Method for preparing aragonite whiskers through high-speed CO2 flow field synergistic mineralization of solid waste and product

Abstract

The invention discloses a method for preparing aragonite whiskers through high-speed CO2 flow field synergistic mineralization of solid waste and a product, and belongs to the technical field of solid waste recycling and inorganic functional material preparation. According to the method, industrial solid waste containing Ca < 2 + > and Mg < 2 + > serves as a raw material, the temperature is increased to be larger than or equal to 60 DEG C after leaching, a crystal form regulator and a dispersing agent are added, blowing mineralization is conducted on the solution through high-speed CO2 airflow, and oriented growth of the aragonite whiskers is achieved through the shear enhanced mass transfer effect of a flow field and the cooperative regulation effect of an additive. According to the method, the technical bottlenecks of low aragonite phase purity, easiness in whisker agglomeration and high raw material cost in traditional aragonite whisker preparation are overcome, a high-speed CO2 flow field is innovatively introduced into a solid waste mineralization system, and the CO2 mass transfer efficiency and whisker morphology controllability are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization and inorganic functional material preparation technology, specifically involving a method and product for preparing aragonite whiskers by synergistic mineralization of solid waste using a high-speed CO2 flow field. Background Technology

[0002] Aragonite whiskers, as a high-performance inorganic material, have significant application value in composite materials, environmental adsorption, and other fields. Traditional preparation methods mainly include chemical reagent synthesis and mineralization. Chemical methods have high raw material costs and are difficult to treat waste liquid; although mineralization methods have environmental advantages, they mostly adopt static or mechanical stirring modes, which have the following prominent problems: 1. Low CO2 mass transfer efficiency: In static mineralization, CO2 depends on natural diffusion, the mass transfer rate is slow, and there are concentration gradients and reaction dead zones in the reaction system, resulting in incomplete mineralization, low aragonite phase purity (usually <70%), and easy formation of calcite, aragonite, and other heteromorphic crystals. 2. Poor controllability of whisker morphology: Although mechanical stirring can enhance mixing, its shear force is random and uneven, which easily destroys the directional growth structure of whiskers, resulting in wide whisker diameter distribution, low aspect ratio, and easy agglomeration. 3. Weak adaptability of solid waste-based systems: Existing solid waste mineralization processes mostly use static CO2 passage methods directly, without designing enhanced mass transfer methods to address the characteristics of large fluctuations in ion concentration and numerous impurities in solid waste leachate. This results in low whisker purity and poor morphology, making it difficult to meet the needs of high-end applications.

[0003] In recent years, although some studies have attempted to enhance CO2 mass transfer through pressurization and microbubbles, problems such as complex equipment, high energy consumption, and difficulty in scaling up still exist. In particular, how to introduce fluid dynamics effects into solid waste mineralization systems and achieve integrated control of mass transfer, reaction, and morphology through flow field design remains a technical challenge that has not yet been overcome in this field. Summary of the Invention

[0004] The main objective of this invention is to provide a method and product for preparing aragonite whiskers by synergistic mineralization of solid waste using a high-speed CO2 flow field. The technical problems to be solved are the high cost of raw materials, low purity of the aragonite phase, easy agglomeration of whiskers, poor performance of solid waste-based aragonite whiskers, and low CO2 mineralization mass transfer efficiency in traditional aragonite whisker preparation methods. This invention proposes an integrated solution involving high-speed CO2 flow field-driven mineralization, the substitution of pure chemical reagents with calcium and magnesium sources from solid waste, and the synergistic regulation of crystal form by additives. This simultaneously achieves the technical goals of high-value resource utilization of solid waste, efficient industrial CO2 storage, and the directional preparation of high-purity aragonite whiskers.

[0005] The technical solution of this invention is: a method for preparing aragonite whiskers by synergistic mineralization of solid waste using a high-speed CO2 flow field, comprising: 1) Containing Ca 2+ and Mg 2+ The solid waste raw materials are dried, crushed, sieved, and then leached with water to obtain a calcium-magnesium mixed solution. 2) Heat the calcium-magnesium mixed solution to a specified temperature and keep it therein, then add the compound additive and stir until completely dissolved; 3) A high-speed CO2 gas flow with a velocity of 10-50 m / s is introduced into the additive-mixed solution system obtained in step 2). The gas flow creates a turbulent flow field, which facilitates the mineralization reaction. 4) After the reaction is complete, aragonite whiskers are obtained by solid-liquid separation and drying.

[0006] The Ca-containing 2+ and Mg 2+ The solid waste raw materials are selected from at least one of magnesium slag, steel slag, and construction waste residue. In this invention, the use of solid wastes such as magnesium slag, steel slag, and construction waste residue can provide natural Ca for the mineralization reaction. 2+ and Mg 2+ This method not only achieves solid waste disposal but also replaces pure chemical reagents, reducing raw material costs. The raw material ratio is designed based on the calcium and magnesium content of different solid wastes. Magnesium slag and steel slag can serve as highly active calcium and magnesium sources, providing sufficient reaction ions. The silicate mineral components in construction waste residue can adsorb free water in the solution, providing a stable microenvironment for the CO2 mineralization reaction and improving CO2 solidification efficiency and whisker growth stability. During the high-speed CO2 flow field mineralization process, CO2 reacts with Ca in the solution... 2+ and Mg 2+ A directional mineralization reaction occurs, forming aragonite whiskers with a high aspect ratio. Furthermore, trace amounts of silicon and aluminum impurities in the solid waste can help regulate the surface morphology of the whiskers, enhancing their suitability for subsequent applications.

[0007] The compounded additives include crystal form regulators and dispersant additives. The crystal form regulator is selected from at least one of sodium citrate and disodium ethylenediaminetetraacetate (EDTA-2Na), and the dispersant additive is selected from at least one of low molecular weight sodium polyacrylate and polyethylene glycol. In this invention, the combination of crystal form regulators and dispersant additives forms a modification and control system, which plays a role in inducing crystal orientation and stabilizing whisker dispersion, significantly improving the crystal purity and morphological uniformity of aragonite whiskers. Crystal form regulators such as sodium citrate and EDTA-2Na can react with Ca... 2+ Forming a weak complex structure to achieve Ca 2+ The slow release avoids the formation of heteromorphic crystals such as calcite due to a sudden increase in ion concentration, while simultaneously reacting with Mg in the solid waste. 2+ The two work together to enhance the directional formation of aragonite crystals; low molecular weight sodium polyacrylate can be adsorbed on the surface of the initial crystal nuclei of the whiskers, weakening the agglomeration force of the crystal nuclei, while polyethylene glycol achieves precise control of the pore size and aspect ratio of the whiskers through its chain structure. The two work together to ensure the dispersion and integrity of the whiskers.

[0008] The CO2 gas is industrial-grade carbon dioxide or industrial flue gas containing CO2 (CO2 concentration ≥ 99.99%), selected from at least one of cement kiln tail gas, glass kiln tail gas, and chemical reactor tail gas (CO2 concentration ≥ 20%). This invention does not specify a particular pressure for CO2 mineralization because a high-speed CO2 flow field can significantly enhance the mass transfer efficiency of CO2 in solution, and the synergistic effect of the additives provides a stable environment for aragonite whisker growth. High-purity whiskers can be prepared without a high-pressure sealing device, reducing equipment investment and facilitating continuous production.

[0009] In step 1), the solid waste raw material is dried at a temperature of 100-120℃ for 2-4 hours. After crushing, it is passed through a 100-200 mesh sieve. The calcium-magnesium mixed solution contains Ca... 2+ and Mg 2+ The molar ratio is 1:(0.2-0.8). According to the present invention, the drying and pulverizing process removes excess moisture and surface impurities from the solid waste, enhances the leaching activity of calcium and magnesium components in the solid waste, and the precise control of the calcium-magnesium molar ratio is a core prerequisite for ensuring the stable formation of aragonite crystals. 2+ It can be adsorbed on the active sites of calcite crystal growth, hindering its crystal transformation and promoting the directional development of aragonite crystal nuclei.

[0010] In step 1), the solid-liquid ratio of the solid waste raw material to deionized water is 1:(10-30), the leaching stirring speed is 200-300 r / min, and the leaching time is 1-2 h. Limiting the solid-liquid ratio and stirring parameters ensures sufficient leaching of calcium and magnesium components from the solid waste, while avoiding excessively low ion concentration due to an excessively high solid-liquid ratio, or excessively broken solid waste particles due to excessive stirring, introducing excessive impurities, thus providing a stable ion system for subsequent mineralization reactions.

[0011] In step 2), the temperature of the mixed solution is maintained at 60-80℃, the total amount of compound additives added is 0.05-0.5% of the total mass of the mixed solution, and the mass ratio of crystal form regulator to dispersant additive is 1:(0.5-1). The temperature range of 60-80℃ can improve the dissolution rate and ionic reactivity of CO2 in the solution, and also ensure the thermodynamic stability of the aragonite crystal form, inhibiting the formation of unstable impurities such as aragonite; the amount and ratio of additives achieve a balance between crystal form regulation and dispersion stability. Excessive addition will lead to additive residue on the surface of the whiskers, while insufficient addition will not play an effective regulatory role.

[0012] In step 3), the flow rate of the high-speed CO2 gas is 10-50 m / s, and the mineralization reaction time is 2-6 h. The high-speed CO2 gas flow of 10-50 m / s can form a stable turbulent flow field in the solution, which on the one hand enhances the mass transfer depth of CO2 in the solution and eliminates the reaction dead zone of static mineralization, and on the other hand guides the aragonite whiskers to grow directionally along the gas flow direction through the shear force of the flow field, thereby controlling the whisker diameter and aspect ratio; the reaction time of 2-6 h can ensure sufficient ion mineralization, while avoiding morphological distortion caused by excessive whisker growth due to excessive reaction time.

[0013] The high-speed CO2 gas flow is introduced into the solution in a turbulent manner through a nozzle or gas distributor, thereby enhancing the flow field shearing and mass transfer of the solution.

[0014] In step 4), solid-liquid separation is achieved using vacuum filtration at a pressure of 0.05-0.08 MPa, a drying temperature of 60-80℃, and a drying time of 2-4 hours. Vacuum filtration can quickly achieve solid-liquid separation, reducing secondary agglomeration of whiskers in the liquid phase, while medium-low temperature drying ensures that the crystal structure of the aragonite whiskers is not damaged, maintaining its excellent physicochemical properties.

[0015] The prepared aragonite whiskers have an aragonite phase content of ≥90%, a diameter of 5-20μm, and an adjustable aspect ratio, making them suitable for applications such as composite material reinforcement, environmental adsorption, and paper filling.

[0016] By employing the above technical solution, the present invention has at least the following advantages: 1. In this invention, industrial solid waste such as magnesium slag, steel slag, and construction waste residue are used as calcium and magnesium ion sources. After drying at 100-120℃ and grinding with 100-200 mesh, the calcium and magnesium components can be efficiently leached. Each ton of aragonite whiskers can consume 0.8-1.2 tons of solid waste, which greatly improves the level of high-value utilization of solid waste and reduces the environmental risks of solid waste storage.

[0017] 2. This invention adopts an innovative technical solution of synergistic regulation of high-speed CO2 flow field and additives. The high-speed CO2 airflow can form a turbulent flow field to enhance mass transfer. Combined with the directional induction of crystal form regulator and the agglomeration inhibition of dispersant, the proportion of aragonite phase is increased to more than 90%, the whisker diameter is stabilized at 5-20μm, the aspect ratio reaches 20-50:1, and there is no obvious agglomeration or impure crystal form, which is significantly better than traditional solid waste-based aragonite whisker products.

[0018] 3. This invention does not require a high-pressure sealed mineralization device. High-efficiency mineralization can be achieved in a normal pressure high-speed CO2 flow field, eliminating the cost and safety risks of periodic inspection of pressure vessels. At the same time, the mineralization reaction time is shortened by 30%-50% compared with the traditional static process, reducing production energy consumption and facilitating large-scale continuous production.

[0019] 4. This invention uses solid waste calcium and magnesium sources to replace pure chemical reagents. The cost of preparing each ton of aragonite whisker raw material by traditional chemical reagent methods exceeds 8,000 yuan, while the cost of each ton of raw material prepared by this invention can be reduced to less than 3,000 yuan, a reduction of more than 60%. At the same time, it uses industrial CO2 flue gas as a mineralized carbon source, and each ton of aragonite whisker can seal 0.3-0.5 tons of CO2, realizing the integration of solid waste disposal and low-carbon preparation, achieving resource carbon neutrality and negative carbon manufacturing throughout the entire process from the source. Detailed Implementation

[0020] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the present invention will be described in detail below with reference to preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0021] The present invention will be further described below with reference to specific embodiments, but this should not be construed as a limitation on the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0022] In the following embodiments of the present invention, unless otherwise specified, all reagents used are commercially available, and all methods involved are conventional methods.

[0023] The present invention discloses a method for preparing aragonite whiskers by synergistic mineralization of solid waste using a high-speed CO2 flow field, comprising the following steps: 1) Containing Ca 2+ and Mg 2+ The solid waste raw materials are crushed and then prepared into a mixed solution; 2) Control the temperature of the mixed solution at ≥60℃, add the compound additive, and stir until completely dissolved; 3) A high-speed CO2 gas flow is introduced into the solution of step 2), and the high-speed gas flow is used to blow the solution to carry out a mineralization reaction; 4) After the reaction is complete, the solid and liquid are separated and dried to obtain aragonite whiskers.

[0024] This invention proposes and constructs a high-speed CO2 flow field synergistic mineralization system for the first time. By blowing the solution with a high-speed airflow (10-50 m / s), a high-intensity turbulent field is formed, achieving the following multiple enhancement effects: 1. Enhanced mass transfer: The high-speed CO2 airflow significantly increases the gas-liquid interface renewal rate, enhancing CO2 dissolution and ion diffusion efficiency; 2. Flow field shear regulation: Controllable flow field shear force guides the directional alignment and growth of aragonite nuclei, inhibiting agglomeration; 3. Reaction homogenization: The turbulent field eliminates reaction dead zones, ensuring uniform ion spatial distribution and improving the completeness of the mineralization reaction.

[0025] This method significantly improves the purity and morphological controllability of aragonite whiskers, achieving high-value mineralization under normal pressure conditions. It is both engineering feasible and economical, and has significant technological innovation and industrial application value.

[0026] Example 1 This invention provides a method for preparing aragonite whiskers by synergistic mineralization of solid waste using a high-speed CO2 flow field, the specific steps of which are as follows: 1) Magnesium slag, steel slag, and construction waste residue were mixed at a mass ratio of 2:2:1 and dried in a 105℃ drying oven for 3 hours. After drying, the mixture was pulverized and passed through a 150-mesh sieve. The sieved solid waste powder was added to deionized water at a solid-liquid ratio of 1:10 and leached by stirring at 250 r / min for 1.5 hours to obtain a calcium-magnesium mixed solution. The calcium content in the solution was then analyzed. 2+ and Mg 2+ The molar ratio is 1:0.5; 2) Heat the above calcium-magnesium mixed solution to 70°C and keep it at that temperature. Add the compound additive (sodium citrate to low molecular weight sodium polyacrylate in a mass ratio of 1:0.8) at a rate of 0.3% of the total mass of the mixed solution. Continue stirring at 250 r / min for 20 min until the additive is completely dissolved. 3) Industrial-grade carbon dioxide (CO2 concentration ≥ 99.99%) was introduced into the insulated additive-mixed solution system through an annular gas distributor, with the gas flow rate controlled at 20 m / s, to conduct a flow-field synergistic mineralization reaction for 4 hours. At this flow rate, the CO2 jet could effectively penetrate the liquid layer and form a stable turbulent field. This significantly enhanced the renewal of the gas-liquid interface and the dissolution and mass transfer process of CO2. Simultaneously, the fluid shearing effect generated by the high-speed gas flow could exert directional mechanical guidance on the crystal nuclei and growing whiskers in the solution, promoting their orderly arrangement and growth along the streamline direction, effectively inhibiting the random aggregation and three-dimensional disordered growth of crystal nuclei, thus facilitating the formation of aragonite whiskers with high aspect ratio and good dispersion.

[0027] 4) After the reaction was completed, solid-liquid separation was performed by vacuum filtration at 0.06 MPa. The solid product was collected and dried in a drying oven at 70℃ for 3 hours to obtain aragonite whiskers.

[0028] Testing revealed that the aragonite whiskers prepared in this embodiment contained 95% aragonite phase, with a whisker diameter of 8-15 μm and an aspect ratio of 35:1. No obvious agglomeration was observed. This embodiment demonstrates that the synergistic effect of turbulent mass transfer and moderate shear at a flow rate of 20 m / s can achieve the preparation of high-purity, highly oriented aragonite whiskers.

[0029] Example 2 This invention provides a method for preparing aragonite whiskers by synergistic mineralization of solid waste using a high-speed CO2 flow field, the specific steps of which are as follows: 1) Magnesium slag and construction waste residue were mixed at a mass ratio of 3:1 and dried in a 110℃ drying oven for 2.5 hours. After drying, the mixture was crushed and passed through a 120-mesh sieve. The sieved solid waste powder was added to deionized water at a solid-liquid ratio of 1:10 and leached by stirring at 220 r / min for 2 hours to obtain a calcium-magnesium mixed solution. The Ca content in the solution was then tested. 2+ and Mg 2+ The molar ratio is 1:0.4; 2) Heat the above calcium-magnesium mixed solution to 65°C and keep it at that temperature. Add the compound additive (EDTA-2Na to polyethylene glycol in a mass ratio of 1:1) at a rate of 0.2% of the total mass of the mixed solution. Continue stirring at 220 r / min for 15 min until the additive is completely dissolved. 3) In the heat-insulated additive-mixed solution system, industrial-grade carbon dioxide (CO2 concentration ≥ 99.99%) is introduced into the system through an annular gas distributor, and the gas flow rate is controlled at 15 m / s to carry out the flow field synergistic mineralization reaction for 5 hours; 4) After the reaction was completed, solid-liquid separation was performed by vacuum filtration at 0.05 MPa. The solid product was collected and dried in a drying oven at 65℃ for 3.5 h to obtain aragonite whiskers.

[0030] Testing revealed that the aragonite whiskers prepared in this embodiment had an aragonite phase content of 92%, a whisker diameter of 10-18 μm, an aspect ratio of 30:1, and good dispersibility. This indicates that by appropriately reducing the flow rate and extending the reaction time, high-performance whiskers can still be obtained, making them suitable for applications with slightly lower aspect ratio requirements.

[0031] Example 3 This invention provides a method for preparing aragonite whiskers by synergistic mineralization of solid waste using a high-speed CO2 flow field, the specific steps of which are as follows: 1) Magnesium slag and steel slag were mixed at a mass ratio of 1:1 and dried in a 120℃ drying oven for 2 hours. After drying, the mixture was crushed and passed through a 200-mesh sieve. The sieved solid waste powder was added to deionized water at a solid-liquid ratio of 1:20 and leached by stirring at 300 r / min for 1 hour to obtain a calcium-magnesium mixed solution. The Ca content in the solution was then tested. 2+ and Mg 2+ The molar ratio is 1:0.6; 2) Heat the above calcium-magnesium mixed solution to 80°C and keep it at that temperature. Add the compound additive (sodium citrate to polyethylene glycol mass ratio 1:0.6) at a rate of 0.4% of the total mass of the mixed solution. Continue stirring at 300 r / min for 25 min until the additive is completely dissolved. 3) After heat preservation, the additive-mixed solution system was continuously fed with flue gas from the tail of a chemical reactor (CO2 concentration 25%, temperature 280-350℃) through an annular gas distributor. The gas flow velocity was controlled at 25 m / s to conduct a flow-field synergistic mineralization reaction for 3 hours. The higher gas flow velocity significantly improved the turbulence intensity and overall kinetic energy of the flow field. This further enhanced the CO2 mass transfer process and the heat and mass transfer of the reaction system. The strong turbulent shear effect not only greatly promoted the micro-mixing of reactants and eliminated the concentration gradient, but also provided stronger hydrodynamic guidance for the highly directional growth of aragonite whiskers, thus facilitating the formation of whisker morphologies with finer diameters and higher aspect ratios. The residual heat of the flue gas helped maintain the reaction activity and promote rapid nucleation. 4) After the reaction was completed, solid-liquid separation was performed by vacuum filtration at 0.07 MPa. The solid product was collected and dried in an 80℃ drying oven for 2 hours to obtain aragonite whiskers.

[0032] Testing revealed that the aragonite whiskers prepared in this embodiment had an aragonite phase content of 96%, a whisker diameter of 5-10 μm, an aspect ratio of 40:1, and excellent crystal purity. This indicates that high flow rate combined with suitable temperature flue gas can significantly enhance the flow field effect, enabling the preparation of ultrafine, ultra-high aspect ratio aragonite whiskers.

[0033] Example 4 This invention provides a method for preparing aragonite whiskers by synergistic mineralization of solid waste using a high-speed CO2 flow field, the specific steps of which are as follows: 1) Steel slag and construction waste residue were mixed at a mass ratio of 2:1 and dried in a 100℃ drying oven for 4 hours. After drying, the mixture was crushed and passed through a 100-mesh sieve. The sieved solid waste powder was added to deionized water at a solid-liquid ratio of 1:30 and leached by stirring at 200 r / min for 1.5 hours to obtain a calcium-magnesium mixed solution. The calcium content in the solution was then tested. 2+ and Mg 2+ The molar ratio is 1:0.3; 2) Heat the above calcium-magnesium mixed solution to 60°C and keep it at that temperature. Add the compound additive (EDTA-2Na to low molecular weight sodium polyacrylate in a mass ratio of 1:0.7) at a rate of 0.1% of the total mass of the mixed solution. Continue stirring at 200 r / min for 15 min until the additive is completely dissolved. 3) In the heat-insulated additive-mixed solution system, lime kiln tail gas (CO2 concentration 28%, temperature 480-510℃) is continuously introduced into the system through an annular gas distributor, and the gas flow rate is controlled at 18m / s to carry out flow field synergistic mineralization reaction for 6 hours. 4) After the reaction was completed, solid-liquid separation was performed by vacuum filtration at 0.08 MPa. The solid product was collected and dried in a drying oven at 60℃ for 4 hours to obtain aragonite whiskers.

[0034] Testing revealed that the aragonite whiskers prepared in this embodiment contained 91% aragonite phase, with whisker diameters of 12-20 μm and aspect ratios of 25:1, which meets the application requirements of conventional functional materials.

[0035] Comparative Examples 1-4 The methods for preparing aragonite whiskers by high-speed CO2 flow field synergistic mineralization in Comparative Examples 1-4 and Examples 1-4 are the same, except that the high-speed CO2 gas blowing operation in step 3 is omitted, and instead, CO2 gas of equal concentration is statically introduced into the solution. There is no flow field shearing and mass transfer enhancement effect, and the mineralization reaction is completed solely by natural diffusion.

[0036] Comparative Examples 5-8 The methods for preparing aragonite whiskers by high-speed CO2 flow field synergistic mineralization in Comparative Examples 5-8 and Examples 1-4 are the same, except that no compound additives are added in step 2. Only an equal amount of deionized water is added to the calcium-magnesium mixed solution. There is no auxiliary effect of crystal form regulation and dispersion stabilization. The high-speed CO2 flow field mineralization reaction is carried out directly.

[0037] The aragonite whiskers prepared in Examples 1-4 all meet the application performance requirements of composite material reinforcing phase and environmentally friendly adsorbent material, with an aragonite phase content of ≥91%, an aspect ratio of ≥25:1, and a dispersion grade of good or above, demonstrating excellent comprehensive performance.

[0038] Examples 1-4 demonstrate that by precisely limiting the types and amounts of solid waste raw materials and scientifically adjusting process parameters such as CO2 flow rate, temperature, and additive ratio, the prepared aragonite whiskers all exhibit excellent characteristics such as high aragonite phase ratio, uniform whisker diameter, and controllable aspect ratio.

[0039] Compared with Example 1, Example 4 showed a decrease in the proportion of aragonite phase. This was mainly because Example 4 did not use industrial-grade carbon dioxide or magnesium slag components, had a lower solution temperature, and used only steel slag and construction waste residue as raw materials, resulting in a lower Mg content in the calcium-magnesium mixed solution. 2+ The low proportion (molar ratio 1:0.3) weakens the induction and stabilization effect on aragonite crystal form, and the insufficient concentration of effective reacting ions also affects the sufficiency of the mineralization and carbon fixation reaction.

[0040] The preparation methods of Comparative Examples 1-4 are basically the same as those of Examples 1-4. The core difference is that Comparative Examples 1-4 omits the "high-speed CO2 gas flow" operation in step 3, and instead statically introduces CO2 gas of the same concentration into the solution. As a result, the aragonite phase ratio (65-72%) and aspect ratio (8-12:1) of Comparative Examples 1-4 are significantly inferior to those of Examples 1-4. The core reason is that the high-speed CO2 flow field in Examples 1-4 can enhance the mass transfer efficiency of CO2 in the solution, and at the same time guide the aragonite whisker directional growth and inhibit agglomeration through the shear force of the flow field; while Comparative Examples 1-4 lack the mass transfer and shearing effect of the high-speed flow field, the CO2 diffusion depth is insufficient, and the whisker growth is not directionally guided. It is impossible to form a uniform aragonite crystal form, and it is difficult to ensure the morphological regularity of the whiskers, ultimately leading to a decline in performance.

[0041] Compared with Examples 1-4, Comparative Examples 5-8 showed a significantly lower aragonite phase content (34-45%) and severe whisker agglomeration. This is because Comparative Examples 5-8 did not contain any compound additives, thus lacking crystal form regulators for Mg. 2+ Regulation of release rate and Mg 2+ The synergistic effect of the additives cannot effectively suppress the formation of heteromorphic crystals such as calcite; at the same time, without the interfacial stabilizing effect of the dispersing additives, the initial crystal nuclei of whiskers are prone to agglomeration, which ultimately leads to a decrease in the proportion of aragonite phase and a significant decrease in carbon fixation efficiency.

[0042] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0043] This invention utilizes a high-speed CO2 gas flow to construct a dynamic turbulent flow field, enhancing the CO2-calcium-magnesium ion mass transfer reaction and the directional growth of aragonite whiskers. This method integrates multiple disciplines, including fluid dynamics-enhanced mass transfer, solid waste resource utilization, low-temperature mineralization, and crystal form control, and is suitable for large-scale applications in the high-value utilization of industrial solid waste and the preparation of low-carbon materials.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing aragonite whiskers by synergistic mineralization of solid waste using a high-speed CO2 flow field, characterized in that, Includes the following steps: 1) Containing Ca 2+ and Mg 2+ The solid waste raw materials are crushed and then prepared into a mixed solution; 2) Control the temperature of the mixed solution at ≥60℃, add the compound additive, and stir until completely dissolved; 3) A high-speed CO2 gas flow is introduced into the solution of step 2), and the high-speed gas flow is used to blow the solution to carry out a mineralization reaction; 4) After the reaction is complete, the solid and liquid are separated and dried to obtain aragonite whiskers.

2. The method according to claim 1, characterized in that, In step 2), the compound admixture includes a crystal form regulator and a dispersant admixture. The mass ratio of the crystal form regulator to the dispersant additive is 1:(0.5-1).

3. The method according to claim 2, characterized in that, The crystal form regulator is selected from at least one of sodium citrate and disodium ethylenediaminetetraacetate; the dispersant additive is selected from at least one of sodium low molecular weight polyacrylate and polyethylene glycol.

4. The method according to claim 1, characterized in that, The total amount of the compound additive is 0.05-0.5% of the total mass of the mixed solution.

5. The method according to claim 1, characterized in that, In step 3), the flow rate of the high-speed CO2 gas is 10-50 m / s, and the mineralization reaction time is 2-6 h.

6. The method according to claim 1, characterized in that, The high-speed CO2 gas flow is introduced into the solution in a turbulent manner through a nozzle or gas distributor.

7. The method according to claim 1, characterized in that, In step 1), the solid waste raw material is selected from at least two of magnesium slag, steel slag, and construction waste residue.

8. The method according to claim 1, characterized in that, Ca in the mixed solution 2+ With Mg 2+ The molar ratio is 1:(0.2-0.8).

9. An aragonite whisker, characterized in that, Obtained by means of any one of claims 1-8.

10. The aragonite whiskers according to claim 9, characterized in that, The aragonite whiskers have an aragonite phase content of ≥90%, a diameter of 5-20μm, and an aspect ratio of 20-50:1.

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