Preparation method of calcite with different calcium-magnesium ratios

Abstract

The invention discloses a preparation method of calcite with different calcium-magnesium ratios, which comprises the following steps of: storing dextran sodium sulfate in a refrigerator, and taking out the dextran sodium sulfate when in use; the method comprises the following steps: adding sodium polyacrylate and dextran sodium sulfate into a centrifuge tube, adding a MgCl2 solution and a CaCl2 solution, mixing, adding a Na2CO3 solution, immediately carrying out a precipitation reaction, completely precipitating all calcium and magnesium ions, and adding reagents in different proportions; after full reaction, immediately carrying out solid-liquid separation by using a centrifugal machine; after reaction liquid is separated, filtering by using a vacuum pump, washing filter residues with deionized water and alcohol for 2-3 times, and drying at room temperature; mixing the prepared calcite powder with deionized water according to the ratio of 0.2 g / 1L, introducing CO2 gas for 6-8 days to ensure that the calcite powder is balanced, and then taking supernate, namely a calcite saturated solution. The invention aims to flexibly prepare calcite solutions with different calcium-magnesium ratios so as to meet diversified application requirements and show extremely high utilization potential and value.

Description

Technical Field

[0001] The invention belongs to the technical field of biomineralization, and in particular relates to a preparation method of calcite with different calcium-magnesium ratios, involving multiple aspects such as chemical synthesis, crystal growth and performance regulation. Background Art

[0002] With the acceleration of the global industrialization process, the demand for high-performance and environmentally friendly materials is growing. As a new type of material, high-magnesium calcite has shown broad application prospects in many fields such as building materials, water treatment, and environmental remediation due to its unique physical and chemical properties. At the same time, the limited global magnesium ore resources and the rising mining costs have prompted people to find more efficient and economical ways to utilize magnesium resources. This patent achieves the preparation of high-magnesium calcite by adjusting the calcium-magnesium ratio, providing a new way for the effective utilization of magnesium resources.

[0003] At present, my country is in a critical period of economic transformation and upgrading, and technological innovation is an important driving force for industrial upgrading. This patent provides a simple, mild, green and pollution-free method for preparing high-magnesium calcite, which not only increases the magnesium content and specific surface area of ​​the product, but also reduces production costs, providing technical support for the upgrading and transformation of related industries.

[0004] With the continuous strengthening of environmental protection policies, traditional high-energy consumption and high-pollution production methods have been unable to meet the requirements of sustainable development. The high-magnesium calcite prepared by this patent has the characteristics of green and pollution-free in the production process, which meets the requirements of environmental protection policies. At the same time, its application as an environmentally friendly material helps to reduce environmental pollution and achieve sustainable development.

[0005] The calcite industry is a highly competitive industry, and the diversification of market demand has prompted companies to continuously innovate to meet market demand. The proposal of this patent provides companies with differentiated competitive advantages in the fierce market competition, helping them to expand their market share and improve economic benefits.

[0006] To sum up, the realistic background of this patent is based on considerations of multiple factors such as market demand, resource utilization, technological innovation, environmental protection policies and industry competition. It aims to promote the upgrading and transformation of related industries and achieve sustainable development by providing an efficient and environmentally friendly high-magnesium calcite preparation method.

[0007] However, the performance of calcite is not static, and its calcium-magnesium ratio becomes the key to regulating its characteristics. At a low calcium-magnesium ratio, calcite crystallization is stable, mainly forming typical calcite crystals; and as the magnesium-calcium ratio increases, magnesium ions can significantly inhibit calcite crystallization, induce aragonite formation, and thus affect its physical and chemical properties. Calcite with a high calcium-magnesium ratio exhibits enhanced adsorption capacity, which is particularly effective for water purification and can efficiently remove heavy metals and impurities. At the same time, in soil improvement, its superior neutralization and adsorption properties help optimize soil chemical properties and improve soil stability and water retention. As for the field of building materials, high calcium-magnesium ratio calcite has become an ideal choice for manufacturing load-bearing materials because of its higher strength and stability. Despite the significant differences, the specific properties of calcite are also affected by factors such as purity, crystal structure and particle size. Summary of the invention

[0008] The purpose of the present invention is to provide a method for preparing calcite with different calcium-magnesium ratios, so as to flexibly configure calcite solutions with different calcium-magnesium ratios to meet diversified application requirements and show extremely high utilization potential and value.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] The present invention discloses a method for preparing calcite with different calcium-magnesium ratios, comprising the following steps:

[0011] Step 1. Store dextran sulfate sodium in the refrigerator until it is needed;

[0012] Step 2. First add sodium polyacrylate (MW: 5100) and sodium dextran sulfate into the centrifuge tube, then add MgCl2 solution and CaCl2 solution and mix them, then add Na2CO3 solution to immediately carry out precipitation reaction, and all calcium and magnesium ions are precipitated. The addition ratio is as follows:

[0013] (1) Ca / Mg = 9:1, requiring 6 mL of Na2CO3 solution, 8.1 mL of CaCl2 solution, and 0.9 mL of MgCl2 solution;

[0014] (2) Ca / Mg = 8:2, requiring 6 mL of Na2CO3 solution, 7.2 mL of CaCl2 solution, and 1.8 mL of MgCl2 solution;

[0015] (3) Ca / Mg = 7:3, requiring 6 mL of Na2CO3 solution, 6.3 mL of CaCl2 solution, and 2.7 mL of MgCl2 solution;

[0016] (4) Ca / Mg=6:4, requiring 6 mL of Na2CO3 solution, 5.4 mL of CaCl2 solution, and 3.6 mL of MgCl2 solution;

[0017] Step 3. After sufficient reaction, use a centrifuge to separate the solid and liquid immediately;

[0018] Step 4. After the reaction liquid is separated, filter it with a vacuum pump, rinse the filter residue with deionized water and alcohol 2-3 times, and dry it at room temperature;

[0019] Step 5. Mix the prepared calcite powder with deionized water at a rate of 0.2 g / 1 L, and pass CO2 gas for 6-8 days to ensure that it reaches equilibrium, and then take the supernatant as the saturated calcite solution; before starting, first measure the pH of the saturated calcite solution, and after aeration, the pH of the solution should be stabilized at 79-8.1, and then use a filter membrane to filter out excess suspended matter; thereby producing saturated calcite solutions with calcium-magnesium ratios of 9:1, 8:2, 7:3, and 6:4, respectively.

[0020] Furthermore, dextran sulfate sodium was stored in a refrigerator at 4°C.

[0021] Furthermore, the mass ratio of sodium polyacrylate to sodium dextran sulfate is 6:30.

[0022] Furthermore, the concentrations of the MgCl2 solution and the CaCl2 solution are both 0.5 mol / L.

[0023] Furthermore, the centrifuge separation conditions were: 2000 r, 20 min.

[0024] Furthermore, 0.22 μm filter membrane was used for filtration.

[0025] Furthermore, the pH of the solution should be stabilized at 8.0 after aeration.

[0026] By flexibly configuring calcite solutions with different calcium-magnesium ratios, compared with the obvious advantages of traditional methods, the following significant technical effects can be obtained through analysis:

[0027] 1. Better crystal morphology and structure control:

[0028] As a polymer template, sodium polyacrylate can effectively control the nucleation and growth process of calcium carbonate (and magnesium-containing calcite), so that the generated crystals have a more regular and uniform morphology, thereby improving the quality and consistency of the product.

[0029] 2. Improve the purity and yield of magnesium-containing calcite:

[0030] The addition of sodium dextran sulfate may enhance the ion exchange and adsorption in the solution, help to more effectively introduce magnesium ions into the lattice of calcium carbonate, and improve the purity of magnesium-containing calcite. At the same time, the presence of the polymer template may also increase the yield of the reaction.

[0031] 3. Wider applicability:

[0032] This method can flexibly control the ratio of magnesium to calcium in the product by adjusting the ratio of MgCl2, CaCl2 and Na2CO3, thereby preparing calcite materials with different magnesium contents to meet the needs of different application fields.

[0033] 4. Energy saving and emission reduction:

[0034] Compared with some traditional methods, this method may have advantages in reaction conditions, energy consumption and wastewater treatment, which will help achieve green synthesis and sustainable development.

[0035] 5. Technical Effects

[0036] Improved product performance: The prepared magnesium-containing calcite material is superior to traditional methods in terms of crystal morphology, purity and structure, and is suitable for application scenarios with higher requirements.

[0037] Improve production efficiency: By optimizing reaction conditions and process flow, production efficiency is improved and production costs are reduced.

[0038] Expanding the scope of application: Due to the improvement of product performance and the increase of flexibility, the magnesium-containing calcite material prepared by this method has broader application prospects in the fields of medicine, materials science, environmental protection, etc.

[0039] In summary, this technical solution shows obvious advantages and technical effects in the synthesis of magnesium-containing calcite, and provides new ideas and methods for research and application in related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is the particle size distribution diagram of calcite with different magnesium contents;

[0041] Figure 2 This is magnesium calcite under an electron microscope (a: pure calcium calcite; b: calcite with a Ca-Mg ratio of 9:1; c: calcite with a Ca-Mg ratio of 8:2; d: calcite with a Ca-Mg ratio of 7:3; e: calcite with a Ca-Mg ratio of 6:4). DETAILED DESCRIPTION

[0042] A method for preparing calcite with different calcium-magnesium ratios comprises the following steps:

[0043] (1) Store dextran sulfate sodium in a refrigerator at 4°C until needed.

[0044] (2) Add 6 mg of sodium polyacrylate (MW: 5100) and 30 mg of sodium dextran sulfate into a centrifuge tube, then add MgCl2 solution (0.5 mol / L) and CaCl2 solution (0.5 mol / L) and mix them, then add Na2CO3 solution to immediately perform precipitation reaction (assuming that all calcium and magnesium ions are precipitated). The addition ratio is as follows:

[0045] 1) Ca / Mg=9:1 requires 6 mL of Na2CO3 solution, 8.1 mL of CaCl2 solution, and 0.9 mL of MgCl2 solution;

[0046] 2) Ca / Mg=8:2 requires 6 mL of Na2CO3 solution, 7.2 mL of CaCl2 solution, and 1.8 mL of MgCl2 solution;

[0047] 3) Ca / Mg=7:3 requires 6 mL of Na2CO3 solution, 6.3 mL of CaCl2 solution, and 2.7 mL of MgCl2 solution;

[0048] 4) Ca / Mg=6:4 requires 6 mL of Na2CO3 solution, 5.4 mL of CaCl2 solution, and 3.6 mL of MgCl2 solution;

[0049] (3) After sufficient reaction, when preparing magnesium-containing calcite powder, use a centrifuge to accelerate solid-liquid separation, set the speed to 2000r / min, and the time to 20min;

[0050] (4) After the reaction liquid is separated, filter it with a vacuum pump (0.22 μm filter membrane), rinse the filter residue with deionized water and alcohol 2-3 times, and dry it at room temperature;

[0051] (5) The concentration of the saturated calcite solution is about 0.2g / L. In order to simulate natural conditions and ensure the complete dissolution of calcite and the balance of CO2 in the liquid, the prepared calcite powder (0.2g) must be mixed with deionized water (1L) and passed through CO2 gas for 6-8 days to ensure that it reaches equilibrium. Then the supernatant is the saturated calcite solution. After aeration, the pH of the solution should be stable at around 8.0. Then, the excess suspended matter is filtered out with a 0.22μm filter membrane to produce saturated calcite solutions with calcium-magnesium ratios of 9:1, 8:2, 7:3, and 6:4, respectively.

[0052] Analysis of the physicochemical characteristics of magnesium calcite in different proportions configured by this method:

[0053] 1. Particle Characterization Analysis

[0054] The particle characteristic analysis of magnesium-containing calcite is mainly a process of measuring the particle size of magnesium calcite, analyzing its changes and thus deriving objective laws. Figure 1Table 1 and Table 2 show the particle size distribution and parameters of calcite with different magnesium contents. According to the normal distribution law, the higher the peak value, the more concentrated the distribution, and the more uniform the synthesized magnesium calcite. S / V in the table represents the volume specific surface area, that is, the surface area of ​​particles per unit volume. A = B means that particles with a particle size smaller than B account for A% of the total number of particles. AV Indicates the average particle size, also known as the median diameter.

[0055] from Figure 1 As can be seen from Table 1, the magnesium calcite configured by this method conforms to the normal distribution law as a whole, and the particle size is relatively uniform. Among them, the calcite with a Ca-Mg ratio of 6:4 has the widest particle size range and the lowest peak. The calcite with a Ca-Mg ratio of 7:3 has the smallest unit surface area, a larger particle size, and a large difference between Dav and D50, while the calcite with other Ca-Mg ratios Dav≈D50. The particle diameter of Ca9Mg1 calcite is the most uniform and is also the largest among the five types of magnesium calcite. It conforms to the particle characteristics of calcite with different calcium-magnesium ratios.

[0056] Table 1 Calcite particle size parameters with different magnesium contents

[0057]

[0058] 2 Surface morphology analysis

[0059] The external morphology of a substance can show its microscopic properties such as its morphology. This method uses an electron microscope to collect calcite surface morphology images, clearly and intuitively observe the structural characteristics of calcite under the electron microscope before adsorption, and the collected images are Figure 2 shown.

[0060] from Figure 2 It can be observed that both pure calcite and magnesium calcite are granular, with good dispersion and no adhesion between particles. The higher the magnesium content in calcite, the closer its shape will be to a sphere. As the magnesium content increases, the lamellar structure of pure calcium calcite disappears.

[0061] In summary, the calcite particles with various magnesium content ratios prepared by this method show highly consistent particle characteristics, uniform particle size distribution, and smooth surface morphology with sharp edges, which are fully consistent with the established quality standards, reflecting the excellent performance of this method in preparing high-quality magnesium-containing calcite.

[0062] The obvious advantages of using this method to prepare magnesium-containing calcite in different proportions compared to the traditional method are mainly reflected in the following aspects:

[0063] 1. Higher stability: By first adding a mixed solution of MgCl2 solution and CaCl2 solution, the ratio of magnesium ions to calcium ions can be better controlled, so that sodium polyacrylate (PAAS) and dextran sulfate (DSS) can be fully combined with these two ions. This can increase the stability of the formed calcite structure because a high proportion of magnesium helps to generate a denser crystal structure.

[0064] 2. Enhanced dispersibility: Since sodium polyacrylate (PAAS) has excellent dispersibility, it can form a network structure in the solution, increase the interfacial activity between the solid phase and the liquid phase, and improve the dispersion effect of mineral particles. Through the preparation of this method, the formed magnesium-containing calcite has better dispersibility, making it easier to achieve uniform distribution in the application.

[0065] 3. Higher chemical durability: Sodium polyacrylate (PAAS) and sodium dextran sulfate (DSS) may produce a chemical reinforcement effect in the mixed system, which can increase the acid and alkali corrosion resistance of magnesium-containing calcite. This allows the magnesium-containing calcite prepared by this method to maintain the stability of its structure and performance in harsh chemical environments.

[0066] 4. Optimize cost-effectiveness: Although this method may slightly increase the initial material, by improving the stability and durability of the product, it may actually extend the service life of the product and reduce the frequency of replacement, thereby optimizing cost-effectiveness in long-term use.

[0067] 5. Better environmental friendliness: Since the additives used in this method (such as PAAS and DSS) usually have good biocompatibility and degradability, the magnesium-containing calcite prepared by this method is more in line with the current environmentally friendly development trend.

[0068] Overall, compared with traditional methods, this method can more effectively improve the comprehensive performance of magnesium-containing calcite, including structural stability, dispersibility, durability and cost-effectiveness. In specific application scenarios, this advantage may be more significant.

[0069] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing calcite with different calcium-magnesium ratios, characterized in that: The steps include: Step 1. Store the dextran sulfate sodium in the refrigerator until it is needed; Step 2. First add sodium polyacrylate and sodium dextran sulfate into the centrifuge tube, then add MgCl2 solution and CaCl2 solution and mix them, then add Na2CO3 solution to immediately carry out precipitation reaction, and all calcium and magnesium ions are precipitated. The addition ratio is as follows: (1) Ca / Mg = 9:1, requiring 6 mL of Na2CO3 solution, 8.1 mL of CaCl2 solution, and 0.9 mL of MgCl2 solution; (2) Ca / Mg = 8:2, requiring 6 mL of Na2CO3 solution, 7.2 mL of CaCl2 solution, and 1.8 mL of MgCl2 solution; (3) Ca / Mg = 7:3, requiring 6 mL of Na2CO3 solution, 6.3 mL of CaCl2 solution, and 2.7 mL of MgCl2 solution; (4) Ca / Mg=6:4, requiring 6 mL of Na2CO3 solution, 5.4 mL of CaCl2 solution, and 3.6 mL of MgCl2 solution; Step 3. After sufficient reaction, use a centrifuge to separate the solid and liquid immediately; Step 4. After the reaction liquid is separated, filter it with a vacuum pump, rinse the filter residue with deionized water and alcohol 2-3 times, and dry it at room temperature; Step 5. Mix the prepared calcite powder with deionized water at a rate of 0.2 g / 1 L, and pass CO2 gas for 6-8 days to ensure that it reaches equilibrium, and then take the supernatant as the saturated calcite solution; before starting, first measure the pH of the saturated calcite solution, and after aeration, the pH of the solution should be stabilized at 79-8.1, and then use a filter membrane to filter out excess suspended matter; thereby producing saturated calcite solutions with calcium-magnesium ratios of 9:1, 8:2, 7:3, and 6:4, respectively.

2. The method for preparing calcite with different calcium-magnesium ratios according to claim 1, characterized in that: Store dextran sulfate sodium in a refrigerator at 4°C.

3. The method for preparing calcite with different calcium-magnesium ratios according to claim 1, characterized in that: The mass ratio of sodium polyacrylate to sodium dextran sulfate is 6:

30.

4. The method for preparing calcite with different calcium-magnesium ratios according to claim 1, characterized in that: The concentrations of MgCl2 solution and CaCl2 solution are both 0.5 mol / L.

5. The method for preparing calcite with different calcium-magnesium ratios according to claim 1, characterized in that: Centrifuge separation conditions: 2000r, 20min.

6. The method for preparing calcite with different calcium-magnesium ratios according to claim 1, characterized in that: The filtration was performed using a 0.22 μm filter membrane.

7. The method for preparing calcite with different calcium-magnesium ratios according to claim 1, characterized in that: After aeration, the pH of the solution should stabilize at 8.0.

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