Chalk

Classification：Sedimentary Rock

A soft, fragile and porous limestone is formed by the accumulation of marine Paleontology (algae and foraminifera) debris. The most famous Cretaceous comes from the Cretaceous strata. It is usually symbiotic with flint.

Chalk is an inorganic compound, commonly known as limestone, limestone, stone powder, marble and so on. Main component: calcite is a compound, its chemical formula is CaCO, it is neutral, basically insoluble in water, soluble in hydrochloric acid. It is a common substance on the earth. It is found in aragonite, calcite, chalk, limestone, marble, Shi Huihua and other rocks. It is also the main component of animal bones or shells. Chalk is an important building material and widely used in industry. Chalk is composed of calcium and carbonate ions combine to form, so it is also calcium carbonate.

Physical property：
White solid, tasteless, odorless. There are two forms of amorphous and crystalline form. In crystalline form, it can also be divided into orthorhombic system and six square crystal system. The relative density is 2.71. Decomposition at 825 to 896.6 degrees, and decompose to calcium oxide and carbon dioxide at about 825 degrees. The melting point is 1339 C, and the melting point at 10.7MPa is 1289. It is difficult to dissolve in water and alcohol. It dissolves in dilute acid and releases carbon dioxide at the same time, showing exothermic reaction. It is also dissolved in ammonium chloride solution. Almost insoluble in water. Aragonite: relative density is 2.83, melting point is 825 degrees (decomposition). Calcite: relative density (d25.2) 2.711, melting point 1339 degrees (10.39MPa). It is irritant and Chalk is divided into two types: synthetic and natural. It is stable in the air and has a slight moisture absorption capacity. Good covering power. It's a strong electrolyte.

Classification of production methods:
According to the different production methods of Chalk, Chalk can be divided into heavy Chalk, light Chalk, colloidal Chalk and crystal Chalk.

Heavy quality Chalk:
(commonly known as heavy calcium) is a mechanical method (using Raymond mill or other high pressure mill) to directly crush the natural calcite, limestone, chalk, shell, etc. can be made. Because the settlement volume of heavy Chalk is smaller than that of light Chalk, it is called heavy Chalk. Nature: white powder. Odorless, tasteless. There is no change in the exposed air, and the proportion of the air is 2.710. The melting point is 1339 degrees centigrade. Almost insoluble in water containing ammonium salt or ferric oxide dissolved in water, insoluble in alcohol. Dilute acetic acid, dilute hydrochloric acid and dilute nitric acid boil and dissolve. The heating is decomposed into calcium oxide (CaO) and carbon dioxide (CO2).
Purpose: according to the difference of crushing fineness, the industry is divided into four different specifications: single flying, double flying, three flying, and four flying, which are used in various industrial sectors respectively.
Solo powder: used in the production of anhydrous calcium chloride (CaCl2), is the auxiliary materials of sodium dichromate production. The main raw materials for the production of glass and cement. In addition, it is also used for building materials and poultry feed.
Twin fly powder is the raw material for producing anhydrous calcium chloride and glass, white filler for rubber and paint, and building materials.
Three, flying powder: used as filler for plastic, paint, putty, paint, plywood and paint.
Four flying powder: used as filler for wire insulation, rubber moulded products and filler for asphalt felt.
Process and process flow
Comminution: it is a finished product that is crushed, graded and separated by using Raymond mill or other high pressure mill, which contains more than 90% CaCO3 of white stone.
Packing: packing in plastic bags with net weight of 50 kilograms per bag.
The precautions for storage and transportation are stored in the dry storeroom. To prevent bags from breaking in transportation. It is not allowed to mix with liquid acids.

Light Chalk:
Also called precipitation Chalk, short for light calcium, it is calcined limestone and other raw materials to produce lime (mainly calcium oxide) and carbon dioxide, and then add water to digest lime to produce lime milk (mainly calcium hydroxide) and then carbon dioxide carbonated lime milk to produce Chalk precipitation, and finally dehydrated, dried and comminuted. It is made. Or first, we use sodium carbonate and calcium chloride to form Chalk precipitation and then dehydrate, desiccate and crush. Because the settlement volume (2.4-2.8mL/g) of lightweight Chalk is larger than the settling volume of heavy Chalk (1.1-1.9mL/g), it is called lightweight Chalk.
Nature: white powder. Tasteless and odorless. The proportion is about 2.71. Decomposed at 825 to 896.6 degrees C. The melting point is 1339 degrees centigrade. There are two forms of amorphous and crystalline form. They can be divided into orthorhombic system and six square crystal system. It is difficult to dissolve in water and alcohol. It is soluble in acid and emitted carbon dioxide at the same time, showing exothermic reaction. It is also dissolved in ammonium chloride solution. It is stable in the air and has a slight moisture absorption capacity.
Application: it can be used as filler in rubber, plastics, paper making, coating and printing industries. It is widely used in organic synthesis, metallurgy, glass and asbestos production. It can also be used as a medium agent for industrial wastewater, an acid making agent for gastric and duodenal ulcers, an acidosis antidote, a SO containing SO? Elimination agent in the exhaust gas, a cow feed additive and an anti felting agent for felt. Can also be used as a dentifrice, toothpaste and other cosmetics raw materials.

Process and process:
Carbonization: after mixing limestone and white coal in a certain proportion, the product is calcined at high temperature, digested by water, carbonated by carbon dioxide, and then by centrifuge dehydration, drying, cooling, crushing and screening.
CaCO = =CaO+CO = temperature
CaO+H O=Ca (OH)
Ca (OH) +CO ===CaCO +H: O
Packing: packing in a sack or a plastic bag. The net weight of each bag is 50 kg or 25 kilograms.
Precautions for storage and transportation: stored in the dry place. Avoid contact with acids. In transportation, be careful not to pack. Pay attention to moisture-proof.