The difference between heavy calcium carbonate and light calcium carbonate!

The difference between heavy calcium carbonate and light calcium carbonate!

Calcium carbonate can not only reduce the cost of raw materials for plastic products, but also has the effect of improving some properties of plastic materials. Research results show that different types of calcium carbonate can significantly improve the performance of matrix plastics when used, but the specific distinction between light calcium carbonate and heavy calcium carbonate has been plaguing most users, and Shanghai Chuangyu Chemical New Materials Co., Ltd. will introduce the difference between the two from 17 different angles.

First, the main ingredients

Heavy calcium carbonate is mainly based on calcite, marble, limestone, chalk, white jade and other natural minerals as raw materials, through mechanical grinding processing of powder materials;

Lightweight calcium carbonate is mainly a powder material obtained by calcination, digestion, carbonization, dehydration, drying, grading and other processes using limestone as raw material.

Second, product bulk density

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

The bulk density of heavy calcium carbonate products is large, generally 0.8~1.3g/cm3;

The bulk density of light calcium carbonate 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.

Third, the oil absorption value

Due to the large particles, smooth surface and small specific surface area, the heavy calcium carbonate has a low oil absorption value, generally about 40-60mL/100g;

Lightweight calcium carbonate particles are fine, the surface is rough, the specific surface area is large, so the oil absorption value is high, generally about 60-90mL/100g.

Fourth, whiteness

Due to the relative number of impurities in heavy calcium carbonate, the whiteness of products is generally 89% to 93%, and very few products can reach 95%;

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

Fifth, moisture content

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

Ordinary lightweight calcium carbonate products have a moisture content of 0.3% to 0.8%, sometimes with certain fluctuations and are not very stable.

Sixth, powder characteristics

The powder characteristics of heavy calcium carbonate are: the particle shape is irregular, and the particles have certain edges and angles, 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 refinement will not change the crystal form of heavy calcium carbonate, generally calcite heavy calcium carbonate is hexagonal crystalline, marble heavy calcium carbonate is cubic crystal form, mainly related to the place of origin.

The powder of light calcium carbonate is characterized by a regular particle shape and can be regarded as a monodisperse powder, and a narrow particle size distribution. According to the shape of the grain, lightweight calcium carbonate can be divided into spindle shape, cubic, needle, chain, spherical, flake and diamond shape.

Seven, particle size

Spindle-shaped calcium carbonate is the most common crystal shape in light calcium carbonate, with an average major shaft particle size of 5-12 μm and an average short shaft particle size of 1-3 μm;

The average particle size of needle-shaped calcium carbonate is 0.01-0.1 μm, and the average length-to-diameter ratio is 5-100;

The average particle size of chain calcium carbonate is 0.01-0.1 μm, and the average length-to-diameter ratio is 10-50;

The average particle size of spherical calcium carbonate is 0.03-0.05 μm;

The average particle size of cubic calcium carbonate is 0.02-0.1 μm;

The average particle size of flake calcium carbonate is 1-3 μm.

Light calcium carbonate due to the incomplete calcium oxide reaction, residual lime flavor, such as filled biscuits will have a choking taste, while heavy calcium carbonate does not.

The particle size of heavy calcium carbonate products ranges from 0.5 to 45 μm, and is divided into crudely ground calcium carbonate (>3 μm), finely ground calcium carbonate (1-3 μm), ultrafine calcium carbonate (0.5-1 μm) according to its original average particle size (d);

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

Sedimentation volume

The sedimentation volume is the volume of calcium carbonate per unit mass after oscillation in 100mL of water and standing for 3h.

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

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

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

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

liquidity

From the perspective of fluidity, the microstructure of lightweight calcium carbonate is spindle shape, coupled with its own oil absorption value is relatively large, the components that promote flow in the formula such as lubricants, plasticizers, coupling agents, dispersants, etc. can be absorbed, so its fluidity is not as good as heavy calcium carbonate, and the general addition of more than 25 parts will seriously affect the fluidity;

Heavy calcium carbonate for granular can promote fluidity, the amount of addition is not limited, in the PVC pipe formula if the calcium carbonate added more than 25 parts, if from the flow of the consideration of the best choice of heavy calcium carbonate.

Processing technology

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

The production of light calcium carbonate is prepared by precipitating through chemical reactions, the latter is much more complex than the former process, the requirements are correspondingly more stringent, so the same particle size of heavy calcium carbonate is about 30% cheaper than light calcium carbonate, if the performance allows the choice of heavy calcium carbonate is more economical and cheaper.

Tensile strength

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

Lightweight calcium carbonate has a good impact strength and rigidity, and the surface of the plastic with light calcium is generally smoother, and the density will be lower.

Hue

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

For heavy calcium carbonate, the background color of calcium carbonate from different origins is different, and the crushing and refinement will not change, such as the blue color of Sichuan calcium carbonate, the red color of Guangxi calcium carbonate, the blue color of Jiangxi calcium carbonate and so on;

For lightweight calcium carbonate, because it is artificially made by chemical synthesis, the type of crystal form it produces in the process of synthesis can be controlled, and all of them can control the type of color and light. In the specific color matching, the color light of calcium carbonate should be consistent with the hue of the main colorant.

Ph value

The pH of heavy calcium carbonate is 8-9;

Lightweight calcium carbonate has a pH of 9-10.

Preparation costs

Powder preparation cost: the conventional cost is comparable, at the same level of competition, but if the additional environmental control cost and resource waste rate, the light calcium carbonate expansion cost is higher than that of heavy calcium carbonate;

Environmental balance

Environmental balance: in addition to noise, there is no "three wastes" emissions in heavy calcium carbonate production, and the environment is easy to coordinate and control; the production and emission of light calcium carbonate emissions "three wastes", especially combustion waste gas, the total environmental balance is low;

Resource utilization

Resource utilization rate: Heavy calcium carbonate is easy to comprehensive utilization of mineral resources, and light calcium carbonate is not easy to control the reasonable utilization rate of mineral resources by virtue of chemical processing capacity.

Scope of application

Heavy calcium carbonate products: mainly used in papermaking, rubber and plastics and other industries, the filling volume is generally large, mainly as a volume filler, reducing the manufacturing cost of applied products;

Lightweight calcium carbonate products: relative application areas are more extensive, the main application areas are plastics, rubber, coatings, adhesives, cigarette paper, inks, etc., mainly volume filling, while nano calcium carbonate products are often used as modified or reinforced functional fillers in the application process, and the filling amount is generally less.