Immobilization of iron rich steel industry waste and products characterization

• Fine dust with high iron content has been vitrified by mixing with recycled glass.
• Varying the dust/glass ratio, glassy or glass–ceramic materials are produced.
• Leaching test values are under regulation limits, proving the chemical durability.
• The glass–ceramic products show a ferromagnetic behaviour.
• Iron rich samples show low electrical resistivity.

The steel industry produces large amount of wastes, some of which are today used in other industrial sectors; iron oxide rich wastes are difficult to recycle and vitrification is one of the most efficient techniques to stabilize them and produce materials suitable for new applications. The waste considered in this study comes from the purification of fumes captured by hoods during agglomeration process in the sinter plant. These dusts have been vitrified on a laboratory scale by the addition of glass cullet coming from diversified harvest of municipal waste, varying the glass/dust ratio from 80:20 to 50:50. The as produced materials have been characterized by means of XRD analysis and SEM images, and leaching tests have been carried out to evaluate their chemical stability. The electrical and magnetic properties of these iron rich materials have been evaluated too. The resistivity of the samples produced with 45% and 50% of waste are 20 and 1.5 × 103 Ω m respectively, considerably lower than the common soda-lime glass resistivity value (1012 Ω m). Moreover the materials show a ferromagnetic behaviour; the Curie Temperature of the materials lies in the range from T = 395 °C to T = 533 °C, confirming the presence of magnetite/maghemite phases.