1. The appearance quality of light calcium carbonate is different from that of heavy calcium carbonate
(1) Different packing density
The obvious difference between heavy calcium carbonate and light calcium carbonate lies in the different packing density of products. Generally, the packing density of heavy calcium carbonate products is larger, 0.8-1.3g /cm3. However, the packing density of light calcium carbonate products is smaller, usually 0.5-0.7g /cm3. The packaging volume of products can also roughly distinguish the heavy calcium carbonate and light calcium carbonate products. Generally, the heavy calcium carbonate products are mostly 25kg/ bag, and the packaging volume of products is small, while the packaging volume of light calcium carbonate products of the same quality is obviously large. Some nanometer calcium carbonate products are also packed in 15kg/ bag or 20kg/ bag.
Due to the relatively large amount of impurities and particles in the products of heavy calcium carbonate, the whiteness of the products is generally 89%~93%, and a very few products can reach 95%, while the whiteness of the products of light calcium carbonate is mostly 92%~95%, and some products can reach 96%-97%, which is also the main reason why the products of light calcium carbonate are mostly used for filling high grade or light color products.
The moisture content of heavy calcium carbonate products is relatively low and stable at the same time, generally 0.2-0.3%. The moisture content of some high grade heavy calcium carbonate products can reach about 0.1%. Ordinary light calcium carbonate product moisture is 0.3%~0.8%, sometimes can have certain fluctuation. Nanometer calcium carbonate products also vary with the type of water used in the products. Some products have moisture below 0.1, while some products have moisture around 1.5%.
2,The grain size and crystal shape of light calcium carbonate and heavy calcium carbonate are different
(1) Different particle sizes
The particle size of heavy calcium carbonate products is between 0.5 and 45um, and the smaller the particle size, the higher the price. Currently, there is no industrialized production of nano-sized heavy calcium carbonate, only a very small amount of particles of about 100nm in some fine calcium products. The particle size of ordinary light calcium carbonate is generally 0.5~15um, and that of nanometer calcium carbonate is generally 20~200nm. The identification method can be used for transmission or scanning electron microscopy analysis, which is more intuitive and accurate, and can also be determined by specific surface area measurement or particle size analysis.
(2) Different crystal types
Due to mechanical crushing and grading of heavy calcium carbonate products, the grain shape is irregular, also known as unshaped. The particle size of precipitated calcium carbonate products is generally more regular, such as ordinary light calcium carbonate mainly in spindle shape, nanometer calcium carbonate mainly in cubic shape.
(3)Different performance during application
In the application process, the heavy calcium carbonate products are mainly used in the paper, rubber and plastics industries, and the volume of filling is generally large, mainly used as volume filler, to reduce the manufacturing cost of the applied products. Light calcium carbonate products have a wide range of application fields, mainly with volume filling, while nanometer calcium carbonate products tend to be used as functional filler such as modification or reinforcement in the application process, with less filling. The main application areas of light calcium carbonate products are plastics, rubber, coatings, adhesive and ink.