Porous spherical high-activity magnesium oxide and preparation method thereof

Abstract

The application provides a porous spherical high-activity magnesium oxide and a preparation method thereof; the preparation method of the porous spherical high-activity magnesium oxide comprises the following steps: S1, obtaining a magnesium bicarbonate solution; S2, performing spray drying on the magnesium bicarbonate solution to obtain light magnesium carbonate solid powder, wherein the light magnesium carbonate solid powder has a hollow spherical structure; and S3, performing calcination on the light magnesium carbonate solid powder to obtain the porous spherical high-activity magnesium oxide. The high-activity magnesium oxide with a porous hollow spherical structure can be obtained, and the prepared magnesium oxide reaches the product standard of activity-180 in the standard HG / T 3928-2012 Industrial Active Light Magnesium.

Description

Technical Field

[0001] This invention belongs to the field of magnesium oxide preparation, and particularly relates to a porous spherical highly active magnesium oxide and its preparation method. Background Technology

[0002] In recent years, the demand for magnesium oxide has been increasing. my country's annual production of magnesium oxide accounts for more than 75% of the global total. As an important high-performance fine inorganic material, it has been widely used in ceramics, refractory materials, medicine, food, cosmetics, paints, coatings, catalytic materials and other fields. Different products have different requirements for the structure, properties and activity of magnesium oxide itself. At present, most of the magnesium oxide produced in China is a common chemical raw material, and high-activity magnesium oxide is mostly imported.

[0003] Chinese invention patent CN115072752A discloses a method for preparing high-purity magnesium oxide using lightly calcined dolomite. The method involves adding a suitable amount of finely powdered lightly calcined dolomite to hot water at a liquid-to-solid ratio of 40:1 and stirring and digesting in a constant-temperature water bath for 1 hour to obtain a digestion emulsion. The digestion emulsion is filtered multiple times to obtain a refined magnesium filter cake. Water is added to the refined magnesium filter cake, and then both the filter cake and the filtrate are transferred to a carbonization device while CO2 is introduced and the mixture is stirred and carbonized for a certain time. After carbonization, the emulsion is filtered to obtain heavy magnesium water, which is then pyrolyzed at a certain temperature for a period of time to obtain basic magnesium carbonate precipitate. The basic magnesium carbonate is then calcined at a certain temperature to obtain magnesium oxide powder. Although the above patent application successfully prepared magnesium oxide, the use of an electric heating pot for pyrolysis of the heavy magnesium water makes it difficult to obtain porous, hollow, spherical, highly active magnesium oxide.

[0004] In view of this, it is necessary to provide a porous spherical high-activity magnesium oxide and a preparation method thereof, so as to solve or at least alleviate the technical defects of the prior art in not obtaining porous hollow spherical high-activity magnesium oxide. Summary of the Invention

[0005] The main objective of this invention is to provide a porous spherical high-activity magnesium oxide and its preparation method, aiming to solve or at least alleviate the technical problem of the prior art failing to obtain porous hollow spherical high-activity magnesium oxide.

[0006] To achieve the above objectives, the present invention provides a method for preparing porous spherical highly active magnesium oxide, comprising the following steps:

[0007] S1, to obtain magnesium bicarbonate solution;

[0008] S2, spray-dry the magnesium bicarbonate solution to obtain light magnesium carbonate solid powder, the light magnesium carbonate solid powder having a hollow spherical structure;

[0009] The liquid feed rate for spray drying is 20-40 mL / min, the atomization pressure for spray drying is 0.17-0.23 MPa, and the temperature for spray drying is 200-240℃.

[0010] S3, the light magnesium carbonate solid powder is calcined to obtain porous spherical highly active magnesium oxide;

[0011] The calcination temperature is 590-700℃, and the calcination time is 2-4 hours.

[0012] Furthermore, the nozzle used in the spray drying process has an orifice diameter of 0.7-1.3 mm.

[0013] Furthermore, the spray drying is carried out in a spray dryer with a fan frequency of 45-55Hz.

[0014] Furthermore, the process of obtaining the magnesium bicarbonate solution includes the following sub-steps:

[0015] S11 provides calcined white;

[0016] S12, the calcined white material is digested with water to obtain a digested slurry;

[0017] S13, the digested slurry is carbonized to obtain carbonized slurry;

[0018] S14, the carbonized slurry is subjected to solid-liquid separation to obtain the magnesium bicarbonate solution.

[0019] Furthermore, the process of obtaining the calcined white stone includes: calcining dolomite at 800-1200℃ for 1-5 hours to obtain the calcined white stone.

[0020] Furthermore, in sub-step S12, the mass-to-volume ratio of the calcined white powder to water is 1g:15mL to 1g:30mL; the mixing temperature used for digestion is 50 to 90℃.

[0021] Furthermore, the carbonization process includes: introducing carbon dioxide gas into the digested slurry; the endpoint pH of the carbonization is 7.2 to 7.8.

[0022] Furthermore, the carbonization process also includes removing residues from the digested slurry by solid-liquid separation before introducing carbon dioxide gas into the digested slurry.

[0023] Furthermore, the concentration of magnesium bicarbonate in the magnesium bicarbonate solution is 8–10 g / L.

[0024] The present invention also provides a porous spherical highly active magnesium oxide, which is prepared by any of the preparation methods described above.

[0025] The hydrothermal reaction formula for magnesium dihydrogen phosphate is:

[0026] Mg(HCO3)2 + 2H2O → MgCO3·3H2O + CO2 ↑ (Equation 1)

[0027] 5MgCO3·3H2O → 4MgCO3·Mg(OH)2·8H2O + 6H2O Formula 2

[0028] 4MgCO3·Mg(OH)2·8H2O → 4MgCO3·Mg(OH)2·5H2O + 3H2O Formula 3

[0029] 4MgCO3·Mg(OH)2·5H2O → 4MgCO3·Mg(OH)2·4H2O + H2O Formula 4

[0030] Compared with the prior art, the present invention has at least the following advantages:

[0031] This invention can obtain highly active, porous, hollow spherical magnesium oxide, and the prepared magnesium oxide meets the Activity-180 product standard in standard HG / T3928-2012 "Industrial Active Light Magnesium Oxide". Specifically, this invention directly spray-dries heavy magnesium hydrate, and under specific pressure, speed, and temperature conditions, can directly prepare uniform nanoparticle materials (hollow spherical MgCO3·3H2O; the heavy magnesium hydrate is instantaneously heated during spray pyrolysis, so only the decomposition of Formula 1 occurs). The synthesis process is simple and the properties are stable. Subsequently, calcination at a specific temperature can decompose MgCO3·3H2O while maintaining the hollow spherical structure, allowing H2O and CO2 to escape. In this way, the hollow spherical precursor provides a landing point for the escape of H2O and CO2, forming a large number of pores, which greatly increases the specific surface area of ​​magnesium oxide and makes the product highly active. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0033] Figure 1 The images shown are SEM images of the precursor material in Example 1 of this invention; where (a) has a magnification of 2000x and a scale bar of 10μm; and (b) has a magnification of 10000x and a scale bar of 1μm.

[0034] Figure 2The images shown are SEM images of the products prepared in Example 1 of this invention; where (a) has a magnification of 2000x and a scale bar of 10μm; and (b) has a magnification of 50000x and a scale bar of 500nm.

[0035] Figure 3 The distribution diagram of surface pores and pore size of the product prepared in Example 1 of the present invention (N2 adsorption-desorption isotherm and pore size distribution curve);

[0036] Figure 4 The image shown is a SEM image of the precursor material in Comparative Example 1 of this invention, with a magnification of 2000x and a scale bar of 10μm.

[0037] Figure 5 The image shown is an SEM image of the product prepared in Comparative Example 1 of this invention, with a magnification of 2000x and a scale bar of 10μm.

[0038] Figure 6 The distribution diagram of surface pores and pore size of the product prepared in Comparative Example 1 of the present invention (N2 adsorption-desorption isotherm and pore size distribution curve);

[0039] Figure 7 The image shown is a SEM image of the precursor material in Comparative Example 2 of this invention, magnified 1000 times, with a scale bar of 10 μm.

[0040] Figure 8 The image shown is a SEM image of the product prepared in Comparative Example 2 of this invention, with a magnification of 2000x and a scale bar of 10μm.

[0041] Figure 9 The distribution diagram of surface pores and pore size of the product prepared in Comparative Example 2 of the present invention (N2 adsorption-desorption isotherm and pore size distribution curve);

[0042] Figure 10 The image shown is a SEM image of the product prepared in Comparative Example 3 of this invention, with a magnification of 2000x and a scale bar of 10μm.

[0043] Figure 11 The distribution diagram of surface pores and pore size of the product prepared in Comparative Example 3 of the present invention (N2 adsorption-desorption isotherm and pore size distribution curve);

[0044] Figure 12 The image shown is an SEM image of the product prepared in Comparative Example 4 of this invention, with a magnification of 2000x and a scale bar of 10μm.

[0045] Figure 13 The distribution diagram of surface pores and pore size of the product prepared in Comparative Example 4 of this invention (N2 adsorption-desorption isotherm and pore size distribution curve);

[0046] Figure 14The image shown is a SEM image of the precursor material in Comparative Example 5 of this invention, with a magnification of 500x and a scale bar of 50 μm.

[0047] Figure 15 The images shown are SEM images of the products prepared in Comparative Example 5 of this invention; where (a) has a magnification of 2000x and a scale bar of 10μm; and (b) has a magnification of 5000x and a scale bar of 5μm.

[0048] Figure 16 This is a distribution diagram of surface pores and pore size of the product prepared in Comparative Example 5 of the present invention (N2 adsorption-desorption isotherm and pore size distribution curve).

[0049] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0052] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0053] This invention provides a method for preparing porous spherical highly active magnesium oxide, comprising the following steps:

[0054] S1, to obtain a magnesium bicarbonate solution.

[0055] The magnesium bicarbonate solution may include magnesium hydroxide; the concentration of magnesium bicarbonate in the magnesium bicarbonate solution may be 8-10 g / L; no dispersant is mixed into the magnesium bicarbonate solution of the present invention.

[0056] The process of obtaining the magnesium bicarbonate solution includes the following sub-steps:

[0057] S11, providing calcined white; the process of obtaining the calcined white may include: calcining dolomite at 800-1200℃ for 1-5 hours to obtain the calcined white.

[0058] S12, the calcined white powder is digested with water to obtain a digested slurry; the mass-volume ratio of the calcined white powder to water can be 1g:15mL to 1g:30mL; the mixing temperature used for digestion can be 50 to 90℃.

[0059] The digestion process may include: mixing the calcined white powder with water for 1.5-2.5 hours, and then aging (letting stand) for 10-15 hours; wherein the temperature of the mixing process can be 50-90°C, and the aging process can be carried out at room temperature.

[0060] S13, the digested slurry is carbonized to obtain carbonized slurry.

[0061] The carbonization process may include: introducing carbon dioxide gas into the digested slurry; the endpoint pH of the carbonization is 7.2 to 7.8.

[0062] The carbonization process may further include removing insoluble residues from the digested slurry by solid-liquid separation before introducing carbon dioxide gas into the digested slurry.

[0063] In this invention, the carbonization process is specifically as follows: carbon dioxide is introduced into the digested slurry after removing residue using an aeration head to carry out the carbonization reaction, while stirring and reacting, and the pH change of the reaction is monitored in real time. When the pH drops to 7.5, it is the carbonization endpoint, and the aeration is stopped. Afterward, stirring continues until the solution cools to room temperature, and the pH is monitored. After the mass transfer of the solution stabilizes, if the pH rises, carbon dioxide is introduced again until the solution pH≈7.5. If the pH remains unchanged, the next step is performed.

[0064] S14, the carbonized slurry is subjected to solid-liquid separation to obtain the magnesium bicarbonate solution (demagnesium hydroxide) and calcium carbonate solid.

[0065] S2, spray-dry the magnesium bicarbonate solution to obtain light magnesium carbonate solid powder, the light magnesium carbonate solid powder having a hollow spherical structure, the light magnesium carbonate being magnesium carbonate trihydrate MgCO3·3H2O.

[0066] The liquid inlet rate for spray drying is 20-40 mL / min, the atomization pressure for spray drying is 0.17-0.23 MPa, and the temperature for spray drying is 200-240℃.

[0067] The spray drying is mainly for pyrolyzing (atomizing and heating) the magnesium bicarbonate solution to obtain hollow spherical magnesium carbonate trihydrate; the spray drying is carried out in a spray drying device, and the nozzle used in the spray drying has an orifice diameter of 0.7-1.3 mm; the spray drying is implemented in a spray dryer, and the fan frequency can be 45-55 Hz.

[0068] The principle of spray drying is as follows: the solution is pressurized and atomized, and the water in the atomized solution is evaporated by a heater. The particles are collected by a cyclone collector. The advantage of spray drying is that the sprayed material is only heated to high temperature when it is atomized, and the heating is instantaneous. Therefore, the active material retains its active ingredients after drying, and the particle size of the dried product is uniform.

[0069] S3, the light magnesium carbonate solid powder is calcined to obtain porous spherical highly active magnesium oxide; the calcination temperature is 590-700℃, and the calcination time is 2-4 hours. After calcination, the light magnesium carbonate solid powder exhibits only slight agglomeration, the synthesis process is simple, the product has stable properties, and high activity.

[0070] In this invention, the magnesium bicarbonate solution prepared from dolomite through calcination, digestion, and carbonization is a magnesium bicarbonate solution. After spray drying and pyrolysis, it can form a well-dispersed and uniformly fine hollow spherical magnesium carbonate trihydrate powder material. When this material is calcined at 600°C, it decomposes to form hollow spherical magnesium oxide. During the decomposition process, H2O and CO2 escape, breaking through the framework of the precursor and forming highly loosely dispersed magnesium oxide. The calcination process can cause slight agglomeration of the powder material and increase the lattice distortion of the nanoparticles, thereby introducing more active sites and improving the activity of magnesium oxide.

[0071] The magnesium oxide material prepared by this invention is hollow spheres with porous surfaces, high specific surface area, small and uniform particle size distribution, and high activity. It meets the product standard of Activity-180 in standard HG / T3928-2012 "Industrial Active Light Magnesium Oxide" and has a wide range of applications.

[0072] The present invention also provides a method for preparing porous spherical highly active magnesium oxide, which is prepared by any of the preparation methods described above.

[0073] The following are specific examples of the present invention:

[0074] Example 1

[0075] A method for preparing porous spherical highly active magnesium oxide includes the following steps:

[0076] Step 1: Calcine dolomite in a muffle furnace at 1000℃ for 3 hours to obtain calcined dolomite;

[0077] Step 2: Weigh 100g of calcined white powder and dissolve it in 2L of water at 80℃. Stir the mixture in the 80℃ water for 2 hours, then let it stand and age for 12 hours (at room temperature) to obtain the digested slurry.

[0078] Step 3: Filter the digested slurry through a 200-mesh sieve to remove insoluble residues from the digested slurry, obtaining a digested slurry after residue removal (for carbonization reaction);

[0079] Step 4: Use an aeration head to introduce carbon dioxide into the digested slurry obtained in Step 3 to carry out the carbonization reaction. Stir and react simultaneously, and monitor the pH change in real time. When the pH drops from about 12 to 7.5, stop aeration. Then, continue stirring for about 20 minutes until the carbonized slurry cools to room temperature, and monitor the pH. If the pH rises, continue to introduce carbon dioxide until the solution pH≈7.5.

[0080] Step 5: Filter the slurry obtained from the carbonization reaction in step 4 using filter paper to obtain a clear filtrate and a white solid. The filtrate is magnesium hydroxide, and the white solid is mainly calcium carbonate.

[0081] Step 6: Spray dry (pyrolyze) the magnesium bicarbonate solution (magnesium bicarbonate concentration of 8.5 g / L) in an OM-2000A small spray dryer of Shanghai Oumeng Industrial Co., Ltd. to obtain light magnesium carbonate solid powder (precursor material);

[0082] The spray drying temperature was 230℃, the liquid feed rate was 30mL / min, the fan frequency was 50Hz, the atomization pressure was 0.2MPa, and the nozzle diameter was 1mm.

[0083] Step 7: Calcining the light magnesium carbonate obtained in Step 6 to obtain porous spherical highly active magnesium oxide (prepared product); the calcination temperature is 600℃ and the calcination holding time is 3h.

[0084] In this embodiment, the light magnesium carbonate solid powder is magnesium carbonate trihydrate MgCO3·3H2O. Because the heavy magnesium water is heated instantaneously during spray pyrolysis, only the decomposition of formula 1 in the heavy magnesium water pyrolysis reaction occurs; see [link to relevant documentation]. Figure 1 As shown, the light magnesium carbonate solid powder is in the form of hollow spheres.

[0085] In this embodiment, the SEM image of the porous spherical highly active magnesium oxide is as follows: Figure 2 As shown, the product morphology is consistent with the precursor, being a hollow sphere with a smooth surface and pores, uniform particle size, and good dispersibility.

[0086] In this embodiment, see Figure 3 As shown, the porous spherical highly active magnesium oxide has a d50 of 222 nm and a specific surface area of ​​49.43 m². 2 / g, the pore size distribution curve is between 2-160nm, and the average adsorption pore size (4V / A) of BJH is 39.1076nm.

[0087] The activity test showed a CAA value of 16.6s and an iodine uptake value of 220.97 mgI2 / gMgO, meeting the product standard of Activity-180 in the standard HG / T3928-2012 "Industrial Active Light Magnesium Oxide".

[0088] Comparative Example 1

[0089] Compared to Example 1, this comparative example only changed the spray drying temperature to 180°C, while keeping other conditions unchanged.

[0090] In this comparative example, see Figure 4 As shown, the precursor material contains a large amount of agglomerated undecomposed products and a low content of spherical products.

[0091] In this comparative example, see Figure 5 As shown, the prepared product contains not only hollow spheres, but also incompletely decomposed lamellar products;

[0092] In this comparative example, see Figure 6 As shown, the prepared product has a d50 of 386.43 nm and a specific surface area of ​​only 3.90 m². 2 / g, this is due to incomplete decomposition of magnesium hydroxide by heat, the pore size distribution curve is between 2-200nm, and the average adsorption pore size (4V / A) of BJH is 38.66nm.

[0093] The activity test showed a CAA value of 52.65s and an iodine uptake value of 146.68 mgI2 / g MgO, meeting the product standard of Activity-120 in the standard HG / T3928-2012 "Industrial Active Light Magnesium Oxide".

[0094] Comparative Example 2

[0095] Compared to Example 1, this comparative example only changed the spray drying temperature to 250°C, while keeping other conditions unchanged.

[0096] In this comparative example, see Figure 7 As shown, when the spray pyrolysis temperature is too high, the precursor material has a hollow spherical shape, as well as a sheet-like structure after the spherical disintegration, and the precursor agglomeration phenomenon is obvious.

[0097] In this comparative example, see Figure 8 As shown, the morphology of the prepared product is basically the same as that of the precursor, and the aggregation phenomenon is serious.

[0098] In this comparative example, see Figure 9As shown, the prepared product has a d50 of 291.46 nm and a specific surface area of ​​35.44 m². 2 / g, the pore size distribution curve is between 2-160nm, and the average adsorption pore size (4V / A) of BJH is 38.82nm.

[0099] The activity test showed a CAA value of 47.71s and an iodine uptake value of 162.94 mgI2 / g MgO, meeting the product standard of Activity-150 in the standard HG / T3928-2012 "Industrial Active Light Magnesium Oxide".

[0100] Comparative Example 3

[0101] Compared to Example 1, this comparative example only changed the calcination temperature in step 7 to 500°C, while keeping other conditions unchanged.

[0102] In this comparative example, see Figure 10 As shown, calcination at too low a temperature will not destroy the hollow spherical structure; however, according to subsequent analysis, it will reduce the activity of magnesium oxide.

[0103] In this comparative example, see Figure 11 As shown, the prepared product has a d50 of 211.81 nm and a specific surface area of ​​49.35 m². 2 / g, the pore size distribution curve is between 2-160nm, the average adsorption pore size (4V / A) of BJH is 35.32nm, and the porosity decreases.

[0104] The activity test showed a CAA value of 43.07s and an iodine uptake value of 177.66mgI2 / g MgO, meeting the product standard of Activity-150 in the standard HG / T3928-2012 "Industrial Active Light Magnesium Oxide".

[0105] Comparative Example 4

[0106] Compared to Example 1, this comparative example only changed the calcination temperature in step 7 to 800°C, while keeping other conditions unchanged.

[0107] In this comparative example, see Figure 12 As shown, the hollow spherical morphology of the prepared product was destroyed and disintegrated, and the aggregation phenomenon was obvious.

[0108] In this comparative example, see Figure 13 As shown, the prepared product has a d50 of 282.95 nm and a specific surface area of ​​25.38 m². 2 / g, the pore size distribution curve is between 2-165nm, the average adsorption pore size (4V / A) of BJH is 16.46nm, and the porosity decreases.

[0109] The activity test showed a CAA value of 133s and an iodine uptake value of 61.04 mgI2 / g MgO, meeting the product standard of Activity-60 in the standard HG / T3928-2012 "Industrial Active Light Magnesium Oxide".

[0110] Comparative Example 5

[0111] Step 1: Obtain magnesium hydroxide solution (same as in Example 1);

[0112] Step 2: The magnesium hydroxide solution is concentrated by evaporation and then pyrolyzed. The magnesium hydroxide solution is heated in an 80°C water bath and stirred until no more bubbles are produced. After filtration, magnesium carbonate 4MgCO3·Mg(OH)2·4H2O (precursor material) is obtained. It contains a small amount of MgCO3·3H2O. The magnesium hydroxide solution pyrolysis reaction of formulas 1 and 4 has occurred. Some of the MgCO3·3H2O has not been completely pyrolyzed and therefore remains in the precursor.

[0113] Step 3: Calcine the above magnesium carbonate at 600℃ for 3 hours to obtain magnesium oxide (prepared product).

[0114] In this comparative example, see Figure 14 As shown, the precursor material is a petal-shaped aggregate with a surface composed of stacked lamellar layers;

[0115] In this comparative example, see Figure 15 As shown, the prepared products are in the form of thin sheets, which are mostly stacked together;

[0116] In this comparative example, see Figure 16 As shown, the prepared product has a d50 of 2620 nm and a specific surface area of ​​61.09 m². 2 / g, the pore size distribution curve is between 2-160nm, and the average adsorption pore size (4V / A) of BJH is 24.01nm.

[0117] The activity test showed a CAA value of 62.15s and an iodine uptake value of 139.59 mgI2 / g MgO, which met the product standard of Activity-120 in the standard HG / T3928-2012 "Industrial Active Light Magnesium Oxide". Although it has a large specific surface area, its activity is worse than that of the product in Example 1 due to the influence of particle size and morphology.

[0118] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for producing a porous spherical high-activity magnesium oxide, characterized by, The method comprises the steps of: S1, obtaining a magnesium bicarbonate solution; S2, spray drying the magnesium bicarbonate solution to obtain light magnesium carbonate solid powder, wherein the light magnesium carbonate solid powder has a hollow spherical structure; The inlet liquid speed of the spray drying is 20-40 mL / min, the atomization pressure used in the spray drying is 0.17-0.23 MPa, and the temperature used in the spray drying is 200-240℃; S3, calcining the light magnesium carbonate solid powder to obtain porous spherical high-activity magnesium oxide; The calcination temperature is 590-700℃, and the calcination time is 2-4 h.

2. The method for preparing porous spherical highly active magnesium oxide according to claim 1, characterized in that, The nozzle used in the spray drying has a pore size of 0.7-1.3 mm.

3. The method for preparing porous spherical highly active magnesium oxide according to claim 1, characterized in that, The spray drying is carried out in a spray dryer, and the frequency of the fan is 45-55 Hz.

4. The method for preparing porous spherical highly active magnesium oxide according to claim 1, characterized in that, The process of obtaining the magnesium bicarbonate solution comprises the following sub-steps: S11, providing calcined white; S12, digesting the calcined white with water to obtain a digestion slurry; S13, carbonizing the digestion slurry to obtain a carbonization slurry; S14, performing solid-liquid separation on the carbonization slurry to obtain the magnesium bicarbonate solution.

5. The method for preparing porous spherical highly active magnesium oxide according to claim 4, characterized in that, The process of obtaining the calcined white comprises calcining dolomite at 800-1200℃ for 1-5 h to obtain the calcined white.

6. The method for preparing porous spherical highly active magnesium oxide according to claim 4, characterized in that, In the sub-step S12, the mass-to-volume ratio of the calcined white to water is 1 g: 15 mL-1 g: 30 mL; and the mixing temperature used in the digestion is 50-90℃.

7. The method for preparing porous spherical highly active magnesium oxide according to claim 4, characterized in that, The process of carbonization comprises introducing carbon dioxide gas into the digestion slurry; and the end-point pH of the carbonization is 7.2-7.

8.

8. The method for preparing porous spherical highly active magnesium oxide according to claim 7, characterized in that, The process of carbonization further comprises removing residues in the digestion slurry by solid-liquid separation before introducing carbon dioxide gas into the digestion slurry.

9. The method of producing porous spherical high-activity magnesium oxide according to any one of claims 1 to 8, characterized by, The concentration of magnesium bicarbonate in the magnesium bicarbonate solution is 8-10 g / L.

10. A porous spherical high activity magnesium oxide, characterized by, The method is prepared by using the preparation method according to any one of claims 1-9.

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