Cast Shop Technology: Furnace Operations and Recycling
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Halldor Gudmundsson, Century - Nordural; Stephan Broek, Kensington Technology Inc
Tuesday 8:00 AM
March 21, 2023
Room: 31C
Location: SDCC
Session Chair: Luke Mackenzie, HATCH
8:00 AM
Hydrogen Absorption of Aluminum-magnesium Melts from Humid Atmospheres: Stefan Tichy1; Philip Pucher2; Bernd Prillhofer2; Stefan Wibner1; Helmut Antrekowitsch1; 1University of Leoben; 2AMAG casting GmbH
In casthouses, water vapor has long been considered a source of high hydrogen contents in aluminum melts. Moisture levels are usually highest in melting and holding furnaces, where H2O contents of up to 18 vol.% occur due to the combustion of natural gas with air. In the case of oxyfuel burners, contents of even more than 60 vol.% are theoretically possible. To avoid defects such as annealing bubbles or grain porosity in the subsequent production steps, the absorbed hydrogen must be reduced to a minimum by degassing treatments. To gain a better understanding of the interaction between liquid aluminum and water vapor, the hydrogen absorption of aluminum-magnesium melts under atmospheres with varying water vapor contents of 0-90 vol.% at around 700 °C (1300 °F) is investigated in this work. Furthermore, the influence of H2O on the oxidation behavior is also examined.
8:25 AM
Influence of Cryolite Content on the Thermal Properties and Coalescence Efficiency of NaCl-KCl Salt Flux: Veronica Milani1; Alicia Vallejo Olivares2; Gabriella Tranell2; Giulio Timelli1; 1University of Padova; 2Norwegian University of Science and Technology
Salt fluxes with fluoride additions are necessary to treat contaminated or oxidized aluminum scrap. This study aims to investigate the effect of cryolite additions on the thermal properties and the coalescence efficiency of a NaCl-KCl salt flux mixture. Thermodynamic calculations were carried out to examine the phase diagram of the salt mixture as the cryolite content increases. The study of the melting properties of the salt was carried out by means of differential scanning calorimetry. The coalescence efficiency of the salts was assessed by re-melting coated aluminum shredding. The results show a decrease of the melting point as the cryolite content increased, in good agreement with the thermodynamical calculations. For cryolite contents up to 3% wt., higher cryolite content in the salt leads to higher coalescence of the remelted shredding. However, the effects of increasing the cryolite content further than 3% wt. are minor.
8:50 AM
Oxidation Study of Al-Mg Alloys in Furnace Atmospheres Using Hydrogen and Methane as Fuel: Martin Syvertsen1; Anders Johansson2; Johannes Lodin3; Are Bergin4; Mari Ommedal5; Yngve Langsrud6; Ray Peterson7; 1SINTEF Industry; 2Siemens Energy AB; 3Linde Gas AB; 4Hydro Aluminium ANS; 5Alcoa Norway ANS; 6Benteler Aluminium systems Norway AS; 7Real Alloy Recycling INC
By switching from fossil to hydrogen fuel in melting furnaces, the CO2 footprint of a cast house in the aluminium industry can be reduced considerably. However, using hydrogen instead of fossil fuel will increase the water vapour concentration in the furnace atmosphere and likely change the oxidation behaviour of molten aluminium alloys. A series of tests have been performed where Al-Mg alloys were melted and normally held for up to 4 hours in different atmosphere compositions due to variations in fuel type and burner set-up. The results show that combustion of hydrogen in an air-fuel configuration gives more oxidation on liquid Al-Mg alloys than hydrogen in an oxy-fuel configuration. The tests also show that as little as 5% CO2 in the furnace atmosphere significantly supresses oxidation. The suppressing effect of CO2 was greater on alloys with 4.7% Mg than on alloys with 3.1 % Mg.
9:15 AM
Towards the Efficient Recycling of Used Beverage Cans: Numerical Study and Experimental Validation: Nikolaos Chamakos1; Malamatenia Koklioti1; Theofani Tzevelekou1; Athanasia Flampouri1; Ioannis Contopoulos1; Alexandros Anestis2; Grigorios Galeros2; Epameinondas Xenos2; Andreas Mavroudis2; 1ELKEME SA; 2ElvalHalcor SA
The need to maximize the efficiency in post-consumer aluminum scrap recycling processes is continuously rising in order to achieve sustainable industrial implementation of circular economy practices. The present work investigated the optimization of pre-heating process during the recycling of Used Beverage Cans (UBCs) in a multi-chamber furnace. In particular, aiming to predict the UBC temperature distribution during pre-heating, a numerical model of an industrial furnace was developed considering conduction, convection and radiation mechanisms for heat transfer. A laboratory electric resistance furnace was used to measure the UBC delacquering degree as a function of the temperature. The obtained correlation (Temperature – Delacquering Degree) was then incorporated into the numerical model rendering it a useful tool for evaluating the delacquering process. The model results were validated by industrial scale trials. Finally, the dependence of the UBC delacquering on various industrial-scale process parameters was examined.
9:40 AM Break
9:55 AM
A Novel Green Melt Technology for Aluminum Alloys: Kaborson Ke1; Xiyu Wen2; Dongjie Ke1; 1Fuzhou Metal-new High Temperature Technology Incorporation Limited; 2University of Kentucky
It is a novel green method of melt aluminum alloys that no chemical resolvent and fluxes were used. Because harmful gases and substance including Cl and F exhausted in the melting aluminum processing have been limited strictly due to environment protection, to realize green melting and digital control under industrial conditions, it is invented that argon gas by using an artificial intelligence system goes through a refractory structure with micro-pores including nano-particles in bottom of furnace; Al liquid is kept in a dynamic balance with microscale argon gas in melting processing. The ingots with low hydrogen content and the dross reducing from the processing can meet current requirements in aluminum industries. Burning loss of metal decreased and natural gas used reduced. When the system is applied with common degasser and filter system, H content and purity of the Al liquid can be controlled at low level and high grade, respectively.
10:20 AM
MagPump: Oscar Perez1; Eishin Takahashi2; Steve Iijima1; 1TST INC; 2TST Inc.
TST is a California-based company leading the way in manufacturing aluminum ingot, billet, and slab worldwide for over 76 years. TST is committed to providing the highest quality products. TST is committed to continuous improvements in its casthouse operation and has installed the world’s first and only permanent magnet-based pump, MagPump™, from Zmag (Japan). MagPump is designed to be a direct replacement for traditional mechanical pumps in side well (multi-chamber) furnaces without requiring furnace modification. MagPump is powered by zPMC™ (Zmag Permanent Magnetic Circuit) which generates virtual impellers to pump molten aluminum. Unlike mechanical pumps, MagPump does not have physical impellers and therefore is a nearly handsfree system, with no consumable parts, reduced downtime. MagPump is also capable of other applications such as gas injection (e.g., Chlorine, Nitrogen, Argon) and scrap submersion. Operator safety has been increased as the necessity to approach the pump well has been minimized.
10:45 AM
Recycling of Aluminium from Aluminium Food Tubes: Sarina Bao1; Anne Kvithyld2; Gry Aletta Bjørlykke3; Kurt Sandaunet1; 1SINTEF; 2SINTEF ; 3Kavli AS
Aluminium is often applied in packaging due to its strength and preservative capability. However, it is hard to be recycled due its thickness. In northern Europe, cream cheese, caviar, mayonnaise are stored in toothpaste like aluminium tube to extend food preservation. This paper focuses on evaluation of the recyclability of aluminium waste tubes for food from the aspect of the tube thickness, the customer habit, food residue, and pre-treatment with measurement of yield and analysis of metal quality. It was concluded that aluminium food tube is recyclable. Food residue reduced the yield from around 90% (non-used) to 50% (with 4% food residue). The change of thickness of tube did not influence the recycling yield considerably. While, less aluminium was consumed to produce thin tubes. Most of the food reside was located around the shoulder area. This calls for improvement on tube design.