Sustainable Recycling of EAF Steel Mill Dust - Waelz Process Vs. Other Technologies

oleh Dr. Juergen Ruetten , Ron Crittendon

Penerbit - ValoRes GmbH, Global Steel Dust

Kategori - Novel Am

Pyro-metallurgical processes like Waelz Kiln or Rotary Hearth Furnace are the most often applied technology for the recycling of dusty steel mill residues globally, especially for EAF and BOF dust. The target of the recycling process is to make the metals, which are containing in the residues, available for further re-use. The recycling of EAF dust closes the material loop between the steel and the zinc industry. More than 60 % of the produced zinc metal is used as corrosion protection agent on steel plates or structures. The steel at the end of its use is recycled as scrap in electric arc or induc tion furnaces for producing new steel. During this process the zinc coating is going to the dust. Nowadays still more than 50% of the generated dust is lost by sending it to landfill, which means an annual loss of more than 900,000 t of zinc. The paper gives an overview about all known recycling techniques for steel mill dust. The commercially applied pyro-metallurgical processes are compared under technical, economic and environmental aspects. The major processes in the comparison are Waelz Kiln, Rotary Hearth Furnace, Multiple Hearth Furnace and Shaft Furnace, but some other newly intro duced processes (e.g. the plasma and induction furnace) are also considered. The technical aspects high-lighten the raw materials and their preparation, the reducing agents, the consumption figures and the different products. The economic aspects concentrate on the operation costs. A state-of-the-art recycling plant fulfils all requirements for environmental protection. Some of the compared processes are listed in the BREF-Notes of the European Community. They can be operated free of wastewater, with low diffuse dust emission and with very low atmos pheric emission. The release of heavy metals or dioxin is well controlled by appropriate tech niques, which are also mentioned.

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