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

Abstract

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.