(difference: limestone is a mixture; Calcium carbonate is a compound)
Chinese name: limestone mbth: classification of calcium carbonate: chemical formula: CaCO3 main components: calcium carbonate belongs to: physical and chemical properties, chemical properties, composition, uses, causes, classification, classification by production methods, classification by powder particle size, classification by microscopic arrangement, hazards, distribution and physical and chemical properties Chinese name: limestone calcium carbonate (calcium carbonate) inchi =1/ch2o3. /h(H2,2,3,4); /q; +2/p-2 Upstream raw materials: diesel oil and explosives. Downstream products: calcium hydroxide, aluminum hydroxide, caustic soda, soda ash, sodium bicarbonate, calcium sulfate, calcium nitrite, calcium chloride, calcium hydrogen phosphate calcium carbonate Density: 2.93g∕cm3 Melting point: 825℃ Water solubility: insoluble in water, soluble in water containing ammonium salt or iron oxide, insoluble in alcohol. Safety data: dangerous goods mark Xi, danger category code R36/38, safety description: S26S37/39 Status: white powder. Odorless and tasteless. Exposure to air, no reaction, insoluble in alcohol. Properties: Boil and dissolve in dilute acetic acid, dilute hydrochloric acid and dilute nitric acid. It decomposes into calcium oxide and carbon dioxide at high temperature. Physical Properties Calcium carbonate is a compound with chemical formula CaCO 3. Si Nuo. 47 1-34- 1. It is a common substance on earth and can be found in rocks. The main components of animal back shells and snail shells. It exists in the form of calcite and aragonite in nature. Calcite is a cubic system with hexagonal crystals. Pure calcite is colorless and transparent, generally white, containing 56% Cao and 44% CO2, with a density of 2.7 15g/cm 3 and a Mohs hardness of 3, showing brittleness. Aragonite belongs to orthorhombic system, rhombic crystal, gray or white, with density of 2.94g/cm 3, Mohs hardness of 3.5-4 and dense nature. The crystal size of calcite is very important in the physical properties of limestone. Dense limestone presents a fine-grained crystal structure with low porosity and high strength. The density of limestone is about 2.65 ~ 2.80g/cm3, dolomite limestone is 2.70 ~ 2.90g/cm3 and dolomite is 2.85 ~ 2.95g/cm3. Bulk density depends on porosity. Thermal expansion of massive calcium carbonate limestone: It shows that the average thermal expansion coefficient of microcrystalline limestone is (4.5 ~ 5.0) * 10 (-6)/℃, while the coarse grain increases to 10. 1 * 10 (-). The heating experiment of limestone is of great significance in lime production. At 800℃ below the decomposition point of limestone, limestone crystals expand, and cracks will form in limestone with high crystallinity, while those larger crystals will break into powder when heated, which is more serious for limestone with good crystal development and much denser calcite. Chemical Properties Calcium carbonate is the main component of limestone, which is decomposed into calcium oxide and carbon dioxide at a higher temperature, in addition to the following chemical properties. L) Chemical resistance Except for acid, many aggressive substances can't attack limestone or can only attack limestone slowly. 2) Acid-resistant limestone reacts with all strong acids to generate calcium salts and release carbon dioxide. The reaction rate depends on the impurities contained in limestone and its crystal size. The higher the impurity content, the larger the crystal and the slower the reaction speed. The reaction speed of dolomite is slower than that of limestone. Judgment method of dolomite and limestone: Drop 10% hydrochloric acid on dolomite to produce a small amount of bubbles, and drop on limestone to produce violent odorless bubbles, and the generated gas can make clear limewater turbid. 3) The reaction of chlorine resistant to various gases and hydrogen chloride with CaCO3 is extremely slow in dry bath and room temperature, and CaCl _ 2 does not accelerate until 600℃; Sulfur dioxide has no significant effect on CaCO3 at room temperature, whether it is gaseous or liquid. While nitrogen dioxide (NO2) reacts with CaCO3 at 65438 05℃ to generate Ca(NO3)2, NO and CO2. Component content: silica 0.07- 1%, alumina 0.02- 1%, iron oxide 0.03- 1%, calcium oxide 48-55.22%, magnesium oxide 0.08- 1%. Block/powder limestone: loss on ignition 40.79%, silicon 4.62%, aluminum 1.2 1%, iron 0.52%, calcium 50. 16%, magnesium1. Dolomite powder/block: silicon 0. 19%, aluminum 0. 15%, iron 0. 17%, calcium 32. 1%, magnesium 21.19. Calcium carbonate used in limestone is the main component of limestone, and limestone is the main raw material for producing glass. Lime and limestone are widely used as building materials and important raw materials for many industries. Calcium carbonate can be directly processed into stone and burned into quicklime. Lime includes quicklime and hydrated lime. The main component of quicklime is CaO, which is generally massive, pure white, and light gray or light yellow when containing impurities. After absorbing water or adding water, quicklime becomes hydrated lime, also called hydrated lime, and its main component is Ca(OH) 2. Slaked lime is mixed into lime slurry, lime paste, lime mortar, etc. , used as coating and tile adhesive. Cement is made by mixing limestone and clay and calcining at high temperature. Glass is made by mixing limestone, quartz sand and soda ash (sodium carbonate) and melting at high temperature. Limestone is used as a flux to remove gangue in ironmaking. Quicklime is used as slagging material in steelmaking to remove harmful impurities such as sulfur and phosphorus. Calcium carbide (mainly CaC 2) is made by the reaction of quicklime and coke in electric furnace. Soda soda is made from limestone, salt, ammonia and other raw materials through multi-step reaction (Solway method). Caustic soda is made by the reaction of hydrated lime and soda ash (causticization method). Bleached lime is prepared by the reaction of pure lime and chlorine. Calcium chloride, calcium nitrate, calcium sulfite and other important calcium salts are made by chemical processing of limestone. Hydrated lime can remove the temporary hardness of water and be used as a hard water softener. Limestone is calcined into pure powdered calcium carbonate, which is used as filler for rubber, plastic, paper, toothpaste, cosmetics and so on. Alkaline lime made of lime and caustic soda is used as an absorbent of carbon dioxide. Quicklime is used as a desiccant and disinfectant. In agriculture, quicklime is used to prepare pesticides, such as lime-sulfur mixture and Bordeaux mixture. The application of hydrated lime in soil can neutralize the acidity of soil, improve soil structure and provide calcium for plants. Brush lime slurry on the trunk to protect the trees. Natural calcium carbonate fly powder: used to produce anhydrous calcium chloride, which is an auxiliary raw material for the production of sodium dichromate. The main raw materials for glass and cement production. In addition, it is also used in building materials and poultry feed. Shuangfei powder: raw materials for producing anhydrous calcium chloride and glass, white fillers for rubber and paint, and building materials. Sanfei powder: used as filler for plastics, paint putty, coating, plywood and paint. Sifei powder: used as filler for wire insulation, rubber molding products and asphalt felt. Calcium carbonate is an important building material. White pure calcium carbonate rock is called white marble, which can be directly used as decorative stone pillars or handicrafts; Calcium carbonate with beautiful patterns due to impurities is called marble, which is used to cover the internal and external walls of buildings or pave the ground; Dense calcium carbonate rock (limestone) can also be directly used in buildings, but the main purpose of limestone is to produce cement. White stone containing more than 90% CaCO3 is crushed, classified and separated by raymond mill or other high-pressure mills to obtain finished products. Genetic limestone is mainly formed in shallow sea environment. Limestone can be divided into granular limestone (deposited by running water) according to its genesis; Bioskeleton limestone and chemical and biochemical limestone. According to the structural structure, it can be subdivided into bamboo limestone, limestone and massive limestone. The main chemical composition of limestone is soluble calcium carbonate, so many stone forests and caves have been formed in limestone areas, which is called karst topography. Limestone generally contains some dolomite and clay minerals. When the content of clay minerals reaches 25%~50%, it is called argillaceous rock. When the content of dolomite reaches 25%~50%, it is called dolomite limestone. Limestone is widely distributed, with uniform lithology and easy to be mined and processed. It is a widely used building material. The main component of limestone is calcium carbonate, which is soluble in water containing carbon dioxide. Generally speaking, a liter of water containing carbon dioxide can dissolve about 50 mg of calcium carbonate. According to a survey conducted by geologists in Guilin, the water there can dissolve and erode the limestone surface as thin as nails every year. Although there is only a little dissolution every year, the development history of the earth is extremely long. In the recent geological period-Quaternary, it was about 3 million years. Even with such a slow dissolution rate, it can dissolve 900 meters in 3 million years! The lone peak in Guilin is only one or two hundred meters high, and the highest in ordinary caves is tens of meters. However, not all places with limestone can form this landform, but limestone with large area, large thickness and pure geology, as well as warm and humid climate conditions, can develop such a perfect landform and form such beautiful natural scenery. According to different production methods, calcium carbonate can be divided into heavy calcium carbonate, light calcium carbonate, colloidal calcium carbonate and crystalline calcium carbonate. Heavy calcium carbonate Heavy calcium carbonate (commonly known as heavy calcium carbonate, single fly powder, double fly powder, three fly powder and four fly powder), whose molecular formula is CaCO _ 3 molecular weight 100.09, can be directly crushed into natural calcite, limestone, chalk and shells. By mechanical means (using raymond mill or other high-pressure mill). Heavy calcium carbonate is called heavy calcium carbonate because its sedimentation volume is smaller than that of light calcium carbonate. Description: White powder. Odorless and tasteless. Exposure to air did not change, and its specific gravity was 2.7 10. Melting point1339 & ordm; C. Almost insoluble in water, soluble in water containing ammonium salt or iron oxide, insoluble in alcohol. Boil and dissolve when it meets dilute acetic acid, dilute hydrochloric acid and dilute nitric acid. Decomposition into calcium oxide and carbon dioxide by heating. Usage: According to the different grinding fineness, it is divided into four different specifications: single flying, double flying, three flying and four flying, which are used in various industrial departments respectively. Manufacturing method and process packing: packed in plastic bags, each with a net weight of 50 kg. Precautions for storage and transportation are stored in a dry warehouse. Prevent the bag from breaking during transportation. Do not mix with liquid acid. Light calcium carbonate Light calcium carbonate (precipitated calcium carbonate), light molecular formula CaCO3 molecular weight 100.09. Also known as precipitated calcium carbonate, light calcium for short, it is made by calcining limestone and other raw materials to generate lime (mainly calcium oxide) and carbon dioxide, adding water to digest lime to generate lime milk (mainly calcium hydroxide), then introducing carbon dioxide to carbonize the lime milk to generate calcium carbonate precipitate, and finally dehydrating, drying and pulverizing. Or firstly, performing double decomposition reaction on sodium carbonate and calcium chloride to generate calcium carbonate precipitate, and then dehydrating, drying and pulverizing the calcium carbonate precipitate. Because the sedimentation volume of light calcium carbonate (2.4-2.8mL/g) is larger than that of heavy calcium carbonate (1.1-1.4 ml/g), it is called light calcium carbonate. Description: White powder. Tasteless and odorless. The specific gravity is about 2.7 1. From 825 to 896.6 & ordmc decomposition. Melting point1339 & ordm; C. There are two forms: amorphous and crystalline, and crystalline can be divided into orthorhombic system and hexagonal system, columnar or rhombic. Insoluble in water and alcohol. Dissolving in acid, releasing carbon dioxide at the same time, showing an exothermic reaction. Also dissolved in ammonium chloride solution. Stable in air, with slight hygroscopicity. Uses: It can be used as filler in rubber, plastic, paper, paint, ink and other industries. Widely used in organic synthesis, metallurgy, glass and asbestos production. It can also be used as a seed agent for industrial wastewater, an antacid for gastric and duodenal ulcers, an antidote for acidosis, a sulfur dioxide eliminator for waste gas containing sulfur dioxide, a feed additive for dairy cows and an anti-sticking agent for linoleum. It can also be used as raw materials for cosmetics such as tooth powder and toothpaste. The manufacturing method and carbonization process: limestone and white coal are mixed according to a certain proportion, calcined at high temperature, boiled in water, carbonized with carbon dioxide, centrifugally dehydrated, dried, cooled, crushed and sieved to obtain the finished product. CaCO3 = = Cao+CO2 ↑ Cao+H2O → Ca (OH) 2 Ca (OH) 2+CO2 → CaCO3 ↓+H2O Packaging: packed in gunny bags or plastic bags. The net weight of each bag is 50 kg or 25 kg. Precautions for storage and transportation: Store in a dry place. Avoid contact with acids. Be careful when transporting, and the packaging should not be scattered. Pay attention to moisture. According to the particle size of powder, calcium carbonate product is a kind of powder. According to the average particle size (d) of calcium carbonate powder, calcium carbonate can be divided into fine calcium carbonate (d >: 5μm) and calcium carbonate powder (1 μ m).