Glass-ceramics synthesis using the collaborative smelting slag of spent automotive catalyst and copper-bearing electroplating sludge

[Display omitted] •Glass-ceramics were prepared from SAC and CBES without additional nucleation agents.•Fe2O3 crystal acts as the crystal nuclei during the nucleation process.•The surface crystallization dominated the overall process of crystallization.•The sequence of crystal growth is augite, gehlenite and andradite.•The glass-ceramics exhibit good properties at sintering temperatures of 850 ℃–875 ℃. This paper studied the glass-ceramics preparation from the collaborative smelting slag of spent automotive catalyst (SAC) and copper-bearing electroplating sludge (CBES) by the one-step sintering method without additional nucleating agents. The crystallization mechanism, including nucleation and crystal growth steps, was investigated by DSC, XRD and FETEM-EDS. The crystallization process during heat treatment could be summarized as follows: Fe3+ ions will congregate firstly in a small range on the surface and inside of the originally homogeneous amorphous matrix, and then gradually crystallize and transform into stable hematite (Fe2O3) crystal nuclei. Augite and gehlenite as the main two crystalline phases grow around hematite (Fe2O3) epitaxially. Additionally, the surface crystallization dominates the overall process based on the crystallization kinetics calculation. The optimum sintering temperatures of glass-ceramics preparation were researched according to the physicochemical properties analysis. When the sintering temperatures are 850℃−875℃, the density, water absorption, Vickers hardness, flexible strength, acid and alkali resistance of glass-ceramics products are 2.8–2.9 g/cm3, 0.08%–0.09%, 6.5–6.7 GPa, 98–115 MPa, 96.6%–96.9% and 98.5%–99.6%, respectively. Toxicity characteristic leaching procedure (TCLP) test shows that the material can be taken as non-hazardous. This work realizes resource utilization and detoxification of the co-smelting slag of SAC and CBES.