SOLIDIFICATION OF BOF SLAGS MODIFIED BY PYROMETALURGY AND SUBMITTED AT DIFFERENT COOLING RATES

In a scenario of blast furnace slag shortage, the use of BOF slag (Blast Oxygen Furnace) as a partial substitute in cement production is a low cost alternative. In this paper, BOF (Blast Oxygen Furnace) slag samples were melted in an experimental electric arc furnace (EAF), with different modifiers materials (Al top dross reject, slag from FeSi iron alloy production, et al.) with different rates of additions, subject to differentiated cooling in specifically designed experimental apparatus. The objective was to search the formation of different phases formed during a process of BOF slag modification, for different materials additions containing Al2O3 and SiO2 and subjected to different cooling conditions. Modified slags, with basicity (CaO/SiO2) below 1.1 and Al2O3 contents less than 5%, subjected to cooling rates up to 21°C/s, favor the formation of crystalline phases; no amorphous phases were detected in this trial. Modified slag tests with basicity below 1.2 and Al2O3 content between 10.0% and 12.5% favor both the formation of crystalline (majority) and amorphous phases (between 25% and 30%). The influence of the cooling rate up to 21°C/s on amorphous phase formation in this trial was not conclusive.