Name | Calcium carbide |
Synonyms | Calciumcarbid carburocalcico Quartz crystal Calcium carbide calciumdicarbide carburedecalcium calcium acetylide calcium ethynediide calciumcarbide(cac2) carburedecalcium(french) Calcium Carbide, 10-40 Mesh Calcium Carbide, Anhydrous Calciumcarbidemetallurggradegreylumpsmm |
CAS | 75-20-7 |
EINECS | 200-848-3 |
InChI | InChI=1/C2H2.Ca/c1-2;/h1-2H;/q;+2 |
InChIKey | UIXRSLJINYRGFQ-UHFFFAOYSA-N |
Molecular Formula | C2Ca |
Molar Mass | 64.1 |
Density | 2.22g/mLat 25°C(lit.) |
Melting Point | 447°C |
Boling Point | 2300°C |
Water Solubility | hydrolyses |
Appearance | pieces |
Specific Gravity | 2.22 |
Color | Gray-black |
Exposure Limit | ACGIH: TWA 2 mg/m3OSHA: TWA 5 mg/m3NIOSH: IDLH 25 mg/m3; TWA 2 mg/m3 |
Merck | 14,1656 |
BRN | 3909011 |
Storage Condition | water-free area |
Stability | Stability Reacts violently with water liberating highly flammable gas (acetylene). Do not use water if this material is involved in a fire. Incompatible with moisture, water, strong oxidizing agents, |
Sensitive | Moisture Sensitive |
Physical and Chemical Properties | Industrial traits are gray, yellow-brown or black solid, containing calcium carbide higher purple. melting point 2300 ℃ relative density 2.22 |
Use | For the production of acetylene gas, polyvinyl chloride, lime nitrogen, dicyandiamide, iron and steel desulfurization agent |
Hazard Symbols | F - Flammable |
Risk Codes | R15 - Contact with water liberates extremely flammable gases R41 - Risk of serious damage to eyes R37/38 - Irritating to respiratory system and skin. |
Safety Description | S8 - Keep container dry. S43 - In case of fire use ... (there follows the type of fire-fighting equipment to be used.) S43A - S39 - Wear eye / face protection. S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. |
UN IDs | UN 1402 4.3/PG 2 |
WGK Germany | 1 |
FLUKA BRAND F CODES | 10-21 |
TSCA | Yes |
HS Code | 28491000 |
Hazard Class | 4.3 |
Packing Group | II |
industrial products are gray, yellow-brown or black solids that contain higher levels of calcium carbide in the purple color. The new fracture surface of calcium carbide is glossy, and the gloss is gray-white due to the absorption of moisture in the air. The relative density was 2. 22. Industrial products generally contain 80% calcium carbide. Melting point 2300 °c. Conductive, the higher the purity, the more conductive. The chemical properties are very active, and can react with many gases and solutions at appropriate temperatures. The intense decomposition in water produces acetylene gas and calcium hydroxide, and releases a large amount of heat. With chlorine, hydrogen chloride, sulfur, phosphorus, ethanol, etc. at high temperature can occur intense chemical reaction.
The Coke and lime are crushed, mixed and evenly added into a closed Calcium Carbide Furnace according to a certain ratio, and heated by electricity. The reaction at high temperature generates molten calcium carbide, and the calcium carbide flows from the furnace into the calcium carbide pot for cooling, crushing and packaging into the barrel.
acetylene gas can be generated by the interaction of calcium carbide and water, which is an important basic raw material for organic synthesis. Acetylene gas can be prepared from polyvinyl chloride, Chloroprene Rubber, calcium cyanamide, acetic acid, vinyl acetate ethanol and its derivatives, cyanide
Compound, dicyanamide and acetone, etc. Calcium carbide and nitrogen to generate lime nitrogen can be used as agricultural fertilizer. The use of calcium carbide to generate acetylene for metal cutting and welding.
EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
important chemical raw materials | calcium carbide is also called calcium carbide. Chemical formula cac2. An important chemical material produced by the chemical processing of limestone. In 1892, the French H. MESAN and the American T.L. Wilson developed the method of preparing calcium carbide by electric furnace reduction, and the United States realized industrial production in 1895. The nature of calcium carbide is related to its purity. Industrial products are mostly mixtures of calcium carbide and calcium oxide, and contain trace amounts of sulfur, phosphorus, nitrogen and other impurities. The color is gray, brown to black with the increase of impurity content. The melting point and conductivity decrease with the decrease of Purity. The purity of industrial products is generally 80%, and the melting point is 1800~2000. At room temperature does not react with air, but more than 350 deg C oxidation reaction, 600~700 deg C can react with nitrogen, the formation of calcium cyanamide. Calcium carbide reacts with water or water vapor to generate acetylene and release a large amount of heat: CaC2 2H2O → C2H2 Ca(OH)2 125185.32J,1Kg pure calcium carbide can produce 366l acetylene (15 ℃, 0.1MPa), therefore, the storage should be strictly waterproof, usually in a closed iron container, if necessary, in a dry warehouse in the nitrogen storage. The electric furnace reduction method is the only method to produce calcium carbide in industry at present. The calcium oxide and Coke are reduced at 2000~2200 ℃: CaO 3C → CaC2 CO-480644.64J, the generated molten calcium carbide flows into the receiving tank from the bottom of the reaction furnace, and the product is obtained after cooling. The production of calcium carbide is operated at high temperature, with more dust and large power consumption. In the 80 s, the power consumption per ton of industrial calcium carbide was 10~11GJ. In order to reduce the power consumption, the use of closed and large-scale Calcium Carbide Furnace, in order to reduce the heat loss and is conducive to the recycling of carbon monoxide. calcium carbide is mainly used as a raw material for the production of acetylene. Acetylene is an important basic organic chemical raw material. However, with the rise of petrochemical industry, acetylene used in organic chemical industry has been gradually provided by petrochemical industry. Metal cutting and welding of acetylene generators using calcium carbide. Where there is no electricity, the stone lamp is used as the light source. Calcium cyanamide is produced industrially by heating calcium carbide in ammonia, the latter being nitrogen fertilizers, plant defoliants and herbicides. With the development of acetylene chemical industry, the output of calcium carbide in China increased from 30,000 tons in to 1.808 million tons in, ranking first in the world. But the production technology is still relatively backward, the majority of small open furnace, high energy consumption, pollution is more serious. In order to reduce the energy consumption, the modern calcium carbide production uses the closed type large-scale electric furnace, in order to reduce the heat loss and is conducive to the recycling of carbon monoxide. |
physical properties | Chemically pure calcium carbide is almost colorless and transparent crystals, and the color of the quenched steel. Industrial calcium carbide according to its purity is divided into: gray, brown or black. The Crystal section is gray, purple when the purity is high. The new section of calcium carbide has a glossy surface, which will lose its luster and become gray-white when exposed to the air due to the absorption of moisture in the air. Calcium carbide is actually an impure calcium carbide, containing lime and a small amount of silica, alumina, calcium sulfide, calcium phosphide and other impurities, CaC2 content of 85% of the chemical composition of calcium carbide: CaC 285.17%, caO 10.60%,SiO2 2. 34%,(Fe2O3 + Al2O3) 2.55%,MgO 0.15%. The density decreased with the increase of CaC2 content. Its melting point varies with the content of CaC2, the melting point of pure CaC2 is 2300 ℃; Industrial calcium carbide generally contains 280% CaC, its melting point is about 2000 ℃; Calcium carbide containing 269% CaC has the lowest melting point, 1750 ℃; When the CaC2 content is reduced again, the melting point increases, and then drops to 1800 ℃ (equivalent to 235.6% CaC), between 1750 °c and 1800 °c there is a maximum temperature of 1980 °c (corresponding to a CaC content of 252.5%), when CaC2 is less than 35.6%, the melting point rises again. |
reaction with water | calcium carbide reacts immediately with water to generate acetylene and calcium hydroxide, this is the industrial process of acetylene (calcium carbide method), the reaction formula: CaC2 2H2O = C2H2 Ca(OH)2. because the calcium carbide is not pure, the prepared acetylene gas is mixed with a small amount of gas impurities such as hydrogen sulfide and phosphine, so it has an unpleasant odor. Calcium carbide is prepared from Coke and quicklime in an electric furnace at a high temperature of 3000 °c: 3C CaO = CaC2 CO. when acetylene is prepared in the laboratory, due to the relatively severe reaction between calcium carbide and water, saturated salt water can be used to replace water, so that stable and pure acetylene gas flow can be obtained, and sodium chloride and calcium carbide do not react. |
hazard characteristics | calcium carbide in the air can absorb moisture, can be conductive, the higher the purity, the more conductive. Water or water vapor can occur flammable and explosive acetylene gas (commonly known as calcium carbide gas), the gas spark can fire, will also be the reaction of the heat ignition. Acetylene gas and certain heavy metal salts can be discharged into advanced explosive mixtures. Calcium carbide often contains phosphorus, sulfur and other impurities, and water will also release phosphine and hydrogen sulfide and other toxic gases. When the content of phosphine is more than 0.08% and the content of hydrogen sulfide is more than 0.15%, it is easy to cause spontaneous combustion and explosion. The powder is irritating to the eyes and respiratory organs, causing skin burns. Calcium carbide is one of the basic raw materials for organic synthesis industry. It can generate acetylene gas, which is used for welding and cutting metal, and is also the raw material for manufacturing polyvinyl chloride. Dust can make the skin irritation symptoms, the formation of impurities, especially hydrogen sulfide and phosphine can be poisoned. In addition, it is also classified as a dangerous product because it is easy to generate flammable and explosive acetylene in water. Should be stored in a cool, ventilated, dry place, the place does not allow water leakage, handling should be light, handling, transport tools must have waterproof equipment, away from steel and copper alloy and salts. After loading and unloading should be done in the transport, it is strictly prohibited to install on the deck, to avoid sun exposure, no water and foam when fire fighting, dry powder and dry sand can be used, carbon dioxide is invalid. People immediately after poisoning should be moved to the fresh air, with 5% carbon dioxide containing oxygen to help breathing. This product is made of quicklime such as anthracite or Coke, which is heated to high temperature in an electric furnace. United Nations No.: 1402/4335/4.3-03/705. Domestic product number: 43025. |
Use | for the production of acetylene gas, polyvinyl chloride, lime nitrogen, dicyandiamide, used in electronic industry used as teaching reagent calcium carbide used in chemical production accounted for about 60%, the remaining 40% for metal welding and cutting. With calcium carbide as raw material can produce a series of chemical products, such as PVC resin, polyvinyl alcohol, vinyl acetate, Chloroprene Rubber, butanol, octanol, three cyanoethylene, four cyanoethylene, acetaldehyde, acetylene carbon black, lime nitrogen. The largest amount is the production of PVC resin, accounting for 60% of the consumption of chemical calcium carbide. Calcium carbide powder is irritating and can damage the skin and respiratory system. |
production method | electric furnace reduction method is currently the only method for the industrial production of calcium carbide. This method as early as 1895 in the United States to achieve industrial production, production of high temperature operation, more dust, large power consumption, process improvement can improve operating conditions, reduce heat loss and improve the recovery of carbon monoxide, closed and large-scale Calcium Carbide Furnace is used. The Coke and lime are crushed, mixed evenly in a closed Calcium Carbide Furnace according to the ratio, heated by electricity, and the reduction reaction is carried out at 2000-2200 ° C. To generate molten calcium carbide, which is cooled, crushed and packaged by flowing into a calcium carbide pot from the furnace. Kg/ton of Coke (fixed carbon 84%) 550 limestone (CaO 92%) 840 electrode paste 30 electricity 3200 (deg/ton) |
category | water burning articles |
explosive hazard characteristics | the mixture of acetylene and oxidant emitted in water |
flammability hazard characteristics | acetylene gas is combustible when exposed to water; A small amount of toxic hydrogen sulfide is released when exposed to water, phosphine gas |
storage and transportation characteristics | The warehouse is ventilated and dried at low temperature; Stored separately from oxidant and strong acid |
extinguishing agent | dry powder, dry sand, dry powder |
toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |