Dissolution of slag modifiers and fluidizers during the hot stage BOF slag engineering process
In recent year many possibilities have been explored for the utilization of Basic Oxygen Furnace (BOF) slag. BOF slag amounts to nearly half of the substantial quantities of steel slag being produced in Europe. Thus, the demand of high value added utilization of BOF slag is substantial. It is very important to control the final composition and mineralogy of the solidified slag before it can be utilized as a construction material, for example, cement binder or inorganic polymers. Hot stage processing of BOF slag plays a big part in this, during which, slag modifiers such as alumina or silica can be added to slag so that the final slag mineralogy of the slag will be stable as well as effective for utilization in binders. Therefore, understanding of the dissolution behaviours of the modifiers (e.g. SiO2, Al2O3) into the slag is of significant importance for the process optimisation of the hot stage slag engineering. Fast dissolution is desired because the solid compositional modifiers (e.g. SiO2, Al2O3) need to be dissolved into the BOF slag for the slag engineering reactions, such as the stabilisation reaction with the free CaO and MgO. In this study, the dissolution behaviour of alumina particles in molten BOF slag has been studied at various temperatures. The dissolution profiles of the particles has also been investigated. The effect of particle size and density on the dissolution behaviour has been discussed. It has been found that alumina particles dissolve incongruently in the concerned slag system. The various phases formed during the dissolution process and their behaviour in the dissolution zone has been studied for a better understanding of the process.