Recycling and Sustainability in Cast Shop Technology: Joint Session with REWAS 2022: Recycling and Sustainability Joint Session with REWAS 2022
Sponsored by: TMS Extraction and Processing Division, TMS: Recycling and Environmental Technologies Committee, TMS: Aluminum Committee
Program Organizers: Mertol Gokelma, Izmir Institute of Technology; Stephen Instone, Speira Gmbh
Tuesday 2:30 PM
March 1, 2022
Room: 209A
Location: Anaheim Convention Center
Session Chair: Rauan Meirbekova, DTE
2:30 PM Introductory Comments
2:35 PM
Effect of Compaction and Thermal De-coating Pre-treatments on the Recyclability of Coated and Uncoated Aluminium: Alicia Vallejo Olivares1; Solveig Høgåsen1; Anne Kvithyld2; Gabriella Tranell1; 1Norwegian University of Science and Technology; 2SINTEF
Scrap pre-treatments, such as compaction and thermal de-coating, are standard industrial practices for recycling aluminium post-consumer scrap. This study compares the recyclability of a coated and uncoated 8111 alloy under the application of compaction and/or thermal de-coating pre-treatments. Sheets of 600 μm thickness were shredded into chips and compacted by uniaxial pressure, moderate pressure torsion (MPT) or MPT at 450 °C (Hot MPT) into briquettes of 4 cm diameter. A subset of briquettes and loose chips was subsequently heat-treated for 1 hour at 550 °C, while the other set was left untreated. The effectiveness of the heat-treatment for the different compaction methods was examined by mass balance and the internal porosity of the briquettes by computed tomography. Re-melting the samples under molten salt-flux showed that the coalescence of the coated material significantly improves with the thermal de-coating pre-treatment, especially for the loose chips and briquettes compacted uniaxially. Lower coalescences were obtained for the de-coated MPT briquettes, as a result of an incomplete de-coating.
2:55 PM
Innovative Utilization of Aluminum-based Secondary Materials for Production of Metallurgical Silicon and Alumina-rich Slag: Harald Philipson1; Gjermund L. Solbakk1; Maria Wallin1; Kristian Etienne Einarsrud1; Gabriella Tranell1; 1Norwegian University of Science and Technology
The SisAl process encompasses the production of metallurgical silicon (Si) by reducing silica-based secondary raw materials aluminothermically. Along with the Si-alloy, a CaO-Al2O3-(low)SiO2 slag is produced, an appealing product particularly for the alumina industry. The research aims to explain key aspects of aluminothermic reduction to facilitate upscaling and combining optimal Si- and Al2O3-yield. Three size fractions of aluminum (Al) dross were reacted with pre-fused CaO-SiO2 slag or Si-refining sculls at 1650 °C or above in two induction furnaces with different size and atmosphere. Supported by thermodynamic calculations, CaO/SiO2 ratio and reductant to silica-based slag ratio were varied and related to Si-yield and slag quality.The results show that the Si-alloy is rapidly produced, and the Si-yield depend on the separation ability of alloy and slag. Al-dross and Si-refining sculls were found to be suitable for the SisAl process, enabling a circular economy perspective on these secondary streams.
3:15 PM
Use of Incinerator Bottom Ash (IBA) in Aluminium Recycling: Martin Syvertsen1; Thomas Ludwig2; Snorre Rist2; Kjerstin Ellingsen1; 1SINTEF Industry; 2Hydro Aluminium
Incinerator Bottom Ash (IBA) originates from incineration of municipal waste. The waste contains a fraction of metal where some is aluminium. Unless proper treatment, the bottom ash ends up either in landfills or in best case as building material. Aluminium recovered from IBA can be recycled and used as a material in aluminium production. This paper describes characterisation of a typical big-bag of recovered aluminium recovered delivered to the aluminium industry. The big-bag contained 500 kg of recovered aluminium in the form of lumps with sizes between 5 and 50 mm. The content was split and sieved into 5 size classes. Each size class was remelted with salt, and the oxide content and chemical composition was determined. It was found that both oxide content and alloy composition varied between the size classes. This should be taken into account when the IBA is used as charge material.