Characterization and pre-treatment of steelmaking dusts in order to recover valuable products

Steelmaking dusts are frequently classified as hazardous residues, due to their eco-toxicity characteristics. This derives mainly from the presence of heavy metals like zinc, lead and cadmium in their compositions, in forms that are easily leachable by water or slightly acidic or alkaline media. Following the most employed eco-toxicity standard tests, like DIN 38414-S41) from Germany, and TCLP (Toxicity Characteristic Leaching Procedure)2) from the United States, steelmaking dusts present a high level of mobility of heavy metals, what is relevant for the evaluation of their environmental impact, when disposed in controlled landfills. By this work, financed by the European Communities COPERNICUS Programme, a characterisation of the dusts generated in different steelmaking plants has been done. Also, the behaviour of the dusts when washed with cold water has been evaluated, giving some informations on the mobility of metals and on the prospects for pre- treatment of the residues to recover valuable products