阅读说明：本技术 一种液相结晶法制备碱式碳酸镁工艺 (Process for preparing basic magnesium carbonate by liquid-phase crystal method ) 是由 黎敏 于 2019-12-18 设计创作，主要内容包括：本发明提供了一种液相结晶法制备碱式碳酸镁工艺,制备步骤如下：1)取一定量的硫酸镁溶液加入容器后,放入恒温水浴中,持续搅拌并缓慢加入碳酸钠溶液进行复分解反应；2)待反应结束后,将反应后的产物置于高温下静置热解；3)热解一段时间后,降至室温,过滤,用水和乙醇洗涤,除去溶液中生成的硫酸钠,在滤液中加入氯化钡溶液搅拌；4)最后将产物置于一定温度的干燥箱内干燥24h,即得碱式碳酸镁；与现有的碳化法制备碱式碳酸镁相比,本发明可在较低温度下合成粒径较小的球形碱式碳酸镁,并且产物分布均匀、形貌特征优良。(The invention provides a process for preparing basic magnesium carbonate by a liquid-phase crystal method, which comprises the following steps: 1) adding a certain amount of magnesium sulfate solution into a container, putting into a constant-temperature water bath, continuously stirring, and slowly adding a sodium carbonate solution for carrying out double decomposition reaction; 2) after the reaction is finished, placing the product after the reaction at high temperature for standing pyrolysis; 3) pyrolyzing for a period of time, cooling to room temperature, filtering, washing with water and ethanol to remove sodium sulfate generated in the solution, adding barium chloride solution into the filtrate, and stirring; 4) finally, placing the product in a drying oven at a certain temperature for drying for 24 hours to obtain basic magnesium carbonate; compared with the prior art for preparing basic magnesium carbonate by a carbonization method, the method can synthesize spherical basic magnesium carbonate with smaller particle size at lower temperature, and the product has uniform distribution and excellent morphological characteristics.)

1. A process for preparing basic magnesium carbonate by a liquid-phase crystal method comprises the following steps:

(1) adding a certain amount of magnesium sulfate solution into a container, putting into a constant-temperature water bath, continuously stirring, and slowly adding a sodium carbonate solution for carrying out double decomposition reaction;

(2) after the reaction is finished, placing the product after the reaction at high temperature for standing pyrolysis;

(3) pyrolyzing for a period of time, cooling to room temperature, filtering, washing with water and ethanol to remove sodium sulfate generated in the solution, adding barium chloride solution into the filtrate, and stirring;

(4) and finally, placing the product in a drying oven at a certain temperature for drying for 24 hours to obtain the basic magnesium carbonate.

2. The process for preparing basic magnesium carbonate by the liquid phase crystallization method according to claim 1, wherein the temperature of the thermostatic waterbath in the step (1) is 20-60 ℃.

3. The process for preparing basic magnesium carbonate by the liquid phase crystallization method according to claim 1, wherein the metathesis reaction in the step (1) can be completed under the ultrasonic irradiation.

4. The process for preparing basic magnesium carbonate by the liquid-phase crystallization method according to claim 1, wherein the reaction time in the step (2) is 15min to 30 min.

5. The process for preparing basic magnesium carbonate by the liquid phase crystal method according to claim 1, wherein the pyrolysis temperature in the step (2) is 95-130 ℃.

6. The process for preparing basic magnesium carbonate by the liquid phase crystal method according to claim 1, wherein the pyrolysis time in the step (3) is 2-4 h.

Technical Field

The invention relates to the field of inorganic magnesium products, in particular to a process for preparing basic magnesium carbonate by a liquid-phase crystal method.

Background

Basic magnesium carbonate is the most common magnesium compound in industry, and is often applied to the fields of flame retardance, medicines, foods, electronics, military industry and the like due to excellent dispersibility, high elastic modulus, good mechanical properties, good filling property and the like. The basic magnesium carbonate is a nontoxic and harmless substance, only generates water and carbon dioxide through thermal decomposition at high temperature, does not generate other pollutants, absorbs a large amount of heat, has the advantage of environmental protection compared with other halogen-containing flame retardants, and is called as a novel flame retardant.

Along with the development of magnesium ores and the wide application of magnesium materials in China, the demand of magnesium products is gradually increased. Magnesium compounds, in particular magnesium carbonate trihydrate (MgCO), are one of the compounds commonly used in industry ₃·3H ₂O) and basic magnesium carbonate (4 MgCO) ₃·Mg(OH) ₂·4H ₂O) a magnesium compound based on the above-mentioned metal. Widely applied to flame retardant materials, water-based coatings and solidThe additive of materials such as bulk plastics, building base materials, agricultural fertilizers, foods and the like can also be used for treating and decoloring the smoke-removing and desulfurization wastewater of steel and coal.

In the process of preparing basic magnesium carbonate by a liquid phase crystallization method, the basic magnesium carbonate is widely applied due to the advantages of high synthesis efficiency, convenient operation, good appearance, uniform dispersion and the like of a synthesized product, but the conventional method for preparing the basic magnesium carbonate is a carbonization method (CN105936513A), and the basic magnesium carbonate is prepared by other methods by fresh people.

Disclosure of Invention

The invention provides a process for preparing basic magnesium carbonate by a liquid-phase crystal method, aiming at solving the problem that the conventional basic magnesium carbonate preparation method is single, spherical basic magnesium carbonate with smaller particle size is synthesized at lower temperature, and the product is uniform in distribution and excellent in morphological characteristics.

The invention provides a process for preparing basic magnesium carbonate by a liquid-phase crystal method, which comprises the following steps:

(1) adding a certain amount of magnesium sulfate solution into a container, putting into a constant-temperature water bath, continuously stirring, and slowly adding a sodium carbonate solution for carrying out double decomposition reaction;

(2) after the reaction is finished, placing the product after the reaction at high temperature for standing pyrolysis;

(3) after pyrolysis for a period of time, cooling to room temperature, filtering, washing with water and ethanol, removing sodium sulfate generated in the solution, adding a barium chloride solution into the filtrate, stirring, and washing if no precipitate is generated;

(4) and finally, placing the product in a drying oven at a certain temperature for drying for 24 hours to obtain the basic magnesium carbonate, wherein the drying temperature is not too high, and the high-temperature decomposition of the product is prevented.

Preferably, the temperature of the thermostatic water bath in the step (1) is 20-60 ℃.

Preferably, the metathesis reaction in step (1) can also be completed under ultrasonic irradiation, wherein the metathesis reaction is as follows: MgSO (MgSO) ₄+Na ₂CO ₃+3H ₂O→MgCO ₃·3H ₂O+Na ₂SO ₄。

Preferably, the reaction time in step (2) is 15min to 30 min.

Preferably, the pyrolysis temperature in step (2) is 95 ℃ to 130 ℃, wherein the pyrolysis reaction is: 5MgCO ₃·3H ₂O+2H ₂O→4MgCO ₃·Mg(OH) ₂·4H ₂O+CO ₂↑。

Preferably, when the pyrolysis temperature exceeds 100 ℃, the reaction solution will boil and will not reach the set temperature, and the metathesis reaction product is placed in the hydrothermal kettle, and the hydrothermal kettle is placed in the oven, so as to reach the pyrolysis temperature.

Preferably, the pyrolysis time in step (3) is 2h to 4 h.

Compared with the prior art, the invention provides a process for preparing basic magnesium carbonate by a liquid-phase crystallization method, which adopts two liquid-phase crystallization methods to prepare the basic magnesium carbonate, magnesium sulfate and sodium carbonate are subjected to double decomposition reaction under stirring to generate an intermediate product, namely magnesium trihydrate, wherein the magnesium trihydrate is in a rod-shaped structure and is unstable and can be pyrolyzed into the basic magnesium carbonate at high temperature; the prepared basic magnesium carbonate is of a flaky structure, is easy to self-assemble and forms a flaky superposed or spherical structure; the magnesium sulfate and the sodium carbonate are subjected to double decomposition reaction under ultrasonic radiation to generate the magnesium carbonate trihydrate, which has a small irregular nano particle structure and can be pyrolyzed into spherical basic magnesium carbonate at a lower temperature.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.