نثبيت تركيبات سمي موجود در غبار كوره قوس الكتريك توسط توليد شيشه سراميك

چكيده انگليسي :

Stabilization of compounds materials in electric arc furnace dust by production of glass ceramic Ahmad Nazari Ahmad Nazari65@gmail com 9 18 2012 Department of Materials Engineering Isfahan University of Technology Isfahan IranDegree M Sc Language FarsiAbstractDue to the presence of toxic compounds steel making dust EAFD is causingenvironmental pollution especially in ground water cycle So toxic elements should bestabilized before these dusts are landfilled In this research work production of glass andglass ceramic from EAF dust with regard to stabilization of toxic elemnts was investigated Different amounts of EAF dust was mixed with silica sand sodium carbonate and calciumoxide and were melted and casted in steel molds Mixing of these materials were chosenbased on ternary diagrams of CaO MgO Al2O3 SiO2 Sodium carbonate was added to themixture in order to reduce the melting temperature of the mixture and increase theviscosity the melt Appropriate heat treatment were applied to the casted glass to produceglass ceramic Produced glass ceramic was investigated from the view of stablecompounds microscopic structure and mechanical properties By thermal analysis differential thermal analysis suitable conditions of heat treatment were determined to getappropriate microscopic structure and mechanical properties for nucleation of crystallinephases in produced glass two stage and single stage heat treatment were applied In thefirst stage of two stage heat treatment small and stable nucleations of ceramic crystals areformed in preferred locations Preferred locations for nucleation of crystalline phase areinterfaces or free surfaces In the second stage of two stage heat treatment growth ofcrystal nucleations are occured and in single stage heat treatment the nucleation andgrowth of ceramic crystals are occured simultaneously Leaching tests were performed toinvestigate the stability of the compound according to Environmental Protection Agency EPA standard The leaching tests on electric arc furnace dust showed that amount of Znand Cd exceeded from extent permitted also the leaching tests on glass and glass ceramicshowed that produced glass and glass ceramic were chemically very stable and ionsemission in solution with pH 5 was about zero The x ray diffraction studies on producedglass ceramics indicated that The dominant phase in most samples was wollastonite Scaning electron microscopic images taken from the samples of glass ceramic showed thatthe overall shape of crystals in glass ceramic are dendritic and with increase in amount ofdust in the initial mixtures the crystalline phases increases By applying heat treatment hardness of glass ceramics were significantly reduced and their mechanical strength wasextremely increased Produced glasses had average 800 vickers microhardness and afterheat treatment its value reduced to 500 vickers and it was observed that with increase inamount of electric arc furnace dust in the initial mixture the micro hardness of glassceramics severely reduced When 30 wt EAF dust was used in the initial mixture glassceramic with highest mechanical property was obtained Key words electric arc furnace dust heavy metals glass ceramic

نظري، احمد

نثبيت تركيبات سمي موجود در غبار كوره قوس الكتريك توسط توليد شيشه سراميك

فلزات سنگين