Influence of Fe3+/Fe2+ ratio on the crystallization of iron-rich glasses made with industrial wastes

The influence of the Fe3+/Fe2+ ratio on the crystallization of iron-rich gl asses was investigated in this study. The glass batches mere made from two hazardous industrial wastes: mud (goethite and jarosite) originating from t he zinc hydrometallurgical process and electric are furnace dust (EAFD), Gl ass compositions were prepared by adding different percentages of carbon po wder. The crystallization process was investigated by a combined thermograv imetry/differential thermal analysis technique, in air or nitrogen atmosphe res, using powder and bulk glass samples. The crystalline phases formed, i. e,, pyroxene and spinels, and their relative ratio were determined by X-ray diffractometry. The experimental results indicated that melting temperatur e and crystallization behavior mere influenced by the initial Fe3+/Fe2+ rat io and by the amount of carbon added to the glass batch. For goethite and j arosite glass compositions, decreasing the Fe3+/Fe2+ ratio increased the cr ystallization rate by favoring magnetite formation. For EAFD glass composit ions, the addition of carbon to the batch inhibited chromite-magnetite spin el formation and favored the attainment of an amorphous glassy phase.