Test made by coal marketing companies and utilities on the Ash Fusion Temperature (AFT) of coals and coal blends provide a guide in assessing the coal quality. The test consists of a controlled heating of a prepared cone shape moulded ash sample in an oxidizing and a reducing atmosphere where temperature is recorded at which specimen shows an initial deformation, a spherical shape, a hemispherical shape and flow behaviour.
AFT prediction would assist in blending of coals and ensure that blends will have the required AFT. A model for AFT prediction based on thermodynamic computer package F*A*C*T is being developed in the Pyrometallurgy Research Centre, UQ. The degree of non-uniformity of temperature distribution in the AFT cone can greatly affect the accuracy of the AFT prediction. The significance of temperature distribution is evaluated in the present study by computer modelling of the thermal flow in the cone coupled with specially designed high temperature experimental measurements. Calculations are performed considering axis-symmetrical heat distribution of a cone. Heat profiles of the cone as a function of time are also investigated using one-dimensional solution.
Numerical results computed using MATLAB have been correlated with actual experimental data on thermal properties of mineral matter. The experiment results have been used to find the parameters of the model, which have then been use to predict the temperature gradient across the test cone. The reliable predictions of AFT are important for the systematic analysis and selection of coals, coal blends, coal mine planning, feasibility studies, coal marketing etc.