Quinoline Insoluble Tutorial | Petrographic Atlas | SIU

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Crelling's Petrographic Atlas of Coals and Carbons

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Quinoline Insoluble Residues

Quinoline insoluble residues are solid carbon particles found in coal tars produced during the process of carbonization/coking. These residues are important because they strongly influence the behavior of pitches derived from the coal tar. These pitches are used as binders in the production of graphites as well as waterproof protective coatings, impregnants, and fuels. In a by-product coke oven battery the volatile components of the coal being coked are drawn off from the coking chamber and collected in a recovery system. These by-products consist of coal tar, light oil, ammonia, and gas.

To study the quinoline insolubles coal tar is solvent extracted with quinoline and the solid carbon particles remaining are term the quinoline insoluble residue. This residue is composed of materials derived from the by-products and coal related solids. The by-product carbons consist of normal or primary QI, pyrolytic carbon, pitch coke, and tar solids. The coal related solids consist of char cenospheres, coke fragments, coal particles, and mineral matter. Occasional carbon additives and miscellaneous carbons are also seen.

Description of Quinoline Insoluble Carbon Forms

By-product related Carbons
Normal or Primary QI Very small particles of the decomposition products of hydrocarbons particularly thermal black (products of thermal decomposition of hydrocarbons) and carbon black (products of incomplete combustion)
Pyrolytic Carbon Coatings of gaseous hydrocarbon decomposition that occur as spheres or bytroidal aggregates of spheres that show strong anisotropy
Pitch Coke Strongly anisotropic particles of coke derived from pitch
Tar solids Solid particles of isotropic tar

Coal-Related Solids
Char Cenospheres Isotropic and anisotropic carbon spheres and fragments derived from partial combustion of coal particles
Coke Isotropicand anisotropic fragments of coke from the coke oven chamber
Coal Fragments of coal carried over from the coke oven chamber
Mineral Matter Mineral particles derived from coal
Miscellaneous Carbons Carbon additives or contamination products


Gray, Ralph J. and Krupinski, Ken C., 1997, Pitch Production: Supply, coking, optical microscopy and applications: in Marsh, Harry, ed., Introduction to Carbon Technologies, Universidad de Alicante, p. 329-423.

Gray, R. J. and Rhoades, A. H., 1984, Microscopic analysis of quinoline insoluble residue from coal-tars and pitches: Proc. 43rd Ironmaking Conf. AIME, Chicago, v. 43, p. 319-325.