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The chemical name of calcium carbide is calcium carbide (CaC2), and the main component is CaC2, accounting for 70 ~ 80% of the total content of calcium carbide. The remaining component Cao accounts for about 20%, and others such as C, Si and Fe account for about 6%. Calcium carbide is an inorganic compound, white crystal, industrial product is gray black block, and the section is purple or gray. In case of water, it immediately reacts violently to generate acetylene and release heat.
1、 Calcium carbide reacts with water to produce acetylene gas
The chemical property of calcium carbide is very active. It decomposes violently in contact with water to produce acetylene gas to synthesize many organic compounds and release a lot of heat. For example: synthetic rubber, artificial resin, acetone, ketene, carbon black, etc; At the same time, acetylene oxygen flame is widely used in metal welding and cutting. Acetylene gas can also be processed into propargyl alcohol (C3H4O) for pharmaceutical use.
2、 Production of polyvinyl chloride (PVC)
Calcium carbide method is used to produce polyvinyl chloride. Acetylene (C2H2) is generated by calcium carbide (CaC2) in water. Vinyl chloride monomer (CH2 = CHCl) is synthesized from acetylene and hydrogen chloride (HCl), and then vinyl chloride is generated into polyvinyl chloride - [ch-chci] n - through polymerization.
3、 Calcium carbide desulfurizer / deoxidizer
Calcium carbide is an economic and efficient desulfurizing and deoxidizing agent in iron and steel production. Calcium carbide is usually used to reduce FeO, Cr2O3 and MnO in slag in steelmaking and refining process. That is the so-called white slag making process. When fine calcium carbide is added to the slag, CaC2 is decomposed into calcium and carbon. Carbon continues to produce CO2 gas in the reaction of FeO, MnO and Cr2O3 in the reduction slag, so as to form foams in the slag. The foaming slag means that the thickness of the slag increases and produces the arc burying effect. This brings three advantages. One is to protect the lining from prolonging life by arc radiation. Second, improve power input efficiency, save power consumption and shorten smelting time. The third is to form a reducing atmosphere, reduce the secondary oxidation of molten steel to the air and absorb water in the air. Calcium is a strong reducing agent, which can reduce FeO and Cr2O3 in slag to the greatest extent. After the formation of white slag, it can react directly with sulfur in molten steel to form CAS. Therefore, someone mixed calcium carbide with lime, bauxite and fluorite as desulfurizer. Good fluidity, fast desulfurization and deoxidation reaction speed, strong desulfurization depth, shortening (refining) reduction time, small molten steel temperature drop, small desulfurizer consumption and reducing material consumption. Due to the reasonable price, it has become an alternative product of aluminum in the iron and steel industry. Desulfurization and deoxidation of primary molten steel can not only reduce the consumption of aluminum, reduce the inclusion of alumina, but also reduce the cost. Compared with the reducing agent silicon carbide, the reduction ability is strong, and the weakness of reducing slag alkalinity by silicon carbide reduction is avoided. It is best used in electric furnace, refining furnace and converter to save energy and reduce cost in iron and steel industry. Because of its excellent desulfurization and deoxidation performance, it is also an ideal desulfurization and deoxidation agent in the foundry industry, which is widely used in the foundry industry.
4、 Calcium cyanamide is produced by calcium carbide reaction
When the powdered calcium carbide is heated with nitrogen, the reaction produces calcium cyanamide, that is, lime nitrogen. Lime nitrogen is an important raw material for the preparation of cyanamide. The melt formed by the reaction of heated lime nitrogen and table salt is used in gold mining and non-ferrous metal industry. Lime nitrogen is also an efficient soil disinfectant. Its disinfection principle refers to that the monocyandiamide and liquid dicyandiamide produced by the decomposition of calcium cyanide hydride in water have a broad-spectrum killing effect on harmful organisms such as fungi and bacteria in the soil, can control a variety of soil borne diseases and underground pests, and also has a certain control effect on root knot nematodes that have plagued the production of facility agriculture. In addition to quicklime, monocyandiamide and dicyandiamide, the intermediate products of calcium cyanamide decomposition, finally produce urea, which has the advantages of no residue and no environmental pollution. The prominent role of calcium cyanamide disinfection technology is to promote the decomposition of organic matter, improve soil structure, adjust soil acidity, eliminate soil hardening, increase soil permeability, reduce the harm of Cordyceps sinensis, and reduce the content of nitrite in vegetables.
Calcium carbide is mainly used in industrial gas, pharmacy, PVC, steel smelting, fluorine chemical raw materials, gold mining and non-ferrous metal industry, soil disinfectant, fruit ripening, etc. the domestic output is about 2.3 million tons / month.