Tell clearly at once: what is the difference between heavy calcium, light calcium, active calcium, and nano calcium?

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　Calcium carbonate is an important inorganic chemical products and functional powder materials, because of its excellent and unique physical and chemical properties, and a wide range of sources, low price, has been widely used in roads, building materials, metallurgy, rubber, plastics, paper, coatings and other industries.

　　At present, the calcium carbonate products on the market mainly include heavy calcium carbonate, light calcium carbonate, active calcium carbonate and nano calcium carbonate.

　　

　　1. Types of calcium carbonate

　　Lightweight calcium carbonate (precipitated calcium carbonate), referred to as light calcium, is calcined with limestone as raw material to generate lime (calcium oxide) and carbon dioxide, add water to digest to generate lime milk (calcium hydroxide), and then pass into carbon dioxide to generate calcium carbonate precipitation, and finally through dehydration, drying and crushing. The sedimentation volume of light calcium carbonate is 2.4 to 2.8 mL/g.

　　Heavy calcium carbonate, referred to as heavy calcium, is a mechanical method of natural calcium carbonate minerals, such as calcite, limestone, chalk, shells, etc., crushed and processed to the appropriate particle size of the product. The sedimentation volume of heavy calcium carbonate is 1.1~1.4mL/g.

　　Active calcium carbonate, also known as modified calcium carbonate, colloidal calcium carbonate, referred to as living calcium. The use of surface modifiers (coupling agents, stearic acid, etc.), the surface modification of light calcium carbonate or heavy calcium carbonate particles is prepared, and the surface-modified calcium carbonate has a reinforcing effect, that is, the so-called "activity", so it is customary to call the modified calcium carbonate also called active calcium carbonate.

　　Nano calcium carbonate, referred to as nano calcium, is the use of carbonization method to calcinate the selected limestone, the obtained calcium oxide, the calcium hydroxide generated by its digestion will be crushed under high shear action, removed impurities, through carbon dioxide to obtain calcium carbonate slurry, through dehydration, drying, surface treatment prepared.

　　2. The difference between heavy calcium and light calcium

　　Bulk density: The biggest difference between heavy calcium and light calcium is the difference in bulk density, heavy calcium is larger, generally 0.8 ~ 1.3g / cm3, light calcium bulk density is small, generally 0.5 ~ 0.7g / cm3.

　　Whiteness: Heavy calcium has more relative impurities, and the whiteness of products is generally 89% to 93%, and it is rare to reach 95% of products. The light calcium is a chemically synthesized product, removing a lot of impurities, and obtaining a high purity of the product, with a whiteness of 92% to 95%, and a higher whiteness of 96% to 97%, or even higher.

　　Main flow: from the perspective of fluidity, the microstructure of light calcium is spindle shape, and its oil absorption value is larger, so its main flow is obviously not as good as heavy calcium, and it generally adds more than 25 parts to the formula to affect the fluidity of the mixture. In contrast, heavy calcium is irregular granular, which promotes the fluidity of the mixture, and the amount of heavy calcium added can be significantly improved under the condition that some physical properties of the product are relaxed.

　　Moisture content: heavy calcium products have a low moisture content, but also more stable, generally 0.2% to 0.3%; light calcium moisture content is generally 0.3% to 0.8%.

　　3. The difference between active calcium and inactive calcium (ordinary calcium).

　　Hydrophobicity: The surface of active calcium has obvious hydrophobic properties after being coated with an activator. Active calcium and inactive calcium can be identified after dissolving into water.

　　Fluidity: The surface of active calcium is coated by organic active agent molecules with low surface tension, and its surface energy is lower than that of inactivated calcium, and the viscosity resistance between particles is reduced, which significantly improves the fluidity of the active calcium powder, and also marks the difference in product dispersion (compared under the same conditions).

　　Particle size: Because the active calcium surfactant reduces the surface energy of the particles, the particle agglomeration is significantly weakened, the particle size is significantly reduced, and the difference between the two products is resolved by electron microscopy.

　　Oil absorption value: Because the particle size of active calcium is reduced, the void rate between particles is also correspondingly reduced, so that the microscopic surface of the particles is smooth and flat. Therefore, the absorption value of active calcium is lower than that of inactive calcium.

　　Source: Xu Lin. The application of calcium carbonate performance in UPVC extrusion products[J].Plastic Additives, 2020(03):45-46+44", edited by powder technology network, please indicate the source!