Method for preparing magnesium oxide from magnesium sulfate

Abstract

The invention relates to the technical field of chemical material synthesis, in particular to a method for preparing magnesium oxide from magnesium sulfate, which comprises the following specific steps: 1) mixing solutions; 2) adding carbon powder; 3) hydrothermal reaction; 4) product separation; 5) calcining; 6) cooling; and 7) crushing and screening: crushing and screening the cooled magnesium oxide to obtain magnesium oxide powder. According to the invention, the reaction can be carried out at a low temperature through the hydrothermal synthesis method, the crystallinity and particle size distribution of the product can be controlled, the preparation of magnesium oxide can be realized under mild conditions, and the prepared magnesium oxide has high activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical material synthesis, and particularly relates to a method for preparing magnesium oxide from magnesium sulfate. Background Art

[0002] Magnesium oxide (MgO) is an important chemical raw material, which has characteristics such as high melting point, high hardness, good chemical stability and electrical insulation, and is widely used in fields such as ceramics, glass, electronic materials, catalysts and adsorbents. Traditional methods for preparing magnesium oxide usually involve high-temperature calcination of magnesium carbonate or magnesium hydroxide, and these methods have problems such as high energy consumption, harsh reaction conditions and relatively low product purity. Therefore, it is of great significance to develop a new method that is efficient, energy-saving and can prepare high-purity magnesium oxide. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing magnesium oxide from magnesium sulfate. This method can prepare high-purity magnesium oxide under mild conditions through hydrothermal synthesis technology, and at the same time has advantages such as low energy consumption, simple operation and controllable product morphology.

[0004] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0005] A method for preparing magnesium oxide from magnesium sulfate, the specific steps include:

[0006] 1) Mixed solution: Dissolve magnesium sulfate powder and sodium bicarbonate in deionized water and stir evenly;

[0007] 2) Add carbon powder: Add graphite powder to the solution and disperse the graphite powder evenly;

[0008] 3) Hydrothermal reaction: Transfer the mixed solution to a hydrothermal reaction kettle; the reaction temperature of the reaction kettle: 160 - 230 °C, the reaction time is 10 - 20 hours, and the pressure in the reaction kettle is 2 - 8 MPa;

[0009] 4) Product separation: After the reaction is completed, cool to room temperature; filter the reaction product, collect the generated magnesium hydroxide precipitate; wash the precipitate to remove residual sodium sulfate and other impurities;

[0010] 5) Calcination: Calcinate the washed magnesium hydroxide precipitate, the calcination temperature: 350 - 600 °C; after heating to the set temperature, keep it calcined at a constant temperature, and the calcination time is 2 - 4 hours; generate magnesium oxide, and water vapor will be released during the calcination process;

[0011] 6) Cooling: After the calcination is completed, take out the calcined magnesium oxide and cool it to room temperature;

[0012] 7) Crushing and screening: Crush and screen the cooled magnesium oxide to obtain magnesium oxide powder.

[0013] The described magnesium sulfate and sodium bicarbonate are in a mass ratio of 1:(1 - 2), the particle size of magnesium sulfate is 1 - 4 mm, and the particle size of sodium bicarbonate is 150 - 200 μm.

[0014] The addition amount of the described carbon powder is 10% - 20% of the mass of magnesium sulfate, and it is stirred evenly to ensure that the carbon powder is evenly dispersed.

[0015] The described calcination is carried out using a muffle furnace or a tube furnace.

[0016] Compared with the existing technology, the beneficial effects of the present invention are as follows:

[0017] The present invention can carry out the reaction at a relatively low temperature through the hydrothermal synthesis method, which is beneficial to controlling the crystallinity and particle size distribution of the product, can realize the preparation of magnesium oxide under mild conditions, and the prepared magnesium oxide has high activity.

[0018] Mild conditions: The hydrothermal method can be carried out under relatively mild conditions, which is suitable for preparing nano-scale or micro-scale magnesium oxide, and has a high specific surface area and good dispersibility.

[0019] High purity: High-purity magnesium oxide can be prepared through the washing and calcination steps.

[0020] Simple operation: The whole process is simple to operate and easy to control.

[0021] Low cost: The raw materials used are inexpensive, and the reaction conditions are mild, without the need for complex equipment and high-temperature and high-pressure conditions, reducing the production cost.

[0022] Environmentally friendly: There is no emission of harmful gases and waste water during the whole preparation process, which is environmentally friendly. Specific embodiments

[0023] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0024] Unless otherwise clearly defined and limited, the terms "installation", "connection", and "linkage" shall 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 a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. Additionally, it should be noted that, among the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not describe various possible combination methods separately. Furthermore, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

[0026] A method for preparing magnesium oxide from magnesium sulfate, the specific steps include:

[0027] 1) Mixing the solution: Dissolve magnesium sulfate powder and sodium bicarbonate in deionized water and stir evenly.

[0028] 2) Adding carbon powder: Add graphite powder to the solution and disperse the graphite powder evenly.

[0029] 3) Hydrothermal reaction: Transfer the mixed solution to a hydrothermal reaction kettle; the reaction temperature of the reaction kettle: 160 - 230 °C, the reaction time is 10 - 20 hours, the pressure inside the reaction kettle is 2 - 8 MPa and increases with the increase of temperature; magnesium sulfate reacts with sodium bicarbonate to generate magnesium hydroxide Mg(OH)2 precipitate and release carbon dioxide CO2 gas at the same time. The reaction equation is as follows: MgSO4 + 2NaHCO3 → Mg(OH)2↓ + Na2SO4 + 2CO2↑

[0030] Graphite powder plays the role of a reducing agent in the hydrothermal reaction, which helps to prevent the oxidation of magnesium ions during the reaction, and at the same time can also adjust the pH value of the reaction system to promote the formation of magnesium hydroxide. Carbon powder reacts with water at high temperature to generate carbon monoxide (CO) and hydrogen (H2), and these gases can further adjust the reaction environment.

[0031] 4) Product separation:

[0032] Cooling: After the reaction is completed, cool to room temperature.

[0033] Filtration: Filter the reaction product and collect the generated magnesium hydroxide precipitate;

[0034] Washing: Remove the residual sodium sulfate and other impurities;

[0035] 5) Calcination: Calcinate the washed magnesium hydroxide precipitate at a calcination temperature of 350 - 600 °C; after heating to the set temperature, maintain a constant temperature for calcination for 2 - 4 hours; magnesium oxide is generated, and water vapor is released during the calcination process;

[0036] 6) Cooling: After the calcination is completed, cool the product to room temperature;

[0037] 7) Crushing and sieving: Crush and sieve the cooled magnesium oxide to obtain magnesium oxide powder with uniform particle size.

[0038] The mass ratio of the magnesium sulfate to the sodium bicarbonate is 1:(1 - 2), the particle size of the magnesium sulfate is 1 - 4 mm, and the particle size of the sodium bicarbonate is 150 - 200 μm.

[0039] The addition amount of the carbon powder is 10% - 20% of the mass of the magnesium sulfate. Stir evenly to ensure uniform dispersion of the carbon powder.

[0040] The calcination is carried out using a muffle furnace or a tube furnace.

[0041] To make the purpose, technical solutions and technical effects of the present invention clearer, the technical solutions in the embodiments of the present invention will now be described clearly and completely. However, the embodiments described below are only a part of the embodiments of the present invention, rather than all the embodiments. Combining the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0042] Example 1:

[0043] The method for preparing magnesium oxide from magnesium sulfate specifically includes the following steps:

[0044] 1) Mixed solution: Weigh 100 g of magnesium sulfate (MgSO4) and 200 g of sodium bicarbonate (NaHCO3), dissolve them in 1 L of deionized water, and stir evenly. The particle size of the magnesium sulfate is 1 - 2 mm, and the particle size of the sodium bicarbonate is 150 - 180 μm.

[0045] 2) Adding carbon powder: Add 10 g of graphite powder and stir evenly.

[0046] 3) Hydrothermal reaction: Transfer the mixed solution to a hydrothermal reaction kettle, set the reaction temperature to 180 °C, the reaction time to 16 hours, and the pressure in the reaction kettle naturally increases to 3 MPa.

[0047] 4) Product separation: After the reaction is completed, cool to room temperature, filter to collect the magnesium hydroxide precipitate, wash it with dilute hydrochloric acid to remove residual impurities, and finally wash it with deionized water until neutral.

[0048] 5) Calcination: Put the washed magnesium hydroxide precipitate into a muffle furnace, set the calcination temperature to 450 °C, and the calcination time to 3 hours.

[0049] 6) Cooling: After the calcination is completed, cool to room temperature.

[0050] 7) Crushing and screening: Crush the cooled magnesium oxide and screen it to a particle size less than 100 mesh.

[0051] Example 2:

[0052] 1) Mixed solution: Weigh 120 g of magnesium sulfate powder (particle size 2 - 3 mm) and 200 g of sodium bicarbonate (particle size 180 - 200 μm), dissolve them in 1.2 L of deionized water, and stir evenly.

[0053] 2) Add carbon powder: Add 24 g of graphite powder (20% of the mass of magnesium sulfate) to the mixed solution, stir evenly to ensure that the graphite powder is evenly dispersed.

[0054] 3) Hydrothermal reaction: Transfer the mixed solution to a hydrothermal reaction kettle, set the reaction temperature to 200 °C, the reaction time to 16 hours, and the pressure in the reaction kettle will naturally increase to 6 MPa.

[0055] 4) Product separation: After the reaction is completed, cool to room temperature, filter to collect the magnesium hydroxide precipitate, and wash it with deionized water multiple times to remove residual sodium sulfate and other impurities.

[0056] 5) Calcination: Put the washed magnesium hydroxide precipitate into a tube furnace, set the calcination temperature to 500 °C, after heating to the set temperature, keep it calcined at a constant temperature for 2.5 hours, and water vapor is released during the calcination process.

[0057] 6) Cooling: After the calcination is completed, cool the product to room temperature.

[0058] 7) Crushing and screening: Crush and screen the cooled magnesium oxide to obtain magnesium oxide powder with uniform particle size.

[0059] Performance indicators of magnesium oxide in the examples

[0060] Example 1:

[0061]

[0062]

[0063] Example 2:

[0064]

[0065] Performance Index Description:

[0066] 1) Purity: The purity of magnesium oxide is analyzed by X-ray fluorescence spectroscopy (XRF) to ensure high magnesium oxide content and low impurity content in the product.

[0067] 2) Particle Size Distribution: The particle size distribution of magnesium oxide is measured using a laser particle size analyzer. The uniform particle size distribution helps to improve the dispersibility and application performance of the product.

[0068] 3) Specific Surface Area: The specific surface area of magnesium oxide is measured by a specific surface area analyzer (BET method). A moderate specific surface area helps to improve its compatibility in composite materials.

[0069] 4) Whiteness: The whiteness of magnesium oxide is measured using a whiteness meter. Products with high whiteness have better appearance effects in applications such as coatings and plastics.

[0070] 5) Oil Absorption Value: The oil absorption value of magnesium oxide is measured according to the national standard GB / T 1761-1989. A lower oil absorption value indicates better filling performance of the product in composite materials.

[0071] 6) pH Value: The pH value of magnesium oxide is measured by potentiometric titration to ensure that it is within the alkaline range and suitable for various application environments.

[0072] 7) Loss on Ignition: The loss on ignition of magnesium oxide is measured by thermogravimetric analysis (TGA). A low loss on ignition indicates low impurity content and high purity of the product.

[0073] 8) Impurity Content: The impurity content in magnesium oxide is analyzed using ICP-MS to ensure low impurity content such as sulfate ions and sodium ions, and to improve the purity and performance of the product.

[0074] 9) Crystal Structure: The crystal structure of magnesium oxide is analyzed by X-ray diffraction (XRD) to ensure that it has a typical hexagonal crystal system structure, guaranteeing the stability of its physical and chemical properties.

[0075] 10) Electrical Conductivity: The electrical conductivity of magnesium oxide is measured by the four-probe method. Low electrical conductivity indicates good insulation performance of the product.

[0076] 11) Heat Resistance: The heat resistance of magnesium oxide is measured by thermogravimetric analysis (TGA) to ensure good stability in high-temperature environments.

[0077] Performance Advantages

[0078] 1) High Purity: Through hydrothermal reaction and calcination processes, impurities are effectively removed to prepare high-purity magnesium oxide, meeting the requirements of high-end applications.

[0079] 2) Uniform particle size: The uniform particle size distribution helps to improve the dispersibility and application performance of magnesium oxide in the composite material.

[0080] 3) High whiteness: Products with high whiteness have better appearance effects in applications such as coatings and plastics, enhancing the added value of the products.

[0081] 4) Low oil absorption value: A low oil absorption value indicates that magnesium oxide has better filling performance in the composite material, reducing production costs.

[0082] 5) High heat resistance: Magnesium oxide has good heat resistance and is suitable for high-temperature environments, broadening its application scope.

[0083] 6) Low impurity content: Through strict process control, it is ensured that the impurity content in the product is low, improving the purity and performance stability of the product.

[0084] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and basic spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing magnesium oxide from magnesium sulfate, characterized in that, The specific steps include: 1) Mix the solution: Dissolve magnesium sulfate powder and baking soda in deionized water and stir evenly. 2) Add carbon powder: Add graphite powder to the solution and disperse the graphite powder evenly. 3) Hydrothermal reaction: Transfer the mixed solution to a hydrothermal reactor; the reaction temperature of the reactor is 160 - 230 °C, the reaction time is 10 - 20 hours, and the pressure inside the reactor is 2 - 8 MPa. 4) Product separation: After the reaction is completed, cool it to room temperature; filter the reaction product and collect the generated magnesium hydroxide precipitate; wash the precipitate to remove residual sodium sulfate and other impurities. 5) Calcination: Calcinate the washed magnesium hydroxide precipitate, the calcination temperature is 350 - 600 °C; after heating to the set temperature, keep it at a constant temperature for calcination, and the calcination time is 2 - 4 hours; magnesium oxide is generated, and water vapor is released during the calcination process. 6) Cooling: After the calcination is completed, take out the calcined magnesium oxide and cool it to room temperature. 7) Crushing and screening: Crush and screen the cooled magnesium oxide to obtain magnesium oxide powder.

2. The method for preparing magnesium oxide from magnesium sulfate according to claim 1, characterized in that, The mass ratio of the magnesium sulfate to the baking soda is 1:(1 - 2), the particle size of the magnesium sulfate is 1 - 4 mm, and the particle size of the baking soda is 150 - 200 μm.

3. A method for preparing magnesium oxide from magnesium sulfate according to claim 1, characterized in that, The addition amount of the carbon powder is 10% - 20% of the mass of the magnesium sulfate, stir evenly to ensure that the carbon powder is dispersed evenly.

4. A method for preparing magnesium oxide from magnesium sulfate according to claim 1, characterized in that, The calcination is carried out using a muffle furnace or a tube furnace.

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