Influence of Na_2O/Al_2O_3 and SiO_2/Al_2O_3 ratios on the immobilization of Pb from electric arc furnace into the fly ash based geopolymers

摘要

Electric arc furnace dust (EAFD) is by-product of iron and steel scrap remelting in electric arc furnace. This waste is classified as a hazardous material due to the leaching of heavy metals into the environment. Geopolymeryzation of fly ash into construction materials called - geopolymer is a considering as a possible way of immobilization of heavy metals from EAFD. Mechanical properties and chemical stability of geopolymers are mostly determined by the ratio between main oxides, Na_2O, Al_2O_3 and SiO_2. In this paper we have investigated possibility of Pb immobilization from EAFD into the fly ash based geopolymer. Geopolymers are synthesized at different Na_2O/Al_2O_3 and SiO_2/Al_2O_3 ratios. Compressive strength and chemical stability of geopolymers with respect to the leaching of Pb in water according to the EN 12457 regulation were tested. The results have shown that Na_2O/Al_2O_3 and SiO_2/Al_2O_3 ratios have influence on the compressive strength of geopolymers and Pb release in the water environment.