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Über dieses Buch

This text of applied chemistry considers the interface between chemistry and chemical engineering, using examples of some of the important process in­ dustries. Integrated with this is detailed consideration of measures which may be taken for avoidance or control of potential emissions. This new emphasis in applied chemistry has been developed through eight years of experience gained from working in industry in research, development and environment­ al control fields, plus twelve years of teaching here using this approach. It is aimed primarily towards science and engineering students as well as to envi­ ronmentalists and practising professionals with responsibilities or an interest in this interface. By providing the appropriate process information back to back with emis­ sions and control data, the potential for process fine-tuning is improved for both raw material efficiency and emission control objectives. This approach also emphasizes integral process changes rather than add-on units for emis­ sion control. Add-on units have their place, when rapid action on an urgent emission problem is required, or when control simply is not feasible by pro­ cess integral changes alone. Obviously fundamental process changes for emission containment are best conceived at the design stage. However, at whatever stage process modifications are installed, this approach to control should appeal to the industrialist in particular, in that something more sub­ stantial than decreased emissions may be gained.

Inhaltsverzeichnis

Frontmatter

1. Background and Technical Aspects of the Chemical Industry

Abstract
The business niche occupied by the chemical industry is of primary importance to the developed world in its ability to provide components of all the food, clothing, transportation, accommodation, and employment enjoyed by modern man. Most material goods are either chemical in origin or have involved one or more chemicals during the course of their manufacture. In some cases the chemical interactions involved in the generation of final products are relatively simple ones. In others, for instance for the fabrication of some of the more complex petrochemicals and drugs, more complicated and lengthy procedures are involved. But by far the bulk of all modern chemical processing uses raw materials naturally occurring on or near the earth’s crust, as the raw materials for producing the commodities of interest.
M. B. Hocking

2. Air Quality and Emission Control

Abstract
In the early days of habitation of this planet, when the human population was small and its per capita consumption of energy was primarily as food (8,400–12,600 kJ/day; 2–3,000 kcal/day), total human demands on the biosphere were consequently small. Early requirements of goods were minimal and quite close to direct (requiring little fashioning) so that this early society’s total demands and wastes were easily accommodated and assimilable by the biosphere, with little impact.
M. B. Hocking

3. Water Quality and Emission Control

Abstract
Water is a vital commodity to industry for process feedstock (reacting raw material), solvent component and cooling purposes, as it is to us as individuals for all our personal water requirements. The global supply appears to be extensive, so much so that many people take it for granted. But when one considers that only 3% of this total resource exists as fresh water at any one time the concept of this as a globally limited and potentially exhaustible resource becomes more real (Table 3.1). When one further takes into account that roughly three quarters of this 3% is frozen from immediate use by the ice caps and glaciers of the world, then an appreciation of the limited extent of the available global fresh water becomes more apparent.
M. B. Hocking

4. Natural and Derived Sodium and Potassium Salts

Abstract
Sodium chloride, or common salt, is among the earliest chemical commodities produced by man, prompted, by its essential requirement in the diet and the scattered accessibility of available land- based supplies. The word salary itself is derived from the Roman “salarium”, which was a monetary payment given to soldiers for salt purchase to replace the original salt issue. While the initial production and harvesting of sodium chloride was from dietary interests, today this application represents less than 5% of the consumption, and uses as a chemical intermediate far exceed this (Table 4.1). The wide availability of sodium chloride has contributed to the derivation of nearly all com-pounds containing sodium or chlorine from this salt, and to the establishment of many large industrial chemical operations adjacent to major salt deposits. Three general methods are in common use for the recovery of sodium chloride, which in combination were employed for the world-wide production of 167 million tonnes of this commodity in 1976 and slightly less in 1981 (Table 4.2).
M. B. Hocking

5. Industrial Bases by Chemical Routes

Abstract
The dominant source of calcium carbonate is lime-stone, the most widely used of all rocks, but this occurs in nature with at least traces of clay, silica, and other minerals which may interfere with some applications. However, high calcium limestone consists of about 95% or better calcium carbonate. White marble, a metamorphosed form of pure limestone with a closely packed crystal structure, is chemically suitable. But marble is usually of higher value for other applications than as a chemical feedstock. Dolomitic limestones consist of calcium and magnesium carbonates present in a near one to one molar basis, though this ratio can vary widely in ordinary dolomites. For some applications at least, the presence of the magnesium carbonate is not a handicap to the use of this calcium base component of the dolomite. The remaining principal natural sources of calcium carbonate more closely reflect their biogenetic origin in the forms of chalk, which comprises the shells of microscopic marine organisms, bivalve shells, which for example are accessible in sufficient quantities on shores of the Gulf of Mexico to be employed as an industrial feedstock, and coral, which consists of the massive, sub-marine fused skeletons of multiple stationary organisms.
M. B. Hocking

6. Electrolytic Sodium Hydroxide and Chlorine and Related Commodities

Abstract
All electrolytic routes to sodium hydroxide and chlorine from sodium chloride brine have to contend with keeping the highly reactive products separated. Sodium and chlorine would react explosively together to return
$$ N{a^ + } + {e^ - } \to Na\,\left( {or\,NaOH + {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}{H_2}} \right) $$
(6.1)
$$ C{l^ - } - {e^ - } \to {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}C{l_2} $$
(6.2)
starting salt, and sodium hydroxide reacts vigrously with chlorine to give sodium chloride and sodium hypochlorite (Equations 6.3, 6.4), so that similar precautions are required with either sodium product. Two main procedures have
$$ 2Na + C{l_2} \to 2NaCl $$
(6.3)
$$ 2NaOH + C{l_2} \to NaCl + NaClO + {H_2}O $$
(6.4)
dominated the methods used to keep these products apart. One involves the separation of the electrochemical cell into two compartments by a porous vertical diaphragm which permits the needed passage of ions, but keeps the products separated.
M. B. Hocking

7. Sulfur and Sulfuric Acid

Abstract
Sulfur is widely distributed in the earth’s crust, but only to the extent of about 0.1% by weight. It is found here chiefly as the element, as sulfides, and as sulfates. The annual industrial mass of global sulfur production is about twice that of sodium hydroxide, another important commodity chemical, which is an indicator of the significance of sulfur in the chemical marketplace. However, in keeping with the varied geologic forms in which sulfur occurs and its non-uniform distribution in the crust, as well as the differences in the degree of industrialization of a country, there is considerable variation in the level of production, country by country (Table 7.1). The influence of these diverse factors is reflected in the per capita level of production of say Poland and Canada, which have market circumstances or natural factors which tend to make sulfur production advantageous and produce around 150 and 300 kg per capita per year. These annual per capita production figures are much higher than the 25 to 50 kg per capita per year experienced by Japan, the U.S.A., and the U.S.S.R., other large scale producers. Thus, the level of sulfur production of a country is markedly influenced by natural or market factors. However, the per capita sulfur consumption is generally a good indicator of the level of industrial activity of a country.
M. B. Hocking

8. Phosphorus and Phosphoric Acid

Abstract
Phosphorus occurrence in the lithosphere is predominantly as phosphates, PO4 3- with variations, although a rare iron-nickel phosphide, schreibersite ((Fe, Ni)3P)8 is also known in nature [1]. For this reason, phosphates are the primary source of elemental phosphorus for chemical process requirements. Only 0.20 to 0.27% phosphate (0.15 to 0.20% as P2O5; 0.07 to 0.09% as P) is present in ordinary crustal rocks, but nevertheless this is the location of the bulk of the phosphorus present in the lithosphere [2].
M. B. Hocking

9. Ammonia, Nitric Acid and their Derivatives

Abstract
Early samples of ammonia were obtained by such means as the bacterial action on the urea present in urine (Equation 9.1), or by the dry distillation
$$ H2N - CO - N{H_2} + {H_2}O\xrightarrow{{bacteria}}\,C{O_2} + 2N{H_3} $$
(9.1)
of protein-containing substances such as bone, horns, and hides. Small amounts were also obtained from the manufacture of coke or coal gas from coals. Ammonia is still recovered at the rate of 134,000 tonnes per year as an incidental part of U.S. coal-based operations [1,2], but this amounts to less than 1% of current U.S. ammonia production (Table 9.1). By far the bulk of ammonia produced today is by the direct combination of the elements. Other synthetic processes have been tested and found to be either impractical for commercial exploitation, or have gradually been supplanted by direct elemental combination for economic reasons.
M. B. Hocking

10. Aluminum and Compounds

Abstract
From its relatively small scale utilization of the order of 1/100th that of copper, lead, and zinc prior to 1900, to its present scale of production of three to five times that of these more traditional non-ferrous metals (Table 10.1), aluminum is a metal that has come of age in the twentieth century. Oersted, in Denmark, is credited with first obtaining impure aluminum in 1825, achieved by the reduction of aluminum chloride with potassium amalgam. Wöhler, two years later, obtained higher purity metal and more fully described its properties. Henri St.-C. Deville put aluminum production into commercial practice in France by 1845 using sodium fusion to reduce aluminum chloride (Equation 10.1).
M. B. Hocking

11. Ore Enrichment and Smelting of Copper

Abstract
Copper rivals gold as one of the oldest metals employed by man. Its first use about 10,000 years ago was stimulated by the natural occurrence of the metal in lumps or leaves in exposed rock formations, so called “native copper”. These exposures enabled the fashioning of simple tools directly by hammering and heat working of these fragments, and in so doing signalled the end of the Stone Age [1]. The natural occurrence of elemental copper is a feature of its relatively low standard reduction potential of +0.158 volts, significantly below hydrogen in the electromotive series and hence relatively easily accumulated in elemental form as a consequence of normal geologic processes. This contrasts with the much more easily oxidized aluminum, which lies above hydrogen in the electromotive series with a reduction potential of - 1.71 volts, and hence is never found in elemental form in nature.
M. B. Hocking

12. Production of Iron and Steel

Abstract
Iron, at 5 % of the earth’s crust, is the most abundant metal after aluminum and the fourth most abundant element present in the surface rocks of the earth [1]. Iron is also the pre-eminently useful metal of our society for the manufacture of machinery of all types and for constructional purposes. The general wide utility of iron, on its own quite a versatile metal, and of an increasingly wide variety of steels, iron alloys which are being tailored to meet a range of demanding applications, combine to make the tonnage of iron produced each year easily exceed the combined annual production of all the other metals used by man.
M. B. Hocking

13. Production of Pulp and Paper

Abstract
The production of wood pulp, and paper from this, is a primary industry in the sense of its utilization of a wood primary resource as its chief raw material, but it is also a secondary industry in the sense that it consumes large quantities of bulk inorganic chemicals such as chlorine, sodium hydroxide, pigments etc. produced by the primary chemical, or commodity chemical industry. In fact the pulp and paper business area alone consumes close to 10% of the inorganic chemicals produced in the countries in which it is a dominant industry, thus not only contributing directly to the employment and business activity in these areas, but also indirectly by its purchase from these primary areas of chemicals production.
M. B. Hocking

14. Fermentation Processes

Abstract
Strictly speaking, fermentation is the process of anaerobic breakdown or fragmentation of organic compounds by the metabolic processes of microorganisms. However, fermentation processes can be considered, in a more general way, to relate to the chemical changes of a substrate accomplished by selected micro-organisms or extracts of micro-organisms, to yield a useful product. This less specific definition includes micro-biological processes carried out under anaerobic (fermentative, or in the absence of air), aerobic (respiratory), and enzymatic (via extracts) conditions.
M. B. Hocking

15. Petroleum Production and Transport

Abstract
Early use of petroleum or mineral oil, as opposed to animal or plant oils, was by direct harvesting of the crude product from generally superficial surface seeps and springs. For example tar, obtained from the Pitch Lake (La Brea) area, Trinidad, has been used for the caulking of ships since the Middle Ages and is still marketed to the extent of about 142,000 tonnes per year [1, 2]. Tar from the Alberta tar sands was used in the 1700’s by Cree Indians of the Athabasca river area to seal their canoes, as recorded by Peter Pond. Also a thick bituminous gum was collected from the soil surface in the vicinity of the St. Clair River, Southern Ontario [3], and from Guanoco Lake, Venezuela [4], and these too were marketed for a range of purposes.
M. B. Hocking

16. Petroleum Refining

Abstract
It is commonly thought that crude oil from conventional oil wells is quite similar in composition, regardless of the source. This is not so. Both the physical characteristics and the composition vary widely, depending not only on the particular area of the world and the oil field from which it was obtained but also on the age, that is the number of years since production was initiated, in the oil field sampled.
M. B. Hocking

Backmatter

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