Quantitative evaluation of free CaO in electric furnace slag using the ethylene glycol method

Worldwide increase in the amount of slag production, a by-product of steel manufacturing, has led to efforts to recycle the slag into value-added products. However, the presence of unstable constituents like free CaO limits the applications of electric furnace slag, which is stabilized by the aging process. Herein, by measuring the free CaO content as a function of aging period, source region, company, and storage position, using the ethylene glycol method, the feasibility of using electric furnace slag as a construction material is confirmed. The free CaO contents of electric furnace oxidizing slag (EOS) samples were found to be below 0.5%. This satisfies the criteria specified in KS F 4571, which states that the CaO content should be below 40% and CaO/SiO2 ratio should be below 2.0. In addition, it was confirmed that free CaO content difference appears to be dependent on the aging period and storage position.