Abstract
Electric arc furnace dust from steel production is generated in considerable amounts worldwide and needs to be treated as hazardous waste. The aim of this study was to investigate the properties of electric arc furnace dust solidified/stabilized by using Portland cement. Mortar and paste samples were prepared with varying waste-to-binder ratios between 0% and 90%. A comprehensive experimental program was designed including XRF characterization, setting time, unconfined compressive strength, and toxicity characteristics leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), and acid neutralization capacity (ANC) tests. The results were evaluated in order to determine if the solidified /stabilized product can be disposed of at a landfill site with domestic waste or at a segregated landfill. The effect of using sand on S/S performance was also investigated. The results indicated that the solidification /stabilization process using PC helps the heavy metals to be bound in the cement matrix, but the TCLP leaching results exceeded the EPA landfilling limits. The SPLP leaching results conformed to the limits implying that the waste or S/S products can be disposed of at a segregated landfill; however the low ANC of the S/S products reveals that there may be leaching in the long-term. The sand used in the mortar samples adversely affected the S/S performance, causing higher heavy metal leaching levels, and lower pH levels in the leachate after the TCLP extraction than those measured in the leachate of the paste samples.
Extracts
Electric arc furnace dust (EAFD) is generated in considerable amounts by the electric arc steelmaking process. During melting in an electric arc furnace, certain elements volatilize, and after cooling, these elements form a fine dust. This dust, called EAFD, is collected in a baghouse and amounts to approximately 2% of the steel produced (AISI, 2001). In Turkey 20.961 million tons of steel was produced in 2005 (IISI, 2006) with 64% of plants equipped with electric arc furnaces (Orhan, 2005), generating 268,300 tons of electric arc furnace dust in Turkey in 1 year.
The chemical composition of EAFD was investigated by several researchers, and the most abundant heavy metals in EAFD were found to be Zn, Pb, Cr, and Cd (Pereira et al., 2001; Pelino et al., 2002; Sofilic et al., 2004; Orhan, 2005). Because of the leaching potential of the heavy metals it contains, EAFD has been designated by Turkey, the European Union (EU), and the EPA (United States Environmental Protection Agency) as a hazardous waste, which means that it cannot be disposed of at landfills without treatment.
... EAFD can vary greatly in composition depending on the composition of the scrap charge, the furnace additives used, and the type of steel being manufactured. For example, use of galvanized steel scrap would increase the zinc content in the EAFD. Zinc content in EAFD may vary between 7% and 40%, and lead content between 4–9% (Orhan, 2005). ...
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