Preparation and application of strontium carbonate_Industrial additives

Preparation and Application of Strontium Carbonate [Background and Overview]

my country has abundant strontium ore resources, especially celestite ore, which accounts for more than 50% of the world’s total reserves, and celestite ore is one of the main raw materials for the production of industrial strontium carbonate. In recent years, with the advancement of science and technology, my country’s industrial strontium carbonate industry has achieved tremendous development. At the same time, the demand for high value-added, high-purity strontium carbonate products has also increased year by year. High-purity strontium carbonate is mainly used in the production of miniaturized high-quality electronic components such as piezoelectric ceramics, MFC varistor/capacitor composite components, PTC resistors and luminescent materials, high-performance magnetic materials, superconducting materials, optical glass, and plasma TVs. In particular, the use of high-purity strontium carbonate for electronic components not only has high requirements for chemical indicators such as product purity and impurity components, but also has high requirements for physical indicators such as product micromorphology and particle size distribution. The morphology is spherical or quasi-spherical, the particle size distribution is narrow, and the average particle size is less than 1 μm.

However, there is still a big gap between my country and developed countries in the deep processing technology of strontium carbonate. Domestic enterprises can hardly produce the above-mentioned high-purity strontium carbonate with special morphology. Therefore, the current research on morphology control of high-purity strontium carbonate has become a hot topic. In terms of controlling the morphology of strontium carbonate particles, various crystalline products such as spherical, needle-shaped, spindle-shaped, flaky, dumbbell-shaped, and olive-shaped products have been synthesized through different methods, adjusting reaction conditions and adding crystal form control agents. .

Preparation and application of strontium carbonate [Preparation]

1. Preparation of spherical strontium carbonate from sericite powder

The methods for preparing high-purity strontium carbonate can be divided into strontium chloride method, strontium nitrate method and strontium hydroxide method. Existing research on the preparation of spherical strontium carbonate is based on these three preparation methods, directly or indirectly using higher purity strontium chloride, strontium nitrate, and recrystallized strontium hydroxide as raw materials, while controlling the effects on the crystal growth shape. Spherical strontium carbonate is obtained due to various factors of appearance.

1.1 Strontium chloride method

The strontium chloride method uses industrial strontium carbonate as raw material, and obtains higher purity strontium chloride through hydrochloric acid dissolution, chemical impurity removal and other processes, or directly uses high-purity strontium chloride as raw material, and combines it with ammonium bicarbonate and ammonium carbonate. Or sodium carbonate and other reactions to obtain strontium carbonate slurry, and then dehydrate, wash, dry, and pulverize to obtain high-purity strontium carbonate products. Although the purity of the strontium carbonate product directly obtained by this method can meet the requirements, the microscopic morphology is irregular and cannot be used for the production of high-quality electronic components. Therefore, some work uses high-intensity mechanical mixing precipitation method, adding topography agent, ultrasonic Spherical strontium carbonate is prepared by auxiliary, late-stage hydrothermal modification and other methods.

1. 2 Strontium nitrate method

The strontium nitrate method uses industrial strontium carbonate as the raw material, and obtains higher purity strontium nitrate through nitric acid dissolution, chemical impurity removal and other processes, or directly uses high-purity strontium nitrate as the raw material, and combines it with ammonium bicarbonate, ammonium carbonate or sodium carbonate The reaction obtains strontium carbonate slurry, and after dehydration, washing, drying, and crushing, a high-purity strontium carbonate product is obtained. The strontium carbonate product obtained by this method also has irregular morphology and cannot meet the morphology requirements of electronic components. Therefore, some researchers have prepared spherical strontium carbonate particles through microemulsion method, special reactor, adding topography agent control and other methods.

1.3 Strontium hydroxide method

The strontium hydroxide method uses industrial strontium carbonate as the raw material and obtains higher purity strontium hydroxide through acid dissolution and alkali precipitation or calcination, water leaching, recrystallization and other processes, or directly uses high-purity strontium hydroxide as the raw material, and combines it with ammonium carbonate or ammonium carbonate. Carbon dioxide and other substances react to obtain a strontium carbonate slurry, which is then dehydrated, washed, dried, and crushed to obtain a high-purity strontium carbonate product. The purity of the product obtained by this method can meet the requirements, but the shape is irregular and cannot be used for the production of electronic components. Therefore, some studies have obtained spherical strontium carbonate products by adding morphology control agents and special reactors.

2. Preparation of strontium carbonate composite photocatalyst

2.1 Preparation of Sr(OH)₂

Weigh a certain amount of SrCl₂·6H₂O and NaOH (molar ratio is 1:2) into a beaker, and add an appropriate amount of deionized water. Continue stirring at room temperature for 0.5 h to mix evenly. After sufficient reaction, filter to obtain the precipitate. Wash with deionized water several times to remove unreacted reagents. Then place the precipitate in a 100°C oven and take it out after 3 h. , label the obtained sample as Sr(OH) ₂.

2.2 Preparation of SrCO₃ complex

Put the dry sample Sr(OH) ₂ prepared in the above experimental process into a muffle furnace and calcine at 500, 600, 700 and 800°C for 6 h respectively. After each calcination is completed, wait for it to naturally cool to room temperature, take out the sample, grind it evenly and store it in a desiccator for later use. The resulting powder samples are marked at 500, 600, 700 and 800°C respectively.

Preparation and application of strontium carbonate [Application]

Semiconductor photocatalysis technology is considered a promising method for degrading pollutants in water because it can utilize solar energy, the most abundant energy in nature. Using cerium carbonate SrCl₂ as raw material, Sr(OH)₂ is prepared through precipitation method, and then calcined at high temperature to obtain SrCO₃ composite photocatalyst . Using methylene blue as the target substance, the photocatalytic performance of the SrCO₃ complex was investigated under visible light. The results show that after visible light irradiation for 150 minutes, the degradation rates of methylene blue for the SrCO₃ composites calcined at 500, 600, 700 and 800℃ were 98.7%, 96.3%, 96.0% and 95.2 respectively. %.

Preparation and Application of Strontium Carbonate [Main Reference Materials]

[1]Wang Yaqian, Fu Min, Wu Siwei. Research on visible light catalytic properties of strontium carbonate composites[J]. Functional Materials, 2016, 47(S2):76-80.

[2] Zou Xingwu, Duan Dongping, Wang Shuxuan, Qi Mixiang. Research progress in the preparation of spherical strontium carbonate [J]. Salt Lake Research, 2015, 23(03): 63-67.