Blackwell Publishing Journal Backfiles 1879-2005
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Chromium, an EPA listed toxic element concentrated in many industrial wastes, was stabilized using waste vitrification. Cr2O3 and CrO3 were loaded into a simulated basaltic base composition, vitrified, and cooled at various rates. Chromium incorporation mechanisms, vitrification processability, effect of initial Cr oxidation state, and product performance were investigated. At 1500°C, Cr2O3 has a low solubility limit (0.54 wt%) in the base composition, and crystallized as Cr-rich primary spinel (Mg,Fe)(Fe,Al,Cr)2O4. On cooling, Cr-depleted secondary spinel and augite (Na,Ca)(Mg,Fe2+,Al)(Si,Al)2O6 crystallized. Cr(VI) was converted into Cr(III) on vitrification. The apparent viscosity of the melts was estimated using the Bottinga–Weill model as corrected by Roscoe's equation. The end products showed Cr2O3 loading capacities as high as 16.7 wt% without exceeding the toxicity-leaching limit defined by EPA. The annealed products had Vickers's hardness of about 800 kg·F/mm2 and can be classified as medium-grade abrasives.
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