Removal of Lead Ions by Various Types of Steel Slags

Steel slags are the by-products of steel industries, which are formed during reduction process of iron melting. The chemical composition of it changes depending to the melting procedure. Its mineralogical composition also varies based on the cooling procedure. Two different types of steel slag were used as absorbing bed for various concentrations of Pb $^{2+}$ ions in the form of lead chloride, and the concentrations of lead ions were measured in the effluent by atomic absorption spectroscopy. When Electric Arc Furnace Slag (EAFS) which is a basic crystalline slag was used in the presence of various concentrations of Pb $^{2+}$ , ranging from 2 mg/l up to 10 mg/l, the Pb $^{2+}$ ions were leached out into the solution and its concentration increased at the beginning of reaction but decreased dramatically up to 48 hours that the reaction was continuing but with slower rate. Almost the same thing happened when granulated blast furnace slag (GBFS), which is also a basic slag but in the amorphous mineralogical form, was used as the absorbing bed. The extent of ion release was much lower compared to EAFS but the absorption of lead ions took place with the higher rates. Based on this research, if EAF slag was used as absorbing bed for reduction of lead ions in the industrial waters, it takes 24 hours to absorb 10 mg/l of lead ions, while if blast furnace slag was used, maximum amounts of lead was absorbed in the first thirty minutes of reaction.