https://doi.org/10.15255/KUI.2004.029
Published: Kem. Ind. 54 (10) (2005) 425–428
Paper reference number: KUI-29/2004
Paper type: Professional paper
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Influence of Composition and Structure on Coal tar Pitch Quality

A. Rađenović and M. Legin-Kolar

Abstract

Besides physical – chemical characteristics of pitches (softening point, viscosity, density, volatile matter, carbon content, ash content) their group composition determined by organic solvents (quinoline, benzene, toluene, acetone) is important, too. The presence of insoluble substances in coal tar pitch, their properties and condition under which they form the mesophase during carbonization process, exert a strong influence upon the many characteristics of carbon material. Therefore, in this paper the group composition of two different coal tar pitch fractions soluble in organic substances (α and β fraction), are investigated. The results obtained showed that the pitch A, in relation to pitch B, contains more quinoline insoluble substance (α1 fraction – 7.1 %; α2 fraction – 30.1 %) and β fraction 30.3 %, but this is in the allowable limits. Coal tar pitches are employed as binders in carbon electrodes used in the production of steel and aluminum or carbon fibres and composites. Mass fractions of metals and nonmetals (especially sulphur) improve on the characteristic of carbon materials. Experimental results showed that the both of pitches have relatively low ash and investigated metal contents (Na, Ca, V). Sample B has high amount of sulphur (0.71 %) therefore its usage may be limitated. However, heat treatment of pitches during carbonization or production of carbon materials can decrease amount of present impurities and sulphur. The results obtained suggested that the both pitch samples (especially sample A) are suitable for use as component of feed for production the more valuable carbon materials.

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Keywords

coal tar pitch, primary carbonization, α and β fractions, metals, sulphur