Coal, vanadium

In the United States, the largest concentration of atmospheric vanadium occurs over Eastern seaboard cities where residual fuels of high vanadium content from Venezuela are burned ia utility boilers. Coal ash ia the atmosphere also coataias vanadium (36). Ambient air samples from New York and Boston contain as much as 600—1300 ng V/m, whereas air samples from Los Angeles and Honolulu contained 1—12 ng V/m. Adverse pubHc health effects attributable to vanadium ia the ambieat air have aot beea deteroiiaed. lacreased emphasis by iadustry oa controlling all plant emissions may have resulted ia more internal reclamation and recycle of vanadium catalysts. An apparent drop ia consumption of vanadium chemicals ia the United States since 1974 may be attributed, in part, to such reclamation activities. 

Contaminants in fuels, especially alkali-metal ions, vanadium, and sulfur compounds, tend to react in the combustion zone to form molten fluxes which dissolve the protective oxide film on stainless steels, allowing oxidation to proceed at a rapid rate. This problem is becoming more common as the high cost and short supply of natural gas and distillate fuel oils force increased usage of residual fuel oils and coal. 

Hazardous air pollutants (HAPs) are substances that may cause immediate or long-term adverse effects on human health. HAPs can be gases, particulates, trace metals such as mercui y, and vapors such as benzene. For coal-fired power plants, the HAPs of most concern are metals such as mercury, arsenic, and vanadium. 

One of the more important considerations in determining the end use of synthetic graphite is its contamination with metallic components Metals such as iron, vanadium, and especially in nuclear applications, boron are deleterious to the performance of graphite Table 3 presented the extraction yields of NMP-soluble material for three bituminous coals. For these coals, mineral matter and insoluble coal residue were separated from the extract by simple filtration through 1-2 pm filter paper fable 13 lists the high-temperature ash content in the dry coal, and in their corresponding NMP-insoluble and NMP-soluble products. The reduced ash content of the extract is typically between 0.1 to 0.3 wt% using traditional filtration techniques for the small-scaled extraction experiments... 

Stretford A process for removing hydrogen sulfide and organic sulfur compounds from coal gas and general refinery streams by air oxidation to elementary sulfur, using a cyclic process involving an aqueous solution of a vanadium catalyst and anthraquinone disulfonic acid. Developed in the late 1950s by the North West Gas Board (later British Gas) and the Clayton Aniline Company, in Stretford, near Manchester. It is the principle process used today, with over 150 plants licensed in Western countries and at least 100 in China. 

Anthraquinone itself is traditionally available from the anthracene of coal tar by oxidation, often with chromic acid or nitric acid a more modern alternative method is that of air oxidation using vanadium(V) oxide as catalyst. Anthraquinone is also produced in the reaction of benzene with benzene-1,2-dicarboxylic anhydride (6.4 phthalic anhydride) using a Lewis acid catalyst, typically aluminium chloride. This Friedel-Crafts acylation gives o-benzoylbenzoic acid (6.5) which undergoes cyclodehydration when heated in concentrated sulphuric acid (Scheme 6.2). Phthalic anhydride is readily available from naphthalene or from 1,2-dimethylbenzene (o-xylene) by catalytic air oxidation. 

In the gasifiers the sulphur present in the coal is converted to H S which is scrubbed out, together with the C0 in the downstre Rectisol unit. The effluent stream from this unit (typically 1.5 % HpS in CO2) is treated in a homogeneous catalytic process in which tne H S is converted to high grade elemental sulphur. The catalytic liquor consists essentially of an alkaline vanadium solution. In the... 

The modern investigations of trace elements in coals were pioneered by Goldschmidt, who developed the technique of quantitative chemical analysis by optical emission spectroscopy and applied it to coal ash. In these earliest works, Goldschmidt (31) was concerned with the chemical combinations of the trace elements in coals. In addition to identifying trace elements in inorganic combinations with the minerals in coal, he postulated the presence of metal organic complexes and attributed the observed concentrations of vanadium, molybdenum, and nickel to the presence of such complexes in coal. 

Horton and Aubrey (34) handpicked pure vitrain samples from coals and separated them into five different specific gravity fractions. They then analyzed these for 16 minor elements. They concluded that for the three vitrains they studied, beryllium, germanium, vanadium, titanium, and boron were contributed almost entirely by the inherent (organically combined) mineral matter and that manganese, phosphorus, and tin were associated with the adventitious (inorganically combined) mineral matter. 

Approximate contents of 14 minor and trace elements in oils produced from three coals by the catalytic hydrogenation process of Gulf Research and Development Co. were determined by emission spectroscopy. The results were compared with corresponding data for the original coals and the solid residues from the process. The contents of ash, sulfur, vanadium, lead, and copper are near or below the limits specified for an oil to be fired directly in a gas turbine while sodium and probably calcium are too high. Titanium appears to be somewhat enriched in the oils analyzed relative to other elements, suggesting its presence in organo-metallic complexes. 

In an analysis of airborne coal fly ash, Natusch and co-workers (50) found that 12 elements, i.e., Pb, Tl, Sb, Cd, Se, Zn, As, Ni, Cr, S, Be, and Mn, were concentrated in the smallest diameter particles. Mercury, although not studied, was expected to follow suit because of its high volatility and probable deposition on small particles. Toca and Berry reported similar findings for lead and cadmium (5). Atmospheric vanadium (59, 60) as well as selenium, antimony, and zinc (61) arising principally from residual fuel combustion also showed a similar pattern. The health risk of this concentration phenomenon is enhanced because of the magnitude of fine particulate emissions and the ease with which these particles bypass particle collection devices, resist fallout, and readily disseminate (50). 

Jhe distribution of beryllium, boron, titanium, vanadium, chromium, cobalt, nickel, copper, zinc, gallium, germanium, tin, molybdenum, yttrium, and lanthanum in the principal coal-producing beds of the Interior Province has been studied by the U. S. Geological Survey. Data, methods of sampling, and analyses are discussed by Zubovic and others (II, 12). This chapter discusses the occurrence of 13 of these elements with respect to geological and geochemical environments of coal deposition and chemical properties of the elements. Zinc and tin are not included in this study because they were detected in only a few samples. 

The samples of the Eastern Interior Region considered here are those shown in Figure 1 west of the dashed north-south line in Illinois. All these samples are from Illinois beds 5 and 6. This selection was made to obtain a series of samples located at increasing distances from the source area of the sediments. Because the sedimentary source for the Indiana and Kentucky coal areas are less certainly known (6), the samples from those areas are not considered here. Except for beryllium and vanadium, the minor element content of samples from those areas is comparable to samples from western Illinois. The beryllium content of all these coals was reported by Stadnichenko and others (8). The unusually high vanadium content of some of the southern coals of the Eastern Interior Region is discussed below. 

Vanadium-Rich Coals in the Eastern Interior Region... 

Figure 10 graphically shows data for the columnar samples of coal bed 5 of Illinois and its correlative in Indiana and Kentucky. The thicknesses of the beds at the localities sampled and of the top (block 1), the adjacent blocks, and the bottom blocks are also shown. The sizes of the blocks of the central portions of the columns are not shown. Data for vanadium, chromium, and nickel from these sections of the bed are shown in Table II. Samples 1-12 contain normal amounts of vanadium samples 13-19 contain large amounts of vanadium in the top part. 

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