AbstractChromium, iron, and nickel are present in many waste-streams from DOE sites. This study considers a simplified lime-aluminosilicate glass system, similar to one proposed for high temperature (1250–1450°C) vitrification of soil and wastes from DOE sites, in which concentrations of Cr, Fe. and Ni are being varied and different redox states induced for selected melting conditions. The solubilities of Cr 2O3 and NiO in the simplified system are determined at 1350°C, 1400°C, and 1450°C. The enthalpies of solution calculated from the solubility data for Cr2O3 and NiO are 12.2 and 15.2 kcal/mol, respectively. The iron redox ratio, Fe2+/Fetotal in selected glasses is determined by Mössbauer Spectroscopy and related to changes in microstructure. The crystallization of eskolaite (Cr2O3) seems to be favored at intermediate states of reduction (Fe2+/Fetotal ≈0.8) in Cr-containing glass at near the solubility limit. Pseudoternary diagrams are plotted for melts in air at 1450°C in which Fe2O3 + SiO2 + X (X = NiO or Cr2O33) is held constant. Time-Temperature-Transformation (TTT) curves are plotted using data from heat treatment studies. Liquidus temperatures of base, 1.5 wt% Cr2O3 glass and 8 wt% NiO, 7 wt% Fe2O3 glass are found to be 1150°C, 1175°C, and 1175°C, respectively.
A Comparative Spectrophotometric Study Using Ferrozine and 1,10-Ortho-phenanthroline to Evaluate the Iron Redox Ratio (Fe2+/ΣFe) in Glass Prepared by Microwave Heating
