Approach to the management of magnesium slag via the production of Portland cement clinker

Abstract

This work aims to develop another approach to the management of magnesium slag (MS) via the production of Portland cement clinker. Thus, 0, 10, 20, 30, 40 and 50% limestone was replaced by MS and the clinker was sintered. The burnability of the clinker, immobilization of heavy metals in the clinker, crystalline phases, micrograph of the clinker, the setting time of paste, compressive strength and leachability of heavy metals in the hardened paste were investigated to assess the feasibility of disposing the MS via production of Portland cement clinker. The results show that MS is favourable for improving the burnability of the clinker. The heavy metals from MS are stabilized/immobilized in clinker. MgO and CaF2 in MS increase the quantity of the liquid phase. All major phases of Portland cement appear in all clinkers with MS. However, the content of C3S in the clinker is related to the MS content. Less than 30% MS shortens the setting times of cement and increases the compressive strength for the increment of the C3S content in these clinkers. Excessive MgO and CaF2 lead to the decrease of C3S and appearance of unconventional cement phases of α-C2S and γ-C2S in MS4 and MS5. Thus, the setting times of MS4 and MS5 are prolonged, and their compressive strengths are also reduced. Heavy metals in clinkers are immobilized or stabilized in hydrated matrices. MS disposal via the production of Portland cement as a raw material alternative is also environmentally safe.