Transforming electric arc furnace waste into value added building products

Abstract

Electric Arc Furnace dust is an abundant hazardous by-product of EAF steelmaking which poses significant environmental challenges for disposal given the presence of high concentrations of heavy metals which can leach into groundwater or contaminate soil when landfilled. This study proposes a novel new process to safely transform electric arc furnace dust into value-added building materials by combining it with blue shale to produce high strength lightweight aggregates. Both materials were characterised elementally and thermally by X-ray fluorescence and differential scanning calorimetry-thermal gravimetric analysis. Dilaotmeter study proved that addition of electric arc furnace dust to blue shale resulted into lower softening temperatures and addition of 5 wt% of electric arc furnace was found to be appropriate as 10 wt% addition showed no bloating behaviour. Light weight aggregates with 0 and 5 wt% electric arc furnace dust were sintered to different temperatures for different holding times. The results revealed that increased sintering temperature and holding time resulted in more porous structure in light weight aggregates with electric arc furnace dust, compared to the samples without electric arc furnace dust. This was observed closely via scanning electron microscope images. The study concluded that the sintering of blue shale with 5 wt% electric arc furnace dust at 1150 °C for 5 min Produced the highest compressive strength (8.25 MPa) with a moderately low density (1.76 g/cm3). The resulting light weight aggregate showed negligible leaching of heavy metals when tested, due to their stabilisation in the crystalline ceramic phase during high temperature sintering. Electric arc furnace dust was confirmed as a potentially valuable input in the production of non-toxic, high performance building materials.