A synthesis device and method for nano calcium silicate hydrate and the prepared nano calcium silicate hydrate

Abstract

The invention provides a synthesis device and a synthesis method of nano calcium silicate hydrate and the prepared nano calcium silicate hydrate. The synthesis device comprises a raw material preparation unit and a crystallization reaction unit which are sequentially connected along a material flow direction, and the crystallization reaction unit comprises an impinging stream reactor and a tubular reactor which are sequentially connected. A calcium-containing solution and a silicon-containing solution are sent from the raw material preparation unit to the impinging stream reactor for inducing nucleation, and the obtained mixed slurry is sent to the tubular reactor for crystallization reaction, so as to prepare the nano calcium silicate hydrate. The use of the synthesis device of the invention can effectively solve the problem of particle agglomeration during the production of nano calcium silicate hydrate, and does not need to use a medicament, will not cause environmental pollution, can realize the efficient regulation and synthesis of nano calcium silicate hydrate, further improve the production efficiency, and has good industrial application prospects.

Description

Technical Field

[0001] The invention belongs to the field of nano material synthesis, and relates to a synthesis device and a synthesis method of nano calcium silicate hydrate and the prepared nano calcium silicate hydrate. Background Art

[0002] Nano-calcium silicate hydrate is a new type of early-strength nanocomposite material that can effectively improve the early mechanical properties of cement-based materials through the nucleation effect. It can not only accelerate the cement hydration reaction process, but also significantly compensate for the mechanical property defects caused by the addition of low-activity auxiliary cementitious materials. The synthesis methods of nano-calcium silicate hydrate mainly include volcanic ash reaction method, sol-gel method, and precipitation method. However, these methods are prone to agglomeration of calcium silicate hydrate during the synthesis process, thus restricting the effective synthesis of nano-scale calcium silicate hydrate. Currently, mechanical stirring method, ultrasonic separation method, organic dispersant method, etc. are mostly used for agglomeration treatment in the synthesis process of calcium silicate hydrate, all of which aim to reduce the agglomeration of calcium silicate hydrate and improve the production efficiency of nano-calcium silicate hydrate. However, these methods have problems such as high energy consumption, high cost, difficulty in process intensification, and environmental pollution.

[0003] CN114956647A discloses a shrinkage-reducing composite nano-hydrated calcium silicate early strength agent and a preparation method thereof, wherein the early strength agent is prepared by reacting a calcium salt component, a silicon salt component and a shrinkage-reducing-dispersing component in a mass ratio of (0.2-0.6):(0.4-0.7):1; wherein the shrinkage-reducing-dispersing component is an aqueous solution containing a shrinkage-reducing polycarboxylic acid water reducer with a mass fraction of 1%-3% and a polycarboxylic acid dispersant with a mass fraction of 3%-9%. However, in the preparation method of the composite nano-hydrated calcium silicate, the polycarboxylic acid water reducer and the dispersant have high costs and large addition amounts, and the water reducer has an adverse effect on the hydration process of cement-based materials, which seriously restricts the industrial production synthesis and back-end large-scale application of nano-hydrated calcium silicate.

[0004] CN112830710A discloses a coupling agent modified nano calcium silicate hydrate crystal nucleus early strength agent and a preparation method thereof, wherein the coupling agent modified nano calcium silicate hydrate crystal nucleus early strength agent comprises a dispersant with a mass proportion of 1% to 10%, a coupling agent with a mass proportion of 0.05% to 1%, a soluble calcium source and a soluble silicon source synthesized by solution precipitation with a mass proportion of 5% to 30%, and the rest is deionized water, wherein the calcium-silicon molar ratio is 0.5 to 2.0. The coupling agent modified nano calcium silicate hydrate preparation method is: using a polycarboxylic acid dispersant and an aqueous solution of a silane coupling agent as a base material, and simultaneously adding a soluble calcium source aqueous solution and a soluble silicon source aqueous solution to the base material to obtain a nano calcium silicate hydrate crystal nucleus early strength agent. However, in the coupling agent-modified nano-calcium silicate hydrate preparation method, the coupling agent has weak bonding ability with calcium silicate hydrate, a large amount of coupling agent is added and it is easy to remain, and the residual coupling agent will harm the hydration process of cement-based materials, seriously affecting the green and efficient synthesis of nano-calcium silicate hydrate.

[0005] Therefore, how to provide a nano-calcium silicate hydrate synthesis device and method that is simple, efficient, green and environmentally friendly for nanoparticle synthesis has become an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a synthesis device and a synthesis method of nano calcium silicate hydrate and the prepared nano calcium silicate hydrate. The synthesis device comprises a raw material preparation unit and a crystallization reaction unit which are sequentially connected along the material flow direction, and the crystallization reaction unit comprises an impinging stream reactor and a tubular reactor which are sequentially connected; a calcium-containing solution and a silicon-containing solution are sent from the raw material preparation unit to the impinging stream reactor for inducing nucleation, and the obtained mixed slurry is sent to the tubular reactor for crystallization reaction, so as to prepare nano calcium silicate hydrate; the use of the synthesis device of the present invention can effectively solve the problem of particle agglomeration during the production of nano calcium silicate hydrate, and does not need to use a drug, will not cause environmental pollution, can achieve efficient regulation and synthesis of nano calcium silicate hydrate, further improve production efficiency, and has good industrial application prospects.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a synthesis device for nano-calcium silicate hydrate, comprising a raw material preparation unit and a crystallization reaction unit connected in sequence along a material flow direction; the raw material preparation unit comprises a calcium-containing solution preparation device and a silicon-containing solution preparation device; the crystallization reaction unit comprises an impinging stream reactor and a tubular reactor connected in sequence; a first side wall inlet and a second side wall inlet are relatively arranged on the impinging stream reactor, the calcium-containing solution preparation device is connected to the first side wall inlet, and the silicon-containing solution preparation device is connected to the second side wall inlet.

[0009] The present invention prepares nano calcium silicate hydrate by using a combined system of an impinging stream reactor and a tubular reactor. The impinging stream reactor promotes the full mixing and mutual reaction of two rapidly colliding liquid flows by providing a high and uniform supersaturated environment, rapidly produces a large amount of reactants, achieves explosive induction of nucleation under a high supersaturation state, and finally generates a product with a fine particle size. In addition, the tubular reactor of the present invention is a tubular, large-length-to-diameter ratio continuous operation reactor, which can further realize segmented temperature control and plug flow reaction, thereby reducing back mixing and particle collision to avoid agglomeration, and is very suitable for production processes with high crystallization conversion requirements. Therefore, the impinging stream reactor and the tubular reactor are combined and used, on the one hand, the rapid collision-induced nucleation of calcium-containing solution and silicon-containing solution can be realized, and a mixed slurry of a large amount of nano calcium silicate hydrate can be formed; on the other hand, the mixed slurry can be synthesized in a tubular reactor by segmented temperature control to obtain the desired nano calcium silicate hydrate, and the directional regulation of efficient crystal growth of nano calcium silicate hydrate can be realized, which is helpful to improve the product quality and production efficiency of nano calcium silicate hydrate, and has important development prospects and economic benefits.

[0010] The main function of the impinging stream reactor in the present invention is that the collision flow path enables the two fluids to have a very large relative velocity, strong turbulent kinetic energy and strong shear force in the collision zone, increasing the contact area and mixing uniformity of the two raw material solutions. The high Reynolds number state can efficiently and quickly achieve induced nucleation and form a mixed slurry rich in calcium silicate hydrate nuclei, which can be quickly sent to the tubular reactor to avoid premature crystallization growth. The key equipment parameters in the impinging stream reactor are mainly the nozzle height, orientation and angle, and the nozzles can achieve the maximum collision mixing and induction of nucleation of the solution when they are in the same horizontal plane, the same straight line and the center is symmetrical. At the same time, after the mixed slurry rich in calcium silicate hydrate nuclei is sent to the tubular reactor, it can be controlled by segmented coupling such as the required crystallization temperature and crystallization time, such as realizing the crystallization growth of calcium silicate hydrate nuclei with rapid flow under high temperature conditions in a few minutes or even seconds, and the strong turbulent flow system disturbs the agglomeration effect between calcium silicate hydrate particles, realizing the uniform and controllable production of nano calcium silicate hydrate particles. Therefore, the rational combination of the impinging stream reactor and the tubular reactor can efficiently realize the synthesis of nano calcium silicate hydrate products and synergistically avoid the agglomeration of calcium silicate hydrate material particles.

[0011] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0012] As a preferred technical solution of the present invention, the impinging stream reactor is provided with a bottom outlet, and the bottom outlet is connected to the feed inlet of the tubular reactor.

[0013] Preferably, the heights of the first side wall inlet and the second side wall inlet are both 45% to 55% of the height of the impinging flow reactor, for example 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54% or 55%, etc., but are not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0014] Preferably, the first side wall inlet and the second side wall inlet have the same height.

[0015] Preferably, inside the impinging stream reactor, the first side wall inlet and the second side wall inlet are respectively provided with a first nozzle and a second nozzle.

[0016] Preferably, the first nozzle and the second nozzle are located on the same straight line in the same horizontal plane.

[0017] Preferably, the calcium-containing solution preparation device and the silicon-containing solution preparation device are both provided with a heating device and a stirring device.

[0018] As a preferred technical solution of the present invention, the tubular reactor includes a reactor shell, on which a feed port and a discharge port are arranged, an internal pipeline connecting the feed port and the discharge port, and a heating device for performing zoned heating on the internal pipeline are arranged inside the reactor shell.

[0019] Preferably, the discharge port of the tubular reactor is connected to a solid-liquid separation device.

[0020] Preferably, the solid-liquid separation device comprises a filtering device and / or a centrifugal device.

[0021] Preferably, the solid-liquid separation device is provided with a solid outlet and a liquid outlet, and the liquid outlet is connected to a secondary crystallization evaporation device.

[0022] Preferably, the feed inlet and the discharge outlet of the tubular reactor are located on the central axis of the tubular reactor.

[0023] As a preferred technical solution of the present invention, the synthesis device further includes a flow control unit, and the flow control unit is connected between the raw material preparation unit and the crystallization reaction unit.

[0024] Preferably, the flow control unit comprises a feeding pump and a venturi tube which are connected in sequence.

[0025] Preferably, the calcium-containing solution preparation device is connected to the first side wall inlet of the impinging flow reactor through a first feeding pump and a first venturi tube which are connected in sequence.

[0026] Preferably, the silicon-containing solution preparation device is connected to the second side wall inlet of the impinging flow reactor through a second feeding pump and a second venturi tube which are connected in sequence.

[0027] In a second aspect, the present invention provides a method for synthesizing nano-hydrated calcium silicate, wherein the method is performed in the synthesis device described in the first aspect, and the method comprises the following steps:

[0028] (1) preparing a calcium-containing solution and a silicon-containing solution respectively;

[0029] (2) sending the calcium-containing solution and the silicon-containing solution obtained in step (1) into an impinging stream reactor to induce nucleation to obtain a mixed slurry;

[0030] (3) sending the mixed slurry obtained in step (2) into a tubular reactor for crystallization reaction to obtain nano calcium silicate hydrate.

[0031] As a preferred technical solution of the present invention, the solute in the calcium-containing solution in step (1) includes any one or a combination of at least two of calcium hydroxide, calcium oxide, calcium chloride, calcium nitrate, calcium bicarbonate, calcium hydrogen sulfate, calcium sulfite, calcium bromide or calcium iodide. Typical but non-limiting examples of the combination include a combination of calcium hydroxide and calcium oxide, a combination of calcium hydroxide and calcium chloride, a combination of calcium hydroxide and calcium nitrate, a combination of calcium hydroxide and calcium bicarbonate, a combination of calcium hydroxide and calcium hydrogen sulfate, a combination of calcium hydroxide and calcium sulfite, a combination of calcium hydroxide and calcium bromide, or a combination of calcium hydroxide and calcium iodide, a combination of calcium oxide and calcium chloride, a combination of calcium oxide and calcium nitrate, a combination of calcium oxide and calcium bicarbonate, a combination of calcium oxide and calcium hydrogen sulfate, a combination of calcium oxide and calcium sulfite, a combination of calcium oxide and calcium bromide, a combination of calcium bicarbonate and calcium hydrogen sulfate, and a combination of calcium bicarbonate and calcium iodide.

[0032] Preferably, the solute in the silicon-containing solution in step (1) includes any one of sodium silicate, silica sol or a silicon-containing solution obtained by alkali desiliconization of solid waste, or a combination of at least two of them. Typical but non-limiting examples of the combination include a combination of sodium silicate and silica sol, a combination of sodium silicate and a silicon-containing solution obtained by alkali desiliconization of solid waste, and a combination of silica sol and a silicon-containing solution obtained by alkali desiliconization of solid waste.

[0033] The silicon-containing solution obtained by alkali desiliconization of solid waste contains sodium silicate, sodium hydroxide and sodium aluminate, wherein the silicon concentration is 5-50 g / L, the sodium concentration is 10-200 g / L, and the aluminum concentration is 0.01-10 g / L.

[0034] Preferably, the concentration of the solute in the calcium-containing solution in step (1) is 0.001-5 mol / L, for example, 0.001 mol / L, 0.003 mol / L, 0.005 mol / L, 0.008 mol / L, 0.01 mol / L, 0.03 mol / L, 0.05 mol / L, 0.08 mol / L, 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, 0.9 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, or 5 mol / L, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are equally applicable.

[0035] Preferably, the concentration of the solute in the silicon-containing solution in step (1) is, for example, 0.001 mol / L, 0.003 mol / L, 0.005 mol / L, 0.008 mol / L, 0.01 mol / L, 0.03 mol / L, 0.05 mol / L, 0.08 mol / L, 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, 0.9 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, or 5 mol / L, but is not limited to the listed values, and other values ​​not listed within the above numerical range are equally applicable.

[0036] As a preferred technical solution of the present invention, step (2) also includes using a flow control unit to control the flow rates of the calcium-containing solution and the silicon-containing solution fed into the impinging stream reactor.

[0037] Preferably, in step (2), the calcium-containing solution is sequentially fed into the impinging stream reactor through a first feeding pump and a first venturi tube.

[0038] Preferably, in step (2), the silicon-containing solution is fed into the impinging stream reactor via a second feeding pump and a second venturi tube in sequence.

[0039] Preferably, the flow rate of the calcium-containing solution fed into the impinging stream reactor is 0.1 to 10 L / min, for example 0.1 L / min, 0.3 L / min, 0.5 L / min, 0.7 L / min, 0.9 L / min, 1 L / min, 2 L / min, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min or 10 L / min, but is not limited to the listed values, and other values ​​not listed within the above numerical range are equally applicable.

[0040] Preferably, the flow rate of the silicon-containing solution fed into the impinging flow reactor is 0.1-10 L / min, for example, 0.1 L / min, 0.3 L / min, 0.5 L / min, 0.7 L / min, 0.9 L / min, 1 L / min, 2 L / min, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min or 10 L / min, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0041] Preferably, the time for inducing nucleation in step (2) is 5 to 300 s, for example 5 s, 6 s, 7 s, 8 s, 9 s, 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, 120 s, 140 s, 160 s, 180 s, 200 s, 220 s, 240 s, 260 s, 280 s or 300 s, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0042] The time for inducing nucleation described in the present invention is a key parameter. If it is too short, the amount of calcium silicate hydrate nanocrystalline nuclei generated is small or even no, while if it is too long, it may cause the material to crystallize and grow prematurely to form large particles or even agglomerate.

[0043] As a preferred technical solution of the present invention, the temperature of the crystallization reaction in step (3) is 25-300°C, for example, 25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, 220°C, 240°C, 280°C or 300°C, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0044] In the present invention, the crystallization temperature mainly affects the crystal structure of the synthesized material. Under low temperature conditions, the material may exist in the form of calcium silicate hydrate with low crystallinity, while high temperature may form calcium silicate hydrate with high crystallinity, but it may also produce impurities, which needs to be reasonably determined according to the desired product type.

[0045] Preferably, the residence time of the mixed slurry in step (3) in the tubular reactor is 0.2 to 12 h, for example, 0.2 h, 0.4 h, 0.6 h, 0.8 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h or 12 h, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0046] Preferably, after the crystallization reaction in step (3) is completed, solid-liquid separation is performed to obtain a liquid product and nano-calcium silicate hydrate.

[0047] Preferably, the solid-liquid separation comprises filtering in a filtering device.

[0048] Preferably, the liquid product is sent to a secondary crystallization evaporation device for recycling.

[0049] As a preferred technical solution of the present invention, the synthesis method comprises the following steps:

[0050] (1) In a calcium-containing solution preparation device and a silicon-containing solution preparation device of a raw material preparation unit, a calcium-containing solution and a silicon-containing solution with concentrations of 0.001 to 5 mol / L and 0.001 to 5 mol / L are prepared respectively;

[0051] (2) allowing the calcium-containing solution obtained in step (1) to pass through a first feeding pump and a first venturi tube in sequence, and to be fed into an impinging flow reactor from a first side wall inlet at a flow rate of 0.1 to 10 L / min, while allowing the silicon-containing solution obtained in step (1) to pass through a second feeding pump and a second venturi tube in sequence, and to be fed into an impinging flow reactor from a second side wall inlet at a flow rate of 0.1 to 10 L / min, and inducing nucleation for 5 to 300 seconds to obtain a mixed slurry;

[0052] (3) The mixed slurry obtained in step (2) is placed in a tubular reactor, subjected to a crystallization reaction at 25 to 300° C. for 0.2 to 12 hours, and then sent to a filtration device for filtration to obtain a liquid product and nano-calcium silicate hydrate, and the liquid product is sent to a secondary crystallization evaporation device for recycling.

[0053] In a third aspect, the present invention provides a nano calcium silicate hydrate, which is prepared using the synthesis device described in the first aspect or the synthesis method described in the second aspect.

[0054] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0055] The synthesis device of the present invention can effectively solve the particle agglomeration problem during the production of nano calcium silicate hydrate, does not need to use medicaments, does not cause environmental pollution, and can realize the efficient regulation and synthesis of nano calcium silicate hydrate. The raw material preparation unit can effectively regulate the raw material concentration components, and the flow control unit can realize accurate control according to the production capacity and crystallization efficiency. The crystallization reaction unit can realize the rapid induction of nucleation and crystal growth of nano calcium silicate hydrate particles, realize the continuous production and synthesis of nano calcium silicate hydrate, which is conducive to further improving the production efficiency and has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1is a schematic diagram of a synthesis device for nano-hydrated calcium silicate provided in Example 1;

[0057] In the figure: 1-calcium-containing solution preparation tank, 2-first feeding pump, 3-first venturi tube, 4-silicon-containing solution preparation tank, 5-second feeding pump, 6-second venturi tube, 7-impinging flow reactor, 8-tubular reactor, 9-centrifugal separation device, 10-first side wall inlet, 11-second side wall inlet, 12-bottom outlet. DETAILED DESCRIPTION

[0058] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention, and the scope of protection of the present invention shall be subject to the claims.

[0060] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0061] Example 1

[0062] This embodiment provides a synthesis device for nano calcium silicate hydrate, the schematic diagram of which is shown in FIG. Figure 1 As shown, the synthesis device includes a raw material preparation unit, a flow control unit and a crystallization reaction unit connected in sequence along the material flow direction;

[0063] The raw material preparation unit comprises a calcium-containing solution preparation tank 1 and a silicon-containing solution preparation tank 4; the calcium-containing solution preparation tank 1 and the silicon-containing solution preparation tank 4 are both provided with a heating device and a stirring device;

[0064] The flow control unit includes a feeding pump and a venturi tube connected in sequence, the calcium-containing solution preparation tank 1 is connected to the first feeding pump 2, and the first feeding pump 2 is connected to the first venturi tube 3; the silicon-containing solution preparation tank 4 is connected to the second feeding pump 5, and the second feeding pump 5 is connected to the second venturi tube 6;

[0065] The crystallization reaction unit comprises an impinging stream reactor 7 and a tubular reactor 8, wherein the impinging stream reactor 7 is provided with a first side wall inlet 10, a second side wall inlet 11 and a bottom outlet 12 in opposite relation; the height of the first side wall inlet 10 and the second side wall inlet 11 are both 50% of the height of the impinging stream reactor 7; the first venturi tube 3 is connected to the first side wall inlet 10, and the second venturi tube 6 is connected to the second side wall inlet 11; inside the impinging stream reactor, the first side wall inlet and the second side wall inlet are provided with a first nozzle and a second nozzle respectively; the first nozzle and the second nozzle are located on the same straight line on the same horizontal plane;

[0066] The tubular reactor 8 comprises a reactor shell, on which a feed port and a discharge port are arranged, the feed port and the discharge port are located on the central axis of the tubular reactor, the bottom outlet 12 is connected to the feed port of the tubular reactor 8, and an internal pipeline connecting the feed port and the discharge port, as well as a heating device for performing zone heating on the internal pipeline, are arranged inside the reactor shell;

[0067] The discharge port of the tubular reactor 8 is connected to the centrifugal separation device 9. The filtering device is provided with a solid outlet and a liquid outlet. The liquid outlet is connected to the secondary crystallization evaporation device.

[0068] In the synthesis device provided in this embodiment, the first feeding pump 2 pumps the calcium-containing solution from the calcium-containing solution preparation tank 1 into the first venturi tube 3, and sprays it into the impinging flow reactor 7 through the first nozzle; the second feeding pump 5 pumps the silicon-containing solution from the silicon-containing solution preparation tank 4 into the second venturi tube 6, and sprays it into the impinging flow reactor 7 through the second nozzle; the calcium-containing solution and the silicon-containing solution undergo rapid collision in the impinging flow reactor 7 to induce nucleation, and naturally and smoothly flow into the tubular reactor 8 to complete the crystallization reaction. After the reaction is completed, the mixed slurry is sent to the centrifugal separation device 9 for solid-liquid separation.

[0069] Comparative Example 1

[0070] This comparative example provides a synthesis device for nano-hydrated calcium silicate, in which the impinging stream reactor is replaced by a conventional reaction container, so that the calcium-containing solution and the silicon-containing solution are mixed only in the reaction container. Apart from this, other conditions are exactly the same as those in Example 1.

[0071] Application Example 1

[0072] This application example provides a method for synthesizing nano calcium silicate hydrate, which is carried out in the synthesis device provided in Example 1, and comprises the following steps:

[0073] (1) In the calcium-containing solution preparation device and the silicon-containing solution preparation device of the raw material preparation unit, a calcium-containing solution (calcium hydroxide solution) and a silicon-containing solution (sodium silicate solution) with concentrations of 0.1 mol / L and 0.1 mol / L are prepared respectively;

[0074] (2) the calcium-containing solution obtained in step (1) is sequentially passed through a first feeding pump and a first venturi tube, and fed into an impinging flow reactor from a first side wall inlet at a flow rate of 5 L / min. At the same time, the silicon-containing solution obtained in step (1) is sequentially passed through a second feeding pump and a second venturi tube, and fed into an impinging flow reactor from a second side wall inlet at a flow rate of 5 L / min. The calcium-containing solution and the silicon-containing solution are rapidly collided and mixed, and induced nucleation is performed for 200 seconds to obtain a mixed slurry;

[0075] (3) The mixed slurry obtained in step (2) is placed in a tubular reactor, subjected to a crystallization reaction at 210° C. for 3 hours, and then sent to a filtration device for filtration to obtain a liquid product and nano-calcium silicate hydrate, and the liquid product is sent to a secondary crystallization evaporation device for recycling.

[0076] Application Example 2

[0077] This application example provides a method for synthesizing nano calcium silicate hydrate, which is carried out in the synthesis device provided in Example 1, and comprises the following steps:

[0078] (1) In the calcium-containing solution preparation device and the silicon-containing solution preparation device of the raw material preparation unit, prepare a calcium-containing solution (calcium chloride solution) and a silicon-containing solution (silica sol, source leaf biological, reagent grade 30%) with a concentration of 0.1 mol / L and 0.1 mol / L respectively;

[0079] (2) allowing the calcium-containing solution obtained in step (1) to pass through a first feeding pump and a first venturi tube in sequence, and to be fed into an impinging flow reactor from a first side wall inlet at a flow rate of 0.1 L / min; and allowing the silicon-containing solution obtained in step (1) to pass through a second feeding pump and a second venturi tube in sequence, and to be fed into an impinging flow reactor from a second side wall inlet at a flow rate of 0.1 L / min, the calcium-containing solution and the silicon-containing solution are rapidly collided and mixed, and induced nucleation is performed for 500 s to obtain a mixed slurry;

[0080] (3) The mixed slurry obtained in step (2) is placed in a tubular reactor, subjected to a crystallization reaction at 250° C. for 0.2 h, and then sent to a filtration device for filtration to obtain a liquid product and nano-calcium silicate hydrate, and the liquid product is sent to a secondary crystallization evaporation device for recycling.

[0081] Application Example 3

[0082] This application example provides a method for synthesizing nano calcium silicate hydrate, which is carried out in the synthesis device provided in Example 1, and comprises the following steps:

[0083] (1) In the calcium-containing solution preparation device and the silicon-containing solution preparation device of the raw material preparation unit, a calcium-containing solution (calcium nitrate solution) and a silicon-containing solution (silicon-containing solution obtained by alkali desiliconization of solid waste) with concentrations of 0.1 mol / L and 0.1 mol / L are prepared respectively; the silicon-containing solution obtained by alkali desiliconization of solid waste is derived from the silicon-containing solution obtained by alkali desiliconization of high-aluminum fly ash from the Tuoketuo coal-fired power plant in Inner Mongolia, and its components are: sodium silicate, sodium hydroxide, and sodium aluminate.

[0084] (2) allowing the calcium-containing solution obtained in step (1) to pass through a first feeding pump and a first venturi tube in sequence, and to be fed into an impinging flow reactor from a first side wall inlet at a flow rate of 10 L / min; and allowing the silicon-containing solution obtained in step (1) to pass through a second feeding pump and a second venturi tube in sequence, and to be fed into an impinging flow reactor from a second side wall inlet at a flow rate of 10 L / min; the calcium-containing solution and the silicon-containing solution are rapidly collided and mixed, and induced nucleation is performed for 300 seconds to obtain a mixed slurry;

[0085] (3) The mixed slurry obtained in step (2) is placed in a tubular reactor, subjected to a crystallization reaction at 300° C. for 12 hours, and then sent to a filtration device for filtration to obtain a liquid product and nano-hydrated calcium silicate. The liquid product is sent to a secondary crystallization evaporation device for recycling.

[0086] Application Example 4

[0087] This application example provides a method for synthesizing nano-calcium silicate hydrate. Except for adjusting the flow rate of the calcium-containing solution in step (2) from 5 L / min to 0.05 L / min, other conditions are exactly the same as those in Application Example 1.

[0088] Application Example 5

[0089] This application example provides a method for synthesizing nano-hydrated calcium silicate. Except for adjusting the flow rate of the calcium-containing solution in step (2) from 5 L / min to 0.1 L / min, other conditions are exactly the same as those in Application Example 1.

[0090] Application Example 6

[0091] This application example provides a method for synthesizing nano-calcium silicate hydrate. Except for adjusting the flow rate of the calcium-containing solution in step (2) from 5 L / min to 2 L / min, other conditions are exactly the same as those in Application Example 1.

[0092] Application Example 7

[0093] This application example provides a method for synthesizing nano-calcium silicate hydrate. Except for adjusting the flow rate of the calcium-containing solution in step (2) from 5 L / min to 8 L / min, other conditions are exactly the same as those in Application Example 1.

[0094] Application Example 8

[0095] This application example provides a method for synthesizing nano-calcium silicate hydrate. Except for adjusting the flow rate of the calcium-containing solution in step (2) from 5 L / min to 10 L / min, other conditions are exactly the same as those in Application Example 1.

[0096] Application Example 9

[0097] This application example provides a method for synthesizing nano-calcium silicate hydrate. Except for adjusting the flow rate of the calcium-containing solution in step (2) from 5 L / min to 10.5 L / min, other conditions are exactly the same as those in Application Example 1.

[0098] Application Example 10

[0099] This application example provides a method for synthesizing nano-calcium silicate hydrate. Except that the time for inducing nucleation in step (2) is adjusted from 200 s to 2 s, other conditions are exactly the same as those in application example 1.

[0100] Application Example 11

[0101] This application example provides a method for synthesizing nano-calcium silicate hydrate. Except that the time for inducing nucleation in step (2) is adjusted from 200 s to 5 s, other conditions are exactly the same as those in application example 1.

[0102] Application Example 12

[0103] This application example provides a method for synthesizing nano-calcium silicate hydrate. Except that the time for inducing nucleation in step (2) is adjusted from 200 s to 50 s, other conditions are exactly the same as those in application example 1.

[0104] Application Example 13

[0105] This application example provides a method for synthesizing nano-calcium silicate hydrate. Except that the time for inducing nucleation in step (2) is adjusted from 200 s to 100 s, other conditions are exactly the same as those in application example 1.

[0106] Application Example 14

[0107] This application example provides a method for synthesizing nano-calcium silicate hydrate. Except that the time for inducing nucleation in step (2) is adjusted from 200 s to 300 s, other conditions are exactly the same as those in application example 1.

[0108] Application Example 15

[0109] This application example provides a method for synthesizing nano-calcium silicate hydrate. Except that the time for inducing nucleation in step (2) is adjusted from 200 s to 310 s, other conditions are exactly the same as those in application example 1.

[0110] Application Comparative Example 1

[0111] This application comparative example provides a method for synthesizing nano calcium silicate hydrate, which is carried out in the synthesis device provided in comparative example 1, and comprises the following steps:

[0112] (1) In the calcium-containing solution preparation device and the silicon-containing solution preparation device of the raw material preparation unit, a calcium-containing solution (calcium hydroxide solution) and a silicon-containing solution (sodium silicate solution) with concentrations of 0.1 mol / L and 0.1 mol / L are prepared respectively;

[0113] (2) the calcium-containing solution obtained in step (1) is sequentially passed through a first feeding pump and a first venturi tube, and fed into a reaction container from a first side wall inlet at a flow rate of 5 L / min. At the same time, the silicon-containing solution obtained in step (1) is sequentially passed through a second feeding pump and a second venturi tube, and fed into the reaction container from a second side wall inlet at a flow rate of 5 L / min. The calcium-containing solution and the silicon-containing solution are not collided, and are only mixed in the reaction container for 200 seconds to obtain a mixed slurry;

[0114] (3) The mixed slurry obtained in step (2) is placed in a tubular reactor, subjected to a crystallization reaction at 210° C. for 3 hours, and then sent to a filtration device for filtration to obtain a liquid product and nano-calcium silicate hydrate, and the liquid product is sent to a secondary crystallization evaporation device for recycling.

[0115] The nano-hydrated calcium silicate obtained in Application Examples 1-15 and Application Comparative Example 1 was tested using a laser particle size analyzer from Malvern Instruments of the United Kingdom as the testing equipment. The dynamic light scattering method was used to obtain the particle size value at a measuring angle θ of 173°, a sample cell temperature of 30°C, and a laser wavelength of 633nm. The results are recorded in Table 1.

[0116] Table 1

[0117]

[0118]

[0119] It can be seen from Table 1 that:

[0120] (1) Comprehensive application examples 1 to 3 show that the synthesis method of nano calcium silicate hydrate provided by the present invention can make the silicon conversion rate ≥ 99.3%, the calcium silicate hydrate particle size ≤ 19.2nm, and the dispersion degree ≥ 98.0%;

[0121] (2) Comprehensive application examples 4 to 9 show that when the flow rate of the calcium-containing solution fed into the impinging stream reactor increases, the silicon conversion rate can be promoted from 89.6% to 99.2%, the particle size of the calcium silicate hydrate product particles decreases from 28.5nm to 22.1nm, and the dispersion increases from 91.2% to 98.1%. However, when the calcium flow rate is too high, the particle size of the calcium silicate hydrate product increases to 28.8nm, and the dispersion decreases to 91.4%, indicating that both too low and too high calcium flow rates have an adverse effect on the synthesis of nano calcium silicate.

[0122] (3) It can be seen from the application examples 10 to 15 and the comparative application example 1 that when the induction nucleation time in the impinging stream reactor increases, the silicon conversion rate can be promoted to increase from 88.6% to 98.7%, the particle size of the calcium silicate hydrate product particles decreases from 23.7nm to 19.0nm, and the dispersion increases from 93.6% to 98.2%. However, too long an induction time causes the calcium silicate hydrate particle size to increase to 23.7nm and the dispersion decreases to 93.1%, indicating that too short or too long an induction time in the impinging stream reactor will cause a certain degree of agglomeration effect of the calcium silicate hydrate; in addition, if the impinging stream reactor is not used for the crystallization reaction, the silicon conversion rate is ≤82.3%, the calcium silicate hydrate particle size is ≥38.9nm, and the dispersion is ≥78.5%, indicating that the impinging stream reactor has a significant improvement effect on the silicon conversion rate and dispersion during the synthesis of nano calcium silicate hydrate.

[0123] Therefore, the synthesis device and the synthesis method of the present invention can effectively solve the particle agglomeration problem during the production of nano calcium silicate hydrate, realize the rapid induction of nucleation and crystal growth of nano calcium silicate hydrate particles, promote the continuous production and synthesis of nano calcium silicate hydrate, and are conducive to further improving production efficiency, and have good industrial application prospects.

[0124] The present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0125] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0126] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0127] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for synthesizing nano-hydrated calcium silicate, characterized in that: The synthesis method is carried out in a synthesis device, which comprises a raw material preparation unit and a crystallization reaction unit connected in sequence along the material flow direction; the raw material preparation unit comprises a calcium-containing solution preparation device and a silicon-containing solution preparation device; the crystallization reaction unit comprises an impinging stream reactor and a tubular reactor connected in sequence; a first side wall inlet and a second side wall inlet are arranged oppositely on the impinging stream reactor, the calcium-containing solution preparation device is connected to the first side wall inlet, and the silicon-containing solution preparation device is connected to the second side wall inlet; The synthesis method comprises the following steps: (1) In a calcium-containing solution preparation device and a silicon-containing solution preparation device of a raw material preparation unit, respectively preparing a calcium-containing solution and a silicon-containing solution with a concentration of 0.001 to 5 mol / L; (2) feeding the calcium-containing solution obtained in step (1) into the impinging stream reactor from the first side wall inlet at a flow rate of 0.1 to 10 L / min, and simultaneously feeding the silicon-containing solution into the impinging stream reactor from the second side wall inlet at a flow rate of 0.1 to 10 L / min, and inducing nucleation for 5 to 300 seconds to obtain a mixed slurry; (3) The mixed slurry obtained in step (2) is fed into a tubular reactor and subjected to a crystallization reaction at 25 to 300° C. for 0.2 to 12 hours to obtain nano-hydrated calcium silicate.

2. The synthesis method according to claim 1, characterized in that The impinging flow reactor is provided with a bottom outlet, and the bottom outlet is connected to the feed inlet of the tubular reactor.

3. The synthesis method according to claim 1, characterized in that The heights of the first side wall inlet and the second side wall inlet are both 45% to 55% of the height of the impinging stream reactor.

4. The synthesis method according to claim 3, characterized in that The first side wall inlet and the second side wall inlet have the same height.

5. The synthesis method according to claim 1, characterized in that Inside the impinging stream reactor, the first side wall inlet and the second side wall inlet are respectively provided with a first nozzle and a second nozzle.

6. The synthesis method according to claim 5, characterized in that The first nozzle and the second nozzle are located on the same straight line in the same horizontal plane.

7. The synthesis method according to claim 1, characterized in that The calcium-containing solution preparation device and the silicon-containing solution preparation device are both provided with a heating device and a stirring device.

8. The synthesis method according to claim 1, characterized in that The tubular reactor comprises a reactor shell, on which a feed port and a discharge port are arranged, an internal pipeline connecting the feed port and the discharge port, and a heating device for performing zoned heating on the internal pipeline are arranged inside the reactor shell.

9. The synthesis method according to claim 8, characterized in that The discharge port of the tubular reactor is connected to a solid-liquid separation device.

10. The synthesis method according to claim 9, characterized in that The solid-liquid separation device includes a filtering device and / or a centrifugal device.

11. The synthesis method according to claim 9, characterized in that The solid-liquid separation device is provided with a solid outlet and a liquid outlet, and the liquid outlet is connected to a secondary crystallization evaporation device.

12. The synthesis method according to claim 8, characterized in that The feed inlet and the discharge outlet of the tubular reactor are located on the central axis of the tubular reactor.

13. The synthesis method according to claim 1, characterized in that: The synthesis device further comprises a flow control unit, which is connected between the raw material preparation unit and the crystallization reaction unit.

14. The synthesis method according to claim 13, characterized in that: The flow control unit comprises a feeding pump and a venturi tube which are connected in sequence.

15. The synthesis method according to claim 14, characterized in that: The calcium-containing solution preparation device is connected to the first side wall inlet of the impinging flow reactor through a first feeding pump and a first venturi tube which are connected in sequence.

16. The synthesis method according to claim 14, characterized in that: The silicon-containing solution preparation device is connected to the second side wall inlet of the impinging flow reactor through a second feeding pump and a second venturi tube which are connected in sequence.

17. The synthesis method according to claim 1, characterized in that: The solute in the calcium-containing solution in step (1) includes any one of calcium hydroxide, calcium oxide, calcium chloride, calcium nitrate, calcium bicarbonate, calcium bisulfate, calcium sulfite, calcium bromide or calcium iodide, or a combination of at least two thereof.

18. The synthesis method according to claim 1, characterized in that: The solute in the silicon-containing solution in step (1) includes any one of sodium silicate, silica sol or a silicon-containing solution obtained by alkali desiliconization of solid waste, or a combination of at least two of them.

19. The synthesis method according to claim 13, characterized in that: Step (2) also includes using a flow control unit to control the flow rates of the calcium-containing solution and the silicon-containing solution fed into the impinging stream reactor.

20. The synthesis method according to claim 15, characterized in that: In step (2), the calcium-containing solution is sequentially fed into the impinging flow reactor through a first feeding pump and a first venturi tube.

21. The synthesis method according to claim 16, characterized in that: In step (2), the silicon-containing solution is sequentially fed into the impinging flow reactor through a second feeding pump and a second venturi tube.

22. The synthesis method according to claim 11, characterized in that: After the crystallization reaction in step (3) is completed, solid-liquid separation is performed to obtain a liquid product and nano-calcium silicate hydrate; the liquid product is sent to a secondary crystallization evaporation device for recycling.

23. The synthesis method according to claim 1, characterized in that The synthesis method comprises the following steps: (1) In a calcium-containing solution preparation device and a silicon-containing solution preparation device of a raw material preparation unit, a calcium-containing solution and a silicon-containing solution with concentrations of 0.001 to 5 mol / L and 0.001 to 5 mol / L are prepared respectively; (2) allowing the calcium-containing solution obtained in step (1) to pass through a first feeding pump and a first venturi tube in sequence, and to be fed into an impinging flow reactor from a first side wall inlet at a flow rate of 0.1 to 10 L / min, while allowing the silicon-containing solution obtained in step (1) to pass through a second feeding pump and a second venturi tube in sequence, and to be fed into an impinging flow reactor from a second side wall inlet at a flow rate of 0.1 to 10 L / min, and inducing nucleation for 5 to 300 seconds to obtain a mixed slurry; (3) The mixed slurry obtained in step (2) is placed in a tubular reactor, subjected to a crystallization reaction at 25 to 300° C. for 0.2 to 12 hours, and then sent to a filtration device for filtration to obtain a liquid product and nano-calcium silicate hydrate, and the liquid product is sent to a secondary crystallization evaporation device for recycling.

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