Vitrification of a sodium chromate waste and mechanical properties of a final glass-ceramic

Abstract

The mechanical properties of a new glass-ceramic similar to basalt glass-ceramics have been determined. This new glass-ceramic is similar to those obtained from basalts and it is a resulting material from the vitrification of a highly contaminated sludge rich in hexavalent chromium (Cr6+). A formulated mixture between this industrial waste and silica-based additives was achieved within the CaO-MgO-Al2O3-SiO2 system. The Cr6+ can be fully reduced to Cr3+ with high chemical and mechanical stability, and the resulting material is stable for the environment. The Weibull modulus of flexural strength was m = 5.7, corresponding to a relatively low value, indicating that the breakage is due to a variable number of types of cracks. In any case, the average flexural strength of this material (258 MPa) can be considered as a relative high value when compared with the values of more traditional glass-ceramics. Keywords: Vitrification, Glass-ceramics, Mechanical properties, Weibull analysis, Chromate wastes