Bituminous carbon

Type 1240, from Bituminous Carbon Properties BET specific surface area 818 in-/g (original) [2615],... 

The chemical characteristics of biomass vary over a broad range because of the many different types of species. Table 8 compares the typical analyses and energy contents of land- and water-based biomass, ie, wood, grass, kelp, and water hyacinth, and waste biomass, ie, manure, urban refuse, and primary sewage sludge, with those of cellulose, peat, and bituminous coal. Pure cellulose, a representative primary photosynthetic product, has a carbon content of... 

Typically, 40—50% of the carbon atoms ia lignite are ia aromatic stmctures while 60—70% of the carbon atoms ia Illinois bituminous coal are ia aromatic stmctures (7,8). By all of these measures, waste fuels are significantly more reactive than coal, peat, and other combustible soHds. 

Tar sand has been defined as sand saturated with a highly viscous cmde hydrocarbon material not recoverable in its natural state through a well by ordinary production methods (2—8). Technically the material should perhaps be called bituminous sand rather than tar sand because the hydrocarbon is bitumen, ie, a carbon disulfide-soluble oil. 

In carbon adsorption, contaminants are physically attracted or adsorbed on the surface of the carbon. Adsorption capacities are high for carbon because its porous nature provides a large surface area relative to its volume. Activated carbon is prepared from lignite, bituminous coal, coke, wood, or other organic materials such as coconut shells. 

The principal binder material, coal-tar pitch, is produced by the distillation of coal tar. Coal tar is obtained primarily as a by-product of the destmctive distillation of bituminous coal in coke ovens during the production of metallurgical coke. Petroleum pitch is used to a much lesser extent as a binder in carbon and graphite manufacture. Because of its low sohds content, petroleum pitch is used as an impregnant to strengthen carbon artifacts prior to graphitization. 

Aromaticity of coal molecules increases with coal rank. Calculations based on several models indicate that the number of aromatic carbons per cluster varies from nine for lignite to 20 for low volatile bituminous coal, and the number of attachments per cluster varies from three for lignite to five for subbituminous through medium bituminous coal. The value is four for low volatile bituminous (21). 

Other Uses. The quantity of coal used for purposes other than combustion or processing is quite small (2,6). Coal, especially anthracite, has estabHshed markets for use as purifying and filtering agents in either the natural form or converted to activated carbon (see Carbon). The latter can be prepared from bituminous coal or coke, and is used in sewage treatment, water purification, respirator absorbers, solvent recovery, and in the food industry. Some of these markets are quite profitable and new uses are continually being sought for this material. 

Coal Hquefaction iavolves raising the atomic hydrogen-to-carbon ratio from approximately 0.8/1.0 for a typical bituminous coal, to 2/1 for Hquid transportation fuels or 4/1 for methane (4). In this process, molecular weight reduction and removal of mineral matter and heteroatoms such as sulfur, oxygen, and nitrogen may need to be effected. 

Adsorption. Adsorption (qv) is an effective means of lowering the concentration of dissolved organics in effluent. Activated carbon is the most widely used and effective adsorbent for dyes (4) and, it has been extensively studied in the waste treatment of the different classes of dyes, ie, acid, direct, basic, reactive, disperse, etc (5—22). Commercial activated carbon can be prepared from lignite and bituminous coal, wood, pulp mill residue, coconut shell, and blood and have a surface area ranging from 500—1400 m /g (23). The feasibiUty of adsorption on carbon for the removal of dissolved organic pollutants has been demonstrated by adsorption isotherms (24) (see Carbon, activated carbon). Several pilot-plant and commercial-scale systems using activated carbon adsorption columns have been developed (25—27). 

Essentially, carbonization entails the heating of organic precursors in the absence of air. In so doing, a solid carbon residue along with gaseous and volatile hydrocarbons is created. Bituminous coals are used to make metallurgical-grade coke while wood and other similar substances make charcoal. The condensed volatile material can be further refined to yield chermcals, pitches, or other useful commodities. 

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