Economic importance

Water is a raw material which is available on Earth in unlimited quantities. Water is not consumed since, after use, it is fed back sooner or later into the Earth s water circulation. The local availability of water (e.g. in arid regions), especially with the purity necessary for the particular application, is another matter. Cheap high purity water is required for many applications. 

Statistics for the Federal Republic of Germany serve to illustrate the origin and production of water for an industrialized country. In 1991 a total of 6.1 - 10 m- of water was produced (corresponding to about 80 m per inhabitant) which comprises  

Water a raw material in principle available in unlimited quantities, since used water is fed back into the Earth s water circulation 

44- 10 m of water was extracted (= demand) in 1990 (of which ca. 84 % was surface water) which was mainly (ca. 70%) used as a coolant in power stations. The utilization of water is, however, slightly more than double this quantity, reflecting the multiple usage of the cooling water. 

In rain starved regions (southern Mediterranean, northern desert belt) potable water is produced on an industrial scale from sea- and brackish water using distillation plants (older technology), reverse osmosis (newer technology) and to a small extent electrodialysis plants (brackish water). 

Coating of substrates (particularly metallic substrates) with particulate plastics is a well-established technology. The fluidized-bed process was developed in 1952. The electrostatic powder coating technique introduced in 1965 has, however, made a substantially greater impact [3.46]. These two processes are discussed in Section 8.3.5. 

Thermosetting coating powders are applied mainly by electrostatic spraying and dominate the market. The annual growth rates worldwide are about 10%. Total 

In contrast to wet materials, almost no material is lost during application of coating powders (no solvents, no split-off products, powder overspray is recovered). These tonnages roughly correspond to two to three times the amount of ready-for-spraying, conventional industrial paint. 

Binder types Europe North America Far East 

Although other processes are described, thermosetting coating powders are produced exclusively by the extruder process. This method is employed because it is the cheapest and the most widely applicable and flexible it allows large plants to be supplied with material of consistent quality. Production with extruders includes the following steps  

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Natural gas analysis has considerable economic importance. In fact, commercial contracts increasingly specify not just volume but the calorific or heating value as well. Today the calorific value of a natural gas calculated from its composition obtained by chromatography is recognized as valid. There is therefore a large research effort devoted to increasing the precision of this analysis. 

The magnitude of the NHV has economic importance because the consumption and cost of motor fuels are frequently expressed in liters/100 km and in Francs/liter in France. From the technical viewpoint, the NHV, establishes the maximum range for a transport system with a given load. This is a decisive criterion for applications like aviation. 

A detailed study of the properties of the potential products is of prime technical and economic importance, because it allows the refiner to have a choice in selecting feedstocks for his different units for separation, transformation and conversion, to set their operating conditions, in order to satisfy the needs of the marketplace in the best ways possible. 

Materials that contain defects and impurities can exhibit some of the most scientifically interesting and economically important phenomena known. The nature of disorder in solids is a vast subject and so our discussion will necessarily be limited. The smallest degree of disorder that can be introduced into a perfect crystal is a point defect. Three common types of point defect are vacancies, interstitials and substitutionals. Vacancies form when an atom is missing from its expected lattice site. A common example is the Schottky defect, which is typically formed when one cation and one anion are removed from fhe bulk and placed on the surface. Schottky defects are common in the alkali halides. Interstitials are due to the presence of an atom in a location that is usually unoccupied. A... 

Caffeine. About 3% by weight of the roasted coffee bean is caffeine (16). The second U.S. Department of Agriculture world coffee crop estimate for 1988—1989 was 4.24 x 10 kg (93.3 million 100-lb bags) (102). World coffee consumption was predicted to rise in the foreseeable future at the rate of 1—2% per year and thus the total amount of caffeine and related alkaloids ingested from this source can also be expected to increase. Caffeine and related bases (eg, theophylline) are also found in various teas but, because most of the major producers (India, China, etc) export relatively Htfle of thek crops and keep most for domestic consumption, accurate figures on year-to-year production are more difficult to obtain. Nevertheless, these crops are of significant economic import (103). 

The examples given above represent only a few of the many demonstrated photochemical appHcations of lasers. To summarize the situation regarding laser photochemistry as of the early 1990s, it is an extremely versatile tool for research and diagnosis, providing information about reaction kinetics and the dynamics of chemical reactions. It remains difficult, however, to identify specific processes of practical economic importance in which lasers have been appHed in chemical processing. The widespread use of laser technology for chemical synthesis and the selective control of chemical reactions remains to be realized in the future. 

Steelmaking. Steelmaking is the most economically important slag refining process (see Steel). Pig iron contains up to 4% carbon, 1% manganese, 1%... 

The economic importance of an ore deposit itself is largely affected by mineral or metal prices. Mine closures and reopenings are a common event in the mineral iadustry for this reason. Economics can also be affected by the ore composition, for example, by unacceptable levels of penalty elements ia the ore. The assessment of overall economics of exploiting a given ore deposit is similar to that for any large-scale industry. The various cost components are those associated with equipment, labor, utiUties, contingencies, operation and production, transportation, working capital, suppHes, maintenance. 

Halogenation of nitromethane is utilized to produce two economically important pesticides, chloropicrin [76-06-2J, a soil fumigant, and bronopol, a biocide useful for control of microbial growth in cosmetics and industrial appHcations. 

Scrap that is unsuitable for recycling into products by the primary aluminum producers is used in the secondary aluminum industry for castings that have modest property requirements. Oxide formation and dross buildup are encountered in the secondary aluminum industry, and fluxes are employed to assist in the collection of dross and removal of inclusions and gas. Such fluxes are usually mixtures of sodium and potassium chlorides. Fumes and residues from these fluxes and treatment of dross are problems of environmental and economic importance, and efforts are made to reclaim both flux and metal values in the dross. 

Whereas issues of technician productivity, sample status, and scheduling of analyses are economically important, these take second place to the issue of measurement quaUty in the laboratory. LIMS software enables activities such as cahbration and proper maintenance to be scheduled automatically. By recording the results of these activities in the LIMS, the data to demonstrate proper performance are readily made available. Additionally, the schedule can be adjusted to reflect the actual needs of the individual instmments. 

Strontianite is the naturally occurring form of strontium carbonate. It has a theoretical strontium oxide content of 70.2%, but no economically workable deposits are known. There are some naturally occurring strontium—barium and strontium—calcium isomorphs, but none has economic importance. 

Oxygen-Cont iiningAmines. This group includes amine oxides, ethoxylated alkylamines, l-(2-hydroxyethyl)-2-imidazolines, and alkoxylates of ethylenediamine. Oxygen-containing amines are steadily increasing in economic importance. 

Uses ndReactions. a-Pinene (8) is useful for synthesizing a wide variety of terpenoids. Hydration to pine oil, acid-catalyzed isomerization to camphene, thermal isomerization to ocimene and aHoocimene, and polymerization to terpene resins are some of its direct uses. Manufacture of linalool, nerol, and geraniol has become an economically important use of a-pinene. 

D. B. McKeever and K. C. Jackson, "Economic Importance of the Timber Processing Industdes," ia R. W. Haynes, coordinator. An. Analysis of the Timber Situation in the United States, 1989—2040, General Technical Report RM-199, U.S. Department of Agriculture, Porest Service, Rocky Mountaia Porest and Range Experiment Station, Port Collins, Colo., 1990, Chapt. 4, pp. 59—78. 

A value of Ai/298 —199.2 8.4 kJ/mol (—47.61 2.0 kcal/mol) has been calculated for this reaction, which is of considerable economic importance to glass manufacturers because 2 3 during glass (qv) processing are gready increased by the presence of water. For this reason anhydrous borates or... 

Naturally occurring cadmium compounds are limited to the rare minerals, greenockite [1317-58 ] CdS, and otavite (1), an oxycarbonate, but neither is an economically important source of cadmium metal or its compounds. Instead, cadmium compounds are more usually derived from metallic cadmium [7440-43-9] which is produced as a by-product of lead—2inc smelting or electrolysis (see Cadmiumand cadmium alloys). Typically, this cadmium metal is burnt as a vapor, to produce the brown-black cadmium oxide [1306-19-0], CdO, which then acts as a convenient starting material for most of the economically important compounds. 

This article reviews the preparation, properties, characterization, use, economic importance, and future of some of the important synthetic copolymers. Polymer blends (qv) and composites (qv) are also mentioned. Biocopolymers are not included. 

The economic importance of copolymers can be cleady illustrated by a comparison of U.S. production of various homopolymer and copolymer elastomers and resins (102). Figure 5 shows the relative contribution of elastomeric copolymers (SBR, ethylene—propylene, nitrile mbber) and elastomeric homopolymers (polybutadiene, polyisoprene) to the total production of synthetic elastomers. Clearly, SBR, a random copolymer, constitutes the bulk of the entire U.S. production. Copolymers of ethylene and propylene, and nitrile mbber (a random copolymer of butadiene and acrylonitrile) are manufactured in smaller quantities. Nevertheless, the latter copolymers approach the volume of elastomeric butadiene homopolymers. 

Cyanohydrins are used primarily as intermediates in the production of other chemicals. Manufacture of methyl methacrylate, used to make acrylic mol ding resins and clear sheet, eg, Plexiglas acrylic sheet, from acetone cyanohydrin is the most economically important cyanohydrin process (see Methacrylic polymers). Cyanohydrins are also used as solvents in appHcations including fiber-spinning and metals refining. Cyanohydrins and derivatives reportedly act as antiknock agents in fuel oil and motor fuels and serve as electrolytes in electrolytic capacitors. 

Electronic coatings are of significant economic importance, as are the finished products in which they go. The worldwide total value of the resulting products is 500 biUion. Table 1 provides a geographic breakdown. The annual electronics coatings market value is estimated to be 5 biUion. These coatings are manufactured in several countries. Some of the principal manufacturers of electronic coatings are... 

Refrigera.tlon, In processes such as olefin separations, the economic importance of refrigeration exceeds that of the steam system. 

There has been a steady growth ia the economic importance of therapeutic ensymes, with sales reaching hundreds of millions of dollars per year as of 1992. Table 2 Hsts the trade names and costs of some of the more commonly prescribed enzyme preparations. Despite the magnitude of use of these products, the manufacture and sale of therapeutic enzymes represents a comparatively small fraction of the production and profits of the pharmaceutical houses that market them. 

Polymeric Membranes Economically important applications required membranes that could operate at higher pH than could CA, for which the optimum is around pH = 5. Many polymeric membranes are now available, most of which have excellent hydrolytic stabihty. Particularly prominent are polysulfone, polyvinyhdene fluoride, poly-ethersulfone, polyvinyl alcohol-polyethylene copolymers, and aciylic copolymers. 

Free-radical chain inhibitors are of considerable economic importance. The term antioxidant is commonly appUed to inhibitors that retard the free-radical chain oxidations, termed autoxidations, that can cause relatively rapid deterioration of many commercial materials derived from organic molecules, including foodstuffs, petroleum products, and plastics. The chain mechanism for autoxidation of hydrocarbons is ... 

Most abundant group of materials, composed of silicates of aluminium with sodium, potassium, calcium, and rarely barium. Most economically important mineral. Used for ceramics, glass, abrasive wheels, cements, insulation and fertilizer. 

Large-scale adhesive bonding of steel is of great interest to the automotive and appliance industries because of the opportunities it provides for design flexibility, weight savings, and manufacturing economy. Because of its economic importance. 

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