ПІДВИЩЕННЯ ЕНЕРГОЕФЕКТИВНОСТІ ДУГОВОЇ СТАЛЕПЛАВИЛЬНОЇ ПЕЧІ ШЛЯХОМ ВДОСКОНАЛЕННЯ СИСТЕМИ АСПІРАЦІЇ ТА РЕЦИКЛІНГУ ПЛАВИЛЬНОГО ПИЛУ

Abstract

Electric arc furnace (EAF) is considered as a basis of promising micrometallurgical complexes of Ukraine with a flexible production program. It is important to increase energy efficiency of the furnace, which depends crucially on heat loss (up to 12-20% of energy input) and iron loss (up to 20-22 kg/t of steel) with off-gas through disadvantages, inherent for EAF aspiration system, in comparison with BOF one. Purpose of the work is to reduce heat and iron loss with off-gas environment and recycling of melting dust. Research methodology consists in numerical modeling of new solutions for EAF aspiration and liquid-phase reduction of iron. The concept and basic solutions of dispersed aspiration system and liquid-phase process of carbon-thermal reduction of iron-containing wastes in heat- generating slag bath of electric resistance furnace with bottom electrodes are developed and substantiated. It has been experimentally established that increasing the aspiration surface, its distribution between the central and peripheral parts of the roof and approaching to area of electrode passage reduces unorganized emissions into electrode gaps by 40 % and air inflow into slag door by 10 %. Simulation of thermal state of a hearth with liquid cast iron under a layer of slag, which emits Joule heat, showed the need for forced mixing of the bath under conditions that multiplier, taking into account the effect of convection on coefficient of stationary thermal conductivity in the slag bath is at least 2.7. Experimentally determined power consumption is 2.12−2.29 kWh/kg of metallized product, which corresponds to the best foreign analogue "ITmk3". Estimation of expected economic effect of developments in the conditions of 120-t EAF only due to reduction of iron loss with melting dust by using of dispersed aspiration system is about 5 million UAH per year.