Study of penetration and corrosion of olivine‐periclase and periclase based tundish DVMs by molten slag
Ironmaking & Steelmaking (Impact Factor: 0.71). 10/2011; 38(8):602-607. DOI: 10.1179/1743281211Y.0000000033
To enhance the billet caster tundish life, this study examines the relevance of the replacement of regularly used olivine?periclase based mixes by purer MgO containing dry vibe mass (DVM). After service, tundish working lining samples were studied by scanning electron microscopy energy dispersive spectroscopy to understand the influence of MgO saturation of the adhering slag and working lining interaction with the infiltrated slag. The result showed that the tundish working lining was penetrated and corroded by the molten slag for both DVM recipes. However, an increase in MgO content in the DVM exerted a chemical filtration to the molten slag, and the higher concentration of periclase dissolved into the slag, forming a saturated layer at the slag/refractory interface that resulted in the restriction of further slag penetration, probably due to an increase in the slag viscosity.
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ABSTRACT: The durability of insulating tundish linings depends on the sintering characteristics of the mix formulation and its ability to restrict corrosion. The present work studied the effect of mix variations on the performance of tundish working lining material. This was evaluated in terms of bond formation, strength and thermal conductivity of the lining material. In the present study, a siliceous olivine-periclase and a low silica magnesia based compositions were investigated. The samples evaluated were heat treated at 250–1450 °C for 2 h. Microstructure of the heat treated samples was analysed by QEM SCAN and SEM. A solid-state sintering by formation of high refractory phases like forsterite and magnesio-wustatite at the interface of the grains is believed to have enhanced the high temperature strength of olivine based recipe. In contrast, liquid phase sintering was predominant in periclase based formulation, imparting a lower strength at high temperature. The sintering behaviour of the mixes was also found to have a profound effect on thermal conductivity of the two materials.
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ABSTRACT: This study concerns the chemical reactions involved and the phases formed during penetration of slags of variable compositions into porous tundish disposable lining material. The liner is mainly composed of a mixture of MgO and olivine with an organic binder. Slags of different compositions were formulated and indicated a variable composition of CaO (12-20%), SiO2 (44-55%), Al2O3 (4-16%), MgO (10-20%), MnO (9-12%) and FeO (2-3%). Experimental work indicated that when slag penetrated into pores of the refractory, the porosity was reduced depending on the penetration depth. It was observed that the lower the melting point of the slag, the higher the depth of slag penetration by capillary action. The phases of forsterite (Mg2SiO4), magnesiowustite (MgO center dot FeO) and monticellite (CaO center dot MgO center dot SiO2) were formed in the bulk refractory by the slag, and the chief component of the refractory responsible for the formation of those phases is the periclase.
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