Evaluierung des Brennstoffeinflusses beim Schmelzen verunreinigter Schrotte mit Salz

Translated title of the contribution: Evaluation of the influence of fuel when melting contaminated scrap with salt

Research output: ThesisMaster's Thesis

Abstract

As part of a project to achieve climate neutrality, the use of alternative, emission-free heating concepts in smelting furnaces for contaminated aluminum scrap is being evaluated. The use of hydrogen burners instead of conventional natural gas burners is proving to be particularly promising in this context. However, a conversion inevitably leads to a change in the atmosphere in the tilting drum furnaces. In addition to the elimination of fuel-related CO2 emissions, an increase in the water vapor content is to be expected. The H2O concentration in the furnace atmosphere theoretically increases from 67 % by volume to 100 % by volume when hydrogen is burned instead of natural gas. The extent to which such a change affects the melt quality, the metal yield and the properties of the salt slag has not yet been investigated. In order to evaluate this, several scrap batches of 10 kg each are melted with melting salt in a laboratory tilting drum furnace based on industrial aggregates. The burner used has a rated output of 30 kW and can burn both methane, the main component in natural gas, and hydrogen with oxygen. The charge comprises a mixture of capsule strip, sheet scrap of alloy class 5xxx and magnesium-rich dross. The density index is used to assess the quality of the melt. In addition, a detailed mass balance including preparation of the salt slag provides information on the melting yield and oxidation losses. It can be seen that the use of hydrogen as a fuel tends to increase the density index. This is presumably due to an increase in the hydrogen content in the liquid metal. Furthermore, the metal yield is on average 9.4 % higher compared to the natural gas tests. The potential cause of this is a significantly shorter melting or batch duration with identical burner output. This suggests a change in heat transfer in the furnace. The improved yield is due to a 7.0 % lower metal content in the salt slag and a 2.4 % reduction in oxidation losses. These observations show that it is basically possible to convert the heating concept in these furnaces to hydrogen burners as part of the decarbonization process. However, various aspects, such as heat transfer in the furnace and potentially altered gas formation properties of the salt slag formed, still need to be analyzed in further studies.
Translated title of the contributionEvaluation of the influence of fuel when melting contaminated scrap with salt
Original languageGerman
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Tichy, Stefan, Co-Supervisor (internal)
  • Antrekowitsch, Helmut, Supervisor (internal)
Award date28 Jun 2024
Publication statusPublished - 2024

Bibliographical note

embargoed until 17-05-2029

Keywords

  • hydrogen
  • decarbonisation
  • aluminiumrecycling
  • tilting drum furnace
  • density index

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