Influence of coal tar-water emulsion on carbonisation of caking coals

The influence of coal tar-water emulsion (CTWE) on the dynamics of carbonisation and characteristics of cokes obtained from single coals and their blends was studied. Carbonisation tests were carried out in a Karbotest unit and a laboratory coke oven using X-raying. The qualitative parameters of cokes CRI and CSR, the structure of the coal plastic layer, the thickness of its zones, and the intralayer pressure were determined. The coals and cokes carbonised were investigated using scanning electronic microscopy (SEM). It was found out that the addition of CTWE to coal during pyrolysis affects the structure of the plastic layer, changes the thickness of its zones as well as the parameters characterising the dynamics of the plastic mass movement during carbonisation. CTWE introduced to coal facilitates or hinders the release of decomposition products of the organic matter that is evidenced by SEM micrographs of swollen coal grains. Under the influence of the emulsion the surface of coal grains may become clogged. On examination it was found out that by changing the parameters of the plastic state and phenomena occurring during pyrolysis CTWE plays the role of an external plasticiser of the organic matter and a modifier of the surface of swollen grains. (C) 2007 Elsevier B.V. All rights reserved.