Alkali Elution Behavior of Steelmaking Slag Packed in an Open Channel Vessel in Seawater

Abstract

The alkali elution behavior of steelmaking slag in seawater was kinetically investigated and simulated under continuous flow in an open channel vessel with packed bed of steelmaking slag. Two types of steelmaking slags, viz. decarburization slag and dephosphorization slag, were used in this study. The alkali elution rate of decarburization slag was larger than that of dephosphorization slag due to larger free CaO content. The pH value for dephosphorization slag was almost the same as the seawater pH value in 3–4 days, whereas that for decarburization slag was stabilized in 3 days although the pH value was slightly larger than that of seawater. The capacity coefficients of alkali elution for dephosphorization and decarburization slags decreased together in an exponential manner with time. Based on a regression equation on the mass transfer capacity coefficient change with time, the alkali elution behavior was simulated and the calculated results agreed well with the experimental ones. The temporal pH change was predicted by changing slag surface area and seawater flow rate as a parameter. According to the simulation results for dephosphorization slag, the seawater pH value did not reach a high level in the ocean area.