

[0087] (1) Preparation of solution:

[0088] A calcium salt aqueous solution is prepared, wherein the calcium salt used is selected from calcium formate, and the mass proportion of calcium formate in the calcium salt aqueous solution is 35%;

[0089] A silicate aqueous solution is prepared, wherein the silicate used is selected from sodium metasilicate, and the mass proportion of sodium metasilicate in the silicate aqueous solution is 45%;

[0090] Prepare a dispersant aqueous solution, wherein the dispersant used is selected from a polycarboxylic acid polymer, the mass proportion of the polycarboxylic acid polymer in the dispersant aqueous solution is 15%, and the pH is controlled to be 8;

[0091] (2) Ultrasonic microfluidic process:

[0092] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is 0.2:0.3:1;

[0093] A calcium salt aqueous solution, a silicate aqueous solution and a dispersant aqueous solution are pumped into an ultrasonic microfluidic reactor through three-way pipelines for reaction. Taking the total solution transport flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 20%, the flow rate of the silicate aqueous solution accounts for 20%, the flow rate of the dispersant aqueous solution accounts for 60%, the residence time of the reaction in the microchannel of the ultrasonic microfluidic reactor is 10s, the ultrasonic power of the ultrasonic microfluidic reactor is 100W, the ultrasonic frequency is 80kHz, the inner diameter of the microchannel is 150μm, the ratio of the ultrasonic power to the inner diameter of the microchannel is 0.67W / μm, the product of the ultrasonic frequency and the residence time is 800kHz·s, and a milky white nano calcium silicate solution is obtained, which is the nano calcium silicate crystal nucleating agent.

[0094] Example 4

[0095] An ultrasonic microfluidic preparation method for a nano calcium silicate crystal nucleating agent comprises the following steps:

[0096] (1) Preparation of solution:

[0097] A calcium salt aqueous solution is prepared, wherein the calcium salt used is selected from calcium hypochlorite, and the mass proportion of calcium hypochlorite in the calcium salt aqueous solution is 50%;

[0098] A silicate aqueous solution is prepared, wherein the silicate used is selected from sodium metasilicate, and the mass proportion of sodium metasilicate in the silicate aqueous solution is 50%;

[0099] Prepare a dispersant aqueous solution, wherein the dispersant used is selected from polyvinyl alcohol, the mass proportion of polyvinyl alcohol in the dispersant aqueous solution is 20%, and the pH is controlled to be 9;

[0100] (2) Ultrasonic microfluidic process:

[0101] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is 0.4:0.3:1;

[0102] A calcium salt aqueous solution, a silicate aqueous solution and a dispersant aqueous solution are pumped into an ultrasonic microfluidic reactor through three-way pipelines for reaction. Taking the total solution transport flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 25%, the flow rate of the silicate aqueous solution accounts for 30%, and the flow rate of the dispersant aqueous solution accounts for 45%. The residence time of the reaction in the microchannel of the ultrasonic microfluidic reactor is 50s. The ultrasonic power of the ultrasonic microfluidic reactor is 150W, the ultrasonic frequency is 180kHz, the inner diameter of the microchannel is 300μm, the ratio of the ultrasonic power to the inner diameter of the microchannel is 0.5W / μm, and the product of the ultrasonic frequency and the residence time is 9000kHz·s, thereby obtaining a milky white nano calcium silicate solution, namely the nano calcium silicate crystal nucleating agent.

[0103] Example 5

[0104] An ultrasonic microfluidic preparation method for a nano calcium silicate crystal nucleating agent comprises the following steps:

[0105] (1) Preparation of solution:

[0106] A calcium salt aqueous solution is prepared, wherein the calcium salt used is selected from calcium acetate, and the mass proportion of calcium acetate in the calcium salt aqueous solution is 45%;

[0107] A silicate aqueous solution is prepared, wherein the silicate used is selected from potassium silicate, and the mass proportion of potassium silicate in the silicate aqueous solution is 40%;

[0108] Prepare a dispersant aqueous solution, wherein the dispersant used is selected from a polycarboxylic acid polymer, the mass proportion of the polycarboxylic acid polymer in the dispersant aqueous solution is 10%, and the pH is controlled to be 8;

[0109] (2) Ultrasonic microfluidic process:

[0110] The mass ratio of the calcium salt aqueous solution, the silicate aqueous solution and the dispersant aqueous solution is 0.4:0.25:1;

[0111] A calcium salt aqueous solution, a silicate aqueous solution and a dispersant aqueous solution are pumped into an ultrasonic microfluidic reactor through three-way pipelines for reaction. Taking the total solution transport flow rate as 100%, the flow rate of the calcium salt aqueous solution accounts for 20%, the flow rate of the silicate aqueous solution accounts for 25%, and the flow rate of the dispersant aqueous solution accounts for 55%. The residence time of the reaction in the microchannel of the ultrasonic microfluidic reactor is 30s. The ultrasonic power of the ultrasonic microfluidic reactor is 100W, the ultrasonic frequency is 50kHz, the inner diameter of the microchannel is 200μm, the ratio of the ultrasonic power to the inner diameter of the microchannel is 0.5W / μm, and the product of the ultrasonic frequency and the residence time is 1500kHz·s, thereby obtaining a milky white nano calcium silicate solution, namely the nano calcium silicate crystal nucleating agent.

[0112] Comparative Example 1

[0113] The difference between this comparative example and Example 1 is that in this comparative example, no calcium salt aqueous solution, silicate aqueous solution and dispersant aqueous solution are prepared, but only water is transported to the ultrasonic microfluidic reactor;

[0114] The rest are the same as in Example 1.

[0115] Comparative Example 2

[0116] The difference between this comparative example and Example 2 is that in this comparative example, the residence time of the reaction in the microchannel of the ultrasonic microfluidic reactor is 20 s, the ultrasonic power of the ultrasonic microfluidic reactor is 50 W, the ultrasonic frequency is 20 kHz, and the inner diameter of the microchannel is 1000 μm;

[0117] The rest are the same as in Example 1.

[0118] Comparative Example 3

[0119] The difference between this comparative example and Example 2 is that the ultrasonic power of the ultrasonic microfluidic reactor in this comparative example is 5W;

[0120] The rest are the same as in Example 1.

[0121] Comparative Example 4

[0122] The difference between this comparative example and Example 2 is that the ultrasonic power of the ultrasonic microfluidic reactor in this comparative example is 350W;

[0123] The rest are the same as in Example 1.

[0124] Comparative Example 5

[0125] The difference between this comparative example and Example 2 is that the ultrasonic frequency of the ultrasonic microfluidic reactor in this comparative example is 5 kHz;

[0126] The rest are the same as in Example 1.

[0127] Comparative Example 6

[0128] The difference between this comparative example and Example 2 is that the ultrasonic frequency of the ultrasonic microfluidic reactor in this comparative example is 250 kHz;

[0129] The rest are the same as in Example 1.

[0130] Comparative Example 7

[0131] In this comparative example, a conventional stirring process was used to prepare a nano-calcium silicate crystal nucleating agent. The corresponding component ratio was the same as that in Example 1. The specific operation was to simultaneously drop a calcium salt solution and a silicate solution into a dispersant aqueous solution within 15 minutes, control the stirring rate to 800 rpm, and the stirring time to 12 hours to obtain a nano-crystal nucleating agent product.

[0132] Test example

[0133] The products obtained from Examples 1-5 and Comparative Examples 1-7 were used as cement early strength agents in cement to carry out mortar strength tests of P·II type cement, and were respectively recorded as Test Group 1, Test Group 2, Test Group 3, Test Group 4, Test Group 5, Comparative Group 1, Comparative Group 2, Comparative Group 3, Comparative Group 4, Comparative Group 5, Comparative Group 6 and Comparative Group 7, thereby obtaining the cement strengths of different types of cement at different ages, as shown in Table 1.

[0134] Table 1

[0135]

[0136] As can be seen from Table 1, the nano calcium silicate nucleus agent obtained in Examples 1-5 of the present invention is introduced into cement as a cement early strength agent (test groups 1-5), which can effectively improve the early strength of cement (12h), and the improvement effect is significantly better than that of Comparative Examples 1-2. At the same time, it also has a corresponding improvement effect on the compressive strength of 3d and 28d, and does not show the problem of strength shrinkage.

[0137] The actual pictures of the nanocrystalline nucleating agent samples (mass concentration is about 30%) obtained in Example 1 and Comparative Example 7 are shown in Figure 2 and Figure 3 , Figure 2 This is the state after one day of storage. Figure 3 The left picture shows the state after being placed for one month. The left picture shows the nanocrystal nucleus agent sample obtained in Example 1, and the right picture shows the nanocrystal nucleus agent sample obtained in Comparative Example 7. It can be seen that the sample prepared by the stirring process in Comparative Example 7 has poor dispersion and is prone to precipitation, while the sample prepared by the microfluidic control in Example 1 still has no obvious precipitation after being placed for one month, which shows that it has excellent stability and is more suitable for practical applications.

[0138] In summary, the present invention not only quickly prepares the nano calcium silicate crystal nucleus agent through the ultrasonic microfluidic process, but also effectively improves the concentration of the nano calcium silicate solution, the production efficiency of the nano calcium silicate crystal nucleus agent and the stability of the crystal nucleus agent. The obtained nano calcium silicate crystal nucleus agent is used in cement as a cement early strength agent, which can effectively improve the early strength of cement, and at the same time, there is no shrinkage problem in the later strength.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ultrasonic microfluidic preparation method of a nano calcium silicate crystal nucleating agent, characterized in that: The following steps are involved: The calcium salt solution, the silicate solution and the dispersant solution are transported to an ultrasonic microfluidic reactor for reaction to obtain the nano calcium silicate crystal nucleus agent; The residence time of the reaction in the microchannel of the ultrasonic microfluidic reactor is 5s to 60s; The ultrasonic power of the ultrasonic microfluidic reactor is 10W to 300W, and the ultrasonic frequency is 10kHz to 200kHz; The inner diameter of the microchannel is 20 μm to 500 μm; The ratio of the ultrasonic power to the inner diameter of the microchannel is 0.5W / μm to 2W / μm; meanwhile, the product of the ultrasonic frequency and the residence time is 500kHz·s to 9000kHz·s.

2. The ultrasonic microfluidic preparation method according to claim 1, characterized in that: The calcium salt solution includes at least one of a calcium chloride aqueous solution, a calcium formate aqueous solution, a calcium nitrate aqueous solution, a calcium oxalate aqueous solution, a calcium hypochlorite aqueous solution and a calcium acetate aqueous solution.

3. The ultrasonic microfluidic preparation method according to claim 2, characterized in that: The mass proportion of calcium salt in the calcium salt solution is 30% to 60%.

4. The ultrasonic microfluidic preparation method according to claim 1, characterized in that: The silicate solution includes at least one of a potassium silicate aqueous solution, a potassium aluminum silicate aqueous solution, and a sodium metasilicate aqueous solution.

5. The ultrasonic microfluidic preparation method according to claim 4, characterized in that: The mass percentage of silicate in the silicate solution is 25% to 50%.

6. The ultrasonic microfluidic preparation method according to claim 1, characterized in that: The dispersant solution comprises at least one of a polyvinyl pyrrolidone aqueous solution, a polycarboxylic acid polymer aqueous solution, a methyl cellulose aqueous solution and a polyvinyl alcohol aqueous solution; The pH of the dispersant solution is controlled to be 7-9.

7. The ultrasonic microfluidic preparation method according to claim 6, characterized in that: The mass proportion of the dispersant in the dispersant solution is 10% to 30%.

8. The ultrasonic microfluidic preparation method according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: The calcium salt solution, the silicate solution and the dispersant solution are respectively pumped into an ultrasonic microfluidic reactor through pipelines for reaction to obtain the nano calcium silicate crystal nucleus agent; Among them, the mass ratio of calcium salt solution, silicate solution and dispersant solution is (0.2-0.5):(0.2-0.4):

1.

9. The ultrasonic microfluidic preparation method according to claim 8, characterized in that: Taking the total solution delivery flow rate as 100%, the flow rate of the calcium salt solution accounts for 10% to 25%, the flow rate of the silicate solution accounts for 15% to 35%, and the flow rate of the dispersant solution accounts for 25% to 60%.

10. Use of the nano calcium silicate crystal nucleating agent prepared by the ultrasonic microfluidic preparation method according to any one of claims 1 to 9 in cement early strength agent.

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