Vitrification and Sinter-Crystallization of Iron-Rich Industrial Wastes

Results about the vitrification of several hazardous iron-rich industrial wastes (from productions of Zn and Cu metals, as well as EAFD and MSWA) and the usage of obtained glasses for synthesise of sintered glass-ceramics are summarises. It is shown that the appropriated method of sinter-crystallization mainly depends on the crystallization trend of used glasses. When the parent composition is characterised by formation of a moderate amount of crystal phase low temperature sintering with short crystallization step in the interval 800-900 o C can be used. In addition, attractive granite-like building glass-ceramic can be obtained by mixing fine and coarse glass frits and “free” sintering in refractory moulds at 1000-1050 o C. Contrary, when intensive phase formation carries out the crystallization inhibits the sintering resulting in specimens with scarce degree of densification. However, in some cases a secondary densification process occurs at temperatures near to the eutectic ones, leading to well sintered samples with higher crystallinity and improved mechanical properties. It is also highlighted that the preventing of Fe 2+ oxidation by using inert atmosphere during the heat-treatments leads to a decreasing of sintering temperature, finer crystalline structure and additional enhancement of the mechanical properties.