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Yuan lei small class | calcium carbonate, you should know these

Release time:

2024-01-29 09:38

 

Yuan lei small class | calcium carbonate, you should know these

 

Calcium carbonate (CaCO3

It is an important and widely used inorganic salt, which is usually divided into heavy calcium carbonate and light calcium carbonate according to different processing methods.Calcium carbonate, whether heavy calcium carbonate or light calcium carbonate, is the largest and most widely used powder filler in plastics, rubber, paper and other industries.

 

heavy calcium carbonate:Also known as ground calcium carbonate, referred to as heavy calcium, is natural calcite, limestone, dolomite, chalk, shells and other raw materials through physical methods of processing.

 

 

light calcium carbonate:Also known as precipitated calcium carbonate, referred to as light calcium, is processed by chemical methods.

 

 

Calcium carbonate can not only reduce the raw material cost of plastic products, but also improve some properties of plastic materials.The research results show that different types of calcium carbonate can significantly improve the performance of matrix plastics when used properly, but the specific distinction between light calcium and heavy calcium has been plagued by most users. The following author will introduce the differences between the two from 17 different angles.

 

 

No.1

mode of production

 

 

Heavy calcium is mainly based on calcite, marble, limestone, chalk, white marble and other natural minerals as raw materials, the powder material obtained by mechanical grinding; 

 

Light calcium is mainly limestone as raw material, through calcination, digestion, carbonization, dehydration, drying, classification and other processes to obtain the powder material.   

 

 

No.2

Bulk density

 

 

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

 

The bulk density of heavy calcium products is larger, generally 0.8~1.3g/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.

 

No.3

oil absorption value

 

 

Heavy calcium due to large particles, smooth surface, small specific surface area, so the oil absorption value is low, generally 40~60mL/100g;

 

The 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.

 

No.4

Whiteness

 

 

Heavy calcium due to the relative impurities, so the product whiteness is generally 89% ~ 93%, very few products can reach 95%;

 

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

 

 

No.5

Moisture content

 

 

Heavy calcium product moisture is generally 0.2%~ 0.3%, the moisture content is relatively low, but also more stable, some high-grade product moisture can even reach about 0.1%; 

 

Ordinary light calcium products moisture 0.3%~ 0.8%, sometimes there will be some fluctuations, not very stable.

 

No.6

particle shape

 

 

Heavy calcium powder is characterized:The shape of the particles is irregular, and the particles have certain edges and corners, and the surface is rough;The particle size difference is large, the particle size distribution is wide, and the particle size is large.Crushing and refinement will not change the crystal form of heavy calcium. Generally, calcite heavy calcium is hexagonal and marble heavy calcium is cubic, which is mainly related to the origin. 

 

Light calcium powder is characterized:The particle shape is regular and can be regarded as monodisperse powder;The particle size distribution is narrow.According to the different grain shape, light calcium can be divided into spindle, cubic, needle, chain, spherical, flake and rhombus. 

 

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

 

 

No.7

Taste

 

 

Light calcium due to calcium oxide reaction is not complete, residual lime taste, such as filling biscuits will have a choking taste;And heavy calcium does not.

 

No.8

Particle size

 

 

The particle size of heavy calcium products is 0.5 ~ 45μm, which is divided:Coarse ground calcium carbonate (d >3μm), fine ground calcium carbonate (d = 1 ~ 3μm), superfine calcium carbonate (d = 0.5 ~ 1μm);

 

Light calcium according to its original average particle size (d) can be divided:Particulate calcium carbonate (d >5 μm), micro-powder calcium carbonate (d = 1~5 μm), fine calcium carbonate (d = 0.1~1 μm), ultra-fine calcium carbonate (d = 0.02~0.1 μm), ultra-fine calcium carbonate (d <0.02 μm).

 

 

No.9

Sedimentation volume

 

 

The sedimentation volume is the volume that a unit mass of calcium carbonate has after shaking in 100ml of water and standing for 3h.

 

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

 

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

 

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

 

No.10

specific surface area

 

 

The specific surface area of common heavy calcium is generally about 1 m2/g, and the specific surface area of heavy fine calcium carbonate is 1.45-2.1 m2/g;

 

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

 

 

No.11

Liquidity

 

 

Considering from the fluidity, the microstructure of light calcium is spindle-shaped, and its own oil absorption value is relatively large, which can absorb the components that promote flow in the formula such as lubricants, plasticizers, coupling agents, dispersants, etc., so its fluidity is not as good as heavy calcium, and the general addition of more than 25 parts will seriously affect the fluidity;

 

Heavy calcium is granular can promote fluidity, the amount of addition is not limited, in the PVC pipe formula if the calcium carbonate to add more than 25 copies, from the liquidity to consider the best choice of heavy calcium.

 

No.12

Price

 

 

The processing of heavy calcium is mainly realized by mechanical crushing and grinding;

 

The production of light calcium is prepared by chemical reaction precipitation. The latter is much more complicated than the former process and requires much stricter requirements. Therefore, heavy calcium with the same particle size is about 30% cheaper than light calcium. If the performance allows the choice of heavy calcium, it is more economical and cheaper.

 

 

No.13

modified function

 

 

Heavy calcium has better tensile strength, and the fluidity of heavy calcium plastic processing 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, the plastic surface of light calcium is smoother, and the density will be lower.

 

No.14

controllable degree of color light

 

 

Hue is the dominant hue of a color, while color light is the afterglow of a color.The powder of different crystal forms has different hues, and calcium carbonate has three different crystal forms, so it also has different hues.

 

For heavy calcium, the background color of calcium carbonate from different producing areas is different, and the crushing and refinement will not change, such as 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;

 

For light calcium, in the process of synthesis, the type of crystal form can be controlled, and then 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.

 

 

No.15

pH

 

 

The pH value of heavy calcium is 8-9;

Light calcium has a pH of 9-10.

 

No.16

Mineral Economics Contrast

 

 

powder preparation cost:Conventional costs are comparable and at the same competitive level, but if additional environmental control costs and resource waste rates are added, the expansion cost of light calcium is higher than that of heavy calcium; 

 

Environmental balance:Heavy calcium production in addition to noise, no "three wastes" emissions, environmental coordination and control;Light calcium production emissions "three wastes", especially combustion exhaust gas, the total environmental balance is low;

 

Resource Utilization:Heavy calcium is easy to comprehensive utilization of mineral resources, light calcium is not easy to control the rational utilization of mineral resources.

 

No.17

Application Performance

 

 

 

Heavy Calcium:Mainly used in papermaking, rubber and plastics industries, the filling amount is generally large, mainly as a volume filler, reducing the manufacturing cost of application products;

 

Light calcium:The main application areas are plastics, rubber, coatings, adhesives, cigarette paper, inks, etc., which are mainly filled with volume, while nano calcium carbonate products are often used as functional fillers such as modification or reinforcement in the application process, and the filling amount is generally less.

 

 

Conclusion:Correctly distinguish between light calcium and heavy calcium, in the specific formula design to choose their own calcium carbonate is of great significance, so that you can select materials as needed, both to meet the performance and reduce costs.

 

 

 

 

 

 

 

Calcium carbonate, product, particle size, general, average, different, plastic, granule, fluidity

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