Heavy calcium carbonate is a powdery material made from natural minerals such as calcite, marble, limestone, chalk, and Hanbaiyu through mechanical grinding and processing. It is an important industrial filler, pigment, and chemical product. A comprehensive understanding of the application fields and requirements of calcium carbonate will help enterprises to plan products and develop technologies. Below, Guangxi Longhua New Materials will share with you the nine major application fields of heavy calcium carbonate!

Precipitated calcium carbonate is a powdery material made from natural minerals such as calcite, marble, limestone, chalk, and white marble through mechanical grinding and processing. It is an important industrial filler, pigment, and chemical product. A comprehensive understanding of the application fields and requirements of calcium carbonate will help companies to plan their products and conduct technological development. Below, Guangxi Longhua New Materials will share with you the nine major application areas of precipitated calcium carbonate!

　1. Papermaking

　For the papermaking industry, precipitated calcium carbonate is the second most important raw material after fiber. As a filler and coating pigment, precipitated calcium carbonate mainly improves the properties of paper in the following aspects:

　(1) Improve opacity and brightness;

　(2) Improve smoothness, uniformity, and softness;

　(3) Reduce hygroscopicity and deformation;

　(4) Enhance ink absorbency and printability;

　(5) Reduce paper costs.

　Practice has shown that the lower the abrasion value of precipitated calcium carbonate, the more beneficial it is to protect and extend the life of the filter screens, cutter heads, and other parts of the paper machine. Therefore, developed countries such as Europe generally choose high-purity, high-whiteness high-quality chalk as the preferred raw material for precipitated calcium carbonate used in papermaking. When marble and calcite are used as raw materials for precipitated calcium carbonate in papermaking, the purer the ore and the higher the calcium carbonate content, the more beneficial it is to papermaking.

　2. Plastics

　The plastics industry is the largest consumer of calcium carbonate in China. Calcium carbonate is widely used in filling polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), acrylonitrile butadiene-styrene copolymer (ABS), etc. Its main functions are:

　(1) Improve the dimensional stability of plastic products;

　(2) Improve the hardness and rigidity of plastic products;

　(3) Improve the processing performance of plastics;

　(4) Improve the heat resistance of plastic products;

　(5) Improve the light scattering of plastics;

　(6) Provide functionality, such as insulation and flame retardancy.

　(7) Reduce the cost of plastic products.

　

　3. Coatings

　Calcium carbonate is the most widely used extender pigment in coatings, acting as a skeleton and filling material in the paint film, while improving the coating performance.

　(1) In putty powder, 70-80% is heavy calcium;

　(2) In thick paint, the amount of calcium carbonate is generally over 30%; in water-based coatings, the amount of calcium carbonate is 20-60%;

　(3) In topcoats, calcium carbonate is an ideal matting filler, such as matte white casein glue wall paint containing 11.5% precipitated calcium carbonate;

　(4) In metal anti-rust coatings, calcium carbonate has a certain anti-rust effect, with an appropriate amount of about 30%;

　(5) In interior decorative paints, such as polyvinyl acetate emulsion paints, usually contain about 10% calcium carbonate.

　For example, ultra-fine precipitated calcium carbonate powder materials have significant effects on shortening the dispersion and grinding time in the production of emulsion paints, improving the hiding power, improving the viscosity of the emulsion, reducing the amount of titanium dioxide, and improving the grinding performance of putty.

　When designing coating formulations, high-performance emulsion paints use ultra-fine calcium carbonate, while low-grade emulsion paints choose relatively coarse particles and low oil absorption heavy calcium.

　Currently, the precipitated calcium carbonate powder with better application effect in interior wall emulsion paints has a particle size control of d97 < 10μm, d50 of about 1.5μm, whiteness > 95%, and CaCO3 ≥ 98%.

　4. Rubber

　Precipitated calcium carbonate is mainly used as a filler in the rubber industry, and can also be used with other reinforcing agents to improve the processing properties of the rubber and the performance of the products. It is suitable for shoe heels, soles, floors, rubber tubes, and molded, extruded, and foamed rubber products.

　(1) Increasing volume and capacity;

　(2) Improve the stiffness of the rubber;

　(3) Improve electrical insulation;

　(4) Reduce the extrusion shrinkage rate of the rubber;

　(5) Reduce the production cost of products;

　(6) It can also be used as a release agent, mold release agent, or white pigment.

　

　5. Breathable membrane

　Breathable membranes are made by adding about 50% special calcium carbonate to a PE or PP carrier, blending, extruding into a film, and then uniaxially stretching to a certain magnification. They are widely used in medical and hygiene product packaging (such as medicinal films, surgical gowns, medical gloves, sanitary napkins, baby diapers, disposable bed sheets, and other clinical medical consumables), food packaging (such as fresh-keeping films, composite films, cooked food packaging bags), and daily necessities (such as warm clothing interlayers, disposable lightweight raincoats), etc.

　There are two key factors in the production of breathable membranes: one is calcium carbonate, and the other is stretching. The performance indicators of calcium carbonate directly affect the processability of the breathable membrane (such as coking time, extrusion stability, manufacturability of thin films, and pinhole defects) and physical properties (such as air permeability, water resistance, thermal stability, and mechanical properties).

　 

　6. Food

　In the food industry, heavy calcium carbonate can be used as an alkaline agent, nutritional supplement, dough conditioner, solidifying agent, yeast nutrient, anti-caking agent, loosening agent, chewing gum aid, and modifier, etc. It can also be added to calcium-enriched health foods, chewing gum base, leavening agents, noodles, breakfast cereals, biscuits, dairy products, soft capsules, and even high-purity pharmaceutical-grade calcium citrate, calcium lactate, calcium citrate-malate, and calcium gluconate, which are ideal reaction raw materials for organic calcium salts.

　Regarding calcite raw materials, the raw ore used to produce food-grade calcium carbonate must be high-quality, high-content, pure natural ore. No pollution or impurities are allowed during processing, and the packaging process must also ensure cleanliness and no pollution.

　

　7. Toothpaste

　In the toothpaste industry, calcium carbonate is a commonly used abrasive, inexpensive, and readily available raw material (using limestone or calcite as raw materials), widely used in mid-to-low-end toothpastes.

　The shape, size, hardness, and content of the abrasive in toothpaste are the main factors determining the abrasiveness of the toothpaste. Abrasive particles should have appropriate hardness, uniform fineness, low solubility, chemical stability, white appearance, no odor, comfortable taste, and be completely non-toxic.

　

　8. Feed

　Heavy calcium carbonate is a feed-type mineral raw material used as a calcium source for calcium supplementation. The general amount added to feed is 0.5-1%. Chickens, ducks, and geese that lay eggs need to add an appropriate amount of calcium carbonate to their feed. During the peak egg-laying period, the amount can be increased to 8-9%.

　For heavy calcium carbonate used in feed, particle size is an important quality indicator. For example, heavy calcium carbonate for laying hens should not be pulverized too finely, because small calcium particles have a short residence time in the gizzard and low utilization rate, leading to a decrease in eggshell quality. Studies have shown that when heavy calcium carbonate is used in a mixture of different particle sizes (i.e., 75% 6-8 mesh, 12.5% 10-12 mesh, and 12.5% 50 mesh), the egg breakage rate is the lowest, and the eggshell strength is the highest, because the use of a mixture of different particle sizes can provide calcium evenly, thus ensuring the quality of the eggshell. At the same time, the larger particles have a grinding effect similar to sand in the gizzard, which can promote feed digestion.

　

　9. Artificial Stone

　Heavy calcium carbonate powder is the main filler for resin-based artificial stone, generally accounting for more than 75% of the mass of artificial stone. The larger the filling amount, the less resin is used, the lower the production cost, and the more environmentally friendly it is.

　Therefore, as low an oil absorption value as possible is one of the most important technical requirements for heavy calcium carbonate in artificial stone, which often needs to be achieved through surface modification. In addition, higher whiteness is naturally better for white products.

　Currently, the whiteness of heavy calcium carbonate for artificial stone on the market has reached more than 95, and the particle size has various specifications from 20 mesh to 1250 mesh.

　

　In addition, heavy calcium carbonate can also be used in medicine (pH buffer for microbial fermentation, calcium supplement, antacid), construction (dry-mixed mortar, concrete), fertilizers (soil amendment for acid washing), glass (lowering melting point), and flue gas desulfurization.