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

• Published in: Materials letters. X Vol. 4; p. 100025
• Main Authors: Ballesteros, S., Rincón-Mora, B., Jordán, M.M., Rincón, J.Ma
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-12-2019; Elsevier
• Subjects: Chromate wastes; Glass-ceramics; Mechanical properties; Vitrification; Weibull analysis; Mechanical properties; Glass-ceramics; Chromate wastes; Vitrification; Weibull analysis
• ISSN: 2590-1508; 2590-1508
• DOI: 10.1016/j.mlblux.2019.100025

•An industrial waste of sodium chromate sludge was vitrified into a like basalt glass.•This basalt glass, including toxic Cr6+, can be transformed into a glass-ceramic.•This new vitreous material, including toxic Cr6+, shows high mechanical properties.
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.