Kinetic Reduction of Pellets of Mill Scale Waste and El Dekheila Pellets Fine Waste using Coke Breeze

Abstract

Mill scale is a valuable waste material that contains high amount of iron, little impurities and also is chemically stable composition. It is produced from the hot rolling processing in steel industry. The second waste is El-Dekheila pellets fine waste that produced as the results of handling in the El-Dekheila plant, West of Alexandria on the Northern coast of Egypt. This paper studies the recycling of mill scale and El-Dekheila pellets fine waste in iron and steel industries by reduction using coke breeze in the form of pellets. Characterization of raw materials were performed which are XRF, XRD and screen analysis. Reduction of pellets consisting of El-Dekheila pellets fine waste and different percentage of mill scale was investigated with 4 stoichiometric coke breezes using thermo-balance. The reduction increases with increasing coke breeze. The kinetics of reduction of these pellets were studied using different percentage of mill scale (20,60 and 80%) and at different temperatures ranging from 900 to 1050oC. The results displayed that the reduction process was controlled by Avrami and Erofeev involving nucleation of reduced phases followed by grain growth. Also, that the maximum reduction 80% can be reached after 125 minutes using 20% mill scale. The activation energies of reduced 20, 60 and 80% mill scale were found to be 112 kJ.mol-1 , 81 kJ.mol-1 and 107.8 kJ.mol-1 respectively.