Physical and Chemical Characteristics of Coal-binder Interface and Carbon Microstructure near Interface

Abstract

In this study, investigations were made to understand the mechanism of increase in coke strength on binder addition by analyzing physical and chemical characteristics of coal-binder interface. Three binders, oil derived Asphalt pitch (ASP), coal derived HyperCoal (HPC) and Coal tar pitch (CTP) were used to understand the effect of binder. A new method to observe the coal-binder interface boundary at microscopic level by Scanning Electron Microscope (SEM) was developed. When base coal was a non-caking coal, coal-binder interface boundary was clearly observed by SEM for the first time. From observed images, it was found that ASP and HPC bound differently on the coal surface. When base coal is a caking coal, the interface could not be distinguished but sulfur mapping confirmed the presence of interface. Preliminary Laser Raman analysis suggests there may be some interactive effect of coal and binder on each other’s carbon structure development. Contribution of fraction of coal surface coated with binder towards coke strength is considered.