Calcium carbide, also known as calcium acetylide, is a chemical compound with the chemical formula of CaC2. Its main use industrially is in the production of acetylene and calcium cyanamide.
Calcium carbide is produced industrially in an electric arc furnace from a mixture of lime and coke at approximately 2,200 C (3,990 F). This is an endothermic reaction requiring 110 kilocalories (460 kJ) per mole and high temperatures to drive off the carbon monoxide. This method has not changed since its invention in 1892:
The high temperature required for this reaction is not practically achievable by traditional combustion, so the reaction is performed in an electric arc furnace with graphite electrodes. The carbide product produced generally contains around 80% calcium carbide by weight. The carbide is crushed to produce small lumps that can range from a few mm up to 50 mm. The impurities are concentrated in the finer fractions. The CaC2 content of the product is assayed by measuring the amount of acetylene produced on hydrolysis. As an example, the British and German standards for the content of the coarser fractions are 295 L/kg and 300 L/kg respectively (at 101 kPa pressure and 20 C (68 F) temperature). Impurities present in the carbide include phosphide (fosgen), which produces phosphine when hydrolysed.
This reaction was an important part of the industrial revolution in chemistry, and was made possible in the United States as a result of massive amounts of inexpensive hydroelectric power produced at Niagara Falls before the turn of the 20th century.The electric arc furnace method was discovered in 1892 by T. L. Willson, and independently in the same year by H. Moissan. In Jajce, Bosnia and Herzegovina, the Austrian industrialist Josef Kranz and his "Bosnische-Elektrizitäts AG" company, whose successor later became "Elektro-Bosna", opened the largest chemical factory for the production of calcium carbide at the time in Europe in 1899. A hydroelectric power station on the Pliva river with an installed capacity of 8 MW was constructed to supply electricity for the factory, the first power station of its kind in Southeast Europe, and became operational on 24 March 1899.
In China, acetylene derived from calcium carbide remains a raw material for the chemical industry, in particular for the production of polyvinyl chloride. Locally produced acetylene is more economical than using imported oil. Production of calcium carbide in China has been increasing. In 2005 output was 8.94 million tons, with the capacity to produce 17 million tons.
Calcium carbide is used in carbide lamps. Water dripping on carbide produces acetylene gas, which burns and produces light. While these lamps gave steadier and brighter light than candles, they were dangerous in coal mines, where flammable methane gas made them a serious hazard. The presence of flammable gases in coal mines led to miner safety lamps such as the Davy lamp, in which a wire gauze reduces the risk of methane ignition. Carbide lamps were still used extensively in slate, copper, and tin mines where methane is not a serious hazard. Most miners' lamps have now been replaced by electric lamps.
Calcium carbide is sometimes used as source of acetylene, which like ethylene gas, is a ripening agent. However, this is illegal in some countries as, in the production of acetylene from calcium carbide, contamination often leads to trace production of phosphine and arsine. These impurities can be removed by passing the acetylene gas through acidified copper sulfate solution, but, in developing countries, this precaution is often neglected.
Calcium carbide is used to determine the moisture content of soil. When soil and calcium carbide are mixed in a closed pressure cylinder, the water content in soil reacts with calcium carbide to release acetylene whose pressure can be measured to determine the moisture content.
The fast ripening of fruits means they may contain various harmful properties. A commonly used agent in the ripening process is calcium carbide, a material most commonly used for welding purposes. Calcium carbide treatment of food is extremely hazardous because it contains traces of arsenic and phosphorous. Once dissolved in water, the carbide produces acetylene gas. Acetylene gas may affect the neurological system by inducing prolonged hypoxia. The findings are headache, dizziness, mood disturbances, sleepiness, mental confusion, memory loss, cerebral edema and seizures. We report the case of a previously healthy 5 year-old girl with no chronic disease history who was transferred to our Emergency Department with an 8-h history of coma and delirium. A careful history from her father revealed that the patient ate unripe dates treated with calcium carbide.
Acetylene (C2H2) gas is widely used for ripening fruit in agriculture and for welding in industry, while the by-product (CCR) is often discarded as waste in landfills and thus poses a threat to the environment. For example, in China, as much as 2500 tons of CCR is generated annually . CCR is mainly composed of calcium hydroxide with a mass fraction of above 92% and is highly alkaline (pH > 12). It has been found that mixing CCR with certain pozzolans, which have high silicon dioxide (SiO2) or aluminum oxide (Al2O3) content, could yield pozzolanic reactions, resulting in final products that are similar to those obtained from the cement hydration process .
Calcium carbide, a chemical compound used in the commercial manufacture of acetylene gas, was discovered accidentally during experiments in aluminum processing in Spray (now Eden) in Rockingham County. A local entrepreneur, James Turner Morehead, formed a partnership with Thomas L. Willson, a Canadian chemist, to develop an economical method for producing aluminum. Using existing water-power resources in Spray, the Willson Aluminum Company constructed the first electric arc furnace in the United States to procure the high temperatures necessary to reduce aluminum. Combining aluminum oxide and carbon in the furnace was not successful, but the company did commercially produce alloys of copper and aluminum.
In the course of the experimentation, a mixture of lime and coal tar was introduced with calcium for the purpose of producing metallic calcium as a reduction agent in the aluminum process. Following the routine procedure of quenching the results in water for rapid cooling, a large quantity of gas was observed on 2 May 1892. Morehead's son, John Motley Morehead III, a chemistry graduate of the University of North Carolina in Chapel Hill, identified the new substance as calcium carbide. Lacking gas analysis equipment, they sent a sample to Chapel Hill, where Professor F. P. Venable and an assistant, William Rand Kenan, identified the gas as acetylene. In spite of initially lacking a practical use for the new compound or gas, the elder Morehead continued to produce and experiment, believing that the gas had commercial possibilities for energy and especially lighting use. His heavily mortgaged businesses were lost in the panic of 1893, and he was left with little more than samples of calcium carbide.
In 1894 Morehead and Willson convinced New York investors to form the Electric Gas Company to produce calcium carbide and acetylene. Additional experimentation in Spray with alloys led to the development of ferrochromium and ferrosilicon, which were used in the hardening of steel. These steel alloys were important in the development of armor plate and armor-piercing projectiles, which were significant in the late nineteenth-century naval arms buildup. Later power development by Morehead on the James River in Virginia and the Kanawba River in West Virginia, as well as patents in chemical processes and metal alloys, led to the formation of Union Carbide Corporation in Chicago in 1898. Union Carbide was founded with the purpose of producing acetylene gas for use in household lighting and streetlamps, providing an alternative to coal gas and kerosene. The company expanded into producing oxyacetylene for welding in 1911. The 1917 merger of Union Carbide, Linde Air Products, Prest-O-Lite Company, and National Carbon Company created Union Carbide and Carbon Corporation, which quickly developed into a producer of petrochemicals, metal alloys, antifreeze, and synthetics. The company is also known for its role in the horrific 1984 pesticide plant disaster that killed 3,500 people in Bhopal, India.
Substances which, in contact with water, emit flammable gases - Category 11
Combustible dusts - See comments below2
Skin corrosion/irritation - Category 23 4 5
Serious eye damage/eye irritation - Category 13 6 7 8
Forms a corrosive substance upon contact with water: calcium hydroxyde
Specific target organ toxicity - single exposure (respiratory tract irritation) - Category 3 - Respiratory tract irritation6 7 8
Acetylene (C2H2) is the world's most efficient and hottest burning standard welding gas. For producing acetylene, the reaction of calcium carbide (CaC2) with water (H2O) is used, whereas acetylene and lime milk (Ca(OH)2) is generated.
For this simple and proven process, AlzChem's calcium carbide is used for more than a century. Calcium carbide is of strategic value for AlzChem, as it is the basis of the NCN-chain. Originating from calcium carbide, AlzChem produces a variety of products from fertilizer to specialty chemical at five production sites.
In order to ensure the availability of calcium carbide at any time, AlzChem produces it with three electric arc furnaces at two sites. With this redundant production of calcium carbide, we can guarantee our customers the highest level of supply security and reliability.
Leading producers of technical gases rely on the holistic offer of AlzChem. Besides high and stable product quality, AlzChem organizes logistics with their own carbide containers and rail wagons and offers qualified support for technical questions. 041b061a72