Abstract
Recycling of the metallurgical slag is critical for sustainable development of the industry. The primary concern in the geotechnical applications of the slags is the susceptibility to natural leaching. A systematic knowledge-based approach is essential to decrease the environmental impact of slag reuse and thus enhance the recycling of the industrial slags. The current study is focused on the fundamentals of the leaching behavior of synthetic amorphous slags in the “FeO” – SiO2 – MgO system with heavy elements Pb and Cu impurities. Compositions of synthetic slags are selected using the high-temperature equilibria studies and the predictions of internally developed thermodynamic models. The samples are prepared under laboratory controlled conditions and carefully characterized. Special technique for the bulk leachability experiments is developed to systematically investigate pH-dependent elusion of elements into the leaching medium. Concentrations of the metals in the leachate are measured using ICP-MS. In addition, the micro-leaching methodology devoted to the investigation of the structure of the slag surface layer before and after leaching is developed. Novel analytical techniques such as SEM/EPMA, TEM and XPS in combination with FIB and nano-characterization methods are implemented for analysis of the slag – aqueous solution interface. Understanding of dissolution of amorphous glass phase that is present in most existing metallurgical slags is a critical step to provide a link between the chemical and phase composition of slags at high temperature, the cooling regime and leaching phenomena.