Crystallization characteristics, microstructural evolution, and Cr migration mechanism of glass-ceramics synthesized entirely from low-carbon ferrochromium slag and waste glass.

The disposal and large-scale reutilization of industrial solid waste in construction materials have been gaining considerable interest. Herein, the synthesis of glass-ceramics from low-carbon ferrochromium slag (FCS) and waste glass is reported. The crystallization characteristics, microstructural evolution, and Cr migration mechanisms of the glass-ceramics were investigated through offline quenching experiments. The physical properties and Cr ion leaching performance were tested and evaluated. As the low-carbon FCS content was increased, glass network depolymerization was promoted and the crystallization ability was effectively improved. When 50 wt% low-carbon FCS was added, the compressive strength and Vickers hardness of the glass-ceramics reached maximum values of 160.26 MPa and 736 Hv, respectively. Simultaneously, the dominant crystalline phase in glass-ceramics was transformed from diopside and wollastonite into gehlenite when the low-carbon FCS content was further increased to 60 wt%, thereby reducing the mechanical properties. CrO primarily existed as a [CrO] octahedron and Cr-containing spinel in the parent glass, resulting in composition segregation. On combining the growth orientation of diopside and spinel, the resulting specific crystal coating structure improved the Cr ion leaching performance. Considering the physical properties and risk of Cr leaching, the optimal FCS content in glass-ceramics is 40-50 wt%. These findings indicate that the production of glass-ceramics from low-carbon FCS and waste glass is an effective and environment-friendly method for co-utilizing these two solid wastes.