Method for preparing active magnesium oxide by taking magnesium hydroxide as precursor

Abstract

The invention relates to the technical field of preparation of active magnesium oxide, in particular to a method for preparing active magnesium oxide by taking magnesium hydroxide as a precursor, which comprises the following steps: 1) preparation of light-burned magnesium powder: crushing the light-burned magnesium powder until the particle size is less than or equal to 100 meshes; 2) water milling treatment: adding the crushed caustic-burned magnesia powder into water, and carrying out water milling treatment to obtain magnesium hydroxide slurry; 3) separating and washing: filtering and separating the magnesium hydroxide slurry subjected to water milling to obtain a magnesium hydroxide solid; washing the magnesium hydroxide solid with deionized water to remove surface impurities; 4) drying treatment: drying the washed magnesium hydroxide solid to obtain dried magnesium hydroxide; 5) carbonization treatment: mixing the dried magnesium hydroxide with deionized water according to a solid-to-liquid ratio of 1: (9-11) to generate a magnesium bicarbonate solution; 6) pyrolysis and calcination treatment: carrying out pyrolysis reaction on the magnesium bicarbonate solution to obtain basic magnesium carbonate; and calcining the basic magnesium carbonate to obtain the active magnesium oxide.

Description

Technical Field

[0001] The present invention relates to the technical field of preparing active magnesium oxide, and particularly to a method for preparing active magnesium oxide using magnesium hydroxide as a precursor. Background Art

[0002] Traditional preparation of active magnesium oxide mostly adopts the direct calcination method of magnesite, which has problems such as high energy consumption (800 - 1000 °C), low specific surface area of the product (usually < 50 m 2 / g), and unstable activity index.

[0003] Currently, there is also the use of the acid-base synergistic method, that is, magnesite + sulfuric acid impregnation + calcium hydroxide precipitation, and magnesium hydroxide carbonization to prepare active magnesium oxide. Although the specific surface area and activity index of the product have been improved, the process flow is complex and the production cost is relatively high, which is not conducive to production and promotion. Summary of the Invention

[0004] To overcome the defects of the prior art, the technical problem solved by the present invention is to provide a method for preparing active magnesium oxide using magnesium hydroxide as a precursor. This method uses magnesium hydroxide prepared by the water milling method of light burned magnesium powder to prepare active magnesium oxide, with a simplified process flow and is conducive to cost control.

[0005] To achieve the above purpose, the present invention is realized by adopting the following technical solutions:

[0006] A method for preparing active magnesium oxide using magnesium hydroxide as a precursor, comprising the following steps:

[0007] 1) Preparation of light burned magnesium powder: Crush the light burned magnesium powder to a particle size ≤ 100 mesh;

[0008] 2) Water milling treatment: Add the crushed light burned magnesium powder into water for water milling treatment to obtain a magnesium hydroxide slurry;

[0009] 3) Separation and washing: Filter and separate the water milled magnesium hydroxide slurry to obtain magnesium hydroxide solid; Wash the magnesium hydroxide solid with deionized water to remove surface impurities until the washing liquid is neutral;

[0010] 4) Drying treatment: Perform drying treatment on the washed magnesium hydroxide solid to obtain dried magnesium hydroxide;

[0011] 5) Carbonization treatment: Mix the dried magnesium hydroxide with deionized water at a solid-liquid ratio of 1:(9 - 11) to generate a magnesium bicarbonate solution;

[0012] 6) Pyrolysis and calcination treatment: Heat the magnesium bicarbonate solution to 35 - 45 °C for pyrolysis reaction to obtain basic magnesium carbonate; After calcination treatment of the basic magnesium carbonate, active magnesium oxide is obtained.

[0013] In step 1), in the light-burned magnesium powder, the MgO content is ≥ 85%.

[0014] In step 2), the mass ratio of water to light-burned magnesium powder is (5 - 10):1, the water-grinding time is 2 - 4 hours, and the rotation speed is 200 - 400 r / min.

[0015] In step 4), the drying temperature is 80 - 120 °C, and the drying time is 4 - 6 hours.

[0016] In step 4), the flow rate of the CO2 gas introduced is 0.5 - 1 L / min, the reaction temperature is controlled at 40 - 60 °C, the stirring speed is 300 - 400 r / min, and the stirring reaction is carried out for 2 - 4 hours.

[0017] In step 6), the pyrolysis time is 2 - 3 hours, the calcination temperature is 600 - 800 °C, and the calcination time is 1 - 2 h.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1) The whole process of the present invention is simple, the operating conditions are mild, high-temperature calcination is not required, the energy consumption is low, and it is beneficial to control the cost.

[0020] 2) In the present invention, by water-grinding to refine the particles and washing several times to remove impurities, the reaction activity of the magnesium hydroxide precursor is improved, and the finally prepared magnesium oxide has a high specific surface area and controllable activity. Specific Embodiments

[0021] The following further describes the specific embodiments of the present invention:

[0022] Example 1

[0023] A method for preparing active magnesium oxide using magnesium hydroxide as a precursor, comprising the following steps:

[0024] 1) Preparation of light-burned magnesium powder: The light-burned magnesium powder is crushed to a particle size of ≤ 100 mesh. In the light-burned magnesium powder, the MgO content is ≥ 85%, and 85 light-burned magnesium powder can be selected.

[0025] 2) Water-grinding treatment: The crushed light-burned magnesium powder is added to water for water-grinding treatment to obtain a magnesium hydroxide slurry; the mass ratio of water to light-burned magnesium powder is 8:1, the water-grinding time is 3 hours, and the rotation speed is 300 r / min.

[0026] 3) Separation and washing: The water-ground magnesium hydroxide slurry is filtered and separated to obtain magnesium hydroxide solid; the magnesium hydroxide solid is washed with deionized water to remove surface impurities until the washing liquid is neutral;

[0027] 4) Drying: Drying the washed magnesium hydroxide solid to obtain dry magnesium hydroxide;

[0028] The drying temperature was 100°C, the drying time was 5 hours, the flow rate of CO2 gas was 0.8 L / min, the reaction temperature was controlled at 50°C, the stirring speed was 350 r / min, and the stirring reaction was carried out for 2.5 hours.

[0029] 5) Carbonization treatment: Mix the dried magnesium hydroxide with deionized water at a solid-liquid ratio of 1:10 to generate a magnesium bicarbonate solution;

[0030] 6) Pyrolysis and Calcination: The magnesium bicarbonate solution is heated to 40°C and pyrolyzed to produce basic magnesium carbonate. The basic magnesium carbonate is calcined to produce activated magnesium oxide. The pyrolysis time is 2.5 hours, and the calcination temperature is 650°C for 2 hours.

[0031] Example 2

[0032] A method for preparing active magnesium oxide using magnesium hydroxide as a precursor comprises the following steps:

[0033] 1) Preparation of light-burned magnesium powder: crush the light-burned magnesium powder to a particle size of ≤100 mesh. The MgO content in the light-burned magnesium powder is ≥85%. 85 light-burned magnesium powder can be used.

[0034] 2) Water milling: The crushed light-burned magnesium powder was added to water and water milled to obtain magnesium hydroxide slurry; the mass ratio of water to light-burned magnesium powder was 5:1, the water milling time was 2.5 hours, and the rotation speed was 250 r / min.

[0035] 3) Separation and washing: filtering and separating the water-milled magnesium hydroxide slurry to obtain magnesium hydroxide solid; washing the magnesium hydroxide solid with deionized water to remove surface impurities until the washing liquid is neutral;

[0036] 4) Drying: Drying the washed magnesium hydroxide solid to obtain dry magnesium hydroxide;

[0037] The drying temperature was 90°C, the drying time was 4.5 hours, the flow rate of CO2 gas was 0.6 L / min, the reaction temperature was controlled at 45°C, the stirring speed was 300 r / min, and the stirring reaction was carried out for 3 hours.

[0038] 5) Carbonization treatment: Mix the dried magnesium hydroxide with deionized water at a solid-liquid ratio of 1:10 to generate a magnesium bicarbonate solution;

[0039] 6) Pyrolysis and calcination treatment: Heat the magnesium bicarbonate solution to 42 °C for pyrolysis reaction to obtain basic magnesium carbonate; after calcining the basic magnesium carbonate, active magnesium oxide is obtained. Among them, the pyrolysis time is 3 hours, the calcination temperature is 700 °C, and the calcination time is 1.5 h.

[0040] 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 belong to the protection scope of the present invention. In addition, it should be noted that in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe various possible combination methods separately. In addition, 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.

Claims

1. A method for preparing active magnesium oxide using magnesium hydroxide as a precursor, characterized in that, It includes the following steps: 1) Preparation of light-burned magnesium powder: Crush the light-burned magnesium powder to a particle size of ≤100 mesh; 2) Water milling treatment: Add the crushed light-burned magnesium powder into water and conduct water milling treatment to obtain magnesium hydroxide slurry; 3) Separation and washing: Filter and separate the water-milled magnesium hydroxide slurry to obtain magnesium hydroxide solid; Wash the magnesium hydroxide solid with deionized water to remove surface impurities until the washing liquid is neutral; 4) Drying treatment: Conduct drying treatment on the washed magnesium hydroxide solid to obtain dried magnesium hydroxide; 5) Carbonization treatment: Mix the dried magnesium hydroxide with deionized water at a solid-liquid ratio of 1:(9 - 11) to generate magnesium bicarbonate solution; 6) Pyrolysis and calcination treatment: Heat the magnesium bicarbonate solution to 35 - 45 °C for pyrolysis reaction to obtain basic magnesium carbonate; After calcining the basic magnesium carbonate, obtain active magnesium oxide.

2. The method for preparing active magnesium oxide using magnesium hydroxide as a precursor according to claim 1, characterized in that, In the step 1), in the light-burned magnesium powder, the MgO content is ≥85%.

3. A method for preparing active magnesium oxide using magnesium hydroxide as a precursor according to claim 1, characterized in that, In the step 2), the mass ratio of water to light-burned magnesium powder is (5 - 10):1, the water milling time is 2 - 4 hours, and the rotation speed is 200 - 400 r / min.

4. A method for preparing active magnesium oxide using magnesium hydroxide as a precursor according to claim 1, characterized in that, In the step 4), the drying temperature is 80 - 120 °C, and the drying time is 4 - 6 hours.

5. A method for preparing active magnesium oxide using magnesium hydroxide as a precursor according to claim 1, characterized in that, In the step 4), the flow rate of the CO2 gas introduced is 0.5 - 1 L / min, the reaction temperature is controlled at 40 - 60 °C, the stirring speed is 300 - 400 r / min, and the stirring reaction is carried out for 2 - 4 hours.

6. The method for preparing active magnesium oxide using magnesium hydroxide as a precursor according to claim 1, characterized in that, In the step 6), the pyrolysis time is 2 - 3 hours, the calcination temperature is 600 - 800 °C, and the calcination time is 1 - 2 h.