Applications calcium carbide

Acetylene was discovered m 1836 by Edmund Davy and characterized by the French chemist P E M Berthelot m 1862 It did not command much attention until its large scale preparation from calcium carbide m the last decade of the nineteenth century stim ulated interest m industrial applications In the first stage of that synthesis limestone and coke a material rich m elemental carbon obtained from coal are heated m an electric furnace to form calcium carbide... 

Desulfogypsum, 4 591-593, 595 Desulfurization, 1 650 10 785 Desulfurizing reagents, calcium carbide application, 4 549-550 Deswelling process, for solvent removal, 28104... 

One of the most important discoveries in the history of the chemical industry in Ontario was accidental. Thomas Carbide Willson (1860-1915) was trying to make the element calcium from lime, CaO, by beating tbe lime with coal tar. Instead, he made the compound calcium carbide, CaC2. This compound reacts with water to form a precipitate of calcium hydroxide and gaseous ethyne (acetylene). Willson s discovery led to the large-scale use of ethyne in numerous applications. 

This paper will discuss how some foundries have evaluated the application of these waste management options for calcium carbide desulfurization slag and melt emission control residuals. 

Ferrosilicon - [CARBON - CARBON AND ARTIFICIALGRAPHITE - APPLICATIONS OF BAKED AND GRAPHITIZED CARBON] (Vol 4) - [SILICON AND SILICON ALLOYS - CHEMICAL AND METALLURGICAL] (Vol21) - [METALLURGY - EXTRACTIVE METALLURGY] (Vol 16) - [MINERALS RECOVERY AND PROCESSING] (Vol 16) - [SILICON COMPOUNDS-SILANES] (Vol 22) -as calcium carbide impurity [CARBIDES - CALCIUM CARBIDE] (Vol 4)... 

The synthesis of acetaldehyde by oxidation of ethylene, generally known as the Wacker process, was a major landmark in the application of homogeneous catalysis to industrial organic chemistry. It was also a major step in the displacement of acetylene (made from calcium carbide) as the feedstock for the manufacture of organic chemicals. Acetylene-based acetaldehyde was a major intermediate for production of acetic acid and butyraldehyde. However the cost was high because a large energy input is required to produce acetylene. The acetylene process still survives in a few East European countries and in Switzerland, where low cost acetylene is available. 

Source of Heat Industrial furnaces are either fuel-fired or electric, and the first decision that a prospective furnace user must make is between these two. Although electric furnaces are uniquely suited to a few applications in the chemical industry (manufacture of silicon carbide, calcium carbide, and graphite, for example), their principal use is in the metallurgical and metal-treatment industries. In most cases the choice between electric and fuel-fired is economic or custom-dictated, because most tasks that can be done in one can be done equally well in the other. Except for an occasional passing reference, electric furnaces will not be considered further here. The interested reader will find useful reviews of them in Kirk-Othmer Encyclopedia of Chemical Technology (4th ed., vol. 12, articles by Cotchen, Sommer, and Walton, pp. 228-265, Wiley, New York, 1994) and in Marks Standard Handbook for Mechanical Engineers (9th ed., article by Lewis, pp. 7.59-7.68, McGraw-Hill, New York, 1987). 

All technical processes for the synthesis of hydrazine yield either hydrazine in aqueous solution or hydrazine hydrate. Most applications can use hydrazine hydrate, but for some applications, for example, rocket propulsion, anhydrous hydrazine is necessary. The water can be removed by a chemical reaction followed by distillation or by azeotropic distillation with an auxiliary fluid. As water binding chemicals, calcium carbide, sodium hydroxide, calcium oxide, calcium hydride, barium oxide, barium hydroxide, and barium pemitride Ba3N4 have been used. The use of sodium or calcium metal and sodium amide is best avoided because of the formation of explosive hydrazides. Starting from hydrazine hydrate (64% hydrazine), sodium hydroxide is generally used... 

Major producers manufacture acetylene by either the partial oxidation of natural gas or as a coproduct of the thermal cracking of ethylene minor producers manufacture acetylene from calcium carbide. About 80% of production is used as a closed system intermediate in the manufacture of acetylene black as well as acetylenic and vinyl derivatives used in a variety of applications such as the manufacture of plastics. The remaining 20% is used primarily in oxyacetylene torches for welding and metal cutting. Although acetylene was used as an anesthetic in the early 1900s, this use has fallen into disfavor due to the explosive properties of acetylene. 

Technical data concerning applications, safe practices, handling, storing, and use of industrial gases, calcium carbide, and acetylene and its allied products are assembled by the International Acetylene Association, of New York, for its membership. 

Acetylene was discovered by the British chemist Edmund Davy (1785-1857) in 1836. Davy obtained the gas accidentally when he combined water with potassium carbide (KCH2) while attempting to make potassium metal. He noted that the gas burned with a bright flame and thought it might he used as a source of illumination. That application was impractical, however, because of the high cost of potassium carbide. When the German chemist Frederich Wohler (1800-1882) discovered the far less expensive calcium carbide... 

The conversionfrom tricalcium phosphate to elementary phosphoras was close to 100%. The process was performed in a plasma fluidized bed supported by argon flow at 1030-1200°C. Mosse and Pechkovsky (1973) applied CH4 as a plasma gas and reduction agent for processing tricalcium phosphate. The reaction was conducted in an atmospheric-pressure CH4 plasma jet at 3000 000 K, the residence time was 0.01-0.05 s, and the phosphate-to-CH4 ratio was 1 10. The conversion degree from Cas (P04)2 to elementary phosphoras was up to 75%. Gas-phase by-products included acetylene and other hydrocarbons, PH3, CO, and CO2 solid-phase by-products included mostly calcium carbide and phosphide. Another major compound of natural phosphates is fluoroapatite, Ca5p(P04)3. Practical applications... 

The pyrolysis products are quite stable in this case. This plasma process also has an advantage compared to the conventional process described by the same chemical formula (10-35). The conventional process requires the application of coke, whereas the plasma-chemical one starts directly from coal. In the experimental system of plasma production of calcium carbide (CaC2), the size of the coal particles is 8-44 pm and the molar ratio between carbon (of coal) and CaO is in the range 1-3. The experimentally achieved conversion degree in the optimal regime of the process is 90% for caibon and 70% for CaO. Achieving higher... 

Silicon accounts for 27.7% of the mass of the Earth s crust and occurs in a wide variety of silicates with other metals, clays, micas, and sand, which is largely Si02. The element is obtained on a small scale by the reduction of silicon(IV) oxide (Si02) by carbon or calcium carbide. For semiconductor applications very pure silicon is produced by direct reaction of silicon with an HCI/CI2 mixture to give silicon tetrachloride (SiCb), which can be purified by distillation. This is then decomposed on a hot wire in an atmosphere of hydrogen. For ultra-pure samples zone refining is used. Unlike carbon, silicon does not form allotropes but has only the diamond type of structure. 

From 1930, ICI undertook research into polyvinylchloride, but despite its popularity in other countries did not embark on manufacture. There was, understandably, no reason to do so, since natural rubber for electrical insulating applications was available in abundance, and calcium carbide, the source of starting acetylene, was, as Herbert... 

Typical of those patents was U.S. Patent 541 137, June 18, 1895. It claims "An Improved Calcium-Carbide Process". The electric -furnace is described. An intimate 35 65 mixture of finely powdered coke and lime is to be heated. The calcium carbide is obtained by raising one electrode to which it adheres or by tapping the carbon-lined furnace at the bottom. The applicant emphasizes the advantage of using an alternating current, because thereby the charge readily and automatically feeds between the electrodes. 

Ivakhnyuk, G.K. et al. Carbon enriched calcium carbide and possibihty of its application. Zhumal... 

---