Immobilization of electric arc furnace dust toxic elements within the matrix of concrete based products

Abstract

Electric Arc Furnace Dust (EAFD) generated through the production of carbon and alloy steel products is classified as environmentally hazardous waste mainly because of its relatively high levels of Pb, Cd and Cr. The aim of the present work was to investigate the effect of the EAFD addition on the properties of concrete building products (e.g concrete bricks) and to stabilize the toxic elements contained in EAFD in order to get environmentally accepted products. Concrete specimens were prepared by vibration and press-forming of mixtures containing cement, sand, dolomite, calcium stearate with water and the addition of different percentages of EAFD. For the immobilization of the toxic elements of EAFD within the matrix of the specimens, different percentages of each one of NaH2PO4, H3PO4 and of a mixture of H3PO4 - FeSO4.7H2O were added successively to each one of the mixtures as stabilizing materials. Modulus of rupture (MOR) and water absorption (WA) tests showed that the specimens produced had specifications within accepted limits for relevant products. Leaching tests applied on the specimens proved the compliance with imposed leachate Maximum Acceptable Limits (MAL), since the practiced stabilizing materials effectively immobilize toxic elements within the prepared specimens. © 2010 Global NEST.