STABILIZATION OF TOXIC COMPOUNDS OF ELECTRIC ARC FURNACE DUST BY PRODUCTION OF GLASS-CERAMIC

Due to presence of toxic compounds, steel manufacturing furnace dust (EAFD) is causing environmental pollution especially ground water cycle, so toxic elements should be stabilized beforethese dusts are landfilled. In this research work, production of glass and glass ceramic from EAF dustwith regard to stabilization of toxic elements was investigated. Mixture different amounts of EAF dust was with silica sand, sodium carbonate and calcium oxide were melted and casting in steel molds.Mixing of these materials based on ternary diagram CaO-MgO-Al2O3-SiO2 was chosen so that themixture is in the range of glass formation. Glass produced by appropriate heat treatment has become to glass-ceramic. Produced glass-ceramic was investigated with the view of stable compounds,microscopic structure and mechanical properties. By thermal analysis (differential thermal analysis) suitable conditions of heat treatment were determined to get appropriate microscopic structure and mechanical properties. With elemental analysis (EDAX), the distribution of elements of the produced glass-ceramic was investigated. Leaching tests were performed to investigate the stability of thecompound according to EPA standard. Leaching experiment showed that produced glass-ceramic was very stable chemically and ions emission in solution with pH= 5 was about zero. The dominant phase in almost samples was wollastonite. SEM images taken from the samples of glass ceramic showed that the overall shapes of crystals in glass are dendritic. By applying heat treatment, hardness of glass ceramics are significantly reduced and their mechanical strength is extremely increased. Glasses production have average 800 Vickers microhardness and after heat treatment that its value reduced to an average of 500 Vickers.

Keywords:

heavy metals , glass-ceramic