Paper Title
Valorization Of Steel Slag In Road Construction - Comprehension Of Molybdenum’s Repartition

Abstract
Steel production in an electric arc furnace (EAF) generates a by-product called EAF slag. As a result of the presence of significant amounts of impurities, EAF slag is generally not or less recycled in a next steel production and stored in the form of a dump which takes increasingly space. Many studies have shown that slag may substitute for natural aggregate in the construction sector. In which case, the use of slag cannot expand because some slags may contain traces of leachable heavy metals, which are considered as potential threats to human health and environment. In the present study, the slag sample was collected from an historical slag dump disposed for about sixty years. We decided to investigate the repartition molybdenum (Mo), a heavy metal much used in the recent steel production and still detected in slag. In addition to the determination of main chemical and mineralogical compositions by X-ray fluorescence (XRF) and X-ray diffraction (XRD), cathodoluminescence (CL), scanning electron microscopy (SEM) and micro fluorescence (µ XRF) were used to understand the repartition of Mo in the different phases of slag. The results indicate that Mo were localized in two phases: iron silicates (FexSiyO4) and melilite (solid solution of akermanite (Ca2MgSi2O7) and gehlenite (Ca2Al[AlSiO7])). Index terms- EAF steel slag, leaching test, petrography