Verwertungsstrategien für Reststoffe aus der Aluminiumsekundärmetallurgie

Translated title of the contribution: Recycling strategies for residuals from the secondary aluminium metallurgy

Helmut Paulitsch

Research output: ThesisDoctoral Thesis

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Abstract

Due to the high affinity to oxygen dross is generated during the recycling process of aluminium. This residue contains high contents of metallic aluminium, so that the recovery method is economic. The dross has also to be treated in view of ecological impacts. The most frequently technologies for the recycling of this residue are a melting process with salt in a rotary drum or a tilting furnace and mechanical methods. Particularly with regard to smaller secondary aluminium smelters which don’t have their own in-house recycling process the dependence of the drum furnace operator decreases by the implementation of such conditioning process. The mechanical dross processing consists of crushing, milling and screening steps. The advantage of this method is that there is no salt slag formed which has to be disposed. In Austria the landfilling of this residue is not allowed and there is no salt slag processing plant for treating this material. The disadvantage of the mechanical technology is the arising of the reactive dross dust. This residue reacts with the moisture by emitting ammonia gas and hydrogen. During landfilling of the dross dust some substances are eluted which are polluting the groundwater. To ensure the sustainability the material has to be treated for inertisation and as an ancillary effect for winning some by-products. Also the salt slag, which is accumulated at the rotary drum and tilting furnace has to be processed. There are some hydrometallurgical technologies for treating this residue. For the rotary drum operators it is also possible to optimize the treatment process for the salt slag after skimming. The state of the art is to cool down the residue under atmospheric conditions. The containing metallic aluminium partially reacts during this process with the oxygen so that it is lost for the salt slag recycling process. A new technology is to cool down the salt slag under defined conditions as fast as possible under a critical temperature where the oxidation process stops. Due to the higher aluminium content of the slag, which is delivered to a conditioning plant, the recycle flow of the metal is higher. As a result of this the profit increases. The driving force for the recycling of residues from the secondary aluminium industry are ecological and socio-political aspects as well as the legislation. The mentioned treatment processes have to be Zero-Waste-Technologies. Under consideration of the sustainability the dross processing technologies have to be methods, where all of the emitted residues have to be completely recycled. In this context the determination of the material flow as well as the characterization of the residues are required for the ecological implementation of the recycling technologies.
Translated title of the contributionRecycling strategies for residuals from the secondary aluminium metallurgy
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Kepplinger, Werner Leopold, Assessor B (internal)
  • Antrekowitsch, Helmut, Assessor A (internal)
Publication statusPublished - 2012

Bibliographical note

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Keywords

  • dross
  • mechanical and pyrometallurgical dross processing
  • dross residue
  • dross dust
  • zero-waste
  • characterisation
  • REM
  • LIMI

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