Calcium carbonate,CAS 471-34-1

Calcium carbonate occurs in two forms—hexagonal crystal known as calcite, and orthorhombic form, aragonite. Calcite decomposes on heating at 825°C, aragonite melts at 1,339°C (at 102.5 atm). Density 2.71 g/cm3 (calcite), 2.83 g/cm3 (aragonite); insoluble in water (15mg/L at 25°C); Ksp 4.8x10–9 ; soluble in dilute mineral acids. Calcium carbonate occurs as an odorless and tasteless white powderor crystals.

Calcium carbonate appears as white, odorless powder or colorless crystals. Practically insoluble in water. Occurs extensive in rocks world-wide. Ground calcium carbonate (CAS: 1317-65-3) results directly from the mining of limestone. The extraction process keeps the carbonate very close to its original state of purity and delivers a finely ground product either in dry or slurry form. Precipitated calcium carbonate (CAS: 471-34-1) is produced industrially by the decomposition of limestone to calcium oxide followed by subsequent recarbonization or as a by-product of the Solvay process (which is used to make sodium carbonate). Precipitated calcium carbonate is purer than ground calcium carbonate and has different (and tailorable) handling properties.|DryPowder; DryPowder, Liquid; DryPowder, OtherSolid; DryPowder, PelletsLargeCrystals; DryPowder, PelletsLargeCrystals, Liquid; DryPowder, WetSolid; Liquid; OtherSolid; OtherSolid, Liquid; PelletsLargeCrystals; WetSolid; WetSolid, Liquid; WetSolid, OtherSolid|White crystalline or amorphous, odourless and tasteless powder|WHITE POWDER OR PELLETS.|White, odorless powder or colorless crystals. Calcium carbonate is soluble in concentrated mineral acids.|White, odorless powder or colorless crystals.|Limestone (calcium carbonate) that has been recrystallized by metamorphism and is capable of taking a polish. Practically insoluble in water.|Odorless, white to tan powder.|Odorless, white powder.

Calcium carbonate appears as white, odorless powder or colorless crystals. Practically insoluble in water. Occurs extensive in rocks world-wide. Ground calcium carbonate (CAS: 1317-65-3) results directly from the mining of limestone. The extraction process keeps the carbonate very close to its original state of purity and delivers a finely ground product either in dry or slurry form. Precipitated calcium carbonate (CAS: 471-34-1) is produced industrially by the decomposition of limestone to calcium oxide followed by subsequent recarbonization or as a by-product of the Solvay process (which is used to make sodium carbonate). Precipitated calcium carbonate is purer than ground calcium carbonate and has different (and tailorable) handling properties.|Calcium carbonate is a calcium salt with formula CCaO3. It has a role as an antacid, a food colouring, a food firming agent and a fertilizer. It is a calcium salt, a carbonate salt and a one-carbon compound.|Calcium carbonate is an inorganic salt used as an antacid. It is a basic compound that acts by neutralizing hydrochloric acid in gastric secretions. Subsequent increases in pH may inhibit the action of pepsin. An increase in bicarbonate ions and prostaglandins may also confer cytoprotective effects. Calcium carbonate may also be used as a nutritional supplement or to treat hypocalcemia.|Calcium Carbonate is the carbonic salt of calcium (CaCO3). Calcium carbonate is used therapeutically as a phosphate buffer in hemodialysis, as an antacid in gastric hyperacidity for temporary relief of indigestion and heartburn, and as a calcium supplement for preventing and treating osteoporosis. (NCI04)|Carbonic acid calcium salt (CaCO3). An odorless, tasteless powder or crystal that occurs in nature. It is used therapeutically as a phosphate buffer in hemodialysis patients and as a calcium supplement.

Calcium carbonate Use and Manufacturing
Methods of Manufacturing
1. Light calcium carbonate: from limestone to produce light calcium carbonate, including calcination, digestion, carbonation, separation, drying, grinding and other processes. Calcium carbonate content of raw materials in limestone should be more than 96%, about 1% magnesium salt, iron, aluminum oxide in 0.5% or less. Therefore, before use to select the limestone, and broken to 50 ~ 150mm. Coal requirements White coal, the first should be broken to 38 ~ 50mm particle size. Lime kiln for vertical kiln, continuous operation. The ratio of coal and limestone is 1: 8 ~ 1:11 mixed well, from the top into the kiln, at 900 ~ 1100 ℃ under calcination. The raw material is continuously added from the top of the kiln, and the generated calcium oxide is continuously taken out from the bottom of the kiln. Decomposition reaction of carbon dioxide generated by the dust, washing, drying, compression1. To the carbonization process. Calcium oxide added to the ash pool, with 3 to 5 times the water for digestion, digestion temperature of 90 ℃, time 1.5 ~ 2h. Digestion of lime milk concentration of 10 ~ 18 ° Bé. After filtering to remove impurities in the raw slurry storage tank, stirring sent to the carbonation tower, carbonation tower for vertical gas bubbling reactor. The refined carbon dioxide gas is compressed and introduced from the bottom of the carbonization tower, and enters the tower through the gas distributor, and comes into contact with the milk of the lime for carbonation reaction.Carbonization temperature is 60 ~ 70 ℃, carbonization pressure is about 0.08MPa, carbonation reaction time and the concentration of carbon dioxide, flow and liquid volume and different. The end point of carbonation can be determined by the determination of pH value, when the pH value of 7 or so, is the end. Carbonated calcium carbonate slurry is cooked pulp, placed in the cooked pulp pool, and then use the centrifuge dehydration, dehydration of calcium carbide after the water content of 32% to 42%, known as wet powder. The wet powder is continuously fed into a rotary drying furnace for drying, and the material discharged from the drying furnace contains less than 0.3% of water. And then cooled, crushed, sifted, that was finished.2. Activated calcium carbonate: production principle and production of light calcium carbonate is basically the same principle. Except that the carbonization conditions were strictly controlled to produce fine particles of calcium carbonate and surface treatment by adding 1 to 5% of stearic acid, resin acid, lignin or cationic surfactant to adjust the aggregation state of the particles and Prevent the growth of crystal particles. The stearic acid method is described as follows.(1) Preparation of glue 4.5kg36 ° Bé sodium hydroxide, add 70 ℃ hot water 40kg, stirring for the solution. After 15 kg of stearic acid and 40 kg of water were dissolved by heating, the solution was slowly added to the above-mentioned alkali solution with stirring to form sodium stearate. Then, 6 kg of Swire Oil was added. The solution was adjusted to neutral and water was added to a total weight of 162 kg. The amount of plastic for 3t finished surface treatment.(2) sizing operation in the production of light calcium carbonate in the process, from limestone calcination to carbonation of all equipment and operations are suitable for the production of activated calcium carbonate. The carbonated calcium carbonate slurries are put into a hot slurry tank, and the prepared sodium stearate oil is slowly added with stirring. Per ton of product plus plastic amount of 54kg, the finished product containing the ester content of 0.5%. Add the glue and continue stirring for a period of time, so that the material fully mixed.(3) post-treatment of sizing calcium carbonate after centrifugal dehydration, placed in the dryer, the first by natural or normal temperature ventilation to dry, so that water content down to 10% to 15%, and then drying at 80 ℃, Moisture content below 0.5%. And then the first 24-mesh sieve, and then 100 mesh sieve, that was finished. Heavy calcium carbonate: First, the CaCO3 containing more than 90% of the white crusher crusher in the rotary crusher, so that large rocks can be broken through the 76mm screen. And then finely pulverized in a hammer mill, a rotary hammer mill, a squirrel-cage pulverizer or a breaker, a rotary mill, a hard grinder or a wheel mill to break CaCO3 to pass through a 100 mesh screen. And finally pulverized by a Raymond vacuum mill or a gravel mill with a comminution collector and a vacuum tube. Air separation, that is, the use of counter-rotating or multi-leaf guide plate by centrifugal separation to remove the excessive size of the pellets. The material obtained by screening classification derived products.Reaction formula: -> -> 3. Calcium carbonate whisker method: Ca (OH) 2 slurry in advance by adding 1 ~ 2μm needle-like calcium carbonate whiskers and phosphate compounds, and then into the CO2 gas to be calcium carbonate whiskers. Or industrial lime for digestion, in a certain concentration of magnesium chloride solution, and then into the carbon dioxide gas for gas-liquid reaction, dehydration, drying to be calcium carbonate whiskers.4. Superfine light calcium carbonate system of law: usually using lime milk carbonation production of ultra-fine light calcium carbonate. Limestone is calcined and decomposed into quick lime and carbon dioxide. Quicklime digestion produces lime milk. Carbon dioxide is introduced into the milk of the lime, calcium carbonate is produced by the carbonation reaction, and a surface treatment agent is added to the calcium carbonate slurry to perform particle surface treatment. Then, filtration, drying, crushing and screening process in turn to get the product. Heavy calcium carbonate:(1) crushing method: Whitehead (natural limestone) in the jaw crusher in the first crushing, so that the block degree of 40-60mm, and then raised to the Raymond crusher crusher to crush. The pulverized semi-finished product is blown to a cyclone classifier by a blower and classified. The crude product is returned to the pulverizer for further processing. Qualified products by cyclone separation that is, the product. Superfine calcium carbonate:(2) grinding method: wet grinding calcium raw material is heavy calcium carbonate or white> 93 °, calcium> 98% calcite, the ingredients, wet grinding, pressure filtration, drying, packaging.(3) .Precipitation method: limestone calcination at high temperature to produce calcium oxide and carbon dioxide, lime water digestion in calcium hydroxide, lime milk after classification and purification of carbon dioxide reaction, carbonization crystallization by adding crystallization control agent to control the crystallization type, Or add emulsifier and surface treatment agent, so that the active agent and just the surface of calcium carbonate particles evenly covered, carbonized and then by centrifugal dehydration, drying, grading, packaging in the system. Reaction formula: -> ->

Uses
Used to improve the flexural resistance of PVC soft products. It is also widely used in rubber, adhesives and sealants as fillers and reinforcing agents; used as analytical reagents, reference reagents, silicon single crystal slice glue and thick film capacitor materials ; Mainly used as filling and reinforcing materials in rubber, plastics and coating industries; used in the production of cement, ceramics, lime, carbon dioxide, chalk, artificial stone, putty, and used as pigments, neutralizers, polishes, plastics and rubber Filler