EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

**Abstract** Proper understanding and control of accumulation, drainage and heat transfer of hot metal and slag in BF hearth is essential for a stable and efficient blast furnace operation. Abnormal drainage behavior may lead to high liquid build up in the hearth. Operation problems normally be encountered if the liquid levels in the hearth exceed a critical limit when hearth coke and deadman start to float. This not only cause sluggish or irregular descent of burden material but also result in irregular casting intervals, damage to lining, low blast intake and furnace pressurization. Similarly hot metal temperature is an important parameter to be controlled in the BF operation; it should be kept at an optimal level to obtain desired product quality and a stable BF performance. To predict the hot metal temperature variation during tapping process is extremely useful since it gives a clear picture to operator about the tapping operation and prevents any panic. At the same time it allows the correction of process parameters in case of any major deviation. The hot metal composition and quality depend on the casting temperature of the hot metal. If it is too high or too low it may directly affect the process and cost efficiency of BF as well as BOF plants. The level & temperature of the liquids in the hearth varies with time and is not fixed, it greatly changes with the tapping durations and production / drain rates along with changes in blowing parameters and fuel supply. Efforts have continu¬ously been made for BF process optimization to improve its pro¬ductivity, energy efficiency, environment and product quality. The control of the hot metal / slag accumulation, drainage pattern & tapping temperature is of great importance in order to optimize the BF process and make it productive, energy efficient and cost competent. Therefore it is utmost important for a furnace operators to understand the mechanisms governing the liquid flow, accumulation, drainage and heat transfer between various phases in blast furnace hearth. It is very difficult to carry out any direct measurement due to the hostile conditions in the hearth with chemically aggressive hot liquids. Hence estimation and simulation based on rules of physics and mathematical calculations, taking in account available operating parameters, is only viable solution. The objective here is to develop a mathematical model to simulate the variation in hot metal / slag accumulation and temperature during the tapping of the furnace based on the computed drainage rate, production rate, mass balance, heat transfer between metal and slag, metal and solids, slag and solids as well as among the various zones of metal and slag itself. The developed model is able to predict & give real time picture of state of liquids in the hearth, which is in good agreement with the actual plant data.