The main factors affecting the preparation of magnesium carbonate from magnesium sulfate include the reaction temperature, the drop acceleration rate of the precipitant, and the initial concentration of the feedstock.
Reaction Temperature
Reaction temperature is one of the key factors affecting the preparation of magnesium carbonate. Studies have shown that when the reaction temperature is lower than 313 K, rod-shaped magnesium carbonate trihydrate (MgCO₃-3H₂O) crystals can be obtained; while when the reaction temperature is higher than 323 K, the product will be changed from magnesium carbonate trihydrate to spherical magnesium carbonate alkali, and the particle size will become larger with the increase of reaction temperature.
In addition, the reaction temperature affects the structure and crystal shape of magnesium basic carbonate. For example, the product prepared at 55~60°C contains about 5 crystalline waters, and the crystal shape is needle-like; the product prepared at 65~70°C contains 6 crystalline waters, and the crystal shape is flocculent and flaky; the product prepared at 75~80°C contains about 8 crystalline waters, and the crystal shape is cotton-stick; the product prepared at 85°C contains 6~7 crystalline waters, and the crystal shape is transitioned from cotton-stick fracture to globular shape; the product prepared at 90~95°C contains 4 crystalline water, and the crystal shape is spherical; the product prepared at 100 ℃ contains about 3 crystalline water, and the spherical structure is broken.
Drop acceleration rate of precipitant
The drop acceleration rate of the precipitant also has a significant effect on the morphology and particle size of the product. When the drip acceleration rate of the precipitant is faster, the magnesium carbonate particles generated are larger; on the contrary, when the drip acceleration rate is slower, the magnesium carbonate particles generated are smaller.
Initial concentration of raw materials
The initial concentration of the raw material also affects the morphology and particle size of the product. When the initial concentration is higher, the generated magnesium carbonate particles are larger; on the contrary, when the initial concentration is lower, the generated magnesium carbonate particles are smaller.
Other influencing factors
In addition to the above factors, the pH of the reaction system, the stirring speed and the reaction time also affect the morphology and particle size of the products. For example, at a higher pH, the generated magnesium carbonate particles are larger; while at a lower pH, the generated magnesium carbonate particles are smaller. In addition, the stirring speed and reaction time also affect the homogeneity and particle size distribution of the product.