Existing state and solidification characteristics of heavy metals in glass‐ceramics from Mn‐bearing blast furnace slag

In this article, the high performance glass‐ceramics were prepared with Mn‐bearing blast furnace slag as the main raw material, Fe2O3 and Cr2O3 as composite nucleating agents. The existence state of Mn and Cr in glass‐ceramics and the mechanisms of solidification of heavy metals in glass‐ceramics were studied. The results showed that the high electric field characteristics of Cr ions contributed to the generation of spinel phase, while Mn ions can enter the spinel crystal by replacement method and exist stably in spinel crystal. The Mn ions were mainly distributed in the main crystalline phase of augite, the spinel phase and the glass phase. The depolymerization effect of the Mn ions in glass phase improved the crystallization characteristics of the glass‐ceramics, and promoted the transformation of the crystal morphology from dendrites to spherulites. Correspondingly, the density and Vickers hardness of glass‐ceramics showed an increasing trend with the increase of MnO2 additions, while the acid resistance and bending strength generally showed a decreasing trend. The result of leaching characteristics of heavy metals in glass‐ceramics suggested that the leaching concentration of heavy metals Cr and Mn were much lower than the standard value of leaching toxicity of hazardous waste, which indicated that the glass‐ceramics has a good stabilizing effect on heavy metals Cr and Mn. The results showed that the conversion of Mn‐bearing blast furnace slag into environmentally friendly glass‐ceramics can realize solid waste resource utilization.