Abstract
Steel-making slag is largely used today in road construction and other applications, but significant volumes are landfilled and cannot be recycled for excessive contents in hazardous metals, such as chromium or vanadium. The long-term behaviour of this material is still little known, and the characterisation of large volume slag dumps remains an environmental challenge. In this study various analytical techniques are used to characterise Electric Arc Furnace (EAF) slag landfilled for several decades and exposed to chemical weathering and erosion. Coupling chemical, mineralogical and magnetic techniques helps to understand the relations between hazardous metals and mineral phases. A special interest is given to Fe-bearing minerals microstructure so as to link the magnetic properties of the material to its mineralogical composition. The studied slag presents high amounts of chromium (between 1 and 3 wt. %) and very high magnetic susceptibility values (near 60 × 10−6 m3/kg), explained by the presence of magnetite and a spinel solid solution. Some correlations are found between magnetic susceptibility and potentially hazardous metals, providing new perspectives for future environmental investigations.
Highlights
IntroductionAn important part of this slag can be recycled as aggregates for road construction, as additives in cement and concrete production, as fertilizers and various others uses, but between 1 and 4 million tonnes per year are landfilled
More than 400 million tonnes of iron and steel slag are produced each year in the world [1,2].In Europe, about 18 million tonnes of steel slag were produced each year from 2000 to 2016 [3].An important part of this slag can be recycled as aggregates for road construction, as additives in cement and concrete production, as fertilizers and various others uses, but between 1 and 4 million tonnes per year are landfilled
The present study focuses on partially weathered Electric Arc Furnace (EAF) slag coming from the steel-making plant of Châteauneuf (Loire, France)
Summary
An important part of this slag can be recycled as aggregates for road construction, as additives in cement and concrete production, as fertilizers and various others uses, but between 1 and 4 million tonnes per year are landfilled. This part remains unusable because of the presence of potentially hazardous metals. Electric Arc Furnace (EAF) slag, which present high contents in chromium (Cr), vanadium (V) and molybdenum (Mo), often fall into that category. They result from recycled steel scrap melting and represent between 30% and 40% of the total steel-making slag production.
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