Experimental Study on Calcination of Portland Cement Clinker Using Different Contents of Stainless Steel Slag

In order to increase the utilization rate of stainless steel slag, reduce storage needs, and mitigate environmental impacts, this study replaces a portion of limestone with varying amounts of stainless steel slag in the calcination of Portland cement clinker. The study primarily examines the influence of stainless steel slag on the phase composition, microstructure, compressive strength, and free calcium oxide (ƒ-CaO) content of Portland cement clinker. The results show the following: (1) Using stainless steel slag to calcine Portland cement clinker can lower the calcination temperature, reducing industrial production costs and energy consumption. (2) With an increase in the amount of stainless steel slag, the dicalcium silicate (C₂S) and tricalcium silicate (C₃S) phases in Portland cement clinker initially increase and then decrease; the C₃S crystals gradually transform into continuous hexagonal plate-shaped distributions, while the tricalcium aluminate (C₃A) and tetracalcium aluminoferrite (C₄AF) crystal structures become denser. When the stainless steel slag content is 15%, the dicalcium silicate and tricalcium silicate phases are at their peak; the C₃S crystals are continuously distributed with a relatively dense structure, and C₃A and C₄AF crystals melt and sinter together, becoming distributed around C₃S. (3) As stainless steel slag content increases, the compressive strength of Portland cement clinker at 3 days, 7 days, and 28 days increases and then decreases, while ƒ-CaO content decreases and then increases. When the stainless steel slag content is 15%, the compressive strength at 28 days is at its highest, 64.4 MPa, with the lowest ƒ-CaO content, 0.78%. The test results provide a basis for the utilization of stainless steel slag in the calcination of Portland cement clinker.