Sources in coal

Ammonia (NH3) Aerobic biological source in Coal and fuel oil combustion ... 

The element is commercially obtained from the dusts of smelters processing zinc ores, as well as recovered from combustion by-products of certain coals. A large reserve of the elements for future uses in insured in coal sources. 

Coal is used ia industry both as a fuel and ia much lower volume as a source of chemicals. In this respect it is like petroleum and natural gas whose consumption also is heavily dominated by fuel use. Coal was once the principal feedstock for chemical production, but ia the 1950s it became more economical to obtain most industrial chemicals from petroleum and gas. Nevertheless, certain chemicals continue to be obtained from coal by traditional routes, and an interest in coal-based chemicals has been maintained in academic and industrial research laboratories. Much of the recent activity in coal conversion has been focused on production of synthetic fuels, but significant progress also has been made on use of coal as a chemical feedstock (see Coal CONVERSION processes). 

Environmental considerations also were reflected in coal production and consumption statistics, including regional production patterns and economic sector utilization characteristics. Average coal sulfur content, as produced, declined from 2.3% in 1973 to 1.6% in 1980 and 1.3% in 1990. Coal ash content declined similarly, from 13.1% in 1973 to 11.1% in 1980 and 9.9% in 1990. These numbers clearly reflect a trend toward utilization of coal that produces less SO2 and less flyash to capture. Emissions from coal in the 1990s were 14 x 10 t /yr of SO2 and 450 x 10 t /yr of particulates generated by coal combustion at electric utiUties. The total coal combustion emissions from all sources were only slightly higher than the emissions from electric utiUty coal utilization (6). 

The MTG process was developed for synfuel production in response to the 1973 oil crisis and the steep rise in crude prices that followed. Because methanol can be made from any gasiftable carbonaceous source, including coal, natural gas, and biomass, the MTG process provided a new alternative to petroleum for Hquid fuels production. New Zealand, heavily dependent on foreign oil imports, utilizes the MTG process to convert vast offshore reserves of natural gas to gasoline (59). 

There are, however, a variety of other sources of methane that have been considered for fuel supply. Eor example, methane present in coal (qv) deposits and formed during mining operations can form explosive mixtures known as fire damp. In Western Europe, some methane has been recovered by suction from bore holes drilled in coal beds and the U.S. Bureau of Mines has tested the economic practicaUty of such a system. Removal of methane prior to mining the coal would reduce explosion ha2ards associated with coal removal. As much as 11.3 x 10 (400 trillion (10 ) cubic feet or 400 TCE) of... 

Industrial Wastewater Treatment. Industrial wastewaters require different treatments depending on their sources. Plating waste contains toxic metals that are precipitated and insolubiHzed with lime (see Electroplating). Iron and other heavy metals are also precipitated from waste-pidde Hquor, which requires acid neutralization. Akin to pickle Hquor is the concentrated sulfuric acid waste, high in iron, that accumulates in smokeless powder ordinance and chemical plants. Lime is also useful in clarifying wastes from textile dyeworks and paper pulp mills and a wide variety of other wastes. Effluents from active and abandoned coal mines also have a high sulfuric acid and iron oxide content because of the presence of pyrite in coal. 

Historical. Pyridines were first isolated by destructive distillation of animal bones in the mid-nineteenth century (2). A more plentifiil source was found in coal tar, the condensate from coking ovens, which served the steel industry. Coal tar contains roughly 0.01% pyridine bases by weight. Although present in minute quantities, any basic organics can be easily extracted as an acid-soluble fraction in water and separated from the acid-insoluble tar. The acidic, aqueous phase can then be neutrali2ed with base to Hberate the pyridines, and distilled into separate compounds. Only a small percentage of worldwide production of pyridine bases can be accounted for by isolation from coal tar. Almost all pyridine bases are made by synthesis. 

Charcoal briquet production from all sources in-cluding wood, bark, lignite, coal, and agricultural residue. 

Until 1960, coal was the source material for almost all benzene produced in Europe. Petroleum benzene was first produced in Europe by the United Kingdom in 1952, by Erance in 1958, by the Eederal Republic of Germany in 1961, and by Italy in 1962. Coal has continued to decline as a benzene source in Europe, and this is evident with the closure of coke ovens in Germany (73). Most of the benzene produced in Europe is now derived from petroleum or pyrolysis gasoline. In Europe, pyrolysis gasoline is a popular source of benzene because European steam crackers mn on heavier feedstocks than those in the United States (73). 

A further source of C9 material is coal tar. Structures of the two resins precursors are roughly similar, except the presence of small quantities of coumarone in coal tar feedstream. There is a significant difference in the concentrations of individual monomers coal-tar-based raw material is richer in indene (styrene/indene ratio =1 7) than the petroleum-based feedstream (styrene/indene ratio =1 1). 

Venmri scrubbers have been applied to control PM emissions from utility, industrial, commercial, and institutional boilers fired with coal, oil, wood, and liquid waste. They have also been applied to control emission sources in the chemical, mineral products, wood, pulp and paper, rock products, and asphalt manufacrnring industries lead, aluminum, iron and steel, and gray iron production industries and to municipal solid waste incinerators. Typically, venturi scrubbers are applied where it is necessary to obtain high collection efficiencies for fine PM. Thus, they are applicable to controlling emission sources with high concentrations of submicron PM. 

The main sources of hydrogen in modern aimnoma plants arc coal, petroleum fractions, and natural gas, witli the latter being die principal source in... 

Throughout the industrialized world over the past two centuries, coal became relied upon as an energy source for industrial processes and for residential heat. In the United States, all the coal consumed before the year 1800—much of it imported from Britain—amounted to only 108,000 tons, which is one ten-thousandth of current annual U.S. production. Until 1840, wood exceeded coal as an energy source. However, coal then began a slow, steady expansion in usage, and, for over a century, until 1951, it was the chief energy source in the United States, contributing in the area of transportation (railroads) as well as the earlier, familiar sectors of industrial processes and residential heat. 

Since the early 1990s the United States has imported more oil than it has produced for its own use. And, as the nuclear option became frozen, coal has become the chief source for gcirerating electricity, which itself accounts for about 35 percent of the energy sector. In 1997, 52 percent of electricity produced in the United States was generated from coal and in other recent years the fraction has approached 56 percent. Since the United States accounts for one—quarter of total world energy usage, the increase in coal use in the United States alone has a significant... 

Resource pessimists counter that this process cannot proceed forever because the eternal persistence of demand for any given commodity that is destroyed by use must inevitably lead to its depletion. I lowever, the eternal persistence assumption is not necessarily correct. The life of a solar system apparently is long but finite. Energy sources such as nuclear fusion and solar energy in time could replace more limited resources such as oil and natural gas. Already, oil, gas, nuclear power, and coal from better sources have displaced traditional sources of coal in, for example, Britain, Germany, Japan, and France. 

United States and the world (Figure 1), despite perceptions that it has been replaced by other sources. In 1997 production ofboth coal (23.2 quadrillion Btus, or about 4.6 billion barrels of oil) and natural gas (19.5 quadrillion Btus, or about 3.9 billion barrels of oil) on an energy equivalent basis exceeded U.S. domestic oil production (13.6 quadrillion Btus, equivalent to about 2.7 billion barrels, or 3.1 billion barrels of oil if natural gas liquids are included). Coal production in the United States nearly doubled from 1970 to 2000 (from about 600 million tons to about 1 billion tons produced annually). Meanwhile, petroleum consumption at 18.6 million barrels of oil per day is near the all-time high of 18.8 million barrels of oil per day in 1978. Net U.S. petroleum imports (8.9 million barrels of oil per day) in 1997 were worth 67 billion and exceeded U.S. petroleum production (8.3 million... 

Natural gas will continue to be substituted for oil and coal as primary energy source in order to reduce emissions of noxious combustion products particulates (soot), unburned hydrocarbons, dioxins, sulfur and nitrogen oxides (sources of acid rain and snow), and toxic carbon monoxide, as well as carbon dioxide, which is believed to be the chief greenhouse gas responsible for global warming. Policy implemented to curtail carbon emissions based on the perceived threat could dramatically accelerate the switch to natural gas. 

Excise taxes placed on specific energy sources tend to reduce the demand for these energy sources in both the short and the long run. The federal government imposes excise taxes on almost all petroleum products and coal (see Table I). The federal government also imposes excise taxes on many transportation uses of methanol, ethanol, natural gas, and propane and imposes a fee on electricity produced from nuclear power plants. 

About eight gallons of coal tar are obtained from a ton of coal. Coal tars are very complex mixtures over 200 different carbon compounds have been isolated from them. While the great value of coal to mankind has been as a fuel, a source of energy, the many substances in coal gas and coal tar make coal also an important source of chemical raw materials. 

One of the most studied of the polyaromatic hydro-carbone (PAH) is benzo(a)pyrene (BaP), which is present in coal tar at coke oven plants. The BaP content of coal tar is between 0.1% and 1 % and it contributes to the serious potential health effects on employees exposed to coke oven emissions. The largest sources of BaP are open burning and home heating with wood and coal. The latter alone contributes 40 percent of all the BaP released each year in the USA. 

History. Interest in sites containing PAHs that antedate the introduction of modern synthetic chemicals. Gas works and the prodnction of tar residues are common in conntries that used coal as a source of coal gas for lighting and heating. Many of these sites have now been abandoned since the industry has been replaced by the dominance of electricity and oil. 

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