Limestone is a common non-metallic mineral and a valuable resource with a wide range of uses. Limestone is a trade name that uses limestone as a mineral raw material. Limestone has been widely used in the history of human civilization because of its wide distribution and easy accessibility in nature.
In modern Industry, limestone is the main raw material for the manufacture of cement, lime and calcium carbide. It is an indispensable flux limestone in the metallurgical Industry. After superfine grinding, high-quality limestone is widely used in papermaking, rubber, paint, coatings, and medicine. , Cosmetics, feed, sealing, bonding, polishing and other products. According to incomplete statistics, the total ratio of limestone and building stones consumed in cement production, lime production, metallurgical flux, and limestone consumed by ultrafine calcium carbonate is 1:3.
1. Name: Limestone, Limestone.
2. Composition: Limestone is a collection of minerals, the main mineral is calcite, followed by dolomite, magnesite and other carbonate minerals, in addition to chalcedony, clay, pyrite, marcasite, water needle Minerals such as iron ore, sea green stone, organic carbon, asphalt, gypsum, anhydrite and phosphate.
3. Physical properties: Limestone is presented as calcite crystallites, with complex crystal shapes, often in the form of partial triangles and rhombohedrons, light gray or blue gray compact blocks, granules, nodules and porous structures. Hardness 3; Density: 2.6-2.9; Melting point is 825°C; Decomposes into calcium oxide and carbon dioxide between 830°C and 1020°C; it boils and dissolves in dilute acid.
7,000 to 8,000 cement limestone mines have been discovered nationwide, of which 1,286 have proven reserves, including 257 large-scale deposits, 481 medium-sized deposits, and 486 small-scale deposits. (Ore reserves greater than 80 million tons are large-scale, 4,000-8,000 Ten thousand tons are medium-sized, and less than 40 million tons are small-sized), with a total of 54.2 billion tons of ore reserves, of which limestone reserves are 50.4 billion tons, accounting for 93%; marble reserves are 3.8 billion tons, accounting for 7%. The reserves are widely distributed in 29 provinces, municipalities and autonomous regions except Shanghai. Among them, Shaanxi Province has reserves of 4.9 billion tons, which is the highest in the country; the rest are Anhui Province, Guangxi Autonomous Region, and Sichuan (including Chongqing) provinces. Reserves of 3.4 to 3 billion tons; Shandong, Hebei, Henan, Guangdong, Liaoning, Hunan, and Hubei each have reserves of 3 to 2 billion tons; Heilongjiang, Zhejiang, Jiangsu, Guizhou, Jiangxi, Yunnan, Fujian, Shanxi, Xinjiang, Jilin , Inner Mongolia, Qinghai, and Gansu provinces each have reserves of 2 to 1 billion tons; Beijing, Ningxia, Hainan, Tibet, and Tianjin each have reserves of 500 to 200 million tons.
1. Cement Industry
Limestone is the main raw material of cement, accounting for 70% to 90% of the raw material composition. The ingredients are clay raw materials, siliceous raw materials, and iron-aluminum raw materials. The use of limestone processing to make machine-made sand can effectively increase the yield of limestone lump ore, reduce the amount of limestone waste slag discharged, and the effect of energy saving and emission reduction is obvious.
2. Glass Industry
Limestone is an important raw material in the production of flat glass. It mainly introduces calcium oxide into the glass to increase the chemical stability and mechanical strength of the glass. The quality of limestone raw materials has a great influence on the melting of glass.
3. Ceramic Industry
In ceramic tiles, the amount of limestone used is between 5-15%. In the ceramic blank glaze, it mainly plays the role of flux. Used in the glaze, it can increase the hardness and wear resistance of the glaze; increase the corrosion resistance of the glaze; reduce the high temperature viscosity of the glaze and increase the gloss of the glaze. Carbonate flux raw materials are widely used in building and sanitary ceramic products.
4. Plastic Industry
Calcium carbonate is the most widely used and most used inorganic mineral powder material. As a commonly used powder material for plastics, calcium carbonate has many advantages that other powder materials do not have, such as high whiteness, easy surface organic treatment, and processing The equipment and molds have light abrasion, good molding processing fluidity, etc., combined with abundant resources and low prices, it has become the first choice for inorganic mineral powder materials in the plastics processing Industry.
5. Rubber Industry
For rubber, calcium carbonate is the third largest reinforcing filler after carbon black and white carbon black. It has the characteristics of low toxicity, low price, and good reinforcing effect.
6. Paint Industry
Heavy calcium carbonate is the first filler in the coating Industry in the world. It is not only cheap, but also can greatly reduce the production cost of coatings. As one of the functional fillers, it can affect many properties of the coating, such as changing the mechanical strength of the coating. Improve the water resistance and chalking resistance of the coating film. Because it is a high-quality and inexpensive functional filler, calcium carbonate has always been one of the most important basic substances in the composition of coatings in civil and industrial coatings.
7. Paper Industry
Calcium carbonate is one of the main inorganic chemical raw materials in the paper Industry. The calcium carbonate used as paper filler and paper coating pigment can be classified into two categories: one is natural calcium carbonate (GL) made from ground limestone, and the other is chemical A synthetic product made by precipitation-precipitated calcium carbonate (PCC). The purpose of adding fillers in papermaking is to increase the opacity and brightness of the paper, improve the smoothness and uniformity of the paper, increase the softness of the paper, and reduce the moisture absorption and deformation of the paper. For printing paper, the ink absorption and printability of the paper are enhanced after filling. Adding fillers to a larger extent is also beneficial to reduce paper costs.
8. Food Industry
Pure mineral calcium carbonate, various harmful substances in minerals, such as heavy metal ions, have been removed by various processes, and prepared into relatively pure calcium carbonate, which is used as an additive for various foods. Calcium carbonate can be used as additives, supplements, curing agents, anti-caking agents, yeast sugar additives, calcium supplements and modifiers in foods. Some foods are darker or darker in color, resulting in unsatisfactory visual effects. When required, calcium carbonate is added to whiten, increase the visual effect, and meet the needs of consumers; calcium carbonate can also be used as a leavening agent and starter in some foods to reduce the fermentation time.
9. Pharmaceutical Industry
In the prevention and treatment of osteoporosis and other related diseases, calcium carbonate is the most widely used because of its high calcium content, low price, no side effects, and the best effect-price ratio. Although there are more than a dozen calcium salts as calcium supplements, calcium carbonate preparations are the best calcium supplements that are most widely used, contain the highest calcium content, have good effects, and are low in price.
10. Other Industries
Calcium carbonate can be used as a friction agent in toothpaste and an additive in animal feed; calcium carbonate is also used in printing inks, putties, sealing waxes, and adhesives, mostly to increase volume and reduce costs.