Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Physical Chemistry

Energy efficiency and air pollution nowadays is one of the biggest concerns worldwide. Increasing energy cost, electric as well as chemical energy, is forcing steel makers to reduce their manufacturing cost to gain competitive profits. Worldwide crude steel production in 2017 was around 1600 million tonnes. Around 25% of that quantity is melted by using electric arc furnace. In electric steelmaking, the second highest cost after raw material is the energy. The objective of this study is to find the optimum slag properties for lowest energy consumption and air pollutants in electric arc furnace and to investigate the main slag properties that affect its behavior in electric arc furnace. Slag electrical conductivity was studied experimentally. It was found that, electrical conductivity increases with increasing temperature, %FeO, %CaO and basicity B2. On the other hand, electrical conductivity was decreased with increasing SiO content. Specific conductance and 2 electric conductivity index for slag main constituents were also estimated. Relation between slag electrical and thermal conductivity was also studied and their inversely proportional was proved. Effect of slag temperature on its viscosity, thermal conductivity, electrical conductivity, density and surface tension was studied. Also effect of FeO content in slag on its thermal conductivity, electrical conductivity, density and surface tension was studied. Slag melting behavior was also studied experimentally. It was found that, initial deformation temperature found to be at the range 1400 - 1450 {u00B0}C. Softening temperature was at the range 1420 - 1485{u00B0}C while hemispherical temperature was at the range 1430 - 1490 {u00B0}C. Finally flow temperature was at the range 1460 - 1519 {u00B0}C depending on basicity ratio and FeO content. Also those values were decreased as the basicity and FeO increased. EAF chemical analysis and phase identification was carried out for slag of majority of Egyptian plants. MgO saturation level in EAF slag was determined experimentally and found 7.5%

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