ASH FUSION TEMPERATURES AND THE TRANSFORMATIONS OF COAL ASH PARTICLESTO SLAG

A mechanistic study is detailed in which coal ash is heated with its s hrinkage measured continuously up to a temperature of 1600 degrees C. The temperatures corresponding to the rapid rate of shrinkage correspo nd to the formation of eutectics identified on phase diagrams. Samples were therefore heated to these temperatures, cooled rapidly and exami ned using a scanning electron microscope (SEM) to identify the associa ted chemical and physical changes. The progressive changes in the rang e of chemical composition (from SEM), the extent of undissolved ash pa rticles and porosity were then quantified and related to homogenisatio n, viscosity and ash fusion mechanisms. Alternate ash fusion temperatu res based on different levels of shrinkage have also been suggested to characterise the ash deposition tendency of the coals. (C) 1998 Elsev ier Science B.V. All rights reserved.