Steelmaking Slag Recycling as Raw Material and Its Effect on Burning Temperature of Portland Cement Clinker Production

Abstract

The valorization of industrial wastes plays a significant aspect in decreasing the environmental pollution. The discussed study concerns the recovery of steelmaking slag (SS), produced by a local steel plant, to make this by-product a raw material for portland cement clinker production. A lab study looks at this slag’s influence on the raw meal reaction capacity and technological parameters (temperature and burning time). Two clinkers were tested, the first is representative of portland cement clinker made in a cement plant, while the second is a clinker made in our laboratory in which SS replaces the pyrites residue used in the first. The raw meals were determined for the second clinker using different lime saturation factors from 0.89 to 0.95, while in the first clinker, lime saturation was 0.89. Chemical and mineralogical analysis and microscopic examination revealed that the usage of SS did not affect the resulting portland cement clinker. This slag enables a gain of 100°C on the clinkering temperature, usually 1,450°C, and shortens the burning time by 10 min. The main clinker phases (C3S, C2S, C3A, and C4AF) are present, with very few free-CaO, about 0.3%. The results of the physico-mechanical tests showed that adding SS had no impact on the cement’s quality. With a final compressive strength at 28-day of 43.5 MPa, the cement obtained satisfies the requirements for inclusion in Algeria’s CEM I 42.5 strength class.