الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Optimizing EAF slag chemistry to obtain suitable foaming characteristics is mandatory for steelmakers to keep running with a lowest operational cost. However, the control and optimization of the foam generation on the slag surface are still limited to some factors such as viscosity, surface tension, basicity, FeO concentration and how the suspended second phase particles in the liquid act directly in the slag; foaming behavior need some further understanding. Therefore, this work addresses the effect of slag magnesia content on foaming, experimental tests used for its evaluation and the use of thermodynamic data in order to control the slag composition. Considering the data presented in the scientific literature, there are various conditions and situations to be explored and thermodynamic calculations seem to be the most suitable tool for these investigations. Based on a technical study on long products steelmaking plant at Al Ezz Dekheila Steel Company (EZDK) shows II that the higher MgO content in feed charge (DRI), the lower refractory material consumption and vice versa. This work aims to improve refractory consumptions in EZDK-EAFs using a high MgO content material. Two trials were executed; the first trial depends on reusing of crushed waste Magnesia-Carbon bricks (2 ~ 8 mm size). 120 tons of waste bricks were enough to cover 173 heats. The material was charged into EAF by dose feeding during flat bath operation stage. Meanwhile, the other trial depends on using of 200 tons burnt dolomite (10 ~ 50 mm size) that charged and fed continuously with DRI. This trial lasts for 97 heats. Using published Isothermal Stability Diagrams (ISD), An empirical equation for MgO saturation point was introduced as a function of slag basicity (B2 and B3) depending on available data by “MAGNESITA REFRACTORIES” using statistical formulization tool (EUREQA 1.24®). Then, a material balance was executed to define the required MgO quantity in the slag. The effect of magnesia saturated slag and therefore enhanced foaming characteristics on refractory consumptions and operation parameters were monitored. Practically, the refractory lining life was enhanced by 30% and 21% while coating mix (refractory lining repair material) consumption was reduced by 39% and 28% in addition the bricks consumption was decreased by 9% in both crushed magnesia bricks and burnt dolomite trials respectively. In burnt dolomite trial, reducing slag basicity allows 0.6% increase of metallic yield, an average energy saving of 8 Kwh/TMS and 1.4 min/heat power-on time saving (≈ additional 0.4 heat/EAF/day), even with higher DRI ratio (+ 0.7%) and lower average total Fe in DRI (lower by 0.64%) for the same trial period.