Assessment of the dissolution rate and behaviour of raw dolomite and limestone with different calcination degrees in primary steelmaking slags

Fluxes are added to steelmaking process to form basic slag and limit refractory lining consumption. Early formation of CaO- and MgO-saturated slag is critical for process productivity. To achieve this, flux must be dissolved in the melt in a limited process time, and the properties of a slag additive influence the fluxing efficiency. The dissolution behavior of samples with different qualities (i.e. raw dolomite, limestone, soft-burnt and hard-burnt quicklime and dolime) was investigated in the pre-melted model BOF and EAF slags at 1673 K and 1723 K. The disc-shaped sample was immersed into the melt and left there until slag solidification was reached. After a holding time between 5 and 20 minutes, the crucible with the sample were quenched with liquid nitrogen. The fused samples were analyzed by SEM method. Based on comparison of slag morphology and concentration changes in the slag, the dissolution behavior of the samples was examined.