Heavy calcium carbonate, referred to as heavy calcium, is made from ground natural carbonate minerals such as calcite, marble, and limestone. It is a commonly used powdery inorganic filler with high chemical purity, high inertness, not easy to react chemically, good thermal stability, will not decompose below 400°C, high whiteness, low oil absorption, low refractive index, soft, dry, It does not contain crystal water, has low hardness and low wear value, is non-toxic, tasteless, odorless, and has good dispersibility.     Physical and chemical properties   The chemical formula of calcium carbonate is CaCO3. Its crystals mainly include trihedral calcite and orthorhombic aragonite. At normal temperatures and pressures, calcite is stable and aragonite is quasi-stable. Currently, calcite is the main form. Lord.   Under normal pressure, when calcite is heated to 898°C and aragonite is heated to 825°C, it will decompose into calcium oxide and carbon dioxide; calcium carbonate reacts with all strong acids to generate water and corresponding calcium salts (such as calcium chloride CaCl2). At the same time, carbon dioxide is released; at normal temperature (25 ℃), the concentration product of calcium carbonate in water is 2.8E-9, the solubility is 0. 0014, the pH value of calcium carbonate aqueous solution is 9. 5~10. 2, and air-saturated calcium carbonate The pH value of the aqueous solution is 8. 0~8. 6. Calcium carbonate is non-toxic, odorless and non-irritating. It is usually white and has a relative density of 2. 7~2. 9. The Mohs hardness scale is 3 for calcite and 3.5~4 for aragonite. Calcite has three sets of rhombohedral complete cleavages, and aragonite also has cleavage. The sedimentation volume of heavy calcium carbonate: 1. 2~1. 9ml/g, and the specific surface area is about 1m2/g; due to its large particles, smooth surface, and small specific surface area, heavy calcium carbonate has a low oil absorption value of 48ml/ About 100g.   Heavy calcium carbonate is stable in air. Almost insoluble in water and insoluble in alcohol. It will boil and dissolve when encountering dilute acetic acid, dilute hydrochloric acid and dilute nitric acid. When heated to 898°C, it begins to decompose into calcium oxide and carbon dioxide.   production method   There are two production processes for heavy calcium carbonate. Dry production process: first hand-select calcite, limestone, chalk, shells, etc. transported from the quarry to remove gangue; then use a crusher to coarsely crush the limestone, and then use a Raymond (pendulum) mill to crush it Fine limestone powder is obtained, and finally the powder is graded using a classifier. The powder that meets the particle size requirements is packaged and stored in the warehouse, otherwise it is returned to the mill for grinding again. Wet production process: First, dry fine powder is made into a suspension and placed in a mill for further crushing. After dehydration and drying, ultra-fine heavy calcium carbonate is obtained.   particle shape   The shape of heavy calcium carbonate is irregular, its particle size varies greatly, and the particles have certain edges and corners, the surface is rough, the particle size distribution is wide, the particle size is large, and the average particle size is generally 1~10 μm. Heavy calcium carbonate is divided into: coarsely ground calcium carbonate (> 3μm), finely ground calcium carbonate (1~3μm), ultrafine calcium carbonate (0.5~1μm heavy calcium carbonate) according to its original average particle size (d) Powder characteristics: a. Irregular particle shape; b. Broad particle size distribution; c. Large particle size.   Application areas   1. Heavy calcium powder for rubber industry Rubber-Heavy calcium carbonate powder for rubber: 400 mesh, whiteness: 93%, calcium carbonate: 96%) Calcium carbonate is one of the largest fillers used in the rubber industry. Calcium carbonate is filled in large amounts in rubber, which can increase the volume of its products and save expensive natural rubber, thus greatly reducing costs. Calcium carbonate filled in rubber can obtain higher tensile strength and tear resistance than pure rubber vulcanization. cracking strength and wear resistance.   2. Heavy calcium powder plastics used in the plastics industry – heavy calcium carbonate powder (heavy calcium powder) 400 mesh for plastic masterbatch and color masterbatch. It is required that the whiteness remains unchanged after high temperature heating. The ore structure is large crystalline calcite, and the calcium carbonate content :99%, whiteness: 95%), calcium carbonate can play a skeleton role in plastic products, which plays a great role in the dimensional stability of plastic products. It can also increase the hardness of the products and improve the surface gloss of the products. And surface smoothness. Since the whiteness of calcium carbonate is above 90, it can also replace expensive white pigments.   3. Heavy calcium powder paint used in the paint industry – heavy calcium carbonate (heavy calcium powder) used in latex paint 800 mesh or 1000 mesh, whiteness: 95%, calcium carbonate: 96%) The amount of calcium carbonate used in the paint industry is also relatively large Large, for example, the dosage is more than 30% in thick paint.   4. Heavy calcium powder used in water-based coating industry. Heavy calcium carbonate (heavy calcium powder) used in water-based coating industry is 800 mesh or 1000 mesh, whiteness: 95%, calcium carbonate: 96%.) Calcium carbonate has more uses in the water-based coating industry. It is widely used and can make the coating non-settling, easy to disperse, and has good gloss. The dosage in water-based coatings is 20-60%.   5. Heavy calcium carbonate (heavy calcium powder) used in papermaking industry: 325 mesh, whiteness requirement: 95%, calcium carbonate content: 98% Calcium carbonate plays an important role in the papermaking industry. It can ensure the strength of paper and whiteness, and lower cost.   6. Heavy calcium powder used in the construction industry (dry mortar, concrete). Heavy calcium carbonate (heavy calcium powder) used in dry mortar 325 mesh, whiteness requirement: 95%, calcium carbonate content: 98%) Calcium carbonate in the construction industry It plays an important role in concrete. It can not only reduce production costs, but also increase the toughness and strength of the product.   7. Heavy calcium powder for fireproof ceiling industry: Heavy calcium carbonate (heavy calcium powder) for fireproof ceilings: 600 mesh, whiteness requirement: 95%, calcium carbonate content: 98.5%) Calcium carbonate needs to be used in the production process of fireproof ceilings. It can improve the whiteness and brightness of the product, and the fire resistance will also be increased.   8. Heavy calcium carbonate for artificial marble industry (heavy calcium carbonate for artificial marble (heavy calcium powder): 325 mesh, whiteness requirement: 95%, calcium carbonate content: 98.5%, pure and without impurities) Calcium carbonate has been widely used in Artificial marble production.   9. Heavy calcium powder used in the floor tile industry. Heavy calcium carbonate (heavy calcium powder) for floor tiles: 400 mesh, whiteness requirement: 95%, calcium carbonate content: 98.5%, pure and without impurities) Calcium carbonate can be used in floor tiles Industry, used to increase the whiteness and tensile strength of products, improve the toughness of products, and reduce production costs.