Preparation process of special magnesium oxide

Abstract

The application discloses a preparation process of special magnesium oxide and relates to the technical field of special magnesium oxide preparation, and comprises the following steps: crushing magnesite, processing the magnesite into a plurality of ore blocks, screening the ore blocks with high magnesium content for further crushing, setting the initial rotating speed of a converter, starting the converter and preheating, pouring the ore blocks into the converter, continuously heating the converter, when the temperature and heating time of the converter reach the requirements, stopping the heating and closing the converter, cooling the converter to the ambient temperature, completing the first-time burning of the magnesium oxide, resetting the rotating speed of the converter, starting the converter and heating, when the temperature and heating time of the converter reach the requirements, stopping the heating and closing the converter, cooling the converter to the ambient temperature, taking out the special magnesium oxide after repeated burning, mixing and bagging, and completing the preparation of the special magnesium oxide. The repeated calcination method is adopted, the prepared magnesium oxide has high catalytic performance, and thus the combustion performance of double-base propellant is improved.

Description

Technical Field

[0001] This invention relates to the technical field of special magnesium oxide preparation, specifically a preparation process for special magnesium oxide. Background Technology

[0002] Biaryl magnesium type double-base propellant is a traditional type of double-base propellant that still maintains a certain market demand. Magnesium oxide, as an important raw material in bisaryl magnesium type double-base propellant, plays a catalytic and combustion stabilizing role, which determines the ballistic performance of the propellant.

[0003] Magnesium oxide (MgO) can be prepared by various methods, including brine ammonium carbonate preparation, secondary carbonization, seawater precipitation, chemical synthesis, and magnesite carbonization. The mainstream domestic production method involves chemically purifying the semi-finished product after calcining magnesite powder to remove impurities such as Fe, Al, and Ca, significantly increasing the purity of MgO to over 99%. However, this chemical treatment reduces the catalytic activity of the MgO, and its effect on regulating burning rate in propellants after hydration is limited, failing to meet product requirements. Therefore, it is necessary to break away from traditional MgO calcination methods. Based on this, a special MgO preparation process is designed, employing a repeated calcination method. This process is simpler and faster, producing MgO with higher catalytic performance, thereby improving the combustion performance of dual-base propellants. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a special magnesium oxide preparation process. The process adopts a repeated calcination method, which makes the whole process simpler and faster, and the prepared magnesium oxide has high catalytic performance, thereby improving the combustion performance of double-base propellants and meeting the application requirements of bis(aryl) magnesium-type double-base propellant products.

[0005] The objective of this invention is achieved through the following technical solution: a preparation process for a special magnesium oxide, the preparation process comprising the following steps:

[0006] S1. Crush the magnesite and process it into several ore blocks.

[0007] S2. Screen the ore blocks to select those with high magnesium content.

[0008] S3. Further crush the screened ore blocks until the particle size is 80-120μm. This is mainly to facilitate calcination, increase the calcination area, and improve calcination efficiency.

[0009] S4. Set the initial rotation speed of the converter, turn on the converter and preheat it. When the converter temperature rises to 380℃, pour the further crushed ore blocks into the converter.

[0010] S5. Continue heating the converter until the converter temperature reaches 850-950℃ and the heating time is ≥8 hours. Then, turn off the converter and stop heating. After the converter cools down to ambient temperature, the first firing of magnesium oxide is completed.

[0011] S6. Reset the converter speed, turn on the converter and heat it. When the converter temperature reaches 850-950℃ and the heating time is ≥8 hours, turn off the converter and stop heating. Let the converter cool down to ambient temperature.

[0012] S7. After the special magnesium oxide is repeatedly fired, it is taken out, mixed and bagged to complete the preparation of special magnesium oxide.

[0013] Preferably, in step S1, the magnesite is crushed and processed into several ore blocks with a size of 150-250 mm.

[0014] Preferably, in step S2, the ore blocks are screened to select those with a magnesium content ≥ 42%.

[0015] Preferably, in step S4, the initial rotation speed of the converter is set to 400-450 rpm, the converter is turned on and preheated, and when the converter temperature rises to 380°C, the further crushed ore blocks are poured into the converter.

[0016] Preferably, in step S6, the converter speed is reset to 350-400 rpm, the converter is turned on and heated, and when the converter temperature reaches 850-950℃ and the heating time is ≥8 hours, the converter is turned off and the heating is stopped, and the temperature is cooled to ambient temperature. The heating time is controlled to 8 hours or more because the heating rate cannot be too fast. If the heating rate is too fast, the specific surface area of ​​the MgO particles will be larger, resulting in incomplete, distorted, and defective grains, and no time to produce regular grains. When the thermogravimetric (TG) analysis of the magnesite sample is performed, when the firing temperature reaches about 850-950℃, the mass reduction is 0.72%, indicating that the magnesite is basically completely decomposed and there is no need to further increase the firing temperature. Therefore, the firing temperature is set to 850-950℃.

[0017] The beneficial effects of this invention are:

[0018] This invention employs a repeated calcination method, which makes the entire process simpler and faster, and produces magnesium oxide with high catalytic performance, thereby improving the combustion performance of dual-base propellants and meeting the application requirements of bis(aryl) magnesium-type dual-base propellant products. Attached Figure Description

[0019] Fig. 1 Image of a special type of magnesium oxide;

[0020] Fig. 2 This is a SEM image of a special type of magnesium oxide. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1:

[0024] like Figs. 1-2 As shown, a process for preparing a special type of magnesium oxide includes the following steps:

[0025] S1. Crush the magnesite and process it into several ore blocks with a size of about 200mm.

[0026] S2. Screen the ore blocks to select those with a magnesium content ≥ 42%. If the magnesium content of the magnesite is < 42%, the magnesium oxide content in the produced specialty magnesium oxide will be less than 85%, which cannot meet product requirements. Specialty magnesium oxide requires a magnesium oxide content ≥ 85%.

[0027] S3. The screened ore blocks are further crushed until the particle size is 120μm. This is mainly to facilitate calcination, increase the calcination area, and improve the calcination efficiency.

[0028] S4. Set the initial rotation speed of the converter to 400 r / h, start the converter and preheat it. When the converter temperature rises to 380℃, pour the further crushed ore blocks into the converter. Since magnesite generally begins to decompose at around 350-380℃ when heated, releasing CO2 and generating MgO, the preheating temperature is set to 380℃.

[0029] S5. Continue heating the converter until it reaches 900℃ and the heating time reaches 8.5 hours. Then, turn off the converter and stop heating. After the converter cools to ambient temperature, the first firing of magnesium oxide is complete. The first firing uses a method of heating while the converter is rotating to ensure that the ore blocks in the converter are heated more evenly.

[0030] S6. Reset the converter speed to 350 r / h, turn on the converter and heat it. When the converter temperature reaches 900℃ and the heating time reaches 8 hours, turn off the converter and stop heating. Let the converter cool to ambient temperature. The repeated firing stage controls the loss on ignition of magnesium oxide by controlling the converter speed. According to Table 1, when the speed is 350-400 r / h, the loss on ignition of magnesium oxide meets the technical requirements.

[0031]

[0032]

[0033] Table 1

[0034] S7. After the special magnesium oxide is repeatedly fired, it is taken out, mixed and bagged to complete the preparation of special magnesium oxide.

[0035] In the existing technology, chemical treatment is usually used to prepare magnesium oxide. The magnesium oxide prepared by chemical treatment and magnesium oxide prepared by repeated calcination were sampled and analyzed separately. The comparison results are shown in Table 2.

[0036]

[0037] Table 2. Comparison of test results for magnesium oxide prepared by chemical method and repeated calcination method.

[0038] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A process for preparing a special type of magnesium oxide, characterized in that: Includes the following steps: S1. Crush the magnesite and process it into several ore blocks; S2. Screen the ore blocks to select those with a magnesium content ≥ 42%; S3. Further crush the screened ore blocks until the particle size is 80-120μm; S4. Set the initial rotation speed of the converter to 400-450 rpm, turn on the converter and preheat it. When the converter temperature rises to 380℃, pour the further crushed ore blocks into the converter. S5. Continue to heat the converter until the converter temperature reaches 850-950℃ and the heating time is ≥8 hours. Then, turn off the converter and stop heating. After the converter cools down to the ambient temperature, the first firing of magnesium oxide is completed. S6. Reset the converter speed to 350-400 rpm, turn on the converter and heat it. When the converter temperature reaches 850-950℃ and the heating time is ≥8 hours, turn off the converter and stop heating. Let the converter cool down to ambient temperature. S7. After the special magnesium oxide is repeatedly fired, it is taken out, mixed and bagged to complete the preparation of special magnesium oxide.

2. The preparation process of a special magnesium oxide according to claim 1, characterized in that: In step S1, the magnesite is crushed and processed into several ore blocks with a size of 150~250mm.

3. The preparation process of a special magnesium oxide according to claim 1, characterized in that: The initial rotation speed of the converter is set to 400 rpm. The converter is turned on and preheated. When the converter temperature rises to 380°C, the further crushed ore blocks are poured into the converter. The converter continues to be heated. When the converter temperature reaches 900°C and the heating time reaches 8.5 hours, the converter is turned off and the heating is stopped. After the converter cools down to ambient temperature, the first firing of magnesium oxide is completed.

4. The preparation process of a special magnesium oxide according to claim 1, characterized in that: Reset the converter speed to 350 r / h, turn on the converter and heat it. When the converter temperature reaches 900℃ and the heating time reaches 8h, turn off the converter and stop heating. Let the converter cool down to ambient temperature.

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