8th International Congress on Science and Technology of Ironmaking - ICSTI 2018

Changes in heat transfer regularities of blast furnace process in course of this process refinement are considered and evaluated. It is shown that stable and profitable operation of modern intensive blast furnace process with variety of raw materials, combined blast etc. could be achieved only preserving two distinct zones of high intensive heat transfer. Any changes in melting process do not change this fundamental characteristic of blast furnace process. Heat exchange processes in the upper and bottom stages of blast furnace are not completely autonomous since both depends on extend of direct reduction process. Experimental and theoretical investigation of blast furnace process in modern conditions showed the existence of two zones of delayed heat exchange. The upper delayed heat exchange zone is characterized also as delayed mass exchange zone. Therefore, this volume of blast furnace from the heat transfer point of view could be considered as a reserve zone of blast furnace. In the lower zone of delayed heat exchange processes the speed of chemical reactions is comparatively high. Therefore, this zone cannot be considered as a part of reserve zone. From the point of view of heat exchange processes assessment and blast furnace control in modern conditions the furnace still has to be divided by two heat exchange zones – upper and bottom. The boundary between these zones is located at the upper levels of mixed reduction of iron oxide, between elevation of the beginning of carbon gasification reaction and the level, below which reduction of iron oxides characterized only by direct reduction.