The difference between light calcium and heavy calcium

Release date: 2023-11-15

Calcium carbonate can not only reduce the raw material cost of plastic products, but also improve some properties of plastic materials. Research results show that different types of calcium carbonate can significantly improve the performance of base plastics when used properly. So, what is the difference between light calcium and heavy calcium?

Heavy calcium carbonate: Also known as ground calcium carbonate, or heavy calcium for short, it is produced through physical processing using natural calcite, limestone, dolomite, chalk, shells, etc. as raw materials. Light calcium carbonate: also known as precipitated calcium carbonate, or light calcium for short, it is processed by chemical methods. So, what is the difference between light calcium and heavy calcium?

1. Production method

Heavy calcium is mainly a powder material obtained by mechanical grinding of natural minerals such as calcite, marble, limestone, chalk, white marble, etc.

Light calcium is mainly a powder material obtained from limestone as raw material through processes such as calcination, digestion, carbonization, dehydration, drying, and classification.

2. Packing density

The difference in product packing density is the most obvious difference between heavy calcium and light calcium.

The bulk density of heavy calcium products is relatively large, generally 0.8 to 1.3g/cm3.

The bulk density of light calcium products is small, generally 0.5-0.7g/cm3, and the bulk density of some nano-calcium carbonate products can even reach about 0.28g/cm3.

3. Oil absorption value

Due to its large particles, smooth surface, and small specific surface area, heavy calcium has a low oil absorption value, generally 40 to 60 mL/100g.

Light calcium particles are fine, the surface is rough, and the specific surface area is large, so the oil absorption value is high, generally 60 ~ 90mL/100g.

4. Whiteness

Due to the relatively large number of impurities in heavy calcium, the product whiteness is generally 89% to 93%, and very few products can reach 95%.

Light calcium products have high purity, so the whiteness is generally 92% to 95%, and some products can reach 96% to 97%.

5. Moisture content

The moisture content of heavy calcium products is generally 0.2% to 0.3%. The moisture content is relatively low and relatively stable. The moisture content of some high-end products can even reach about 0.1%.

Ordinary light calcium products have a moisture content of 0.3% to 0.8%, which sometimes fluctuates and is unstable.

6. Particle shape

The characteristics of heavy calcium powder are: the particles are irregular in shape, and the particles have certain edges and corners, and the surface is rough. The particle size difference is large, the particle size distribution is wider, and the particle size is larger. Crushing and refining will not change the crystal form of heavy calcium. Generally, calcite heavy calcium is in the hexagonal crystal form and marble heavy calcium is in the cubic crystal form. This is mainly related to the place of origin.

The characteristics of light calcium powder are: the particles have regular shape and can be regarded as monodisperse powder. The particle size distribution is narrow. According to the different grain shapes, light calcium can be divided into spindle, cubic, needle-shaped, chain-shaped, spherical, flaky and rhombus-shaped.

Spindle-shaped calcium carbonate is the most common crystal form of light calcium, with an average long-axis particle size of 5 to 12 μm and an average short-axis particle size of 1 to 3 μm. The average particle size of cubic calcium carbonate is 0.02~0.1μm. The average particle size of needle-shaped calcium carbonate is 0.01 to 0.1 μm, and the average aspect ratio is 5 to 100. The average particle size of chain calcium carbonate is 0.01 to 0.1 μm, and the average aspect ratio is 10 to 50. The average particle size of spherical calcium carbonate is 0.03~0.05μm. The average particle size of flaky calcium carbonate is 1 to 3 μm.

7. Taste

Due to the incomplete reaction of calcium oxide, light calcium has a residual lime taste, which will cause a choking taste when filling biscuits; heavy calcium does not.

8. Particle size

The particle size of heavy calcium products ranges from 0.5 to 45 μm. According to its original average particle size (d), it is divided into: coarsely ground calcium carbonate (d >3μm), finely ground calcium carbonate (d =1~3μm), ultrafine carbonate Calcium (d =0.5~1μm).

According to its original average particle size (d), light calcium can be divided into: micron calcium carbonate (d >5μm), micron powdered calcium carbonate (d =1~5μm), fine calcium carbonate (d =0.1~1μm), ultrafine calcium carbonate (d =0.02~0.1μm), ultrafine calcium carbonate (d<0.02μm).

9. Settlement volume

The sedimentation volume is the volume of unit mass of calcium carbonate after shaking in 100 mL of water and letting it stand for 3 hours.

The larger the sedimentation volume, the smaller the product particle size, the lighter the density, and the higher the product grade.

The sedimentation volume of heavy calcium is 1.1~1.4mL/g.

The settling volume of light calcium is 2.4-2.8mL/g, and the settling volume of nano-light calcium is 3.0-4.0mL/g.

10. Specific volume

The specific surface area of ordinary heavy calcium is generally about 1m2/g, and the specific surface area of heavy fine calcium carbonate is 1.45~2.1m2/g.

The specific surface area of ordinary light calcium is generally about 5m2/g, and the specific surface area of light and fine calcium carbonate is 27~87m2/g.

11. Liquidity

From the perspective of fluidity, the microstructure of light calcium is a spindle shape, and its own oil absorption value is relatively large, which can absorb components in the formula that promote flow such as lubricants, plasticizers, coupling agents, dispersants, etc. Therefore, its fluidity is not as good as heavy calcium. Generally, adding more than 25 parts will seriously affect the fluidity.

The granular form of heavy calcium can promote fluidity, and the amount added is not limited. If more than 25 parts of calcium carbonate are added to the PVC pipe formula, it is best to use heavy calcium from the perspective of fluidity.

12. Price

The processing of heavy calcium is mainly achieved through mechanical crushing and grinding.

The production of light calcium is made through chemical reaction precipitation. The latter process is much more complicated than the former, and the requirements are correspondingly much stricter. Therefore, heavy calcium with the same particle size is about 30% cheaper than light calcium. If the performance allows It is more economical and cheaper to choose heavy calcium.

13. Modification function

Heavy calcium has better tensile strength, and the processing fluidity of heavy calcium plastic is better, and the performance of heavy calcium filled plastic with smaller particle size is also better.

Light calcium has better impact strength and rigidity. Generally, plastics made with light calcium have a smoother surface and lower density.

14. Color and light controllability

Hue is the main hue of a color, while chromatic light is the afterglow of a color. Powders with different crystal forms have different hues. Calcium carbonate has three different crystal forms, so it also has different hues.

For heavy calcium, the background color of calcium carbonate from different origins is different, and it will not change after crushing and refinement. For example, the background color of Sichuan calcium carbonate is blue, the background color of Guangxi calcium carbonate is red, and the background color of Jiangxi calcium carbonate is cyan etc.

As for light calcium, the type of crystal form it produces can be controlled during the synthesis process, and thus the type of color light can be controlled. In the specific color matching, the color of calcium carbonate should be consistent with the color of the main colorant.

15. pH value

Heavy calcium has a pH of 8-9.

The pH value of light calcium is 9-10.

16. Application performance

Heavy calcium: Mainly used in industries such as papermaking, rubber and plastics, the filling amount is generally large, and it is mainly used as a volume filler to reduce the manufacturing cost of applied products.

Light calcium: It has a relatively wide range of application areas. The main application areas are plastics, rubber, coatings, adhesives, cigarette papers, inks, etc., mainly for volume filling, and nano calcium carbonate products are often used as modifications or reinforcements during the application process. When using other functional fillers, the filling amount is generally smaller.

The difference between light calcium and heavy calcium-calcium carbonate Raymond mill HC1500

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