Influences of Slag Tapping Conditions on the Amount of Residual Slag in the Blast Furnace Hearth

Abstract

The resuUs of lhe model experiments about the slag flow in the blast furnace hearth') have been combined with the slag balance in lhe hearth to give an equal ion which relates the slag tapping conditions to each other. The following results were oblained by using lhe equal ion for the simulalion of the slag tapping operalion as well as for the analpes of operational dala: (1) The calculaled amount of slag lapped agreed well with lhat observed. (2) An increase in lhe calculated amount of residual slag caused the blaslfurnace hanging morefrequentLy. (3) The residual amounl of slag and the depth of slag layer at the beginning of ils flow-out increased wilh lhe increase in lhe rale of slag tapping and in lhe viscosity of slag. (4) The increase in the number of lapping operations was beneficial 10 reduce the de/Jtlt of slag layer.

Off-line Model of Blast Furnace Liquid Levels

“…5) The slag viscosity also gives rise to a downward bending of the slag-gas interface toward the taphole, which leaves considerable amounts of residual slag in the hearth as the tap ends when gas bursts out from the taphole. 6,7) These phenomena make the time evolution of the liquid levels during the tap cycle complex. Furthermore, in large furnaces the liquid levels may be fundamentally different in the region close to the draining taphole and on the opposite side, particularly if the deadman voidage is low, e.g., due to impermeable zones 8,9) caused by poor coke quality or by coke fines that accumulate in the bed because of improper combustion of excessive injection rates of pulverized coal.…”

“…They applied a slot model with two immiscible liquids to demonstrate the theory and also discussed the bending of the slag surface at the end of the tapping, revising the original findings of Fukutake and Okabe. 6,7) Zulli 11) further refined the expression of the residual slag, considering the motion of the iron-slag and slag-gas interfaces. Later, Nouchi et al 12) experimentally studied the influence of different deadman voidages, including cases where the core of the deadman was clogged, on hearth drainage and the outflow rates of the two liquids.…”

“…To estimate when this happens, several investigators have studied the system in laboratory scale and proposed correlations, e.g., for the flow-out coefficient. [5][6][7]11) Factors affecting the amount of residual slag are the slag outflow rate, slag viscosity, deadman voidage and coke diameter. As most of these (local) properties are unknown in the practical operation of the blast furnace, a simplified tap-end condition was applied here where ω is a model parameter and subscript j* denotes the draining pool.…”

Experimental Model Study of Liquid–Liquid and Liquid–Gas Interfaces during Blast Furnace Hearth Drainage

“…Detailed investigations of the interface phenomena have been Due to the importance and complexity of the behavior of the interfaces, many studies of the interface phenomena in the hearth have been done in small-scale experimental models and using sophisticated numerical simulation models. Tanzil et al [3][4][5] were the first to shed light on the general motion and bending of the interfaces in the BF hearth during drainage, partly revising the findings of Fukutake and Okabe [13]. Detailed investigations of the interface phenomena have been conducted based on the general findings by Tanzil et al [3][4][5] and by Zulli [6].…”

Physical modelling of hot metal flow in a blast furnace hearth

“…Fukutake & Okabe [2,3] studied the effect of the rate of tapping, the viscosity of slag and the number of tapping operations on drainage of viscous liquids and developed an empirical relationship between the amount of residual slag and the above-mentioned parameters. Tanzil, Pinczewski and co-workers in Australia extended the modelling work, e.g.…”