Transformation of unstable heavy metals in solid waste into stable state by the preparation of glass-ceramics

In this study, glass-ceramics were prepared from stainless steel slag and iron tailing. Consequently, unstable heavy metals were converted to stable. With the adding of stainless steel slag, crystallization temperature and the mechanical properties of the resultant glass-ceramics increased first and then decreased, and it was found that secondary phase (Spinel) differed from major phase (Augite). The results of toxicities leaching test and Tessier five step sequential extraction showed that Cr content in the exchangeable state, carbonate bind state, ferromanganese oxide state and organically bind state of the basic glass were 0.04%, 0.08%, 7.82% and 1.13%, respectively. However, in the glass-ceramics, they exhibited the low content of 0, 0.04%, 2.02% and 0.40%. The residual content of Cr reached to 90.93% in the glass, whereas 97.55% in the glass-ceramics, being higher than that in the glass. The results indicated that Cr enters the silicate lattice, so as to realize the curing of chromium.