Additions have extensively been used in the treatment of liquid iron and steel in pyrometallurgical processes. In these addition practices, the melting rates of the additions directly determine their recovery, which in turn affects the melt chemistry, the finished products and the production costs. The exothermicity of the additions plays an important role in enhancing the melting rates. A better understanding of the phenomena occurring during the melting is essential for promoting the use of exothermic additions in iron and steel making industry.

The objective of this study was to develop a mathematical model which simulates the coupled heat and mass transfer events occurring in melting processes associated with an exothermic htat of mixing. In this class of problems, the heat sink(i.e. latent heat of melting) and heat source (i.e. exothermic heat of mixing) co-exist in close proximity. The model wtis. based on the control-volume finite difference approach and on an enthalpy method. The predicted results were tested against experimental and numerical solutions of another investigator.

The computational results indicated that the exothermic heat of mixing leads to a rapid increase of temperature around the moving boundary, which produced an enhanced convective flow in the liquid phase. The intensification of fluid flow around the moving boundary resulted in an acceleration of the melting process.

In order to obtain an insight into the process of exothermic melting and to verify the mathematical model in detail, a low temperature physical model consisting of ice and sulfuric add solutions was established. In this physical modeL both temperature and velocity measurements were earned out The model results were compared with experimental measurements and they were found to be in good agreement.

The modd was also applied to predict fluid flow, heat and mass transfer during the melting of silicon in liquid high carbon iron. The predictions distinguished two periods present in the entire melting process. In the first period, the silicon was heated up. The second period, i.e. free melting period, occurred in company with the exothermic reaction, and consequently, the melting process was greatly accelerated. In comparison of the predicted results with the experimental results which include the force and velocity measurements, a reasonable agreement was obtained.