A Simulation Study of Blast Furnace Hearth Drainage Using a Two-phase Flow Model of the Taphole

Abstract

The drainage of the hearth plays an important role for the operation of the ironmaking blast furnace. An undisturbed extraction of the produced molten materials from the hearth is a prerequisite of a smooth operation of the high-temperature region, and a good mixing of liquid iron and slag in the taphole and runner helps desulfurize the iron. The flows of molten iron and slag in the blast furnace taphole have not received much attention, even though several investigators have studied the hearth drainage phenomena. In the present paper a two-fluid model of the taphole flow, based on an assumption of full stratification of the two liquids, is developed, and coupled with a simple material balance for the furnace hearth. Furthermore, the pressure loss of the liquids in the dead-man in front of the taphole inlet is considered. Simulations with the model are applied to illustrate how different factors affect the drainage, liquid levels and taphole flow. It is demonstrated that the in-furnace conditions play an important role for the flows and the flow distribution between iron and slag. The effects of key variables, such as coke-bed voidage and coke size, are illustrated and conclusions concerning their impact on the drainage are drawn.