Use of asphalts for formcoke briquettes

Increasing demand for coke is coupled with diminishing supplies of cokeable coals. Formcoke technology, which involves briquetting of char, coke and/or raw coals with a binder material (usually coal tar), permits the use of a much wider range of coals as feedstock. The major objective of this study was to explore the use of petroleum residues as binders. The effects of properties of feedstock, char and binders, and operating conditions were investigated. The interaction of oxygen with the binder can be beneficial in increasing the mechanical strength of formcoke briquettes. The outcome depends on competing carboxyl-forming and depolymerization reactions. This interaction of oxygen with the binder can be effected through air-blowing and curing in air. The strength is also enhanced by the addition of asphaltenes and increased coking temperature. A new measure, the cokeable fraction of the binder, provided the best correlation with briquette strength. (C) 2002 Elsevier Science B.V. All rights reserved.