Thermal degradation of cold cured anthracite/coke breeze briquettes prepared from a coal tar acid resin

Abstract

Phenolic resoles were synthesised using a coal tar acid fraction of the oil fi om a low temperature carbonisation process. Anthracite/coke breeze briquettes with excellent physical properties have been prepared using the tar acid resoles, cured at ambient temperature. When the briquettes were combusted in an air oven, they retained their core shape up to 80% weight loss (d.a.f. basis). Thermogravimetric analysis-mass spectrometry (TGA-MS) was performed on a selection of acid cured resoles, as well as the cold cured briquettes bound with the resoles. The thermograms of the acid-cured resites showed significant volatile release at around 100 degrees C, corresponding to sulphuric acid breakdown and formaldehyde release. Further release of these volatiles occurs at 200 degrees C by when all the ether bridges in the cross-linked resin have been converted into methylene ones. Benzene, toluene, xylenes, phenol, cresols and xylenols were all released between 500 and 600 degrees C from the carbonisation of the resin. The thermograms of the briquettes bound with the coal tar acid resole solution displayed similar profiles, but further release of sulphur dioxide occurs at 500 degrees C, possibly due to the breakdown of acid entrapped within the briquette.