Increasing the Al2O3 content in the blast furnace slag, the blast furnace operations tend to make troubles such as excess accumulation of molten slag in the blast furnace hearth and increasing pressure drop at the lower part of the blast furnace. So, it will be important to keep good slag fluidity at the blast furnace operations such as, drainage of tapping and keeping good permeability.In order to clarify the effect of high Al2O3 slag fluidity on the blast furnace, high Al2O3 slag (20%) test operations of experimental blast furnace have been carried out. Investigation results of the test operation are as follows;1) Slag MgO improves the hearth drainage rate at high Al2O3 slag operation.2) Permeability of the dripping zone is improved by decreasing slag CaO/SiO2, at high Al2O3 slag operation of the blast furnace.3) It was verified that the slag drainage phenomena were able to described by the fluid model.4) The optimum composition of high Al2O3 slag of the blast furnace is high MgO and low CaO/SiO2.

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Effect of High Al2O3 Slag on the Blast Furnace Operations

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.

http://www.jstage.jst.go.jp/article/isijinternational/51/2/51_2_228/_pdf

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

Blast furnace hearth drainage: physical mechanisms

The blast furnace campaign length is today usually restricted by the hearth life, which is strongly related to the drainage and behavior of the coke bed in the hearth, usually referred to as the dead man. Because the hearth is inaccessible and the conditions are complex, knowledge and understanding of the state of the dead man are still limited compared to other parts of the blast furnace process. Since a number of publications have studied different aspects of the dead man in the literature, the purpose of the current review is to compile the findings and knowledge in a comprehensive document. We mainly focus on contributions with respect to the dead man state, and those assessing its influence on the hearth performance in terms of liquid flow patterns, lining wear and drainage behavior. A set of common modeling approaches in this specific furnace area is also briefly presented. The aim of the review is also to deepen the understanding and stimulate further research on open questions related to the dead man in the blast furnace hearth.

/pdf/dead-man-behavior-in-the-blast-furnace-hearth-a-brief-review-22ddk6dh7m.pdf

W.B.U. Tanzil

Papers

Blast furnace hearth drainage: physical mechanisms

A numerical solution for the drainage of two-dimensional packed beds