How to distinguish between light calcium carbonate and heavy calcium carbonate?

Calcium carbonate can not only reduce the raw material cost of plastic products, but also improve some properties of plastic materials. In recent years, gratifying achievements have been made. The research results of many universities and scientific research institutions show that if used properly, different types of calcium carbonate can significantly improve the performance of matrix plastics. However, the difference between light calcium carbonate and heavy calcium carbonate has always bothered most users.


The differences are as follows:

1. Different sources

Light calcium carbonate is chemically synthesized calcium carbonate, also known as precipitated calcium carbonate, colloidal calcium carbonate or activated calcium carbonate. It can even produce nano-sized calcium carbonate, called light calcium. The limestone raw material is calcined to produce lime and carbon dioxide, and then water is added to digest the lime to produce lime milk. Its main component is calcium hydroxide, calcium hydroxide is introduced into carbon dioxide to carbonize lime milk to form calcium carbonate precipitate. After dehydration, drying, crushing or double decomposition reaction of sodium carbonate and calcium chloride to form calcium carbonate precipitate, it is dehydrated, dried and crushed. Heavy calcium carbonate, referred to as heavy calcium, is directly crushed natural calcite, marble, chalk and shells by mechanical methods.

2. Different bulk density

The obvious difference between heavy calcium carbonate and light calcium is the different bulk density of the product. The bulk density of heavy calcium products is relatively large, generally 0.8-1.3g/cm3; the bulk density of light calcium products is relatively small, mostly 0.5-0.7g/cm3; and the bulk density of some nano calcium carbonate products is lower, reaching about 0.28g/cm3. Heavy calcium and light calcium products can also be roughly distinguished by the packaging volume of the product. Generally speaking, the packaging capacity of heavy calcium products is 25 kg/bag, while the packaging capacity of light calcium products of the same quality is significantly larger. Some nano calcium carbonate products also use 15kg/package or 20kg/package.

3 different whiteness

Due to the large impurity content in heavy calcium carbonate products, the whiteness of the products is generally 89%-93%, and only a few products can reach 95%. The light calcium product adopts chemical synthesis, which removes a large amount of impurities and has high purity. Therefore, the whiteness is mostly 92%-95%, and some products can reach 96%-97%, which is also the main reason why light calcium products are mostly used to fill high-grade or light-colored products.

4 Different water content

The water content of ground calcium carbonate products is generally 0.2-0.3%, which is relatively low and stable. The water content of some high-grade heavy calcium products can even reach about 0.1 percent. The water content of ordinary light calcium products is 0.3-0.8%, sometimes fluctuating and unstable. Traditionally, the difference between heavy calcium and light calcium is to test water with a water instrument. When the water content is close to 1% for light calcium, when the water content is less than 0.1 for heavy calcium.

5. Different particle size

The particle size range of the heavy calcium product is 0.5-45um, and the particle size of the product varies with the crushing equipment. The particle size of ordinary light calcium products is generally 0.5-15um. Because the particle shape is spindle-shaped, it is difficult to accurately measure, generally in a range; the particle size of nano calcium carbonate in light calcium is fine, generally 20-200nm. The particle size of ordinary light calcium carbonate is generally about 2500 mesh, which can meet the performance requirements of PVC pipes and profiles. Therefore, considering the particle size, the traditional PVC pipes and profiles use light calcium carbonate. In the past, due to the limitation of crushing equipment, the fineness is larger. Now the particle size of heavy calcium carbonate can fully meet the needs, even finer than light calcium carbonate. Therefore, PVC pipes and profiles can be selected at present.


Heavy calcium carbonate