Treatment of inorganic hazardous waste constituents found in electric arc furnace dust by solidification/stabilization
Moore, Tiffany Len
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In this study, solidification and stabilization processes were evaluated for use as a treatment method for electric arc furnace dust. Specific objectives were (1) to develop a solidified material capable of meeting EPA requirements for heavy metal leaching, and (2) to develop a solidified material that could be used for construction. Results from the studies of the untreated electric arc furnace dust showed that the solubility of cadmium is controlled by the hydroxide species. Lead solubility is more complex because its solubility is controlled by a species other than hydroxide and therefore it is more difficult to predict. Studies also indicated that approximately 1.9% of the composition of the electric arc Furnace dust is made up of lead. This study demonstrated that solidification and. stabilization is a viable treatment process for electric arc. furnace dust. Success in treating the electric arc furnace dust by this method, however, depends upon such factors as the compressive strength of the solidified waste, the amount of electric arc furnace dust incorporated in the concrete, and the ability of the solidified waste to remain intact during the Toxicity Characteristic Leaching Procedure (TCLP). Based on these factors, approximately 165 lb dust/cu yd concrete was determined to be the upper limit on the amount of electric arc furnace dust that can be incorporated in such a system. Efforts to improve the quality of the concrete by the addition of a chelating agent was moderately successful; however, the addition of salts to speed the concrete set times was not successful. A model was developed which predicts the required compressive strength of the solidified dust based upon the amount of electric arc furnace dust that is incorporated in the concrete. The model effectively predicts, without performing the TCLP test, whether the solidified material will meet limits for heavy metal required by the EPA.
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