An Experimental and Computational Study on the Melting Behaviour of AOD and Chromium Converter Slags

Abstract

The campaigns of the AOD and chromium converters are often limited by the strong wear of the refractory materials in certain areas (usually tuyere zone). Slag protection (in which the slag is left to solidify at the converter walls after the tapping of the metal) has been considered to be an option in prolonging the campaigns of the converters. In order to study the possibilities of the slag protection, the purpose of this work was to determine the melting behaviour of the AOD and chromium converter slags; i. e. the solidus and liquidus temperatures and the composition of solid phases as a function of temperature in different slag compositions. Examination was executed using both computational (FactSage software) and experimental (optical diiatometerlSEM) methods. It was noticed that when burned dolomite was added into the slags, the increased MgO-contents had a strong influence on the melting behaviour. Even small changes (a few percent) in the MgO-content had a very strong influence (a few hundred degrees centigrade) on the solidus and liquidus temperatures. Solid phases that are formed during the solidification are also different in slags with and without burned dolomite addition.

Numerical Modeling of Argon‐Oxygen Decarburization Slag Cooling

“…[ 21 ] Furthermore, problematic phases, such as dicalcium silicate, may form during the slower cooling of AOD slags and cause disintegration of larger particles into dust due to volumetric changes related to mineralogical changes as temperature decreases. [ 34 ] If the crystallization during the cooling cannot be avoided, i.e., the cooling rate of the slag is not fast enough, the formation of the most harmful minerals, such as dicalcium silicate mentioned earlier, could be avoided by mixing different kinds of slags before the cooling and thus directing the slag composition into an area in which less harmful minerals are formed. [ 35 ] Generally speaking, the amorphous structure is more easily obtained for slags with higher SiO 2 contents because the required cooling rates for the basic slags are extremely high.…”

Modelling of the Refining Processes in the Production of Ferrochrome and Stainless Steel

“…Obviously the consideration of the oxidation reactions is not the only application for which thermodynamic modelling can be applied in the AOD, but other applications of less relevance such as solidification of the slag and its utilization to protect the refractory material (Heikkinen et al, 2004) are omitted here.…”

Holistic Analysis on the Concept of Process Metallurgy and Its Application on the Modeling of the AOD Process

“…Aim of the Modeling Physical as well as numerical modeling of the AOD and basic oxygen furnace (BOF) processes has been one of the main areas of metallurgical research at the University of Oulu (Oulu, Finland) for many years. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] During the last 5 years, the research has concentrated on the numeric modeling of the AOD process, specifically on the nitrogen content and fluid flows as a function of blowing time. The purpose of research has been the optimization of the AOD process by creating a simulation tool that makes it possible to study the effect of process alterations on the stainless steel production.…”