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High iron content glasses: an alternative in the use of electric arc furnace dust

University of British Columbia

Electric arc furnace baghouse dust (EAF) represents an environmental problem, both in terms of temporary storage and, ultimately, safe disposal. Vitrification of the dust so that hazardous components (such as zinc, lead, chromium, cobalt, barium, and arsenic) are incorporated into the glassy structure is one option for environmentally benign disposal which is currently being explored commercially in silica-based glasses with levels of iron up to 15 wt%. However, the ability of vitreous materials to resist leaching of hazardous components may be substantially reduced by components which promote crystallinity, in particular Fe, Zn, Cd, and other transition elements. In the present work, the impact of Fe₂O₃on the vitrification process has been explored experimentally, with the objective to generate glasses of high iron content. Several compositions were prepared in the system Fe₂O₃- ZnO - CaO - MgO - Na₂O at 50 wt% SiO₂and 1500 °C. Amorphous products were obtained with Fe₂O₃content varying from 15 to 35 wt%. The influence of Zn, Cd, and Pb in the silicate melt was also studied, with emphasis on the effect of these elements on high iron content glasses. The addition levels were within the range of variation of these elements in E A F dusts. The suitability of high iron vitreous products to retain hazardous metallics is normally tested under standard leaching tests designed by special wastes protocols. Silica glasses with zinc and glasses containing both iron and zinc, as well as their crystallized samples, were tested in order to determine both the leaching resistance and the influence of crystallinity on the leaching process. Satisfactory results in the leaching tests show the versatility of silica glass to incorporate hazardous elements such as zinc, render the products non-toxic and hence create an alternative to expensive disposal costs associated with EAF dust.

Thesis/Dissertation

application/pdf

2009-02-02

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http://hdl.handle.net/2429/4094

Mining Engineering

University of British Columbia

UBCV

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