Anthracitization

Coals (the plural is deliberately used because coal has no defined, uniform nature or structure) are fossil sources with low hydrogen content. The structure of coals means only the structural models depicting major bonding types and components relating changes with coal rank. Coal is classified, or ranked, as lignite, subbituminous, bituminous, and anthracite. This is also the order of increased aromaticity and decreased volatile matter. The H C ratio of bituminous coal is about 0.8, whereas anthracite has H C ratios as low as 0.2. 

Fig. 4.2 Adsorption isotherms of benzene at 25°C on (1) a charcoal from anthracite coal, activated to 56% yield (2) an activated coconut charcoal. (After Cadenhead and Everett.)...

Location Anthracite and bituminous coal Lignite Total... 

Deep Bed Filters. Deep bed filtration is fundamentally different from cake filtration both in principle and appHcation. The filter medium (Fig. 4) is a deep bed with pore size much greater than the particles it is meant to remove. No cake should form on the face of the medium. Particles penetrate into the medium where they separate due to gravity settling, diffusion, and inertial forces attachment to the medium is due to molecular and electrostatic forces. Sand is the most common medium and multimedia filters also use garnet and anthracite. The filtration process is cycHc, ie, when the bed is full of sohds and the pressure drop across the bed is excessive, the flow is intermpted and solids are backwashed from the bed, sometimes aided by air scouring or wash jets. 

E. J. Gottung and S. J. Sopko, "Design and Operation of a CEB Steam Generator Firing Anthracite Waste," presented at the 1988Joint AS ME/IEEE Power Generation Conference, Philadelphia, Sept. 25—28,1988. 

B. W. Wilhelm and co-workers, "100 MW Anthracite Culm CFB Small Power Producer," Proceedings of the American Power Conference, Vol. 50, Illinois Institute of Technology, Chicago, 1988. 

Fig. 3. Comparison of burning profiles for coals of different ranks where ( ) represents anthracite (-) semianthracite ( ) LV bituminous (° ) HV...

Includes coal, anthracite culm, and coal waste. 

Primary smelting can be carried out in a reverberatory, rotary, or electric furnace. The choice depends more on economic circumstances than on technical considerations (3). Thus, in the Far East, reverberatory furnaces fired with anthracite coal as the reductant were and still are widely used. 

Filtration does not remove dissolved soHds, but may be used together with a softening process, which does reduce the concentration of dissolved sohds. For example, anthracite filtration is used to remove residual precipitated hardness salts remaining after precipitation softening. 

The traveling-grate furnace requires less labor, increases the output per unit of grate area, and produces more uniform product than the WetheriU. furnaces. The traveling grate is an endless chain of cast-iron bars, driven by sprockets, which traverses a firebrick chamber. Anthracite briquettes are fed to a depth of ca 15 cm. After ignition by the previous charge, the coal briquettes are covered by 15—16.5 cm of ore/coal briquettes. The latter are dried with waste heat from the furnace. Zinc vapor evolves and bums in a combustion chamber and the spent clinker faUs into containers for removal (24,25). 

Ca.rhothermic Reduction. Sihcon carbide is commercially produced by the electrochemical reaction of high grade siUca sand (quartz) and carbon in an electric resistance furnace. The carbon is in the form of petroleum coke or anthracite coal. The overall reaction is... 

Anthracite. Anthracite is preferred to other forms of coal (qv) in the manufacture of carbon products because of its high carbon-to-hydrogen ratio, its low volatile content, and its more ordered stmcture. It is commonly added to carbon mixes used for fabricating metallurgical carbon products to improve specific properties and reduce cost. Anthracite is used in mix compositions for producing carbon electrodes, stmctural brick, blocks for cathodes in aluminum manufacture, and in carbon blocks and brick used for blast furnace linings. 

Anthracite is calcined at appreciably higher temperatures (1800—2000°C). The higher calcining temperatures for anthracite are necessary to complete most of the shrinkage and to increase the electrical conductivity of the product for use in either Soderberg or prebaked carbon electrodes for aluminum, siHcon, or phosphoms manufacture. 

Since anthracite must be calcined at higher temperatures than can be reasonably attained in conventional gas-fired kilns, an electrically heated shaft kiln is used to calcine coal at temperatures up to 2000°C (8). 

The primary constituent is calciaed anthracite coal particles. 

Sulfur dioxide [7446-09-5] and methane react to form carbon disulfide in a yield of 84% at 850°C in the presence of certain catalysts (107). Sulfur dioxide and anthracite at 900—1000°C produce very high yields (108). 

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