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Coal impurities

Serious pollution problems in some areas sources include mining, burning coal, impure sulfuric acid, insecticides, and herbicides. [Pg.485]

Bone coal impure coal that contains much clay or other fine-grained detrital mineral matter. [Pg.198]

Mineralized coal impure coal that is heavily impregnated with mineral matter, either dispersed or discretely localized along cleat joints or other fissures pyrite and calcareous minerals are the most common (ASTM D-2796). [Pg.198]

The following equilibrium is used to convert water and coal (impure carbon) to a (more convenient) gaseous fuel, called water gas. ... [Pg.485]

Arsenic Essential ultratrace element in red algae, chick, rat, pig, goat, and probably bumans. Deficiency results in depressed growth and increased mortality. Moderately toxic to plants, highly toxic to mammals. Serious pollution problems in some areas sources include mining, burning coal, impure sulfuric add, insecticides, and herbicides. [Pg.946]

Nature of Impurities in Coal. Impurities can be divided into two general classifications— inherent and removable. The inherent impurities are inseparably combined with the coal. The removable impurities are segregated and can be eliminated, by available cleaning methods, to... [Pg.906]

Very finely divided minerals may be difficult to purify by flotation since the particles may a ere to larger, undesired minerals—or vice versa, the fines may be an impurity to be removed. The latter is the case with Ii02 (anatase) impurity in kaolin clay [87]. In carrier flotation, a coarser, separable mineral is added that will selectively pick up the fines [88,89]. The added mineral may be in the form of a floe (ferric hydroxide), and the process is called adsorbing colloid flotation [90]. The fines may be aggregated to reduce their loss, as in the addition of oil to agglomerate coal fines [91]. [Pg.477]

Acetamide [60-35-5] C2H NO, mol wt 59.07, is a white, odorless, hygroscopic soHd derived from acetic acid and ammonia. The stable crystalline habit is trigonal the metastable is orthorhombic. The melt is a solvent for organic substances it is used ia electrochemistry and organic synthesis. Pure acetamide has a bitter taste. Unknown impurities, possibly derived from acetonitrile, cause its mousy odor (1). It is found ia coal mine waste dumps (2). [Pg.73]

Hot Corrosion. Hot corrosion is an accelerated form of oxidation that arises from the presence not only of an oxidizing gas, but also of a molten salt on the component surface. The molten salt interacts with the protective oxide so as to render the oxide nonprotective. Most commonly, hot corrosion is associated with the condensation of a thin molten film of sodium sulfate [7757-82-6], Na2S04, on superaHoys commonly used in components for gas turbines, particularly first-stage turbine blades and vanes. Other examples of hot corrosion have been identified in energy conversion systems, particularly coal gasifiers and direct coal combustors. In these cases the salt originates from alkali impurities in the coal which condense on the internal... [Pg.115]

The quahty of naphthalene required for phthaUc anhydride manufacture is generally 95% minimum purity. The fixed plants do not require the high (>98%) purity naphthalene product and low (<50 ppm) sulfur. The typical commercial coal-tar naphthalene having a purity ca 95% (freezing point, 77.5°C), a sulfur content of ca 0.5%, and other miscellaneous impurities, is acceptable feedstock for the fixed-bed catalyst process based on naphthalene. [Pg.484]

The main impurity in cmde 78°C coal-tar naphthalene is sulfur which is present in the form of thionaphthene (1—3%). Methyl- and dimethylnaphthalenes also are present (1—2%) with lesser amounts of indene, methylindenes, tar acids, and tar bases. [Pg.485]

Piebaked anodes aie produced by molding petroleum coke and coal tar pitch binder into blocks typically 70 cm x 125 cm x 50 cm, and baking to 1000—1200°C. Petroleum coke is used because of its low impurity (ash) content. The more noble impurities, such as iron and siUcon, deposit in the aluminum whereas less noble ones such as calcium and magnesium, accumulate as fluorides in the bath. Coal-based coke could be used, but extensive and expensive prepurification would be required. Steel stubs seated in the anode using cast iron support the anodes (via anode rods) in the electrolyte and conduct electric current into the anodes (Fig. 3). Electrical resistivity of prebaked anodes ranges from 5-6 Hm anode current density ranges from 0.65 to 1.3 A/crn. ... [Pg.98]

The zinc is normally melted in a gas, oU, or coal-fired reverberatory furnace with a capacity up to 100 tons or in a low frequency induction furnace with a capacity of a few tons. The more highly aUoyed compositions are more effectively melted and mixed in low frequency induction furnaces. The furnace must be refractory-lined to eliminate iron pickup by the molten metal. The metal temperature is maintained below 500°C to minimize loss by oxidation. A ladle is used to transfer the metal for casting into molds the pouring temperature is usuaUy ca 440°C. Zinc scrap is not generaUy suitable for remelting because it may contain undesirable impurities. [Pg.414]

Reactions of Goal Ash. Mineral matter impurities have an important effect on the utili2ation of a coal. One of the constituents of greatest concern is pyrite because of the potential for sulfur oxide generation on combustion. The highest concentrations of pyrite are associated with coal deposition under marine environments, as typified by the Illinois Basin, including parts of Illinois, Indiana, and Kentucky. Additionally, the mineral matter... [Pg.224]

Impurities. The three categories of potential pollutants in coal are sulfur, nitrogen, and ash. Sulfur and ash are associated with both the mineral and organic portions of coal, whereas nitrogen is mainly associated with the organic matter (4). [Pg.252]

The KEN-FLOTE column (11) is one of several column flotation processes based on a countercurrent principle. The feed slurry containing reagents is iatroduced iato the column just below the froth zone. Air is iujected at the bottom of the column via an air sparger. Wash water is sprayed within the froth zone to reject the entrained impurities from the froth. Test results on this column iadicate that a 6% ash product coal having a combustible-recovery of 75—80% can be obtained. A 70—80% pyrite reduction is also claimed. Figure 2 shows the operation of such a column. [Pg.254]

The use of a water-immiscible Hquid to separate coal from impurities is based on the principle that the coal surface is hydrophobic and preferentially wetted by the nonaqueous medium whereas the minerals, being hydrophilic, remain suspended in water. Hence, separation of two phases produces a clean coal containing a small amount of a nonaqueous Hquid, eg, oil, and an aqueous suspension of the refuse. This process is generally referred to as selective agglomeration. [Pg.255]


See other pages where Coal impurities is mentioned: [Pg.202]    [Pg.204]    [Pg.395]    [Pg.353]    [Pg.202]    [Pg.204]    [Pg.395]    [Pg.353]    [Pg.166]    [Pg.129]    [Pg.767]    [Pg.318]    [Pg.391]    [Pg.80]    [Pg.81]    [Pg.410]    [Pg.313]    [Pg.535]    [Pg.109]    [Pg.109]    [Pg.121]    [Pg.121]    [Pg.122]    [Pg.422]    [Pg.416]    [Pg.419]    [Pg.466]    [Pg.539]    [Pg.212]    [Pg.249]    [Pg.252]    [Pg.252]    [Pg.253]    [Pg.254]    [Pg.255]   
See also in sourсe #XX -- [ Pg.23 ]




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Impurities in coal

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