Research » Aluminum Recycling and Melt Purification
The working group focuses on the recycling of aluminium scraps via under salt or salt-free processes. Top Blown Rotary Converter (TBRC) in lab and demo-scale is used to perform the experiments. Efficient coagulation during recycling is also studied by using different salt compositions. In addition, thermal treatment of organic containing materials is being investigated to find an optimum process which is a combination of pre-treatment and recycling.
Moreover, the working group performs investigations about the melt cleanliness by using different removal and detection technologies to meet the high requirements of the product and material properties. Fundamental researches on particle behaviour in melts such as settling and agglomeration are also on-going to gain more knowledge about particles. Improvement of existing technologies and understanding of the mechanisms are main targets of the activities.
Contact:
Alumni:
- Dr.-Ing. Cong Li
- Dipl.-Ing. Jeraldiny Becker
- M.Sc. Tom Gertjegerdes
- Dr.-Ing. Mertol Gökelma
- Dr.-Ing. Songül Sieben geb. Gül
- Dr.-Ing. Regina Dittrich
- Dr.-Ing. Abyl Sydykov
- Dr.-Ing. Marion Thoraval
- Dr.-Ing. Marina Gnatko
- Dipl.-Ing. Maik Ridderbusch
- Dr.-Ing. Roger Sauermann
- Dr.-Ing. Tony Noll
- Dr.-Ing. Christoph Kräutlein
- Dr.-Ing. Katherina Jessen geb. Kaplan
- Dr.-Ing. Benjamin Jaroni
- Dipl.-Ing. Ursula Maiworm
- Dipl.-Ing. Traute Köther
- Dr.-Ing. Alf Niederle
Project List
Title
CO2-free aluminium production
Type
Verbundforschung
Sponsorship
Ministerium für Wirtschaft, Innovation, Digitalisierung und Energie des Landes Nordrhein-Westfalen
Duration
01.01.2022 – 31.12.2024
Partner
TRIMET Aluminium SE, Essen – Deutschland Plansee Verbundwerkstoffe GmbH, Lechbruck am See – Deutschland Universität des Saarlandes, Saarbrücken – Deutschland IME Metallurgische Prozesstechnik und Metal Recycling – RWTH Aachen, Aachen – Deutschland
Description
Approximately 21% of global greenhouse gas (GHG) emissions are caused by the industrial sector. Increasing concern about global climate change is leading many industries to pursue projects to reduce their “carbon footprint” in order to reduce their impact on the changing climate. Zero CO2 emissions in primary production is therefore the goal for the global aluminium industry. The aluminium industry has been working for decades to develop a CO2-free manufacturing process by replacing the horizontal carbon anodes in Hall-Héroult’s electrolysis cells operating at 960°C with inert non-carbon anodes, but without achieving any technical or commercial success, mainly due to material problems at this high operating temperature, impurities in the metal produced and increased energy consumption.
Title
Improvement of the energy and resource efficiency of the recycling of organically contaminated aluminium scrap
Type
Verbundforschung
Sponsorship
BMWi
Duration
05.2019 – 04.2022
Partner
IOB & IME (RWTH Aachen), Fricke und Mallah Technology GmbH, Hydro Aluminium Rolled Products GmbH , Otoo Junker GmbH, TRIMET Aluminium SE, WS Wärmeprozesstechnik GmbH (Deutschland)
Description
It is the goal to minimize the primary energy consumption and maximise metal yield by prozess optimization of combined thermal pre-treatment and melting of organic contaminated aluminium scrap. This is to be achieved by efficiently using the thermolysis gases of thermal pre-treatment, which has not been achieved by industrial processes, yet. The process optimisation is based on the fundamental investigation of a microwave rotary furnace for thermolysis of aluminium scrap, the development of a process control system for thermolysis gas combustion and the technical comparison of three industrial melting processes. With this process development and the generated data set, the transfer into pilot scale is possible after the project. The data set will be available for equipment manufacturers and industrial users, enabling industrial application and market-driven distribution.
Title
Techno-economic analysis of a reduction of the KCI content in the molten salt in the Al recycling
Type
No information
Sponsorship
AiF
Duration
01.12.2014 – 31.05.2017
Partner
K + S Entsorgung GmbH, Real Alloy Germany GmbH, Alustockach GmbH, Hydro Aluminium, Linde Ag, Lühr Filter GmbH, Marvo GmbH, Reinkalk GmbH, Bartz Maschinenbau GmbH, Lühr Filter GmbH-Deutschland
Description
Since no research center or company worldwide pursues this goal or develops or operates a similar process, the innovation potential of this process idea is obvious. The innovation, but at the same time the challenge here, is to maintain and even improve the necessary chemical-physical properties of the salt mixtures as the KCl content of the salt mixture is lowered. If this path leads to success, a reduction in production costs can be measured immediately.
Title
Impact of thermo-physical properties on three-phase-interactions of molten salt, liquid metal and non-metallic inclusions
Type
Grundlagenforschung
Sponsorship
DFG
Duration
01.11.2008 – 31.03.2012
Partner
Description
In metal winning and recycling processes like for Magnesium, Aluminium, even Copper or Zink molten salt fluxes , mostly containing KCl, NaCl and CaF2 are used. They have the role of separation of surface oxides, gases or other contaminations from metal as well as isolating the metal phase from the atmosphere. It is state of the art that application of salt flux in contact with contaminated raw materials like scrap leads inevitably to the formation of a salt-oxide-metal suspension, containing the both metallic and oxidized metal as well as salt components. Up to now it has not been yet possible to control this sludge formation in respect to metal losses and process feasibility.
Title
Investigation and evaluation of metallurgy for the internal recycling of fine-grained aluminum foundry material
Type
No information
Sponsorship
Otto Junker Stiftung
Duration
01.01.2010 – 30.06.2006
Partner
Gießerei-Institut RWTH Aachen-Deutschland
Description
The project aim is the detailed material balance and recording as well as evaluation of the melting metallurgy for foundries in crucible induction furnaces and in format casting foundries in induction furnaces and multi-chamber furnaces with Vortex and EMP for the recycling of internal aluminium machining chips. In addition, a distinction is made to other melting aggregates in which the aluminium cycle is recycled.
Title
Minimization of aluminum loss by avoiding wet-chemical salt slag preparation – production-integrated separation of the metal oxides and direct molten liquid reuse of the molten salt and re-use of the aluminum
Type
No information
Sponsorship
AiF
Duration
01.07.2006 – 31.06.2009
Partner
Purmetall GmbH, Metallhüttenwerke Bruch, Aluminiumschmelzwerk Oetinger GmbH, ScholzAlu Stockach GmbH, Thermo-Star GmbH-Deutschland
Description
The primary aim is to achieve a cost saving potential by shortening the process chain and increasing the salt and aluminium yield of the overall process. From a scientific-technical point of view, the project represents the development and testing of a process with the aid of published laboratory results for various individual process steps. The research project is aimed at the development of a process for the direct or integrated recycling of salt slag in the molten state and the recycling of the metal and salt contents of the salt slag in liquid form into the cycle as well as their testing of the process on a pilot scale.
Title
Refining of aluminum alloys – Equilibria and kinetics of crystallization of intermetallic compounds from Al-Si-Fe-X melts (X: Mg, Mn, Ti)
Type
No information
Sponsorship
DFG
Duration
01.08.2005 – 31.08.2008
Partner
Hydro Deutschland-Deutschland, Institut National Polytechnique de Grenoble-Frankreich, Institut für Stähle und Legierungen (MISIS)-Russland
Description
The aim of the project is to demonstrate a crystallization process for the purification of ferrous multi-component Al casting alloys from Fe, Mn, Mg, Ti by intermetallic precipitation. In particular, the interaction with the alloying element silicon will be investigated.
Title
MOLTEN ALUMINIUM PURIFICATION – Purification by formation and removal of inter-metallics
Type
No information
Sponsorship
EU
Duration
01.05.2002 – 30.04.2006
Partner
Alcan International Ltd.,MIRO Minerals Industry Research,SINTEF,Norsk Hydro ASA,Remi Claeys Aluminium,VITO-Process Technology Group,Centre de Recherches de Voreppe,LTPCM,VAW AluminiumAG,CORUS Research
Description
In aluminium production Fe, Si and Mn are common sources of contamination. It is possible to remove these contaminations by the active formation and subsequent removal of inter-metallics. To make this process economical the inter-metallic formation should be optimized by the addition of extra trace elements. A systematic experimental search program will be carried out to find the economically optimal additives. The subsequent removal stage requires very accurate temperature control and the development of an advanced aluminium filtration technology such as displacement washing. These developments will be undertaken at lab-scale, and then scaled-up. The final result of the project will be a semi-continuous in-line filtration module for the removal of Fe, Si and Mn at a cost of less than 200 USD/t. The technology will be applicable in a typical aluminium casthouse, for instance between the melting and casting furnace.
Title
Systematic investigation of the influencing variables for the optimization of the metal waste yield during the salt melting of aluminum scrap
Type
No information
Sponsorship
AiF
Duration
01.10.2001 – 31.12.2003
Partner
Brinker Aluminium-Schmelzwerk GmbH, Aluminiumschmelzwerk Oettinger GmbH, Metallhüttenwerke Bruch GmbH-Deutschland
Description
The melting of heavily contaminated or finely divided scrap often takes place under a salt bath, which usually consists of NaCl, KCl and fluoride salt additives. In Germany, smelting salts based on a salt mixture of approx. 70 % NaCl and approx. 30 % KCl are most frequently used. The used fluoride salts are mostly CaF2 and rarely cryolite. There are few investigations which refer to this base salt mixture. Therefore, the properties of the melting salt and their influence on the melt yield when melting aluminium scrap were investigated in this paper. In the literature, the basic properties of the melting salt, such as density and surface tension as a function of temperature, CaF2- and Na3AlF6- concentration, are not available. To fill this gap, they were measured in this thesis.
Title
New process for melting very finely divided aluminum precursors which are difficult to process, as well as checking the transferability of the process to magnesium precursors
Type
No information
Sponsorship
BMBF
Duration
01.09.2004 – 30.06.2006
Partner
Konzelmann Metallschmelzwerke-Deutschland
Description
The aim of the current project is the development of a melting method for finely divided aluminium residues, which ensures a high yield of aluminium as well as minimising the amount of salt slag. The new process is based on the continuous melting of fine-particle Al precursors under large excess salt (ideal conditions) and on the simultaneous separation of the oxides from the molten salt slag by means of an immersion centrifuge. Instead of a liquid salt slag, a residual filter mass with oxide contents of up to 60 % is produced. This reduces the need for salt and the amount of salt slag. Furthermore, a much more liquid salt bath (hardly any oxide content) keeps fewer Al droplets in suspension, which drastically reduces metal losses. Since filter residues or conventional salt slags are generally leached during processing under conditions in which metallic Al oxidizes, power losses can be minimized.
Title
Development of recycling concepts for the processing and utilization of scrap from aluminum special materials (aluminum foams, special alloys, metal composites, iron-containing scrap)
Type
No information
Sponsorship
BMBF
Duration
01.10.2004 – 30.09.2007
Partner
VAW-IMCO Guss und Recycling GmbH Grevenbroich
Description
The overall objective of the project is the development of recycling concepts for the processing and utilisation of scrap from special aluminium materials (aluminium foams, Al-Fe and Al-Mg composite materials and the cleaning of Al melts from Pb, Sn, Sb, Li and Cd). Due to their content of alloying elements or built-in parts, these cannot currently be incorporated into the existing recycling concepts of the aluminium cycle, as they can have a negative effect on the quality of the secondary alloys. The results of the research and development work will be made available to the industry, in particular to the German-based recyclers of aluminium scrap (smelters, remelters), following a positive course of the project.
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