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For the processing of metals and their oxides there is always the problem of residual materials like dusts or sludges. Because of that, environmental concerns become more and more important to the government and to companies. Due to changes in environmental laws, the disposal of process residues becomes more challenging and more expensive. This is the reason why inertisation of hazardous materials and the fabrication of saleable products get more interesting for the metal industry.
The amount of steels with surface treatment is rapidly increasing worldwide. For improving the corrosion resistance the utilisation of zinc is common in the steel industry. At the end of the product lifecycle coated steels can be recycled in EAF as secondary raw material or in the BOF for cooling. Therefore the recycling of steel mill dusts closes the loop between steel and zinc industry. For the recycling of these materials the Waelz rotary kiln process is the state of the art technology and known as best available technique (BAT) in the European Union. For the recycling of steel mill dusts in the Waelz process, several specifications of the dust are necessary. In addition pretreatment facilities and additions are needed.
A new technology for the recycling of steel mill dust is the RecoDust process, which is the only process not needing any pretreatment steps. The steel mill dust fines can be processed just in the same condition as they exit the baghouse filters of the dedustig unit. The large range of processable dusts, especially dusts with low zinc content, is another feature of this technology. The only requirement for the processing in the Flash-Reactor is a dry and free-flowing dusty input material. The RecoDust process can be realised in a single step process with reducing conditions in the reaction vessel and a double step process with oxidising conditions in the reaction vessel and a downstream inductive heated coke bed. Right now only the single step process is realised.
|Copyright:||© Lehrstuhl für Abfallverwertungstechnik und Abfallwirtschaft der Montanuniversität Leoben|
|Source:||Depotech 2012 (November 2012)|
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