Lightweight calcium carbonate and heavyweight calcium carbonate differ significantly in terms of their sources, bulk density, whiteness, moisture content, particle size, particle shape, crystal form, oil absorption value, fluidity, price and application fields. The details are as follows: 

Source method: Lightweight calcium carbonate is produced through chemical synthesis. For example, limestone is calcined to produce lime and carbon dioxide, which is then digested with water to form lime milk. Carbon dioxide is introduced to carbonize it, resulting in calcium carbonate precipitation. This is then dehydrated, dried, and ground into powder. Heavy calcium carbonate is produced by directly crushing natural calcite, marble, chalk, and shells using mechanical methods. 

Bulk density: The bulk density of heavy calcium carbonate is relatively high, typically ranging from 0.8 to 1.3 g/cm³; the bulk density of light calcium carbonate is relatively low, usually around 0.5 to 0.7 g/cm³; some nano calcium carbonate products have even lower bulk densities, reaching approximately 0.28 g/cm³. 

Whiteness: Due to the relatively high content of impurities, the whiteness of heavy calcium carbonate is generally 89% - 93%, with only a very small number of products reaching 95%. The light calcium carbonate products have high purity and the whiteness is mostly 92% - 95%, and some products can reach 96% - 97%. 

Water content: The water content of heavy calcium carbonate products is generally 0.2% - 0.3%. The water content is relatively low and stable. Some high-end heavy calcium carbonate products can even have a water content of around 0.1%. The water content of ordinary light calcium carbonate products is 0.3% - 0.8%, and there may be some fluctuations and instability. 

Particle size: The particle size of heavy calcium carbonate products ranges from 0.5 to 45 μm. The particle size of ordinary light calcium carbonate products is generally 0.5 to 15 μm. The primary particles of light nano calcium carbonate are usually 80-120 nm in size and are prone to agglomeration. After agglomeration, the particles are much larger than the original particles. 

Particle shape: The shapes of heavy calcium carbonate particles are generally irregular, such as cubes, polyhedrons, rectangular prisms, etc. The particles of heavy calcium carbonate are generally in an irregular shape. The primary particles of light calcium have a more regular shape, including spindle-shaped, spherical, and cubic shapes, but the aggregated particles are irregular. 

Crystal form: Heavy calcium carbonate has a fixed crystal shape. Fragmentation and refinement will not change the crystal form. Generally, calcite heavy calcium carbonate is of hexagonal crystal form, and marble heavy calcium carbonate is of cubic crystal form. In the specific carbonation process for preparing light calcium carbonate, three types of calcium carbonate in different proportions will simultaneously appear. To obtain a single and pure certain crystal form, the molding process needs to be controlled. 

Oil absorption value: The oil absorption value of light-weight calcium carbonate is 60-90 ml/100mg, which is much higher than that of heavy-weight calcium carbonate (15-35 ml/100mg). 

Flowability: The flowability of light-weight calcium carbonate is not as good as that of heavy-weight calcium carbonate. Generally, if the addition amount exceeds 25 parts, it will seriously affect the flowability. While heavy-weight calcium carbonate is in a granular form, it can promote flowability, but excessive addition will affect the flowability. 

Price: The price of heavy calcium carbonate of the same particle size is lower than that of light calcium carbonate. 

Application fields: Heavy calcium carbonate is mainly used in industries such as papermaking, rubber, and plastics, with a relatively large filling volume. It is mainly used as a volume filler to reduce the manufacturing cost of the products. Light calcium carbonate has a wider application range, mainly used in plastics, rubber, coatings, adhesives, cigarette paper, ink, etc., mainly for volume filling. While nano calcium carbonate products are often used as functional fillers such as modification or reinforcement during application, the filling volume is generally smaller. Both heavy and light calcium carbonate application fields are very similar. Light nano calcium is not only used for physical filling but also for functional reinforcement.