bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cadmium and Cadmium Alloys
Authors: Morrow Hugh 
Published: July 2004

AbstractCadmium, Cd, a Group 12 (IIB) element occurring between zinc and mercury, is a soft, ductile, silver‐white metal having a distorted hexagonal close‐packed structure. The crustal abundance of cadmium is somewhere between 0.1 and 0.5 ppm, and several cadmium minerals have been identified, the most common being greenockite, CdS. Cadmium is generally encountered in zinc ores, zinc‐bearing lead ores, or complex copper‐lead‐zinc ores, where, however, it forms an isomorphic impurity in the zinc mineral sphalerite, ZnS. For this reason, cadmium is almost invariably recovered as a by‐product from the processing of zinc, lead, and copper ores. Its oxidation state in almost all of its compoumds is + 2, although a few compounds have been reported in which cadmium exists in the + 1 oxidation state. There are eight natural isotopes. Cadmium forms a fume of brown‐colored cadmium oxide, CdO, when heated in air. Other elements which react readily with cadmium metal upon heating include the halogens, phosphorus, selenium, sulfur, and tellurium. Cadmium is rapidly oxidized by hot dilute nitric acid. Cadmium occurs primarily as sulfide minerals in zinc, lead‐zinc, and copper‐lead‐zinc ores. Beneficiation of these minerals, usually by flotation or heavy‐media separation, yields concentrates which are then processed for the recovery of the contained metal values. Cadmium follows the zinc with which it is so closely associated. Air pollution problems and labor costs have led to the closing of older pyrometallurgical plants, and to increased electrolytic production. Cadmium production is dependent on the processing of zinc ores, which often contain 0.2 to 0.4% cadmium. Cadmium is classified as a toxic metal. Acute industrial poisoning by cadmium dust or fume can occur during the melting or pouring of cadmium metal; the welding, burning, or heating of cadmium‐plated steel; or spraying, brazing, and overheating of cadmium metal. Protection should be provided by a properly designed exhaust ventilation system or by a suitable individual filter or air‐supplied respirator. Industrial exposure to cadmium fumes and dust has been reported to result in emphysema, hypertension, kidney failure, osteomalacia, and perhaps an increased incidence of cancer. To help maintain the balance between supply and demand for cadmium, efforts can be made to recycle such cadmium‐containing materials as spent nickel‐cadmium batteries as well as dust and other residues from the pigment industry. Consumption of cadmium is in batteries, coating and plating, pigments, plastics and synthetic products, and alloys and other uses. Cadmium is an important component in brazing and low melting alloys, used in bearings, solders, and nuclear reactor control rods.
Cadmium Compounds
Authors: Herron Norman 
Published: July 2004

Abstract
Naturally occurring cadmium compounds are limited to the rare minerals, greenockite, CdS, and otavite, an oxycarbonate, but neither is an economically important source of cadmium metal or its compounds. Instead, cadmium compounds are usually derived from metallic cadmium produced as a by‐product of lead‐zinc smelting or electrolysis. In general, cadmium compounds exhibit properties similar to the corresponding zinc compounds. The principal areas of cadmium usage in terms of U.S. consumption in 2001 were batteries, 75%; pigments, 12%; coatings and plating, 8%; plastic stabilizers, 4%; and nonferrous alloys and other uses, 1%. Cadmium hydroxide is the anode material of Ag–Cd and Ni–Cd rechargeable storage batteries. Cadmium sulfide, selenide, and especially telluride find utility in solar cells. In flexible PVC, cadmium salts such as stearate are used as heat and light stabilizers. Cadmium cyanide, acetate, fluoroborate, or sulfate is used as an electrolyte in electroplating onto other metals, imparting corrosion protection. The cadmium chalcogenide semiconductors have found numerous applications ranging from rectifiers to photoconductive detectors in smoke alarms. Many Cd compounds are used as phosphors in luminescent screens. The declining use of cadmium in plastics and as pigments in the 1980s, largely because of health and environmental concerns and the concomitant introduction of Cd substitutes, has been offset by its increased use in rechargeable storage (Ni–Cd) batteries. Continued and growing concern over the toxicity of cadmium in the environment is expected to lead to alternatives for cadmium compounds in all applications. Inorganic compounds include cadmium arsenides, antimonides, and phosphides; cadmium borates; cadmium carbonate; cadmium complexes; cadmium halides; cadmium hydroxide; cadmium nitrate; cadmium oxide; cadmium phosphates; and others. Many organocadmium compounds are known but few have been of commercial importance. They include dialkyl cadmium compounds, cadmium acetate, and organocadmium soaps.
Calcium Carbide
Authors: Cameron William L. 
Published: July 2004

Abstract

Chemically pure calcium carbide, Ca
2
C, is a colorless solid; however, the pure material can be prepared only by very special techniques. China is the world's largest producer of calcium carbide. Commercial calcium carbide is composed of calcium carbide, calcium oxide, CaO, and other impurities present in the raw materials. Industrial‐grade calcium carbide contains about 80% as CaC
2
, 15% CaO, and 5% other impurities. In the United States calcium carbide‐based acetylene is mainly used in the oxyacetylene welding market, although some continues to be used for production of such chemicals as vinyl ethers and acetylenic alcohols. Calcium carbide is used extensively as a desulfurizing reagent in steel and ductile iron production, allowing steel mills to use high sulfur coke. The exothermic reaction of calcium carbide and water‐yielding acetylene forms the basis of the most important industrial use of calcium carbide. An important use of calcium carbide has developed in the iron and steel industries, where the carbide has been found to be an effective desulfurizing agent for blast‐furnace iron. Calcium carbide is produced commercially by reaction of high purity quicklime and a reducing agent such as coke in an electric furnace at 2000–2200°C. Commercial calcium carbide, containing about 80% CaC
2
, is formed in the liquid state. The liquid calcium carbide is tapped from the furnace into cooling molds. Calcium carbide is classed as a hazardous chemical under U.S. Department of Transportation regulations. Domestic shipments are mainly in steel tote bins. Containers must be marked “Flammable solid, dangerous when wet” and have the United Nations designation UN 1402. Although acetylene is considered to be a material having a very low toxicity, a threshold limit value (TLV) of 2500 ppm has been established by NIOSH. In the presence of a small amount of water carbide may become incandescent and ignition of the evolved air–acetylene mixture may occur. Nonsparking tools should be used when working in the area of acetylene‐generating equipment.
Calcium and Calcium Alloys
Authors: Vrana Lisa M. 
Published: July 2004

Abstract

Calcium, Ca, a member of Group 2 (IIA) of the Periodic Table between magnesium and strontium, is classified, together with barium and strontium, as an alkaline‐earth metal and is the lightest of the three. Calcium metal does not occur free in nature; however, in the form of numerous compounds, it is the fifth most abundant element, constituting 3.63% of the earth's crust. Calcium is mainly used for improvement of steel; as a reducing agent for many reactive, less common metals; to remove bismuth from lead; as a desulfurizer and deoxidizer for ferrous metals and alloys; as an alloying agent for aluminum, silicon, and lead in the manufacture of lead–acid batteries and for permanent magnet manufacture. Pure calcium is a bright, silvery‐white metal, although under normal atmospheric conditions, freshly exposed surfaces of calcium quickly become covered with an oxide layer. The metal is extremely soft and ductile. Calcium's usefulness as a structural material is limited by low tensile strength and high chemical reactivity. Calcium has a valence electron configuration of 4
s
2
and characteristically forms divalent compounds. It is very reactive and reacts vigorously with water, liberating hydrogen and forming calcium hydroxide, Ca(OH)
2
. Calcium does not readily oxidize in dry air at room temperature but is quickly oxidized in moist air or in dry oxygen at about 300°C. Calcium reacts with fluorine at room temperature and with the other halogens at 400°C. Calcium is an excellent reducing agent and is widely used for this purpose. Although in Western countries the aluminothermic process has completely replaced the electrolytic method, electrolysis is believed to be the method used for calcium production in the People's Republic of China and the Commonwealth of Independent States (CIS). Because of its extreme chemical reactivity, calcium metal must be carefully packaged for shipment and storage. The metal is packaged in sealed argon‐filled containers. Calcium is classed as a flammable solid and is nonmailable. Calcium metal and most calcium compounds are nontoxic. Care must be taken, however, to avoid contact with water owing to the exothermic liberation of hydrogen and the resulting explosion hazard. Direct alloying of the pure metals is normally used in the production of 80% calcium–magnesium, 70% magnesium–calcium, and 75% calcium–aluminum alloys.
Aluminum Oxide (Alumina), Calcined, Tabular, and Aluminate Cements
Authors: MacZura George 
Published: July 2004

Abstract

Calcined aluminas are generally obtained from Bayer process gibbsite
α
‐Al(OH)
3
, thermal decomposition of which follows the transition through the generic gamma alumina phases to
α
‐alumina (corundum),
α
‐Al
2
O
3
. Calcination of gibbsite has been done in rotary kilns for many years. Specialty calcined aluminas can also be prepared in stationary or fluid bed calciners. Most ceramic grade aluminas are supplied dry ground to about 95%

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(44
µ
m) using 85–90% Al
2
O
3
ceramic ball, attrition, vibro‐energy, or fluid‐energy milling. More fully ground, or superground, calcined aluminas having particle size distributions that approximate the natural or ultimate crystal size of the Bayer grain as calcined are often desired. Thermally reactive aluminas contain submicrometer crystals. These must be separated from the Bayer agglomerate during grinding to permit dense compaction upon ceramic forming, and thus, enhance densification upon sintering at lower temperatures. Process control techniques permit production of calcined specialty aluminas having controlled median particle sizes differentiated by about 0.5
µ
m. This broad selection enables closer shrinkage control of high tech ceramic parts. Tabular alumina is a high density, high strength form of
α
‐Al
2
O
3
made by sintering an agglomerated shape of ground, calcined alumina. It is available in the form of smooth balls which are crushed, screened, and ground to obtain a wide variety of graded, granular, and powdered products. Tabular alumina is the ideal base material for high alumina brick, and monolith liners in the metal, ceramic, and petrochemical industries. Other applications include their use in electrical insulators, electronic components, and kiln furniture. High purity calcium aluminate cements (CAC) are primarily used as binders for high strength refractory castables to form linings up to about 1.0 m thick, as in iron blast furnaces. The high purity CAC finds extensive use as an efficient binder for other aggregates such as fire clays, kaolin, andalusite, kyanite, pyrophyllite, sillimanite, mullite, and refractory‐grade bauxite. The many applications cited for tabular alumina in refractories are also common for high purity CAC.
Calcium Chloride
Authors: Vrana Lisa M. 
Published: July 2004

Abstract

Calcium chloride, CaCl
2
, is a white, crystalline salt that is very soluble in water. Solutions containing 30–45 wt % CaCl
2
are used commercially. Of the alkaline‐earth chlorides it is the most soluble in water. It is extremely hygroscopic and liberates large amounts of heat during water absorption and on dissolution. It forms a series of hydrates containing one, two, four, and six moles of water per mole of calcium chloride. Commercial applications of calcium chloride and its hydrates exploit one or more of its properties with regard to aqueous solubility, hygroscopic nature, and the heat gained or lost when one hydrated phase changes to another. Because of its high solubility in water, calcium chloride is used to obtain solutions having relatively high densities. Viscosity is an important property of calcium chloride solutions in terms of engineering design and in application of such solutions to flow‐through porous media. In the United States the principal route for making calcium chloride is by the evaporation of underground brines. Significant markets in the United States are for deicing during the winter, and roadbed stabilization, and as a dust palliative during the summer. Use as an accelerator in the ready‐mix concrete industry is sizable, but there is concern about the possible corrosion of steel in, highways and buildings. Calcium chloride is also used in oil and gas well drilling. Food‐grade calcium chloride is used in cheese making to aid in rennet coagulation and to replace calcium lost in pasteurization. In the canning industry it is used to firm the skin of fruit such as tomatoes, cucumbers, and jalapenos. Food‐grade calcium chloride is used in the brewing industry as a basic component of certain beers. Calcium Chloride is not considered to be harmful to the environment. Above certain levels chloride is toxic to plants and animals.
Caprolactam
Authors: L. Crescentini William B. Fisher 
Published: July 2004

Abstract

Caprolactam (2‐oxohexamethylenimine, hexahydro‐2
H
‐azepin‐2‐one) is one of the most widely used chemical intermediates. However, almost all of the annual production of

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is consumed as the monomer for nylon‐6 fibers and plastics. Cyclohexanone, which is the most common organic precursor of caprolactam, is made from benzene by either phenol hydrogenation or cyclohexane oxidation. Caprolactam is a white, hygroscopic, crystalline solid at ambient temperature, with a characteristic odor. It is very soluble in water and in most common organic solvents and is sparingly soluble in high molecular weight aliphatic hydrocarbons. Molten caprolactam is a powerful solvent for polar and nonpolar organic chemicals. The low melting point of caprolactam and its stability and low viscosity form the basis for commercial transportation as a liquid in insulated tank cars or trucks. Caprolactam is an amide and therefore undergoes the reactions of this class of compounds. It can be hydrolyzed,
N
‐alkylated,
O
‐alkylated, nitrosated, halogenated, and subjected to many other reactions. All commercial processes for the manufacture of caprolactam are based on either toluene or benzene, each of which occurs in refinery BTX‐extract streams. Alkylation of benzene with propylene yields cumene, a source of phenol; ca 10% of U.S. phenol is converted to caprolactam. Worldwide caprolactam demand increased by about 2% per year during the 1980s, and similar growth is expected into the 1990s. DSM America produces caprolactam only for merchant sales, both domestic and foreign. BASF is a customer, following acquisition of Enka's U.S. fiber and plastics plants, and also a captive producer of caprolactam. Allied‐Signal's production is primarily captive for nylon‐6 fibers and plastics, but substantial amounts are supplied to the export market. Caprolactam has a low order of toxicity. It presents no appreciable health hazard if it is handled properly. Prolonged exposure to dust or vapors causes irritation of eyes, mucous membranes, and skin; inhalation may cause irritation of the respiratory tissues. Skin contact, if prolonged, can lead to dermatosis. A thorough wash with water, in which caprolactam is very soluble, or with soap and water, normally is sufficient to remove caprolactam from contaminated parts of the body. Caprolactam has been extensively tested for its mutagenic potential. Based on the overall weight of evidence, caprolactam would be considered nonmutagenic.
Chloroformates and Carbonates
Authors: Kreutzberger Charles B. 
Published: July 2004

AbstractThe chemistry of carbonic and carbonochloridic esters, commonly referred to as chloroformates and carbonates, is reviewed. These materials are highly reactive with a variety of functional groups and lead to synthetic intermediates for use in pesticides, perfumes, drugs, polymers, dyes, and fuel additives. This article emphasizes the commercial aspects of the carbonate and chloroformate chemistry, including physical and chemical properties, manufacturing processes, analytical test methods, health and effects, environmental aspects, storage, transportation, and uses.
Carbon Tetrachloride
Authors: Holbrook Michael T. 
Published: July 2004

Abstract

Carbon tetrachloride at ordinary temperature and pressure is a heavy, colorless liquid with a characteristic nonirritant odor. It was one of the first organic chemicals produced on a large scale. It is produced in the United States by either the total chlorination of various hydrocarbons or chlorinated hydrocarbons, or by the chlorination of carbon disulfide. U.S. capacity has been estimated at about 273,000 t/yr. Production can be varied in favor of more coproduct perchloroethylene. Projected growth rates of

, per year are probably overstated and actual production will probably fall even faster. The primary use of carbon tetrachloride, CFC‐11 and CFC‐12, will be banned by the Montreal Protocol by the year 2000. Carbon tetrachloride is regulated under a number o ederal and state laws.
Coal Conversion Processes, Carbonization
Authors: Kaegi Dennis , Addes Valery , Valia Hardarshan , Grant Michael 
Published: July 2004

AbstractCarbonization of coal entails heating coal to high temperatures in the absence of oxygen to distill out tars and light oils. This process is used to produce metallurgical coke for use in iron making blast furnaces and other smelting processes. A gaseous by‐product referred to as coke oven gas or coal gas is also formed along with ammonia, water, and sulfur compounds. Coke over gas is a valuable heating fuel. Other carbonization by‐products are usually refined within the coke plant to produce commodity chemicals.Coking coals and the various coal constituents that lead to the production of high quality cokes are described. The carbonization process, including the coking mechanism and design of coke ovens, is discussed as are coke properties and coke uses.
Carbon Dioxide
Authors: Pierantozzi Ronald 
Published: July 2004

AbstractCarbon dioxide is valuable as a chemical intermediate, a liquid refrigerant, and a source of inert gas. It is produced from natural gas wells, lime‐kiln operations, and several other important processes. Most of the significant industrial processes for the production of CO2are reviewed in this article. Methods of purification include reaction and potassium permanganate, reaction with potassium dichromate, adsorption using activated carbon, liquefaction, and solidification. Numerous uses including food freezing, enhanced oil recovery, chemical manufacturing, refrigeration, and carbonation are reviewed.
Carbon Monoxide
Authors: George Christine 
Published: July 2004

AbstractCarbon monoxide, gaseous in normal atmospheric conditions, is colorless, odorless, and highly toxic. Carbon monoxide is a co‐product, along with hydrogen, in synthetic gas (syngas) production. Several technologies are used to produce syngas and these are discussed. Gas pipeline is a cost‐effective way to manufacture and deliver carbon monoxide to the user. Industrially produced carbon monoxide is used in the chemical industry for the synthesis of several compounds, such as acetic acid, polycarbonates, acetic anhydride, polyketones, etc. The demand for carbon monoxide as a raw material for chemical synthesis is expected to continue. Carbon monoxide is also a by‐product of highway vehicle exhaust. Other sources are from industrial emissions and fuel combustion. Hazards associated with carbon monoxide use derive from its toxicity and flammability.
Carbon Disulfide
Authors: Smith David E. , Timmerman Robert W. 
Published: July 2004

AbstractCarbon disulfide, CS2, is a highly volatile, flammable, clear, colorless, dense liquid that has many useful chemical and physical properties. An industrially important chemical for over one hundred years, most carbon disulfide is now produced by reaction of hydrocarbon gas with sulfur in a process developed in the 1950s, although many small capacity plants still employ a retort or electric furnace route based on wood charcoal and sulfur. Modern plants achieve a 99.99% pure carbon disulfide product by means of fractional distillation. Most of carbon disulfide produced worldwide goes into manufacturing viscose rayon and cellophane film. Carbon disulfide is also used in manufacturing numerous organic sulfur compounds for a variety of applications including rubber vulcanization accelerators, flotation chemicals, pharmaceutical intermediates, fungicides, and insecticides. The carbon disulfide process route to carbon tetrachloride was discontinued in the United States during 1991 because of environment pressures on the end product. Carbon disulfide is very toxic, and the U.S. Government limits the 8‐h time‐weighted average exposure to 4 ppm maximum (12 mg/m3) in air. Health and environmental concerns related to carbon disulfide have curtailed some uses, such as in grain fumigants and solvents. Special precautions must be exercised in handling carbon disulfide because of its toxicity, high volatility, wide flammability range, and low ignition temperature.